chapter
stringlengths 1.97k
1.53M
| path
stringlengths 47
241
|
|---|---|
• Metric prefixes
• Yotta = 1024 Symbol: Y
• Zetta = 1021 Symbol: Z
• Exa = 1018 Symbol: E
• Peta = 1015 Symbol: P
• Tera = 1012 Symbol: T
• Giga = 109 Symbol: G
• Mega = 106 Symbol: M
• Kilo = 103 Symbol: k
• Hecto = 102 Symbol: h
• Deca = 101 Symbol: da
• Deci = 10-1 Symbol: d
• Centi = 10-2 Symbol: c
• Milli = 10-3 Symbol: m
• Micro = 10-6 Symbol: µ
• Nano = 10-9 Symbol: n
• Pico = 10-12 Symbol: p
• Femto = 10-15 Symbol: f
• Atto = 10-18 Symbol: a
• Zepto = 10-21 Symbol: z
• Yocto = 10-24 Symbol: y
Conversion factors for temperature
• oF = (oC)(9/5) + 32
• oC = (oF - 32)(5/9)
• oR = oF + 459.67
• oK = oC + 273.15
Conversion equivalencies for volume
1 US gallon (gal) = 231.0 cubic inches (in3) = 4 quarts (qt) = 8 pints (pt) = 128 fluid ounces (fl. oz.) = 3.7854 liters (l)
1 Imperial gallon (gal) = 160 fluid ounces (fl. oz.) = 4.546 liters (l)
Conversion equivalencies for distance
1 inch (in) = 2.540000 centimeter (cm)
Conversion equivalencies for velocity
1 mile per hour (mi/h) = 88 feet per minute (ft/m) = 1.46667 feet per second (ft/s) = 1.60934 kilometer per hour (km/h) = 0.44704 meter per second (m/s) = 0.868976 knot (knot—international)
Conversion equivalencies for weight
1 pound (lb) = 16 ounces (oz) = 0.45359 kilogram (kg)
Conversion equivalencies for force
1 pound-force (lbf) = 4.44822 newton (N)
Acceleration of gravity (free fall), Earth standard
9.806650 meters per second per second (m/s2) = 32.1740 feet per second per second (ft/s2)
Conversion equivalencies for area
1 acre = 43560 square feet (ft2) = 4840 square yards (yd2) = 4046.86 square meters (m2)
Conversion equivalencies for pressure
1 pound per square inch (psi) = 2.03603 inches of mercury (in. Hg) = 27.6807 inches of water (in. W.C.) = 6894.757 pascals (Pa) = 0.0680460 atmospheres (Atm) = 0.0689476 bar (bar)
Conversion equivalencies for energy or work
1 british thermal unit (BTU—“International Table”) = 251.996 calories (cal—“International Table”) = 1055.06 joules (J) = 1055.06 watt-seconds (W-s) = 0.293071 watt-hour (W-hr) = 1.05506 x 1010 ergs (erg) = 778.169 foot-pound-force (ft-lbf)
Conversion equivalencies for power
1 horsepower (hp—550 ft-lbf/s) = 745.7 watts (W) = 2544.43 british thermal units per hour (BTU/hr) = 0.0760181 boiler horsepower (hp—boiler)
Conversion equivalencies for motor torque
Locate the row corresponding to known unit of torque along the left of the table. Multiply by the factor under the column for the desired units. For example, to convert 2 oz-in torque to n-m, locate oz-in row at table left. Locate 7.062 x 10-3 at intersection of desired n-m units column. Multiply 2 oz-in x (7.062 x 10-3 ) = 14.12 x 10-3 n-m.
Converting between units is easy if you have a set of equivalencies to work with. Suppose we wanted to convert an energy quantity of 2500 calories into watt-hours. What we would need to do is find a set of equivalent figures for those units. In our reference here, we see that 251.996 calories is physically equal to 0.293071 watt hour. To convert from calories into watt-hours, we must form a “unity fraction” with these physically equal figures (a fraction composed of different figures and different units, the numerator and denominator being physically equal to one another), placing the desired unit in the numerator and the initial unit in the denominator, and then multiply our initial value of calories by that fraction.
Since both terms of the “unity fraction” are physically equal to one another, the fraction as a whole has a physical value of 1, and so does not change the true value of any figure when multiplied by it. When units are canceled, however, there will be a change in units. For example, 2500 calories multiplied by the unity fraction of (0.293071 w-hr / 251.996 cal) = 2.9075 watt-hours.
The “unity fraction” approach to unit conversion may be extended beyond single steps. Suppose we wanted to convert a fluid flow measurement of 175 gallons per hour into liters per day. We have two units to convert here: gallons into liters, and hours into days. Remember that the word “per” in mathematics means “divided by,” so our initial figure of 175 gallons per hour means 175 gallons divided by hours. Expressing our original figure as such a fraction, we multiply it by the necessary unity fractions to convert gallons to liters (3.7854 liters = 1 gallon), and hours to days (1 day = 24 hours). The units must be arranged in the unity fraction in such a way that undesired units cancel each other out above and below fraction bars. For this problem it means using a gallons-to-liters unity fraction of (3.7854 liters / 1 gallon) and a hours-to-days unity fraction of (24 hours / 1 day):
Our final (converted) answer is 15898.68 liters per day. | textbooks/workforce/Electronics_Technology/Book%3A_Electric_Circuits_V_-_References_(Kuphaldt)/01%3A_Useful_Equations_And_Conversion_Factors/1.10%3A_Metric_Prefixes_and_Unit_Conversions.txt |
Standard Resistor Values and Color
Components and wires are coded with colors to identify their value and function.
The colors brown, red, green, blue, and violet are used as tolerance codes on 5-band resistors only. All 5-band resistors use a colored tolerance band. The blank (20%) “band” is only used with the “4-band” code (3 colored bands + a blank “band”).
\
Example #1
A resistor colored Yellow-Violet-Orange-Gold would be 47 kΩ with a tolerance of +/- 5%.
Example #2
A resistor colored Green-Red-Gold-Silver would be 5.2 Ω with a tolerance of +/- 10%.
Example #3
A resistor colored White-Violet-Black would be 97 Ω with a tolerance of +/- 20%. When you see only three color bands on a resistor, you know that it is actually a 4-band code with a blank (20%) tolerance band.
Example #4
A resistor colored Orange-Orange-Black-Brown-Violet would be 3.3 kΩ with a tolerance of +/- 0.1%.
Example #5
A resistor colored Brown-Green-Grey-Silver-Red would be 1.58 Ω with a tolerance of +/- 2%.
Example #6
A resistor colored Blue-Brown-Green-Silver-Blue would be 6.15 Ω with a tolerance of +/- 0.25%.
Preferred Values or E-series
To make mass manufacturing of resistors easier, the IEC (International Electrotechnical Commision) defined tolerance and resistance values for resistors in 1952. These are referred to as preferred values or E-series, published in standard IEC 60063:1963. Capactors, Zener diodes, and inductors also use these standards.
The purpose of this was so that when companies produce resistors with different values of resistance, they would equally space on a logarithmic scale. This helps the supplier with stocking different values. Resistors produced by different manufacturers are compatible for the same designs because of the use of standard values.
Standard Resistor Value Series and Tolerances
The standard E3, E6, E12, E24, E48 and E96 resistor values are listed below.
*The calculated tolerance for this series is 36.60%, While the standard only specifies a tolerance greater than 20%, other sources indicate 40% or 50%.
E3 Resistor Series
These are the most widely used resistor series in the electronics industry.
E96 Resistor Series and Beyond
The E96 and E192 series of standard resistor values do exist, but they are not used as much as the Series mention previously.
2.02: Wiring Color Codes
Wiring for AC and DC power distribution branch circuits are color-coded for the identification of individual wires. In some jurisdictions, all wire colors are specified in legal documents. In other jurisdictions, only a few conductor colors are so codified. In that case, local custom dictates the “optional” wire colors.
IEC, AC: Most of Europe abides by IEC (International Electrotechnical Commission) wiring color codes for AC branch circuits. These are listed in the Table below. The older color codes in the table reflect the previous style which did not account for proper phase rotation. The protective ground wire (listed as green-yellow) is green with a yellow stripe.
UK, AC: The United Kingdom now follows the IEC AC wiring color codes. The Table below lists these along with the obsolete domestic color codes. For adding new colored wiring to existing old colored wiring see Cook. [PCk]
US, AC: The US National Electrical Code only mandates white (or grey) for the neutral power conductor and bare copper, green, or green with a yellow stripe for the protective ground. In principle, any other colors except these may be used for the power conductors. The colors adopted as a local practice are shown in the Table below. Black, red, and blue are used for 208 VAC three-phase; brown, orange, and yellow are used for 480 VAC. Conductors larger than #6 AWG are only available in black and are color taped at the ends.
Canada: Canadian wiring is governed by the CEC (Canadian Electric Code). See Table below. The protective ground is green or green with a yellow stripe. The neutral is white, the hot (live or active) single-phase wires are black, and red in the case of a second active. Three-phase lines are red, black, and blue.
IEC, DC: DC power installations, for example, solar power and computer data centers, use color-coding which follows the AC standards. The IEC color standard for DC power cables is listed in Table below, adapted from Table 2, Cook. [PCk]
US DC power: The US National Electrical Code (for both AC and DC) mandates that the grounded neutral conductor of a power system be white or grey. The protective ground must be bare, green, or green-yellow striped. Hot (active) wires may be any other colors except these. However, common practice (per local electrical inspectors) is for the first hot (live or active) wire to be black and the second hot to be red. The recommendations in the Table below are by Wiles. [JWi] He makes no recommendation for ungrounded power system colors. Usage of the ungrounded system is discouraged for safety. However, red (+) and black (-) follows the coloring of the grounded systems in the table. | textbooks/workforce/Electronics_Technology/Book%3A_Electric_Circuits_V_-_References_(Kuphaldt)/02%3A_Color_Codes/2.01%3A_Resistor_Color_Codes.txt |
Wiring Color Codes Infographic. Released under the Creative Commons Attribution-ShareAlike License
Looking for Wiring & Resistor Calculators?
View our Wire & Resistor calculators in our Tools section.
Basic Wire Color Code Information by Region
Many of the wire identifications standards rely on color codes. Which standard should you be using for your project? It depends on your location, voltage, and other important factors.
Note: Older installations may use different color codes. It is always a great idea to document the color code that’s being followed. This makes work safer, and any future maintenance needed, easier.
U.S. Wiring Color Codes
In the USA, color codes are usually utilized for power wires in “branch circuits,” the wiring between the last protective device like a circuit breaker and the load (like an appliance).
AC Wire Colors For 120/208/240 Volts
These are commonly found in home and office settings.
• Phase 1 - Black
• Phase 2 - Red
• Phase 3 - Blue
• Neutral - White
• Ground - Green, Green with Yellow Stripe, or Bare Wire
If one phase of your wiring is at a higher voltage than others, using a high-leg connection, wires should be marked orange for that phase. High-leg connections are typically uncommon in newer installations.
AC Wire Colors For 277/480 Volt
Industrial motors and equipment typically have higher voltage systems.
• Phase 1 - Brown
• Phase 2 - Orange
• Phase 3 - Yellow
• Neutral - Gray
• Ground - Green, Green with Yellow Stripe, or Bare Wire
It is very important to have a documented wire labeling system for higher voltage systems. Labels should include information regarding the circuit, and the appropriate disconnection point for lockout/tagout.
Wire Colors for DC Power
DC or Direct Current, is typically used in battery systems and solar power systems, instead of AC or Alternating Current.
• Positive (non-ground) - Red
• Negative (non-ground) - Black
• Ground - White or Gray
International Wiring Color Codes
International wire color codes are often specified by law depending on your location, though most rely on common practice, below we cover Europe and Canada.
Wire Color Codes for Europe (IEC)
The International Electrotechnical Commission (or IEC) has established a wire color code for most European countries for AC “branch” circuits.
• Phase 1 - Brown
• Phase 2 - Black
• Phase 3 - Grey
• Neutral - Blue
• Ground - Green with Yellow Stripe
Canadian AC Wiring Color Codes
Wiring Color code standards are set in place by the Canadian Electric Code (or CEC) in Canada. The color code is very similar to the U.S.A’s color code.
• Phase 1 - Red
• Phase 2 - Black
• Phase 3 - Blue
• Neutral - White
• Ground - Green with Yellow Stripe
When are Color Codes Applied to Wiring?
The manufacturer of most narrow wires will color code them, utilizing insulation of different colors. Wires that are manufactured with black insulation are typically larger than #6 AWG. Color coding should always be added during installation with color bands that wrap around the wire.
Self-laminating wire wraps and heat-shrink tubes should be utilized to create clean and professional labels for your projects.
3.01: Copper Wire Gauge Table
Solid Cooper Wire Table
Size
Diameter
(inches)
Cross-sectional area
(cir. mils)
Cross-sectional area
(sq. inches)
Weight
(lb/1000ft)
4/0 0.4600 211,600 0.1662 640.5
3/0 0.4096 167,800 0.1318 507.9
2/0 0.3648 133,100 0.1045 402.8
1/0 0.3249 105,500 0.08289 319.5
1 0.2893 83,690 0.06573 253.5
2 0.2576 66,370 0.05213 200.9
3 0.2294 52,630 0.04134 159.3
4 0.2043 41,740 0.03278 126.4
5 0.1819 33,100 0.02600 100.2
6 0.1620 26,250 0.02062 79.46
7 0.1443 20,820 0.01635 63.02
8 0.1285 16,510 0.01297 49.97
9 0.1144 13,090 0.01028 39.63
10 0.1019 10,380 0.008155 31.43
11 0.09074 8,234 0.006467 24.92
12 0.08081 6,530 0.005129 19.77
13 0.07196 5,178 0.004067 15.68
14 0.06408 4,107 0.003225 12.43
15 0.05707 3,257 0.002558 9.858
16 0.05082 2,583 0.002028 7.818
17 0.04526 2,048 0.001609 6.200
18 0.04030 1,624 0.001276 4.917
19 0.03589 1,288 0.001012 3.899
20 0.03196 1,022 0.0008023 3.092
21 0.02846 810.1 0.0006363 2.452
22 0.02535 642.5 0.0005046 1.945
23 0.02257 509.5 0.0004001 1.542
24 0.02010 404.0 0.0003173 1.233
25 0.01790 320.4 0.0002517 0.9699
26 0.01594 254.1 0.0001996 0.7692
27 0.01420 201.5 0.0001583 0.6100
28 0.01264 159.8 0.0001255 0.4837
29 0.01126 126.7 0.00009954 0.3836
30 0.01003 100.5 0.00007894 0.3042
31 0.008928 79.70 0.00006260 0.2413
32 0.007950 63.21 0.00004964 0.1913
33 0.007080 50.13 0.00003937 0.1517
34 0.006305 39.75 0.00003122 0.1203
35 0.005615 31.52 0.00002476 0.09542
36 0.005000 25.00 0.00001963 0.07567
37 0.004453 19.83 0.00001557 0.06001
38 0.003965 15.72 0.00001235 0.04759
39 0.003531 12.47 0.000009793 0.03774
40 0.003145 9.888 0.000007766 0.02993
41 0.002800 7.842 0.000006159 0.02374
42 0.002494 6.219 0.000004884 0.01882
43 0.002221 4.932 0.000003873 0.01493
44 0.001978 3.911 0.000003072 0.01184
3.02: Copper Wire Ampacity Table
Ampacities of copper wire, in free air at 30o C:
* = estimated values; normally, wire gages this small are not manufactured with these insulation types.
3.03: Coefficients of Specific Resistance
Specific resistance at 20o C:
* = Steel alloy at 99.5 percent iron, 0.5 percent carbon.
3.04: Temperature Coefficients of Resistance
Temperature coefficient (α) per degree C:
* = Steel alloy at 99.5 percent iron, 0.5 percent carbon
3.05: Critical Temperatures for Superconductors
Critical temperatures given in Kelvins
Note: all critical temperatures given at zero magnetic field strength.
3.06: Dielectric Strengths for Insulators
Dielectric strength in kilovolts per inch (kV/in):
* = Materials listed are specially prepared for electrical use | textbooks/workforce/Electronics_Technology/Book%3A_Electric_Circuits_V_-_References_(Kuphaldt)/02%3A_Color_Codes/2.03%3A_Wiring_Color_Codes_Infographic.txt |
Note: while division by zero is popularly thought to be equal to infinity, this is not technically true. In some practical applications it may be helpful to think the result of such a fraction approaching positive infinity as a positive denominator approaches zero (imagine calculating current I=E/R in a circuit with resistance approaching zero—current would approach infinity), but the actual fraction of anything divided by zero is undefined in the scope of either real or complex numbers.
4.02: Arithmetic Properties
The associative property
In addition and multiplication, terms may be arbitrarily associated with each other through the use of parentheses:
The commutative property
In addition and multiplication, terms may be arbitrarily interchanged, or commutated:
4.04: Radicals
Definition of a radical
When people talk of a “square root,” they’re referring to a radical with a root of 2. This is mathematically equivalent to a number raised to the power of 1/2. This equivalence is useful to know when using a calculator to determine a strange root. Suppose for example you needed to find the fourth root of a number, but your calculator lacks a “4th root” button or function. If it has a yx function (which any scientific calculator should have), you can find the fourth root by raising that number to the 1/4 power, or x0.25.
It is important to remember that when solving for an even root (square root, fourth root, etc.) of any number, there are two valid answers. For example, most people know that the square root of nine is three, but negative three is also a valid answer, since (-3)2 = 9 just as 32 = 9.
4.05: Important Constants
Euler’s number
Euler’s constant is an important value for exponential functions, especially scientific applications involving decay (such as the decay of a radioactive substance). It is especially important in calculus due to its uniquely self-similar properties of integration and differentiation.
Pi
Pi (π) is defined as the ratio of a circle’s circumference to its diameter.
Note: For both Euler’s constant (e) and pi (π), the spaces shown between each set of five digits have no mathematical significance. They are placed there just to make it easier for your eyes to “piece” the number into five-digit groups when manually copying.
4.06: Logarithms
Definition of a logarithm
“log” denotes a common logarithm (base = 10), while “ln” denotes a natural logarithm (base = e).
Properties of logarithms
These properties of logarithms come in handy for performing complex multiplication and division operations. They are an example of something called a transform function, whereby one type of mathematical operation is transformed into another type of mathematical operation that is simpler to solve. Using a table of logarithm figures, one can multiply or divide numbers by adding or subtracting their logarithms, respectively. then looking up that logarithm figure in the table and seeing what the final product or quotient is.
Slide rules work on this principle of logarithms by performing multiplication and division through addition and subtraction of distances on the slide.
Marks on a slide rule’s scales are spaced in a logarithmic fashion, so that a linear positioning of the scale or cursor results in a nonlinear indication as read on the scale(s). Adding or subtracting lengths on these logarithmic scales results in an indication equivalent to the product or quotient, respectively, of those lengths.
Most slide rules were also equipped with special scales for trigonometric functions, powers, roots, and other useful arithmetic functions.
4.09: Sequences
Arithmetic sequences
An arithmetic sequence is a series of numbers obtained by adding (or subtracting) the same value with each step. A child’s counting sequence (1, 2, 3, 4, . . .) is a simple arithmetic sequence, where the common difference is 1: that is, each adjacent number in the sequence differs by a value of one. An arithmetic sequence counting only even numbers (2, 4, 6, 8, . . .) or only odd numbers (1, 3, 5, 7, 9, . . .) would have a common difference of 2.
In the standard notation of sequences, a lower-case letter “a” represents an element (a single number) in the sequence. The term “an” refers to the element at the nth step in the sequence. For example, “a3” in an even-counting (common difference = 2) arithmetic sequence starting at 2 would be the number 6, “a” representing 4 and “a1” representing the starting point of the sequence (given in this example as 2).
A capital letter “A” represents the sum of an arithmetic sequence. For instance, in the same even-counting sequence starting at 2, A4 is equal to the sum of all elements from a1 through a4, which of course would be 2 + 4 + 6 + 8, or 20.
Geometric sequences
A geometric sequence, on the other hand, is a series of numbers obtained by multiplying (or dividing) by the same value with each step. A binary place-weight sequence (1, 2, 4, 8, 16, 32, 64, . . .) is a simple geometric sequence, where the common ratio is 2: that is, each adjacent number in the sequence differs by a factor of two.
4.10: Factorials
Definition of a factorial
Denoted by the symbol “!” after an integer; the product of that integer and all integers in descent to 1.
Example of a factorial: | textbooks/workforce/Electronics_Technology/Book%3A_Electric_Circuits_V_-_References_(Kuphaldt)/04%3A_Algebra_Reference/4.01%3A_Basic_identities.txt |
What are Simultaneous Equations and Systems of Equations?
The terms simultaneous equations and systems of equations refer to conditions where two or more unknown variables are related to each other through an equal number of equations.
Example:
For this set of equations, there is but a single combination of values for x and y that will satisfy both. Either equation, considered separately, has an infinitude of valid (x,y) solutions, but together there is only one. Plotted on a graph, this condition becomes obvious:
Each line is actually a continuum of points representing possible x and y solution pairs for each equation. Each equation, separately, has an infinite number of ordered pair (x,y) solutions. There is only one point where the two linear functions x + y = 24 and 2x - y = -6 intersect (where one of their many independent solutions happen to work for both equations), and that is where x is equal to a value of 6 and yis equal to a value of 18.
Usually, though, graphing is not a very efficient way to determine the simultaneous solution set for two or more equations. It is especially impractical for systems of three or more variables. In a three-variable system, for example, the solution would be found by the point intersection of three planes in a three-dimensional coordinate space—not an easy scenario to visualize.
Solving Simultaneous Equations Using The Substitution Method
Several algebraic techniques exist to solve simultaneous equations. Perhaps the easiest to comprehend is the substitution method.
Take, for instance, our two-variable example problem:
In the substitution method, we manipulate one of the equations such that one variable is defined in terms of the other:
Then, we take this new definition of one variable and substitute it for the same variable in the other equation. In this case, we take the definition of y, which is 24 - x and substitute this for the y term found in the other equation:
Now that we have an equation with just a single variable (x), we can solve it using “normal” algebraic techniques:
Now that x is known, we can plug this value into any of the original equations and obtain a value for y. Or, to save us some work, we can plug this value (6) into the equation we just generated to define y in terms of x, being that it is already in a form to solve for y:
Applying the substitution method to systems of three or more variables involves a similar pattern, only with more work involved. This is generally true for any method of solution: the number of steps required for obtaining solutions increases rapidly with each additional variable in the system.
To solve for three unknown variables, we need at least three equations. Consider this example:
Being that the first equation has the simplest coefficients (1, -1, and 1, for x, y, and z, respectively), it seems logical to use it to develop a definition of one variable in terms of the other two. In this example, I’ll solve for x in terms of y and z:
Now, we can substitute this definition of x where x appears in the other two equations:
Reducing these two equations to their simplest forms:
So far, our efforts have reduced the system from three variables in three equations to two variables in two equations. Now, we can apply the substitution technique again to the two equations 4y - z = 4 and -3y + 4z = 36 to solve for either y or z. First, I’ll manipulate the first equation to define z in terms of y:
Next, we’ll substitute this definition of z in terms of y where we see z in the other equation:
Now that y is a known value, we can plug it into the equation defining z in terms of y and obtain a figure for z:
Now, with values for y and z known, we can plug these into the equation where we defined x in terms of y and z, to obtain a value for x:
In closing, we’ve found values for x, y, and z of 2, 4, and 12, respectively, that satisfy all three equations.
Solving Simultaneous Equations Using The Addition Method
While the substitution method may be the easiest to grasp on a conceptual level, there are other methods of solution available to us. One such method is the so-called addition method, whereby equations are added to one another for the purpose of canceling variable terms.
Let’s take our two-variable system used to demonstrate the substitution method:
One of the most-used rules of algebra is that you may perform any arithmetic operation you wish to an equation so long as you do it equally to both sides. With reference to addition, this means we may add any quantity we wish to both sides of an equation—so long as its the same quantity—without altering the truth of the equation.
An option we have, then, is to add the corresponding sides of the equations together to form a new equation. Since each equation is an expression of equality (the same quantity on either side of the = sign), adding the left-hand side of one equation to the left-hand side of the other equation is valid so long as we add the two equations’ right-hand sides together as well. In our example equation set, for instance, we may add x + y to 2x - y, and add 24 and -6 together as well to form a new equation. What benefit does this hold for us? Examine what happens when we do this to our example equation set:
Because the top equation happened to contain a positive y term while the bottom equation happened to contain a negative y term, these two terms canceled each other in the process of addition, leaving no y term in the sum. What we have left is a new equation, but one with only a single unknown variable, x! This allows us to easily solve for the value of x:
Once we have a known value for x, of course, determining y‘s value is a simply matter of substitution (replacing x with the number 6) into one of the original equations. In this example, the technique of adding the equations together worked well to produce an equation with a single unknown variable. What about an example where things aren’t so simple? Consider the following equation set:
We could add these two equations together—this being a completely valid algebraic operation—but it would not profit us in the goal of obtaining values for x and y:
The resulting equation still contains two unknown variables, just like the original equations do, and so we’re no further along in obtaining a solution. However, what if we could manipulate one of the equations so as to have a negative term that would cancel the respective term in the other equation when added? Then, the system would reduce to a single equation with a single unknown variable just as with the last (fortuitous) example.
If we could only turn the y term in the lower equation into a - 2y term, so that when the two equations were added together, both y terms in the equations would cancel, leaving us with only an x term, this would bring us closer to a solution. Fortunately, this is not difficult to do. If we multiply each and every term of the lower equation by a -2, it will produce the result we seek:
Now, we may add this new equation to the original, upper equation:
Solving for x, we obtain a value of 3:
Substituting this new-found value for x into one of the original equations, the value of y is easily determined:
Using this solution technique on a three-variable system is a bit more complex. As with substitution, you must use this technique to reduce the three-equation system of three variables down to two equations with two variables, then apply it again to obtain a single equation with one unknown variable. To demonstrate, I’ll use the three-variable equation system from the substitution section:
Being that the top equation has coefficient values of 1 for each variable, it will be an easy equation to manipulate and use as a cancellation tool. For instance, if we wish to cancel the 3x term from the middle equation, all we need to do is take the top equation, multiply each of its terms by -3, then add it to the middle equation like this:
We can rid the bottom equation of its -5x term in the same manner: take the original top equation, multiply each of its terms by 5, then add that modified equation to the bottom equation, leaving a new equation with only y and z terms:
At this point, we have two equations with the same two unknown variables, y and z:
By inspection, it should be evident that the -z term of the upper equation could be leveraged to cancel the 4z term in the lower equation if only we multiply each term of the upper equation by 4 and add the two equations together:
Taking the new equation 13y = 52 and solving for y (by dividing both sides by 13), we get a value of 4 for y. Substituting this value of 4 for y in either of the two-variable equations allows us to solve for z. Substituting both values of y and z into any one of the original, three-variable equations allows us to solve for x. The final result (I’ll spare you the algebraic steps since you should be familiar with them by now!) is that x = 2, y = 4, and z = 12. | textbooks/workforce/Electronics_Technology/Book%3A_Electric_Circuits_V_-_References_(Kuphaldt)/04%3A_Algebra_Reference/4.11%3A_Solving_Simultaneous_Equations-_The_Substitution_Method_and_the_Addition_Method.txt |
A right triangle is defined as having one angle precisely equal to 90o (a right angle).
Trigonometric Identities
H is the Hypotenuse, always being opposite the right angle. Relative to angle x, O is the Opposite and A is the Adjacent.
“Arc” functions such as “arcsin”, “arccos”, and “arctan” are the complements of normal trigonometric functions. These functions return an angle for a ratio input. For example, if the tangent of 45o is equal to 1, then the “arctangent” (arctan) of 1 is 45o. “Arc” functions are useful for finding angles in a right triangle if the side lengths are known.
5.04: Hyperbolic Functions
Note: all angles (x) must be expressed in units of radians for these hyperbolic functions. There are 2π radians in a circle (360o).
6.02: Derivative of a Constant
(“c” being a constant)
6.04: Derivatives of Power Functions of e
Proportionality Constant
When we say that a relationship or phenomenon is “exponential,” we are implying that some quantity—electric current, profits, population—increases more rapidly as the quantity grows. In other words, the rate of change with respect to a given variable is proportional to the value of that variable. This means that the derivative of an exponential function is equal to the original exponential function multiplied by a constant (k) that establishes proportionality.
The proportionality constant is equal to the natural log of the base of the exponent:
It follows, then, that if the natural log of the base is equal to one, the derivative of the function will be equal to the original function. This is exactly what happens with power functions of e: the natural log of e is 1, and consequently, the derivative of ex is ex.
The “Chain” Rule
When the exponential expression is something other than simply x, we apply the chain rule: First we take the derivative of the entire expression, then we multiply it by the derivative of the expression in the exponent.
This technique can be used to find the rate of change of diode current with respect to diode voltage.
The following equation provides an approximate relationship between the voltage across a diode ($V_D$)and the current through a diode($I_D$):
(See the page on diodes and rectifiers for more information on the diode current–voltage equation; also, note that ($I_S$) is a constant, not a variable.) To find the rate of change of current with respect to voltage, we take the derivative:
Thus, at a given value of diode voltage ($V_D$) , an incremental increase in voltage will create an increase in current equal to \frac{I_S}{0.026}e^\frac{V_D}{0.026}\]
6.07: The Antiderivative (Indefinite Integral)
Notice something important here: taking the derivative of f(x) may precisely give you g(x), but taking the antiderivative of g(x) does not necessarily give you f(x) in its original form. Example:
Note that the constant c is unknown! The original function f(x) could have been 3x2 + 5, 3x2 + 10, 3x2 + anything, and the derivative of f(x) would have still been 6x. Determining the antiderivative of a function, then, is a bit less certain than determining the derivative of a function.
6.09: Antiderivatives of Power Functions of e
Note: this is a very unique and useful property of e. As in the case of derivatives, the antiderivative of such a function is that same function. In the case of the antiderivative, a constant term “c” is added to the end as well.
6.12: Differential Equations
As opposed to normal equations where the solution is a number, a differential equation is one where the solution is actually a function, and which at least one derivative of that unknown function is part of the equation.
As with finding antiderivatives of a function, we are often left with a solution that encompasses more than one possibility (consider the many possible values of the constant “c” typically found in antiderivatives). The set of functions which answer any differential equation is called the “general solution” for that differential equation. Any one function out of that set is referred to as a “particular solution” for that differential equation. The variable of reference for differentiation and integration within the differential equation is known as the “independent variable. | textbooks/workforce/Electronics_Technology/Book%3A_Electric_Circuits_V_-_References_(Kuphaldt)/05%3A_Trigonometry_Reference/5.01%3A_Right_Triangle_Trigonometry.txt |
“With Electronics Workbench, you can create circuit schematics that look just the same as those you’re already familiar with on paper—plus you can flip the power switch so the schematic behaves like a real circuit. With other electronics simulators, you may have to type in SPICE node lists as text files—an abstract representation of a circuit beyond the capabilities of all but advanced electronics engineers.”
—(Electronics Workbench User’s guide—version 4, page 7)
This introduction comes from the operating manual for a circuit simulation program called Electronics Workbench. Using a graphic interface, it allows the user to draw a circuit schematic and then have the computer analyze that circuit, displaying the results in graphic form. It is a very valuable analysis tool, but it has its shortcomings. For one, it and other graphic programs like it tend to be unreliable when analyzing complex circuits, as the translation from picture to computer code is not quite the exact science we would want it to be (yet). Secondly, due to its graphics requirements, it tends to need a significant amount of computational “horsepower” to run, and a computer operating system that supports graphics. Thirdly, these graphic programs can be costly.
However, underneath the graphics skin of Electronics Workbench lies a robust (and free!) program called SPICE, which analyzes a circuit based on a text-file description of the circuit’s components and connections. What the user pays for with Electronics Workbench and other graphic circuit analysis programs is the convenient “point and click” interface, while SPICE does the actual mathematical analysis.
By itself, SPICE does not require a graphic interface and demands little in system resources. It is also very reliable. The makers of Electronic Workbench would like you to think that using SPICE in its native text mode is a task suited for rocket scientists, but I’m writing this to prove them wrong. SPICE is fairly easy to use for simple circuits, and its non-graphic interface actually lends itself toward the analysis of circuits that can be difficult to draw. I think it was the programming expert Donald Knuth who quipped, “What you see is all you get” when it comes to computer applications. Graphics may look more attractive, but abstracted interfaces (text) are actually more efficient.
This document is not intended to be an exhaustive tutorial on how to use SPICE. I’m merely trying to show the interested user how to apply it to the analysis of simple circuits, as an alternative to proprietary (\$\$\$) and buggy programs. Once you learn the basics, there are other tutorials better suited to take you further. Using SPICE—a program originally intended to develop integrated circuits—to analyze some of the really simple circuits showcased here may seem a bit like cutting butter with a chain saw, but it works!
All options and examples have been tested on SPICE version 2g6 on both MS-DOS and Linux operating systems. As far as I know, I’m not using features specific to version 2g6, so these simple functions should work on most versions of SPICE.
7.02: History of SPICE
SPICE is a computer program designed to simulate analog electronic circuits. Its original intent was for the development of integrated circuits, from which it derived its name: Simulation Program with Integrated Circuit Emphasis.
The origin of SPICE traces back to another circuit simulation program called CANCER. Developed by professor Ronald Rohrer of U.C. Berkeley along with some of his students in the late 1960’s, CANCER continued to be improved through the early 1970’s. When Rohrer left Berkeley, CANCER was re-written and re-named to SPICE, released as version 1 to the public domain in May of 1972. Version 2 of SPICE was released in 1975 (version 2g6—the version used in this book—is a minor revision of this 1975 release). Instrumental in the decision to release SPICE as a public-domain computer program was professor Donald Pederson of Berkeley, who believed that all significant technical progress happens when information is freely shared. I for one thank him for his vision.
A major improvement came about in March of 1985 with version 3 of SPICE (also released under public domain). Written in the C language rather than FORTRAN, version 3 incorporated additional transistor types (the MESFET, for example), and switch elements. Version 3 also allowed the use of alphabetical node labels rather than only numbers. Instructions written for version 2 of SPICE should still run in version 3, though.
Despite the additional power of version 3, I have chosen to use version 2g6 throughout this book because it seems to be the easiest version to acquire and run on different computer systems. | textbooks/workforce/Electronics_Technology/Book%3A_Electric_Circuits_V_-_References_(Kuphaldt)/07%3A_Using_The_spice_Circuit_Simulation_Program/7.01%3A_Introduction_to_SPICE.txt |
Programming a circuit simulation with SPICE is much like programming in any other computer language: you must type the commands as text in a file, save that file to the computer’s hard drive, and then process the contents of that file with a program (compiler or interpreter) that understands such commands.
In an interpreted computer language, the computer holds a special program called an interpreter that translates the program you wrote (the so-called source file) into the computer’s own language, on the fly, as its being executed:
In a compiled computer language, the program you wrote is translated all at once into the computer’s own language by a special program called a compiler. After the program you’ve written has been “compiled,” the resulting executable file needs no further translation to be understood directly by the computer. It can now be “run” on a computer whether or not compiler software has been installed on that computer:
SPICE is an interpreted language. In order for a computer to be able to understand the SPICE instructions you type, it must have the SPICE program (interpreter) installed:
SPICE source files are commonly referred to as “netlists,” although they are sometimes known as “decks” with each line in the file being called a “card.” Cute, don’t you think? Netlists are created by a person like yourself typing instructions line-by-line using a word processor or text editor. Text editors are much preferred over word processors for any type of computer programming, as they produce pure ASCII text with no special embedded codes for text highlighting (like italic or boldface fonts), which are uninterpretable by interpreter and compiler software.
As in general programming, the source file you create for SPICE must follow certain conventions of programming. It is a computer language in itself, albeit a simple one. Having programmed in BASIC and C/C++, and having some experience reading PASCAL and FORTRAN programs, it is my opinion that the language of SPICE is much simpler than any of these. It is about the same complexity as a markup language such as HTML, perhaps less so.
There is a cycle of steps to be followed in using SPICE to analyze a circuit. The cycle starts when you first invoke the text editing program and make your first draft of the netlist. The next step is to run SPICE on that new netlist and see what the results are. If you are a novice user of SPICE, your first attempts at creating a good netlist will be fraught with small errors of syntax. Don’t worry—as every computer programmer knows, proficiency comes with lots of practice. If your trial run produces error messages or results that are obviously incorrect, you need to re-invoke the text editing program and modify the netlist. After modifying the netlist, you need to run SPICE again and check the results. The sequence, then, looks something like this:
• Compose a new netlist with a text editing program. Save that netlist to a file with a name of your choice.
• Run SPICE on that netlist and observe the results.
• If the results contain errors, start up the text editing program again and modify the netlist.
• Run SPICE again and observe the new results.
• If there are still errors in the output of SPICE, re-edit the netlist again with the text editing program. Repeat this cycle of edit/run as many times as necessary until you are getting the desired results.
• Once you’ve “debugged” your netlist and are getting good results, run SPICE again, only this time redirecting the output to a new file instead of just observing it on the computer screen.
• Start up a text editing program or a word processor program and open the SPICE output file you just created. Modify that file to suit your formatting needs and either save those changes to disk and/or print them out on paper.
To “run” a SPICE “program,” you need to type in a command at a terminal prompt interface, such as that found in MS-DOS, UNIX, or the MS-Windows DOS prompt option:
`spice < example.cir `
The word “spice” invokes the SPICE interpreting program (providing that the SPICE software has been installed on the computer!), the “<” symbol redirects the contents of the source file to the SPICE interpreter, and example.cir is the name of the source file for this circuit example. The file extension “.cir” is not mandatory; I have seen “.inp” (for “input”) and just plain “.txt” work well, too. It will even work when the netlist file has no extension. SPICE doesn’t care what you name it, so long as it has a name compatible with the filesystem of your computer (for old MS-DOS machines, for example, the filename must be no more than 8 characters in length, with a 3 character extension, and no spaces or other non-alphanumerical characters).
When this command is typed in, SPICE will read the contents of the example.cir file, analyze the circuit specified by that file, and send a text report to the computer terminal’s standard output (usually the screen, where you can see it scroll by). A typical SPICE output is several screens worth of information, so you might want to look it over with a slight modification of the command:
`spice < example.cir | more `
This alternative “pipes” the text output of SPICE to the “more” utility, which allows only one page to be displayed at a time. What this means (in English) is that the text output of SPICE is halted after one screen-full, and waits until the user presses a keyboard key to display the next screen-full of text. If you’re just testing your example circuit file and want to check for any errors, this is a good way to do it.
`spice < example.cir > example.txt `
This second alternative (above) redirects the text output of SPICE to another file, called example.txt, where it can be viewed or printed. This option corresponds to the last step in the development cycle listed earlier. It is recommended by this author that you use this technique of “redirection” to a text file only after you’ve proven your example circuit netlist to work well, so that you don’t waste time invoking a text editor just to see the output during the stages of “debugging.”
Once you have a SPICE output stored in a .txt file, you can use a text editor or (better yet!) a word processor to edit the output, deleting any unnecessary banners and messages, even specifying alternative fonts to highlight the headings and/or data for a more polished appearance. Then, of course, you can print the output to paper if you so desire. Being that the direct SPICE output is plain ASCII text, such a file will be universally interpretable on any computer whether SPICE is installed on it or not. Also, the plain text format ensures that the file will be very small compared to the graphic screen-shot files generated by “point-and-click” simulators.
The netlist file format required by SPICE is quite simple. A netlist file is nothing more than a plain ASCII text file containing multiple lines of text, each line describing either a circuit component or special SPICE command. Circuit architecture is specified by assigning numbers to each component’s connection points in each line, connections between components designated by common numbers. Examine the following example circuit diagram and its corresponding SPICE file. Please bear in mind that the circuit diagram exists only to make the simulation easier for human beings to understand. SPICE only understands netlists:
```Example netlist
v1 1 0 dc 15
r1 1 0 2.2k
r2 1 2 3.3k
r3 2 0 150
.end
```
Each line of the source file shown above is explained here:
• v1 represents the battery (voltage source 1), positive terminal numbered 1, negative terminal numbered 0, with a DC voltage output of 15 volts.
• r1 represents resistor R1 in the diagram, connected between points 1 and 0, with a value of 2.2 kΩ.
• r2 represents resistor R2 in the diagram, connected between points 1 and 2, with a value of 3.3 kΩ.
• r3 represents resistor R3 in the diagram, connected between points 2 and 0, with a value of 150 kΩ.
Electrically common points (or “nodes”) in a SPICE circuit description share common numbers, much in the same way that wires connecting common points in a large circuit typically share common wire labels.
To simulate this circuit, the user would type those six lines of text on a text editor and save them as a file with a unique name (such as example.cir). Once the netlist is composed and saved to a file, the user then processes that file with one of the command-line statements shown earlier (spice < example.cir), and will receive this text output on their computer’s screen:
```1*******10/10/99 ******** spice 2g.6 3/15/83 ********07:32:42*****
0example netlist
0**** input listing temperature = 27.000 deg c
v1 1 0 dc 15
r1 1 0 2.2k
r2 1 2 3.3k
r3 2 0 150
.end
*****10/10/99 ********* spice 2g.6 3/15/83 ******07:32:42******
0example netlist
0**** small signal bias solution temperature = 27.000 deg c
node voltage node voltage
( 1) 15.0000 ( 2) 0.6522
voltage source currents
name current
v1 -1.117E-02
total power dissipation 1.67E-01 watts
job concluded
0 total job time 0.02
1*******10/10/99 ******** spice 2g.6 3/15/83 ******07:32:42*****
0**** input listing temperature = 27.000 deg c
```
SPICE begins by printing the time, date, and version used at the top of the output. It then lists the input parameters (the lines of the source file), followed by a display of DC voltage readings from each node (reference number) to ground (always reference number 0). This is followed by a list of current readings through each voltage source (in this case there’s only one, v1). Finally, the total power dissipation and computation time in seconds is printed.
All output values provided by SPICE are displayed in scientific notation.
The SPICE output listing shown above is a little verbose for most peoples’ taste. For a final presentation, it might be nice to trim all the unnecessary text and leave only what matters. Here is a sample of that same output, redirected to a text file (spice < example.cir > example.txt), then trimmed down judiciously with a text editor for final presentation and printed:
```example netlist
v1 1 0 dc 15
r1 1 0 2.2k
r2 1 2 3.3k
r3 2 0 150
.end
```
```node voltage node voltage
( 1) 15.0000 ( 2) 0.6522
```
```voltage source currents
name current
v1 -1.117E-02
```
```total power dissipation 1.67E-01 watts
```
One of the very nice things about SPICE is that both input and output formats are plain-text, which is the most universal and easy-to-edit electronic format around. Practically any computer will be able to edit and display this format, even if the SPICE program itself is not resident on that computer. If the user desires, he or she is free to use the advanced capabilities of word processing programs to make the output look fancier. Comments can even be inserted between lines of the output for further clarity to the reader.
7.04: The Command-line Interface
If you’ve used DOS or UNIX operating systems before in a command-line shell environment, you may wonder why we have to use the “<” symbol between the word “spice” and the name of the netlist file to be interpreted. Why not just enter the file name as the first argument to the command “spice” as we do when we invoke the text editor? The answer is that SPICE has the option of an interactive mode, whereby each line of the netlist can be interpreted as it is entered through the computer’s Standard Input (stdin). If you simple type “spice” at the prompt and press [Enter], SPICE will begin to interpret anything you type in to it (live).
For most applications, its nice to save your netlist work in a separate file and then let SPICE interpret that file when you’re ready. This is the way I encourage SPICE to be used, and so this is the way its presented in this lesson. In order to use SPICE this way in a command-line environment, we need to use the “<” redirection symbol to direct the contents of your netlist file to Standard Input (stdin), which SPICE can then process | textbooks/workforce/Electronics_Technology/Book%3A_Electric_Circuits_V_-_References_(Kuphaldt)/07%3A_Using_The_spice_Circuit_Simulation_Program/7.03%3A_Fundamentals_of_SPICE_programming.txt |
Remember that this tutorial is not exhaustive by any means, and that all descriptions for elements in the SPICE language are documented here in condensed form. SPICE is a very capable piece of software with lots of options, and I’m only going to document a few of them.
All components in a SPICE source file are primarily identified by the first letter in each respective line. Characters following the identifying letter are used to distinguish one component of a certain type from another of the same type (r1, r2, r3, rload, rpullup, etc.), and need not follow any particular naming convention, so long as no more than eight characters are used in both the component identifying letter and the distinguishing name.
For example, suppose you were simulating a digital circuit with “pullup” and “pulldown” resistors. The name rpullup would be valid because it is seven characters long. The name rpulldown, however, is nine characters long. This may cause problems when SPICE interprets the netlist.
You can actually get away with component names in excess of eight total characters if there are no other similarly-named components in the source file. SPICE only pays attention to the first eight characters of the first field in each line, so rpulldown is actually interpreted as rpulldow with the “n” at the end being ignored. Therefore, any other resistor having the first eight characters in its first field will be seen by SPICE as the same resistor, defined twice, which will cause an error (i.e. rpulldown1 and rpulldown2 would be interpreted as the same name, rpulldow).
It should also be noted that SPICE ignores character case, so r1 and R1 are interpreted by SPICE as one and the same.
SPICE allows the use of metric prefixes in specifying component values, which is a very handy feature. However, the prefix convention used by SPICE differs somewhat from standard metric symbols, primarily due to the fact that netlists are restricted to standard ASCII characters (ruling out Greek letters such as µ for the prefix “micro”) and that SPICE is case-insensitive, so “m” (which is the standard symbol for “milli”) and “M” (which is the standard symbol for “Mega”) are interpreted identically. Here are a few examples of prefixes used in SPICE netlists:
r1 1 0 2t (Resistor R1, 2t = 2 Tera-ohms = 2 TΩ)
r2 1 0 4g (Resistor R2, 4g = 4 Giga-ohms = 4 GΩ)
r3 1 0 47meg (Resistor R3, 47meg = 47 Mega-ohms = 47 MΩ)
r4 1 0 3.3k (Resistor R4, 3.3k = 3.3 kilo-ohms = 3.3 kΩ)
r5 1 0 55m (Resistor R5, 55m = 55 milli-ohms = 55 mΩ)
r6 1 0 10u (Resistor R6, 10u = 10 micro-ohms 10 µΩ)
r7 1 0 30n (Resistor R7, 30n = 30 nano-ohms = 30 nΩ)
r8 1 0 5p (Resistor R8, 5p = 5 pico-ohms = 5 pΩ)
r9 1 0 250f (Resistor R9, 250f = 250 femto-ohms = 250 fΩ)
Scientific notation is also allowed in specifying component values. For example:
r10 1 0 4.7e3 (Resistor R10, 4.7e3 = 4.7 x 103 ohms = 4.7 kilo-ohms = 4.7 kΩ)
r11 1 0 1e-12 (Resistor R11, 1e-12 = 1 x 10-12 ohms = 1 pico-ohm = 1 pΩ)
The unit (ohms, volts, farads, henrys, etc.) is automatically determined by the type of component being specified. SPICE “knows” that all of the above examples are “ohms” because they are all resistors (r1, r2, r3, . . . ). If they were capacitors, the values would be interpreted as “farads,” if inductors, then “henrys,” etc.
Passive components
Capacitors
`General form: c[name] [node1] [node2] [value] ic=[initial voltage] Example 1: c1 12 33 10u Example 2: c1 12 33 10u ic=3.5 `
Comments: The “initial condition” (ic=) variable is the capacitor’s voltage in units of volts at the start of DC analysis. It is an optional value, with the starting voltage assumed to be zero if unspecified. Starting current values for capacitors are interpreted by SPICE only if the .tran analysis option is invoked (with the “uic” option).
INDUCTORS
`General form: l[name] [node1] [node2] [value] ic=[initial current] Example 1: l1 12 33 133m Example 2: l1 12 33 133m ic=12.7m `
Comments: The “initial condition” (ic=) variable is the inductor’s current in units of amps at the start of DC analysis. It is an optional value, with the starting current assumed to be zero if unspecified. Starting current values for inductors are interpreted by SPICE only if the .tran analysis option is invoked.
INDUCTOR COUPLING (transformers)
`General form: k[name] l[name] l[name] [coupling factor] Example 1: k1 l1 l2 0.999 `
Comments: SPICE will only allow coupling factor values between 0 and 1 (non-inclusive), with 0 representing no coupling and 1 representing perfect coupling. The order of specifying coupled inductors (l1, l2 or l2, l1) is irrelevant.
RESISTORS
`General form: r[name] [node1] [node2] [value] Example: rload 23 15 3.3k `
Comments: In case you were wondering, there is no declaration of resistor power dissipation rating in SPICE. All components are assumed to be indestructible. If only real life were this forgiving!
Active components
All semiconductor components must have their electrical characteristics described in a line starting with the word “.model”, which tells SPICE exactly how the device will behave. Whatever parameters are not explicitly defined in the .model card will default to values pre-programmed in SPICE. However, the .modelcard must be included, and at least specify the model name and device type (d, npn, pnp, njf, pjf, nmos, or pmos).
DIODES
`General form: d[name] [anode] [cathode] [model] Example: d1 1 2 mod1 `
DIODE MODELS:
```General form: .model [modelname] d [parmtr1=x] [parmtr2=x] . . . Example: .model mod1 d Example: .model mod2 d vj=0.65 rs=1.3
```
diodeparameter
Parameter definitions:
is = saturation current in amps
rs = junction resistance in ohms
n = emission coefficient (unitless)
tt = transit time in seconds
cjo = zero-bias junction capacitance in farads
vj = junction potential in volts
m = grading coefficient (unitless)
eg = activation energy in electron-volts
xti = saturation-current temperature exponent (unitless)
kf = flicker noise coefficient (unitless)
af = flicker noise exponent (unitless)
fc = forward-bias depletion capacitance coefficient (unitless)
bv = reverse breakdown voltage in volts
ibv = current at breakdown voltage in amps
Comments: The model name must begin with a letter, not a number. If you plan to specify a model for a 1N4003 rectifying diode, for instance, you cannot use “1n4003” for the model name. An alternative might be “m1n4003” instead.
TRANSISTORS, bipolar junction—BJT
`General form: q[name] [collector] [base] [emitter] [model] Example: q1 2 3 0 mod1 `
BJT TRANSISTOR MODELS:
`General form: .model [modelname] [npn or pnp] [parmtr1=x] . . . Example: .model mod1 pnp Example: .model mod2 npn bf=75 is=1e-14 `
The model examples shown above are very nonspecific. To accurately model real-life transistors, more parameters are necessary. Take these two examples, for the popular 2N2222 and 2N2907 transistors (the “+”) characters represent line-continuation marks in SPICE, when you wish to break a single line (card) into two or more separate lines on your text editor:
` Example: .model m2n2222 npn is=19f bf=150 vaf=100 ikf=.18 + ise=50p ne=2.5 br=7.5 var=6.4 ikr=12m + isc=8.7p nc=1.2 rb=50 re=0.4 rc=0.4 cje=26p + tf=0.5n cjc=11p tr=7n xtb=1.5 kf=0.032f af=1 `
`Example: .model m2n2907 pnp is=1.1p bf=200 nf=1.2 vaf=50 + ikf=0.1 ise=13p ne=1.9 br=6 rc=0.6 cje=23p + vje=0.85 mje=1.25 tf=0.5n cjc=19p vjc=0.5 + mjc=0.2 tr=34n xtb=1.5 `
Parameter definitions:
is = transport saturation current in amps
bf = ideal maximum forward Beta (unitless)
nf = forward current emission coefficient (unitless)
vaf = forward Early voltage in volts
ikf = corner for forward Beta high-current rolloff in amps
ise = B-E leakage saturation current in amps
ne = B-E leakage emission coefficient (unitless)
br = ideal maximum reverse Beta (unitless)
nr = reverse current emission coefficient (unitless)
bar = reverse Early voltage in volts
ikrikr = corner for reverse Beta high-current rolloff in amps
iscisc = B-C leakage saturation current in amps
nc = B-C leakage emission coefficient (unitless)
rb = zero bias base resistance in ohms
irb = current for base resistance halfway value in amps
rbm = minimum base resistance at high currents in ohms
re = emitter resistance in ohms
rc = collector resistance in ohms
cje = B-E zero-bias depletion capacitance in farads
vje = B-E built-in potential in volts
mje = B-E junction exponential factor (unitless)
tf = ideal forward transit time (seconds)
xtf = coefficient for bias dependence of transit time (unitless)
vtf = B-C voltage dependence on transit time, in volts
itf = high-current parameter effect on transit time, in amps
ptf = excess phase at f=1/(transit time)(2)(pi) Hz, in degrees
cjc = B-C zero-bias depletion capacitance in farads
vjc = B-C built-in potential in volts
mjc = B-C junction exponential factor (unitless)
xjcj = B-C depletion capacitance fraction connected in base node (unitless)
tr = ideal reverse transit time in seconds
cjs = zero-bias collector-substrate capacitance in farads
vjs = substrate junction built-in potential in volts
mjs = substrate junction exponential factor (unitless)
xtb = forward/reverse Beta temperature exponent
eg = energy gap for temperature effect on transport saturation current in electron-volts
xti = temperature exponent for effect on transport saturation current (unitless)
kf = flicker noise coefficient (unitless)
af = flicker noise exponent (unitless)
fc = forward-bias depletion capacitance formula coefficient (unitless)
Comments: Just as with diodes, the model name given for a particular transistor type must begin with a letter, not a number. That’s why the examples given above for the 2N2222 and 2N2907 types of BJTs are named “m2n2222” and “q2n2907” respectively.
As you can see, SPICE allows for very detailed specification of transistor properties. Many of the properties listed above are well beyond the scope and interest of the beginning electronics student, and aren’t even useful apart from knowing the equations SPICE uses to model BJT transistors. For those interested in learning more about transistor modeling in SPICE, consult other books, such as Andrei Vladimirescu’s The Spice Book (ISBN 0-471-60926-9).
JFET, junction field-effect transistor
`General form: j[name] [drain] [gate] [source] [model] Example: j1 2 3 0 mod1 `
JFET TRANSISTOR MODELS:
`General form: .model [modelname] [njf or pjf] [parmtr1=x] . . . Example: .model mod1 pjf Example: .model mod2 njf lambda=1e-5 pb=0.75 `
Parameter definitions:
vto = threshold voltage in volts
beta = transconductance parameter in amps/volts2
lambda = channel length modulation parameter in units of 1/volts
rd = drain resistance in ohms
rs = source resistance in ohms
cgs = zero-bias G-S junction capacitance in farads
cgd = zero-bias G-D junction capacitance in farads
pb = gate junction potential in volts
is = gate junction saturation current in amps
kf = flicker noise coefficient (unitless)
af = flicker noise exponent (unitless)
fc = forward-bias depletion capacitance coefficient (unitless)
MOSFET, transistor
`General form: m[name] [drain] [gate] [source] [substrate] [model] Example: m1 2 3 0 0 mod1 `
MOSFET TRANSISTOR MODELS:
`General form: .model [modelname] [nmos or pmos] [parmtr1=x] . . . Example: .model mod1 pmos Example: .model mod2 nmos level=2 phi=0.65 rd=1.5 Example: .model mod3 nmos vto=-1 (depletion) Example: .model mod4 nmos vto=1 (enhancement) Example: .model mod5 pmos vto=1 (depletion) Example: .model mod6 pmos vto=-1 (enhancement) `
Comments: In order to distinguish between enhancement mode and depletion-mode (also known as depletion-enhancement mode) transistors, the model parameter “vto” (zero-bias threshold voltage) must be specified. Its default value is zero, but a positive value (+1 volts, for example) on a P-channel transistor or a negative value (-1 volts) on an N-channel transistor will specify that transistor to be a depletion (otherwise known as depletion-enhancement) mode device. Conversely, a negative value on a P-channel transistor or a positive value on an N-channel transistor will specify that transistor to be an enhancement mode device.
Remember that enhancement mode transistors are normally-off devices, and must be turned on by the application of gate voltage. Depletion-mode transistors are normally “on,” but can be “pinched off” as well as enhanced to greater levels of drain current by applied gate voltage, hence the alternate designation of “depletion-enhancement” MOSFETs. The “vto” parameter specifies the threshold gate voltage for MOSFET conduction.
Sources
AC SINEWAVE VOLTAGE SOURCES (when using .ac card to specify frequency):
`General form: v[name] [+node] [-node] ac [voltage] [phase] sin Example 1: v1 1 0 ac 12 sin Example 2: v1 1 0 ac 12 240 sin (12 V ∠ 240o) `
Comments: This method of specifying AC voltage sources works well if you’re using multiple sources at different phase angles from each other, but all at the same frequency. If you need to specify sources at different frequencies in the same circuit, you must use the next method!
AC SINEWAVE VOLTAGE SOURCES (when NOT using .ac card to specify frequency):
`General form: v[name] [+node] [-node] sin([offset] [voltage] + [freq] [delay] [damping factor]) Example 1: v1 1 0 sin(0 12 60 0 0) `
Parameter definitions:
offset = DC bias voltage, offsetting the AC waveform by a specified voltage.
voltage = peak, or crest, AC voltage value for the waveform.
freq = frequency in Hertz.
delay = time delay, or phase offset for the waveform, in seconds.
damping factor = a figure used to create waveforms of decaying amplitude.
Comments: This method of specifying AC voltage sources works well if you’re using multiple sources at different frequencies from each other. Representing phase shift is tricky, though, necessitating the use of the delay factor.
DC VOLTAGE SOURCES (when using .dc card to specify voltage):
`General form: v[name] [+node] [-node] dc Example 1: v1 1 0 dc `
Comments: If you wish to have SPICE output voltages not in reference to node 0, you must use the .dcanalysis option, and to use this option you must specify at least one of your DC sources in this manner.
DC VOLTAGE SOURCES (when NOT using .dc card to specify voltage):
`General form: v[name] [+node] [-node] dc [voltage] Example 1: v1 1 0 dc 12 `
Comments: Nothing noteworthy here!
PULSE VOLTAGE SOURCES
`General form: v[name] [+node] [-node] pulse ( [p] [td] [tr] + [tf] [pw] [pd]) `
Parameter definitions:
i = initial value
p = pulse value
td = delay time (all time parameters in units of seconds)
tr = rise time
tf = fall time
pw = pulse width
pd = period
`Example 1: v1 1 0 pulse (-3 3 0 0 0 10m 20m) `
Comments: Example 1 is a perfect square wave oscillating between -3 and +3 volts, with zero rise and fall times, a 20 millisecond period, and a 50 percent duty cycle (+3 volts for 10 ms, then -3 volts for 10 ms).
AC SINEWAVE CURRENT SOURCES (when using .ac card to specify frequency):
`General form: i[name] [+node] [-node] ac [current] [phase] sin Example 1: i1 1 0 ac 3 sin (3 amps) Example 2: i1 1 0 ac 1m 240 sin (1 mA ∠ 240o) `
Comments: The same comments apply here (and in the next example) as for AC voltage sources.
AC SINEWAVE CURRENT SOURCES (when NOT using .ac card to specify frequency):
`General form: i[name] [+node] [-node] sin([offset] + [current] [freq] 0 0) Example 1: i1 1 0 sin(0 1.5 60 0 0) `
DC CURRENT SOURCES (when using .dc card to specify current):
`General form: i[name] [+node] [-node] dc Example 1: i1 1 0 dc `
DC CURRENT SOURCES (when NOT using .dc card to specify current):
`General form: i[name] [+node] [-node] dc [current] Example 1: i1 1 0 dc 12 `
Comments: Even though the books all say that the first node given for the DC current source is the positive node, that’s not what I’ve found to be in practice. In actuality, a DC current source in SPICE pushes current in the same direction as a voltage source (battery) would with its negative node specified first.
PULSE CURRENT SOURCES
`General form: i[name] [+node] [-node] pulse ( [p] [td] [tr] + [tf] [pw] [pd]) `
Parameter definitions:
i = initial value
p = pulse value
td = delay time
tr = rise time
tf = fall time
pw = pulse width
pd = period
`Example 1: i1 1 0 pulse (-3m 3m 0 0 0 17m 34m) `
Comments: Example 1 is a perfect square wave oscillating between -3 mA and +3 mA, with zero rise and fall times, a 34 millisecond period, and a 50 percent duty cycle (+3 mA for 17 ms, then -3 mA for 17 ms).
VOLTAGE SOURCES (dependent):
`General form: e[name] [out+node] [out-node] [in+node] [in-node] + [gain] Example 1: e1 2 0 1 2 999k `
Comments: Dependent voltage sources are great to use for simulating operational amplifiers. Example 1 shows how such a source would be configured for use as a voltage follower, inverting input connected to output (node 2) for negative feedback, and the noninverting input coming in on node 1. The gain has been set to an arbitrarily high value of 999,000. One word of caution, though: SPICE does not recognize the input of a dependent source as being a load, so a voltage source tied only to the input of an independent voltage source will be interpreted as “open.” See op-amp circuit examples for more details on this.
CURRENT SOURCES (dependent): | textbooks/workforce/Electronics_Technology/Book%3A_Electric_Circuits_V_-_References_(Kuphaldt)/07%3A_Using_The_spice_Circuit_Simulation_Program/7.05%3A_Circuit_Components.txt |
AC ANALYSIS:
`General form: .ac [curve] [points] [start] [final] Example 1: .ac lin 1 1000 1000 `
Comments: The [curve] field can be “lin” (linear), “dec” (decade), or “oct” (octave), specifying the (non)linearity of the frequency sweep. specifies how many points within the frequency sweep to perform analyses at (for decade sweep, the number of points per decade; for octave, the number of points per octave). The [start] and [final] fields specify the starting and ending frequencies of the sweep, respectively. One final note: the “start” value cannot be zero!
DC ANALYSIS:
`General form: .dc [source] [start] [final] [increment] Example 1: .dc vin 1.5 15 0.5 `
Comments: The .dc card is necessary if you want to print or plot any voltage between two nonzero nodes. Otherwise, the default “small-signal” analysis only prints out the voltage between each nonzero node and node zero.
TRANSIENT ANALYSIS:
`General form: .tran [increment] [stop_time] [start_time] + [comp_interval] Example 1: .tran 1m 50m uic Example 2: .tran .5m 32m 0 .01m `
Comments: Example 1 has an increment time of 1 millisecond and a stop time of 50 milliseconds (when only two parameters are specified, they are increment time and stop time, respectively). Example 2 has an increment time of 0.5 milliseconds, a stop time of 32 milliseconds, a start time of 0 milliseconds (no delay on start), and a computation interval of 0.01 milliseconds.
Default value for start time is zero. Transient analysis always beings at time zero, but storage of data only takes place between start time and stop time. Data output interval is increment time, or (stop time - start time)/50, which ever is smallest. However, the computing interval variable can be used to force a computational interval smaller than either. For large total interval counts, the itl5 variable in the .optionscard may be set to a higher number. The “uic” option tells SPICE to “use initial conditions.”
PLOT OUTPUT:
`General form: .plot [type] [output1] [output2] . . . [output n] Example 1: .plot dc v(1,2) i(v2) Example 2: .plot ac v(3,4) vp(3,4) i(v1) ip(v1) Example 3: .plot tran v(4,5) i(v2) `
Comments: SPICE can’t handle more than eight data point requests on a single .plot or .print card. If requesting more than eight data points, use multiple cards!
Also, here’s a major caveat when using SPICE version 3: if you’re performing AC analysis and you ask SPICE to plot an AC voltage as in example #2, the v(3,4) command will only output the real component of a rectangular-form complex number! SPICE version 2 outputs the polar magnitude of a complex number: a much more meaningful quantity if only a single quantity is asked for. To coerce SPICE3 to give you polar magnitude, you will have to re-write the .print or .plot argument as such: vm(3,4).
PRINT OUTPUT:
`General form: .print [type] [output1] [output2] . . . [output n] Example 1: .print dc v(1,2) i(v2) Example 2: .print ac v(2,4) i(vinput) vp(2,3) Example 3: .print tran v(4,5) i(v2) `
Comments: SPICE can’t handle more than eight data point requests on a single .plot or .print card. If requesting more than eight data points, use multiple cards!
FOURIER ANALYSIS:
`General form: .four [freq] [output1] [output2] . . . [output n] Example 1: .four 60 v(1,2) `
Comments: The .four card relies on the .tran card being present somewhere in the deck, with the proper time periods for analysis of adequate cycles. Also, SPICE may “crash” if a .plot analysis isn’t done along with the .four analysis, even if all .tran parameters are technically correct. Finally, the .four analysis option only works when the frequency of the AC source is specified in that source’s card line, and not in an .ac analysis option line.
It helps to include a computation interval variable in the .tran card for better analysis precision. A Fourier analysis of the voltage or current specified is performed up to the 9th harmonic, with the [freq] specification being the fundamental, or starting frequency of the analysis spectrum.
MISCELLANEOUS:
`General form: .options [option1] [option2] Example 1: .options limpts=500 Example 2: .options itl5=0 Example 3: .options method=gear Example 4: .options list Example 5: .options nopage Example 6: .options numdgt=6 `
Comments: There are lots of options that can be specified using this card. Perhaps the one most needed by beginning users of SPICE is the “limpts” setting. When running a simulation that requires more than 201 points to be printed or plotted, this calculation point limit must be increased or else SPICE will terminate analysis. The example given above (limpts=500) tells SPICE to allocate enough memory to handle at least 500 calculation points in whatever type of analysis is specified (DC, AC, or transient).
In example 2, we see an iteration variable (itl5) being set to a value of 0. There are actually six different iteration variables available for user manipulation. They control the iteration cycle limits for solution of nonlinear equations. The variable itl5 sets the maximum number of iterations for a transient analysis. Similar to the limpts variable, itl5 usually needs to be set when a small computation interval has been specified on a .tran card. Setting itl5 to a value of 0 turns off the limit entirely, allowing the computer infinite iteration cycles (infinite time) to compute the analysis. Warning: this may result in long simulation times!
Example 3 with “method=gear” sets the numerical integration method used by SPICE. The default is “trapezoid” rather than “gear,” trapezoid being a simple geometric approximation of area under a curve found by slicing up the curve into trapezoids to approximate the shape. The “gear” method is based on second-order or better polynomial equations and is named after C.W. Gear (Numerical Integration of Stiff Ordinary Equations, Report 221, Department of Computer Science, University of Illinois, Urbana). The Gear method of integration is more demanding of the computer (computationally “expensive”) and will sometimes give slightly different results from the trapezoid method.
The “list” option shown in example 4 gives a verbose summary of all circuit components and their respective values in the final output.
By default, SPICE will insert ASCII page-break control codes in the output to separate different sections of the analysis. Specifying the “nopage” option (example 5) will prevent such pagination.
The “numdgt” option shown in example 6 specifies the number of significant digits output when using one of the “.print” data output options. SPICE defaults at a precision of 4 significant digits.
WIDTH CONTROL:
`General form: .width in=[columns] out=[columns] Example 1: .width out=80 ` | textbooks/workforce/Electronics_Technology/Book%3A_Electric_Circuits_V_-_References_(Kuphaldt)/07%3A_Using_The_spice_Circuit_Simulation_Program/7.06%3A_Analysis_Options.txt |
“Garbage in, garbage out.”
—Anonymous
SPICE is a very reliable piece of software, but it does have its little quirks that take some getting used to. By “quirk” I mean a demand placed upon the user to write the source file in a particular way in order for it to work without giving error messages. I do not mean any kind of fault with SPICE which would produce erroneous or misleading results: that would be more properly referred to as a “bug.” Speaking of bugs, SPICE has a few of them as well.
Some (or all) of these quirks may be unique to SPICE version 2g6, which is the only version I’ve used extensively. They may have been fixed in later versions.
A good beginning
SPICE demands that the source file begins with something other than the first “card” in the circuit description “deck.” This first character in the source file can be a linefeed, title line, or a comment: there just has to be something there before the first component-specifying line of the file. If not, SPICE will refuse to do an analysis at all, claiming that there is a serious error (such as improper node connections) in the “deck.”
A good ending
SPICE demands that the .end line at the end of the source file not be terminated with a linefeed or carriage return character. In other words, when you finish typing “.end” you should not hit the [Enter] key on your keyboard. The cursor on your text editor should stop immediately to the right of the “d” after the “.end” and go no further. Failure to heed this quirk will result in a “missing .end card” error message at the end of the analysis output. The actual circuit analysis is not affected by this error, so I normally ignore the message. However, if you’re looking to receive a “perfect” output, you must pay heed to this idiosyncrasy.
Must have a node 0
You are given much freedom in numbering circuit nodes, but you must have a node 0 somewhere in your netlist in order for SPICE to work. Node 0 is the default node for circuit ground, and it is the point of reference for all voltages specified at single node locations.
When simple DC analysis is performed by SPICE, the output will contain a listing of voltages at all non-zero nodes in the circuit. The point of reference (ground) for all these voltage readings is node 0. For example:
```node voltage node voltage ( 1) 15.0000 ( 2) 0.6522
```
In this analysis, there is a DC voltage of 15 volts between node 1 and ground (node 0), and a DC voltage of 0.6522 volts between node 2 and ground (node 0). In both these cases, the voltage polarity is negative at node 0 with reference to the other node (in other words, both nodes 1 and 2 are positive with respect to node 0).
Avoid open circuits
SPICE cannot handle open circuits of any kind. If your netlist specifies a circuit with an open voltage source, for example, SPICE will refuse to perform an analysis. A prime example of this type of error is found when “connecting” a voltage source to the input of a voltage-dependent source (used to simulate an operational amplifier). SPICE needs to see a complete path for current, so I usually tie a high-value resistor (call it rbogus!) across the voltage source to act as a minimal load.
Avoid certain component loops
SPICE cannot handle certain uninterrupted loops of components in a circuit, namely voltage sources and inductors. The following loops will cause SPICE to abort analysis:
`netlist l1 2 4 10m l2 2 4 50m l3 2 4 25m `
`netlist v1 1 0 dc 12 l1 1 0 150m `
`netlist c1 5 6 33u c2 6 7 47u `
The reason SPICE can’t handle these conditions stems from the way it performs DC analysis: by treating all inductors as shorts and all capacitors as opens. Since short-circuits (0 Ω) and open circuits (infinite resistance) either contain or generate mathematical infinitudes, a computer simply cannot deal with them, and so SPICE will discontinue analysis if any of these conditions occur.
In order to make these component configurations acceptable to SPICE, you must insert resistors of appropriate values into the appropriate places, eliminating the respective short-circuits and open-circuits. If a series resistor is required, choose a very low resistance value. Conversely, if a parallel resistor is required, choose a very high resistance value. For example:
To fix the parallel inductor problem, insert a very low-value resistor in series with each offending inductor.
`original netlist l1 2 4 10m l2 2 4 50m l3 2 4 25m `
`fixed netlist rbogus1 2 3 1e-12 rbogus2 2 5 1e-12 l1 3 4 10m l2 2 4 50m l3 5 4 25m `
The extremely low-resistance resistors Rbogus1 and Rbogus2 (each one with a mere 1 pico-ohm of resistance) “break up” the direct parallel connections that existed between L1, L2, and L3. It is important to choose very low resistances here so that circuit operation is not substantially impacted by the “fix.”
To fix the voltage source / inductor loop, insert a very low-value resistor in series with the two components.
`original netlist v1 1 0 dc 12 l1 1 0 150m `
`fixed netlist v1 1 0 dc 12 l1 2 0 150m rbogus 1 2 1e-12 `
As in the previous example with parallel inductors, it is important to make the correction resistor (Rbogus) very low in resistance, so as to not substantially impact circuit operation.
To fix the series capacitor circuit, one of the capacitors must have a resistor shunting across it. SPICE requires a DC current path to each capacitor for analysis.
`original netlist c1 5 6 33u c2 6 7 47u `
`fixed netlist c1 5 6 33u c2 6 7 47u rbogus 6 7 9e12 `
The Rbogus value of 9 Tera-ohms provides a DC current path to C1 (and around C2) without substantially impacting the circuit’s operation.
Current measurement
Although printing or plotting of voltage is quite easy in SPICE, the output of current values is a bit more difficult. Voltage measurements are specified by declaring the appropriate circuit nodes. For example, if we desire to know the voltage across a capacitor whose leads connect between nodes 4 and 7, we might make out .print statement look like this:
`c1 4 7 22u .print ac v(4,7) `
However, if we wanted to have SPICE measure the current through that capacitor, it wouldn’t be quite so easy. Currents in SPICE must be specified in relation to a voltage source, not any arbitrary component. For example:
`c1 4 7 22u vinput 6 4 ac 1 sin .print ac i(vinput) `
This .print card instructs SPICE to print the current through voltage source Vinput, which happens to be the same as the current through our capacitor between nodes 4 and 7. But what if there is no such voltage source in our circuit to reference for current measurement? One solution is to insert a shunt resistor into the circuit and measure voltage across it. In this case, I have chosen a shunt resistance value of 1 Ω to produce 1 volt per amp of current through C1:
`c1 4 7 22u rshunt 6 4 1 .print ac v(6,4) `
However, the insertion of an extra resistance into our circuit large enough to drop a meaningful voltage for the intended range of current might adversely affect things. A better solution for SPICE is this, although one would never seek such a current measurement solution in real life:
`c1 4 7 22u vbogus 6 4 dc 0 .print ac i(vbogus) `
Inserting a “bogus” DC voltage source of zero volts doesn’t affect circuit operation at all, yet it provides a convenient place for SPICE to take a current measurement. Interestingly enough, it doesn’t matter that Vbogus is a DC source when we’re looking to measure AC current! The fact that SPICE will output an AC current reading is determined by the “ac” specification in the .print card and nothing more.
It should also be noted that the way SPICE assigns a polarity to current measurements is a bit odd. Take the following circuit as an example:
`example v1 1 0 r1 1 2 5k r2 2 0 5k .dc v1 10 10 1 .print dc i(v1) .end `
With 10 volts total voltage and 10 kΩ total resistance, you might expect SPICE to tell you there’s going to be 1 mA (1e-03) of current through voltage source V1, but in actuality, SPICE will output a figure of negative 1 mA (-1e-03)! SPICE regards current out of the negative end of a DC voltage source (the normal direction) to be a negative value of current rather than a positive value of current. There are times I’ll throw in a “bogus” voltage source in a DC circuit like this simply to get SPICE to output a positive current value:
`example v1 1 0 r1 1 2 5k r2 2 3 5k vbogus 3 0 dc 0 .dc v1 10 10 1 .print dc i(vbogus) .end `
Notice how Vbogus is positioned so that the circuit current will enter its positive side (node 3) and exit its negative side (node 0). This orientation will ensure a positive output figure for circuit current.
Fourier analysis
When performing a Fourier (frequency-domain) analysis on a waveform, I have found it necessary to either print or plot the waveform using the .print or .plot cards, respectively. If you don’t print or plot it, SPICE will pause for a moment during analysis and then abort the job after outputting the “initial transient solution.”
Also, when analyzing a square wave produced by the “pulse” source function, you must give the waveform some finite rise and fall time, or else the Fourier analysis results will be incorrect. For some reason, a perfect square wave with zero rise/fall time produces significant levels of even harmonics according to SPICE’s Fourier analysis option, which is not true for real square waves. | textbooks/workforce/Electronics_Technology/Book%3A_Electric_Circuits_V_-_References_(Kuphaldt)/07%3A_Using_The_spice_Circuit_Simulation_Program/7.07%3A_SPICE_Quirks.txt |
The following circuits are pre-tested netlists for SPICE 2g6, complete with short descriptions when necessary. (See Chapter 2’s Computer Simulation of Electric Circuits for more information on netlists in SPICE.)
Feel free to “copy” and “paste” any of the netlists to your own SPICE source file for analysis and/or modification.
My goal here is twofold: to give practical examples of SPICE netlist design to further understanding of SPICE netlist syntax, and to show how simple and compact SPICE netlists can be in analyzing simple circuits.
All output listings for these examples have been “trimmed” of extraneous information, giving you the most succinct presentation of the SPICE output as possible. I do this primarily to save space in this document. Typical SPICE outputs contain lots of headers and summary information not necessarily germane to the task at hand. So don’t be surprised when you run a simulation on your own and find that the output doesn’t exactly look like what I have shown here!
Example multiple-source DC resistor network circuit, part 1
Without a .dc card and a .print or .plot card, the output for this netlist will only display voltages for nodes 1, 2, and 3 (with reference to node 0, of course).
Netlist:
```Multiple dc sources v1 1 0 dc 24 v2 3 0 dc 15 r1 1 2 10k r2 2 3 8.1k r3 2 0 4.7k .end
```
Output:
```node voltage node voltage node voltage ( 1) 24.0000 ( 2) 9.7470 ( 3) 15.0000
```
`voltage source currents name current v1 -1.425E-03 v2 -6.485E-04 `
```total power dissipation 4.39E-02 watts
```
Example multiple-source DC resistor network circuit, part 2
By adding a .dc analysis card and specifying source V1 from 24 volts to 24 volts in 1 step (in other words, 24 volts steady), we can use the .print card analysis to print out voltages between any two points we desire. Oddly enough, when the .dc analysis option is invoked, the default voltage printouts for each node (to ground) disappears, so we end up having to explicitly specify them in the .print card to see them at all.
Netlist:
```Multiple dc sources v1 1 0 v2 3 0 15 r1 1 2 10k r2 2 3 8.1k r3 2 0 4.7k .dc v1 24 24 1 .print dc v(1) v(2) v(3) v(1,2) v(2,3) .end
```
Output:
`v1 v(1) v(2) v(3) v(1,2) v(2,3) 2.400E+01 2.400E+01 9.747E+00 1.500E+01 1.425E+01 -5.253E+00 `
Example RC time-constant circuit
For DC analysis, the initial conditions of any reactive component (C or L) must be specified (voltage for capacitors, current for inductors). This is provided by the last data field of each capacitor card (ic=0). To perform a DC analysis, the .tran (”transient”) analysis option must be specified, with the first data field specifying time increment in seconds, the second specifying total analysis timespan in seconds, and the “uic” telling it to “use initial conditions” when analyzing.
Netlist:
```RC time delay circuit v1 1 0 dc 10 c1 1 2 47u ic=0 c2 1 2 22u ic=0 r1 2 0 3.3k .tran .05 1 uic .print tran v(1,2) .end
```
Output:
`time v(1,2) 0.000E+00 7.701E-06 5.000E-02 1.967E+00 1.000E-01 3.551E+00 1.500E-01 4.824E+00 2.000E-01 5.844E+00 2.500E-01 6.664E+00 3.000E-01 7.322E+00 3.500E-01 7.851E+00 4.000E-01 8.274E+00 4.500E-01 8.615E+00 5.000E-01 8.888E+00 5.500E-01 9.107E+00 6.000E-01 9.283E+00 6.500E-01 9.425E+00 7.000E-01 9.538E+00 7.500E-01 9.629E+00 8.000E-01 9.702E+00 8.500E-01 9.761E+00 9.000E-01 9.808E+00 9.500E-01 9.846E+00 1.000E+00 9.877E+00 `
Plotting and analyzing a simple AC sinewave voltage circuit
This exercise does show the proper setup for plotting instantaneous values of a sine-wave voltage source with the .plot function (as a transient analysis). Not surprisingly, the Fourier analysis in this deck also requires the .tran (transient) analysis option to be specified over a suitable time range. The time range in this particular deck allows for a Fourier analysis with rather poor accuracy. The more cycles of the fundamental frequency that the transient analysis is performed over, the more precise the Fourier analysis will be. This is not a quirk of SPICE, but rather a basic principle of waveforms.
Netlist:
`v1 1 0 sin(0 15 60 0 0) rload 1 0 10k * change tran card to the following for better Fourier precision * .tran 1m 30m .01m and include .options card: * .options itl5=30000 .tran 1m 30m .plot tran v(1) .four 60 v(1) .end `
Output:
`time v(1) -2.000E+01 -1.000E+01 0.000E+00 1.000E+01 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 0.000E+00 0.000E+00 . . * . . 1.000E-03 5.487E+00 . . . * . . 2.000E-03 1.025E+01 . . . * . 3.000E-03 1.350E+01 . . . . * . 4.000E-03 1.488E+01 . . . . *. 5.000E-03 1.425E+01 . . . . * . 6.000E-03 1.150E+01 . . . . * . 7.000E-03 7.184E+00 . . . * . . 8.000E-03 1.879E+00 . . . * . . 9.000E-03 -3.714E+00 . . * . . . 1.000E-02 -8.762E+00 . . * . . . 1.100E-02 -1.265E+01 . * . . . . 1.200E-02 -1.466E+01 . * . . . . 1.300E-02 -1.465E+01 . * . . . . 1.400E-02 -1.265E+01 . * . . . . 1.500E-02 -8.769E+00 . . * . . . 1.600E-02 -3.709E+00 . . * . . . 1.700E-02 1.876E+00 . . . * . . 1.800E-02 7.191E+00 . . . * . . 1.900E-02 1.149E+01 . . . . * . 2.000E-02 1.425E+01 . . . . * . 2.100E-02 1.489E+01 . . . . *. 2.200E-02 1.349E+01 . . . . * . 2.300E-02 1.026E+01 . . . * . 2.400E-02 5.491E+00 . . . * . . 2.500E-02 1.553E-03 . . * . . 2.600E-02 -5.514E+00 . . * . . . 2.700E-02 -1.022E+01 . * . . . 2.800E-02 -1.349E+01 . * . . . . 2.900E-02 -1.495E+01 . * . . . . 3.000E-02 -1.427E+01 . * . . . . - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - `
` fourier components of transient response v(1) dc component = -1.885E-03 harmonic frequency fourier normalized phase normalized no (hz) component component (deg) phase (deg) 1 6.000E+01 1.494E+01 1.000000 -71.998 0.000 2 1.200E+02 1.886E-02 0.001262 -50.162 21.836 3 1.800E+02 1.346E-03 0.000090 102.674 174.671 4 2.400E+02 1.799E-02 0.001204 -10.866 61.132 5 3.000E+02 3.604E-03 0.000241 160.923 232.921 6 3.600E+02 5.642E-03 0.000378 -176.247 -104.250 7 4.200E+02 2.095E-03 0.000140 122.661 194.658 8 4.800E+02 4.574E-03 0.000306 -143.754 -71.757 9 5.400E+02 4.896E-03 0.000328 -129.418 -57.420 total harmonic distortion = 0.186350 percent `
Example simple AC resistor-capacitor circuit
The .ac card specifies the points of ac analysis from 60Hz to 60Hz, at a single point. This card, of course, is a bit more useful for multi-frequency analysis, where a range of frequencies can be analyzed in steps. The .print card outputs the AC voltage between nodes 1 and 2, and the AC voltage between node 2 and ground.
Netlist:
`Demo of a simple AC circuit v1 1 0 ac 12 sin r1 1 2 30 c1 2 0 100u .ac lin 1 60 60 .print ac v(1,2) v(2) .end `
Output:
`freq v(1,2) v(2) 6.000E+01 8.990E+00 7.949E+00 `
Example low-pass filter circuit
This low-pass filter blocks AC and passes DC to the Rload resistor. Typical of a filter used to suppress ripple from a rectifier circuit, it actually has a resonant frequency, technically making it a band-pass filter. However, it works well anyway to pass DC and block the high-frequency harmonics generated by the AC-to-DC rectification process. Its performance is measured with an AC source sweeping from 500 Hz to 15 kHz. If desired, the .print card can be substituted or supplemented with a .plot card to show AC voltage at node 4 graphically.
Netlist:
`Lowpass filter v1 2 1 ac 24 sin v2 1 0 dc 24 rload 4 0 1k l1 2 3 100m l2 3 4 250m c1 3 0 100u .ac lin 30 500 15k .print ac v(4) .plot ac v(4) .end `
`freq v(4) 5.000E+02 1.935E-01 1.000E+03 3.275E-02 1.500E+03 1.057E-02 2.000E+03 4.614E-03 2.500E+03 2.402E-03 3.000E+03 1.403E-03 3.500E+03 8.884E-04 4.000E+03 5.973E-04 4.500E+03 4.206E-04 5.000E+03 3.072E-04 5.500E+03 2.311E-04 6.000E+03 1.782E-04 6.500E+03 1.403E-04 7.000E+03 1.124E-04 7.500E+03 9.141E-05 8.000E+03 7.536E-05 8.500E+03 6.285E-05 9.000E+03 5.296E-05 9.500E+03 4.504E-05 1.000E+04 3.863E-05 1.050E+04 3.337E-05 1.100E+04 2.903E-05 1.150E+04 2.541E-05 1.200E+04 2.237E-05 1.250E+04 1.979E-05 1.300E+04 1.760E-05 1.350E+04 1.571E-05 1.400E+04 1.409E-05 1.450E+04 1.268E-05 1.500E+04 1.146E-05 `
`freq v(4) 1.000E-06 1.000E-04 1.000E-02 1.000E+00 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 5.000E+02 1.935E-01 . . . * . 1.000E+03 3.275E-02 . . . * . 1.500E+03 1.057E-02 . . * . 2.000E+03 4.614E-03 . . * . . 2.500E+03 2.402E-03 . . * . . 3.000E+03 1.403E-03 . . * . . 3.500E+03 8.884E-04 . . * . . 4.000E+03 5.973E-04 . . * . . 4.500E+03 4.206E-04 . . * . . 5.000E+03 3.072E-04 . . * . . 5.500E+03 2.311E-04 . . * . . 6.000E+03 1.782E-04 . . * . . 6.500E+03 1.403E-04 . .* . . 7.000E+03 1.124E-04 . * . . 7.500E+03 9.141E-05 . * . . 8.000E+03 7.536E-05 . *. . . 8.500E+03 6.285E-05 . *. . . 9.000E+03 5.296E-05 . * . . . 9.500E+03 4.504E-05 . * . . . 1.000E+04 3.863E-05 . * . . . 1.050E+04 3.337E-05 . * . . . 1.100E+04 2.903E-05 . * . . . 1.150E+04 2.541E-05 . * . . . 1.200E+04 2.237E-05 . * . . . 1.250E+04 1.979E-05 . * . . . 1.300E+04 1.760E-05 . * . . . 1.350E+04 1.571E-05 . * . . . 1.400E+04 1.409E-05 . * . . . 1.450E+04 1.268E-05 . * . . . 1.500E+04 1.146E-05 . * . . . - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - `
Example multiple-source AC network circuit
One of the idiosyncrasies of SPICE is its inability to handle any loop in a circuit exclusively composed of series voltage sources and inductors. Therefore, the “loop” of V1-L1-L2-V2-V1 is unacceptable. To get around this, I had to insert a low-resistance resistor somewhere in that loop to break it up. Thus, we have Rbogusbetween 3 and 4 (with 1 pico-ohm of resistance), and V2 between 4 and 0. The circuit above is the original design, while the circuit below has Rbogus inserted to avoid the SPICE error.
Netlist:
`Multiple ac source v1 1 0 ac 55 0 sin v2 4 0 ac 43 25 sin l1 1 2 450m c1 2 0 330u l2 2 3 150m rbogus 3 4 1e-12 .ac lin 1 30 30 .print ac v(2) .end `
Output:
`freq v(2) 3.000E+01 1.413E+02 `
Example AC phase shift demonstration circuit
The currents through each leg are indicated by the voltage drops across each respective shunt resistor (1 amp = 1 volt through 1 Ω), output by the v(1,2) and v(1,3) terms of the .print card. The phase of the currents through each leg are indicated by the phase of the voltage drops across each respective shunt resistor, output by the vp(1,2) and vp(1,3) terms in the .print card.
Netlist:
`phase shift v1 1 0 ac 4 sin rshunt1 1 2 1 rshunt2 1 3 1 l1 2 0 1 r1 3 0 6.3k .ac lin 1 1000 1000 .print ac v(1,2) v(1,3) vp(1,2) vp(1,3) .end `
Output:
`freq v(1,2) v(1,3) vp(1,2) vp(1,3) 1.000E+03 6.366E-04 6.349E-04 -9.000E+01 0.000E+00 `
Example transformer circuit
SPICE understands transformers as a set of mutually coupled inductors. Thus, to simulate a transformer in SPICE, you must specify the primary and secondary windings as separate inductors, then instruct SPICE to link them together with a “k” card specifying the coupling constant. For ideal transformer simulation, the coupling constant would be unity (1). However, SPICE can’t handle this value, so we use something like 0.999 as the coupling factor.
Note that all winding inductor pairs must be coupled with their own k cards in order for the simulation to work properly. For a two-winding transformer, a single k card will suffice. For a three-winding transformer, three k cards must be specified (to link L1 with L2, L2 with L3, and L1 with L3).
The L1/L2 inductance ratio of 100:1 provides a 10:1 step-down voltage transformation ratio. With 120 volts in we should see 12 volts out of the L2 winding. The L1/L3 inductance ratio of 100:25 (4:1) provides a 2:1 step-down voltage transformation ratio, which should give us 60 volts out of the L3 winding with 120 volts in.
Netlist:
`transformer v1 1 0 ac 120 sin rbogus0 1 6 1e-3 l1 6 0 100 l2 2 4 1 l3 3 5 25 k1 l1 l2 0.999 k2 l2 l3 0.999 k3 l1 l3 0.999 r1 2 4 1000 r2 3 5 1000 rbogus1 5 0 1e10 rbogus2 4 0 1e10 .ac lin 1 60 60 .print ac v(1,0) v(2,0) v(3,0) .end `
Output:
`freq v(1) v(2) v(3) 6.000E+01 1.200E+02 1.199E+01 5.993E+01 `
In this example, Rbogus0 is a very low-value resistor, serving to break up the source/inductor loop of V1/L1. Rbogus1 and Rbogus2 are very high-value resistors necessary to provide DC paths to a ground on each of the isolated circuits. Note as well that one side of the primary circuit is directly grounded. Without these ground references, SPICE will produce errors!
Example full-wave bridge rectifier circuit
Diodes, like all semiconductor components in SPICE, must be modeled so that SPICE knows all the nitty-gritty details of how they’re supposed to work. Fortunately, SPICE comes with a few generic models, and the diode is the most basic. Notice the .model card which simply specifies “d” as the generic diode model for mod1. Again, since we’re plotting the waveforms here, we need to specify all parameters of the AC source in a single card and print/plot all values using the .tran option.
Netlist:
`fullwave bridge rectifier v1 1 0 sin(0 15 60 0 0) rload 1 0 10k d1 1 2 mod1 d2 0 2 mod1 d3 3 1 mod1 d4 3 0 mod1 .model mod1 d .tran .5m 25m .plot tran v(1,0) v(2,3) .end `
Output:
`legend: *: v(1) +: v(2,3) time v(1) (*)--------- -2.000E+01 -1.000E+01 0.000E+00 1.000E+01 2.000E+01 (+)--------- -5.000E+00 0.000E+00 5.000E+00 1.000E+01 1.500E+01 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 0.000E+00 0.000E+00 . + * . . 5.000E-04 2.806E+00 . . + . * . . 1.000E-03 5.483E+00 . . + * . . 1.500E-03 7.929E+00 . . . + * . . 2.000E-03 1.013E+01 . . . +* . 2.500E-03 1.198E+01 . . . . * + . 3.000E-03 1.338E+01 . . . . * + . 3.500E-03 1.435E+01 . . . . * +. 4.000E-03 1.476E+01 . . . . * + 4.500E-03 1.470E+01 . . . . * + 5.000E-03 1.406E+01 . . . . * + . 5.500E-03 1.299E+01 . . . . * + . 6.000E-03 1.139E+01 . . . . *+ . 6.500E-03 9.455E+00 . . . + *. . 7.000E-03 7.113E+00 . . . + * . . 7.500E-03 4.591E+00 . . +. * . . 8.000E-03 1.841E+00 . . + . * . . 8.500E-03 -9.177E-01 . . + *. . . 9.000E-03 -3.689E+00 . . *+ . . . 9.500E-03 -6.380E+00 . . * . + . . 1.000E-02 -8.784E+00 . . * . + . . 1.050E-02 -1.075E+01 . *. . .+ . 1.100E-02 -1.255E+01 . * . . . + . 1.150E-02 -1.372E+01 . * . . . + . 1.200E-02 -1.460E+01 . * . . . + 1.250E-02 -1.476E+01 .* . . . + 1.300E-02 -1.460E+01 . * . . . + 1.350E-02 -1.373E+01 . * . . . + . 1.400E-02 -1.254E+01 . * . . . + . 1.450E-02 -1.077E+01 . *. . .+ . 1.500E-02 -8.726E+00 . . * . + . . 1.550E-02 -6.293E+00 . . * . + . . 1.600E-02 -3.684E+00 . . x . . . 1.650E-02 -9.361E-01 . . + *. . . 1.700E-02 1.875E+00 . . + . * . . 1.750E-02 4.552E+00 . . +. * . . 1.800E-02 7.170E+00 . . . + * . . 1.850E-02 9.401E+00 . . . + *. . 1.900E-02 1.146E+01 . . . . *+ . 1.950E-02 1.293E+01 . . . . * + . 2.000E-02 1.414E+01 . . . . * +. 2.050E-02 1.464E+01 . . . . * + 2.100E-02 1.483E+01 . . . . * + 2.150E-02 1.430E+01 . . . . * +. 2.200E-02 1.344E+01 . . . . * + . 2.250E-02 1.195E+01 . . . . *+ . 2.300E-02 1.016E+01 . . . +* . 2.350E-02 7.917E+00 . . . + * . . 2.400E-02 5.460E+00 . . + * . . 2.450E-02 2.809E+00 . . + . * . . 2.500E-02 -8.297E-04 . + * . . - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - `
Example common-base BJT transistor amplifier circuit
This analysis sweeps the input voltage (Vin) from 0 to 5 volts in 0.1 volt increments, then prints out the voltage between the collector and emitter leads of the transistor v(2,3). The transistor (Q1) is an NPN with a forward Beta of 50.
Netlist:
`Common-base BJT amplifier vsupply 1 0 dc 24 vin 0 4 dc rc 1 2 800 re 3 4 100 q1 2 0 3 mod1 .model mod1 npn bf=50 .dc vin 0 5 0.1 .print dc v(2,3) .plot dc v(2,3) .end `
Output:
`vin v(2,3) 0.000E+00 2.400E+01 1.000E-01 2.410E+01 2.000E-01 2.420E+01 3.000E-01 2.430E+01 4.000E-01 2.440E+01 5.000E-01 2.450E+01 6.000E-01 2.460E+01 7.000E-01 2.466E+01 8.000E-01 2.439E+01 9.000E-01 2.383E+01 1.000E+00 2.317E+01 1.100E+00 2.246E+01 1.200E+00 2.174E+01 1.300E+00 2.101E+01 1.400E+00 2.026E+01 1.500E+00 1.951E+01 1.600E+00 1.876E+01 1.700E+00 1.800E+01 1.800E+00 1.724E+01 1.900E+00 1.648E+01 2.000E+00 1.572E+01 2.100E+00 1.495E+01 2.200E+00 1.418E+01 2.300E+00 1.342E+01 2.400E+00 1.265E+01 2.500E+00 1.188E+01 2.600E+00 1.110E+01 2.700E+00 1.033E+01 2.800E+00 9.560E+00 2.900E+00 8.787E+00 3.000E+00 8.014E+00 3.100E+00 7.240E+00 3.200E+00 6.465E+00 3.300E+00 5.691E+00 3.400E+00 4.915E+00 3.500E+00 4.140E+00 3.600E+00 3.364E+00 3.700E+00 2.588E+00 3.800E+00 1.811E+00 3.900E+00 1.034E+00 4.000E+00 2.587E-01 4.100E+00 9.744E-02 4.200E+00 7.815E-02 4.300E+00 6.806E-02 4.400E+00 6.141E-02 4.500E+00 5.657E-02 4.600E+00 5.281E-02 4.700E+00 4.981E-02 4.800E+00 4.734E-02 4.900E+00 4.525E-02 5.000E+00 4.346E-02 `
`vin v(2,3) 0.000E+00 1.000E+01 2.000E+01 3.000E+01 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 0.000E+00 2.400E+01 . . . * . 1.000E-01 2.410E+01 . . . * . 2.000E-01 2.420E+01 . . . * . 3.000E-01 2.430E+01 . . . * . 4.000E-01 2.440E+01 . . . * . 5.000E-01 2.450E+01 . . . * . 6.000E-01 2.460E+01 . . . * . 7.000E-01 2.466E+01 . . . * . 8.000E-01 2.439E+01 . . . * . 9.000E-01 2.383E+01 . . . * . 1.000E+00 2.317E+01 . . . * . 1.100E+00 2.246E+01 . . . * . 1.200E+00 2.174E+01 . . . * . 1.300E+00 2.101E+01 . . .* . 1.400E+00 2.026E+01 . . * . 1.500E+00 1.951E+01 . . *. . 1.600E+00 1.876E+01 . . * . . 1.700E+00 1.800E+01 . . * . . 1.800E+00 1.724E+01 . . * . . 1.900E+00 1.648E+01 . . * . . 2.000E+00 1.572E+01 . . * . . 2.100E+00 1.495E+01 . . * . . 2.200E+00 1.418E+01 . . * . . 2.300E+00 1.342E+01 . . * . . 2.400E+00 1.265E+01 . . * . . 2.500E+00 1.188E+01 . . * . . 2.600E+00 1.110E+01 . . * . . 2.700E+00 1.033E+01 . * . . 2.800E+00 9.560E+00 . *. . . 2.900E+00 8.787E+00 . * . . . 3.000E+00 8.014E+00 . * . . . 3.100E+00 7.240E+00 . * . . . 3.200E+00 6.465E+00 . * . . . 3.300E+00 5.691E+00 . * . . . 3.400E+00 4.915E+00 . * . . . 3.500E+00 4.140E+00 . * . . . 3.600E+00 3.364E+00 . * . . . 3.700E+00 2.588E+00 . * . . . 3.800E+00 1.811E+00 . * . . . 3.900E+00 1.034E+00 .* . . . 4.000E+00 2.587E-01 * . . . 4.100E+00 9.744E-02 * . . . 4.200E+00 7.815E-02 * . . . 4.300E+00 6.806E-02 * . . . 4.400E+00 6.141E-02 * . . . 4.500E+00 5.657E-02 * . . . 4.600E+00 5.281E-02 * . . . 4.700E+00 4.981E-02 * . . . 4.800E+00 4.734E-02 * . . . 4.900E+00 4.525E-02 * . . . 5.000E+00 4.346E-02 * . . . - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - `
Example common-source JFET amplifier circuit with self-bias
Netlist:
`common source jfet amplifier vin 1 0 sin(0 1 60 0 0) vdd 3 0 dc 20 rdrain 3 2 10k rsource 4 0 1k j1 2 1 4 mod1 .model mod1 njf .tran 1m 30m .plot tran v(2,0) v(1,0) .end `
Output:
`legend: *: v(2) +: v(1) time v(2) (*)--------- 1.400E+01 1.600E+01 1.800E+01 2.000E+01 2.200E+01 (+)--------- -1.000E+00 -5.000E-01 0.000E+00 5.000E-01 1.000E+00 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 0.000E+00 1.708E+01 . . * + . . 1.000E-03 1.609E+01 . .* . + . . 2.000E-03 1.516E+01 . * . . . + . 3.000E-03 1.448E+01 . * . . . + . 4.000E-03 1.419E+01 .* . . . + 5.000E-03 1.432E+01 . * . . . +. 6.000E-03 1.490E+01 . * . . . + . 7.000E-03 1.577E+01 . * . . +. . 8.000E-03 1.676E+01 . . * . + . . 9.000E-03 1.768E+01 . . + *. . . 1.000E-02 1.841E+01 . + . . * . . 1.100E-02 1.890E+01 . + . . * . . 1.200E-02 1.912E+01 .+ . . * . . 1.300E-02 1.912E+01 .+ . . * . . 1.400E-02 1.890E+01 . + . . * . . 1.500E-02 1.842E+01 . + . . * . . 1.600E-02 1.768E+01 . . + *. . . 1.700E-02 1.676E+01 . . * . + . . 1.800E-02 1.577E+01 . * . . +. . 1.900E-02 1.491E+01 . * . . . + . 2.000E-02 1.432E+01 . * . . . +. 2.100E-02 1.419E+01 .* . . . + 2.200E-02 1.449E+01 . * . . . + . 2.300E-02 1.516E+01 . * . . . + . 2.400E-02 1.609E+01 . .* . + . . 2.500E-02 1.708E+01 . . * + . . 2.600E-02 1.796E+01 . . + * . . 2.700E-02 1.861E+01 . + . . * . . 2.800E-02 1.900E+01 . + . . * . . 2.900E-02 1.916E+01 + . . * . . 3.000E-02 1.908E+01 .+ . . * . . - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - `
Example inverting op-amp circuit
To simulate an ideal operational amplifier in SPICE, we use a voltage-dependent voltage source as a differential amplifier with extremely high gain. The “e” card sets up the dependent voltage source with four nodes, 3 and 0 for voltage output, and 1 and 0 for voltage input. No power supply is needed for the dependent voltage source, unlike a real operational amplifier. The voltage gain is set at 999,000 in this case. The input voltage source (V1) sweeps from 0 to 3.5 volts in 0.05 volt steps.
Netlist:
`Inverting opamp v1 2 0 dc e 3 0 0 1 999k r1 3 1 3.29k r2 1 2 1.18k .dc v1 0 3.5 0.05 .print dc v(3,0) .end `
Output:
`v1 v(3) 0.000E+00 0.000E+00 5.000E-02 -1.394E-01 1.000E-01 -2.788E-01 1.500E-01 -4.182E-01 2.000E-01 -5.576E-01 2.500E-01 -6.970E-01 3.000E-01 -8.364E-01 3.500E-01 -9.758E-01 4.000E-01 -1.115E+00 4.500E-01 -1.255E+00 5.000E-01 -1.394E+00 5.500E-01 -1.533E+00 6.000E-01 -1.673E+00 6.500E-01 -1.812E+00 7.000E-01 -1.952E+00 7.500E-01 -2.091E+00 8.000E-01 -2.231E+00 8.500E-01 -2.370E+00 9.000E-01 -2.509E+00 9.500E-01 -2.649E+00 1.000E+00 -2.788E+00 1.050E+00 -2.928E+00 1.100E+00 -3.067E+00 1.150E+00 -3.206E+00 1.200E+00 -3.346E+00 1.250E+00 -3.485E+00 1.300E+00 -3.625E+00 1.350E+00 -3.764E+00 1.400E+00 -3.903E+00 1.450E+00 -4.043E+00 1.500E+00 -4.182E+00 1.550E+00 -4.322E+00 1.600E+00 -4.461E+00 1.650E+00 -4.600E+00 1.700E+00 -4.740E+00 1.750E+00 -4.879E+00 1.800E+00 -5.019E+00 1.850E+00 -5.158E+00 1.900E+00 -5.297E+00 1.950E+00 -5.437E+00 2.000E+00 -5.576E+00 2.050E+00 -5.716E+00 2.100E+00 -5.855E+00 2.150E+00 -5.994E+00 2.200E+00 -6.134E+00 2.250E+00 -6.273E+00 2.300E+00 -6.413E+00 2.350E+00 -6.552E+00 2.400E+00 -6.692E+00 2.450E+00 -6.831E+00 2.500E+00 -6.970E+00 2.550E+00 -7.110E+00 2.600E+00 -7.249E+00 2.650E+00 -7.389E+00 2.700E+00 -7.528E+00 2.750E+00 -7.667E+00 2.800E+00 -7.807E+00 2.850E+00 -7.946E+00 2.900E+00 -8.086E+00 2.950E+00 -8.225E+00 3.000E+00 -8.364E+00 3.050E+00 -8.504E+00 3.100E+00 -8.643E+00 3.150E+00 -8.783E+00 3.200E+00 -8.922E+00 3.250E+00 -9.061E+00 3.300E+00 -9.201E+00 3.350E+00 -9.340E+00 3.400E+00 -9.480E+00 3.450E+00 -9.619E+00 3.500E+00 -9.758E+00 `
Example noninverting op-amp circuit
Another example of a SPICE quirk: since the dependent voltage source “e” isn’t considered a load to voltage source V1, SPICE interprets V1 to be open-circuited and will refuse to analyze it. The fix is to connect Rbogus in parallel with V1 to act as a DC load. Being directly connected across V1, the resistance of Rbogus is not crucial to the operation of the circuit, so 10 kΩ will work fine. I decided not to sweep the V1input voltage at all in this circuit for the sake of keeping the netlist and output listing simple.
Netlist:
`noninverting opamp v1 2 0 dc 5 rbogus 2 0 10k e 3 0 2 1 999k r1 3 1 20k r2 1 0 10k .end `
Output:
`node voltage node voltage node voltage ( 1) 5.0000 ( 2) 5.0000 ( 3) 15.0000 `
Example instrumentation amplifier circuit
Note the very high-resistance Rbogus1 and Rbogus2 resistors in the netlist (not shown in schematic for brevity) across each input voltage source, to keep SPICE from thinking V1 and V2 were open-circuited, just like the other op-amp circuit examples.
Netlist:
`Instrumentation amplifier v1 1 0 rbogus1 1 0 9e12 v2 4 0 dc 5 rbogus2 4 0 9e12 e1 3 0 1 2 999k e2 6 0 4 5 999k e3 9 0 8 7 999k rload 9 0 10k r1 2 3 10k rgain 2 5 10k r2 5 6 10k r3 3 7 10k r4 7 9 10k r5 6 8 10k r6 8 0 10k .dc v1 0 10 1 .print dc v(9) v(3,6) .end `
Output:
`v1 v(9) v(3,6) 0.000E+00 1.500E+01 -1.500E+01 1.000E+00 1.200E+01 -1.200E+01 2.000E+00 9.000E+00 -9.000E+00 3.000E+00 6.000E+00 -6.000E+00 4.000E+00 3.000E+00 -3.000E+00 5.000E+00 9.955E-11 -9.956E-11 6.000E+00 -3.000E+00 3.000E+00 7.000E+00 -6.000E+00 6.000E+00 8.000E+00 -9.000E+00 9.000E+00 9.000E+00 -1.200E+01 1.200E+01 1.000E+01 -1.500E+01 1.500E+01 `
Example op-amp integrator circuit with sinewave input
Netlist:
`Integrator with sinewave input vin 1 0 sin (0 15 60 0 0) r1 1 2 10k c1 2 3 150u ic=0 e 3 0 0 2 999k .tran 1m 30m uic .plot tran v(1,0) v(3,0) .end `
Output:
`legend: *: v(1) +: v(3) time v(1) (*)-------- -2.000E+01 -1.000E+01 0.000E+00 1.000E+01 (+)-------- -6.000E-02 -4.000E-02 -2.000E-02 0.000E+00 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 0.000E+00 6.536E-08 . . * + . 1.000E-03 5.516E+00 . . . * +. . 2.000E-03 1.021E+01 . . . + * . 3.000E-03 1.350E+01 . . . + . * . 4.000E-03 1.495E+01 . . + . . *. 5.000E-03 1.418E+01 . . + . . * . 6.000E-03 1.150E+01 . + . . . * . 7.000E-03 7.214E+00 . + . . * . . 8.000E-03 1.867E+00 .+ . . * . . 9.000E-03 -3.709E+00 . + . * . . . 1.000E-02 -8.805E+00 . + . * . . . 1.100E-02 -1.259E+01 . * + . . . 1.200E-02 -1.466E+01 . * . + . . . 1.300E-02 -1.471E+01 . * . +. . . 1.400E-02 -1.259E+01 . * . . + . . 1.500E-02 -8.774E+00 . . * . + . . 1.600E-02 -3.723E+00 . . * . +. . 1.700E-02 1.870E+00 . . . * + . 1.800E-02 7.188E+00 . . . * + . . 1.900E-02 1.154E+01 . . . + . * . 2.000E-02 1.418E+01 . . .+ . * . 2.100E-02 1.490E+01 . . + . . *. 2.200E-02 1.355E+01 . . + . . * . 2.300E-02 1.020E+01 . + . . * . 2.400E-02 5.496E+00 . + . . * . . 2.500E-02 -1.486E-03 .+ . * . . 2.600E-02 -5.489E+00 . + . * . . . 2.700E-02 -1.021E+01 . + * . . . 2.800E-02 -1.355E+01 . * . + . . . 2.900E-02 -1.488E+01 . * . + . . . 3.000E-02 -1.427E+01 . * . .+ . . - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - `
Example op-amp integrator circuit with squarewave input
Netlist:
`Integrator with squarewave input vin 1 0 pulse (-1 1 0 0 0 10m 20m) r1 1 2 1k c1 2 3 150u ic=0 e 3 0 0 2 999k .tran 1m 50m uic .plot tran v(1,0) v(3,0) .end `
Output:
<(1) +: v(3) time v(1) (*)————-1.000E+00 -5.000E-01 0.000E+00 5.000E-01 1.000E+00 (+)————-1.000E-01 -5.000E-02 0.000E+00 5.000E-02 1.000E-01 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 0.000E+00 -1.000E+00 * . + . . 1.000E-03 1.000E+00 . . + . * 2.000E-03 1.000E+00 . . + . . * 3.000E-03 1.000E+00 . . + . . * 4.000E-03 1.000E+00 . . + . . * 5.000E-03 1.000E+00 . . + . . * 6.000E-03 1.000E+00 . . + . . * 7.000E-03 1.000E+00 . . + . . * 8.000E-03 1.000E+00 . .+ . . * 9.000E-03 1.000E+00 . +. . . * 1.000E-02 1.000E+00 . + . . . * 1.100E-02 1.000E+00 . + . . . * 1.200E-02 -1.000E+00 * + . . . . 1.300E-02 -1.000E+00 * + . . . . 1.400E-02 -1.000E+00 * +. . . . 1.500E-02 -1.000E+00 * .+ . . . 1.600E-02 -1.000E+00 * . + . . . 1.700E-02 -1.000E+00 * . + . . . 1.800E-02 -1.000E+00 * . + . . . 1.900E-02 -1.000E+00 * . + . . . 2.000E-02 -1.000E+00 * . + . . . 2.100E-02 1.000E+00 . . + . . * 2.200E-02 1.000E+00 . . + . . * 2.300E-02 1.000E+00 . . + . . * 2.400E-02 1.000E+00 . . + . . * 2.500E-02 1.000E+00 . . + . . * 2.600E-02 1.000E+00 . .+ . . * 2.700E-02 1.000E+00 . +. . . * 2.800E-02 1.000E+00 . + . . . * 2.900E-02 1.000E+00 . + . . . * 3.000E-02 1.000E+00 . + . . . * 3.100E-02 1.000E+00 . + . . . * 3.200E-02 -1.000E+00 * + . . . . 3.300E-02 -1.000E+00 * + . . . . 3.400E-02 -1.000E+00 * + . . . . 3.500E-02 -1.000E+00 * + . . . . 3.600E-02 -1.000E+00 * +. . . . 3.700E-02 -1.000E+00 * .+ . . . 3.800E-02 -1.000E+00 * . + . . . 3.900E-02 -1.000E+00 * . + . . . 4.000E-02 -1.000E+00 * . + . . . 4.100E-02 1.000E+00 . . + . . * 4.200E-02 1.000E+00 . . + . . * 4.300E-02 1.000E+00 . . + . . * 4.400E-02 1.000E+00 . .+ . . * 4.500E-02 1.000E+00 . +. . . * 4.600E-02 1.000E+00 . + . . . * 4.700E-02 1.000E+00 . + . . . * 4.800E-02 1.000E+00 . + . . . * 4.900E-02 1.000E+00 . + . . . * 5.000E-02 1.000E+00 + . . . * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - | textbooks/workforce/Electronics_Technology/Book%3A_Electric_Circuits_V_-_References_(Kuphaldt)/07%3A_Using_The_spice_Circuit_Simulation_Program/7.08%3A_Example_Circuits_and_Netlists.txt |
• Has the system ever worked before? If yes, has anything happened to it since then that could cause the problem?
• Has this system proven itself to be prone to certain types of failure?
• How urgent is the need for repair?
• What are the safety concerns, before I start troubleshooting?
• What are the process quality concerns, before I start troubleshooting (what can I do without causing interruptions in production)?
These preliminary questions are not trivial. Indeed, they are essential to expedient and safe troubleshooting. They are especially important when the system to be trouble-shot is large, dangerous, and/or expensive.
Sometimes the troubleshooter will be required to work on a system that is still in full operation (perhaps the ultimate example of this is a doctor diagnosing a live patient). Once the cause or causes are determined to a high degree of certainty, there is the step of corrective action. Correcting a system fault without significantly interrupting the operation of the system can be very challenging, and it deserves thorough planning.
When there is high risk involved in taking corrective action, such as is the case with performing surgery on a patient or making repairs to an operating process in a chemical plant, it is essential for the worker(s) to plan ahead for possible trouble. One question to ask before proceeding with repairs is, “how and at what point(s) can I abort the repairs if something goes wrong?” In risky situations, it is vital to have planned “escape routes” in your corrective action, just in case things do not go as planned. A surgeon operating on a patient knows if there are any “points of no return” in such a procedure, and stops to re-check the patient before proceeding past those points. He or she also knows how to “back out” of a surgical procedure at those points if needed.
8.02: General Troubleshooting Tips
When first approaching a failed or otherwise misbehaving system, the new troubleshooter often doesn’t know where to begin. The following strategies are not exhaustive by any means, but provide the troubleshooter with a simple checklist of questions to ask in order to start isolating the problem.
As for tips, these troubleshooting suggestions are not comprehensive procedures: they serve as starting points only for the troubleshooting process. An essential part of expedient troubleshooting is probability assessment, and these tips help the troubleshooter determine which possible points of failure are more or less likely than others. Final isolation of the system failure is usually determined through more specific techniques (outlined in the next section—Specific Troubleshooting Techniques).
Prior occurrence
If this device or process has been historically known to fail in a certain particular way, and the conditions leading to this common failure have not changed, check for this “way” first. A corollary to this troubleshooting tip is the directive to keep detailed records of failure. Ideally, a computer-based failure log is optimal, so that failures may be referenced by and correlated to a number of factors such as time, date, and environmental conditions.
Example: The car’s engine is overheating. The last two times this happened, the cause was low coolant level in the radiator.
What to do: Check the coolant level first. Of course, past history by no means guarantees the present symptoms are caused by the same problem, but since this is more likely, it makes sense to check this first.
If, however, the cause of routine failure in a system has been corrected (i.e. the leak causing low coolant level in the past has been repaired), then this may not be a probable cause of trouble this time.
Recent alterations
If a system has been having problems immediately after some kind of maintenance or other change, the problems might be linked to those changes.
Example: The mechanic recently tuned my car’s engine, and now I hear a rattling noise that I didn’t hear before I took the car in for repair.
What to do: Check for something that may have been left loose by the mechanic after his or her tune-up work.
Function vs. non-function
If a system isn’t producing the desired end result, look for what it is doing correctly; in other words, identify where the problem is not, and focus your efforts elsewhere. Whatever components or subsystems necessary for the properly working parts to function are probably okay. The degree of fault can often tell you what part of it is to blame.
Example: The radio works fine on the AM band, but not on the FM band.
What to do: Eliminate from the list of possible causes, anything in the radio necessary for the AM band’s function. Whatever the source of the problem is, it is specific to the FM band and not to the AM band. This eliminates the audio amplifier, speakers, fuse, power supply, and almost all external wiring. Being able to eliminate sections of the system as possible failures reduces the scope of the problem and makes the rest of the troubleshooting procedure more efficient.
Hypothesize
Based on your knowledge of how a system works, think of various kinds of failures that would cause this problem (or these phenomena) to occur, and check for those failures (starting with the most likely based on circumstances, history, or knowledge of component weaknesses).
Example: The car’s engine is overheating.
What to do: Consider possible causes for overheating, based on what you know of engine operation. Either the engine is generating too much heat, or not getting rid of the heat well enough (most likely the latter). Brainstorm some possible causes: a loose fan belt, clogged radiator, bad water pump, low coolant level, etc. Investigate each one of those possibilities before investigating alternatives. | textbooks/workforce/Electronics_Technology/Book%3A_Electric_Circuits_V_-_References_(Kuphaldt)/08%3A_Troubleshooting_--_Theory_And_Practice/8.01%3A_Questions_to_Ask_Before_Proceeding.txt |
After applying some of the general troubleshooting tips to narrow the scope of a problem’s location, there are techniques useful in further isolating it. Here are a few:
Swap identical components
In a system with identical or parallel subsystems, swap components between those subsystems and see whether or not the problem moves with the swapped component. If it does, you’ve just swapped the faulty component; if it doesn’t, keep searching!
This is a powerful troubleshooting method, because it gives you both a positive and a negative indication of the swapped component’s fault: when the bad part is exchanged between identical systems, the formerly broken subsystem will start working again and the formerly good subsystem will fail.
I was once able to troubleshoot an elusive problem with an automotive engine ignition system using this method: I happened to have a friend with an automobile sharing the exact same model of ignition system. We swapped parts between the engines (distributor, spark plug wires, ignition coil—one at a time) until the problem moved to the other vehicle. The problem happened to be a “weak” ignition coil, and it only manifested itself under heavy load (a condition that could not be simulated in my garage). Normally, this type of problem could only be pinpointed using an ignition system analyzer (or oscilloscope) and a dynamometer to simulate loaded driving conditions. This technique, however, confirmed the source of the problem with 100% accuracy, using no diagnostic equipment whatsoever.
Occasionally you may swap a component and find that the problem still exists, but has changed in some way. This tells you that the components you just swapped are somehow different (different calibration, different function), and nothing more. However, don’t dismiss this information just because it doesn’t lead you straight to the problem—look for other changes in the system as a whole as a result of the swap, and try to figure out what these changes tell you about the source of the problem.
An important caveat to this technique is the possibility of causing further damage. Suppose a component has failed because of another, less conspicuous failure in the system. Swapping the failed component with a good component will cause the good component to fail as well. For example, suppose that a circuit develops a short, which “blows” the protective fuse for that circuit. The blown fuse is not evident by inspection, and you don’t have a meter to electrically test the fuse, so you decide to swap the suspect fuse with one of the same rating from a working circuit. As a result of this, the good fuse that you move to the shorted circuit blows as well, leaving you with two blown fuses and two non-working circuits. At least you know for certain that the original fuse was blown, because the circuit it was moved to stopped working after the swap, but this knowledge was gained only through the loss of a good fuse and the additional “down time” of the second circuit.
Another example to illustrate this caveat is the ignition system problem previously mentioned. Suppose that the “weak” ignition coil had caused the engine to backfire, damaging the muffler. If swapping ignition system components with another vehicle causes the problem to move to the other vehicle, damage may be done to the other vehicle’s muffler as well. As a general rule, the technique of swapping identical components should be used only when there is minimal chance of causing additional damage. It is an excellent technique for isolating non-destructive problems.
Example 1: You’re working on a CNC machine tool with X, Y, and Z-axis drives. The Y axis is not working, but the X and Z axes are working. All three axes share identical components (feedback encoders, servo motor drives, servo motors).
What to do: Exchange these identical components, one at a time, Y axis and either one of the working axes (X or Z), and see after each swap whether or not the problem has moved with the swap.
Example 2: A stereo system produces no sound on the left speaker, but the right speaker works just fine.
What to do: Try swapping respective components between the two channels and see if the problem changes sides, from left to right. When it does, you’ve found the defective component. For instance, you could swap the speakers between channels: if the problem moves to the other side (i.e. the same speaker that was dead before is still dead, now that its connected to the right channel cable) then you know that speaker is bad. If the problem stays on the same side (i.e. the speaker formerly silent is now producing sound after having been moved to the other side of the room and connected to the other cable), then you know the speakers are fine, and the problem must lie somewhere else (perhaps in the cable connecting the silent speaker to the amplifier, or in the amplifier itself).
If the speakers have been verified as good, then you could check the cables using the same method. Swap the cables so that each one now connects to the other channel of the amplifier and to the other speaker. Again, if the problem changes sides (i.e. now the right speaker is now “dead” and the left speaker now produces sound), then the cable now connected to the right speaker must be defective. If neither swap (the speakers nor the cables) causes the problem to change sides from left to right, then the problem must lie within the amplifier (i.e. the left channel output must be “dead”).
Remove parallel components
If a system is composed of several parallel or redundant components which can be removed without crippling the whole system, start removing these components (one at a time) and see if things start to work again.
Example 1: A “star” topology communications network between several computers has failed. None of the computers are able to communicate with each other.
What to do: Try unplugging the computers, one at a time from the network, and see if the network starts working again after one of them is unplugged. If it does, then that last unplugged computer may be the one at fault (it may have been “jamming” the network by constantly outputting data or noise).
Example 2: A household fuse keeps blowing (or the breaker keeps tripping open) after a short amount of time.
What to do: Unplug appliances from that circuit until the fuse or breaker quits interrupting the circuit. If you can eliminate the problem by unplugging a single appliance, then that appliance might be defective. If you find that unplugging almost any appliance solves the problem, then the circuit may simply be overloaded by too many appliances, neither of them defective.
Divide system into sections and test those sections
In a system with multiple sections or stages, carefully measure the variables going in and out of each stage until you find a stage where things don’t look right.
Example 1: A radio is not working (producing no sound at the speaker))
What to do: Divide the circuitry into stages: tuning stage, mixing stages, amplifier stage, all the way through to the speaker(s). Measure signals at test points between these stages and tell whether or not a stage is working properly.
Example 2: An analog summer circuit is not functioning properly.
What to do: I would test the passive averager network (the three resistors at the lower-left corner of the schematic) to see that the proper (averaged) voltage was seen at the noninverting input of the op-amp. I would then measure the voltage at the inverting input to see if it was the same as at the noninverting input (or, alternatively, measure the voltage difference between the two inputs of the op-amp, as it should be zero). Continue testing sections of the circuit (or just test points within the circuit) to see if you measure the expected voltages and currents.
Simplify and rebuild
Closely related to the strategy of dividing a system into sections, this is actually a design and fabrication technique useful for new circuits, machines, or systems. It’s always easier begin the design and construction process in little steps, leading to larger and larger steps, rather than to build the whole thing at once and try to troubleshoot it as a whole.
Suppose that someone were building a custom automobile. He or she would be foolish to bolt all the parts together without checking and testing components and subsystems as they went along, expecting everything to work perfectly after its all assembled. Ideally, the builder would check the proper operation of components along the way through the construction process: start and tune the engine before its connected to the drivetrain, check for wiring problems before all the cover panels are put in place, check the brake system in the driveway before taking it out on the road, etc.
Countless times I’ve witnessed students build a complex experimental circuit and have trouble getting it to work because they didn’t stop to check things along the way: test all resistors before plugging them into place, make sure the power supply is regulating voltage adequately before trying to power anything with it, etc. It is human nature to rush to completion of a project, thinking that such checks are a waste of valuable time. However, more time will be wasted in troubleshooting a malfunctioning circuit than would be spent checking the operation of subsystems throughout the process of construction.
Take the example of the analog summer circuit in the previous section for example: what if it wasn’t working properly? How would you simplify it and test it in stages? Well, you could reconnect the op-amp as a basic comparator and see if its responsive to differential input voltages, and/or connect it as a voltage follower (buffer) and see if it outputs the same analog voltage as what is input. If it doesn’t perform these simple functions, it will never perform its function in the summer circuit! By stripping away the complexity of the summer circuit, paring it down to an (almost) bare op-amp, you can test that component’s functionality and then build from there (add resistor feedback and check for voltage amplification, then add input resistors and check for voltage summing), checking for expected results along the way.
Trap a signal
Set up instrumentation (such as a datalogger, chart recorder, or multimeter set on “record” mode) to monitor a signal over a period of time. This is especially helpful when tracking down intermittent problems, which have a way of showing up the moment you’ve turned your back and walked away.
This may be essential for proving what happens first in a fast-acting system. Many fast systems (especially shutdown “trip” systems) have a “first out” monitoring capability to provide this kind of data.
Example #1: A turbine control system shuts automatically in response to an abnormal condition. By the time a technician arrives at the scene to survey the turbine’s condition, however, everything is in a “down” state and its impossible to tell what signal or condition was responsible for the initial shutdown, as all operating parameters are now “abnormal.”
What to do: One technician I knew used a video camera to record the turbine control panel, so he could see what happened (by indications on the gauges) first in an automatic-shutdown event. Simply by looking at the panel after the fact, there was no way to tell which signal shut the turbine down, but the videotape playback would show what happened in sequence, down to a frame-by-frame time resolution.
Example #2: An alarm system is falsely triggering, and you suspect it may be due to a specific wire connection going bad. Unfortunately, the problem never manifests itself while you’re watching it!
What to do: Many modern digital multimeters are equipped with “record” settings, whereby they can monitor a voltage, current, or resistance over time and note whether that measurement deviates substantially from a regular value. This is an invaluable tool for use in “intermittent” electronic system failures. | textbooks/workforce/Electronics_Technology/Book%3A_Electric_Circuits_V_-_References_(Kuphaldt)/08%3A_Troubleshooting_--_Theory_And_Practice/8.03%3A_Specific_Troubleshooting_Techniques.txt |
The following problems are arranged in order from most likely to least likely, top to bottom. This order has been determined largely from personal experience troubleshooting electrical and electronic problems in automotive, industrial, and home applications. This order also assumes a circuit or system that has been proven to function as designed and has failed after substantial operation time. Problems experienced in newly assembled circuits and systems do not necessarily exhibit the same probabilities of occurrence.
Operator error
A frequent cause of system failure is error on the part of those human beings operating it. This cause of trouble is placed at the top of the list, but of course, the actual likelihood depends largely on the particular individuals responsible for operation. When operator error is the cause of a failure, it is unlikely that it will be admitted prior to investigation. I do not mean to suggest that operators are incompetent and irresponsible—quite the contrary: these people are often your best teachers for learning system function and obtaining a history of failure—but the reality of human error cannot be overlooked. A positive attitude coupled with good interpersonal skills on the part of the troubleshooter goes a long way in troubleshooting when human error is the root cause of failure.
Bad wire connections
As incredible as this may sound to the new student of electronics, a high percentage of electrical and electronic system problems are caused by a very simple source of trouble: poor (i.e. open or shorted) wire connections. This is especially true when the environment is hostile, including such factors as high vibration and/or a corrosive atmosphere. Connection points found in any variety of plug-and-socket connector, terminal strip, or splice are at the greatest risk for failure. The category of “connections” also includes mechanical switch contacts, which can be thought of as a high-cycle connector. Improper wire termination lugs (such as a compression-style connector crimped on the end of a
solid wire—a definite faux pas) can cause high-resistance connections after a period of trouble-free service.
It should be noted that connections in low-voltage systems tend to be far more troublesome than connections in high-voltage systems. The main reason for this is the effect of arcing across a discontinuity (circuit break) in higher-voltage systems tends to blast away insulating layers of dirt and corrosion, and may even weld the two ends together if sustained long enough. Low-voltage systems tend not to generate such vigorous arcing across the gap of a circuit break, and also tend to be more sensitive to additional resistance in the circuit. Mechanical switch contacts used in low-voltage systems benefit from having the recommended minimum wetting current conducted through them to promote a healthy amount of arcing upon opening, even if this level of current is not necessary for the operation of other circuit components.
Although open failures tend to more common than shorted failures, “shorts” still constitute a substantial percentage of wiring failure modes. Many shorts are caused by degradation of wire insulation. This, again, is especially true when the environment is hostile, including such factors as high vibration, high heat, high humidity, or high voltage. It is rare to find a mechanical switch contact that is failed shorted, except in the case of high-current contacts where contact “welding” may occur in over current conditions. Shorts may also be caused by conductive build up across terminal strip sections or the backs of printed circuit boards.
A common case of shorted wiring is the ground fault, where a conductor accidentally makes contact with either earth or chassis ground. This may change the voltage(s) present between other conductors in the circuit and ground, thereby causing bizarre system malfunctions and/or personnel hazard.
Power supply problems
These generally consist of tripped overcurrent protection devices or damage due to overheating. Although power supply circuitry is usually less complex than the circuitry being powered and therefore should figure to be less prone to failure on that basis alone, it generally handles more power than any other portion of the system and therefore must deal with greater voltages and/or currents. Also, because of its relative design simplicity, a system’s power supply may not receive the engineering attention it deserves, most of the engineering focus devoted to more glamorous parts of the system.
Active components
Active components (amplification devices) tend to fail with greater regularity than passive (non-amplifying) devices, due to their greater complexity and tendency to amplify overvoltage/overcurrent conditions. Semiconductor devices are notoriously prone to failure due to electrical transient (voltage/current surge) overloading and thermal (heat) overloading. Electron tube devices are far more resistant to both of these failure modes but are generally more prone to mechanical failures due to their fragile construction.
Passive components
Non-amplifying components are the most rugged of all, their relative simplicity granting them a statistical advantage over active devices. The following list gives an approximate relation of failure probabilities (again, top being the most likely and bottom being the least likely):
• Capacitors (shorted), especially electrolytic capacitors. The paste electrolyte tends to lose moisture with age, leading to failure. Thin dielectric layers may be punctured by overvoltage transients.
• Diodes open (rectifying diodes) or shorted (Zener diodes).
• Inductor and transformer windings open or shorted to conductive core. Failures related to overheating (insulation breakdown) are easily detected by smell.
• Resistors open, almost never shorted. Usually, this is due to overcurrent heating, although it is less frequently caused by overvoltage transient (arc-over) or physical damage (vibration or impact). Resistors may also change resistance value if overheated! | textbooks/workforce/Electronics_Technology/Book%3A_Electric_Circuits_V_-_References_(Kuphaldt)/08%3A_Troubleshooting_--_Theory_And_Practice/8.04%3A_Likely_Failures_in_Proven_Systems.txt |
“All men are liable to error;”
—John Locke
Whereas the last section deals with component failures in systems that have been successfully operating for some time, this section concentrates on the problems plaguing brand-new systems. In this case, failure modes are generally not of the aging kind but are related to mistakes in design and assembly caused by human beings.
Wiring problems
In this case, bad connections are usually due to assembly error, such as connection to the wrong point or poor connector fabrication. Shorted failures are also seen, but usually, involve misconnections (conductors inadvertently attached to grounding points) or wires pinched under box covers.
Another wiring-related problem seen in new systems is that of electrostatic or electromagnetic interference between different circuits by way of close wiring proximity. This kind of problem is easily created by routing sets of wires too close to each other (especially routing signal cables close to power conductors) and tends to be very difficult to identify and locate with test equipment.
Power supply problems
Blown fuses and tripped circuit breakers are likely sources of trouble, especially if the project in question is an addition to an already-functioning system. Loads may be larger than expected, resulting in overloading and subsequent failure of power supplies.
Defective components
In the case of a newly-assembled system, component fault probabilities are not as predictable as in the case of an operating system that fails with age. Any type of component—active or passive—may be found defective or of imprecise value “out of the box” with roughly equal probability, barring any specific sensitivities in shipping (i.e fragile vacuum tubes or electrostatically sensitive semiconductor components). Moreover, these types of failures are not always as easy to identify by sight or smell as an age- or transient-induced failure.
Improper system configuration
Increasingly seen in large systems using microprocessor-based components, “programming” issues can still plague non-microprocessor systems in the form of incorrect time-delay relay settings, limit switch calibrations, and drum switch sequences. Complex components having configuration “jumpers” or switches to control behavior may not be “programmed” properly.
Components may be used in a new system outside of their tolerable ranges. Resistors, for example, with too low of power ratings, of too great of tolerance, may have been installed. Sensors, instruments, and controlling mechanisms may be uncalibrated, or calibrated to the wrong ranges.
Design error
Perhaps the most difficult to pinpoint and the slowest to be recognized (especially by the chief designer) is the problem of design error, where the system fails to function simply because it cannot function as designed. This may be as trivial as the designer specifying the wrong components in a system, or as fundamental as a system not working due to the designer’s improper knowledge of physics.
I once saw a turbine control system installed that used a low-pressure switch on the lubrication oil tubing to shut down the turbine if oil pressure dropped to an insufficient level. The oil pressure for lubrication was supplied by an oil pump turned by the turbine. When installed, the turbine refused to start. Why? Because when it was stopped, the oil pump was not turning, thus there was no oil pressure to lubricate the turbine. The low-oil-pressure switch detected this condition and the control system maintained the turbine in shutdown mode, preventing it from starting. This is a classic example of a design flaw, and it could only be corrected by a change in the system logic.
While most design flaws manifest themselves early in the operational life of the system, some remain hidden until just the right conditions exist to trigger the fault. These types of flaws are the most difficult to uncover, as the troubleshooter usually overlooks the possibility of design error due to the fact that the system is assumed to be “proven.” The example of the turbine lubrication system was a design flaw impossible to ignore on start-up. An example of a “hidden” design flaw might be a faulty emergency coolant system for a machine, designed to remain inactive until certain abnormal conditions are reached—conditions which might never be experienced in the life of the system. | textbooks/workforce/Electronics_Technology/Book%3A_Electric_Circuits_V_-_References_(Kuphaldt)/08%3A_Troubleshooting_--_Theory_And_Practice/8.05%3A_Likely_Failures_in_Unproven_Systems.txt |
Fallacious reasoning and poor interpersonal relations account for more failed or belabored troubleshooting efforts than any other impediments. With this in mind, the aspiring troubleshooter needs to be familiar with a few common troubleshooting mistakes.
Trusting that a brand-new component will always be good. While it is generally true that a new component will be in good condition, it is not always true. It is also possible that a component has been mislabeled and may have the wrong value (usually this mislabeling is a mistake made at the point of distribution or warehousing and not at the manufacturer, but again, not always!).
Not periodically checking your test equipment. This is especially true with battery-powered meters, as weak batteries may give spurious readings. When using meters to safety-check for dangerous voltage, remember to test the meter on a known source of voltage both before and after checking the circuit to be serviced, to make sure the meter is in proper operating condition.
Assuming there is only one failure to account for the problem. Single-failure system problems are ideal for troubleshooting, but sometimes failures come in multiple numbers. In some instances, the failure of one component may lead to a system condition that damages other components. Sometimes a component in marginal condition goes undetected for a long time, then when another component fails the system suffers from problems with both components.
Mistaking coincidence for causality. Just because two events occurred at nearly the same time does not necessarily mean one event caused the other! They may be both consequences of a common cause, or they may be totally unrelated! If possible, try to duplicate the same condition suspected to be the cause and see if the event suspected to be the coincidence happens again. If not, then there is either no causal relationship as assumed. This may mean there is no causal relationship between the two events whatsoever, or that there is a causal relationship, but just not the one you expected.
Self-induced blindness. After a long effort at troubleshooting a difficult problem, you may become tired and begin to overlook crucial clues to the problem. Take a break and let someone else look at it for a while. You will be amazed at what a difference this can make. On the other hand, it is generally a bad idea to solicit help at the start of the troubleshooting process. Effective troubleshooting involves complex, multi-level thinking, which is not easily communicated with others. More often than not, “team troubleshooting” takes more time and causes more frustration than doing it yourself. An exception to this rule is when the knowledge of the troubleshooters is complementary: for example, a technician who knows electronics but not machine operation teamed with an operator who knows machine function but not electronics.
Failing to question the troubleshooting work of others on the same job. This may sound rather cynical and misanthropic, but it is sound scientific practice. Because it is easy to overlook important details, troubleshooting data received from another troubleshooter should be personally verified before proceeding. This is a common situation when troubleshooters “change shifts” and a technician takes over for another technician who is leaving before the job is done. It is important to exchange information, but do not assume the prior technician checked everything they said they did or checked it perfectly. I’ve been hindered in my troubleshooting efforts on many occasions by failing to verify what someone else told me they checked.
Being pressured to “hurry up.” When an important system fails, there will be pressure from other people to fix the problem as quickly as possible. As they say in business, “time is money.” Having been on the receiving end of this pressure many times, I can understand the need for expedience. However, in many cases, there is a higher priority: caution. If the system in question harbors great danger to life and limb, the pressure to “hurry up” may result in injury or death. At the very least, hasty repairs may result in further damage when the system is restarted. Most failures can be recovered or at least temporarily repaired in short time if approached intelligently. Improper “fixes” resulting in haste often lead to damage that cannot be recovered in short time, if ever. If the potential for greater harm is present, the troubleshooter needs to politely address the pressure received from others, and maintain their perspective in the midst of chaos. Interpersonal skills are just as important in this realm as technical ability!
Finger-pointing. It is all too easy to blame a problem on someone else, for reasons of ignorance, pride, laziness, or some other unfortunate facet of human nature. When the responsibility for system maintenance is divided into departments or work crews, troubleshooting efforts are often hindered by blame cast between groups. “It’s a mechanical problem . . . it’s an electrical problem . . . it’s an instrument problem . . .” ad infinitum, ad nauseum, is all too common in the workplace. I have found that a positive attitude does more to quench the fires of the blame than anything else.
On one particular job, I was summoned to fix a problem in a hydraulic system assumed to be related to the electronic metering and controls. My troubleshooting isolated the source of trouble to a faulty control valve, which was the domain of the millwright (mechanical) crew. I knew that the millwright on shift was a contentious person, so I expected trouble if I simply passed the problem on to his department. Instead, I politely explained to him and his supervisor the nature of the problem as well as a brief synopsis of my reasoning, then proceeded to help him replace the faulty valve, even though it wasn’t “my” responsibility to do so. As a result, the problem was fixed very quickly, and I gained the respect of the millwright.
9.01: Wires and Connections
Older electrical schematics showed connecting wires crossing, while non-connecting wires “jumped” over each other with little half-circle marks. Newer electrical schematics show connecting wires joining with a dot, while non-connecting wires cross with no dot. However, some people still use the older convention of connecting wires crossing with no dot, which may create confusion.
For this reason, I opt to use a hybrid convention, with connecting wires unambiguously connected by a dot, and non-connecting wires unambiguously “jumping” over one another with a half-circle mark. While this may be frowned upon by some, it leaves no room for interpretational error: in each case, the intent is clear and unmistakable:
9.08: Switches Process Actuated
It is very important to keep in mind that the “normal” contact status of a process-actuated switch refers to its status when the process is absent and/or inactive, not “normal” in the sense of process conditions as expected during routine operation. For instance, a normally-closed low-flow detection switch installed on a coolant pipe will be maintained in the actuated state (open) when there is regular coolant flow through the pipe. If the coolant flow stops, the flow switch will go to its “normal” (un-actuated) status of closed.
A limit switch is one actuated by contact with a moving machine part. An electronic limit switch senses mechanical motion but does so using light, magnetic fields, or other non-contact means.
10.01: Table (landscape view)
Periodic table of chemical elements.
10.02: Table (portrait view)
Periodic table of chemical elements. | textbooks/workforce/Electronics_Technology/Book%3A_Electric_Circuits_V_-_References_(Kuphaldt)/08%3A_Troubleshooting_--_Theory_And_Practice/8.06%3A_Potential_Pitfalls.txt |
Over the centuries scientists have discovered that electricity is predictable and measurable. Being familiar with the fundamentals of electricity will help you to understand how and why electrical circuits work.
01: Fundamentals of Electricity
Learning Task 1
Explain fundamentals of electricity
Over the centuries scientists have discovered that electricity is predictable and measurable. Being familiar with the fundamentals of electricity will help you to understand how and why electrical circuits work.
Basic principles
Electricity is a form of energy. To understand electricity, it is important that you first understand the structure of matter. Anything that occupies space and has weight is called matter. All liquids, gases, and solids are examples of matter in different forms. Matter is made of smaller units called atoms. Atoms can be grouped together in compounds to form molecules.
Atomic theory
Atoms are the most basic part of matter and differ in atomic structure from each other. The structure of the atom can be described in much the same way as the solar system. Instead of the Sun at the centre, there is a nucleus. This nucleus is made of two basic particles: protons and neutrons.
Neutrons make up the mass (or weight equivalency) of the atom, have no electrical charge, and are considered to be neutral. Protons are particles that have a positive (+) electrical charge and cannot be separated from the nucleus. Surrounding the nucleus in orbits are electrons. These are tiny particles with a negative (–) electrical charge. Figure 1 shows a model of a carbon atom.
1. Carbon atom
2. Hydrogen and copper atoms
3. Electrical attraction
4. Transmission of impulse
Sources of electrical force
You have just learned that if there is a surplus of electrons at one end of a conductor and a deficiency at the other end, a current flows in the conductor. There are devices that create this difference in charge so that a current will flow. These devices are referred to as sources of electromotive force. These sources include:
• chemical
• electromagnetic induction
• friction
• heat
• pressure
• light
Chemical
A battery is a source of electrical force due to the chemical reaction that takes place between plates and an electrolyte. This reaction causes a buildup of positive ions on one plate and negative ions on the other plate. This electrical difference between the plates is also known as potential difference.
Electromagnetic induction
Electric force can be generated by using a magnetic field. This is the method by which most of the electrical energy we use is produced. An example is an alternator or generator.
Friction
Friction can cause free electrons to move from one body to another and be stored there temporarily. When you walk across a carpet, electrons are transferred to the atoms in your body and you return them to other atoms when you touch a metallic object.
Heat
If two unlike metals are placed together and heated, they will produce electrical force. An example is the thermocouple in a furnace.
Pressure
Certain crystals will produce electricity if they are squeezed under extreme pressure. An example is a barbecue starter (also called piezoelectric generator).
Light
Some crystals and semiconductors will produce electrical force when they are exposed to light. An example is the photocell in a calculator.
All six of these sources of EMF achieve the same thing. They separate charge by:
• imparting energy to the electrons
• pushing them against an electrostatic field
• causing a surplus of electrons (negative charge) at one terminal of the source and a deficiency of electrons (positive charge) at the other terminal
In a sense, the process can be likened to compressing a spring. The energy stored in the compressed spring can be used later to do useful work. The same is true of the separated charges: they store energy that can be used to do useful work.
Electrical energy always comes from some other form of energy. The source of EMF is simply the device that makes the conversion from some other form of energy to electrical energy. | textbooks/workforce/Electronics_Technology/Book%3A_Electrical_Fundamentals_Competency_(Industry_Training_Authority_of_BC)/01%3A_Basic_Principles_of_Electricity/01%3A_Fundamentals_of_Electricity/1.01%3A_Basic_principles.txt |
Electrical circuits and units of measurement
The term circuit refers to a circular journey or loop. In the case of an electrical circuit, it is the closed path or loop travelled by the electrons. The movement or flow of electrons (current) is predictable and measurable, depending on a number of variables within the circuit.
Polarity
Electrical polarity (positive and negative) is present in every electrical circuit. Electrons flow from the negative pole to the positive pole. In a direct current (DC) circuit, one pole is always negative, the other pole is always positive, and the electrons flow in one direction only. In an alternating current (AC) circuit, the two poles alternate between negative and positive, and the direction of the electron flow reverses.
Circuit components
A closed circuit provides a complete path for the flow of electrons through conductors. Included in this circuit there must be a resistance (or load), which will do the work and some form of control. For a circuit to be operational it must contain some basic components (Figure 5). These include:
• power source
• conductors
• controls
• load
• protection
Power source
In equipment, the power source is the battery when the engine is off and the generator when the engine is running. In most buildings, it is the power supplied by the local service provider.
Conductors
Conductors are wires or cables wrapped in insulation that carry the current in the circuit. A common ground circuit conductor could be the frame or body of the equipment or the frame on a vehicle.
Controls
Switches are used to turn the current on and off or to regulate the flow of electricity. Switches can be operated mechanically by vacuum, pressure, or electricity.
Load
The load converts electrical energy to work, such as with electric motors, bulbs, heater coils, or horns.
Protection
Fuses, circuit breakers, or fusible links must be used to prevent damage to the source, load, and conductors.
1. Basic circuit
2. Ohm’s law circuit aid
3. Power circuit aid
Try to solve the following questions for power, using Ohm’s law calculations.
1. How many amps will flow through a 96 W headlight bulb in a 12 V system?
The formula is I = P ÷ E.
Therefore I = 96 W ÷ 12 V.
The result is I = 8 A.
This could be an important consideration in selecting the correct circuit protection device. A fuse with a rating of more than 8 A would have to be chosen in this situation.
2. How much power will a soldering gun produce if it uses 6 A in a 120 V electrical system?
The formula is P = E × I.
Therefore P = 120 V × 6 A.
The result is P = 720 W.
Soldering guns are rated in watts. The higher the wattage rating of the gun, the more heat it will produce.
Now complete the Learning Task Self-Test.
1.E: Self-Test 1
Self-Test 1
1. What are the tiny particles that matter is made of called?
1. Compounds
2. Atoms
3. Ions
4. Protons and neutrons
2. What are elements called that have atoms with electrons that are easily freed?
1. Ions
2. Conductors
3. Insulators
4. Elements
3. Which of the following best describes copper?
1. Conductor
2. Insulator
3. Semiconductor
4. Valence electron
4. Why are insulators useful?
1. They transport an electrical charge.
2. They do not transport an electrical charge.
3. They readily release valence electrons.
4. They will ionize easily when subjected to voltage.
5. In what units is current measured?
1. Volts
2. Amperes
3. Ohms
4. EMF
6. A source of electromotive force can be from a chemical reaction.
1. True
2. False
1. In a DC circuit the poles alternate from positive to negative.
1. True
2. False
2. What is the device called that is used to turn a circuit on and off?
1. A control
2. A conductor
3. A load
4. A protector
3. Which of the following best describes an electric motor?
1. A control
2. A load
3. A fuse
4. A conductor
Use Ohm’s law for the following questions.
E = I × R, where:
• Volts (V) is represented by “E” for electromotive force.
• Amperes (A) is represented by “I” for intensity of current.
• Ohms (Ω) is represented by “R” for resistance.
1. If resistance in a circuit is 6 Ω and the pressure is 24 V, what is the current flow?
1. 2 A
2. 4 A
3. 6 A
4. 8 A
2. If a circuit had a current flow of 8 A and the resistance is 20 Ω, what is the pressure in volts?
1. 120 V
2. 160 V
3. 2.5 V
4. 25 V
1. If a circuit has a current flow of 5 A and a pressure of 120 V, what is the resistance?
1. 24 Ω
2. 12 Ω
3. 6 Ω
4. 3 Ω
Use the power formula for the following questions.
watts = volts × amps or P = E × I
1. How much power will a heater produce if it uses 15 A in a 120 V electrical system?
1. 1800 W
2. 1500 W
3. 900 W
4. 1200 W
2. How many amps will flow through a 60 W headlight bulb in a 24 V system?
1. 6 A
2. 2.5 A
3. 25 A
4. 8 A
3. Use Ohm’s law to complete the following chart.
voltage
current
resistance
500 mA
240
12
1000
12
8 A
5
20 000
120
10
0.15 A
80
3
0.0002 A
4. Use the power formula to complete the following chart.
power
voltage
current
1500 W
12.5 A
40 W
12 V
12 V
300 mA
200 W
10 A
96 W
12 V
12 V
40 A | textbooks/workforce/Electronics_Technology/Book%3A_Electrical_Fundamentals_Competency_(Industry_Training_Authority_of_BC)/01%3A_Basic_Principles_of_Electricity/01%3A_Fundamentals_of_Electricity/1.02%3A_Electrical_circuits_and_units_of_me.txt |
Learning Task 2
Describe basic circuit concepts
You must understand how basic circuits function to properly diagnose and repair electrical problems. Now that you understand a simple circuit and how the basic components are connected, you can assemble more complex circuits and observe their characteristics.
Basic electrical circuits
A circuit must provide a complete path for current flow from the power source. The current must flow through a control device into an electrical load and back to the power source through a wire or through a vehicle chassis.
In equipment, wire is normally used only on the insulated side of the circuit, since the return circuit is the chassis. Some components may require a ground wire from the component to the frame This type of circuit is called the single wire system (Figure 1).
1. Single wire circuit
2. Two wire circuit
There are three types of basic electrical circuits:
• series circuits
• parallel circuits
• series-parallel (combination) circuits
2.02: Series Circuits
Series circuits
The electrical term in series refers to a circuit in which two or more components are connected one after another in order that the current can only flow through one path. The switch that controls the circuit is always in series with the loads. If more than one switch is used, both must be closed for the circuit to function. Circuit protectors (such as fuses) will also be in series. If any one of the components in a series circuit opens, the circuit will not function (Figure 3).
1. Series circuit
2. Series circuit
Perform the following calculations:
1. Total resistance or RT will equal the sum of the individual resistances.
RT = R1 + R2 + R3
RT = 2 Ω + 4 Ω + 6 Ω
RT = 12 Ω
2. Now apply Ohm’s law and calculate the current flow in the circuit.
I = E ÷ R
I = 12 V ÷ 12 Ω
I = 1 A
3. Current flow is the same throughout the circuit. By using Ohm’s law you can determine how much voltage will be used by each of the loads.
The 2 ohm resistor will require:
E = I × R
E = 1 A × 2 Ω
E = 2 V
The 4 ohm resistor will require:
E = I × R
E = 1 A × 4 Ω
E = 4 V
The 6 ohm resistor will require:
E = I × R
E = 1 A × 6 Ω
E = 6 V
Add the individual voltages together and you will notice that they equal the original source voltage of 12 V.
ET = 2 V + 4 V + 6 V
ET = 12 V
The voltage that is used up in the circuit by the load is called voltage drop. This voltage drop is valuable in diagnosis as a measure of the resistance of a circuit. Some voltage may be lost in a circuit because of poor connections. If the voltage drop in connections (caused by high resistance) becomes too great, the load may not function properly or may not even work.
2.03: Parallel Circuits
The parallel circuit (Figure $1$) has completely different characteristics. In a parallel circuit, two or more loads are connected side by side and are controlled by one or more switches. The different loads can each have their own switch, but the major difference is that each of the loads has access to the same amount of voltage and can operate independently of the others. There is more than one path through which the current can flow.
saf
$\begin{array}{l}{\mathrm{I}_{1}=\frac{\mathrm{E}_{1}}{\mathrm{R}_{1}}=\frac{120}{40}=3 \mathrm{amps}} \ {\mathrm{I}_{2}=\frac{\mathrm{E}_{2}}{\mathrm{R}_{2}}=\frac{120}{10}=12 \mathrm{amps}} \ {\mathrm{I}_{3}=\frac{\mathrm{E}_{3}}{\mathrm{R}_{3}}=\frac{120}{240}=0.5 \mathrm{amp}}\end{array}$
$R_{T}=\frac{E_{T}}{I_{T}}=\frac{120}{15.5}=7.7 \text { ohms }$
$R_{T}=\frac{1}{\frac{1}{R_{1}}+\frac{1}{R_{2}}+\frac{1}{R_{3}} \ldots}$
\begin{aligned} R_{T}=& \frac{1}{\frac{1}{40}+\frac{1}{10}+\frac{1}{240}}=7.7 \text { ohms } \ R_{T}=& \frac{1}{\frac{6}{240}+\frac{24}{240}+\frac{1}{240}} \ R_{T}=& \frac{\frac{240}{240}}{31} \ R_{T}=& 7.7 \text { ohms } \end{aligned}
2.04: Series-parallel Circuits
Series-parallel circuits
The series-parallel circuit combines the two previously described types of circuits into one operating system with some distinct advantages. By introducing a load or resistor in series with a parallel circuit, the current flow through the circuit can be controlled (Figure 9).
1. Series-parallel circuit
Using Ohm’s law you can calculate total current flow.
I = E ÷ R
I = 12 V ÷ 2.3 Ω
I = 5.15 mA
2.05: Polarity and direction of current flow
Polarity and direction of current flow
Earlier you learned about the term polarity, referring to the charge at one point with respect to another. When working with electrical circuits, we often refer to the polarity between different points in the circuit. Understanding polarity is important for connecting the leads of polarity-dependent devices such as some meters and motors. Polarity is also important for determining the direction of current flow. In Figure 10 the current leaves the source at the negative terminal, travels around the circuit in a clockwise direction, and re-enters the source at the positive terminal.
1. Polarity
It is important to notice that current flows through loads from negative to positive, and current flows through sources from positive to negative. A more precise way of stating this is that outside the source, current flows from negative to positive, but inside the source current flows from positive to negative.
Now complete the Learning Task Self-Test.
2.E: Self-Test 2
Self-Test 2
1. What takes the place of a ground return wire in a single wire system?
1. Fuse
2. Case ground
3. Circuit breaker
4. Chassis
2. How many paths does a series circuit have for current flow?
1. 1
2. 2
3. 3
4. 4
3. What is a circuit called that has more than one path for current flow?
1. Series circuit
2. Complex circuit
3. Compound circuit
4. Parallel circuit
4. What must the total voltage drop in a circuit be equal to?
1. The source voltage
2. The first voltage drop
3. Half the source voltage
4. Twice the source voltage
5. A 12 V circuit with a 4 ohm resistor will have a current of 6 A.
1. True
2. False
6. A 120 V circuit with a current of 10 A will have a load with what resistance?
1. 12 Ω
2. 24 Ω
3. 6 Ω
4. 10 Ω
1. If one load fails in a parallel circuit, all other loads will fail.
1. True
2. False
2. What is the total resistance in a series circuit with four resistors rated at 2 Ω each?
1. 2 Ω
2. 4 Ω
3. 6 Ω
4. 8 Ω
3. A 120 V parallel circuit has three resistors: 20 Ω, 12 Ω, and 24 Ω. What is the current?
1. 6 A
2. 18 A
3. 21 A
4. 24 A
4. What is the total resistance for a 120 V circuit with three resistors of 20 Ω, 12 Ω, and 24 Ω in parallel?
1. 6 Ω
2. 8 Ω
3. 12 Ω
4. 24 Ω | textbooks/workforce/Electronics_Technology/Book%3A_Electrical_Fundamentals_Competency_(Industry_Training_Authority_of_BC)/01%3A_Basic_Principles_of_Electricity/02%3A_Basic_Circuit_Concepts/2.01%3A_Basic_Electrical_Circuits.txt |
A magnet attracts ferrous metals and some alloys. Magnets can take three forms:
• natural
• artificial
• electric
Natural magnets (i.e., magnetite) are very weak. Artificial magnets are made from magnetic materials (such as iron, nickel, and cobalt) and are given a strong magnetic force during construction. These are permanent magnets and have some limited use. Electromagnets can be easily turned on and off and are in common use because they are not permanent. They are called temporary magnets.
03: Electromagnetism
If a magnet is suspended in the air, it will always turn and align with Earth's north and south poles. The two ends, called the magnetic poles, are where the force is strongest.
A magnetic field of force is set up between the two poles. You can think of it as invisible lines of force traveling from one pole to the other. The magnetic lines (flux lines) are continuous and always form loops. These invisible lines can be seen if you sprinkle iron filings on a piece of paper placed over a bar magnet (Figure \(1\)).
Characteristics of magnetic lines of force
Magnets have some specific rules governing their operation.
Magnetic lines of force possess direction
These lines are continuous and extend from the north pole to the south pole of the magnet (Figure \(2\)).
Magnetic lines of force always form complete loops
The lines do not begin and end at the poles but rather pass through the magnet to form complete loops. If you were to cut a magnet in half, you could observe the magnetic field between the two pieces of the magnet (Figure \(3\)).
Magnetic lines of force always form tight loops
This rule explains the idea of attraction. The flux lines attempt to pull in as close to the magnet as possible, just like rubber bands. They also try to concentrate at each pole. If you place two unlike poles together, they try to become one big magnet and shorten the lines of force (Figure \(4\)).
Magnetic lines of force repel each other
If magnetic lines of force act like rubber bands, why don’t they collapse into the center? The reason is that they repel each other. Look back at Figure 3; notice that the lines tend to diverge as they move away from the poles, rather than converge or even remain parallel. This results from their mutual repulsion.
Magnetic lines of force never cross, but must always form individual loops
The mutual repulsion of each magnetic line accounts for this effect. This explains why like poles repel each other. If the lines cannot cross each other, then they must exert a force against each other. If you could see the lines of force, they would look like the diagram in (Figure \(5\)).
Magnetic lines of force can pass more easily through material that can be magnetized
The magnetic lines of force will distort to include a piece of iron in the field. This will have the effect of turning the iron into a temporary magnet. Then the opposite poles of the two magnets will attract each other and try to shorten the flux lines. This accounts for the attraction of unmagnetized ferromagnetic objects (Figure \(6\)).
There is no insulation against magnetic lines of force
All magnetic field lines must terminate on the opposite pole, which means there is no way to stop them. Nature must find a way to return the magnetic field lines back to an opposite pole. However, magnetic fields can be rerouted around objects. This is a form of magnetic shielding. By surrounding an object with a material that can “conduct” magnetic flux better than the materials around it, the magnetic field will tend to flow along this material and avoid the objects inside. This allows the field lines to terminate on the opposite poles, but just gives them a different route to follow (Figure \(7\)).
Alignment of the atoms
If you took a permanent magnet and cut it in half, you would have two permanent magnets, each with a north and south pole. If you continued cutting each in half, you would have more magnets. This suggests that if you could cut right down to the atom, it would also be a perfect permanent magnet.
This theory can be extended to non-magnetic material as well. Each of the atoms is a magnet, but they are all pointing in different directions. If you can get enough atoms pointing in the same direction, you will have a magnet. All you have to do is expose the piece of metal to flux lines, and the atoms will align.
These atoms tend to form in groups called domains. When the domain becomes large enough, the entire piece of metal becomes the domain and exerts force. When all of the atoms become aligned, the piece has become saturated and cannot get any stronger. | textbooks/workforce/Electronics_Technology/Book%3A_Electrical_Fundamentals_Competency_(Industry_Training_Authority_of_BC)/01%3A_Basic_Principles_of_Electricity/03%3A_Electromagnetism/3.01%3A_Magnetic_Fields.txt |
Electricity and magnetism
There is a direct relationship between electricity and magnetism. If there is current flow in a conductor there will be lines of force created around the conductor. If you could look at the magnetic field formed around a current-carrying conductor, it would look like Figure \(1\).
Note that the lines of force circle the conductor in rings and have direction. The direction of the lines of force depends on the direction of electron flow. If you know the direction of electron flow, you can determine the direction of the lines of force by using your left hand.
The “left-hand rule” says that if you hold the conductor in your left hand with your thumb pointing in the direction of the electron current flow, your fingers will curl in the direction of the lines of force. You will sometimes find this referenced as the “right-hand rule” from those using convention flow notation.
Interaction of fields
Magnetic fields around a current-carrying conductor act in the same way as the fields around a permanent magnet. In Figure \(2\), two conductors have been moved close together. The current is going in opposite directions, as indicated by the symbol in the end of the conductor. An X indicates electron flow in; a dot indicates electron flow out. The magnetic lines of force try to push the two conductors apart because they are in opposite directions. The arrows indicate the direction of the magnetic force.
If one of the conductors has the current reversed, then the magnetic lines of force travel in the same directions. When this occurs the lines of force try to contract and pull tight, just as they did with a permanent magnet. The resulting force will try to pull the two conductors together (Figure \(3\)).
Conductors in loops
If a conductor carrying a current is formed into a loop, the magnetic field will be arranged differently. It will form looped lines of force with a north pole on one side of the loop and a south pole on the other. The magnetic flux lines add to each other and produce a much denser magnetic field in the center of the coil (Figure \(4\)).
Electromagnets
If a piece of soft iron is placed in the coil and a current is passed through the coil in one direction, the magnetic field of the coil causes the domains to align in the iron. This causes poles to form in the iron and creates an electromagnet, as shown in \(5\).
The strength of the electromagnet varies with the number of loops formed, the strength of the electric current, and the type of core in the winding. Because the iron core has a low magnetic retention, the magnetic field collapses when the current stops flowing. The iron core is no longer magnetized and will release whatever it was being used to hold or pull inward.
Electric motors and generators
Electromagnets are probably most commonly used in motors and generators. We have seen that magnetism can be caused by electricity. Electric motors use the force of electromagnets to produce rotation. On the other hand, electricity can be produced by magnetism. When a conductor is moved through a magnetic field or a magnet is moved past a conductor, the movement will induce a voltage in the conductor. Most electricity is generated in this way.
To generate a voltage, three elements must be combined (Figure \(6\):
1. a conductor
2. a magnetic field
3. movement by either the conductor or the magnetic field
The amount of voltage produced will depend on the strength of the magnetic field and the speed at which the conductor or the field moves. A conductor that moves through a magnetic field quickly will generate a higher voltage than one that moves more slowly.
A conductor that moves through a strong magnetic field will generate a higher voltage than one moved through a weak magnetic field.
Alternating current
Electric current that flows in one direction for a split second then changes direction in another split second is called alternating current (AC). In an alternating voltage, the polarity reverses direction periodically. The spinning mechanical motion of an electric generator produces AC voltage and current.
AC waveform and hertz
Hertz is the unit used to describe the frequency of AC direction change. Figure \(7\) is a graphic illustration using a curved line with arrows to indicate a change of direction in AC electron flow. Starting at point A, the current flows in one direction, and then at 120 volts it changes direction, drops to 0 volts, and continues to 120 volts, where it changes direction again back to point B at 0 volts.
If it takes one second to complete the cycle from A to B, we would say the frequency is 1 hertz. Household utility AC current is supplied to the customer at 60 hertz, meaning 60 cycles per second.
Single-phase power supply
Single-phase electric power refers to the distribution of alternating current electric power using a system in which all the voltages of the supply vary in unison. Single-phase distribution is used when loads are mostly lighting and heating, and with a few large electric motors. Single-phase power typically comprises one voltage that is carried between two separate conductors. The two hot lines are called Line 1 and Line 2. In some systems, a grounded neutral, often labeled N, is provided that reduces the referenced voltage in half. These systems are typically found in residential and small commercial applications.
Three-phase AC power supply
Three-phase electrical power refers to a type of electrical power distribution in which three or more energized electrical conductors are carrying alternating currents. Examples of three-phase power systems are industrial applications and power transmission. Three-phase power supplies are used to power large motors and other heavy loads. A three-phase system is generally more economical than equivalent single-phase or two-phase (an uncommon power supply) systems at the same voltage.
Three-phase power comprises three independent voltages that are carried on three separate conductors. The three hot lines are called Line 1, Line 2, and Line 3. Three-phase power is typically found in commercial and industrial buildings.
Now complete the Learning Task Self-Test.
3.E: Self-Test 3
Self-Test 3
1. There are three types of magnets: natural, artificial, and electric.
1. True
2. False
2. Natural magnets have the strongest force.
1. True
2. False
3. If the south poles of two magnets are brought together, what they will do?
1. Conduct
2. Relate
3. Saturate
4. Repel
4. Changing which of the following will also change the strength of an electromagnet?
1. Direction of current flow
2. Size of wires
3. The length of the core
4. Amount of current flow
5. What is the core of an electromagnet usually made from?
1. Air
2. Soft iron
3. Aluminum
4. Copper
6. What two elements must be combined with a conductor to generate a voltage?
1. Magnetic field and a current
2. Current and movement
3. Coil and a magnet
4. Magnetic field and movement
7. Magnetic lines of force never cross.
1. True
2. False
04: Answer Key
Answer Key
Self-Test 1
1. b. Atoms
2. b. Conductors
3. a. Conductor
4. b. They do not transport an electrical charge.
5. b. Amperes
6. a. True
7. b. False
8. a. A control
9. d. A load
10. b. 4 A
11. b. 160 V
12. a. 24 Ω
13. a. 1800 W
14. b. 2.5 A
15. voltage
current
resistance
120
500 mA
240
12
0.012 A
1000
12
8 A
1.5
5
0.00025 A
20 000
120
10
12
12
0.15 A
80
3
0.0002 A
15 000
16. power
voltage
current
1500 W
120 V
12.5 A
40 W
12 V
4 A
3.6 W
12 V
300 mA
200 W
20 V
10 A
96 W
12 V
8 A
480 W
12 V
40 A
Self-Test 2
1. d. Chassis
2. a. 1
3. d. Parallel circuit
4. a. The source voltage
5. b. False
6. a. 12 Ω
7. b. False
8. d. 8 Ω
9. c. 21 A
10. a. 6 Ω
Self-Test 3
1. a. True
2. b. False
3. d. Repel
4. d. Amount of current flow
5. b. Soft iron
6. d. Magnetic field and movement
7. a. True | textbooks/workforce/Electronics_Technology/Book%3A_Electrical_Fundamentals_Competency_(Industry_Training_Authority_of_BC)/01%3A_Basic_Principles_of_Electricity/03%3A_Electromagnetism/3.02%3A_Electricity_and_Magnetism.txt |
All electrical components are rated with different current, voltage, and other values, depending on their use. Replacing an electrical component with one of a different value could present a serious safety hazard to the person using the equipment. Should you have to replace an electrical component at any time, always be sure that the current, voltage, and other electrical ratings of the replacement match those of the original.
In addition, to ensure public safety from electrical and fire hazards, the Canadian Standards Association (CSA) approves electrical components. Each component is tested before it can be sold on the Canadian market. Always use only CSA-approved equipment. The CSA approval should be clearly visible on the component or the package.
You may have to assemble devices in a circuit from plans or drawings in which symbols are used to represent basic electrical devices and components. Although some plans use pictures of the devices instead of symbols, you should be familiar with the symbols so that you can identify each individual device. Not all electrical symbols are standard, but most symbols can be easily recognized.
05: Circuit Components and their Schematic Symbols
Electrical systems
An electrical system has two main conditions: it is closed or it is open. Closed means the circuit is complete and conducting. Open means the circuit is incomplete and no current flows.
There are different electrical systems, identified by voltage. The term low voltage is relative and its definition varies by context. The Canadian Electrical Code defines low voltage as from 31 V to 750 V and systems operating at 30 volts or less.
Automotive systems normally use direct current and are rated up to 24 volts. Residential alternating current voltage may be 120 or 240 volts. Lighting and small appliances normally use 120 volts. Clothes dryers, stoves, and ovens use 240 volts. Shop equipment also uses either 120 or 240 volts. Most hand-held electric tools and many shop tools use 120 volts or battery power. Some equipment, such as electric welders, use 240 volts.
5.1
Light-emitting diodes (LEDs) produce light from electricity using semiconductor materials. They operate from a low DC voltage and produce little heat because there is no incandescent filament. They are available in a range of colours, with red, green, and yellow being the most common.
The seven-segment number display (Figure \(2\)) uses one LED for each section to create different numbers from 0 to 9.
5.E
Self-Test 1
1. Match the device on the left with its purpose on the right.
1. Circuit breaker 1. Protects circuits
2. Relay 2. Electric switch
3. Solenoid 3. Variable control
4. Rheostat 4. Movable core
2. What best describes tapped or stepped resistors?
1. They have two or more fixed values.
2. They have only one unchangeable rating.
3. They have a variable range of resistance.
4. They are used to control charging systems.
3. How is a fuse different from a circuit breaker?
1. A fuse acts like a diode.
2. A circuit breaker doesn’t need a ground.
3. A fuse can be reset and a circuit breaker cannot.
4. A circuit breaker can be reset and a fuse cannot.
4. 6 gauge wire is smaller than 18 gauge.
1. True
2. False
5. What are conductors normally made from?
1. Steel
2. Copper
3. Soft iron
4. Aluminum
6. Receptacles are one-half of a two-piece multi-contact connector.
1. True
2. False
1. What are circuit breakers, fuses, and thermal limiters all examples of?
1. Relays
2. Switches
3. Receptacles
4. Protection devices
2. How many gauges of difference must there be between a fusible link and a conductor?
1. 2
2. 4
3. 6
4. 8
3. Relays require a power circuit and a control circuit.
1. True
2. False
4. What are transformers used for?
1. To act like a relay
2. To increase amperage
3. To increase or decrease voltage
4. To change the current from DC to AC
5. Who is responsible for testing all electrical components?
1. ITA
2. NSA
3. CSA
4. DNA
6. Closed means the circuit is complete and conducting.
1. True
2. False
7. What voltage other than 120 V does a residential system use?
1. 180 V
2. 200 V
3. 240 V
4. 280 V | textbooks/workforce/Electronics_Technology/Book%3A_Electrical_Fundamentals_Competency_(Industry_Training_Authority_of_BC)/02%3A_Unit_II-_Common_Circuit_Components_and_Their_Symbols/05%3A_Circuit_Components_and_their_Schematic_Symbols/5.0.txt |
The ability to read and understand a wiring diagram is important for any tradesperson. You may need to repair a power tool, install a heat pump, or try to find a fuse in a car. Any of these situations requires an ability to read and understand a wiring diagram.
06: Wiring Diagrams
Electrical symbols may be different for each manufacturer, but in most cases they are standard. Every manufacturer’s diagram should have a symbol identification chart or “key” located in the wiring book. Some examples of electrical symbols are shown in Figure \(1\.
6.02: Types of Electrical Diagra
There are four basic types of electrical diagrams:
• schematic
• wiring
• block
• pictorial
Schematic Diagrams
The schematic diagram (Figure \(1\)), often called a ladder diagram, is intended to be the simplest form of an electrical circuit. This diagram shows the circuit components on horizontal lines without regard to their physical location. It is used for troubleshooting because it is easy to understand the operation of the circuit. The loads are located on the far right of the diagram, and the controls for each load are located to the left. To understand the sequence of operation, the drawing is read from the upper left corner and then from left to right, and from top to bottom.
Wiring diagrams
The wiring diagram (Figure \(2\)) shows the relative layout of the circuit components using the appropriate symbols and the wire connections. Although a wiring diagram is the easiest to use for wiring an installation, it is sometimes difficult to understand circuit operation and is not as applicable for troubleshooting.
Block diagrams
The block diagram (Figure \(3\)), also called a functional block diagram, is used to describe the sequence of circuit operations. This diagram indicates by functional descriptions, showing which components must operate first in order to get a final outcome. They do not refer to specifics like device symbols or related wire connections.
Pictorial diagrams
A pictorial diagram (Figure \(4\)) shows the circuit components in more detail, as they really look, and indicates how the wiring is attached. These diagrams can be used to locate components in a complex system.
Now complete the Learning Task Self-Test.
6.E: Self Test 2
Self-Test 2
1. A schematic diagram is often called a ladder diagram.
1. True
2. False
2. What is the fourth type of wiring diagram, in addition to schematic, wiring, and block diagrams?
1. Line
2. Oblique
3. Pictorial
4. Isometric
3. A schematic diagram shows all physical locations of components.
1. True
2. False
4. For which operations is a wiring diagram best suited?
1. Diagnosing
2. Sequencing
3. Installation
4. Troubleshooting
5. A pictorial diagram is used to locate components in complex systems.
1. True
2. False
6. A block diagram includes symbols.
1. True
2. False
7.01: Series Circ
Electrical components can be connected in different configurations to form circuits for different power outputs and applications.
• 7.1: Series Circuits
A series circuit is constructed by connecting all of the circuit components in line with one another.
• 7.2: Parallel Circuits
The parallel circuit is probably the most common type of circuit you will encounter. Loads in power distribution systems are usually connected in parallel with each other in one way or another. A parallel circuit is constructed by connecting the terminals of all the individual load devices so that the same value of voltage appears across each component.
• 7.3: Voltage Source Circuits
Multiple power sources can be connected in series or parallel in order to meet the different voltage or current output requirements for various applications: (1) Power sources are connected in series to increase the voltage output and (2) Power sources are connected in parallel to increase the current capacity
• 7.4: Three-wire Power Supply System
• 7.E: Self-Test 3
07: Common Circuit Characteristics
A series circuit is constructed by connecting all of the circuit components in line with one another. The schematic diagram in Figure \(1\) is an example of a simple series circuit. In this case, a battery (source) is connected through a switch to three resistors (load devices), all of which are in line with one another.
When the switch is closed, there is only one path for current flow. Any circuit that provides only one path for current flow is categorized as a series circuit.
If any part of a series circuit is opened, the current cannot flow and none of the components will operate. The circuit may be opened by the switch or by the failure of a component in the circuit. For example, some decorative lights have clusters within the string that are connected as a series circuit. If one lamp burns out (or opens), all the other lamps go out. You then have to test each lamp individually to find the failed bulb, and this gets very challenging if two bulbs happen to be damaged.
Application of series circuits
Electrical components or devices are generally connected in series whenever it is necessary to:
• control the amount of current flow in a circuit
• divide the total voltage of a supply
For example:
• Switches are connected in series with loads so that you can energize or de-energize different loads.
• Protective devices such as fuses and overload relays are connected in series with line conductors.
• By connecting equal values of resistance in series, the same voltage drop can be obtained across each resistance. Twenty Christmas tree lights connected in series to a 120 V supply would have a voltage rating of 6 V per light.
Disadvantages of series circuits
When designing a series circuit, consider these points:
• An open in any one device will also interrupt current flow to all remaining devices.
• A short in one device will cause an increase in current through all the devices.
• Changing the resistance value of one device will change the current, voltage, and power values of all remaining devices. | textbooks/workforce/Electronics_Technology/Book%3A_Electrical_Fundamentals_Competency_(Industry_Training_Authority_of_BC)/02%3A_Unit_II-_Common_Circuit_Components_and_Their_Symbols/06%3A_Wiring_Diagrams/6.01%3A_Symbols_Used_in_Schematic_.txt |
The parallel circuit is probably the most common type of circuit you will encounter. Loads in power distribution systems are usually connected in parallel with each other in one way or another. A parallel circuit is constructed by connecting the terminals of all the individual load devices so that the same value of voltage appears across each component. In Figure \(1\), you can see that each of the three resistors receives the same voltage from the source.
Figure \(2\) shows the more traditional schematic of the same circuit. Notice that:
• The total supply voltage appears across each of the three resistors.
• There are three separate paths (or branches) for current flow, each leaving the negative terminal of the supply and returning to the positive terminal.
The two fundamental characteristics of any parallel circuit are that:
• The voltage across each branch is the same.
• There is more than one path for the current to flow through.
In contrast to a series circuit, current still flows to the remaining devices in the circuit if any one branch or component in a parallel circuit is opened.
7.03: Voltage Sou
Multiple power sources can be connected in series or parallel in order to meet the different voltage or current output requirements for various applications:
• Power sources are connected in series to increase the voltage output.
• Power sources are connected in parallel to increase the current capacity
Series Sources
Voltage sources are sometimes connected in series to produce a higher voltage value. This is common in devices such as flashlights and portable transistor radios, in which 1.5 V battery cells are used.
To obtain a higher voltage output from series-connected sources, you must observe correct polarity. In Figure \(1\), a net voltage of 6 V is obtained if the individual 1.5 V cells are acting in the same direction. This is called series aiding.
For the voltages to accumulate, the negative terminal of one source connects in series with the positive terminal of the next source, and so on.
When voltage sources are connected in series opposing, the net voltage value is derived by subtraction. This is illustrated in Figure \(2\).
• Three of the cells are connected series aiding to produce 4.5 V.
• One cell is connected with opposite polarity of 1.5 V.
• The net voltage is 4.5 V – 1.5 V = 3 V.
• Overall polarity acts in the direction of the largest cell.
Parallel sources
Voltage sources are connected in parallel whenever it is necessary to deliver a current output greater than the current output that a single source of supply can provide, without increasing voltage across a load.
An advantage of parallel-connected power sources is that one source can be removed for maintenance or repairs while reduced power to the load is maintained. This is common in RVs that have dual batteries. For parallel batteries, current capacity is equal to that of one battery multiplied by the number of parallel batteries. If a 6 V battery has a maximum current output of 1 amp, and if it is necessary to supply a load requiring 2 amps, then you can connect a second 6 V battery in parallel with the first, as shown in Figure \(3\).
Whenever batteries or other power sources such as transformers or generators are to be connected in parallel, it is very important that the power sources have the following:
• The same terminal voltages
A lower voltage source connected to a higher one acts as a load itself, rather than helping share the real load current with the other sources of supply.
• Properly connected polarity.
Like terminals of the power sources must be connected together; that is, positive-to-positive and negative-to-negative. | textbooks/workforce/Electronics_Technology/Book%3A_Electrical_Fundamentals_Competency_(Industry_Training_Authority_of_BC)/02%3A_Unit_II-_Common_Circuit_Components_and_Their_Symbols/07%3A_Common_Circuit_Characteristics/7.02%3A_Parallel_Ci.txt |
Electrical energy to most individual and small commercial buildings in North America is distributed through a 120 V/240 V AC, single-phase, three-wire system.
Several advantages are gained by using this method of distribution:
• Copper conductor current requirements can be reduced.
• Two different voltages (120 V and 240 V) are available.
• Improved safety is established through grounding the neutral.
Source connections
A three-wire circuit is accomplished by connecting two 120 V sources in a series-aiding configuration. The conductor taken from the common point between the two sources is called the neutral conductor. Conductors taken from the two outer points are called the line or hot conductors.
As shown in Figure \(1\):
• Voltage measured line-to-line is 240 V.
• Voltage measured from either line to neutral is 120 V.
This allows connection to either 120 V loads (such as lighting) or 240 V loads (such as ranges or clothes dryers). See Figure \(2\).
Note that polarities shown in Figure \(1\) change every 120th of a second for a 60 hertz AC power supply.
For safety reasons, it is important that circuit conductors are identified by colour:
• Insulation on the two-line conductors is usually black (or sometimes one is black and one is red).
• The neutral always has white insulation.
The neutral is also grounded (directly connected to earth) at the source of supply.
Grounding the neutral conductor
Earth is a conductor of electricity. Therefore, to reduce the hazards of electrical shock and improve safety, electrical distribution systems usually have one of the circuit conductors connected to Earth, or as we say, grounded.
In most electrical systems, the neutral conductor is grounded at the supply by directly connecting it to Earth by another conductor (called the system grounding conductor) or by an electrode. Although grounding electrical distribution systems is an elaborate topic, consider the following simplified example.
Example
The fundamental purpose of grounding is to guard against electrical shocks and fire hazards. But what makes a grounded electrical system safer? Consider an ungrounded 120 V/240 V wiring system with a fault, as shown in Figure \(3\). Theoretically, if an insulation fault occurs at a piece of equipment (so that a line conductor makes accidental contact with the metal frame), nothing should happen. However, if an accidental ground should occur and a person comes in contact with the faulty equipment and ground, that person will experience a shock of 240 V (the line-to-line voltage).
Now look at the same wiring system with the neutral purposely grounded, as shown in Figure \(4\).
With the neutral grounded and the same equipment fault as previously described, the person coming in contact with both the metal frame of the equipment and the Earth would experience a shock of only 120 V (which is the line-to-neutral voltage). The shock voltage has been reduced by 50%.
To further minimize shock hazard, not only is the wiring system grounded but also all metallic, non-current-carrying parts of the equipment are grounded by using a bonding conductor. This is an important step if maximum safety is to be achieved.
As shown in Figure \(5\), if the equipment is also grounded intentionally, then a line-to-frame fault condition offers a low-resistance path for current flow back to the system neutral. Essentially this is a line-to-neutral short circuit, which causes the circuit overcurrent device to trip, thus eliminating the shock hazard from the system.
Although properly grounded wiring systems do not eliminate shock hazard, they certainly lower the odds of being shocked!
Now complete the Learning Task Self-Test.
7.E: Self-Test 3
Self-Test 3
1. Typical house wiring is an example of a series circuit.
1. True
2. False
2. If one load fails in a series circuit, what happens to the other loads?
1. They will all fail.
2. A fuse will blow.
3. Nothing happens.
4. The rest remain working.
3. As more resistors are added in series, what increases?
1. Power
2. Voltage
3. Current
4. Resistance
4. A series circuit allows the control of current flow.
1. True
2. False
5. Which of the following is true about a parallel circuit?
1. Voltage will be different at each load.
2. Voltage will be the same at each load.
3. Current will be the same at each load.
4. Resistance will be the same at each load.
6. The three-wire circuit is an example of which of the following?
1. Hot jumping
2. Series aiding
3. Parallel aiding
4. Backpacking circuit
1. For what purpose is a circuit grounded?
1. Safety
2. Series aiding
3. Circuit protection
4. Easier installation
2. What is the result of connecting three 6 V batteries in series?
1. 12 volts are produced.
2. 18 volts are produced.
3. 24 volts are produced.
4. The voltage doesn’t change.
3. Which of the following must apply to power sources connected in parallel?
1. Unlike terminals must be connected.
2. They must be connected with a fuse.
3. Like terminals must be connected.
4. They must have a transformer between them.
4. For voltages to accumulate in series aiding, what must occur?
1. Correct polarity
2. Circuit protection
3. Similar amperages
4. Dissimilar amperage
5. If two 12 V batteries are connected in parallel, what will the voltage be across any load?
1. 6 V
2. 12 V
3. 24 V
4. 48 V
08: Answer Key
Answer Key
Self-Test 1
1. Match the device on the left with its purpose on the right.
1. Circuit breaker (1. Protects circuits)
2. Rheostat (3. Variable control)
3. Relay (2. Electric switch)
4. Solenoid (4. Movable core)
2. a. They have two or more fixed values.
3. d. A circuit breaker can be reset and a fuse cannot.
4. b. False
5. b. Copper
6. a. True
7. d. Protection devices
8. b. 4
9. a. True
10. c. To increase or decrease voltage
11. c. CSA
12. a. True
13. c. 240 V
Self-Test 2
1. a. True
2. c. Pictorial
3. b. False
4. c. Installations
5. a. True
6. b. False
Self-Test 3
1. b. False
2. a. They will all fail.
3. d. Resistance
4. a. True
5. b. Voltage will be the same at each load.
6. b. Series aiding
7. a. Safety
8. b. 18 volts are produced.
9. c. Like terminals must be connected.
10. a. Correct polarity
11. b. 12 V | textbooks/workforce/Electronics_Technology/Book%3A_Electrical_Fundamentals_Competency_(Industry_Training_Authority_of_BC)/02%3A_Unit_II-_Common_Circuit_Components_and_Their_Symbols/07%3A_Common_Circuit_Characteristics/7.04%3A_Three-wire_.txt |
Learning Objectives
When you have completed the Learning Tasks in this Competency, you will be able to:
• define the terms used and explain the principles of soldering
• describe the methods for making properly soldered connections
• maintain soldering equipment
• use wireless connectors
It is important for you to be familiar with techniques for soldering electrical connections and how to use wireless connectors. For example, the ends of the finely stranded wires used for power supply cords on most portable power tools are soldered to permit a long-lasting, trouble-free connection. Solder also produces secure, durable electrical connections for switches, plugs, and tools. Wireless connectors are commonly used in many electrical applications because they are quick and easy to use.
Making tight electrical connections is critical to a safe wiring job. If wires come loose, you could get arcing and overheating, which could lead to a fire. The right connector is determined by a number of variables.
09: Wiring Connections
A material that allows energy to flow with relative ease is known as a conductor. The most common form of electrical conductor used is the wire. Most electrical wires are made from copper or aluminum and are in one of two forms: solid or stranded.
The term electrical cable usually refers to multiple insulated wires grouped in a common sheathing (Figure \(1\)).
Stranded conductors
Stranded wire is a collection of solid wires twisted or braided together, commonly around a central core (Figure \(2\)).
The current carrying capacity of a stranded wire is close to the current carrying ability of a single strand. Stranded wires act as a single conductor and carry a single electrical current. Stranded conductors are normally used in a thin wire that requires flexibility, such as speaker wire. Ordinarily, a stranded conductor has wires all the same size. The size of the strands used depends on the flexibility required. For example, #00 gauge cable may be made up of seven strands of #7 gauge wire, or 19 strands of #12 gauge, or 37 strands of #24 gauge, the last one being rated “extra flexible.”
Solid conductors
Solid wire consists of one strand of copper metal wire, bare or surrounded by an insulator. Solid wire is normally found in smaller sizes only. Solid wire is cheaper to manufacture than stranded wire and is used where there is little need for flexibility in the wire.
Insulating materials
The purpose of conductor insulation is to prevent unwanted flow of electrical current, such as ground faults, short circuits, or electric shock. There are various methods used to insulate conductors to satisfy the many conditions encountered in electrical installations, such as temperature, moisture, and different voltage
ratings. Insulating materials include:
• enamel coating
• rubber
• thermoplastics
• minerals
Stripping insulation
To make any type of electrical connection, you will need to expose the base wire from
the insulated covering. You can do this with wire strippers (Figure \(3\)).
With wire strippers, you can strip the amount of wire required for the type of connection being made. It is important to avoid damaging the copper wire by nicking the copper or cutting into it. Nicked wires can lead to overheating and eventually could cause an electrical fire.
Colour coding
Most electrical wiring circuits look complicated because several wires are found at any one point in the circuit. To make it easier to know exactly which is which, wires are identified by colour or labeled.
For building construction, the Canadian Electrical Code reserves two colours for specific applications:
When this system of colour coding is followed, at any point in any circuit, a white wire always indicates a neutral conductor. A green wire always indicates an equipment grounding conductor. Any other colour wires, such as red, black, or blue, can be assumed to be live or hot, meaning that they will have a voltage on the conductor and are therefore dangerous.
Wire size
Wires are manufactured in sizes according to the American Wire Gauge (AWG) system. The cross-sectional area of each gauge is an important factor for determining the current carrying capacity of a wire (ampacity). Increasing gauge numbers denote decreasing wire diameters, ranging from the largest 0000 (4/0) to the smallest, 44.
• White or natural grey covering is reserved for insulated, identified conductors, identified common conductors, and identified neutral conductors.
• Green covering is reserved for the equipment grounding conductor.
9.02: Soldered Connections
A variety of joints are used to prepare wires for soldering. These include:
• Western Union splice
• tap joint
• twist joint
Western Union splice
This splice joins the ends of two wires inline (compared to the twist joint below). Strip the wires for a length of 2.5 to 8 cm (1" to 3"), as shown in Figure \(1\). Clean the wire, then twist the ends of the wire tightly together as shown.
Tap joint
The tap joint (Figure \(2\)) connects a stranded wire to an intermediate point along the length of a second wire. Wrap the wire at least six times.
Twist joint
The twist joint (Figure \(3\)) is used to join parallel wires, whereas the Western Union splice is used to connect wires that are in line. Strip the insulation, clean the wires, and twist them together tightly for a length of 2.5 cm (1 in.).
Tinning stranded wire
In a general sense, tinning is the process of applying a thin layer of solder to something and will be discussed in more detail in Learning Task 2. In the case of stranded wire, you should tin the stripped ends of the wire to prevent the strands from separating while bending or connecting. Use only enough solder to make the stripped portion of the wire solid. The strands of the wire should be visible through the solder. Avoid solder from wicking in a wire underneath
the insulation because it will make the wire solid and cause it to break more easily. | textbooks/workforce/Electronics_Technology/Book%3A_Electrical_Fundamentals_Competency_(Industry_Training_Authority_of_BC)/03%3A_Unit_III-_Wiring_Connections/09%3A_Wiring_Connections/9.01%3A_Conductors.txt |
Soldering is the recommended way to splice, tap, or join wires to make a rigid, permanent, weather-resistant connection. The process of soldering can be time-consuming, awkward, restrictive, and expensive.
In many applications, soldering has been replaced by special connecting devices that simplify wire joining procedures. Solderless connectors are used on both wire and cable connections. Types of solderless connectors include:
• looped-end
• twist-on
• set-screw
• crimp-on
Looped-end connectors
The most common solderless connection has the looped end of a wire (Figure \(1\)) held in place by a set-screw at an electrical terminal (Figure 9). Note that the direction of the loop is the same as the direction the screw is turned when it is tightened (clockwise). The screw and washer should be made of corrosion-resistant materials such as copper or brass.
Twist-on connectors
The twist-on connector is a one-piece connecting device designed to splice aluminum or copper wires. Twist-on connectors are also known as wire nuts, wire connectors, cone connectors, thimble connectors, or Marrettes. Inside the blunt, bullet-like cover of the twist-on connector is a cone-shaped spring insert that threads itself onto conductors when the connector is twisted. When the connector is twisted onto the stripped ends of wires, the wires are drawn, twisted, and squeezed into the connector’s metal insert. Electrical continuity is maintained both by the direct twisted wire-to-wire contact and by contact with the metal insert.
Wing-like extensions (Figure \(5\)) are molded into some makes of connectors to reduce operator muscle fatigue when installing a large number of the connectors.
The shell of the twist-on connector provides sufficient insulation to allow these connectors to be used in circuits carrying up to 600 V.
Twist-on wire connectors are commonly colour-coded to indicate the connector size and, hence, their capacity (Figure \(6\)). They are commonly used as an alternative to soldering conductors since they are quicker to install and allow easy removal for future modifications, unlike soldered connections.
Twist-on connectors are not often used on wire gauges thicker than AWG #10 (5.26 mm²) because such solid wires are too stiff to be reliably connected with this method. Instead, set screw connectors, clamps, or crimp connectors are used.
Set-screw connectors
Set-screw connectors (Figure 13) consist of two parts:
• a brass connector body into which wires are inserted
• an insulated cone-shaped cap that is screwed onto the brass connector
The set-screw connector is most often used as a splice inside a protected electrical box and lighting fixtures. Although set-screws are more time-consuming to install and are more expensive than twist-ons, they may offer a more secure connection than twist-on connectors.
Crimp-on connectors
A crimp-on connector is used for a permanent tight splice. The crimp-on connector (compression connection) can have one or two parts.
The two-part connector (Figure \(8\)) has a conductor retaining sleeve that is compressed by using special crimping pliers and an insulated screw cap into which the crimped retainer is inserted.
The sleeve is composed of copper or zinc-plated steel, while the cap is a high dielectric substance. The zinc-plated steel retaining sleeve should not be used with aluminum conductors, as electrolysis can occur between the metals.
These devices are available in many sizes. As with other solderless connectors, each application must carefully select the correct size two-piece crimp-on connector.
The one-part crimp-on connector (Figure \(9\)) is commonly used as a terminal lug. Both the fork and the ring-type greatly simplify connecting stranded conductors to terminal screws. The crimp-on connector sometimes has a soft, hose-like tube that is molded to the connector. The connector and the insulation are crimped together. After crimping, the insulation returns to its original form.
Now complete the Learning Task Self-Test.
9.E: Self-Test 1
Self-Test 1
1. Which term best describes a material that allows electrical energy to pass through it?
1. Resister
2. Insulator
3. Conductor
4. Connector
2. Which of the following best describes the term electrical cable?
1. Any wire
2. Any insulated wire
3. Multiple wires grouped together in a common insulation
4. Multiple insulated wires grouped together in a common sheathing
3. What is the primary purpose of insulation on wires?
1. To protect the wire
2. To make installation easier
3. To prevent unwanted current flow
4. So the wire can be colour coded
4. When is stranded wire used?
1. On short wires
2. When cost is a factor
3. On straight runs of wire
4. When flexibility is needed
5. Wire is sized by gauge: the higher the number, the larger the wire.
1. True
2. False
6. What should be done to stranded wire prior to bending?
1. It should be curled.
2. It should be tinned.
3. It should be wound.
4. It should be twisted.
1. Solderless connections are more costly than soldering.
1. True
2. False
2. What is one advantage to a twist-on connector?
1. It is permanent.
2. One size fits all.
3. It will not come apart.
4. It can be removed easily.
3. It doesn’t matter what material the conductor is made from when making a connection.
1. True
2. False
4. What type of connector should be used to create a permanent splice?
1. Twist
2. Winged
3. Crimp-on
4. Set screw | textbooks/workforce/Electronics_Technology/Book%3A_Electrical_Fundamentals_Competency_(Industry_Training_Authority_of_BC)/03%3A_Unit_III-_Wiring_Connections/09%3A_Wiring_Connections/9.03%3A_Solderless_connectors.txt |
Most components are fitted with leads, pins, lugs, or some other means of interconnecting them electrically. Most soldering involves bonding these leads to other leads, circuit wires, copper pads, or other circuit parts. The primary purpose of soldering an electrical connection is to ensure an efficient flow of current between the joined parts.
Soldering properly is an important skill. Correct operation of electric circuitry depends on correct soldering. Poor soldering will often lead to poor operation of the circuit.
Safety
Your safety must always be a concern while you are soldering. There is a risk of inhaling fumes from soldering operations that can irritate the nose, throat, and lungs. Studies show that prolonged exposure to certain fumes may result in occupational asthma and contribute to chronic lung disease. In addition, fumes that you breathe may contain invisible particles, such as lead and zinc, that could cause poisoning. Always complete soldering operations in well-ventilated spaces. You should also carefully wash your hands before eating, drinking, or smoking. You should wear safety glasses with side shields to protect yourself from splashing solder.
10: Soldering Techniques
The soldering process depends on molten solder flowing into all the microscopic surface imperfections of the metals to be soldered and even penetrating very slightly below their surface. In this process, a chemical reaction occurs in which the solder actually melts some of the metals and alloys with them. Upon cooling, this combination of penetration and alloying results in a very strong bond between the solder and metal. When two pieces of metal are soldered together, a thin layer of solder adheres between them and completes the connection.
The process of surface penetration and alloying is known as wetting of the host metals (Figure 1). Some metals are very receptive to wetting and can readily be soldered, while others are non-receptive and cannot be soldered at all. Copper is very receptive to wetting by tin/lead solders. Tin also wets readily, as do silver and gold, but to a lesser extent. Solder wetting is displayed by a smooth, shiny flow of solder onto the metal surface. The process is often called tinning. Metals such as aluminum and iron will not wet properly. The solder forms stubborn flecks and balls and fails to penetrate or adhere. Effective solder bonding of these metals is not possible.
1. Wetting action
Solder flux
Solder wetting of metal is severely curtailed by the presence of surface oxides. This is one of the reasons aluminum cannot be tinned and soldered. Its surface is oxidized almost instantly by the presence of atmospheric oxygen. A clean, oxide-free surface cannot be obtained for soldering. Oxidization also restricts wetting of copper, so any copper parts to be soldered should be as clean as possible. Fortunately, copper oxidizes rather slowly, so surfaces cleaned by scraping or sanding will remain pure copper for some time before a tarnishing film of copper oxide reforms.
Unfortunately, oxidization is hastened by heat. Application of a heated soldering iron or molten solder will start surface oxidation, even on a freshly cleaned surface. For this reason, it is very hard to solder even clean copper without applying a soldering flux.
The primary function of a soldering flux is to eliminate oxidation during the soldering process. Flux melts and flows when heated, effectively sealing the surfaces against the entry of oxygen. Flux also lowers the surface tension of the molten solder, allowing it to flow and spread more easily. Flux contains a small quantity of an active antioxidant material, which serves as a mild cleaner to remove any surface tarnish.
Historically, soldering flux has been caustic liquids or pastes containing acids. This is because part of their function has been to scour and roughen the surfaces. The problem with acid flux is that it never completely vaporizes during heating and continues to corrode the metal surfaces indefinitely.
The flux most commonly used in electric soldering is rosin. Rosin is an organic material derived from certain tree saps. It is non-corrosive, reasonably non-toxic, and readily liquefied by heat. Its residues are also easily removed after soldering. Rosin flux is usually a continuous single or multiple core inside the wire solder (Figure 2). Because it melts at a much lower temperature than solder, rosin is readily dispersed onto the job both before and during the melting of the solder. Low-odour solder and solders without flux are available.
2. Flux-cored solder wire
Rosin core solder is the only kind you should use in electric work. Never use acid core or other solder containing corrosive flux. Never use any form of paste or liquid flux containing acid. Not only will the ongoing corrosion eventually cause mechanical deterioration, it will rapidly destroy the connection’s ability to conduct current.
Composition of solder
Solder is an alloy of different metals, commonly tin and lead, that have a lower melting point than the base metal. Both metals are reasonably good electrical conductors. The ratio of tin to lead has a great deal to do with the melting point and hardness of solder and also with its conductivity. Tin melts at about 327°C (620°F) and lead at about 232°C (450°F). When these metals are combined, the melting point of the mixture goes down. The melting point varies with the ratio of tin to lead, with the lowest occurring at about 183°C (360°F) for a 63/37 tin-lead mixture.
This lowest melting temperature is called the eutectic point. It marks the temperature at which the solder changes directly from solid to liquid with no semi-liquid or plastic state in between. Since a narrow plastic state is desirable in soldering operations, a 60/40 mix is very common. This raises the melting point slightly to about 188°C (370°F) and gives a temperature range for plasticity of about 4°C to 6°C (40°F to 43°F). It also produces optimum conduction characteristics and hardness for electronics soldering.
Note that the ratios for solder composition always state the tin content first.
60/40 solder is composed of 60% tin and 40% lead (by weight).
Wire solder is available in a variety of diameters. Which to use depends on the sizes of the component leads and terminals to be soldered. Diameters of 0.75 mm (1/16ø) and 0.38 mm (1/32ø) are the most commonly used sizes.
10.02: Soldering Tools
Soldering tools
Historically, heating the host metals and melting the solder was done by firing in a forge or by pouring molten solder onto the metals and wiping it into place with leather pads. Later, heat was applied by means of an iron bit that was heated in the forge. The name soldering iron has carried forward to this day. Today, heat is applied by various electrically heated soldering tools called irons or pencils or guns. Figure 3 shows two examples. The majority of electronic soldering done during electronic repair, for example, is completed with a low-wattage soldering pencil.
1. Some common soldering tools
2. Soldering tip shapes
Regardless of the shape, size, or design of the iron, the tip must be tinned. Tinning the tip is the process of applying a thin layer of solder to the tip to keep atmospheric oxygen and other contaminants off the soldering surface and help with the flow of the solder. A poorly tinned tip will make it virtually impossible to achieve a sound solder joint.
Soldering iron manufacturers specify an operating temperature range for each type of tip. This requires mating the heating capability of iron and tip. Insufficient iron capability will result in tip temperatures that are lower than needed for quality solder work or in rapid drop in tip temperature during soldering. Excessive heat will quickly deteriorate the tip and may possibly damage the components and printed circuit board being soldered.
You can estimate tip temperature by following this two-step process:
• Apply a small amount of solder to the flat surface of the tip and immediately wipe the tip with a damp cellulose sponge or paper towel.
• Observe tip colour immediately after wiping.
• If the color of the surface is silver, the temperature is between 315°C and 370°C (600°F and 698°F).
• If the tip shows gold streaks, the temperature is approaching 425°C (797°F).
The copper tips of irons and pencils are progressively dissolved by solder, and they soon become pitted and corroded. This is particularly true of the continuous-heat types. It is virtually impossible to do quality soldering with a corroded tip. Corroding can be slowed down by keeping the tip clean and well tinned.
Clean the tip by wiping it frequently with a damp cloth or cellulose sponge. The damp wipe will shock the built-up burned flux from the tip. Immediately re-tin the tip and leave a thin coating to keep atmospheric oxygen off the soldering surface. Wipe the excess solder off the tip before the next use. Reclean and recoat with solder when you finish each soldering task.
When pitting becomes significant, you should dress the tip and reshape it to clean metal with a fine file. This can be done with the tip hot so that the refreshed tip can immediately be re-tinned. Excess solder should be wiped away after re-tinning. Steel-clad tips suffer much less corrosion and should never be dressed with a file. Like copper tips, however, they should be cleaned frequently when hot. | textbooks/workforce/Electronics_Technology/Book%3A_Electrical_Fundamentals_Competency_(Industry_Training_Authority_of_BC)/03%3A_Unit_III-_Wiring_Connections/10%3A_Soldering_Techniques/10.01%3A_Solder_Bonding.txt |
Soldering techniques
To avoid soldering problems, it is extremely important to work with clean materials and the correct amount of heat. Soldering problems can normally be avoided by bringing the metals to soldering temperature quickly and completing the solder application in a short period of time. You know you have the proper heat when a joint can be completed in about two seconds. The heat will transfer most effectively to the work if a clean tip is lightly tinned with a film of solder. The film of solder will create a bridge between the iron and soldering surfaces by flowing into all gaps. Sometimes a small amount of solder must be added to help form this bridge by applying a small drop to the iron’s tip before applying it to the work surfaces.
Although learning the theories of good soldering is important in developing soldering skills, good soldering is primarily learned through practice. Holding the iron and applying it and the solder to the work surface must be done using techniques that are comfortable and natural to each individual. How you do the job is unimportant as long as the end result is a quality soldered joint with no damage to the surrounding components and materials. At every opportunity, you should experiment with different techniques, always making certain that your soldering meets the requirements of effective soldering listed earlier.
Procedures
To solder effectively, follow these procedures:
1. Follow safety precautions.
Always wear safety glasses with side shields when soldering. Ensure adequate ventilation or use solder fume extraction hoods to prevent accumulation of solder fumes. Wear closed-toed shoes and clothing made of natural fibres, with long sleeves and long trouser legs to protect against burns from solder splashes.
Avoid touching the solder pencil tip or freshly soldered joints. Use an iron holder and allow the iron to cool completely before putting it away. Never solder on equipment that has power supplied to it. Before eating, drinking, or smoking, always wash your hands to avoid accidentally ingesting lead.
2. Clean and tin host materials.
The materials to be soldered (leads, pads, terminals, etc.) must be clean and tinned. Inspect all host metals and clean them to remove contaminants such as oxides, machine oil, hand lotion, and skin oils. Avoid touching cleaned surfaces.
Most component leads and hookup wires are factory tinned. Copper parts and solder pads that are untinned should be cleaned and tinned separately.
To tin a surface, clean it and then heat the surface with a soldering tip. Apply the solder to the surface and allow a thin coating to form on the surface. Allow the surface to cool.
When tinning stranded insulated wires, strip the wire to the appropriate length for the joint being made. Tin the wire, using only enough solder to make the stripped wire solid. The strands of wire should be visible through the solder. Avoid solder from wicking in the wire underneath the insulation.
When tinning and soldering, make a solder bridge to increase the linkage area and speed heating of the surface or joint (Figure 5).
1. Cross-section view of iron tip on a round lead - “X” shows point of contact
1. Form a mechanical joint between the host metals.
2. Needle-nose pliers used as a heat sink
1. Allow the connection to cool undisturbed.
3. Steps to solder conductors to turret terminals
4. Soldering procedures for cup terminals
5. Correctly soldered connection
Soldering defects
The following characteristics are unacceptable in a solder joint:
• charred, burned, or melted insulation or parts
• excessive solder, including peaks, icicles, and bridging
• flux residue, solder splatter, or other foreign materials on circuitry of adjacent areas
• insufficient solder
• pits, holes, or voids or exposed base metal in the soldered connection
• fractured or cracked solder connection or evidence of grain change
• cut, nicked, gouged, or scraped conductors
• improper conductor length
During the soldering process, you must be very careful to avoid defects in the solder joint itself. Soldering defects primarily reduce the efficiency of the electrical connection between the metals to be joined.
Cold solder joint
A cold solder joint occurs when the component leads have not been heated sufficiently. A lack of heat in the metals to be joined will reduce or eliminate proper wetting of the surfaces, as described earlier. Insufficient wetting will cause the solder to pile up on the joint surface rather than flow smoothly through the joint. An efficient electrical connection between the metals to be joined will not be made, resulting in resistance to current flow through the joint.
Cold joints commonly result from applying solder to the soldering iron’s tip rather than to the joint to be soldered. When the solder is touched to the iron rather than to the joint, the solder will melt before the joint has heated sufficiently. The melted solder will flow over the joint, but will not properly wet it. Unless heat is maintained well after the solder flows over the joint, a cold solder joint will usually occur.
The major indicator of a cold solder joint is a frosty appearance to the surface of the solder. In some instances, reheating the joint adequately will correct a cold joint. If the surface stays frosty, the used solder must be removed and the joint resoldered using correct procedures.
Fractured joint
A fractured joint occurs during the cooling process when the soldered joint is moved while the solder is in its plastic state. Movement during the plastic state will have a crystallizing effect on the solder and a very rough, inefficient joint will result.
The usual cause of a fractured joint is a poor mechanical connection of the metals before soldering begins. Components must be mounted firmly before soldering begins.
Reheating usually cures a fractured joint, but the addition of a small amount of fresh solder may be needed to reflux the exposed metals.
Rosin joint
A rosin joint occurs when part of the joint has been heated enough to melt the flux and coat the metals, but not enough to cause the solder to flow. The covering of flux acts as an insulator and consequently provides a very poor electrical connection or no connection at all.
Reheating and applying a small drop of fresh solder will often cure a rosin joint.
Now complete the Learning Task Self-Test.
10.E: Self-Test 2
Self-Test 2
1. Safety factors such as toxic fumes and splashing flux should always be addressed when soldering.
1. True
2. False
2. Which of the following best describes the process of surface penetration?
1. Bonding
2. Wetting
3. Soldering
4. Prepping
3. Which of the following should apply when tinning stranded wire?
1. The strands should be thickly coated.
2. The strands should be visible under the solder.
3. The solder should wick up underneath the insulation.
4. A large blob of solder should form at the end of the wire.
4. Metals like aluminum and iron wet easily.
1. True
2. False
5. What is the purpose of flux?
1. To remove oxides
2. To clean the metal
3. To assist with heating
4. To remove the solder
6. What is the most common alloy used for solder?
1. Tin-lead
2. Lead-silver
3. Tin-copper
4. Lead-copper
1. Soldering pencils are used for heavy-duty applications.
1. True
2. False
2. What must be done to a soldering tip prior to soldering?
1. Tin it.
2. Wash it.
3. Wire brush it.
4. Heat it red hot.
3. What should be done to an overly corroded soldering tip?
1. Nothing.
2. Re-tin it.
3. Throw it away.
4. Dress it with a fine file.
4. What is the purpose of a heatsink?
1. To protect the solder
2. To pull flux to the joint
3. To pull heat to the area for soldering
4. To pull heat away from certain components
5. What would cause a solder joint to be piled up and lumpy in appearance?
1. Insufficient heat
2. Lack of flux
3. Poor tinning
4. A corroded tip
11: Answer Key
Answer Key
Self-Test 1
1. c. Conductor
2. d. Multiple insulated wires grouped together in a common sheathing
3. c. To prevent unwanted current flow
4. d. When flexibility is needed
5. b. False
6. b. It should be tinned.
7. b. False
8. d. It can be removed easily.
9. b. False
10. c. Crimp-on
Self-Test 2
1. a. True
2. b. Wetting
3. b. The strands should be visible under the solder.
4. b. False
5. a. To remove oxides
6. a. Tin-lead
7. b. False
8. a. Tin it.
9. d. Dress it with a fine file.
10. d. To pull heat away from certain components
11. a. Insufficient heat
14: Answer Key
Answer Key
Self-Test 1
1. c. Resistance
2. b. False
3. b. 2.2 V
4. b. False
5. c. A negative voltage would be read.
6. c. Using the one-hand technique
7. b. False
8. b. False
9. a. Series
10. c. After checking resistance
11. a. 0
12. c. 2125 Ω
13. c. Continuity test
Self-Test 2
1. c. 50 mA
2. a. Open
3. d. The load has failed.
4. c. The wiring has failed.
5. a. The load has failed.
6. d. Turn the circuit power off.
7. b. Continuity test
8. a. Voltage | textbooks/workforce/Electronics_Technology/Book%3A_Electrical_Fundamentals_Competency_(Industry_Training_Authority_of_BC)/03%3A_Unit_III-_Wiring_Connections/10%3A_Soldering_Techniques/10.03%3A_Soldering_techniques.txt |
To have a good grasp of electrical theory it is important to have a grasp of trigonometry. Whether we are talking about single phase or polyphase power, trigonometry is a key concept. The first part of this textbook will look at one of the most basic parts of trigonometry: the triangle.
• 1.1: Angles
Before we even get into trigonometry, we need to discuss angles.
• 1.2: Triangles
Learning about electrical theory necessitates the study of triangles. More specifically: right triangles. Before we dig too much into the right triangle, let’s go over two key points about triangles: All triangles have three sides and All triangles contain 180 degrees.
• 1.3: Pythagoras
The Pythagorean theorem, also known as Pythagoras’ theorem, is a relation in Euclidean geometry among the three sides of a right triangle. ‘It states that the square of the hypotenuse (the side opposite the right angle) is equal to the sum of the squares of the other two sides.
• 1.4: Naming Right Triangle Sides
Trigonometry is the study of the relationship that exists between the sides and the angles of a triangle.
• 1.5: Trigonometry Functions
When determining the designate angle we can use different ratios of sides: (1) We can use a ratio of the opposite to the hypotenuse. (2) We can use a ratio of the adjacent to the hypotenuse. (3) We can use a ration of the opposite to the adjacent.
• 1.6: Power and Impedance Triangles
When dealing with DC circuits the only thing that opposes current is the resistance in the circuit. As we will learn in later units, AC adds a component that opposes current as well. This is called reactance and it runs 90 degrees to the circuit resistance. This means it is not possible to add them together arithmetically; it has to be done using the Pythagoras’ theorem. When you add these two together, you get a total opposition to current flow called impedance.
01: Trigonometry
What’s the deal with angles anyway?
Before we even get into trigonometry, we need to discuss angles. Don’t worry. Things are not going to get too crazy. I promise. Let’s go over the basics first.
Degree. One-three-hundred-and-sixtieth of the circumference of a circle. It is also the unit by which we measure angles.
Figure 1. Degrees
Angle. This is the space between two intersecting lines.
Figure 2. Angle
Complementary angles. These are two angles whose sum equals 90 degrees.
Figure 3. Complementary angle
Supplementary angles. These are two angles whose sum equals 180 degrees.
Figure 4. Supplementary angle
Acute angle. An angle that is less than 90 degrees.
Figure 5. Acute angle
Obtuse angle. An angle that is greater than 90 degrees.
Figure 6. Obtuse angle
Similar angles. It is possible for triangles to each have different sized sides but share the same sized angles. These are called similar angles.
Figure 7. Similar angles
Right angle. This is an angle that is 90 degrees.
Figure 8. Right angle
There is a ton of information about angles that we don’t need to get into. Remember: Try not to overcomplicate things. Just focus on the basics and you’ll be fine.
1.02: Triangles
Why triangles are important
Learning about electrical theory necessitates the study of triangles. More specifically: right triangles. Before we dig too much into the right triangle, let’s go over two key points about triangles.
• All triangles have three sides. (File this fact under the “thank you Captain Obvious” category.)
• All triangles contain 180 degrees.
Figure 9. Triangle
Different triangles
The right triangle is the most common triangle that will be used in electrical theory. It is a good idea to have a basic understanding of other triangles as well. Here are some common triangles you will come across in trigonometry.
Isosceles triangle. This triangle has two sides that are equal, and two angles that are equal.
Figure 10. Isosceles triangle
Equilateral triangle. All three sides of this triangle are equal, and all three of its angles are equal too.
Figure 11. Equilateral triangle
Similar triangles. These triangles each have different sized sides, but they share the same sized angles.
Figure 12. Similar triangles
So what about these right triangles you were talking about?
A right triangle is a triangle that has one right angle (equal to 90 degrees). This means that the other two angles are complementary, that is, they must add to 90 degrees.
Figure 13. Complementary angles.
Ok, so what does a right triangle have to do with electrical?
Quite a bit actually. In the world of electrical theory, we will have to add up values. We call these units vectors (more on the concept of vectors in a later chapter). These vectors each head in a different direction. In fact, they are 90 degrees to each other. When we add them, the sum of these two vectors ends up being the point between the two sides.
Figure 14. Vector triangle
Because they are not heading in the same direction (they are heading in directions that are 90 degrees to each other) we can’t add them up normally. They have to be added vectorially. How do you do this? I’m glad you asked. | textbooks/workforce/Electronics_Technology/Book%3A_Trigonometry_and_Single_Phase_AC_Generation_for_Electricians_(Flinn)/01%3A_Trigonometry/1.01%3A_Angles.txt |
Who is this Pythagoras and why does he matter?
Pythagoras was a Greek philosopher who lived around 500 BC. He is credited as being a philosopher and mathematician. Much of what we know of Pythagoras is from writings that were copied down hundreds of years after his death, so the validity of what we do know is questionable. He is credited with Pythagoras’ theorem when actually it has been proven that Babylonians and Indians were using variations of it for hundreds of years before he even came along. More can be found about him in this article.
Thanks for the history lesson, but get on with it!
The Pythagorean theorem, also known as Pythagoras’ theorem, is a relation in Euclidean geometry among the three sides of a right triangle. ‘It states that the square of the hypotenuse (the side opposite the right angle) is equal to the sum of the squares of the other two sides.
It’s not as bad as it seems. Basically, the Pythagoras’ theorem says that you can figure out any side of a right triangle as long as you have the other two sides, using the equation:
\[A^2 + B^2 = C^2\]
When we look at the formula, there is one important thing to remember: \(C\) is always the longest side. \(A\) and \(B\) can be swapped around, but when using this formula, \(C\) is always the longest side (which is also the side opposite the 90-degree angle).
Figure 15. Longest side triangle
Video! This video walks through how to apply Pythagoras’ theorem on a right triangle.
1.04: Naming Right Triangle Sides
What is this big fancy word, trigonometry?
Trigonometry is the study of the relationship that exists between the sides and the angles of a triangle.
That sounds complicated and scary.
It can be, but lucky for us we are only dealing with right triangles. This makes it very simple and almost fun. (Nerd alert!)
First steps
We have already learned how to determine the sides of a triangle using the Pythagoras’ theorem. Next up is using those sides to determine the angles. Lucky for us we know that in a right triangle we already have one 90-degree angle. We also know that if we can solve any of the other two angles, the third one is easy. (All triangles have 180 degrees.) Our next step is to name the sides of the triangle. The names of these sides are dependent on something called the designate angle or theta. Theta is an angle that you determine or is determined for you.
Figure 16. Theta 1
Figure 17. Theta 2
Now once you have figured out which angle is your theta, we can get to business naming the sides.
Adjacent. This is the side that sits adjacent to the designate angle.
Opposite. This is the side that sits opposite to the designate angle.
Hypotenuse. This is the side that sits opposite the 90-degree angle.
The hypotenuse is always the longest side of the triangle and doesn’t care where the designate angle is. It only cares that it is opposite the 90-degree angle.
Figure 18. Hypotenuse
And if we switch the designate angle, the names of the sides change as in Figure 19.
Figure 19. Adjacent and Opposite sides switch places
The next chapter tells us what to do with these names. | textbooks/workforce/Electronics_Technology/Book%3A_Trigonometry_and_Single_Phase_AC_Generation_for_Electricians_(Flinn)/01%3A_Trigonometry/1.03%3A_Pythagoras.txt |
When determining the designate angle we can use different ratios of sides.
• We can use a ratio of the opposite to the hypotenuse.
• We can use a ratio of the adjacent to the hypotenuse.
• We can use a ration of the opposite to the adjacent.
Each ratio has a trigonometric function that helps turn the ratio into an angle. They are:
• sin θ = opposite/hypotenuse
• cos θ = adjacent/hypotenuse
• tan θ = opposite/adjacent
One way of remembering the ratios are these mnemonics:
• SOH – Sine is opposite/ hypotenuse
• CAH – Cosine is adjacent/hypotenuse
• TOA – Tangent is opposite/ adjacent
By the way,
• sin is short for sine
• cos is short for cosine
• tan is short for tangent
Video!
This video walks through how to determine the angle of a right triangle when you have two sides.
A YouTube element has been excluded from this version of the text. You can view it online here: https://pressbooks.bccampus.ca/trigf...tricians/?p=34
1.06: Power and Impedance Triangles
What is going on here?
This is the point where I am going to ask you to take my hand and to trust me. Okay, you don’t have to take my hand, but you do have to trust me. We are going to start using some terms before totally going into the theory behind them. I promise that we will get more in-depth into these concepts in future lessons.
Impedance triangles
When dealing with DC circuits the only thing that opposes current is the resistance in the circuit.
Figure 20. DC resistive circuit
As we will learn in later units, AC adds a component that opposes current as well. This is called reactance and it runs 90 degrees to the circuit resistance. This means it is not possible to add them together arithmetically; it has to be done using the Pythagoras’ theorem. When you add these two together, you get a total opposition to current flow called impedance.
Figure 21. DC inductive circuit
The triangle that is created when adding the resistance to the reactance is known as an impedance triangle.
Figure 22. Impedance triangle
In an impedance triangle, the resistance (r) is always on the bottom of the triangle, the reactance (x) always goes on the side and the hypotenuse is always the impedance (z).
Power triangles
When dealing with a purely resistive circuit, the power being dissipated is in the form of heat or light and is measured in watts and is known as true or active power. It is a product of I2R.
Figure 23. Resistive power circuit
In an AC circuit with inductance, watts are still present. There is also a reactive power present as current passes across the reactance. This power is called reactive power and is also called wattless or quadrature power. Its unit is the Vars.
Figure 24. Inductive power circuit
Much like the impedance triangle, we can not just add the two powers together to get overall power. They must be added using the Pythagoras’ theorem. Their sum is equal to the apparent power (VA).
Figure 25. Power triangle
When calculating for reactive power, we are still able to use the power formulas. We just have to use them with reactance instead of resistance.
• I2X = Vars
• E2 (inductor voltage) /X = Vars
• I x E (inductor voltage) = Vars
Remember
When building an impedance or power triangle, the resistive component always goes on the bottom of the triangle and the reactive component always goes on the side. | textbooks/workforce/Electronics_Technology/Book%3A_Trigonometry_and_Single_Phase_AC_Generation_for_Electricians_(Flinn)/01%3A_Trigonometry/1.05%3A_Trigonometry_Functions.txt |
• 2.1: A Vector Primer
A vector is a quantity that possesses magnitude and direction. As an example, let’s say I roundhouse kicked you in the head. The magnitude of the force and the angle at which I kicked you would be a vector.
• 2.2: Quadrants
A quadrant is a circle cut into four parts.
• 2.3: Polar vs. Rectangular Form
When dealing with vectors, there are two ways of expressing them. Up to this point, we have used a magnitude and a direction such as 30 V @ 67°. This is what is known as the polar form. It is more often the form that we like to express vectors in.
• 2.4: Vector Addition
When adding vectors, we have to find some common ground. This is why we focus on the X and Y coordinates. Each vector can be broken down into X and Y coordinates. This allows us to find some common ground as the X coordinates are heading in the same direction and the Y coordinates are heading in the same direction.
Thumbnail: Vector in a Cartesian coordinate system. (CC BY-SA 4.0 unported; Acdx).
02: Vectors
What is a vector?
A vector is a quantity that possesses magnitude and direction. As an example, let’s say I roundhouse kicked you in the head. The magnitude of the force and the angle at which I kicked you would be a vector. I know what you’re thinking: “This electrical stuff sounds cool.” And you’d be right.
Image retrieved from pixabay.com. Used under Creative Commons CC0 license.
Aside from helping me become a fighting machine, how do vectors have anything to do with electricity?
AC values are constantly changing magnitude and direction. We will talk about this more in-depth in the AC generation portion of the course. Eventually, we will be required to add these values together. The sum of the vectors is called the resultant. This is all well and good when vectors are heading in the same direction…
Figure 26. Vectors in the same direction
… because you can just add them together.
Figure 27. Vectors in the opposite direction
It isn’t even bad if they are heading in the opposite direction. You can just subtract them. The only thing when adding them in opposite directions is that you have to pay attention to which vector has the greatest value. This will become the new direction of the sum of the vectors.
The problem arises when they are heading in completely different directions.
Figure 28. Vectors moving in different direction
How did you do that?
Trust me, it is not difficult. In order to figure out how to add vectors, we first have to talk about the quadrant system.
2.02: Quadrants
Like a Star Trek quadrant?
First off: Nerd alert!
Secondly, yes, a quadrant is a circle cut into four parts.
What does this have to do with electricity?
Voltage and currents are constantly changing magnitude and direction. When changing direction, they actually rotate in a counterclockwise direction. They are tethered to a point of origin.
Figure 29. Quadrant point of origin
Each quadrant contains certain directions.
• Quadrant 1 has 0 to 90 degrees.
• Quadrant 2 has 90 to 180 degrees.
• Quadrant 3 has 180 to 270 degrees.
• Quadrant 4 has 270 to 360 degrees.
This is very important as it helps us to determine which vectors belong in which quadrant.
Polarity
It is also important to understand polarity when dealing with quadrants. A quadrant system is basically an X-Y graph. We use the point of origin as a reference point. On the X axis, anything to the right of the point of origin is positive and anything to the left is negative. On the Y axis, anything above the point of origin is positive and anything underneath it is negative. This means each quadrant has its own polarity, as shown in Figure 30.
Figure 30. Quadrant polarity
This too is extremely important when it comes to adding vectors.
Are you getting excited yet? This is all going to come together in one magical dance.
Video! This video goes into greater detail about the specifics of all four quadrants. | textbooks/workforce/Electronics_Technology/Book%3A_Trigonometry_and_Single_Phase_AC_Generation_for_Electricians_(Flinn)/02%3A_Vectors/2.01%3A_A_Vector_Primer.txt |
Polar form
When dealing with vectors, there are two ways of expressing them. Up to this point, we have used a magnitude and a direction such as 30 V @ 67°. This is what is known as the polar form. It is more often the form that we like to express vectors in.
Rectangular form
Rectangular form breaks a vector down into X and Y coordinates. In the example below, we have a vector that, when expressed as polar, is 50 V @ 55 degrees. The first step to finding this expression is using the 50 V as the hypotenuse and the direction as the angle. Next, we draw a line straight down from the arrowhead to the X axis. What does this look like to you? If you said right triangle, give yourself a pat on the back. We then can use the angle and the hypotenuse to determine the X axis with these equations:
• cos 55°×50 = 28.7 for the X axis
• sin 55°×50 = 41 for the Y axis
This is accomplished just by transposing the ratios from what we learned previously in trigonometry.
Figure 31. Quadrant 1
We then can express the same vector as 28.7, j 41.
Where did that j come from?
The letter j is put in front of the y component to indicate the difference between the X and the Y. The reason j is used is this.
As a way of telling the difference between X and Y, it was decided that a letter should be put in front of the Y. The X and Y components don’t really exist, and are referred to as imaginary numbers. Because each is an imaginary number, the letter i was suggested. However, the letter i is also used as a symbol for current, so it was decided to go with the letter j instead.
Why polarity is important
Let’s look at another example. The polar form is 60 V @ 140 degrees. This puts the vector in the second quadrant.
In the second quadrant, X is – (negative) and Y is + (positive). The angle of 140° is used from the 0° point. To use trigonometry, we need to determine what the angle is in reference to the X axis. In this example, it is 40° (the supplement of 140°). After that, we can use trigonometry to determine the X and Y components.
• cos 40°×60 = 46 for the X axis
• sin 40°×60 = 39 for the Y axis
Figure 32. Quadrant 2
If we are going to express it in rectangular form, use -46, j39. Remember that the X component is negative and the Y component is positive as they are in the second quadrant.
Video! This video walks through how to convert from polar form to rectangular form.
2.04: Vector Addition
A quick recap
There was a fair bit to wrap our heads around before we finally got into vector addition. Here are some of the key points:
• Vectors contain magnitude (resultant) and direction (angle).
• Each vector can be broken into X and Y coordinates.
• We must use a quadrant system to chart the X and Y coordinates.
• Pay attention to the polarity (what quadrant is it in?).
• Vectors can be expressed in the polar form (resultant and angle) or rectangular form (X and Y coordinates).
• Base your angle off of the X axis.
• When converting from rectangular to polar, it is extremely important to pay attention to what quadrant you are in.
• Quadrant 1 is the angle you calculate.
• Quadrant 2 is 180 minus the angle you calculate.
• Quadrant 3 is 180 plus the angle you calculate.
• Quadrant 4 is either 360 minus the angle you calculate, or, put a negative in front of the angle you calculate.
Okay, let’s learn how to add vectors.
Adding vectors
When adding vectors, we have to find some common ground. This is why we focus on the X and Y coordinates. Each vector can be broken down into X and Y coordinates. This allows us to find some common ground as the X coordinates are heading in the same direction and the Y coordinates are heading in the same direction. Let’s look at the example in Figure 39.
In this example, we have one vector that is 38 V @ 20 degrees and another that is 100 V @ 135 degrees.
Figure 39. Adding vectors
The first step is to draw in the X and Y axes. (See Figure 40.) This will help provide us with a reference when determining our X and Y coordinates.
Figure 40. Adding vectors draw quadrant
Next we will work out the X and the Y for each vector, in Figure 41.
Figure 41. Adding vectors determining X and Y
Next add an X-Y chart and enter the coordinates (Figure 42).
Figure 42. Adding vectors X and Y chart
Add up your X coordinates and your Y coordinates and you have your answer in rectangular form (Figure 43).
Figure 43. Adding vectors for rectangular form
Take your rectangular form and chart it on its own (Figure 44).
Figure 44. Adding vectors for polar form
Take the resultant and the angle, and convert it to polar form: 90.6 @ (180°−68°)90.6 @ 112°.
There you have it. If you have more vectors, you just keep adding other rows to your X-Y chart.
Video! This video walks through how to add vectors heading in completely different directions. | textbooks/workforce/Electronics_Technology/Book%3A_Trigonometry_and_Single_Phase_AC_Generation_for_Electricians_(Flinn)/02%3A_Vectors/2.03%3A_Polar_vs._Rectangular_Form.txt |
• 3.1: Electromagnetic Induction
Electromagnetic induction is when a voltage is created by passing a conductor through a magnetic field.
• 3.2: The Alternator
We have established that if we have a conductor pass through a field or a field through a conductor a voltage is established. This means that voltage is only established when there is constant motion. Instead of having someone passing a conductor through a field rapidly, it was discovered that the conductor could be formed into a loop and rotated through the field to maintain a voltage. This would be an example of what is known as a simple alternator.
• 3.3: How a Waveform Is Generated
Any time you pass a conductor through a magnetic field, you induce a voltage. If we take that conductor and turn it into a loop and spin it continually through that magnetic field, we have created an alternator. This means that a voltage will constantly be induced. However, this is not a flat line voltage like direct current. It creates an oscillating voltage that rises and falls.
• 3.4: AC Waveform Analysis
Well, it turns out that there is an awful lot going on in that waveform. Most of it is actually useful as well.
• 3.5: Frequency and Alternators
In the last chapter, we learned the term cycle means from the point in a waveform to where the waveform starts to repeat itself. When we discuss the term frequency, we are referring to how many cycles can occur in one second. Frequency is measured in hertz or CPS (cycles per second). Two factors affect the frequency in an alternator: rotation speed and the number of poles.
Thumbnail: Simple Alternator
03: AC Generation
What is this electromagnetic induction of which you speak?
Electromagnetic induction is when a voltage is created by passing a conductor through a magnetic field.
Figure 45. Magnetic poles and induction
The size of the voltage can be varied by three factors:
1. The size of the magnetic field. The more flux lines there are, the more flux lines there are for the conductor to cut. The strength of flux is directly proportional to the induced voltage.
2. The active length of the conductor. Active length meaning the part of the conductor that actually passes through the field. The active length is directly proportional to the induced voltage.
3. The speed at which the conductor passes through the field. The faster the conductor passed through the field, the greater the voltage induced. The speed is directly proportional to the induced voltage.
These relationships to voltage can be broken into this formula:
\[e = βlv.\]
Where:
• \(e\) = peak voltage induced in the inductor (volts)
• \(B\) = field strength between the poles (Tesla)
• \(l\) = active length of conductor (meters)
• \(v\) = velocity of the conductor through the field (m/sec)
Example \(1\):
A conductor that has an active length of 4 meters passes through a field of 5 Tesla at a speed of 15 meters per second. Determine the peak voltage induced on this conductor.
Solution
(4 m)(5 T)(15 m/sec) = 300 volts peak
That’s crazy! Who discovered that? The discovery of electromagnetic induction is attributed to Michael Faraday who discovered that when he passed a magnetic field through a conductor a current would flow. As long as there was motion between the field and the conductor, a voltage could be induced. This could mean the conductor passes through a field or a field passed through a conductor. | textbooks/workforce/Electronics_Technology/Book%3A_Trigonometry_and_Single_Phase_AC_Generation_for_Electricians_(Flinn)/03%3A_AC_Generation/3.01%3A_Electromagnetic_Induction.txt |
How do we keep the voltage coming?
We have established that if we have a conductor pass through a field or a field through a conductor a voltage is established. This means that voltage is only established when there is constant motion. Instead of having someone passing a conductor through a field rapidly, it was discovered that the conductor could be formed into a loop and rotated through the field to maintain a voltage. This would be an example of what is known as a simple alternator.
A simple alternator has two magnetic poles that establish a magnetic field. The conductor (armature) rotates through this field to establish a voltage.
Figure 46. Simple alternator
A practical alternator has a stationary conductor and the field rotates.
Figure 47. Practical alternator
What are the parts of the alternator?
Figure 48. Simple alternator parts
Figure 49. Practical alternator parts
Armature. This part is what the voltage is induced on to. It can be rotating (simple alternator) or stationary (practical alternator).
Slip rings. Made of brass, they rotate and either bring current to the load (simple alternator) or excitation to the field (practical alternator).
Brushes. Made of graphite carbon, they are stationary and either pass current to the load (simple alternator) or current to the field (practical alternator).
Field poles. They are either stationary (simple alternator) or rotating (practical alternator).
Prime mover. This part spins the armature (simple) or the field (practical). Examples include:
• combustion engine
• hydro dam
• hand crank
• windmill
Which is better the simple or the practical?
If you guessed the practical, you would be right. The brushes of a simple alternator have to be sized for the load. If you have a large load that draws a lot of current, then your brushes would have to be sized accordingly. Whereas, with the practical alternator the brushes bring current to the field and can be small yet still allow enough current to adjust the field. With either alternator, the easiest way to adjust the voltage is by varying the field strength. It is possible to vary the speed on the alternator to adjust the voltage, but this will also change the frequency.
3.03: How a Waveform Is Generated
AC generation with an alternator
If Faraday has taught us anything it is this: Any time you pass a conductor through a magnetic field, you induce a voltage. If we take that conductor and turn it into a loop and spin it continually through that magnetic field, we have created an alternator.
Figure 50. Alternator picture
This means that a voltage will constantly be induced. However, this is not a flat line voltage like direct current. It creates an oscillating voltage that rises and falls.
Is this what you mean by sine wave generation?
Yup, this is exactly what I mean. As the conductor spins through the field, there will be times that it does not cut any lines of flux. There will be times when it cuts some of the lines of flux, and there will be times that it is cutting the maximum amount of flux lines that it can. This means that at some point during the sine wave generation there will be no voltage generated. Then there will be some voltage generated, and then there will be a maximum voltage generated. This creates this thing of beauty. A sine wave.
Figure 51. Sine wave
Oh yeah, I think I have seen that before
This wave pattern occurs often in nature, including ocean waves, sound waves and light waves. In fact, if you take the hours of daylight in a day and graph it out with the months of the year, guess what? A sine wave is generated. If you’d like to read an interesting article on the seasons and sine wave generation, read Calculus of the seasons. Isn’t nature cool? But I digress. This sine wave is extremely important when it comes to electrical generation. Future postings will discuss its importance and go into in-depth analysis of the waveform.
Video! This video explains how a sine wave is generated in an alternator. | textbooks/workforce/Electronics_Technology/Book%3A_Trigonometry_and_Single_Phase_AC_Generation_for_Electricians_(Flinn)/03%3A_AC_Generation/3.02%3A_The_Alternator.txt |
What fun can we have with that waveform?
Well, it turns out that there is an awful lot going on in that waveform. Most of it is actually useful as well.
Video! This video shows all that is happening in the sine wave.
To Recap
• Average (1 alternation) = .639 × peak
• Instantaneous = sin θ × peak
• Effective (RMS) = .707 × peak
3.05: Frequency and Alternators
In the last chapter, we learned the term cycle means from the point in a waveform to where the waveform starts to repeat itself. When we discuss the term frequency, we are referring to how many cycles can occur in one second. Frequency is measured in hertz (shout out to Heinrich Hertz) or CPS (cycles per second). Two factors affect the frequency in an alternator: rotation speed and the number of poles.
Figure 52. Sine wave cycle
Rotation speed
As the armature rotates through the field, it starts to create a waveform (as we saw in the last chapter). One full mechanical rotation of the armature creates one full sine wave on a two-pole alternator. If the two-pole alternator spins three complete revolutions in one second, it will create three full sine waves in that one second. We would say that the frequency is at three cycles per second or three hertz (as the cool kids say).
A machine’s rotational speed is measured in rotations per minute or RPM. However, we are not concerned with minutes, but rather, with seconds when dealing with frequency. Therefore, RPM must be converted to rotations per second (RPS). As there are 60 seconds in a minute, all we have to do is to divide the RPM by 60 to convert it to RPS.
For example, if the armature is spinning at a rate of 1800 RPM on a two-pole alternator, we can say that it is spinning at 30 rotations per second. If this alternator has two poles, then in one second it will generate 30 cycles of voltage. It then could be said to have a frequency of 30 cycles per second or 30 Hertz. The frequency of an alternator is directly proportional to the rotational speed of the alternator.
Number of Poles
If we add poles to the alternator, we can change the frequency. In a two-pole alternator, Side A of the armature (Figure 53) passes from north to south, and then south to north, to create one complete sine wave. I f we add two more poles, as in Figure 54, then Side A of the armature will move past two north poles and two south poles in one full mechanical revolution.
Figure 53. Two pole alternator
Two full sine waves are created in one complete mechanical revolution. If a two-pole alternator creates one cycle of voltage in one second (or one hertz of frequency), a four pole alternator will create two cycles of voltage in one second (or two hertz).
The frequency of an alternator is directly proportional to the number of poles in the alternator.
Figure 54. Four pole alternator
Formula time!
Knowing that rotation speed is directly proportional to frequency and that the number of poles is directly proportional to frequency, we can use a formula. The formula looks like this:
$f= \dfrac{P}{2} \times \dfrac{N}{60} \tag{Frequency formula}$
where…
• $f$ = frequency in hertz
• $P$ = number of poles
• $N$ = rotational speed in RPM
We divide the number of poles by two because there will always be a set of two poles. You can’t have a north pole without a south. We divide the RPM by 60 because we are concerned with rotations per second, not rotations per minute. The formula in Figure 56 can be combined to look like this:
$f = \dfrac{PN}{120} \tag{Combined frequency formula}$
Video! This video will walk you through how frequency is related to the RPM and the number of poles of an alternator.
A YouTube element has been excluded from this version of the text. You can view it online here: https://pressbooks.bccampus.ca/trigf...ricians/?p=278 | textbooks/workforce/Electronics_Technology/Book%3A_Trigonometry_and_Single_Phase_AC_Generation_for_Electricians_(Flinn)/03%3A_AC_Generation/3.04%3A_AC_Waveform_Analysis.txt |
Nothing should be more important to you than your own safety.
Think about Charlie Morecraft.
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/motorcontrols/?p=25
He had an industrial accident that left him in the hospital for about five years. Think about that. A shortcut in safety procedures left him in the hospital for five. Long. Years.Charlie had to open a valve on a petroleum line. It was a routine task he’d done “a thousand times” before. It was messy and difficult. The valves leaked and were sticky, but management had planned to replace the valves, and they put a safe procedure in place to ensure the valves could be operated without danger to the operator. Spoiler alert: Charlie didn’t follow the procedure.
Charlie worked on the valve without his safety glasses, and the valve leaked. Charlie didn’t bother trying to control the petroleum leak (“this will just take a minute”), and it got worse. When Charlie completely actuated the valve, it sprayed material into his face and soaked his clothes. Now blinded, he ran past his truck toward a nearby safety shower. Unfortunately, Charlie left the truck running (against procedure), and it ignited the vapors, engulfing Charlie in a ball of fire. When you think about taking shortcuts at work, remember Charlie.
The work we do is dangerous, and while I can never watch Mehdi Sadaghar (an electrical engineer who does unsafe things with electricity) without laughing, we have to remember that electricity can be fatal, and you never want to be involved in an arc flash incident.
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/motorcontrols/?p=25
Shock Current Path
As we’ve already learned, electricity requires a complete path (circuit) to continuously flow. This is why the shock received from static electricity is only a momentary jolt: the flow of electrons is necessarily brief when static charges are equalized between two objects. Shocks of self-limited duration like this are rarely hazardous.
Without two contact points on the body for current to enter and exit, respectively, there is no hazard of shock. This is why birds can safely rest on high-voltage power lines without getting shocked: they make contact with the circuit at only one point.
In order for electrons to flow through a conductor, there must be a voltage present to motivate them. Voltage, as you should recall, is always relative between two points. There is no such thing as voltage “on” or “at” a single point in the circuit, and so the bird contacting a single point in the above circuit has no voltage applied across its body to establish a current through it. Yes, even though they rest on two feet, both feet are touching the same wire, making them electrically common. Electrically speaking, both of the bird’s feet touch the same point, hence there is no voltage between them to motivate current through the bird’s body.
This might lend one to believe that its impossible to be shocked by electricity by only touching a single wire. Like the birds, if we’re sure to touch only one wire at a time, we’ll be safe, right? Unfortunately, this is not correct. Unlike birds, people are usually standing on the ground when they contact a “live” wire. Many times, one side of a power system will be intentionally connected to earth ground, and so the person touching a single wire is actually making contact between two points in the circuit (the wire and earth ground):
The ground symbol is that set of three horizontal bars of decreasing width located at the lower-left of the circuit shown, and also at the foot of the person being shocked. In real life the power system ground consists of some kind of metallic conductor buried deep in the ground for making maximum contact with the earth. That conductor is electrically connected to an appropriate connection point on the circuit with thick wire. The victim’s ground connection is through their feet, which are touching the earth.
A few questions usually arise at this point in the mind of the student:
• If the presence of a ground point in the circuit provides an easy point of contact for someone to get shocked, why have it in the circuit at all? Wouldn’t a ground-less circuit be safer?
• The person getting shocked probably isn’t bare-footed. If rubber and fabric are insulating materials, then why aren’t their shoes protecting them by preventing a circuit from forming?
• How good of a conductor can dirt be? If you can get shocked by current through the earth, why not use the earth as a conductor in our power circuits?
In answer to the first question, the presence of an intentional “grounding” point in an electric circuit is intended to ensure that one side of it is safe to come in contact with. Note that if our victim in the above diagram were to touch the bottom side of the resistor, nothing would happen even though their feet would still be contacting ground:
Because the bottom side of the circuit is firmly connected to ground through the grounding point on the lower-left of the circuit, the lower conductor of the circuit is made electrically common with earth ground. Since there can be no voltage between electrically common points, there will be no voltage applied across the person contacting the lower wire, and they will not receive a shock. For the same reason, the wire connecting the circuit to the grounding rod/plates is usually left bare (no insulation), so that any metal object it brushes up against will similarly be electrically common with the earth.
Circuit grounding ensures that at least one point in the circuit will be safe to touch. But what about leaving a circuit completely ungrounded? Wouldn’t that make any person touching just a single wire as safe as the bird sitting on just one? Ideally, yes. Practically, no. Observe what happens with no ground at all:
Despite the fact that the person’s feet are still contacting ground, any single point in the circuit should be safe to touch. Since there is no complete path (circuit) formed through the person’s body from the bottom side of the voltage source to the top, there is no way for a current to be established through the person. However, this could all change with an accidental ground, such as a tree branch touching a power line and providing connection to earth ground:
Such an accidental connection between a power system conductor and the earth (ground) is called a ground fault. Ground faults may be caused by many things, including dirt buildup on power line insulators (creating a dirty-water path for current from the conductor to the pole, and to the ground, when it rains), ground water infiltration in buried power line conductors, and birds landing on power lines, bridging the line to the pole with their wings. Given the many causes of ground faults, they tend to be unpredictable. In the case of trees, no one can guarantee which wire their branches might touch. If a tree were to brush up against the top wire in the circuit, it would make the top wire safe to touch and the bottom one dangerous—just the opposite of the previous scenario where the tree contacts the bottom wire:
With a tree branch contacting the top wire, that wire becomes the grounded conductor in the circuit, electrically common with earth ground. Therefore, there is no voltage between that wire and ground, but full (high) voltage between the bottom wire and ground. As mentioned previously, tree branches are only one potential source of ground faults in a power system. Consider an ungrounded power system with no trees in contact, but this time with two people touching single wires:
With each person standing on the ground, contacting different points in the circuit, a path for shock current is made through one person, through the earth, and through the other person. Even though each person thinks they’re safe in only touching a single point in the circuit, their combined actions create a deadly scenario. In effect, one person acts as the ground fault which makes it unsafe for the other person. This is exactly why ungrounded power systems are dangerous: the voltage between any point in the circuit and ground (earth) is unpredictable, because a ground fault could appear at any point in the circuit at any time. The only character guaranteed to be safe in these scenarios is the bird, who has no connection to earth ground at all! By firmly connecting a designated point in the circuit to earth ground (“grounding” the circuit), at least safety can be assured at that one point. This is more assurance of safety than having no ground connection at all.
In answer to the second question, rubber-soled shoes do indeed provide some electrical insulation to help protect someone from conducting shock current through their feet. However, most common shoe designs are not intended to be electrically “safe,” their soles being too thin and not of the right substance. Also, any moisture, dirt, or conductive salts from body sweat on the surface of or permeated through the soles of shoes will compromise what little insulating value the shoe had to begin with. There are shoes specifically made for dangerous electrical work, as well as thick rubber mats made to stand on while working on live circuits, but these special pieces of gear must be in absolutely clean, dry condition in order to be effective. Suffice it to say, normal footwear is not enough to guarantee protection against electric shock from a power system.
Research conducted on contact resistance between parts of the human body and points of contact (such as the ground) shows a wide range of figures (see end of chapter for information on the source of this data):
• Hand or foot contact, insulated with rubber: 20 MΩ typical.
• Foot contact through leather shoe sole (dry): 100 kΩ to 500 kΩ
• Foot contact through leather shoe sole (wet): 5 kΩ to 20 kΩ
As you can see, not only is rubber a far better insulating material than leather, but the presence of water in a porous substance such as leather greatly reduces electrical resistance.
In answer to the third question, dirt is not a very good conductor (at least not when its dry!). It is too poor of a conductor to support continuous current for powering a load. However, as we will see in the next section, it takes very little current to injure or kill a human being, so even the poor conductivity of dirt is enough to provide a path for deadly current when there is sufficient voltage available, as there usually is in power systems.
Some ground surfaces are better insulators than others. Asphalt, for instance, being oil-based, has a much greater resistance than most forms of dirt or rock. Concrete, on the other hand, tends to have fairly low resistance due to its intrinsic water and electrolyte (conductive chemical) content.
Safe Practices
If at all possible, shut off the power to a circuit before performing any work on it. You must secure all sources of harmful energy before a system may be considered safe to work on. In industry, securing a circuit, device, or system in this condition is commonly known as placing it in a Zero Energy State. The focus of this lesson is, of course, electrical safety. However, many of these principles apply to non-electrical systems as well.
Securing something in a Zero Energy State means ridding it of any sort of potential or stored energy, including but not limited to:
• Dangerous voltage
• Spring pressure
• Hydraulic (liquid) pressure
• Pneumatic (air) pressure
• Suspended weight
• Chemical energy (flammable or otherwise reactive substances)
• Nuclear energy (radioactive or fissile substances)
Voltage by its very nature is a manifestation of potential energy. In the first chapter I even used elevated liquid as an analogy for the potential energy of voltage, having the capacity (potential) to produce current (flow), but not necessarily realizing that potential until a suitable path for flow has been established, and resistance to flow is overcome. A pair of wires with high voltage between them do not look or sound dangerous even though they harbor enough potential energy between them to push deadly amounts of current through your body. Even though that voltage isn’t presently doing anything, it has the potential to, and that potential must be neutralized before it is safe to physically contact those wires.
All properly designed circuits have “disconnect” switch mechanisms for securing voltage from a circuit. Sometimes these “disconnects” serve a dual purpose of automatically opening under excessive current conditions, in which case we call them “circuit breakers.” Other times, the disconnecting switches are strictly manually-operated devices with no automatic function. In either case, they are there for your protection and must be used properly. Please note that the disconnect device should be separate from the regular switch used to turn the device on and off. It is a safety switch, to be used only for securing the system in a Zero Energy State:
With the disconnect switch in the “open” position as shown (no continuity), the circuit is broken and no current will exist. There will be zero voltage across the load, and the full voltage of the source will be dropped across the open contacts of the disconnect switch. Note how there is no need for a disconnect switch in the lower conductor of the circuit. Because that side of the circuit is firmly connected to the earth (ground), it is electrically common with the earth and is best left that way. For maximum safety of personnel working on the load of this circuit, a temporary ground connection could be established on the top side of the load, to ensure that no voltage could ever be dropped across the load:
With the temporary ground connection in place, both sides of the load wiring are connected to ground, securing a Zero Energy State at the load.
Since a ground connection made on both sides of the load is electrically equivalent to short-circuiting across the load with a wire, that is another way of accomplishing the same goal of maximum safety:
Either way, both sides of the load will be electrically common to the earth, allowing for no voltage (potential energy) between either side of the load and the ground people stand on. This technique of temporarily grounding conductors in a de-energized power system is very common in maintenance work performed on high voltage power distribution systems.
A further benefit of this precaution is protection against the possibility of the disconnect switch being closed (turned “on” so that circuit continuity is established) while people are still contacting the load. The temporary wire connected across the load would create a short-circuit when the disconnect switch was closed, immediately tripping any overcurrent protection devices (circuit breakers or fuses) in the circuit, which would shut the power off again. Damage may very well be sustained by the disconnect switch if this were to happen, but the workers at the load are kept safe.
It would be good to mention at this point that overcurrent devices are not intended to provide protection against electric shock. Rather, they exist solely to protect conductors from overheating due to excessive currents. The temporary shorting wires just described would indeed cause any overcurrent devices in the circuit to “trip” if the disconnect switch were to be closed, but realize that electric shock protection is not the intended function of those devices. Their primary function would merely be leveraged for the purpose of worker protection with the shorting wire in place.
Since it is obviously important to be able to secure any disconnecting devices in the open (off) position and make sure they stay that way while work is being done on the circuit, there is need for a structured safety system to be put into place. Such a system is commonly used in industry and it is called Lock-out/Tag-out.
A lock-out/tag-out procedure works like this: all individuals working on a secured circuit have their own personal padlock or combination lock which they set on the control lever of a disconnect device prior to working on the system. Additionally, they must fill out and sign a tag which they hang from their lock describing the nature and duration of the work they intend to perform on the system. If there are multiple sources of energy to be “locked out” (multiple disconnects, both electrical and mechanical energy sources to be secured, etc.), the worker must use as many of his or her locks as necessary to secure power from the system before work begins. This way, the system is maintained in a Zero Energy State until every last lock is removed from all the disconnect and shutoff devices, and that means every last worker gives consent by removing their own personal locks. If the decision is made to re-energize the system and one person’s lock(s) still remain in place after everyone present removes theirs, the tag(s) will show who that person is and what it is they’re doing.
Even with a good lock-out/tag-out safety program in place, there is still need for diligence and common-sense precaution. This is especially true in industrial settings where a multitude of people may be working on a device or system at once. Some of those people might not know about proper lock-out/tag-out procedure, or might know about it but are too complacent to follow it. Don’t assume that everyone has followed the safety rules!
After an electrical system has been locked out and tagged with your own personal lock, you must then double-check to see if the voltage really has been secured in a zero state. One way to check is to see if the machine (or whatever it is that’s being worked on) will start up if the Start switch or button is actuated. If it starts, then you know you haven’t successfully secured the electrical power from it.
Additionally, you should always check for the presence of dangerous voltage with a measuring device before actually touching any conductors in the circuit. To be safest, you should follow this procedure of checking, using, and then checking your meter:
• Check to see that your meter indicates properly on a known source of voltage.
• Use your meter to test the locked-out circuit for any dangerous voltage.
• Check your meter once more on a known source of voltage to see that it still indicates as it should.
While this may seem excessive or even paranoid, it is a proven technique for preventing electrical shock. I once had a meter fail to indicate voltage when it should have while checking a circuit to see if it was “dead.” Had I not used other means to check for the presence of voltage, I might not be alive today to write this. There’s always the chance that your voltage meter will be defective just when you need it to check for a dangerous condition. Following these steps will help ensure that you’re never misled into a deadly situation by a broken meter.
Finally, the electrical worker will arrive at a point in the safety check procedure where it is deemed safe to actually touch the conductor(s). Bear in mind that after all of the precautionary steps have taken, it is still possible (although very unlikely) that a dangerous voltage may be present. One final precautionary measure to take at this point is to make momentary contact with the conductor(s) with the back of the hand before grasping it or a metal tool in contact with it. Why? If, for some reason there is still voltage present between that conductor and earth ground, finger motion from the shock reaction (clenching into a fist) will break contact with the conductor. Please note that this is absolutely the last step that any electrical worker should ever take before beginning work on a power system, and should never be used as an alternative method of checking for dangerous voltage. If you ever have reason to doubt the trustworthiness of your meter, use another meter to obtain a “second opinion.”
This chapter is an adaptation of Lessons in Electric Circuits by Tony R. Kuphaldt (on allaboutcircuits.com), and is used under a Design Science License. | textbooks/workforce/Electronics_Technology/Book%3A_Troubleshooting_Motors_and_Controls_(Dickson-Self)/01%3A_Lesson_1/1.01%3A_Safety.txt |
Hopefully by the time you’re considering wiring up motors and their controls, you already have a knowledge of electricity and how it behaves. The following is just a brief refresher, but any technician considering the wiring of three-phase motors should have a solid understanding of electrical fundamentals. If you do not have this understanding, please use your favorite education resource to complete training.
Electrons moving around in a never-ended loop is considered a circuit. Circuits that are closed allow for electron flow. Circuits that are open (broken) do not allow for electron flow.
Electricity has three main components. Voltage is the amount of potential electrical energy between two points, and it is usually represented by the letter E (for electromotive force) and is measured in volts, abbreviated with V. Current is the flow of electrons from negatively-charge atoms toward atoms with a positive charge. We measure current in Amperes or Amps (abbreviated A), and the symbol for current is I. Current that travels in only one direction we call direct current (DC). Current that changes direction at regular intervals we call alternating current (AC). The final component is resistance. Resistance (abbreviated R) is the opposition to current flow, and it is measured in ohms (abbreviated with the Greek letter Omega, Ω).
These three terms are related to one another in the following way: E = I * R. Knowing this, if we ever know any two of these variables in a circuit, we can always calculate the third. Two other ways to express the same equation are: I = E / R and R = E / I.
In electricity, we often use scientific notation and prefixes with the units we measure. If you’re unfamiliar with these concepts, you may want to study them a bit more. With electricity, some multiples and prefixes are used more often than others. These are in bold in the table below.
Abbreviations and Prefixes
When building electrical circuits, components can be connected in two basic ways: either in series with one another or in parallel.
Series
When there is only one path for current flow, the components are said to be in series. Look at this example of a series circuit.
Series circuit with three resistors
The circuit has three resistors (labeled R1, R2, and R3), and these resistors are in series with each other. Notice too that the push button (labeled PB) is also in series with the resistors, as is the 9-volt battery. There is only one path for electrons to take, and all electrons must follow the same path through the circuit when the push button is pushed.
Because the electrons only have one path, the current flow is the same throughout the entire circuit, and all resistances are cumulative. Let’s say that R1 has a resistance of 10Ω, R2 has a resistance of 20Ω, and R3 has a resistance of 30Ω. Because all resistances are cumulative and current is the same through, voltage at any particular component is determined by that component’s resistance. The formula look like this:
Series
RTotal = R1 + R2 + R3 + …
ITotal = I1 = I2 = I3 = …
ETotal = ER1 + ER2 + ER3 + …
In our example, total resistance is 60 ohms (10Ω + 20Ω + 30Ω). Since the total resistance is 60Ω in a 12-volt system, the total current must be 0.2A, or 200mA (12V/60Ω). Now that total current is known, voltage at each load can be calculated. For instance, the voltage at R1 (E=IR) is going to be 0.2A * 10Ω, or 2V. Voltage at R2 is 4V and voltage at R3 is 6V. Notice that all of our voltages (2V, 4V, 6V) add up to the source voltage of 12V. This rule applies to all series circuits.
Parallel
In parallel circuits, current flow has more than one path. This changes the behavior of the electrons in the circuit. First, the voltage across parallel components is no longer split among them. Since they are in parallel with one another (electrically common), they each get full voltage. Notice on the diagram below where the black connecting dots are located. Each of those represent two (or more) locations where voltage is going to be available equally in either direction.
Parallel Circuit with Three resistors
So, in this example, when the push button is pushed, 12 volts becomes available to every resistor in the circuit, since they are each parallel with each other (the push button, however, is still in series with all resistors). So, if every resistor has the full source voltage available, how much current will be flowing through the circuit? This depends on the resistance of each “branch” or “rung” of our circuit. We simply calculate the current through each resistor, then add them together to get the total current (see below).
Parallel
ETotal = E R1 = E R2 = E R3 = …
I Total = I 1 + I 2 + I 3 + …
RTotal = 1 / (1/R1 + 1/R2 + 1/R3 + …]
Total resistance, however, is now a little more difficult, because as resistors are added in parallel to our circuit, we’re providing more paths for electrons to flow. Each new path that’s added decreases the total resistance of the whole circuit. In fact, the total resistance of our parallel circuit MUST be lower than the resistance of the lowest resistor.
Let’s use the same resistance values as the series circuit (R1 has a resistance of 10Ω, R2 is 20Ω, and R3 is 30Ω). Knowing that our total resistance is now going to be less than 10Ω, let’s do the math.
RTotal = 1 / (1/10 + 1/20 + 1/30)
RTotal = 1 / (0.1 + 0.05 + 0.0333)
RTotal = 1 / 0.1833
RTotal = 5.45Ω
Clever technicians always look for ways to verify results. In this case, we could calculate current for our circuit at each resistor.
IR1 = 12/10 IR2 = 12/20 IR3 = 12/30
IR1 = 1.2A IR2 = 0.6A IR3 = 0.4A
ITotal = 1.2A + 0.6A + 0.4A = 2.2A of total current
Using Ohm’s Law, our total resistance should be equal to total voltage divided by total current, and indeed, if we divide 12V by 2.2A, we get a total resistance of 5.45Ω. matching our previous result. Nice.
Testing Components
Switches/Contacts
Switches and contacts are designed to allow and stop the flow of current. When a switch or set of contacts are closed, the resistance should be very low (near zero), meaning that very little voltage is dropped (near zero). When a switch or set of contacts are open, the resistance should be infinite (OL on many meters), meaning that all potential voltage is available across those open contacts (assuming there aren’t other opens in series with the one being measured).
Protection Devices
Testing fuses, circuit breakers, or overloads is similar to testing switches, except they are designed to always allow current flow. It’s only when a protection device has experienced current higher than its specified amount that the device opens the circuit, stopping current. When testing resistance, these devices should have very low resistance. Since they are placed in series with the circuit they are designed to protect, we don’t want them using up available voltage. A protection device with infinite resistance is “blown” or in its “tripped” state. When measuring voltage across one of these devices, when good there should be very little voltage dropped. If source voltage is present, the device is “blown” or in its “tripped” state.
Loads
Loads are designed to use applied voltage to do the work of the circuit. This could be running a motor, lighting a bulb, or actuating a relay. Loads need to have some amount of resistance (this amount will vary by load and can be found by checking the manufacturer’s specifications or measuring similar “known good” parts). Loads that measure either no resistance or an infinite amount of resistance are not good. Because loads are designed to use the available voltage, measuring voltage at a load may not always tell you if the load is good or bad. If the load has an internal open, source voltage will be read at the load. If the load is working properly, source voltage will also be found at the load. If the load is shorted, most likely, any protection devices in the circuit (fuses, circuit breakers, overloads) will be tripped, due to the increased current.
Relays
Because relays operate like an electrically-controlled switch, you have two components to test. First is the coil of the relay, which acts as a load. Next are the contacts within the relay, which act as switches. The contacts of the relay are often in a different circuit than the coil, but all of these components are tested as described above.
Transformers
Lastly are transformers. Transformers are typically used to change AC voltage by either stepping it up or stepping it down. Transformers consist of two coils of wire wrapped around an iron core. The coils of wire behave like a typical load and can be tested similarly, as described above.
Step-down Transformer
1. Test primary coil
2. Test secondary coil
3. Measure Resistance (Rs) from primary to secondary coil (should be no continuity)
4. Measure Rs from Primary coil to transformer housing (should be no continuity)
5. Measure Rs from Secondary coil to transformer housing (should be no continuity)
Ladder Diagrams
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/motorcontrols/?p=44 | textbooks/workforce/Electronics_Technology/Book%3A_Troubleshooting_Motors_and_Controls_(Dickson-Self)/01%3A_Lesson_1/1.02%3A_Electrical_Fundamentals.txt |
Safe Meter Usage
Using an electrical meter safely and efficiently is perhaps the most valuable skill an electronics technician can master, both for the sake of their own personal safety and for proficiency at their trade. It can be daunting at first to use a meter, knowing that you are connecting it to live circuits which may harbor life-threatening levels of voltage and current. This concern is not unfounded, and it is always best to proceed cautiously when using meters. Carelessness more than any other factor is what causes experienced technicians to have electrical accidents.
The most common piece of electrical test equipment is a meter called the multimeter. Multimeters are so named because they have the ability to measure a multiple of variables: voltage, current, resistance, and often many others, some of which cannot be explained here due to their complexity. In the hands of a trained technician, the multimeter is both an efficient work tool and a safety device. In the hands of someone ignorant and/or careless, however, the multimeter may become a source of danger when connected to a “live” circuit.
There are many different brands of multimeters, with multiple models made by each manufacturer sporting different sets of features. Most meters used in industry today have digital displays, rather than a needle style. These Digital Multimeters (DMMs) allow us to measure voltage, current and resistance. The multimeter shown here in the following illustrations is a “generic” design, not specific to any manufacturer, but general enough to teach the basic principles of use:
The rotary selector switch (now set in the Off position) has five different measurement positions it can be set in: two “V” settings, two “A” settings, and one setting in the middle with a funny-looking “horseshoe” symbol on it representing “resistance.” The “horseshoe” symbol is the Greek letter “Omega” (Ω), which is the common symbol for the electrical unit of ohms.
Of the two “V” settings and two “A” settings, you will notice that each pair is divided into unique markers with either a pair of horizontal lines (one solid, one dashed), or a dashed line with a squiggly curve over it. The parallel lines represent “DC” while the squiggly curve represents “AC.” The “V” of course stands for “voltage” while the “A” stands for “amperage” (current). The meter uses different techniques, internally, to measure DC than it uses to measure AC, and so it requires the user to select which type of voltage (V) or current (A) is to be measured. Although we haven’t discussed alternating current (AC) in any technical detail, this distinction in meter settings is an important one to bear in mind.
There are three different sockets on the multimeter face into which we can plug our test leads. Test leads are nothing more than specially-prepared wires used to connect the meter to the circuit under test. The wires are coated in a color-coded (either black or red) flexible insulation to prevent the user’s hands from contacting the bare conductors, and the tips of the probes are sharp, stiff pieces of wire:
The black test lead always plugs into the black socket on the multimeter: the one marked “COM” for “common.” The red test lead plugs into either the red socket marked for voltage and resistance, or the red socket marked for current, depending on which quantity you intend to measure with the multimeter.
To see how this works, let’s look at a couple of examples showing the meter in use. First, we’ll set up the meter to measure DC voltage from a battery:
Note that the two test leads are plugged into the appropriate sockets on the meter for voltage, and the selector switch has been set for DC “V”. Now, we’ll take a look at an example of using the multimeter to measure AC voltage from a household electrical power receptacle (wall socket):
The only difference in the setup of the meter is the placement of the selector switch: it is now turned to AC “V”. Since we’re still measuring voltage, the test leads will remain plugged in the same sockets. In both of these examples, it is imperative that you not let the probe tips come in contact with one another while they are both in contact with their respective points on the circuit. If this happens, a short-circuit will be formed, creating a spark and perhaps even a ball of flame if the voltage source is capable of supplying enough current! The following image illustrates the potential for hazard:
This is just one of the ways that a meter can become a source of hazard if used improperly.
Voltage measurement is perhaps the most common function a multimeter is used for. It is certainly the primary measurement taken for safety purposes (part of the lock-out/tag-out procedure), and it should be well understood by the operator of the meter. Being that voltage is always relative between two points, the meter must be firmly connected to two points in a circuit before it will provide a reliable measurement. That usually means both probes must be grasped by the user’s hands and held against the proper contact points of a voltage source or circuit while measuring.
Because a hand-to-hand shock current path is the most dangerous, holding the meter probes on two points in a high-voltage circuit in this manner is always a potential hazard. If the protective insulation on the probes is worn or cracked, it is possible for the user’s fingers to come into contact with the probe conductors during the time of test, causing a bad shock to occur. If it is possible to use only one hand to grasp the probes, that is a safer option. Sometimes it is possible to “latch” one probe tip onto the circuit test point so that it can be let go of and the other probe set in place, using only one hand. Special probe tip accessories such as spring clips can be attached to help facilitate this.
Remember that meter test leads are part of the whole equipment package, and that they should be treated with the same care and respect that the meter itself is. If you need a special accessory for your test leads, such as a spring clip or other special probe tip, consult the product catalog of the meter manufacturer or other test equipment manufacturer. Do not try to be creative and make your own test probes, as you may end up placing yourself in danger the next time you use them on a live circuit.
Also, it must be remembered that digital multimeters usually do a good job of discriminating between AC and DC measurements, as they are set for one or the other when checking for voltage or current. As we have seen earlier, both AC and DC voltages and currents can be deadly, so when using a multimeter as a safety check device you should always check for the presence of both AC and DC, even if you’re not expecting to find both! Also, when checking for the presence of hazardous voltage, you should be sure to check all pairs of points in question.
For example, suppose that you opened up an electrical wiring cabinet to find three large conductors supplying AC power to a load. The circuit breaker feeding these wires (supposedly) has been shut off, locked, and tagged. You double-checked the absence of power by pressing the Startbutton for the load. Nothing happened, so now you move on to the third phase of your safety check: the meter test for voltage.
First, you check your meter on a known source of voltage to see that its working properly. Any nearby power receptacle should provide a convenient source of AC voltage for a test. You do so and find that the meter indicates as it should. Next, you need to check for voltage among these three wires in the cabinet. But voltage is measured between two points, so where do you check?
The answer is to check between all combinations of those three points. As you can see, the points are labeled “A”, “B”, and “C” in the illustration, so you would need to take your multimeter (set in the voltmeter mode) and check between points A & B, B & C, and A & C. If you find voltage between any of those pairs, the circuit is not in a Zero Energy State. But wait! Remember that a multimeter will not register DC voltage when its in the AC voltage mode and vice versa, so you need to check those three pairs of points in each mode for a total of six voltage checks in order to be complete!
However, even with all that checking, we still haven’t covered all possibilities yet. Remember that hazardous voltage can appear between a single wire and ground (in this case, the metal frame of the cabinet would be a good ground reference point) in a power system. So, to be perfectly safe, we not only have to check between A & B, B & C, and A & C (in both AC and DC modes), but we also have to check between A & ground, B & ground, and C & ground (in both AC and DC modes)! This makes for a grand total of twelve voltage checks for this seemingly simple scenario of only three wires. Then, of course, after we’ve completed all these checks, we need to take our multimeter and re-test it against a known source of voltage such as a power receptacle to ensure that its still in good working order.
Using a multimeter to check for resistance is a much simpler task. The test leads will be kept plugged in the same sockets as for the voltage checks, but the selector switch will need to be turned until it points to the “horseshoe” resistance symbol. Touching the probes across the device whose resistance is to be measured, the meter should properly display the resistance in ohms:
One very important thing to remember about measuring resistance is that it must only be done on de-energized components! When the meter is in “resistance” mode, it uses a small internal battery to generate a tiny current through the component to be measured. By sensing how difficult it is to move this current through the component, the resistance of that component can be determined and displayed. If there is any additional source of voltage in the meter-lead-component-lead-meter loop to either aid or oppose the resistance-measuring current produced by the meter, faulty readings will result. In a worse-case situation, the meter may even be damaged by the external voltage.
The “resistance” mode of a multimeter is very useful in determining wire continuity as well as making precise measurements of resistance. When there is a good, solid connection between the probe tips (simulated by touching them together), the meter shows almost zero Ω. If the test leads had no resistance in them, it would read exactly zero:
If the leads are not in contact with each other, or touching opposite ends of a broken wire, the meter will indicate infinite resistance (usually by displaying dashed lines or the abbreviation “O.L.” which stands for “open loop”):
By far the most hazardous and complex application of the multimeter is in the measurement of current. The reason for this is quite simple: in order for the meter to measure current, the current to be measured must be forced to go through the meter. This means that the meter must be made part of the current path of the circuit rather than just be connected off to the side somewhere as is the case when measuring voltage. In order to make the meter part of the current path of the circuit, the original circuit must be “broken” and the meter connected across the two points of the open break. To set the meter up for this, the selector switch must point to either AC or DC “A” and the red test lead must be plugged in the red socket marked “A”. The following illustration shows a meter all ready to measure current and a circuit to be tested:
Now, the circuit is broken in preparation for the meter to be connected:
The next step is to insert the meter in-line with the circuit by connecting the two probe tips to the broken ends of the circuit, the black probe to the negative (-) terminal of the 9-volt battery and the red probe to the loose wire end leading to the lamp:
This example shows a very safe circuit to work with. 9 volts hardly constitutes a shock hazard, and so there is little to fear in breaking this circuit open (bare handed, no less!) and connecting the meter in-line with the flow of electrons. However, with higher power circuits, this could be a hazardous endeavor indeed. Even if the circuit voltage was low, the normal current could be high enough that an injurious spark would result the moment the last meter probe connection was established.
Another potential hazard of using a multimeter in its current-measuring (“ammeter”) mode is failure to properly put it back into a voltage-measuring configuration before measuring voltage with it. The reasons for this are specific to ammeter design and operation. When measuring circuit current by placing the meter directly in the path of current, it is best to have the meter offer little or no resistance against the flow of electrons. Otherwise, any additional resistance offered by the meter would impede the electron flow and alter the circuits operation. Thus, the multimeter is designed to have practically zero ohms of resistance between the test probe tips when the red probe has been plugged into the red “A” (current-measuring) socket. In the voltage-measuring mode (red lead plugged into the red “V” socket), there are many mega-ohms of resistance between the test probe tips, because voltmeters are designed to have close to infinite resistance (so that they don’t draw any appreciable current from the circuit under test).
When switching a multimeter from current- to voltage-measuring mode, its easy to spin the selector switch from the “A” to the “V” position and forget to correspondingly switch the position of the red test lead plug from “A” to “V”. The result—if the meter is then connected across a source of substantial voltage—will be a short-circuit through the meter!
To help prevent this, most multimeters have a warning feature by which they beep if ever there’s a lead plugged in the “A” socket and the selector switch is set to “V”. As convenient as features like these are, though, they are still no substitute for clear thinking and caution when using a multimeter.
All good-quality multimeters contain fuses inside that are engineered to “blow” in the event of excessive current through them, such as in the case illustrated in the last image. Like all overcurrent protection devices, these fuses are primarily designed to protect the equipment (in this case, the meter itself) from excessive damage, and only secondarily to protect the user from harm. A multimeter can be used to check its own current fuse by setting the selector switch to the resistance position and creating a connection between the two red sockets like this:
A good fuse will indicate very little resistance while a blown fuse will always show “O.L.” (or whatever indication that model of multimeter uses to indicate no continuity). The actual number of ohms displayed for a good fuse is of little consequence, so long as its an arbitrarily low figure.
So now that we’ve seen how to use a multimeter to measure voltage, resistance, and current, what more is there to know? Plenty! The value and capabilities of this versatile test instrument will become more evident as you gain skill and familiarity using it. There is no substitute for regular practice with complex instruments such as these, so feel free to experiment on safe, battery-powered circuits.
This chapter is an adaptation of Lessons in Electric Circuits by Tony R. Kuphaldt (on allaboutcircuits.com), and is used under a Design Science License.
1.04: Homework 1
Use the following schematic for questions 1, 2 and 3.
1. Between which points would you expect to measure no voltage?
2. Between which points would you expect to measure source voltage?
3. The light bulb stops working. Using your meter, you read zero volts between points F and H and between E and J. You measure source voltage from I and B and from G and J. Where is the problem located?
4. Draw a ladder diagram of the following circuit:
Wired Circuit
5. Using Ohm’s Law, fill in the missing values for the following circuit:
Series Circuit
R1 R2 R3 Total
E 12V
I
R 3Ω 6Ω 4Ω
6. Using Ohm’s Law, fill in the missing values for the following circuit:
Parallel circuit
R1 R2 R3 Total
E 12V
I
R 3Ω 6Ω 4Ω
7. Given the following schematic diagram with a control relay, siren and four switches, describe the behavior of this circuit in words.
Speaker Circuit
8. How much current is in a 12V circuit that has 24kΩ of resistance?
9. How much voltage is present in a circuit with 30mA of current and 800Ω of resistance?
10. What resistance is present in a circuit with 120V and 80µA of current?
11. How would you write 2.4MΩ in scientific notation?
12. How would you write 2.4µA in scientific notation?
13. How might you write 3.45 x 108A?
14. How might you write 8.34 x 10-6Ω?
15. In the circuit below, draw in your meter to measure the following properties:
1. Resistance of R1
2. Voltage across R2
3. Current through R1, R2, and R3 | textbooks/workforce/Electronics_Technology/Book%3A_Troubleshooting_Motors_and_Controls_(Dickson-Self)/01%3A_Lesson_1/1.03%3A_Meter_Usage.txt |
With simple series circuits, all components are connected end-to-end to form only one path for electrons to flow through the circuit:
With simple parallel circuits, all components are connected between the same two sets of electrically common points, creating multiple paths for electrons to flow from one end of the battery to the other:
With each of these two basic circuit configurations, we have specific sets of rules describing voltage, current, and resistance relationships.
• Series Circuits:
• Voltage drops add to equal total voltage.
• All components share the same (equal) current.
• Resistances add to equal total resistance.
• Parallel Circuits:
• All components share the same (equal) voltage.
• Branch currents add to equal total current.
• Resistances diminish to equal total resistance.
However, if circuit components are series-connected in some parts and parallel in others, we won’t be able to apply a single set of rules to every part of that circuit. Instead, we will have to identify which parts of that circuit are series and which parts are parallel, then selectively apply series and parallel rules as necessary to determine what is happening. Take the following circuit, for instance:
This circuit is neither simple series nor simple parallel. Rather, it contains elements of both. The current exits the bottom of the battery, splits up to travel through R3 and R4, rejoins, then splits up again to travel through R1and R2, then rejoins again to return to the top of the battery. There exists more than one path for current to travel (not series), yet there are more than two sets of electrically common points in the circuit (not parallel).
Because the circuit is a combination of both series and parallel, we cannot apply the rules for voltage, current, and resistance “across the table” to begin analysis like we could when the circuits were one way or the other. For instance, if the above circuit were simple series, we could just add up R1 through R4 to arrive at a total resistance, solve for total current, and then solve for all voltage drops. Likewise, if the above circuit were simple parallel, we could just solve for branch currents, add up branch currents to figure the total current, and then calculate total resistance from total voltage and total current. However, this circuit’s solution will be more complex.
The table will still help us manage the different values for series-parallel combination circuits, but we’ll have to be careful how and where we apply the different rules for series and parallel. Ohm’s Law, of course, still works just the same for determining values within a vertical column in the table.
If we are able to identify which parts of the circuit are series and which parts are parallel, we can analyze it in stages, approaching each part one at a time, using the appropriate rules to determine the relationships of voltage, current, and resistance. The rest of this chapter will be devoted to showing you techniques for doing this.
Process of Series-Parallel Resistor Circuit Analysis
The goal of series-parallel resistor circuit analysis is to be able to determine all voltage drops, currents, and power dissipations in a circuit. The general strategy to accomplish this goal is as follows:
• Step 1: Assess which resistors in a circuit are connected together in simple series or simple parallel.
• Step 2: Re-draw the circuit, replacing each of those series or parallel resistor combinations identified in step 1 with a single, equivalent-value resistor. If using a table to manage variables, make a new table column for each resistance equivalent.
• Step 3: Repeat steps 1 and 2 until the entire circuit is reduced to one equivalent resistor.
• Step 4: Calculate total current from total voltage and total resistance (I=E/R).
• Step 5: Taking total voltage and total current values, go back to last step in the circuit reduction process and insert those values where applicable.
• Step 6: From known resistances and total voltage / total current values from step 5, use Ohm’s Law to calculate unknown values (voltage or current) (E=IR or I=E/R).
• Step 7: Repeat steps 5 and 6 until all values for voltage and current are known in the original circuit configuration. Essentially, you will proceed step-by-step from the simplified version of the circuit back into its original, complex form, plugging in values of voltage and current where appropriate until all values of voltage and current are known.
• Step 8: Calculate power dissipations from known voltage, current, and/or resistance values.
This may sound like an intimidating process, but its much easier understood through example than through description.
In the example circuit above, R1 and R2 are connected in a simple parallel arrangement, as are R3 and R4. Having been identified, these sections need to be converted into equivalent single resistors, and the circuit re-drawn:
The double slash (//) symbols represent “parallel” to show that the equivalent resistor values were calculated using the 1/(1/R) formula. The 71.429 Ω resistor at the top of the circuit is the equivalent of R1 and R2 in parallel with each other. The 127.27 Ω resistor at the bottom is the equivalent of R3 and R4 in parallel with each other.
It should be apparent now that the circuit has been reduced to a simple series configuration with only two (equivalent) resistances. The final step in reduction is to add these two resistances to come up with a total circuit resistance. When we add those two equivalent resistances, we get a resistance of 198.70 Ω. Now, we can re-draw the circuit as a single equivalent resistance and add the total resistance figure to the rightmost column of our table. Note that the “Total” column has been relabeled (R1//R2—R3//R4) to indicate how it relates electrically to the other columns of figures. The “—” symbol is used here to represent “series,” just as the “//” symbol is used to represent “parallel.”
Now, total circuit current can be determined by applying Ohm’s Law (I=E/R) to the “Total” column in the table:
Back to our equivalent circuit drawing, our total current value of 120.78 milliamps is shown as the only current here:
Now we start to work backwards in our progression of circuit re-drawings to the original configuration. The next step is to go to the circuit where R1//R2and R3//R4 are in series:
Since R1//R2 and R3//R4 are in series with each other, the current through those two sets of equivalent resistances must be the same. Furthermore, the current through them must be the same as the total current, so we can fill in our table with the appropriate current values, simply copying the current figure from the Total column to the R1//R2 and R3//R4 columns:
Now, knowing the current through the equivalent resistors R1//R2 and R3//R4, we can apply Ohm’s Law (E=IR) to the two right vertical columns to find voltage drops across them:
Because we know R1//R2 and R3//R4 are parallel resistor equivalents, and we know that voltage drops in parallel circuits are the same, we can transfer the respective voltage drops to the appropriate columns on the table for those individual resistors. In other words, we take another step backwards in our drawing sequence to the original configuration, and complete the table accordingly:
Finally, the original section of the table (columns R1 through R4) is complete with enough values to finish. Applying Ohm’s Law to the remaining vertical columns (I=E/R), we can determine the currents through R1, R2, R3, and R4individually:
Placing Voltage and Current Values into Diagrams
Having found all voltage and current values for this circuit, we can show those values in the schematic diagram as such:
As a final check of our work, we can see if the calculated current values add up as they should to the total. Since R1 and R2 are in parallel, their combined currents should add up to the total of 120.78 mA. Likewise, since R3 and R4 are in parallel, their combined currents should also add up to the total of 120.78 mA. You can check for yourself to verify that these figures do add up as expected.
This chapter is an adaptation of Lessons in Electric Circuits by Tony R. Kuphaldt (on allaboutcircuits.com), and is used under a Design Science License. | textbooks/workforce/Electronics_Technology/Book%3A_Troubleshooting_Motors_and_Controls_(Dickson-Self)/02%3A_Lesson_2/2.01%3A_Combination_Series_and_Parallel_Circuits.txt |
Typically, complex circuits are not arranged in nice, neat, clean schematic diagrams for us to follow. They are often drawn in such a way that makes it difficult to follow which components are in series and which are in parallelwith each other. The purpose of this section is to show you a method useful for re-drawing circuit schematics in a neat and orderly fashion. Like the stage-reduction strategy for solving series-parallel combination circuits, it is a method easier demonstrated than described.
Let’s start with the following (convoluted) circuit diagram. Perhaps this diagram was originally drawn this way by a technician or engineer. Perhaps it was sketched as someone traced the wires and connections of a real circuit. In any case, here it is in all its ugliness:
With electric circuits and circuit diagrams, the length and routing of wire connecting components in a circuit matters little. (Actually, in some AC circuits it becomes critical, and very long wire lengths can contribute unwanted resistance to both AC and DC circuits, but in most cases wire length is irrelevant.) What this means for us is that we can lengthen, shrink, and/or bend connecting wires without affecting the operation of our circuit.
The strategy I have found easiest to apply is to start by tracing the current from one terminal of the battery around to the other terminal, following the loop of components closest to the battery and ignoring all other wires and components for the time being. While tracing the path of the loop, mark each resistor with the appropriate polarity for voltage drop.
In this case, I’ll begin my tracing of this circuit at the negative terminal of the battery and finish at the positive terminal, in the same general direction as the electrons would flow. When tracing this direction, I will mark each resistor with the polarity of negative on the entering side and positive on the exiting side, for that is how the actual polarity will be as electrons (negative in charge) enter and exit a resistor:
Any components encountered along this short loop are drawn vertically in order:
Now, proceed to trace any loops of components connected around components that were just traced. In this case, there’s a loop around R1formed by R2, and another loop around R3 formed by R4:
Tracing those loops, I draw R2 and R4 in parallel with R1 and R3(respectively) on the vertical diagram. Noting the polarity of voltage drops across R3 and R1, I mark R4 and R2 likewise:
Now we have a circuit that is very easily understood and analyzed. In this case, it is identical to the four-resistor series-parallel configuration we examined earlier in the chapter.
Let’s look at another example, even uglier than the one before:
The first loop I’ll trace is from the negative (-) side of the battery, through R6, through R1, and back to the positive (+) end of the battery:
Re-drawing vertically and keeping track of voltage drop polarities along the way, our equivalent circuit starts out looking like this:
Next, we can proceed to follow the next loop around one of the traced resistors (R6), in this case, the loop formed by R5 and R7. As before, we start at the negative end of R6 and proceed to the positive end of R6, marking voltage drop polarities across R7 and R5 as we go:
Now we add the R5—R7 loop to the vertical drawing. Notice how the voltage drop polarities across R7 and R5 correspond with that of R6, and how this is the same as what we found tracing R7 and R5 in the original circuit:
We repeat the process again, identifying and tracing another loop around an already-traced resistor. In this case, the R3—R4 loop around R5 looks like a good loop to trace next:
Adding the R3—R4 loop to the vertical drawing, marking the correct polarities as well:
With only one remaining resistor left to trace, then next step is obvious: trace the loop formed by R2 around R3:
Adding R2 to the vertical drawing, and we’re finished! The result is a diagram that’s very easy to understand compared to the original:
This simplified layout greatly eases the task of determining where to start and how to proceed in reducing the circuit down to a single equivalent (total) resistance. Notice how the circuit has been re-drawn, all we have to do is start from the right-hand side and work our way left, reducing simple-series and simple-parallel resistor combinations one group at a time until we’re done.
In this particular case, we would start with the simple parallel combination of R2 and R3, reducing it to a single resistance. Then, we would take that equivalent resistance (R2//R3) and the one in series with it (R4), reducing them to another equivalent resistance (R2//R3—R4). Next, we would proceed to calculate the parallel equivalent of that resistance (R2//R3—R4) with R5, then in series with R7, then in parallel with R6, then in series with R1 to give us a grand total resistance for the circuit as a whole.
From there we could calculate total current from total voltage and total resistance (I=E/R), then “expand” the circuit back into its original form one stage at a time, distributing the appropriate values of voltage and current to the resistances as we go.
This chapter is an adaptation of Lessons in Electric Circuits by Tony R. Kuphaldt (on allaboutcircuits.com), and is used under a Design Science License. | textbooks/workforce/Electronics_Technology/Book%3A_Troubleshooting_Motors_and_Controls_(Dickson-Self)/02%3A_Lesson_2/2.02%3A_Redrawing_Complex_Circuits.txt |
Logic in Electronics
While this lesson is a brief introduction to logic, understand that almost no part of our modern society can function without the touch of digital electronics. Everything from our TVs to phones, cars to gaming consoles, and computers to even the cash registers at the local grocery store would not be possible without these electronic devices. In this lesson, you’ll learn how to hard-wire these types of logical functions. Later, when you learn to use Programmable Logic Controllers (PLCs), you’ll also learn about the small electronic devices that perform the following functions.
AND
Logical AND
In words, the logical AND sounds something like this, “If A AND B are pressed, then Y is energized.”
Considering A and B as our inputs, we can determine when Y (our output) is energized. Folks sometimes use a truth table to help analyze these functions. We use binary (using only the numerals 0 and 1) to help represent the state of our circuit. Binary can be used any time something only has two states (true/false, high/low, yes/no, open/closed, etc.). If “0” is the normal state, and “1” denotes an activated or energized state, let’s look a truth table for the AND function.
AND
A B Y
0 0 0
0 1 0
1 0 0
1 1 1
The table is read row-by-row. In the first case, neither A or B is pressed, and Y is not activate. In the second row, A is not pressed, B is pressed, and Y is not energized. Notice that Y is only energized when both A and B are pressed. In any other case, lamp Y is not lit.
OR
Logical OR
In words, the logical OR description might be, “If button A OR B are pressed, then Y is energized.”
The truth table for OR logic looks like the following. Notice that in this case, the only time lamp Y is not lit is in the first row when neither button is pressed. In all other cases, Y is energized.
OR
A B Y
0 0 0
0 1 1
1 0 1
1 1 1
NOT
Logical NOT
Not is the simplest logical operation. It simply takes the input and inverts it. In our case, if button A is NOT pressed, then Y is energized (you could also say that if A is pressed, then Y is NOT energized). The truth table is shorter, since there’s only one input, and it looks like this:
OR
A Y
0 1
1 0
NOR
Logical NOR
In the case of NOR, Y is energized as long as neither A NOR B is pushed. Notice that the truth table is an exact inverse of OR. In the case of OR, Y was energized if either button was pressed. With NOR, Y is de-energized if either button is pushed.
NOR
A B Y
0 0 1
0 1 0
1 0 0
1 1 0
NAND
Logical NAND
With NAND, if both A and B are not pressed, then Y is energized. Notice the wording NOT AND. Looking at the truth table might confirm your suspicions. The output column for NAND is an inverse of the AND truth table.
NAND
A B Y
0 0 1
0 1 1
1 0 1
1 1 0
XOR
Logical XOR
XOR (pronounced “ex-or” or “exclusive or”) allows us to energize Y if either A or B is pressed, but not if both are pressed. So, it’s function is like OR logic, but the load is not energized if both buttons are pressed.
2.04: Homework 2
1. Calculate the resistance between points A and B for the following resistor networks:
2. From this circuit (with components attached to a “terminal strip”), draw an appropriate schematic diagram. Then explain the function of the resistor and what happens when the pushbutton is pressed (assuming it is normally open).
3. Complete the table of values for this circuit:
4. Draw a schematic for the following:
5. Considering your two inputs (A and B) in the image below, what type of logic is used to actuate the coil of CR3? Lamp 1? Lamp 2? If Lamp 2 never turns on, what components of the circuit could be causing the problem?
6. Create a truth table for the following diagram:What conditions must exist in order for the light to energize?
7. Create a simplified schematic for the following complex circuit:
8. Complete the table for the following schematic: Express all current in milliamps.
R1 R2 R3 R2 // R3 Total
E 48 V
I
R 120 Ω 120 Ω 200 Ω
9. Create a truth table for the following diagram: What conditions must exist in order for the light to energize?
This chapter is an adaptation of Lessons in Electric Circuits by Tony R. Kuphaldt (on allaboutcircuits.com), and is used under a Design Science License.
Media Attributions
• Logic Problem
• Complex Circuit
• Combination Circuit
• Logic Problem 2 | textbooks/workforce/Electronics_Technology/Book%3A_Troubleshooting_Motors_and_Controls_(Dickson-Self)/02%3A_Lesson_2/2.03%3A_Introduction_to_Logic.txt |
In order to understand how motors are controlled, it is first necessary to understand the basics.
To help with this, we’ll be using several videos from Jim Pytel’s Big Bad Tech YouTube channel. The playlist we’ll be using is titled Electrically Controlled Systems. There are over 50 videos in this playlist, and while we won’t be using all of them, you’d be well-served to watch as many of them as you can throughout the term. The information there is clear, concise, and entertaining. Much of the hardware described in labs for this course may not match the components used in the video, but this actually helps you to learn about the many varieties of hardware you’ll find in industry.
The following videos are REQUIRED for this lesson before starting Lab 3. Give yourself a couple hours to watch the videos and digest the material. Remember, this isn’t like that History of Architecture class you took in high school, wondering if you were ever going to use the information you were being tested on. If you’re taking this course, you’ve chosen a profession that requires you to know how to wire, maintain and repair systems very similar to this. Do not short-change yourself, thinking you’ll be able to skim material and still be an effective technician. You won’t. What you’ll become, if you’re ever hired into the field, is a liability to yourself, your company, and your co-workers. Taking time now will prevent potentially disastrous mistakes later.
Contactors
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/motorcontrols/?p=152
Control Relays
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/motorcontrols/?p=152
Overload Relays
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/motorcontrols/?p=152
2- and 3-Wire Magnetic Motor Starters
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/motorcontrols/?p=152
3.02: Homework 3
1. Create a truth table for each of the following circuits and identify the logical function of each (what’s it take for the pilot light to energize?).
2. You’ve been given a partial ladder diagram. Finish the diagram so that an OR function is formed (the indicator lamp energizes if either button A OR B is actuated).
3. Analyze this AC motor control circuit diagram, explaining the meaning of each symbol. Also, explain the operation of this motor control circuit. What happens when someone pushes the “Run” button? What happens when they let go of the “Run” button? When does the motor stop?
4. The L-side of the contactor is often known as the _______ side, while the T-side of the contactor is often known as the _______ side.
5. What do the auxiliary contacts of a contactor do?
6. Describe, in your own words, the difference between pick-up, hold-in, and dropout voltage.
7. According to the video, how much greater is inrush current than full load current?
8. Use IEC numbering to label the following two schematics (you can re-draw these on separate paper, if necessary):
9. List 5 possible causes of overload in an industrial setting.
10. What are the two components of a motor starter?
11. What’s the difference between a manual and automatic reset on an overload relay?
12. Name three types of overloads discussed in the video.
13. Draw the NEMA schematic symbol for an overload and show how overloads are represented in a ladder diagram.
14. Draw a diagram (not one used in the video) of a 2-wire circuit.
15. Draw a diagram (not one used in the video) of a 3-wire circuit.
This chapter is an adaptation of Lessons in Electric Circuits by Tony R. Kuphaldt (on allaboutcircuits.com), and is used under a Design Science License.
Media Attributions
• Relay Schematics | textbooks/workforce/Electronics_Technology/Book%3A_Troubleshooting_Motors_and_Controls_(Dickson-Self)/03%3A_Lesson_3/3.01%3A_Motor_Controls_-_Introduction.txt |
In this lesson, we’ll learn how to wire and draw multiple push buttons into our motor control station. It is often convenient to be able to control industrial machinery or equipment from more than one location. In this lesson, we’ll combine videos, schematics, and lab activities to deepen our understanding of the best way of adding multiple inputs to control motors.
Again, we’ll be using several videos from Jim Pytel’s Big Bad Tech YouTube channel.
The following videos are REQUIRED for this lesson before starting Lab 4. Remember to give yourself ample time to watch the videos and digest the material BEFORE coming in to do the labs.
HAND-OFF-AUTO Circuits
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/motorcontrols/?p=182
Troubleshooting HAND-OFF-AUTO Circuits
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/motorcontrols/?p=182
Multiple Push Button Stations
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/motorcontrols/?p=182
4.02: Homework 4
1. Give 3 examples of different types of automatic switches typically used in 2-wire control circuits.
2. Name 2 things that the “Hand” position allows us to do in an HOA control circuit.
3. Design, draw and describe (with words) your own HOA circuit. Make sure to label your schematic and that your description indicates how it operates.
4. Is there, or why should there be, a testing/commissioning period of all new motor control circuit installs? You should give at least 2 reasons.
5. What is a pushbutton station?
6. What is a benefit of having multiple pushbutton stations? What is a disadvantage of having multiple pushbutton stations?
7. If I wanted to add an additional stop function to a motor control station, should I wire the new stop in series or parallel with the other stop pushbuttons?
8. If I wanted to add an additional start function to a motor control station, should I wire the new start in series or parallel with the other start pushbuttons?
9. Design, draw and label a motor control circuit that uses 4 pushbutton stations and 4 E-Stops.
10. Explain why it’s best to think of all of the additional push button stations needed before the installation takes place.
5.01: Intermediate Motor Controls
As our circuits get more complex and we’re able to control more systems from various inputs, we’ll need to learn ways to systematically troubleshoot our motors and controls.
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/motorcontrols/?p=205
Once we can troubleshoot basic 3-wire controls, we can easily see how to implement jogging and reversing motor controls.
A YouTube element has been excluded from this version of the text. You can view it online here: openoregon.pressbooks.pub/motorcontrols/?p=205
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/motorcontrols/?p=205
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/motorcontrols/?p=205
A YouTube element has been excluded from this version of the text. You can view it online here: openoregon.pressbooks.pub/motorcontrols/?p=205
5.02: Homework 5
1. What is the first step in troubleshooting any system?
2. What would happen in a scenario where only the primary power to the motor is lost, while pilot-level ladder logic remains functional)?
3. Describe the difference between overloads in manual reset mode and automatic reset mode.
4. What is “jogging” or “inching”
5. When is jogging used?
6. What is in-rush current and what is its proportion compared to normal full-load current?
7. Describe the purpose of a magnetic reversing motor starter and how it functions.
8. What is an interlock and what are the three different types?
9. Why must magnetic reversing motor starters contain an interlock?
10. What types of events may cause an overload?
11. If a motor is running in reverse mode when the overloads are tripped, can the motor be run in forward mode? Also, what is required in order to start the motor in reverse mode again?
12. What happens when the electrical interlocks are removed form a circuit and the reverse button is pressed while the motor is running in the forward direction (mechanical interlocks are in place)? | textbooks/workforce/Electronics_Technology/Book%3A_Troubleshooting_Motors_and_Controls_(Dickson-Self)/04%3A_Lesson_4/4.01%3A_Multiple_Push_Button_Stations.txt |
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/motorcontrols/?p=213
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/motorcontrols/?p=213
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/motorcontrols/?p=213
Testing capacitors
Warning: A good capacitor stores an electrical charge and may remain energized after power is removed. Before touching it or taking a measurement:
1. Turn all power OFF
2. Use your multimeter to confirm that power is OFF
3. Carefully discharge the capacitor by connecting a resistor across the leads. Be sure to wear appropriate personal protective equipment.
To safely discharge a capacitor: After power is removed, connect a 20,000 Ω, 2-5 watt resistor across the capacitor terminals for 20 – 40 seconds. (You can use your multimeter set to volts to confirm the capacitor is fully discharged.)
1. Visually inspect the capacitor. If leaks, cracks, bulges or other signs of deterioration are evident, replace the capacitor.
2. Turn the dial to the Capacitance Measurement mode ( ).
3. For a correct measurement, the capacitor will need to be removed from the circuit and properly discharged.
4. Connect the test leads to the capacitor terminals. Keep test leads connected for a few seconds to allow the multimeter to automatically select the proper range.
5. Read the measurement displayed. Value should fall within specified range (or +/- 10% of stated value). DMM will display OL if a) the capacitance value is higher than the measurement range or b) the capacitor is faulty.
Troubleshooting single-phase motors is one of the most practical uses of a digital multimeter’s Capacitance Function.
A capacitor-start, single-phase motor that fails to start is a symptom of a faulty capacitor. Such motors will continue to run once operating, making troubleshooting tricky. Failure of the hard-start capacitor for HVAC compressors is a good example of this problem. The compressor motor may start, but soon overheat resulting in a breaker trip.
Three-phase power factor correction capacitors are typically fuse protected. Should one or more of these capacitors fail, system inefficiencies will result, utility bills will most likely increase and inadvertent equipment trips of may occur. Should a capacitor fuse blow, the suspected faulty capacitor farad value must be measured and verified it falls within the range marked on the capacitor.
Motor Nameplates
There are many different types of electric motors, and they all have unique parameters, requirements and specifications. Motor nameplates contain information concerning motor performance and mounting parameters, defined by the National Electrical Manufacturers Association (NEMA). These parameters include:
• Manufacturer’s type and frame designation – This can include information such as the frame mounting pattern, shaft diameter and shaft height
• Horsepower – Measure of motor’s mechanical output. This is based on the motor’s full-load torque and speed. Horsepower = Motor Speed x Torque / 5250. If your application’s requirement falls between two horsepower ratings, generally pick the larger-sized motor.
• RPM – Sometimes called “slip speed” (as opposed to synchronous speed). Determined by winding pattern and power frequency.
• Locked-rotor Code Letter – Uses letters A to V to define the locked rotor kVA per HP. Typically, A is the lowest. B is greater than A. C is greater than B, etc. A higher code may require replacing other equipment, such as motor starters to handle greater current.
• Maximum ambient temperature and time rating or duty cycle- Standard motors are rated for continuous duty (24/7) at their rated load and maximum ambient temperature. Specialized motors can be designed for “short-time” requirements where intermittent duty is all that’s needed. These motors can carry a short-time rating from 5 minutes to 60 minutes.
• Voltage – 230V motor running at 208V will be less efficient, but a 480V motor works at 460V because voltage drop is assumed (if motors are designed to handle a 10% voltage difference, then a 480V motor should be able to handle any voltage from 432-528V.
• Frequency – Input frequency (60 Hz in the US, 50 Hz in many other countries)
• Phase – The number of AC power lines supplying the motor
• Current draw – When motor is fully loaded. Unbalanced phases and under voltage can cause current deviation.
• Power factor – Ratio of the active power to the apparent power (at full load).
• Efficiency – Power calculation = (Output / Input) x 100
• Service factor – This will only by on the nameplate if it is higher than one. Service factor (SF) is an indication of how much overload a motor can withstand when operating normally within the correct voltage tolerances. For example, the standard SF for open drip-proof (ODP) motors is 1.15. This means that a 10-hp motor with a 1.15 SF could provide 11.5 hp when required for short-term use. n general, it’s not a good practice to size motors to operate continuously above rated load in the service factor area.
• Wiring diagrams
• Bearing – Drive-end (sometimes called shaft-end) and non-drive-end bearing identification.
6.02: Homework 6
1. Complete the table below
R1 R2 R3 R4 R3//R4 Total
E 10V
I
R 200Ω 300Ω 400Ω 400Ω
1. Create a truth table based upon the ladder diagram below:
1. Create a truth table based upon the ladder diagram below
1. Draw a ladder diagram of a 2-wire circuit using a temperature switch.
1. Draw a ladder diagram of a 3-wire circuit using 2 E-Stops
1. I thought that I wired up the circuit shown below. As soon as I plugged the circuit in, the motor starter coil immediately energized and pulled-in. When I push either STOP button, the coil will de-energize. Give at least two things that could be wrong.
1. I wired up another motor starter, identical to the circuit shown in problem #6. I am 100% sure that all of the wiring is correct. When I plug my circuit in, nothing happens (which is how it should be, right?), but when I press either START button, the coil will not energize. What could be causing this problem? Give at least two things that could be wrong.
1. Using the same circuit that’s shown in problem #6, what voltage should I measure across the coil when it is energized? (Zero, Ghost, or Source)
1. Using the same circuit that’s shown in problem #6, what voltage should I measure across any of the START pushbuttons when the coil is energized? (Zero, Ghost, or Source)
1. How can using a 2-wire circuit be dangerous? | textbooks/workforce/Electronics_Technology/Book%3A_Troubleshooting_Motors_and_Controls_(Dickson-Self)/06%3A_Lesson_6/6.01%3A_Testing_Motor_Components.txt |
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/motorcontrols/?p=221
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/motorcontrols/?p=221
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/motorcontrols/?p=221
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/motorcontrols/?p=221
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/motorcontrols/?p=221
7.02: Homework 7
1. What is another name for an on-delay timer?
2. Draw a timing diagram for the on-delay timer (including signal/control, NO and NC contacts)
3. What’s the difference between a single-function and multi-function timer?
4. Draw the schematic symbol for both the NO and NC contacts of an on-delay timer.
5. Describe a situation in industry where you might want to use a cumulative on-delay timer.
6. Describe the example Jim uses in the first video where an on-delay timer is used to control two conveyor belts. What’s the function of the timer in this case?
7. What is another name for an off-delay timer?
8. Draw a timing diagram for the off-delay timer (including signal/control, NO and NC contacts).
9. Draw the schematic symbol for both the NO and NC contacts of an off-delay timer.
10. Describe the performance of a flash/repeat/recycle timer.
11. Describe the difference between symmetric and asymmetric timers.
12. Describe the function of a positive/rising edge triggered one-shot timer.
13. Draw the timing diagram for a negative/falling edge triggered one-shot timer.
8.01: Motor Drives
A frequently-used component in any modern industry are motor drives, sometimes called variable frequency drives or VFDs. In order to understand how VFDs control the speed of a motor, you must first understand what happens inside an AC induction motor.
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/motorcontrols/?p=282
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/motorcontrols/?p=282
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/motorcontrols/?p=282
Below, Jim Pytel explains an example motor drive by Omron. Use this information as an introduction to the topic. There are MANY different types of motor drives, and they all have their own little idiosyncrasies. Even VFDs made by the same manufacturer may have very different programming steps. READ THE MANUAL for the drive you’re working with. As you become more familiar with these, you’ll be able to quickly find the information you need to set-up your particular drive.
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/motorcontrols/?p=282
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/motorcontrols/?p=282
8.02: Homework 8
1. How can you change the direction of rotation on a three-phase AC motor?
2. The rotating part of a three-phase AC motor is called a __________.
3. The stationary part of a three-phase AC motor is called a ___________.
4. Which three-phase AC motor has a higher RPM, one with 2 poles, or one with 4 poles?
5. When the supplied frequency for a three-phase AC motor increases, does the motor RPM’s increase or decrease?
6. Name one mechanical method to step-up or step-down a motor’s output speed (note: changing the number of poles, while technically correct, is not a method typically used in an industrial environments to change the speed of rotating equipment).
7. In a motor drive, what does the rectifier portion of the drive do?
8. Name three characteristics of an inverter rated motor.
9. Name three of the broad categories that motor drives need to have programmed by the user.
10. What is the purpose of the communication port on a motor drive? | textbooks/workforce/Electronics_Technology/Book%3A_Troubleshooting_Motors_and_Controls_(Dickson-Self)/07%3A_Lesson_7/7.01%3A_Timers.txt |
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/hydraulics/?p=18
Describe the purpose of a fluid power system
Differentiate between fluid power systems and mechanical or electrical systems
Differentiate between hydraulic and pneumatic systems with respect to the fluid medium employed, characteristics, capacity, performance, and cleanliness
Describe a basic fluid power system in terms of power conversion.
Describe the role of a prime mover like a motor or internal combustion engine in a fluid power system.
Draw the schematic symbol for a motor and internal combustion engine.
Describe the role of a pump in a fluid power system. Draw the schematic symbol for a pump and reservoir.
Describe what properties pressure, flow rate, and valve position influence in a fluid power system.
Describe Pascal’s Law and the formula used to relate force, pressure, and area.
Describe the role of an actuator in a fluid power system. Draw the schematic symbol for a cylinder and hydraulic motor.
Comment on the drawbacks of systems composed of numerous stages
Comment on the advantages and disadvantages of fluid power systems
Identify safety concerns associated with fluid power systems.
Comment on sources of inefficiency within a fluid power system
Identify five different types of pressure control valves
Draw the schematic symbol for a pressure gauge, pressure switch, and pressure transducer
List the devices that control flow rate
Draw the schematic symbol for a flow control valve and comment on how they are employed in fluid power systems.
Draw the schematic symbol for flow meters and comment on how they are employed in fluid power systems.
Draw the schematic symbol for a check valve. Differentiate between free flow and blocked direction.
Describe the purpose of a directional control valve in a fluid power system.
Draw the schematic symbol for a 3 position, spring centered, manually actuated directional control valve with a closed center, a straight through position, and a cross connect position
Discuss how the above valve’s position influences a double acting cylinder’s actuation direction when the cap end port is hooked to actuator port A and rod end port is hooked to actuator port B.
Discuss how the above valve’s position influences a double acting cylinder’s actuation direction when the actuator ports are swapped (rod end port is hooked to actuator port A and cap end port is hooked to actuator port B).
Discuss how a double acting cylinder’s actuation direction is influenced when one port is blocked.
Describe the purpose of mechanical limit switches, magnetic proximity switches, and position transducers in a fluid power system.
Differentiate between energy and power and give examples of common energy and power units.
Determine the energy requirement in ft*lbf to move a 500lbf object 12ft.
Determine the power requirement in ft*lbf/s, hp, and W to move a 500lbf object 12ft in 2.3s.
Given a 72% efficient system determine the input power in W necessary to produce 5.6hp output
Given a 79% efficient system determine the output power in hp if 3.2kW was input
01.2: Hydraulics Math
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/hydraulics/?p=24
Given F=pA, solve for p in terms of F and A.
Given F=pA, solve for A in terms of F and p.
Given Q = V/t, solve for V in terms of Q and t
Given Q = V/t, solve for t in terms of v and Q
Comment on pressure and flow rate and how they influence the force and speed of a hydraulic actuator.
List units commonly employed to measure hydraulic quantities
US SI/metric
length
area
volume
pressure
force
flow rate
time
Determine equivalencies for the following values:
1 in => cm
1 lbf => N
1 l => cm3
1 gallon => in3
14.5 psi => bar=> kPa
1 gallon => l
Convert a volume of 0.45 gallon to in3
Convert a volume of 40 in3 to gallons
Convert 650kPa to psi and bar
Convert 18 bar to psi and kPa
Convert 490psi to bar and kPa
Differentiate between the terms cap end, rod, and rod end with respect to area and volume. Draw a picture.
Which volume must be filled to extend a cylinder, the cap end, the rod, or the rod end?
Which volume must be filled to retract a cylinder, the cap end, the rod, or the rod end?
Write the formula used to determine the surface area of a circle.
Write the formula used to determine the surface area of a ring.
Write the formula used to determine the volume of a cylinder.
Write the formula used to determine the volume of a tube (a cylinder with a cylinder removed).
Given cylinder X with the following dimensions calculate the desired quantities:
dcap = 2 ¾ in
drod = ¾ in
travel length = 12 in
Acap =
Arod =
Arod end =
Vcap =
Vrod =
Vrod end =
Given a fixed flow rate of 0.75 gpm calculate the desired quantities for cylinder X:
textend (s) =
tretract (s) =
speedextend (in/s) =
speedretract (in/s) =
Given a pump with a fixed displacement of 0.4 in3/rev is rotated at 1800rpm calculate the flow rate in units of gpm.
Given a motor with fixed speed describe how flow rate can be varied.
Given a pump with fixed displacement describe how flow rate can be varied.
Given cylinder X calculate the desired quantities given the applied load is 2300lbf.
pextend =
pretract =
Given cylinder X calculate the desired quantities given maximum pressure is limited to 670psi.
Fextend MAX =
Fretract MAX = | textbooks/workforce/Electronics_Technology/Hydraulics_and_Electrical_Control_of_Hydraulic_Systems_(Pytel)/1%3A_Introduction/01.1%3A_Introduction_to_Fluid_Power_Systems.txt |
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/hydraulics/?p=27
Define the term actuator and give examples of a rotational electrical actuator and a linear hydraulic actuator.
Draw a pictorial diagram of a double acting hydraulic cylinder. Identify the barrel, piston, rod, cap end plate, rod end plate, rod wiper, cap end port, and rod end port. NOTE: the rod end is often called the “head” end and the cap end is often called the “blind” end.
Draw the schematic symbol for a double acting hydraulic cylinder.
Differentiate between the cap end and rod end. Which has more functional area?
Describe the act of extending and retracting a double acting cylinder in terms of which volumes are filled and which volumes are emptied. Comment on observed differences between extension and retraction speeds given constant flow rate.
Comment on how blocked ports affect extension and retraction of double acting hydraulic cylinders.
Differentiate between static and dynamic seals. Point out static and dynamic seals in a double acting hydraulic cylinder.
Comment on how a gasket is used to form a static seal. Comment on gasket composition and fluid compatibility.
Comment on how O-rings, piston rings and oil form a dynamic seal.
Comment on why oil is used in hydraulic systems.
Describe the cross sections of other dynamic seals.
Comment on the purpose of the rod wiper. Comment on storage of hydraulic equipment and the role of fabric bellows.
Comment on the purpose of a stop tube.
Describe a double rod cylinder and draw its schematic symbol.
Describe a tandem cylinder. Describe a duplex cylinder. Draw the schematic symbols.
Describe how a cushion works. Draw the schematic symbol for a cushion on extension. Draw the schematic symbol for a cushion on retraction. Draw the symbol for a variable cushion.
Draw lug, flange, flush, and tie rod mounted cylinders. Describe the purpose of fixed mounting methods.
Draw trunnion and clevis mounted cylinders. Describe the purpose of pivoting mounts. NOTE: Pivoting mounts are often specified by the location of the pivot point (example: head trunnion vs. center mounted barrel trunnion)
Describe and draw the schematic symbol for a single acting cylinder. Describe the means a single acting cylinder uses to retract.
Describe a ram. Describe how the descent of a lifted object can be controlled.
Describe a telescoping cylinder.
Describe how a spring can be used to apply or remove a brake in the event of pressure loss. Comment on how a spring is a source of hazardous energy.
01.4: General Industrial Safety
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/hydraulics/?p=30
Comment on elements essential to emergency preparedness.
Enroll in a First Aid/CPR/AED class if you are not already certified
Define the purpose of a lock out and tag out program.
Describe lock out devices used for plugs, switches, and valve handles.
Describe how a hasp is utilized with a group of workers and their individual lock and tag.
Define lock out, define tag out, and differentiate between the two terms.
Describe the general procedure to conduct service on a system.
Comment on the purpose of inspecting Personal Protective Equipment (PPE) prior to use.
Differentiate between types and classes of hard hats.
Describe the features and types of eye protection and prescription eyewear.
Describe the purpose of eye wash stations and emergency showers.
Differentiate between ear plugs and ear muffs.
Describe how the NRR of a hearing protection device affects environmental noise.
Describe the time weighted average requirement
Comment on protective clothing and hand protection utilized for specialized industrial tasks (ie: electrical, abrasion resistance, chemicals, etc.).
Comment on machine guards.
Comment on the purpose of protective toes and oil resistant soles.
Comment on when fall arrest systems must be utilized.
Comment on the purpose of a harness and shock absorbing lanyard.
Describe the purpose and function of a ladder climber.
Describe the purpose of suspension trauma mitigation straps.
Describe the purpose of a work positioning lanyard. Describe other uses of a work positioning lanyard.
Describe the purpose of a rescue, retrieval and evacuation device.
Describe how a pre-roped pulley assembly, additional pulleys, slings, and carabiners complement a rescue kit.
Describe the purpose of an exclusion zone and tethering.
Describe the 3 features of a confined space and how environmental testing, attendants, communication, and rescue equipment mitigate the problems associated with confined spaces.
Describe some of the unique safety concerns associated with fluid power systems and best practices to mitigate these hazards.
Describe the purpose of OSHA.
Describe the purpose of ANSI.
Describe the purpose of the NEC.
Describe the purpose of NRTLs and give examples.
Describe the purpose of the NEMA and the IEC and differentiate between them.
Show up to your assigned lab period wearing long pants and closed toed shoes. | textbooks/workforce/Electronics_Technology/Hydraulics_and_Electrical_Control_of_Hydraulic_Systems_(Pytel)/1%3A_Introduction/01.3%3A_Hydraulic_Cylinders.txt |
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/hydraulics/?p=41
Describe Pascal’s Law and the formula used to relate force, pressure, and area. Solve for F in terms of p and A. Solve for p in terms of F and A. Solve for A in terms of F and p.
List common units of force, pressure, and area.
Determine equivalency for psi, Pa, and bar.
If area is kept constant determine how changes in pressure affect force.
If pressure is kept constant determine how changes in area affect force.
If area is kept constant determine how changes in force affect pressure.
If force is kept constant determine how changes in area affect pressure.
Given a force multiplication system with the following dimensions:
d1 = 3/4 in
F1 = 120 lbf
h1 = 4 in
d2 = 1 ¼ in
Calculate A1, p, V1, A2, F2, h2, energyin, energyout
Comment on the differences between the cap end and rod end of a double acting cylinder with respect to functional area.
Explain why the pressure necessary to retract is greater than the pressure necessary to extend with the same force for a double acting cylinder.
Explain why the force of extension is greater than the force of retraction given the same pressure limit for a double acting cylinder.
Given cylinder X with the following dimensions:
dcap = 2 7/8 in
drod = 7/8 in
Calculate pext and pret for cylinder X given the system is tasked with moving a 1350lbf object.
Calculate FextMAX and FretMAX for cylinder X given the system is limited to 640psi.
02.2: Pascal's Law Examples
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/hydraulics/?p=44
02.3: Pressure and Pressure Measurement
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/hydraulics/?p=46
List common units of pressure. Equate psi, bar, and Pa.
Convert 230psi to bar and kPa.
Convert 7.3 bar to psi and kPa.
Convert 440kPa to bar and psi.
Determine the minimum of height of a water tower necessary to ensure at least 30 psi
Describe atmospheric pressure and the sources of variance.
Convert 550psi to psia
Convert 900psia to psig
Define a vacuum
Describe the function of a pressure gauge and draw its schematic symbol.
Differentiate between analog (needle) and digital pressure gauges.
Differentiate between bourdon tube and spring loaded piston (Schrader) gauges and describe the basic operation and constituent parts of both.
Differentiate between pressure switches and pressure sensors (transducers).
Describe set, reset, and span (hysteresis) for a pressure switch.
02.4: Check Valves
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/hydraulics/?p=48
Describe the basic purposes of valves in fluid power systems.
Define the terms: body, ports/ways, spool, poppet, seal, springs, actuation/adjustment methods
Describe the different valve mounting methods: inline, subplate, manifold, cartridge, stack
Draw the schematic symbol and cutaway view of a basic poppet style check valve. Identify direction of free flow. Identify direction of blocked flow.
Describe how a primitive pressure relief valve can be created with a check valve.
Define cracking and full open pressure.
Discuss the main disadvantage of a basic poppet style check valve in the free flow direction and how a right angle check valve overcomes this disadvantage. Draw a cutaway view of a right angle check valve.
Draw the schematic symbol and cutaway view of a restriction (orifice) style check valve. Identify direction of free flow. Identify direction of restricted flow. Describe how a restriction (orifice) style check valve works.
Draw the schematic symbol and cutaway view of a pilot to open check valve. Describe how a pilot to open check valve works in the absence and presence of pilot pressure.
Draw the schematic symbol and cutaway view of a pilot to close check valve. Describe how a pilot to close check valve works in the absence and presence of pilot pressure.
Describe how check valves are employed in the following applications: foot valves, manual pumps, filters in bidirectional systems, quick disconnects, valve bypasses, clogged filter bypasses
Determine how these 4 flow control valves with check valve bypasses influence speed of extension or retraction.
02.5: Pressure Relief Valves
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/hydraulics/?p=55
Describe the purpose of a pressure relief valve
Describe scenarios that call for pressure relief
Draw the schematic symbol for a rupture/burst disc and discuss its purpose and method of operation.
Draw the schematic symbol for a pressure relief valve and describe the purpose of the individual elements.
Describe how a check valve and heavy bias spring can be used to create a primitive pressure relief valve.
Draw a cutaway view of a spool type direct acting pressure relief valve. Describe its operation.
Describe the terms overshoot, set, reset, and span (hysteresis)
Define cracking pressure and pressure override. Discuss the influence of pressure override for actuators operating near the set point.
Differentiate between the terms pilot (control) and primary (power)
Draw a cutaway view of a balanced piston type pilot operated pressure relief valve. Describe its operation.
Describe the principle advantage of pilot operated pressure relief valves over direct acting pressure relief valves
Comment on observed properties of systems with malfunctioning, improperly set, or improperly connected pressure relief valves.
Comment on the efficiency of systems that actuate the pressure relief valve frequently.
Comment on alternate methods to prevent overpressure events without the necessity of actuating the pressure relief valve.
02.6: Example Pilot Operated Pressure Relief Valve
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/hydraulics/?p=57 | textbooks/workforce/Electronics_Technology/Hydraulics_and_Electrical_Control_of_Hydraulic_Systems_(Pytel)/2%3A_Pascal's_Law_and_Hydraulic_Components/02.1%3A_Pascal%27s_Law.txt |
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/hydraulics/?p=59
Describe the purpose of a valve in a fluid power system
Describe the purpose of a directional control valve in a fluid power system
Define the following features of directional control valves: positions, ports/ways, return springs, actuation method, deactivated state
Draw the schematic symbol for a 2 position, 2 way, solenoid actuated, spring offset, NC directional control valve. Describe its behavior and use in a fluid power system.
Draw the schematic symbol for a 2 position, 2 way, solenoid actuated, spring offset, NO directional control valve. Describe its behavior and use in a fluid power system.
Draw the schematic symbol for a manual override and discuss its purpose
Draw the schematic symbol for a 2 position, 3 way, manually actuated directional control valve spring offset to a deactivated position that blocks flow at 2 and allows flow from 1 to 3. In its activated state it allows flow from 2 to 3 and blocks flow at 1. Draw three different configurations of this valve.
1. selector valve – 1 A, 2 P, 3 B
2. spring retracted, hydraulically extended single acting cylinder – 1 T, 2 A, 3 P
3. spring retracted, hydraulically extended single acting cylinder – 1 P, 2 A, 3 T
Draw the schematic symbol for a 2 position, 3 way, solenoid actuated directional control valve, spring offset to a position that dumps A to T and when activated routes P to A, describe how this can be used in a failsafe braking application
Draw the schematic symbol for a purposely blocked or plugged port, describe how blocked ports can be used to change the functionality of a directional control valve.
Draw the schematic symbol for a 2 position, 4 way, manually actuated directional control valve used to control a double acting cylinder. Describe the cross connect position. Describe the straight through position.
Describe detents used to position a valve. Describe how an automatic detent with kickout works. Describe the operation of a double solenoid 2 position valve with detents.
Draw the schematic symbol for a 3 position, 4 way, manually actuated directional control valve used to control a double acting cylinder. Describe the closed center position and how it affects the actuator and pressure relief valve.
Describe the tandem center position and how it affects the actuator and pressure relief valve.
Describe the float center position and how it affects the actuator and pressure relief valve.
Describe the open center position and how it affects the actuator and pressure relief valve.
Describe the behavior of a double acting cylinder with both cap and rod end at the same pressure.
Use these cutaway diagrams to describe how the spool affects the position of a directional control valve. Label each position given ports are assigned: A, P, B, T
Describe how flow control restrictions are implemented in a directional control valve and their purpose.
Describe what check valves in a directional control valve position box imply
Describe the shape of the pressure drop for different flow rates performance curve and how to read it
Describe the shape of the operating limits performance curve and how to read it
Identify common entries found on a directional control valve data sheet (Bul 2531-M11 D1VL Data Sheet)
02.8: Example Directional Control Valve
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/hydraulics/?p=66 | textbooks/workforce/Electronics_Technology/Hydraulics_and_Electrical_Control_of_Hydraulic_Systems_(Pytel)/2%3A_Pascal's_Law_and_Hydraulic_Components/02.7%3A_Directional_Control_Valves.txt |
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/hydraulics/?p=68
Discuss the advantages and disadvantages of representing hydraulic components using pictorial, cutaway, and schematic symbols
Differentiate between working, pilot, and drain lines and show how these lines are depicted schematically
Differentiate between schematically connected and unconnected fluid conductors
Describe an enclosure and how enclosures are depicted schematically.
Describe which fluid(s) these colors represent in a hydraulic schematic
Red
Blue
Yellow
Orange (2)
Green (2)
Purple
Define the purpose of these general shapes in a hydraulic schematic:
Circle
Square
Diamond
Slanting Arrow
Define a prime mover. Draw the schematic symbol for a motor and internal combustion engine.
Define a pump. Draw the schematic symbol for a fixed displacement pump, variable displacement pump, pressure compensated variable displacement pump, and manual pump. Differentiate between these types of pumps.
Define the purpose of a case drain and draw the schematic symbol.
Define a coupling. Draw the schematic symbol for a shaft linking a prime mover and pump.
Define a reservoir. Draw the schematic symbol for an atmospheric/vented reservoir and pressurized reservoir.
Define a hydraulic motor. Draw the schematic symbol.
Define a hydraulic cylinder. Draw the schematic symbol for a double acting hydraulic cylinder, a hydraulically extended spring retracted single acting cylinder, a spring extended hydraulically retracted single acting cylinder, and single acting ram. Discuss how these cylinders extend and retract. Describe the purpose of a vent port on a single acting cylinder.
Draw the schematic symbol for a double rod cylinder, a tandem/duplex cylinder, a telescoping cylinder, and an intensifier.
Draw the schematic symbol for a double acting cylinders with a fixed cushion on extension, a fixed cushion on retraction, and a fixed cushion on extension and retraction. Do the same for variable cushions.
Identify the purpose of a pressure relief valve and draw the schematic symbol.
Identify the purpose of a burst/rupture disc and draw the schematic symbol. (see the pressure relief valve lecture)
Identify the purpose of a directional control valve. Draw the schematic symbol for the following directional control valves and discuss the uses of these valves:
2 position, 2 way, solenoid actuated directional control valve spring offset into the NC position featuring a manual override
2 position, 3 way, manually actuated directional control valve spring offset into a position that dumps A to T
2 position, 4 way, solenoid actuated directional control valve with detents featuring a cross connect and straight through position
3 position, 4 way, manually actuated directional control valve, spring centered into a closed center position featuring a straight through and cross connect position
Differentiate between closed, tandem, float, and open center positions. Draw the schematic symbols.
Identify the purpose of a check valve, pilot to open check valve, pilot to close check valve, restriction/orifice type check valve, and manual shutoff valve. Draw the schematic symbol for these devices and discuss how these valves operate.
Identify the purpose of a flow control valve and draw the schematic symbol for the following devices: fixed flow control valve, variable flow control valve, variable flow control valve with check valve bypass, pressure compensated variable flow control valve with check valve bypass, pressure and temperature compensated variable flow control valve with check valve bypass. For flow control valves with check valve bypass identify direction of free flow and controlled flow.
Identify the purpose of a pressure control valve and draw the schematic symbol for the following devices: pressure relief valve, sequence valve, pressure reducing valve, counter balance valve, unloading valve.
Discuss how the following characteristics assist in identifying pressure control valves:
Pilot line
Deactivated state
Check valve bypass
Internal vs external drain
Location and perceived function
Identify the purpose and general operation principle of an accumulator and draw the schematic symbol for a gas charged accumulator, spring loaded accumulator, and weighted accumulator. Discuss any safety precautions regarding accumulators.
Identify the purpose and draw the schematic symbol for the following devices: pressure gauge/manometer, quick disconnect inspection ports, pressure switch (hydraulic and electric), pressure sensor, flow meter, limit switch, magnetic proximity switch (hydraulic and electric)
Identify the purpose and draw the schematic symbol for the following devices: filter, filter with check valve bypass, heater, cooler, cooler with liquid heat transfer fluid, cooler with gas heat transfer fluid. Discuss the purpose of counter flow in heat exchangers.
Define a hydraulic power unit (HPU). Identify devices commonly found in an HPU.
Identify the purpose and draw the schematic symbol for a rotary hydraulic coupling. | textbooks/workforce/Electronics_Technology/Hydraulics_and_Electrical_Control_of_Hydraulic_Systems_(Pytel)/2%3A_Pascal's_Law_and_Hydraulic_Components/02.9%3A_Hydraulic_Schematics.txt |
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/hydraulics/?p=72
Describe flow paths in basic series hydraulic circuits
Describe the actuation sequence of actuators in a series relationship.
Discuss the source of differences in travel length and speed for series hydraulic circuits.
Given two cylinders with the following dimensions in a series relationship, calculate the extension distance of the downstream cylinder given the upstream cylinder fully extends
cap = 1 3/4”
rod = 5/8
travel = 6”
Given the dimensions of the upstream cylinder are to remain fixed, determine the diameter of the downstream cylinder such that it fully extends 6” when the upstream cylinder reaches the limits of travel.
Given two cylinders with the following dimensions in a series relationship, calculate the maximum extension force the system is capable of exerting with the downstream cylinder given input to the upstream cylinder’s cap in limited to 490psi.
cap = 1 3/4”
rod = 5/8
travel = 6”
Given the downstream cylinder is loaded with an 800lbf object determine the pressure in the cap end of the downstream cylinder, the force exerted by the upstream cylinder, and the pressure in the cap end of the upstream cylinder.
Comment on advantages and disadvantages of pressure intensification for series hydraulic circuits.
Given an intensifier with the following dimensions, calculate the output pressure given an input pressure of 80psi.
din = 3”
dout= 3/4”
Describe flow paths in basic parallel hydraulic circuits.
Given two cylinders in a parallel relationship with the following dimensions determine the extension sequence if cylinder A is loaded with a 500lbf load and cylinder B is loaded with a 600lbf load. Calculate the extension pressure necessary to move A. Calculate the extension pressure necessary to move B.
cap = 1 3/4”
rod = 5/8
travel = 6”
Given two cylinders in a parallel relationship with the following dimensions calculate the extension sequence if the cylinders are both loaded with 800lbf loads. Calculate the extension pressure necessary to move A. Calculate the extension pressure necessary to move B.
A cap = 1 3/4”
A rod = 5/8
A travel = 6”
B cap = 2”
B rod = 5/8
B travel = 6”
Discuss the purpose of a mechanical yoke, balanced loads, and flow control valves in a parallel relationship.
Given two cylinders in a parallel relationship with the following dimensions mechanically yoked together calculate the extension pressure necessary to move a perfectly balanced 960lbf object.
cap = 1 3/4”
rod = 5/8
travel = 6”
03.2: Accumulators
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/hydraulics/?p=76
List common functions of accumulators in a hydraulic system
List the two general classes of accumulators.
List the two types of mechanical accumulators. Describe each one. Draw the schematic symbol.
List the three types of hydro-pneumatic accumulators. Draw the schematic symbol. Describe each one. Draw the cutaway view of each type.
Draw the cutaway view of a bladder type hydro-pneumatic accumulator in various states of charge. Identify various components and their function.
Define precharge.
Describe why dry nitrogen or another inert gas is used to precharge accumulators.
Use this schematic to describe how an accumulator influences a hydraulic circuit. Describe the purpose of the flow control valve with check valve bypass on the accumulator. Describe how a technician would release the stored energy in the accumulator.
Differentiate between the terms adiabatic and isothermal with respect to charging and discharging an accumulator
List which data is required to properly size a Parker A series piston accumulator. Given an application with a minimum pressure of 500psi determine the recommended precharge for a Parker A series piston accumulator. (Parker A Series Piston Accumulator datasheet)
Draw a cutaway view of a piston style hydro-pneumatic accumulator. Identify the internal components.
Differentiate between failure modes and loss of precharge for piston, diaphragm, and piston style hydro-pneumatic accumulators
03.3: Fluid Properties
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/hydraulics/?p=82
List the purposes of fluid in a fluid power system
Define lubricity and the factors that influence lubricity
Describe why petroleum based oil is the liquid of choice for most hydraulic systems
Comment on the observed compressibility of liquids under pressure.
Define density.
Define specific weight, differentiate between it and density. Look up the specific weight of oil, water, and other common substances.
Define specific gravity. Look up the specific gravity of oil and other common substances.
Name the tool used to measure specific gravity of a liquid. Describe why a discharged battery has an SG reading closer to 1. Comment on properties that influence density, specific weight, and specific gravity.
Define viscosity.
Describe how viscosity is measured using a Saybolt viscometer.
Comment on the viscosity measurement of a thick fluid using units of SSU. Comment on the viscosity measurement of a thin fluid using units of SSU. Look up the viscosity of common liquids.
Comment on the advantages and disadvantages of liquids with high viscosity measurements.
Comment on the advantages and disadvantages of liquids with low viscosity measurements.
List another common viscosity unit.
Define viscosity index (VI). Comment on how temperature ordinarily affects viscosity. Comment on VI for liquids exhibiting excellent and poor viscosity stability.
Comment on manufacturers specifying viscosity measurements for data sheets.
Define pour point. Comment on the magnitude of a liquid’s pour point an application that must work in an extremely cold environment.
List common additives in a hydraulic system.
Comment on additive compatibility
03.4: Filtration and Conditioning
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/hydraulics/?p=84
Describe the purpose of fluid in a fluid power system.
Define contaminant. Identify sources of contaminants and give examples.
Describe how oil can become a contaminant.
Describe the negative effects of contaminants in a fluid power system.
Describe the unit commonly used to measure contaminants.
Describe methods of reducing contaminant entry into a system.
Define a filter and describe a filter’s construction.
Define and differentiate between the terms nominal and absolute rating for a filter.
Define a strainer and differentiate between strainers and filters. Describe common strainer locations. Describe mesh count.
Describe a clogged filter bypass and indicator
Define beta ratio.
Calculate the beta ratio for a filter that has 1000 particles greater than 10µm upstream and 10 particles greater than 10µm downstream.
List different filter locations. Discuss the pressure requirements and describe their operation.
Describe why filters are ordinarily unidirectional. Draw an arrangement of check valves that ensures unidirectional flow through a filter given a bidirectional flow path.
Describe the additional function of a kidney loop/offline filter with respect to viscosity.
List the 3 particle sizes of concern for the ISO Standard 4406:1999.
Determine the particle count for an oil with an 18/16/13 cleanliness rating
Discuss why cleanliness standards must be considered for different applications.
Describe conditioning and differentiate between it and filtration.
Describe tube in shell and baffle heat exchangers employing liquid heat transfer fluids and comment on the purpose of counter flow.
Comment on the purpose of a reservoir and how it is used to passively condition fluid.
Range Code Particles per mL
from up to
24 80000 160000
23 40000 80000
22 20000 40000
21 10000 20000
20 5000 10000
19 2500 5000
18 1300 2500
17 640 1300
16 320 640
15 160 320
14 80 160
13 40 80
12 20 40
11 10 20
10 5 10
9 2.5 5
8 1.3 2.5
7 0.64 1.3
6 0.32 0.64
03.5: Regenerative Extension
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/hydraulics/?p=86
Given volume (V) and time (t) solve for flow rate (Q).
Given time (t) and flow rate (Q) solve for volume (V).
Given flow rate (Q) and time (t) solve for volume (V).
Given a cylinder with the following dimensions:
dcap =2 ½ in
drod = 1 in
travel = 24 in
Calculate the time to fully extend the cylinder and the time to fully retract the cylinder in units of seconds given a constant flow rate of 2.3 gpm. Additionally, calculate maximum extension and retraction force given maximum pressure of 400psi.
Determine the response of a double acting cylinder given equal pressure on the cap and rod end. Use Pascal’s Law to explain your answer.
Determine the force and functional area imbalance between cap and rod end of the above cylinder given equal pressure on the cap and rod end.
Describe flow patterns within a double acting cylinder in regenerative extension mode.
Identify the volume differential between the cap end at full extension and the rod end at full retraction.
Compare the extension force and speed for a cylinder in regenerative extension mode with one in normal extension mode.
Given the above example cylinder calculate the extension speed in units of seconds while in regenerative extension mode.
Given a cylinder with the following dimensions and a system with the following parameters:
dcap =3 in
drod = 1 ¼ in
travel = 16 in
Q = 1.8gpm
Pmax = 500psi
Calculate the time to fully extend the cylinder the cylinder in units of seconds and maximum extension force in normal extension mode:
Calculate the time to fully extend the cylinder the cylinder in units of seconds and maximum extension force in regenerative extension mode:
Describe applications for regenerative extension.
Describe the physical characteristics of a 2:1 cylinder and its application in a system that routes pressurized flow to both cap and rod end serving to extend the cylinder and a cross connect position serving to retract the cylinder.
Given a 2:1 cylinder with the following dimensions:
dcap =1 ½ in
drod = 1.06066017178 in
travel = 12 in
Q = 0.9gpm
Pmax = 700psi
Calculate the extension and retraction force and the time to fully extend and retract given extension in regenerative mode.
Describe the operation of this system employing a manually actuated 3 position directional control valve spring offset into the cross connect position with a soft and hard stop.
Describe the purpose of each position for this directional control valve.
Describe the operation of this system employing additional directional control valves. | textbooks/workforce/Electronics_Technology/Hydraulics_and_Electrical_Control_of_Hydraulic_Systems_(Pytel)/3%3A_Hydraulic_Applications/03.1%3A_Series_and_Parallel_Hydraulic_Circuits.txt |
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/hydraulics/?p=106
Describe the role of pumps in a hydraulic system.
Describe the role of prime movers in a hydraulic system.
Define flow rate. List the formulas used to calculate flow rate.
Define displacement.
Discuss two methods the prime mover and pump combination can directly influence flow rate.
Discuss how a system can control flow rate given a fixed displacement pumps operated at a fixed rotational speed.
Discuss the purpose of the check valve bypass for a flow control valve.
List the characteristics of a positive displacement pump. Compare and contrast this with a non-positive displacement pump.
List the sequence of operation of a positive displacement pump.
Comment on viscosity requirements, conditioning needs, and cleanliness standards for positive displacement pumps.
Describe the pressure requirements for these two different system given the following scenarios: moving unloaded actuator, moving loaded actuator, actuator stalled at the limits of travel, centered directional control valve
Describe why a tandem center directional control valve would not work for this circuit.
Describe why displacement ordinarily decreases at higher pressures.
Describe why rotational speed ordinarily decreases at higher pressures.
Describe why flow rate ordinarily decreases at higher pressures.
Describe this family of curves.
Given a pump with a fixed displacement of .35CIR at ideal conditions, calculate flow rate in gpm if the pump was driven at exactly 1800 rpm.
Describe this family of curves for a pump rotated at a nominal speed.
Comment on how actuator speed is influenced by increased pressure requirements.
Define volumetric efficiency.
Given a pump with a fixed displacement of .35CIR at ideal conditions decreased to .33CIR at 1000psi, calculate the volumetric efficiency at 1000psi.
Describe why pump manufacturers specify drive speed, fluid properties, and pressure ranges.
Define pump overall efficiency and the formula used to calculate pump overall efficiency
Write the formula used to calculate hydraulic power when pressure is expressed in units of psi, flow rate is expressed in units of gpm, and power is expressed in units of hp.
Given a pressure of 1500psi and a flow of 2gpm, calculate the hydraulic power output of the pump. Given this output necessitated the prime mover supply 2.4hp of mechanical power, determine the overall efficiency of the pump.
List three common positive displacement pumps employed in hydraulic systems. Comment whether the pumps are fixed or variable displacement.
Differentiate between fixed and variable displacement pumps. Discuss the advantages and disadvantages of variable displacement pumps.
Describe how the pressure compensated variable displacement pump prevents the main pressure relief valve from actuating in this circuit when the actuator reaches the limits of travel or when the valve is placed in the center position.
Define firing pressure. Describe why the main pressure relief valve must be above the compensator setting. Explain high pressure standby.
Describe the advantages and applications for circuits using pressure compensated variable displacement pumps.
Describe how a shuttle (OR) valve works. Draw the schematic symbol.
Describe a load sensing operation making use of a pressure compensated variable displacement pump.
Define cavitation and identify possible sources of cavitation.
Define aeration and identify possible sources of aeration.
Define pseudo-cavitation and identify possible sources of pseudo cavitation.
Differentiate between cavitation, aeration, and pseudo cavitation.
Comment on the observable effects of systems encountering cavitation, aeration, and pseudo-cavitation problems | textbooks/workforce/Electronics_Technology/Hydraulics_and_Electrical_Control_of_Hydraulic_Systems_(Pytel)/4%3A_Pumps_and_Flow_Control/04.1%3A_Hydraulic_Pumps.txt |
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/hydraulics/?p=113
Describe the sequences of a positive displacement pump.
Differentiate between fixed and variable displacement pumps.
Classify and describe the three types of positive displacement pumps commonly employed in hydraulic systems.
Describe how fixed displacement pumps vary flow rate.
List the four types of gear pumps and identify the most common type.
Identify parts in an external gear pump and draw a diagram of an external gear pump.
Describe how a gear pump executes the phases of a positive displacement pump.
Describe where dynamic and static seals can be found in a gear pump.
Take apart a gear pump. Identity internal components.
Find the data sheet for a gear pump. Identify displacement, drive speed range, viscosity range, fluid cleanliness requirements, and other pertinent specifications. Explain flow rate as a function of pressure, flow rate as a function of drive speed, and other pertinent charts. (Prince SP25A Gear Pump Datasheet)
Briefly describe lobe, internal, and gerotor type gear pumps.
04.3: Vane Pumps
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/hydraulics/?p=116
Describe the sequences of a positive displacement pump.
Differentiate between fixed and variable displacement pumps.
Classify and describe the three types of positive displacement pumps commonly employed in hydraulic systems.
Describe how a variable displacement pump can vary flow rate.
List the two main types of vane pumps
Identify parts in an unbalanced vane pump and draw a diagram.
Describe how an unbalanced vane pump executes the phases of a positive displacement pump.
Describe how a variable displacement unbalanced vane pump works.
Define eccentricity and concentricity. Identify which positions produce max/min flow rate.
Describe the main disadvantage of unbalanced vane pumps and how balanced vane pumps solve this issue.
Identify parts in balanced vane pump and draw a diagram.
Describe how a balanced vane pump executes the phases of a positive displacement pump.
Take apart a fixed displacement unbalanced vane pump. Identity internal components.
Take apart a variable displacement unbalanced vane pump. Identity internal components. (NOT SHOWN IN LECTURE)
Take apart a fixed displacement balanced vane pump. Identity internal components.
Define the term cartridge. Identify advantages of cartridges when repairing vane pumps.
Find the data sheet for a vane pump. Identify displacement, drive speed range, viscosity range, fluid cleanliness requirements, and other pertinent specifications. Explain flow rate as a function of pressure, flow rate as a function of drive speed, and other pertinent charts. (Vane Pump Data Sheet Parker T6C Balance Vane Pump Datasheet)
04.4: Piston Pumps
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/hydraulics/?p=118
List the four main types of piston pumps.
Define the terms axial and radial.
Identify parts in an axial piston pump and draw a diagram.
Pronounce the term “swash plate” correctly. Have your instructor verify correct pronunciation.
Describe how an axial piston pump executes the phases of a positive displacement pump.
Describe how a variable displacement axial piston pump works.
Identify which swash plate positions produce max/min flow rate.
Describe a bent axis piston pump.
Describe a radial piston pump.
Describe a rotating cam radial piston pump.
Take apart a piston pump. Identity internal components.
Find the data sheet for a piston pump. Identify displacement, drive speed range, viscosity range, fluid cleanliness requirements, and other pertinent specifications. Explain flow rate as a function of pressure, flow rate as a function of drive speed, input power requirements as a function of pressure, case drain flow as a function of pressure, and other pertinent charts. (Piston Pump Data Sheet Parker PV Axial Piston Pump Datasheet)
04.5: Flow Control Valves
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/hydraulics/?p=120
Describe how restriction style flow control valves control flow in a hydraulic system making use of a fixed displacement pump and a pressure relief valve.
Draw the schematic symbols for the following devices:
fixed flow control valve
adjustable flow control valve
adjustable flow control valve with check valve bypass
pressure compensated adjustable flow control valve with check valve bypass
temperature and pressure compensated adjustable flow control valve with check valve bypass
Given the orientation of this adjustable flow control valve with check valve bypass determine the direction of free flow and the direction of controlled flow.
Draw a cutaway view of an adjustable flow control valve with check valve bypass and discuss how it functions.
Describe how an adjustable flow control valve with check valve bypass responds to these scenarios:
input pressure increases and load stays the same
input pressure decreases and load stays the same
input pressure stays the same and load decreases
input pressure stays the same and load increases
input pressure and load return to initial conditions
Draw a cutaway view of a pressure compensated adjustable flow control valve with check valve bypass and discuss how it functions.
Describe how a pressure compensated adjustable flow control valve with check valve bypass responds to these scenarios:
input pressure increases and load stays the same
input pressure decreases and load stays the same
input pressure stays the same and load decreases
input pressure stays the same and load increases
input pressure and load return to initial conditions
Discuss how a temperature and pressure compensated adjustable flow control valve with check valve bypass functions.
Describe how a pressure compensated adjustable flow control valve with check valve bypass enhances the performance of multi actuator systems.
Discuss how a bypass type flow control valve works and differentiate between it and a restriction style flow control valve.
Discuss means other than manually changing flow rate.
Describe lunge control.
04.6: Flow Control Methods
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/hydraulics/?p=125
Draw a meter in extension arrangement using an adjustable flow control valve with check valve bypass.
Draw a meter in retraction arrangement using an adjustable flow control valve with check valve bypass.
Describe why meter in configurations are not used to control the descent of a lifted object or negative or overrunning loads.
Draw a meter out retraction arrangement using an adjustable flow control valve with check valve bypass.
Draw a meter out extension arrangement using an adjustable flow control valve with check valve bypass.
Discuss pressure intensification.
Discuss how a meter out flow control arrangement can control the descent of a lifted object or a negative or overrunning load.
Draw a bypass arrangement using an adjustable flow control valve.
04.7: Bottle Jacks and Manual Backup Pumps
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/hydraulics/?p=127
Describe the operation of a bottle jack using this diagram. Discuss pumping action, force multiplication, meter out flow control, and pressure relief.
Comment on inspection and troubleshooting procedures for “broken” bottle jacks.
Describe the regular and override operation of this fail safe braking system making use of a manual backup pump. | textbooks/workforce/Electronics_Technology/Hydraulics_and_Electrical_Control_of_Hydraulic_Systems_(Pytel)/4%3A_Pumps_and_Flow_Control/04.2%3A_Gear_Pumps.txt |
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/hydraulics/?p=132
List the 5 main types of pressure control valves. Draw their associated schematic symbols.
Identify the 5 main characteristics used to classify pressure control valves.
Describe the purpose of a pilot line. Describe the schematic symbol for a pilot line.
Identify pressure control valves that make use of internal pilot lines on their primary, or input, port.
Identify pressure control valves that make use of internal pilot lines on their secondary, or output, port.
Identify pressure control valves that make use of external/remote pilot lines.
Identify pressure control valves that have a NC deactivated state.
Identify pressure control valves that have a NO deactivated state.
Identify pressure control valves that have a check valve bypass. Identify why a check valve bypass is necessary.
Identify pressure control valves that do not have a check valve bypass. Identify why a check valve bypass is not necessary.
Identify pressure control valves that have an internal drain. Identify why an external drain is not necessary.
Identify pressure control valves that have an external drain. Identify why an external drain is necessary. Describe the schematic symbol for an external drain.
Identify customary locations for the 5 main pressure control valves.
Describe a pressure relief valve using the 5 main characteristics used to classify pressure control valves.
Draw the cutaway diagram of a pilot operated pressure relief valve with a vent port.
Describe the basic operation of a balanced piston style pilot operated pressure relief valve.
Describe the main purpose of the vent port.
05.2: Sequence Valves
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/hydraulics/?p=134
NOTE: first 13 entries are REVIEW of pressure control valve family
List the 5 main types of pressure control valves. Draw their associated schematic symbols.
Identify the 5 main characteristics used to classify pressure control valves.
Describe the purpose of a pilot line. Describe the schematic symbol.
Identify pressure control valves that make use of internal pilot lines on their primary, or input, port.
Identify pressure control valves that make use of internal pilot lines on their secondary, or output, port.
Identify pressure control valves that make use of external pilot lines.
Identify pressure control valves that have a NC deactivated state.
Identify pressure control valves that have a NO deactivated state.
Identify pressure control valves that have a check valve bypass. Identify why a check valve bypass is necessary.
Identify pressure control valves that do not have a check valve bypass. Identify why a check valve bypass is not necessary.
Identify pressure control valves that have an internal drain. Identify why an external drain is not necessary.
Identify pressure control valves that have an external drain. Identify why an external drain is necessary. Describe the schematic symbol for an external drain.
Identify customary locations for the 5 main pressure control valves.
Describe a sequence valve using the 5 main characteristics used to classify pressure control valves.
Identify functions of the P, S, D, and X ports for a sequence valve
Describe how the orientation of the check valve bypass influences this actuator’s action.
Describe the basic operation of a sequence valve.
Describe operation of this multi actuator clamp and bend hydraulic circuit.
Describe the operation of this multi actuator hydraulic circuit making use of a sequence valve on the cap end of the bend cylinder. Assume the set value of the sequence valve is 400psi and the main pressure relief valve is set to 800psi.
Identify potential disadvantages of coordinating actuation sequence using solely pressure input.
Describe the operation of this multi actuator hydraulic circuit making use of a sequence valve on the cap end of the bend cylinder and another sequence valve on the rod end of clamp cylinder.
Describe the operation of this hydraulic circuit making use of a sequence valve with an external remote pilot used to coordinate two separate actuators (stabilizer boom and crane) using two independent directional control valves.
Differentiate between the operation of a normal versus a kick down style sequence valve.
Describe the operation and advantages of this multi actuator hydraulic circuit making use of a kick down style sequence valve.
Describe how a sequence valve can present an advantage when used as a pressure relief valve in this hydraulic circuit.
Describe how this sequence valve and check valve can be used to brake a unidirectional hydraulic motor.
Describe how these two sequence valves can be used to brake a bidirectional hydraulic motor.
Describe how the set value of the above sequence valves influences the deceleration rate of the hydraulic motor.
Identify the purpose of a makeup check valve.
05.3: Pressure Reducing Valves
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/hydraulics/?p=145
NOTE: first 13 entries are REVIEW of pressure control valve family
List the 5 main types of pressure control valves. Draw their associated schematic symbols.
Identify the 5 main characteristics used to classify pressure control valves.
Describe the purpose of a pilot line. Describe the schematic symbol.
Identify pressure control valves that make use of internal pilot lines on their primary, or input, port.
Identify pressure control valves that make use of internal pilot lines on their secondary, or output, port.
Identify pressure control valves that make use of external pilot lines.
Identify pressure control valves that have a NC deactivated state.
Identify pressure control valves that have a NO deactivated state.
Identify pressure control valves that have a check valve bypass. Identify why a check valve bypass is necessary.
Identify pressure control valves that do not have a check valve bypass. Identify why a check valve bypass is not necessary.
Identify pressure control valves that have an internal drain. Identify why an external drain is not necessary.
Identify pressure control valves that have an external drain. Identify why an external drain is necessary. Describe the schematic symbol for an external drain.
Identify customary locations for the 5 main pressure control valves.
Describe a pressure reducing valve using the 5 main characteristics used to classify pressure control valves.
Describe the basic operation of a pressure reducing valve.
Describe how the orientation of the check valve bypass influences this actuator’s action.
Identify functions of the P, R, and D ports for a pressure reducing valve
Differentiate between constant pressure type pressure reducing valves and constant reduction type pressure reducing valves.
Describe operation of this multi actuator hydraulic circuit making use of a pressure reducing valve.
Describe operation of this multi actuator hydraulic circuit making use of both a pressure reducing valve and a sequence valve.
Discuss how set values of the pressure reducing valve, sequence valve, and main pressure relief valve influence the proper functionality of the above system. | textbooks/workforce/Electronics_Technology/Hydraulics_and_Electrical_Control_of_Hydraulic_Systems_(Pytel)/5%3A_Pressure_Control/05.1%3A_Vented_and_Remote_Controlled_Pressure_Relief_Valves.txt |
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/hydraulics/?p=150
NOTE: first 13 entries are REVIEW of pressure control valve family
List the 5 main types of pressure control valves. Draw their associated schematic symbols.
Identify the 5 main characteristics used to classify pressure control valves.
Describe the purpose of a pilot line. Describe the schematic symbol.
Identify pressure control valves that make use of internal pilot lines on their primary, or input, port.
Identify pressure control valves that make use of internal pilot lines on their secondary, or output, port.
Identify pressure control valves that make use of external pilot lines.
Identify pressure control valves that have a NC deactivated state.
Identify pressure control valves that have a NO deactivated state.
Identify pressure control valves that have a check valve bypass. Identify why a check valve bypass is necessary.
Identify pressure control valves that do not have a check valve bypass. Identify why a check valve bypass is not necessary.
Identify pressure control valves that have an internal drain. Identify why an external drain is not necessary.
Identify pressure control valves that have an external drain. Identify why an external drain is necessary. Describe the schematic symbol for an external drain.
Identify customary locations for the 5 main pressure control valves.
Describe an unloading valve using the 5 main characteristics used to classify pressure control valves.
Describe the basic operation of an unloading valve.
Identify functions of the P, T, and X ports for an unloading valve
Describe operation of this high-low pumping circuit making use of an unloading valve. Assume pump A is high flow/low pressure and pump B is low flow/high pressure. Assume set value of unloading valve is half that of the main pressure relief valve. Identify the purpose of the check valve between pump A and B.
When pressure in the external pilot line reaches the set value of the unloading valve identify the magnitude of the pressure differential across the unloading valve when it opens.
Identify 2 general applications of a high-low pumping circuit.
Compare and contrast regenerative extension with high-low pumping circuits making use of an unloading valve.
Describe operation of this hydraulic circuit making use of an unloading valve and an accumulator. Identify problems with this circuit when the unloading valve is pilot operated.
Use this hydraulic circuit and diagram of two pilot darts to describe the general operation of a differential unloading relief valve.
Describe the operation of this hydraulic circuit making use of a differential unloading relief valve and an accumulator.
Identify the source of the differential range experienced during the operation of differential unloading relief valve
Describe how this hydraulic circuit making use of a pressure switch replicates the function of an unloading valve.
Describe how this hydraulic circuit making use of a pressure switch replicates the function of an unloading valve.
Describe how this hydraulic circuit making use of a pressure switch that turns off the prime mover when pressure is in excess of the set value contributes towards efficient operation.
05.5: Counter Balance Valves
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/hydraulics/?p=160
NOTE: first 13 entries are REVIEW of pressure control valve family
List the 5 main types of pressure control valves. Draw their associated schematic symbols.
Identify the 5 main characteristics used to classify pressure control valves.
Describe the purpose of a pilot line. Describe the schematic symbol.
Identify pressure control valves that make use of internal pilot lines on their primary, or input, port.
Identify pressure control valves that make use of internal pilot lines on their secondary, or output, port.
Identify pressure control valves that make use of external pilot lines.
Identify pressure control valves that have a NC deactivated state.
Identify pressure control valves that have a NO deactivated state.
Identify pressure control valves that have a check valve bypass. Identify why a check valve bypass is necessary.
Identify pressure control valves that do not have a check valve bypass. Identify why a check valve bypass is not necessary.
Identify pressure control valves that have an internal drain. Identify why an external drain is not necessary.
Identify pressure control valves that have an external drain. Identify why an external drain is necessary. Describe the schematic symbol for an external drain.
Identify customary locations for the 5 main pressure control valves.
Describe a counterbalance valve using the 5 main characteristics used to classify pressure control valves.
Describe the basic operation of a counterbalance valve.
Compare the operation of these two hydraulic circuits when the laterally manipulated load is fully supported by some outside force.
Compare the operation of these two hydraulic circuits when the vertically manipulated load is influenced by some outside force like gravity.
Compare and contrast these circuits making use of counterbalance valves and meter out flow control circuits.
Describe the operation of this circuit making use of an internally piloted counterbalance valve. Comment on the maximum downwards force exerted by this system.
Describe the operation of this circuit making use of an externally piloted counterbalance valve used to lower a heaving mold, forming piece or platen. Comment on the behavior of this system during lowering and the maximum downwards force it is capable of generating.
Describe the operation of this circuit making use of an internally and externally piloted counterbalance valve used to lower a heaving mold, forming piece or platen. Comment on the behavior of this system during lowering and the maximum downwards force it is capable of generating.
Comment on observed behavior of hydraulic systems for different counterbalance valve set values and loads.
Compare and contrast the general behavior of internal, external, and internal and externally piloted counterbalance valves. | textbooks/workforce/Electronics_Technology/Hydraulics_and_Electrical_Control_of_Hydraulic_Systems_(Pytel)/5%3A_Pressure_Control/05.4%3A_Unloading_Valves.txt |
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/hydraulics/?p=202
Describe the behavior of this electrically controlled hydraulic circuit.
Discuss the influences of loss of power to magnetic proximity switch.
Discuss the influences of an errant metal object near the magnetic proximity switch.
06.1:1 Electrically Sequenced Hydraulic Cylinders
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/hydraulics/?p=205
Describe the operation of this manually sequenced clamp and bend hydraulic circuit. Discuss any disadvantages of this system.
Describe the operation of this clamp and bend hydraulic circuit making use of a single directional control valve. Discuss any disadvantages of this system.
Describe the operation of this multi actuator hydraulic circuit making use of a sequence valve on the cap end of the bend cylinder. Assume the set value of the sequence valve is 400psi and the main pressure relief valve is set to 800psi.
Describe the operation of this multi actuator hydraulic circuit making use of a sequence valve on the cap end of the bend cylinder and another sequence valve on the rod end of clamp cylinder.
Identify potential disadvantages of coordinating actuation sequence using solely pressure input.
Describe the operation of this electrically controlled clamp and bend hydraulic system.
Describe what would occur if the clamp cylinder ever lagged significantly behind the bend cylinder during retraction.
Describe the operation of this electrically sequenced clamp and bend hydraulic system.
Discuss any advantages exhibited by the above purely electrically sequenced clamp and bend system compared to those making use of hydraulic sequence valves.
06.1: Introduction to Electrically Controlled Systems
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/hydraulics/?p=171
List basic applications of electrically controlled systems.
Give examples of inputs, outputs, and internal components in an electrically controlled system
Give examples of potential faults in an electrically controlled system
Differentiate between control/pilot signal and power/primary signals
Describe the purpose of separating pilot and primary
Describe the purpose of a control transformer
Describe the similarities and differences between a contactor and a solenoid operated valve
Describe ladder logic diagrams and indicate the advantages of ladder logic
List the general rules of ladder logic
Differentiate between switches and sensors
Describe the purpose of a transducer
Differentiate between manual and mechanical/automatic switches and give examples of each
Describe span/hysteresis/override
Differentiate between hard wired relay based ladder logic and PLCs and discuss the advantages of PLCs
Describe a control relay
Describe the AND function
Describe the OR function
Describe the operation of this electrically controlled system.
Discuss general troubleshooting procedures for electrically controlled systems.
06.2: Control Relays
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/hydraulics/?p=174
Describe a control relay and identify its purpose in an electrically controlled system
Describe the similarities and differences between a contactor and a control relay
Describe the keyed base associated with an ice cube relay and identify advantages of using keyed bases.
Draw the NEMA schematic symbol for a control relay with a coil, two NO SPST contacts, and two NC SPST contacts
Draw the NEMA schematic symbol for a control relay with a coil and two SPDT C form/transfer contacts
Draw the IEC schematic symbol for a control relay with a coil and two SPDT C form/transfer contacts
Number the terminals of the above control relays
Describe a solenoid and discuss its function and purpose inside a control relay
Describe the components of a control relay and identify their purpose
Define and differentiate between rated voltage, pickup voltage, hold in voltage, and dropout voltage
Describe why a 120V AC coil cannot be used with 24V DC
Differentiate between inrush and sealed in current
Describe why a means of voltage spike suppression must be used for certain coils
Discuss points of inspection and maintenance procedures for control relays
Describe the purpose of bifurcated or split contacts in a control relay
Differentiate between make, break, and continuous current carrying capacity
Describe a solid state relay in general terms
Discuss the PLC and its relation to the control relay (comment at 25:40)
BONUS: Describe the behavior of this ladder logic diagram making use of a control relay and its associated contacts for the following sequence of actions:
both STOP and START in their deactivated state
operator presses and releases START
operator presses and releases STOP
06.3: Solenoid Operated Valves
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/hydraulics/?p=177
Describe a solenoid operated valve and identify its purpose in an electrically controlled system
Describe the similarities and differences between a solenoid operated valve and a contactor
Differentiate between the terms NO and NC as applied to electrical switches and valves
Draw the hydraulic schematic symbol for a spring offset, 2 position, four way, solenoid operated valve with a cross connect in the deactivated state and a straight through in the activated state
Draw the electrical schematic symbol for the coil of a solenoid operated valve
Describe a solenoid and discuss its function and purpose inside a solenoid operated valve
Describe the purpose of the drain port inside a solenoid operated hydraulic valve
Describe the purpose of a manual override for a solenoid operated valve and draw its schematic symbol
Differentiate between the applications of closed, tandem, float, and open center 3 position valves
Describe the problems associated with the simultaneous activation of both solenoids for a double solenoid valve and discuss the means of preventing this from occurring
Differentiate between electrically held and detented solenoid operated valves
Describe the components of a typical solenoid operated valve and identify their purpose
Define and differentiate between rated voltage, pickup voltage, hold in voltage, and dropout voltage
Describe why a 120V AC coil cannot be used with 24V DC
Differentiate between inrush and sealed in current
Describe why a means of voltage spike suppression must be used for certain coils
Discuss points of inspection and maintenance procedures for solenoid operated valves
Describe shift limit characteristics for solenoid operated valves
Define both “rated flow” and “maximum inlet pressure” for solenoid operated valves
Describe both the “pressure drop for different flow rates” and “operating limits” performance curve for solenoid operated valves
Describe leakage, fluid compatibility, and required filtration specifications for solenoid operated valves
Describe a variable solenoid operated valve and discuss its application for a hydraulic system
Describe a piggyback valve and discuss its application for a hydraulic system | textbooks/workforce/Electronics_Technology/Hydraulics_and_Electrical_Control_of_Hydraulic_Systems_(Pytel)/6%3A_Electrically_Controlled_Hydraulic_Systems/06.1%3A0_Single_Cycle_Reciprocation_with_Magnetic_Proximity_Switch.txt |
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/hydraulics/?p=179
Compare and contrast switches and sensors/transducers.
Discuss observed properties of closed and open switches with respect to resistance and current.
Define the terms pole and throw.
Draw the schematic symbol for the following switches: SPST, SPDT, SPTT-CO, DPST, DPDT, 3PST
Define the term electrical isolation.
Define the term actuation and differentiate between manually and mechanically/automatically actuated switches.
Define making and breaking.
Differentiate between the deactivated state and activated state of a switch.
Identify in which state switches are illustrated in schematics.
Differentiate between the deenergized state and energized state of a load.
Differentiate between NC and NO switches in their deactivated and activated states. Identify resistance and current carrying ability in both states.
Describe advantages of a double break switch over a single break switch.
Define a mechanical interlock.
Differentiate between momentary and maintained contact switches.
Draw the schematic symbol for a maintained contact ESTOP button.
Draw the schematic symbol for a momentary contact break-make pushbutton package consisting of a mechanically interlocked set of NC and NO contacts.
Identify the purpose of an auxiliary contact block.
Draw the schematic symbol for a maintained contact 3 position selector switch with two associated contacts A and B. Assume contact A is closed in position 1, both contacts are open in position 2, contact B is closed in position 3. Draw the target table/contact chart illustrating this functionality.
Draw the schematic symbol for a drum or cam switch used to reverse the rotational direction of an industrial 3 phase AC motor. Draw the target table/contact chart illustrating this functionality.
Draw the ladder logic representation of a limit switch consisting of a mechanically interlocked pair of NC and NO contacts. Draw the hydraulic schematic representation of a limit switch.
Describe the concept of switches being held in their activated state using both the gravity and arrow convention. Draw examples of each. Identify the preferred method.
Draw the schematic symbol for a temperature switch consisting of a mechanically interlocked pair of NC and NO contacts.
Draw the ladder logic representation of a pressure switch consisting of a mechanically interlocked pair of NC and NO contacts. Draw the hydraulic schematic representation of a pressure switch.
Differentiate between the set and reset value of a pressure switch. Identify why this is a desirable trait.
Draw the ladder logic representation of a float switch consisting of a mechanically interlocked pair of NC and NO contacts.
Draw the ladder logic representation of a rotational speed (plugging/anti-plugging) switch consisting of a mechanically interlocked pair of NC and NO contacts.
Differentiate between electromechanical and solid state switches, give examples of each.
Draw the ladder logic representation of a proximity switch consisting of a SPDT transfer contact. Draw the hydraulic schematic representation of a proximity switch.
Identify the advantages and disadvantages of proximity switches compared to limit switches.
Differentiate between inductive and capacitive proximity switches.
Define the terms operating point, release point, and hysteresis with respect to a proximity switch.
Draw the ladder logic representation of a photoelectric switch consisting of a SPDT transfer contact. Draw the hydraulic schematic representation of a photoelectric switch.
Differentiate between through beam scanners, retroreflective scanners, and diffuse scanners. Identify when a polarized retroreflective scanner would be used. | textbooks/workforce/Electronics_Technology/Hydraulics_and_Electrical_Control_of_Hydraulic_Systems_(Pytel)/6%3A_Electrically_Controlled_Hydraulic_Systems/06.4%3A_Switches_in_Electrically_Controlled_Systems.txt |
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/hydraulics/?p=181
Describe ladder logic diagrams and indicate the advantages of ladder logic
Differentiate between control/pilot signal and power/primary signals
Describe the purpose of separating pilot and primary
List the 11 basic rules of ladder logic as discussed in this lecture
Describe the behavior of this system for all possible combinations of input conditions.
Describe the behavior of this system for all possible combinations of input conditions.
Describe the behavior of this system for all possible combinations of input conditions.
Describe the behavior of this electrically controlled hydraulic system. Define the purpose of the holding circuit.
Describe the behavior of this electrically controlled hydraulic system incorporating a limit switch.
Compare and contrast hard wired relay based ladder logic with a programmable logic controller.
06.6: Alarm Circuit
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/hydraulics/?p=188
Discuss the significance of contacts being held in their activated state by a deenergized system.
Describe the behavior of this alarm system.
Describe the behavior of the above circuit if a NO pressure switch and a NO temperature switch are placed in parallel with the NC-HO FS1.
Describe the behavior of the above circuit if the NC-HO FS1 at the top of the tank is replaced with a NO FS1 at the bottom of a tank.
06.7: 2 and 3 Wire Control Circuits for Fluid Power Systems
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/hydraulics/?p=191
Describe a 2 wire control circuit.
Describe a 3 wire control circuit.
Describe the behavior of this 2 wire control circuit.
Describe the behavior of a 2 wire control circuit if it ever experienced sudden loss and restoration of pilot or primary power.
Describe the behavior of this 3 wire control circuit.
Describe the behavior of a 3 wire control circuit if it ever experienced sudden loss and restoration of pilot or primary power.
Differentiate between low or no voltage release circuits and low or no voltage protection circuits
Comment on the utility of lock out and tag out procedures.
06.8: Multiple Push Button Stations
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/hydraulics/?p=195
Identify the advantages of multiple push button stations.
Generalize the placement of input devices intended to stop the process and devices intended to start the process.
Describe the behavior of this electrically controlled hydraulic system making use of multiple pushbutton stations.
Comment on the observed behavior of a system making use of multiple push button stations if any one of the ESTOPs was accidentally triggered.
06.9: Single Cycle Reciprocation with Limit Switch
A YouTube element has been excluded from this version of the text. You can view it online here: https://openoregon.pressbooks.pub/hydraulics/?p=199
Define a single cycle reciprocation action.
Describe the behavior of this electrically controlled hydraulic circuit.
Discuss the influences of inadvertent opens at various points in ladder logic diagram.
Discuss the influences of the loss of primary hydraulic power.
Comment on the influences of an improperly set pressure relief valve.
Discuss the influences of an activated ESTOP.
Discuss the influences of a limit switch inadvertently triggered by some errant object.
Discuss the influences of an improperly positioned limit switch that fails to activate. | textbooks/workforce/Electronics_Technology/Hydraulics_and_Electrical_Control_of_Hydraulic_Systems_(Pytel)/6%3A_Electrically_Controlled_Hydraulic_Systems/06.5%3A_Basic_Ladder_Logic.txt |
Learning Objectives
• Demonstrate the use of the metric and imperial/U.S. measuring systems
• Convert and adjust measurements, recipes, and formulas
01: Trade Math
Canadian cooks should feel comfortable working in three different measurement systems. Two of these systems (U.S. and imperial) are closely related, while the third (S.I., more commonly called metric) is different from the other two.
Although the metric system was introduced in Canada a number of years ago, the food industry and home cooks still rely heavily on equipment and cookbooks imported from the United States. In addition, because we used imperial measurements in Canada for the sale of liquids, some industry recipes will call for imperial measurements rather than U.S. liquid measurements.
The imperial and U.S. measuring systems evolved out of the system used in Europe prior to the 20th century. Although both the imperial and U.S. systems use the same terminology, there are slight differences in actual measurements that you must account for, particularly with volume.
The easiest way to work with the three systems is to have different sets of measuring devices: one for the metric system, one for the imperial system, and one for the U.S. system. Alternatively, you could have one set of devices that have measurements for all three systems indicated. U.S. measuring instruments can be used with slight adjustments for imperial measuring.
It is not good practice to use two systems of measurement when preparing a recipe. Working between two systems of measurement in a recipe may result in inaccuracies that could affect the final product’s taste, yield, consistency, and appearance. To ensure a consistent and successful result, a good practice is to convert the recipe into one standard system of measurement.
The S.I. (Metric) System: Types, Units, and Symbols
All measuring systems have basic units for length, mass (weight), capacity (volume), and temperature. The basic units for the metric system are shown in Table 1.
Table 1: Basic metric units
Type of Measurement Unit Symbol
length (distance) metre m
mass (weight) gram g
capacity (volume) litre L
temperature degrees Celsius °C
Note that the abbreviation or symbol of the unit is not followed by a period and that all the abbreviations are lowercase letters except for litre which is usually a capital L.
In the metric system, the basic units are turned into larger or smaller measurements by using a prefix that carries a specific meaning as shown in Table 2. The most commonly used prefixes are kilo (k), centi (c), and milli (m).
Table 2: Metric prefixes
Prefix Symbol Meaning
kilo k 1000
hecto h 100
deca da 10
deci d 1/10 or 0.1
centi c 1/100 or 0.01
milli m 1/1000 or 0.001
When you read a measurement in the metric system, it is fairly easy to translate the measurement into a number of the basic units. For example, 5 kg (five kilograms) is the same as 5 × 1000 (the meaning of kilo) grams or 5000 grams. Or 2 mL (two millilitres) is the same as 2 × 0.001 (the meaning of milli) litres or 0.002 litres. This process is discussed further in the section on converting below.
The most commonly used measurements in commercial kitchens are mass (weight), capacity (volume), and temperature.
Units of Length (Distance)
The basic unit of length or distance in the metric system is the metre. The most frequently used units of length used in the Canadian food industry are the centimetre and millimetre. The units of length in the metric system are shown in Table 3.
Table 3: Metric units of length
Unit Abbreviation Length (Distance)
kilometre km 1000 meter
hectometre hm 100 metres
decametre dam 10 metres
metre m 1 metre
decimetre dm 0.1 metres
centimetre cm 0.01 metres
millimetre mm 0.001 metres
Units of Mass (Weight)
The basic unit of mass or weight in the metric system is the gram. The most frequently used units of mass or weight used in the Canadian food industry are the gram and kilogram. The units of mass in the metric system are shown in Table 4.
Table 4: Metric units of mass (weight)
Unit Abbreviation Mass (Weight)
tonne t 1000 kilograms
kilogram kg 1000 grams
hectogram hg 100 grams
decagram dag 10 grams
gram g 1 gram
decigram dg 0.1 g
centigram cg 0.01 g
milligram mg 0.001
Note: Certain metric terminology is not regularly used for ease of production and service. The average cook or chef will not remember how many grams there are in a hecto-, deca-, deci-, or centigram. It is much more practical to write and read 100 grams in a recipe than 1 hectogram.
Units of Capacity (Volume)
The basic unit of volume or capacity is the litre. The most commonly used units in cooking are the litre and the millilitre. The units of volume in the metric system are shown in Table 5.
Table 5: Metric units of volume
Unit Abbreviation Volume
kilolitre kL 1000 L
hectolitre hL 100 L
decalitre daL 10 L
litre L 1 L
decilitre dL 0.1 L
centilitre cL 0.01 L
millilitre mL 0.001 L
Occasionally, you will encounter a unit of volume called cubic measurement (sometimes used to express the volume of solids or the capacity of containers), and the units will be expressed as “cc” or cm3 (cubic centimetre). Cubic centimetres are the same as millilitres. That is, 1 cc = 1 cm3 = 1 mL
In the metric system, 1 mL (cc) of water weighs 1 gram. We will explore this later when discussing the difference between measuring by weight and by volume.
1.02: Temperature
The metric units for temperature are degrees Celsius (°C). There are no other units used. Temperature is one area where you may find it necessary to convert from Celsius to Fahrenheit and vice versa, as you probably do not have two ovens or stoves at your disposal. However, many modern stoves and ovens, as well as most thermometers, have both Celsius and Fahrenheit temperatures marked on their controls.
Note: There are many “apps” available for converting measurements. These can easily be downloaded onto a smartphone or tablet and used in the kitchen.
1.03: Converting Within the Metric System
To convert from one unit to another within the metric system usually means moving a decimal point. If you can remember what the prefixes mean, you can convert within the metric system relatively easily by simply multiplying or dividing the number by the value of the prefix.
The most common metric measurements used in the food service industry are kilograms, grams, litres, and millilitres.
Examples of How to Convert Between Measurements
Example 1
Convert 26.75 kg to g.
First, write the question with the meaning of the prefix inserted. In this example, k is the prefix, and k means 1000, so:
26.75 kg = 26.75 × (1000) g = 26 750 g
Notice that there is no comma used in the answer 26 750 g. In the metric system, large numbers are separated every three digits by a space, not a comma.
Example 2
Convert 0.2 L to mL.
Again, write the question with the meaning of the prefix inserted. In this example, m is the prefix, and m means 0.001, so:
0.2 L = _____ (0.001) L
To find the blank (the value of the millilitres), divide the left-hand number by the right-hand number.
0.2 L ÷ 0.001 L = 200
This means 0.2 L = 200 mL.
Notice that there is a zero (0) before (to the left of) the decimal point. When writing decimal numbers that are smaller than 1 in the metric system, it is customary to place a zero to the left of the decimal point. Thus .6 in the metric system is written 0.6.
If you are working with two prefixes, you can convert in much the same way as above.
Example 3
Find the number of dL in 12.2 mL.
The prefixes are d, which means 0.1, and m, which means 0.001. Insert the values of the prefixes into the conversion.
_____ dL = 12.2 mL
_____ (0.1) L = 12.2 (0.001) L
_____ (0.1) L = 0.0122 L
To find the value of the blank, divide the right-hand number by the left-hand number.
0.0122 L ÷ 0.1 L = 0.122
This means that 12.2 mL = 0.122 dL. | textbooks/workforce/Food_Production_Service_and_Culinary_Arts/Basic_Kitchen_and_Food_Service_Management_(BC_Campus)/01%3A_Trade_Math/1.01%3A_Units_of_Measurement.txt |
Canada used the U.S. and imperial systems of measurement until 1971 when the S.I. or metric system was declared the official measuring system for Canada, which is now in use in most of the world, with the United States being the major exception. However, “declaring” and “truly adopting” are not always the same.
Because of Canada’s strong ties to the United States, a lot of our food products come from across the border, and many Canadian producers also sell in the U.S. market. This is one of the main reasons Canadians need to know how to work in both systems. Most Canadian packages include both Canadian and U.S. or imperial measurements on the label, and many suppliers still quote prices in cost per pound instead of cost per kilogram.
The most commonly used units of measurement in the U.S. and imperial systems are shown in Table 6.
Table 6: U.S. and imperial units of measurement
Type of Measurement Unit Abbreviation
Weight Pound lb. or #
Weight Ounce oz.
Volume Gallon gal.
Volume Quart qt.
Volume Pint pt.
Volume Cup c.
Volume Fluid ounce fl.oz. or oz.
Volume Tablespoon Tbsp. or tbsp.
Volume Teaspoon tsp.
Length Mile m.
Length Yard yd.
Length Foot ft. or ′
Length Inch in. or ″
Note: There is sometimes confusion about the symbol #. When # is used in front of a number, such as in #10, the # is read as the word number. Thus, #10 is read as number 10. When the # follows a number, the # is read as pounds. Thus, 10# is read as 10 pounds.
Differences between the U.S. and Imperial Systems
The only difference between the imperial system and the U.S. system is in volume measurements. Not only are the number of ounces in pints, quarts, and gallons all larger in the imperial system, the size of one fluid ounce is also different, as shown in the table in Table 7.
Table 7: Differences between U.S. and imperial volume measurements
Unit of Measurement Imperial System Metric Equivalent U.S. System Metric Equivalent
1 ounce 1 (fluid) oz. 28.41 mL 1 (fluid) oz. 29.57 mL
1 gill 5 (fluid) oz. 142.07 mL Not commonly used
1 cup Not commonly used 8 (fluid) oz. 236.59 mL
1 pint 20 (fluid) oz. 568.26 mL 16 (fluid) oz. 473.18 mL
1 quart 40 (fluid) oz. 1.137 L 32 (fluid) oz. 946.36 mL
1 gallon 160 (fluid) oz. 4.546 L 128 (fluid) oz. 3.785 L
Where you will notice this most is with any liquid products manufactured in Canada; these products will show the metric conversion using imperial measurement, but any products originating in the United States will show the conversion using U.S. measurements. For example, if you compare 12 fl. oz. bottles or cans of soft drinks or beer, you will see that American brands contain 355 mL (12 fl. oz. U.S.) and Canadian brands contain 341 mL (12 fl. oz. imperial).
If you are using a recipe written in cups and ounces, always verify the source of your recipe to determine if it has been written using the U.S. or imperial system of measurement. The difference in volume measurements can be quite noticeable when producing large quantities.
If the recipe is from the United States, use U.S. measurements for the conversion, if the recipe originated in the United Kingdom, Australia, or any other country that was once part of the British Empire, use imperial for the conversion.
Converting between Units in the Imperial and U.S. Systems
On occasion, you may need to convert between the various units of volume and between units of volume and units of weight in the U.S. system. To do this, you must know the equivalents for each of the units as shown in Table 8.
Table 8: Equivalent measures within the U.S. and Imperial system
Types of Measurement Conversion
Weight 1 pound = 16 ounces
Volume (U.S.) 1 gallon = 4 quarts or 128 (fluid) ounces
Volume (U.S.) 1 quart = 2 pints or 4 cups or 32 (fluid) ounces
Volume (U.S.) 1 pint = 2 cups or 16 (fluid) ounces
Volume (U.S.) 1 cup= 8 (fluid) ounces or 16 tablespoons
Volume (U.S.) 1 (fluid) ounce = 2 tablespoons
Volume (U.S.) 1 tablespoon = 3 teaspoons
Volume (imperial) 1 gallon = 4 quarts or 160 (fluid) ounces
Volume (imperial) 1 quart = 2 pints or 40 (fluid) ounces
Volume (imperial) 1 pint = 20 (fluid) ounces
Volume (imperial) 1 gill = 5 (fluid) ounces or 10 tablespoons
Volume (imperial) 1 (fluid) ounce = 2 tablespoons
Volume (imperial) 1 tablespoon = 3 teaspoons
Length 1 mile = 1760 yards
Length 1 yard = 3 feet
Length 1 foot = 12 inches
Note: One fluid ounce (usually called, simply, ounce) of water weighs approximately one ounce.
To convert from one unit to another, you either divide or multiply, depending on whether you are converting a smaller unit to a larger one, or a larger unit or to a smaller one.
Converting Smaller to Larger Units
To convert from a smaller to a larger unit, you need to divide. For example, to convert 6 tsp. to tablespoons, divide the 6 by the number of teaspoons in one tablespoon, which is 3 (see Table 8).
6 tsp = __ tbsp.
6 ÷ 3 = 2
6 tsp. = 2 tbsp.
To convert ounces to cups, you need to divide by 8 since there are 8 oz. in 1 cup. For example, if you need to convert 24 oz. to cups, you have to divide 24 by 8.
24 oz. = __ cups
24 ÷ 8 = 3
24 oz. = 3 cups
Converting Larger to Smaller Units
To change larger units to smaller, you have to multiply the larger unit by the number of smaller units in that unit. For example, to convert quarts to pints, you have to multiply the number of quarts by 2 because there are 2 pts. in 1 qt. Therefore, to convert 6 qts. to pints you need to multiply:
6 qts. = __ pts.
6 × 2 = 12
6 qts. = 12 pts.
To convert cups to tablespoons, you need to multiply by 16 since there are 16 tbsp. in 1 cup.
3/4 cup = __ tbsp.
16 × 3/4 = 12
3/4 cup = 12 tbsp.
Converting between Metric and Imperial/U.S. Measurement Systems
You can convert between metric and imperial or U.S. measurements with straightforward multiplication or division if you know the conversion ratios. Table 9.1 and 9.2 are a good reference, but there are also many online converters or apps available to make this task easier.
Table 9.1: Convert from metric to imperial/U.S.
When you know Divide by To get
millilitres 4.93 teaspoons
millilitres 14.79 tablespoons
millilitres 28.41 fluid ounces (imperial)
millilitres 29.57 fluid ounces (U.S.)
millilitres 236.59 cups
litres 0.236 cups
millilitres 473.18 pints (U.S.)
litres 0.473 pints (U.S.)
millilitres 568.26 pints (imperial)
litres 0.568 pints (imperial)
millilitres 946.36 quarts (U.S.)
litres 0.946 quarts (U.S.)
millilitres 1137 quarts (imperial)
litres 1.137 quarts (imperial)
litres 3.785 gallons (U.S.)
litres 4.546 gallons (imperial)
grams 28.35 ounces
grams 454 pounds
kilograms 0.454 pounds
centimetres 2.54 inches
millimetres 25.4 inches
Celsius (Centigrade) multiply by 1.8 and add 32 Fahrenheit
Table 9.2: Convert from imperial/U.S. to metric
When you know Multiply by To get
teaspoons 4.93 millilitres
tablespoons 14.79 millilitres
fluid ounces (imperial) 28.41 millilitres
fluid ounces (U.S.) 29.57 millilitres
cups 236.59 millilitres
cups 0.236 litres
pints (U.S.) 473.18 millilitres
pints (U.S.) 0.473 litres
pints (imperial) 568.26 millilitres
pints (imperial) 0.568 litres
quarts (U.S.) 946.36 millilitres
quarts (U.S.) 0.946 litres
quarts (imperial) 1137 millilitres
quarts (imperial) 1.137 litres
gallons (U.S.) 3.785 litres
gallons (imperial) 4.546 litres
ounces 28.35 grams
pounds 454 grams
pounds 0.454 kilograms
inches 2.54 centimetres
inches 25.4 millimetres
Fahrenheit subtract 32 and divide by 1.8 Celsius (Centigrade)
Table 10 lists the most common U.S. measurements and metric units of measure, and their equivalents used in professional kitchens. Table 11 presents the conversion factors.
Table 10: Common Metric and U.S. conversions
Measurement type Unit Equivalent
Length 1 inch 25.4 millimetres
Length 1 centimetre 0.39 inches
Length 1 metre 39.4 inches
Volume 1 fluid ounce (U.S.) 29.57 millilitres
Volume 1 cup 237 millilitres
Volume 1 quart 946 millilitres
Volume 1 millilitre 0.034 fluid ounces
Volume 1 litre 33.8 fluid ounces
Weight 1 ounce 28.35 grams
Weight 1 pound 454 grams
Weight 1 gram 0.035 ounce
Weight 1 kilogram 2.205 pounds
Table 11: Metric and U.S. Equivalents and Conversions
Measurement type To convert Multiply by Result
Length Inches to millimeters 25.4 1 inch = 25.4 mm
Length Inches to centimetres 2.54 1 inch = 2.54 cm
Length Millimetres to inches 0.03937 1 mm = 0.03937 in.
Length Centimetres to inches 0.3937 1 cm = 0.3937 in.
Length Metres to inches 39.3701 1m = 39.37 in.
Volume Quarts to litres 0.946 1 qt. = 0.946 L
Volume Litres to fluid ounces (U.S.) 33.8 1 L = 33.8 oz.
Volume Quarts to millilitres 946 1 qt. = 946 mL
Volume Millilitres to ounces 0.0338 1 mL = 0.0338 oz.
Volume Litres to quarts 1.05625 1 L = 1.05625 qt.
Weight Ounces to grams 28.35 1 oz. = 28.35 g
Weight Grams to ounces 0.03527 1 g = 0.03527 oz.
Weight Kilograms to pounds 2.2046 1 kg = 2.2046 lb.
Soft Conversions
Many times, cooks will use what are called “soft conversions” rather than exact conversions, especially in small batch recipes where a slight variation can be tolerated, as it is often difficult to measure very fine quantities using liquid measures. This is a shortcut that can be used if you are faced with only a set of metric measuring tools and a U.S. recipe (or vice versa). Table 12 lists the common soft conversions.
Table 12: Soft conversions
Metric U.S. Measurements
1 millilitre 1/4 teaspoon
2 millilitres 1/2 teaspoon
5 millilitres 1 teaspoon
15 millilitres 1 tablespoon
30 millilitres 1 fluid ounce
250 millilitres 1 cup
500 millilitres 1 pint
1 litre 1 quart
4 litres 1 gallon
Types of Measurements Used in the Kitchen
There are three types of measurements used to measure ingredients and to serve portions in the restaurant trade. Measurement can be by volume, by weight, or by count.
Recipes may have all three types of measurement. A recipe may call for 3 eggs (measurement by count), 250 mL of milk (measurement by volume), and 0.5 kg of cheese (measurement by weight).
There are formal and informal rules governing which type of measurement should be used. There are also specific procedures to ensure that the measuring is done accurately and consistently.
Number or Count
Number measurement is only used when an accurate measurement is not critical and the items to be used are understood to be close in size.
For example, “3 eggs” is a common measurement called for in recipes, not just because 3 is easy to count but also because eggs are graded to specific sizes. Most recipes call for large eggs unless stated otherwise.
Numbers are also used if the final product is countable. For example, 24 premade tart shells would be called for if the final product is to be 24 filled tart shells.
Volume
Volume measurement is usually used with liquids or fluids because such items are awkward to weigh. It is also used for dry ingredients in home cooking, but it is less often used for dry measurement in the industry.
Volume is often the measure used when portioning sizes of finished product. For example, portion scoops are used to dole out vegetables, potato salad, and sandwich fillings to keep serving size consistent. Ladles of an exact size are used to portion out soups and sauces.
Often scoops and ladles used for portioning are sized by number. On a scoop, such a number refers to the number of full scoops needed to fill a volume of one litre or one quart. Ladles are sized in millilitres or ounces.
Weight
Weight is the most accurate way to measure ingredients or portions. When proportions of ingredients are critical, their measurements are always given in weights. This is particularly true in baking where it is common to list all ingredients by weight, including eggs (which, as mentioned earlier, in almost all other applications are called for by count). Whether measuring solids or liquids, measuring by weight is more reliable and consistent.
Weighing is a bit more time consuming and requires the use of scales, but it pays off in accuracy. Digital portion scales are most commonly used in industry and come in various sizes to measure weights up to 5 kg (11 lbs.). This is adequate for most recipes, although larger operations may require scales with a larger capacity.
The reason weight is more accurate than volume is because it takes into account factors such as density, moisture, and temperature that can have an effect on the volume of ingredients. For example, 250 mL (1 cup) of brown sugar (measured by volume) could change drastically depending on whether it is loosely or tightly packed in the vessel. On the other hand, 500 grams (17.63 oz.) of brown sugar, will always be 500 grams (17.63 oz.).
Even flour, which one might think is very consistent, will vary from location to location, and the result will mean an adjustment in the amount of liquid needed to get the same consistency when mixed with a given volume.
Another common mistake is interchanging between volume and weight. The only ingredient that will have the same volume and weight consistently is water: 1 L of water = 1 kg of water.
There is no other ingredient that can be measured interchangeably because of gravity and the density of an item. Every ingredient has a different density and different gravitational weight, which will also change according to location. This is called specific gravity. Water has a specific gravity of 1.0. Liquids that are lighter than water (such as oils that float on water) have a specific gravity of less than 1.0. Those that are heavier than water and will sink, such as molasses, have a specific gravity greater than 1.0. Unless you are measuring water, remember not to use a volume measure for a weight measure, and vice versa.
Example 4
1 L water = 1 kg water
1 L water + 1 L canola oil = 2 L of water and oil mixture (volume)
1 L water + 1 L canola oil = 1.92 kg (weight)
In order to convert your existing recipes that only call for volume measurement to weight, you will need to measure each ingredient by volume, weigh it, and then record the amount in your recipe. There are also tools that can help with this conversion.
• Aqua-calc: Online Food Calculator is an online calculator has an extensive database of foods and can convert from volume to weight in both the metric and U.S. measuring systems.
• Lee Valley Kitchen Calculator is a conversion calculator has the capacity to convert between weight and volume. It comes with an attached list of ingredients and their specific gravitational weights. It is, however, a list of only the most common ingredients and will not likely cover everything that a commercial kitchen uses. | textbooks/workforce/Food_Production_Service_and_Culinary_Arts/Basic_Kitchen_and_Food_Service_Management_(BC_Campus)/01%3A_Trade_Math/1.04%3A_Imperial_and_U.S._Systems_of_Measurement.txt |
Recipes often need to be adjusted to meet the needs of different situations. The most common reason to adjust recipes is to change the number of individual portions that the recipe produces. For example, a standard recipe might be written to prepare 25 portions. If a situation arises where 60 portions of the item are needed, the recipe must be properly adjusted.
Other reasons to adjust recipes include changing portion sizes (which may mean changing the batch size of the recipe) and better utilizing available preparation equipment (for example, you need to divide a recipe to make two half batches due to a lack of oven space).
Conversion Factor Method
The most common way to adjust recipes is to use the conversion factor method. This requires only two steps: finding a conversion factor and multiplying the ingredients in the original recipe by that factor.
Finding Conversion Factors
To find the appropriate conversion factor to adjust a recipe, follow these steps:
1. Note the yield of the recipe that is to be adjusted. The number of portions is usually included at the top of the recipe (or formulation) or at the bottom of the recipe. This is the information that you HAVE.
2. Decide what yield is required. This is the information you NEED.
3. Obtain the conversion factor by dividing the required yield (from Step 2) by the old yield (from Step 1). That is, conversion factor = (required yield)/(recipe yield) or conversion factor = what you NEED ÷ what you HAVE.
Example 5
To find the conversion factor needed to adjust a recipe that produces 25 portions to produce 60 portions, these are steps you would take:
1. Recipe yield = 25 portions
2. Required yield = 60 portions
3. Conversion factor
1. = (required yield) ÷ (recipe yield)
2. = 60 portions ÷ 25 portions
3. = 2.4
If the number of portions and the size of each portion change, you will have to find a conversion factor using a similar approach:
1. Determine the total yield of the recipe by multiplying the number of portions and the size of each portion.
2. Determine the required yield of the recipe by multiplying the new number of portions and the new size of each portion.
3. Find the conversion factor by dividing the required yield (Step 2) by the recipe yield (Step 1). That is, conversion factor = (required yield)/(recipe yield).
Example 6
For example, to find the conversion factor needed to change a recipe that produces 20 portions with each portion weighing 150 g into a recipe that produces 60 portions with each portion containing 120 g, these are the steps you would take:
1. Old yield of recipe = 20 portions × 150 g per portion = 3000 g
2. Required yield of recipe = 40 portions × 120 g per portion = 4800 g
3. Conversion factor
1. = required yield ÷ old yield
2. = 4800 ÷ 3000
3. = 1.6
Key Takeaway
To ensure you are finding the conversion factor properly, remember that if you are increasing your amounts, the conversion factor will be greater than 1. If you are reducing your amounts, the factor will be less than 1.
Adjusting Recipes Using Conversion Factors
Now that you have the conversion factor, you can use it to adjust all the ingredients in the recipe. The procedure is to multiply the amount of each ingredient in the original recipe by the conversion factor. Before you begin, there is an important first step:
Before converting a recipe, express the original ingredients by weight whenever possible.
Converting to weight is particularly important for dry ingredients. Most recipes in commercial kitchens express the ingredients by weight, while most recipes intended for home cooks express the ingredients by volume. If the amounts of some ingredients are too small to weigh (such as spices and seasonings), they may be left as volume measures. Liquid ingredients also are sometimes left as volume measures because it is easier to measure a litre of liquid than it is to weigh it. However, a major exception is measuring liquids with a high sugar content, such as honey and syrup; these should always be measured by weight, not volume.
Converting from volume to weight can be a bit tricky and may require the use of tables that provide the approximate weight of different volume measures of commonly used recipe ingredients. Once you have all ingredients in weight, you can then multiply by the conversion factor to adjust the recipe.
When using U.S. or imperial recipes, often you must change the quantities of the original recipe into smaller units. For example, pounds may need to be expressed as ounces, and cups, pints, quarts, and gallons must be converted into fluid ounces.
Converting a U.S. Measuring System Recipe
The following example will show the basic procedure for adjusting a recipe using U.S. measurements.
Example 7
Adjust a standard formulation (Table 13) designed to produce 75 biscuits to have a new yield of 300 biscuits.
Table 13: Table of ingredients for conversion recipe in U.S. system
Ingredient Amount
Flour 3¼ lbs.
Baking Powder 4 oz.
Salt 1 oz.
Shortening 1 lb.
Milk 6 cups
Solution
1. Find the conversion factor.
1. conversion factor = new yield/old yield
2. = 300 biscuits ÷ 75 biscuits
3. = 4
2. Multiply the ingredients by the conversion factor. This process is shown in Table 14.
Table 14: Table of ingredients for recipe adjusted in U.S. system
Ingredient Original Amount (U.S) Conversion factor New Ingredient Amount
Flour 3¼ lbs. 4 13 lbs.
Baking powder 4 oz. 4 16 oz. (= 1 lb.)
Salt 1 oz. 4 4 oz.
Shortening 1 lb. 4 4 lbs.
Milk 6 cups 4 24 cups (= 6 qt. or 1½ gal.)
Converting an Imperial Measuring System Recipe
The process for adjusting an imperial measure recipe is identical to the method outlined above. However, care must be taken with liquids as the number of ounces in an imperial pint, quart, and gallon is different from the number of ounces in a U.S. pint, quart, and gallon. (If you find this confusing, refer back to Table 7 and the discussion on imperial and U.S. measurements.)
Converting a Metric Recipe
The process of adjusting metric recipes is the same as outlined above. The advantage of the metric system becomes evident when adjusting recipes, which is easier with the metric system than it is with the U.S. or imperial system. The relationship between a gram and a kilogram (1000 g = 1 kg) is easier to remember than the relationship between an ounce and a pound or a teaspoon and a cup.
Example 8
Adjust a standard formulation (Table 15) designed to produce 75 biscuits to have a new yield of 150 biscuits.
Table 15: Table of ingredients for conversion recipe in metric system
Ingredient Amount
Flour 1.75 kg
Baking powder 50 g
Salt 25 g
Shortening 450 g
Milk 1.25 L
Solution
1. Find the conversion factor.
1. conversion factor = new yield/old yield
2. = 150 biscuits÷75 biscuits
3. = 2
2. Multiply the ingredients by the conversion factor. This process is shown in Table 16.
Table 16: Table of ingredients for recipe adjusted in metric system
Ingredient Amount Conversion Factor New Amount
Flour 1.75 kg 2 3.5 kg
Baking powder 50 g 2 100 g
Salt 25 g 2 50 g
Shortening 450 g 2 900 g
Milk 1.25 L 2 2.5 L
Cautions when Converting Recipes
Although recipe conversions are done all the time, several problems can occur. Some of these include the following:
• Substantially increasing the yield of small home cook recipes can be problematic as all the ingredients are usually given in volume measure, which can be inaccurate, and increasing the amounts dramatically magnifies this problem.
• Spices and seasonings must be increased with caution as doubling or tripling the amount to satisfy a conversion factor can have negative consequences. If possible, it is best to under-season and then adjust just before serving.
• Cooking and mixing times can be affected by recipe adjustment if the equipment used to cook or mix is different from the equipment used in the original recipe.
The fine adjustments that have to be made when converting a recipe can only be learned from experience, as there are no hard and fast rules. Generally, if you have recipes that you use often, convert them, test them, and then keep copies of the recipes adjusted for different yields, as shown in Table 17.
Recipes for Different Yields of Cheese Puffs
Table 17.1: Cheese Puffs, Yield 30
Ingredient Amount
Butter 90 g
Milk 135 mL
Water 135 mL
Salt 5 mL
Sifted flour 150 g
Large eggs 3
Grated cheese 75 g
Cracked pepper To taste
Table 17.2: Cheese Puffs, Yield 60
Ingredient Amount
Butter 180 g
Milk 270 mL
Water 270 mL
Salt 10 mL
Sifted flour 300 g
Large eggs 6
Grated cheese 150 g
Cracked pepper To taste
Table 17.3: Cheese Puffs, Yield 90
Ingredient Amount
Butter 270 g
Milk 405 mL
Water 405 mL
Salt 15 mL
Sifted flour 450 g
Large eggs 9
Grated cheese 225 g
Cracked pepper To taste
Table 17.4: Cheese Puffs, Yield 120
Ingredient Amount
Butter 360 g
Milk 540 mL
Water 540 mL
Salt 20 mL
Sifted flour 600 g
Large eggs 12
Grated cheese 300 g
Cracked pepper To taste
Baker’s Percentage
Many professional bread and pastry formulas are given in what is called baker’s percentage. Baker’s percentage gives the weights of each ingredient relative to the amount of flour (Table 18). This makes it very easy to calculate an exact amount of dough for any quantity.
Table 18: A formula stated in baker’s percentage
Ingredient % Total Unit
Flour 100.0% 15 kg
Water 62.0% 9.3 kg
Salt 2.0% 0.3 kg
Sugar 3.0% 0.45 kg
Shortening 1.5% 0.225 kg
Yeast 2.5% 0.375 kg
Total weight: 171.0% 25.65 kg
To convert a formula using baker’s percentage, there are a few options:
If you know the percentages of the ingredients and amount of flour, you can calculate the other ingredients by multiplying the percentage by the amount of flour to determine the quantities. Table 19 shows that process for 20 kg flour.
Table 19: Baker’s percentage formula adjusted for 20 kg flour
Ingredient % Total Unit
Flour 100.0% 20 kg
Water 62.0% 12.4 kg
Salt 2.0% 0.4 kg
Sugar 3.0% 0.6 kg
Shortening 1.5% 0.3 kg
Yeast 2.5% 0.5 kg
Total weight: 171.0% 34.20 kg
If you know the ingredient amounts, you can find the percentage by dividing the weight of each ingredient by the weight of the flour. Remember, flour is always 100%. For example, the percentage of water is 6.2 ÷ 10 = 0.62 × 100 or 62%. Table 20 shows that process for 10 kg of flour.
Table 20: Baker’s percentages given for known quantities of ingredients
Ingredient % Total Unit
Flour 100.0% 10 kg
Water 62.0% 6.2 kg
Salt 2.0% 0.2 kg
Sugar 3.0% 0.3 kg
Shortening 1.5% 0.15 kg
Yeast 2.5% 0.25 kg
Example 9
Use baker’s percentage to find ingredient weights when given the total dough weight.
For instance, you want to make 50 loaves at 500 g each. The weight is 50 × 0.5 kg = 25 kg of dough.
You know the total dough weight is 171% of the weight of the flour.
To find the amount of flour, 100% (flour) is to 171% (total %) as n (unknown) is to 25 (Table 21). That is,
1. 100 ÷ 171 = n ÷ 25
2. 25 × 100 ÷ 171 = n
3. 14.62 = n
Table 21: Formula adjusted based on total dough weight
Ingredient % Total Unit
Flour 100.0% 14.62 kg
Water 62.0% 9.064 kg
Salt 2.0% 0.292 kg
Sugar 3.0% 0.439 kg
Shortening 1.5% 0.219 kg
Yeast 2.5% 0.366 kg
Total weight: 171.0% 25.00 kg
As you can see, both the conversion factor method and the baker’s percentage method give you ways to convert recipes. If you come across a recipe written in baker’s percentage, use baker’s percentage to convert the recipe. If you come across a recipe that is written in standard format, use the conversion factor method. | textbooks/workforce/Food_Production_Service_and_Culinary_Arts/Basic_Kitchen_and_Food_Service_Management_(BC_Campus)/01%3A_Trade_Math/1.05%3A_Converting_and_Adjusting_Recipes_and_Formulas.txt |
Learning Objectives
• Describe basic inventory procedures
• Take a basic inventory
• Extend a basic inventory
• Apply ordering and purchasing procedures
02: Inventory Control
A key component in effective kitchen management is inventory control. By knowing what supplies are on hand at a given time, the manager will be able to plan food orders, calculate food costs since the previous inventory, and make menu item changes if needed. By keeping an eye on inventory, it is possible to note potential problems with pilferage and waste.
Managing inventory is like checking a bank account. Just as you are interested in how much money you have in the bank and whether that money is paying you enough in interest, so the manager should be interested in the value of the supplies in the storeroom and in the kitchen.
An inventory is everything that is found within your establishment. Produce, dry stores, pots and pans, uniforms, liquor, linens, or anything that costs money to the business should be counted as part of inventory. Kitchen items should be counted separately from the front of house and bar inventory and so forth.
Regardless of the size of your operation, the principles of inventory control are the same. In larger operations there will be more people and sometimes even whole teams involved with the various steps, and in a small operation all responsibility for managing the inventory may fall on one or two key people.
Effective inventory control can be broken down into a few important steps:
1. Set up systems to track and record inventory
2. Develop specifications and procedures for ordering and purchasing
3. Develop standards and procedures to efficiently receive deliveries
4. Determine the frequency and processes for reconciling inventory
5. Analyze inventory data and determine any areas for improvement
Setting Up Systems to Track and Record Inventory
One of the reasons you take inventory is to determine food costs and to work out cost percentages. There are several procedures that simplify finding the value of goods in storage. These techniques are based on keeping good records of how much supplies cost and when supplies were purchased.
The temptation in small operations is to treat inventory control casually. Perhaps there are only one or two people doing the purchasing and they are usually aware of the supplies that are on hand. This doesn’t eliminate the need to track purchases against sales to see if you are managing your costs as well as you can.
Almost all inventory control procedures are time consuming. Moreover, such records must be kept up-to-date and done accurately. Trying to save a few hours by cutting back on the time needed to keep inventory records may be money poorly saved.
The simplest method for tracking inventory is using a spreadsheet. A simple spreadsheet might list all of the products that are regularly purchased, with the current prices and the numbers on hand at the last inventory count. The prices can be updated regularly as invoices are processed for payment, and a schedule can be set to count the product on hand.
In large operations, the systems need to be more sophisticated as there are more people involved. Purchases might be made by a separate department, inventory records might be kept by a storeroom clerk, and the tracking and counting of inventory might be tied to a system using scanners and barcodes, which in turn may be linked with your sales system so that there is always a record of what should be in stock.
No matter the depth of detail used, having a system to track inventory gives managers a good idea of supplies on hand and a tool to use to manage costs.
Incoming Inventory
The primary reason for establishing a consistent method for accepting ordered goods is to ensure that the establishment receives exactly what has been ordered. Errors frequently occur, and unless the quantity and quality of the items delivered are carefully checked against what was ordered, substantial losses can take place. When receiving procedures are carefully performed, mistakes that could cost the restaurant time and money are avoided. In addition, an effective receiving method encourages honesty on the part of suppliers and delivery people.
Invoices
The most important document in determining if the goods received are the goods ordered is the invoice. An invoice is an itemized list of the goods or products delivered to a food preparation premise. An invoice shows the quantity, quality, price per kilogram or unit, and, in some cases, the complete extension of the cost chargeable. Only by carefully comparing and checking can you be sure that the information on the invoice tallies with the products received. This comparison may require that items be weighed and/or counted.
Whenever possible, the receiver should check the invoice against the purchase order or purchase request slips. This will ensure that the quantity and price of the goods shipped match those listed on the order form. If the invoice is not checked against the purchase order when the goods arrive, there is the potential that you will be missing products you need or receive products that were not ordered or are in incorrect quantities.
In addition, the quality of the goods should be determined before they are accepted. For example, boxes of fresh produce and frozen foods should be opened and inspected to ensure quality.
When you are satisfied that the delivery is in order, sign the invoice. In most cases, the invoice is in duplicate or triplicate: you keep the original and the delivery driver retains the other copy or copies. Once you have signed, you have relieved the delivery company of its responsibilities and the supplies now belong to your company. You may, therefore, become responsible for any discrepancies between what is on the invoice and what has been delivered. It is good practice to bring any discrepancies or errors to the attention of the driver and have him or her acknowledge the mistake by signing the invoice. If a credit note is issued, that should also be marked on the invoice by the driver.
Note: Do not sign the invoice until you are sure that all discrepancies have been taken care of and recorded on the invoice.
Take the signed invoice and give it to whoever is responsible for collecting invoices for the company.
The receiving of deliveries can be time consuming for both the food establishment and the delivery service. Often the delivery people (particularly if they are not the supplier) will not want to wait while these checks are done. In this case, it is important that your company has an understanding with the supplier that faults discovered after the delivery service has left are the supplier’s problems, not yours.
Once the invoices have been signed, put the delivered products in the proper locations. If you are required to track incoming inventory, do so at the same time.
Outgoing Inventory
When a supply leaves the storeroom or cooler, a record must be kept to track where it has gone. In most small operations, the supplies go directly to the kitchen where they are used to produce the menu items. In an ideal world, accurate records of incoming and outgoing supplies are kept, so knowing what is on hand is a simple matter of subtraction. Unfortunately, systems aren’t always that simple.
In a smaller operation, knowing what has arrived and what gets used every day can easily be reconciled by doing a regular count of inventory. In larger operations and hotels, the storage rooms and coolers may be on a different floor than the kitchen, and therefore a system is needed that requires each department and the kitchens to requisition food from the storeroom or purchasing department, much like a small restaurant would do directly from the supplier. In this model, the hotel would purchase all of the food and keep it in a central storage area, and individual departments would then “order” their food from the storerooms.
Requisitions
To control inventory and to determine daily menu costs in a larger operation, it is necessary to set up a requisition procedure where anything transferred from storage to the kitchen is done by a request in writing. The requisition form should include the name and quantity of the items needed by the kitchen. These forms often have space for the storeroom clerk or whoever handles the storeroom inventory to enter the unit price and total cost of each requested item (Figure 1).
In an efficiently run operation, separate requisition forms should be used by serving personnel to replace table supplies such as sugar, salt, and pepper. However, often personnel resist using requisition forms because they find it much easier and quicker to simply enter the storage room and grab what is needed, but this practice leaves no record and makes accurate record keeping impossible. To reduce the possibility of this occurring, the storage area should be secure with only a few people having the right to enter the rooms, storage freezers, or storage refrigerators.
Figure 1: Sample Requisition Form
Date: _____________
Department: Food Service
Quantity Description Unit Cost Total Cost
6 #10 cans Kernel corn
25 kg Sugar
20 kg Ground beef
6 each Pork loins
Charge to:
Catering Dept.
C. Andrews
Chef
Not only does the requisition keep tabs on inventory, it also can be used to determine the dollar value of foods requested by each department and so be used to determine expenses. In a larger operation where purchases may be made from different suppliers at different prices, it may be necessary to tag all staples with their costs and date of arrival. Expensive items such as meats are often tagged with a form that contains information about weight, cost per unit (piece, pound or kilogram), date of purchase, and name of supplier.
Pricing all items is time consuming, but that time will soon be recovered when requisition forms are being filled out or when the stock has to be given a monetary value. In addition, having prices on goods may help to remind staff that waste is costly.
Inventory Record Keeping
There are two basic record keeping methods to track inventory. The first is taking perpetual inventory. A perpetual inventory is simply a running balance of what is on hand. Perpetual inventory is best done by keeping records for each product that is in storage, as shown in Figure 2.
When more of the product is received, the number of cans or items is recorded and added to the inventory on hand; when some of the product is requisitioned, the number going out is recorded and the balance is reduced. In addition, the perpetual inventory form can indicate when the product should be reordered (the reorder point) and how much of the product should ideally be on hand at a given time (par stock).
In small operations, a perpetual inventory is usually only kept for expensive items as the time (and cost) of keeping up the records can be substantial.
The second inventory record keeping system is taking a physical inventory. A physical inventory requires that all items in storage be counted periodically. To be an effective control, physical inventory should be taken at least monthly. The inventory records are kept in a spreadsheet or in another system reserved for that purpose.
The inventory sheet (Figure 3) can list the items alphabetically or in the order they will appear on the shelves in the storage areas.
Figure 3: Physical Inventory Form
Physical Inventory Form: March
Product Unit Count Unit Price Total Value
Lima beans 6 #10 4 1/3 \$23.00 \$99.60
Green beans 6 #10 3 5/6 28.95 110.98
Flour 25 kg bag 3 14.85 44.55
Rice 50 kg bag 1 32.50 32.50
Total \$593.68
In addition to the quantity of items, the inventory usually has room for the unit cost and total value of each item in storage. The total values of the items are added together to give the total dollar value of the inventory. This is also knows as extending the inventory. The total value of the inventory is known as the closing inventory for the day the inventory was taken. This amount will also be used as the opening inventory to compare with the next physical inventory. If the inventory is taken on the same day of each month, the figures can be used to accurately determine the monthly food cost.
The physical inventory is used to verify the accuracy of the perpetual inventory. For example, if 15 whole beef tenderloins are counted during a physical inventory, but the perpetual inventory suggests that there should be 20 tenderloins on hand, then a control problem exists and you need to find the reason for the variance.
Computerized Inventory Control
Most people today use computerized systems to calculate, track, and extend inventory. These systems enable the restaurant to have a much tighter and more accurate control over the inventory on hand and the costs of that inventory. Having access to information such as ordering history and the best price paid is just one of the benefits of these systems. They can also help the purchaser predict demand levels throughout the year. These programs in many cases are also integrated with the point-of-sale (POS)system used to track sales, and can even remove an item from a computerized inventory list when the waiter registers the sale of any menu item on the restaurant terminal. That is, if a customer orders one chicken dish from the menu, all the items required to make one portion of the chicken are discounted from inventory. This provides management with an constant up-to-date perpetual inventory of most inventory items.
Smaller operations will use a spreadsheet application to manage inventory, so you should also be familiar with a program like Microsoft Excel if you are responsible for ordering and inventory. The information required for the program to do the calculations properly is available from the invoices received with your supplies. That is, the quantities and prices of the goods you most recently received should be entered into the computer program either by you or by the restaurant’s purchaser. These prices and quantities are automatically used to calculate the cost of the goods on hand. This automated process can save you an enormous amount of time and, if the information entered into the computer is accurate, may also save you money. In any inventory system, there is always a possibility for error, but with computerized assistance, this risk is minimized.
Pricing and Costing for Physical Inventory
The cost of items purchased can vary widely between orders. For example, cans of pineapple might cost \$2.25 one week, \$2.15 the second week, and \$2.60 another week. The daily inventory reports will reflect the changes in price, but unless the individual cans have been marked, it is difficult to decide what to use as a cost on the physical inventory form.
There are several different ways to view the cost of the stock on the shelves if the actual cost of each item is difficult to determine. Most commonly, the last price paid for the product is used to determine the value of the stock on hand. For example, if canned pineapple last cost \$2.60 a can and there are 25 cans on hand, the total value of the pineapple is assumed to be \$65 (25 x \$2.60) even though not all of the cans may have been bought at \$2.60 per can.
Another method for costing assumes the stock has rotated properly and is known as the FIFO (first-in first-out) system. Then, if records have been kept up-to-date, it is possible to more accurately determine the value of the stock on hand.
Here is an example showing how the FIFO system works.
Example 10
The daily inventory shows the following:
Date Number and value of cans
Opening inventory, 1st of month 15 cans @ \$2.15 = \$32.25
Received on 8th of month 24 cans @ \$2.25 = \$54.00
Received in 15th of month 24 cans @ \$2.15 – \$51.60
Received on 23 of month 12 cans @ \$2.60 – \$31.20
If the stock has rotated according to FIFO, you should have used all of the opening inventory, all of the product received on the 8th, and some of the product received on the 15th. The 25 remaining cans must consist of the 12 cans received on the 23rd and 13 of the cans received on the 15th. The value of these cans is then
12 cans @ \$2.60 = \$31.20
13 cans @ \$2.15 = \$27.95
Total = \$59.15
As you can see, the choice of costing method can have a marked effect on the value of stock on hand. It is always advisable to use the method that best reflects the actual cost of the products. Once a method is adopted, the same method must be used consistently or the statistical data generated will be invalid.
Costing Prepared or Processed Items
When you are building your inventory forms, be sure to calculate the costs of any processed items. For instance, sauces and stocks that you make from raw ingredients need to be costed accurately and recorded on the spreadsheet along with purchased products so that when you are counting your inventory you are able to reflect the value of all supplies on the premises that have not been sold.
(We will discuss more about calculating the costs of products and menu items later in this book.)
Inventory Turnover
When accurate inventory records are kept, it is possible to use the data in the records to determine the inventory turnover rate. The inventory turnover rate shows the number of times in a given period (usually a month) that the inventory is turned into revenue. An inventory turnover of 1.5 means that the inventory turns over about 1.5 times a month, or 18 times a year. In this case, you would have about three weeks of supplies in inventory at any given time (actually 2.88 weeks, which is 52 weeks ÷ 18). Generally, an inventory turnover every one to two weeks (or two to three times per month) is considered normal.
A common method used to determine inventory turnover is to find the average food inventory for a month and divide it into the total food cost for the same month. The total food cost is calculated by adding the daily food purchases (found on the daily receiving reports) to the value of the food inventory at the beginning of the month and subtracting the value of the food inventory at the end of the month.
That is,
average food inventory = (beginning inventory + ending inventory) ÷ 2
cost of food = beginning inventory + purchases − ending inventory
inventory turnover = (cost of food) ÷ (average food inventory)
Example 11
A restaurant has a beginning inventory of \$8000 and an ending inventory of \$8500. The daily receiving reports show that purchases for the month totalled \$12,000. Determine the cost of food and the inventory turnover.
Cost of food = \$8000 + \$12 000 − \$8500 = \$11 500
Average food inventory = (\$8000 + \$8500) ÷ 2 = \$8250
Inventory turnover = \$11 500 ÷ \$8250 = 1.4
The turnover rate in the example would be considered low and would suggest that the business has invested too much money in inventory. Having a lot of inventory on hand can lead to spoilage, high capital costs, increased storage space requirements, and other costs.
Inventory turnover rates are not exact, for a few reasons. One is that in many food operations, accurate inventory records are usually kept only for more expensive items. Another is that the simple food cost used in the calculation does not truly reflect the actual food cost. (Food costs are discussed in another chapter in this book.) In addition, not all inventory turns over at the same rate. For example, perishables turn over as quickly as they arrive while canned goods turn over more slowly.
Even though turnover rates are not exact, they do give managers at least a rough idea of how much inventory they are keeping on hand.
Image Descriptions
Figure 2 Image description: A sample perpetual inventory form for canned peaches.
Item: Canned Peaches (540 mL). Reorder Point: 10, Par stock: 15
Date In Out Balance
June 16 None 3 12
June 17 None 3 9
June 18 6 None 15
June 19 None 2 13
[Return to Figure 2] | textbooks/workforce/Food_Production_Service_and_Culinary_Arts/Basic_Kitchen_and_Food_Service_Management_(BC_Campus)/02%3A_Inventory_Control/2.01%3A_Basic_Inventory_Procedures.txt |
The purchasing process is an essential part of every food service operation. All competent cooks should be skilled in buying the appropriate ingredients, in accurate amounts, at the right time, and at the best price.
Every kitchen operation has different purchasing procedures. But there is one rule that should always be followed:
Buy only as much as it is anticipated will be needed until the next delivery.
This will ensure that foods stay fresh and will create a high inventory turnover. All foods deteriorate in time, some more quickly than others. It is the job of the purchaser to ensure that only those quantities that will be used immediately or in the near future are purchased.
Market Sourcing
Sources of supply vary considerably from location to location. Large cities have a greater number and variety of suppliers than do small towns and isolated communities. Purchasers should establish contact with available suppliers such as wholesalers, local producers and packers, retailers, cooperative associations, and food importers. In most instances, the person in charge of buying will contact several suppliers to obtain the necessary foods. Some wholesalers diversify their product lines in order to meet all food-related kitchen needs.
Food products are obtained from various sources of supply. For example, a packing house supplies meat and meat products, while a food wholesaler supplies dry goods. Once business is established with a supplier, all transactions should be well documented and kept readily available on file.
There are two major food categories: perishables and non-perishables.
Perishables
Perishable items include fruits, vegetables, fresh fish and shellfish, fresh meats, poultry, and dairy products. As a rule, perishables are bought frequently to ensure freshness. Frozen foods, such as vegetables, fish and meat products, have a longer lifespan and can be ordered less frequently and stored in a freezer.
Non-perishables
Non-perishable items include dry goods, flour, cereals, and miscellaneous items such as olives, pickles, and other condiments. These can be ordered on a weekly or monthly basis.
Keep in mind that just because something does not go bad isn’t a reason to buy it in quantities larger than you need. Every item in your inventory is equal to a dollar amount that you could be saving or spending on something else. Consider that a case of 1000 sheets of parchment paper may cost \$250. If you have a case and a half sitting in your inventory, but only use a few sheets a day, that is a lot of money sitting in your storeroom.
Factors That Impact Prices
Food products in particular fluctuate in price over the year, due to many factors:
• Seasonality: When food is in season, there is more of it available in the local food supply, bringing prices down. Additionally, foods in season are usually of higher quality and have longer shelf life than those that are out of season and need to be transported long distances to market.
• Weather: Severe weather can have a huge impact on the cost of food. Drought, flooding, and unseasonable frost have all affected major produce-supplying areas of the world in recent years, causing a rise in prices for many items.
• Costs of transportation: If the cost of fuel or transportation rises, so does the cost of food that needs to travel to market.
• Commodity prices: A number of foods are traded on the commodity market, such as meats and grains. These prices fluctuate as buyers who trade in these products in large volumes buy and sell, much like the stock market.
Before purchasing any food items, ask the following questions.
• When is the item to be used?
• Which supplier has the best price and the best quality? Where an item is purchased should be determined by the price and the quality of the available supplies. When ordering supplies, it is advisable to get prices from at least three sources, then purchase from the supplier who quotes the best price for comparable quality.
• When will the item be delivered? Depending on the distance of the food service establishment from the supplier, delivery may take hours or days. Remember, it is extremely difficult to maintain food quality and consistency if you do not know when your order will be delivered. For this reason, menu planning and a running inventory are two of the most important aspects of purchasing procedures.
Specifications
Meat, seafood, poultry, processed fruits and vegetables, and fresh fruits and vegetables can be ordered under different specifications. For example,
• Meats can be ordered by grade, cut, weight/thickness, fat limitation, age, whether fresh or frozen, and type of packaging.
• Seafood can be ordered by type (e.g., fin fish/shellfish), species, market form, condition, grade, place of origin, whether fresh or frozen, count, size, and packaging,
• Poultry can be ordered by type, grade, class (e.g., broiler, fryer), style (e.g., breasts, wings), size, whether fresh or frozen, and packaging.
• Processed fruits and vegetables can be ordered by grade (sometimes), variety, packaging size and type, drained weight, count per case, packing medium, and whether canned or frozen.
• Fresh fruits and vegetables can be ordered by grade (sometimes), variety, size, weight per container, growing area, and count per container,
Figure 4 shows an example of a purchasing specification sheet that might be kept in a commercial kitchen or receiving area.
Figure 4: Purchasing Specifications
Beef
Beef Grade Weight, Size, and Cut Specifications
Prime rib Grade AA 7 kg, fully trimmed
New York strip Grade AAA 6 kg, bone out, fully trimmed, max. 15 cm width, min. 5 cm depth
Tenderloin Grade AAA 3 kg, fully trimmed to silverside
Roast sirloin Grade A 7 kg, boneless butt
Short loins Grade AAA 6 kg, fully trimmed, 5 cm from eye
Pork
Pork Grade Weight, Size, and Cut Specifications
Pork leg Fresh—Canada #1 6 kg, oven ready, lean
Pork loin Fresh—Canada #1 5-6 kg, trimmed, lean
Ham 6-8 kg, fully cooked, lean, bone in
Poultry
Poultry Grade Weight, Size, and Cut Specifications
Chicken—Frying Fancy, Eviscerated 1.5 kg, always fresh
Turkey Fancy, Eviscerated 9-13 kg
Lamb
Lamb Grade Weight, Size, and Cut Specifications
Legs Fresh—Canada #1 3-5 kg, bone in
Lamb loin 2-3 kg, trimmed with all fat removed
Seafood
Seafood Grade Weight, Size, and Cut Specifications
Shrimp Jumbo 24-30/kg, fresh
Oysters Canada #1 35/L
Contract Buying
Some restaurants and hotels, particularly those belonging to chains, will have contracts in place for the purchasing of all products or for certain items. This may mean that the property can only purchase from a specific supplier, but in return it will have negotiated set pricing for the duration of the contract. This has advantages and disadvantages. On the positive side, the contract price remains stable and the job of managing food costs becomes more consistent since there are no price fluctuations. On the negative side, contract buying takes away the opportunity to compare prices between suppliers and take advantage of specials that may be offered.
Purchasing Procedures
In most kitchens, purchasing and ordering are done by the chef and sous-chefs, although in larger hotels there may be purchasing departments assigned this responsibility. Most kitchens will have a list of suppliers, contacts, delivery dates and schedules, and order sheets with par stock levels to make purchasing easier. For a special function or event, such as a banquet, it may also be necessary to determine the required supplies for that function alone.
Portion Control Chart
To calculate the quantities of food items to be ordered for any size banquet, a portion control chart must be consulted first. Most establishments will have a portion control chart similar to the one shown in Figure 5. The chart indicates the portions to be used per person for any given menu item.
Figure 5: Portion control chart
Portion control chart
Food Item Menu Item Portion Size
Shrimp Shrimp cocktail 80 g (2.82 oz.)
Lemon Shrimp cocktail 1 wedge (6/lemon)
Cocktail sauce Shrimp cocktail 60 mL (2.11 oz.)
Head lettuce Tossed salad 1/4 head
Tomato Tossed salad 1/2 each
Dressing Tossed salad 60 mL (2.11 oz.)
Prime rib, raw, trimmed ready Prime rib 500 g (17.6 oz.)
Potato Baked potato 1 each (100 count)
Green beans Green beans 80 g (2.82 oz.)
Carrots Carrots 80 g (2.82 oz.)
Strawberries Fresh strawberries 100 g (3.52 oz.)
Whipping cream Berries and cream 60 mL (2.11 oz.)
Coffee Coffee 500 g (17.6 oz.) for 75 people
Coffee cream Coffee 60 mL (2.11 oz.)
One use for a portion control chart is to estimate the quantity of major ingredients and supplies needed to produce a predicted number of menu servings.
You need to prepare shrimp cocktails and prime rib for a 100-person banquet. Using the portion control chart in Figure 5, you can quickly determine what amounts of major ingredients (Figure 6).
Figure 6L Calculating purchase amounts
Figure 6: Calculating purchase amounts
Required Servings Amount to Order
100 x 80 g shrimp 8000 g or 8 kg (17.6 lbs.) shrimp
100 x 1 wedge of lemon 100 wedges = 17 lemons (6 wedges per lemon)
100 x 1/4 head of lettuce 25 heads lettuce
100 x 500 g prime rib raw oven ready 50 kg (110 lbs.) prime rib
Purchase Order Chart with Par Levels
The primary purpose for using a purchasing standard is to ensure that sufficient quantities of all food are on hand to meet daily requirements. To establish and maintain these standards, food inventory must become a daily routine. Having set par levels (the amount you should have on hand to get through to the next order) will help in this regard.
There are three main things you need to know:
• Amount required (par level)
• Amount on hand
• Amount to order
To find the amount to order, subtract the amount on hand from the amount required (Figure 7). In some cases, you may have to order a minimum amount based on the package size, so will need to round your quantity up (such as the whole tub of garlic and full cases of mushrooms, apples, and lettuce in Figure 7).
Figure 7: Purchase order chart
Meats
Meats Amount Required (Par Level) Amount on Hand Amount to Order Actual Order
• Corned beef
10 kg 2 kg 8 kg 8 kg
• Ribs of beef
20 kg 5 kg 15 kg 15 kg
• Ground beef
10 kg 10 kg 10 kg
• Veal liver
5 kg 500 g 4.5 kg 4.5 kg
• Pork loin
10 kg 3 kg 7 kg 7 kg
Fish
Fish Amount Required (Par Level) Amount on Hand Amount to Order Actual Order
• Sole fillet
25 kg 5 kg 20 kg 20 kg
Vegetables
Vegetables Amount Required (Par Level) Amount on Hand Amount to Order Actual Order
• Garlic, peeled
2 kg tub 250 g 1.750 kg 2 kg tub
• Mushrooms
5 kg case 500 g 4.5 kg 5 kg case
• Lettuce
2 cases (24/case) 12 (1/2 case) 1 1/2 cases 2 cases
Fruits
Fruits Amount Required (Par Level) Amount on Hand Amount to Order Actual Order
• Apples
2 cases 1/2 case 1 1/2 cases 2 cases
• Strawberries
10 kg 10 kg
• Oranges
1 case 2 cases
Integrating these par levels into your regular ordering sheets or your ordering system will make it very easy to manage inventory coming in.
More and more suppliers are moving to online ordering systems, which have current prices, case sizes, and often your purchase history available to you when placing an order. Online ordering can often be more convenient as the person placing the order does not have to make calls into an order desk during regular office hours. | textbooks/workforce/Food_Production_Service_and_Culinary_Arts/Basic_Kitchen_and_Food_Service_Management_(BC_Campus)/02%3A_Inventory_Control/2.02%3A_Purchasing.txt |
Learning Objectives
• Describe food cost controls
• Perform yield and cost calculations
• Cost and price menu items
• Describe overall food costs
• Describe the principles of menu engineering
03: Food Costing
Food service establishments are businesses. In order to stay in business, everyone involved with the enterprise should have at least a basic idea of how costs are determined and how such costs have an impact on an operating budget.
Food costs are controlled by five standards to which all employees and managers must adhere:
• Standard purchase specifications
• Standard recipes
• Standard yields
• Standard portion sizes
• Standard portion costs
To calculate the cost of each item, you need to understand the relationship between standardized recipes, standard portions, and yield tests. All of these play a role in calculating the cost of each item on your menu.
After goods are ordered, there should be no surprises when the goods arrive. The more specific the order, the less the chance of receiving supplies that are too high in price, too poor in quality, or too many in number.
Specifications can include brand names, grades of meat, product size, type of packaging, container size, fat content, count per kilogram, special trimming, and so on. The specifications should be specific, realistic, and easy to verify.
Precise specifications can:
• Reduce purchasing costs as higher quality products need not be accepted
• Ensure constant quality in menu items
• Allow for accurate competitive bidding among suppliers and so reduce costs
Specifications usually do not include general delivery procedures or purchase price. Directions and prices can change quickly. Specifications should be well thought out and are usually not subject to quick change.
Standardized Recipes
A standardized recipe is one that holds no surprises. A standardized recipe will produce a product that is close to identical in taste and yield every time it is made, no matter who follows the directions. A standardized recipe usually includes:
• A list of all ingredients including spices and herbs
• Exact quantities of each ingredient (with the exception of spices that may be added to taste)
• Specific directions for the order of operations and types of operations (e.g., blend, fold, mix, sauté)
• The size and number of portions the recipe will produce
Standard Yields
The yield of a recipe is the number of portions it will produce. Standard yields for high-cost ingredients such as meat are determined by calculating the cost per cooked portion. For example, a 5 kg roast might be purchased for \$17 a kilogram. The cooked roast is to be served in 250 g portions as part of a roast beef dinner. After trimming and cooking, the roast will not weigh 5 kg, but significantly less. By running a yield test, the cost per portion and unit weight, and the standard yield and yield percentage, can be determined.
Standard Portions
A standard recipe includes the size of the portions that will make up a serving of the recipe. Controlling portion size has two advantages in food management: portion costs for the item will be consistent until ingredient or labour costs increase, and customers will receive consistent quantities each time they order a given plate or drink.
Standard portions mean that every plate of a given dish that leaves the kitchen will be almost identical in weight, count, or volume. Only by controlling portions is it possible to control food costs. If one order of bacon and eggs goes out with six rashers of bacon and another goes out with three rashers, it is impossible to determine the actual cost of the menu item.
Adhering to the principles of standard portions is crucial to keeping food costs in line. Without portion control, there is no consistency. This not only could have drastic effects on your food costs (having no real constant costs to budget for) but also on your customers. Customers appreciate consistency. They expect that the food you prepare will taste good, be presented properly, and be the same portion size every time they order it. Consider how the customer would feel if the portion size fluctuated with the cook’s mood. A cook’s bad mood might mean a smaller portion or, if the cook was in a good mood because the work week was over, the portion might be very large. It may be hard to grasp the importance of consistency with one single portion, but consider if fast-food outlets did not have portion control. Their costs as well as their ordering and inventory systems would be incredibly inaccurate, all of which would impact negatively on their profit margin.
Strict portion control has several side benefits beyond keeping costs under control. First, customers are more satisfied when they can see that the portion they have is very similar to the portions of the same dish they can see around them. Second, servers are quite happy because they know that if they pick up a dish from the kitchen, it will contain the same portions as another server’s plate of the same order.
Simple methods to control portion include weighing meat before it is served, using the same size juice glasses when juice is served, counting items such as shrimp, and portioning with scoops and ladles that hold a known volume. Another method is using convenience products. These products are received usually frozen and are ready to cook. Portions are consistent in size and presentation and are easily costed out on a per unit basis. This can be helpful when determining the standard portion costs.
Note: Using convenience products is usually more costly than preparing the item in-house. However, some chefs and managers feel that using premade convenience products is easier than hiring and training qualified staff. But always keep in mind that if the quality of the convenience item is not comparable to an in-house made product, the reputation of the restaurant may suffer.
Standard portions are assured if the food operation provides and requires staff to use such tools as scales, measured ladles, and standard size scoops. Many operations use a management portion control record for menu items, similar to the one shown in Figure 8. The control record is posted in the kitchen so cooks and those who plate the dishes know what constitutes standard portions. Some operations also have photographs of each item posted in the kitchen area to remind workers what the final product should look like.
Figure 8: Portion control record
Portion Control Record
Item Purchased Size Yield % Cooked Yield Portion Size No. of Portions
Baked ham 6-7 kg 50% 3.0-3.5 kg
Lunch 50 g 60-70
Dinner 85 g 35-41
Prime rib 9-12 kg 40% 3.6-4.8 kg 150 g 24-32
Fillet of sole 500 g 100% 500.0 g
Lunch 50 g 10
Dinner 85 g 6
Potatoes: 50 kg
• Roasted Potatoes
75% Peeled – 37.5 kg 100 g 375
• French fries
56% Peeled – 28.0 kg 100 g 280
Daily veg 5 kg
Green beans 80% Trimmed – 4 kg 50 g 80
Carrots 80% Peeled – 4 kg 50 g 80
Standard Portion Costs
A standard recipe served in standard portions has a standard portion cost. A standard portion cost is simply the cost of the ingredients (and sometimes labour) found in a standard recipe divided by the number of portions produced by the recipe. Standard portion costs change when food costs change, which means that standard portion costs should be computed and verified regularly, particularly in times of high inflation. If market conditions are fairly constant, computing standard portion costs need not be done more than every few months.
Details about recipe costs are not usually found on a standard recipe document but on a special recipe detail and cost sheet or database that lists the cost per unit (kilogram, pound, millilitre, ounce, etc.) and the cost per amount of each ingredient used in the recipe or formula.
The standard portion cost can be quickly computed if portions and recipes are standardized. Simply determine the cost of each ingredient used in the recipe and ingredients used for accompaniment or garnish.
The ingredients in a standard recipe are often put on a recipe detail sheet (Figure 9). The recipe detail sheet differs from the standard recipe in that room is provided for putting the cost of each ingredient next to the ingredient. Recipe detail sheets often have the cost per portion included as part of their information, and need to be updated if ingredient costs change substantially. They can also be built in a POS system database or spreadsheet program that is linked to your inventory to allow for the updating of recipe costs as ingredient costs change.
Figure 9: Menu item – Seafood Newburg
Yield: 10 portions
Portion size: 125 g of seafood
Selling price: \$12.99
Cost/portion: \$4.07
Food cost %: 31.3%
Recipe detail and cost sheet
Ingredients Quantity Units Cost/Unit Extension
Lobster meat 500 g kg \$38.00 \$19.00
Scallops 250 g kg \$25.00 \$6.25
Shrimps 250 g kg \$14.00 \$3.50
Sole 250 g kg \$8.50 \$2.13
Cream, heavy 250 mL L \$4.00 \$1.00
Fish Velouté 750 mL L \$1.00
Butter 250 g 500 g \$2.85 \$1.43
Pepper and salt
Paprika 5 g \$0.15
Sherry 250 mL 750 mL \$12.00 \$4.00
Egg yolks 6 12 \$2.00 \$1.00
Patty shells 10 each \$0.12 \$1.20
Total \$40.66
Procedure: Quarter the scallops, dice the lobster meat, halve the shrimps, and chop the sole before sautéing well in melted butter. Add sherry and simmer for a few minutes. Add the fish velouté sauce and paprika and continue to simmer. Combine the egg yolks and the heavy cream before adding them slowly to the simmering pan. Season to taste with salt and white pepper. Serve in patty shells.
Note that the portion cost and selling price used in Figure 9 is for the Seafood Newburg alone (a true à la carte price) and not the cost of all accompaniments found on the plate when the dish is served.
For example, the cost of bread and butter, vegetables, and even garnishes such as a wedge of lemon and a sprig of parsley must be added to the total cost to determine the appropriate selling price for the Seafood Newburg.
Costing Individual Items on a Plate
If you need to determine the total cost of a plate that has multiple components, rather than a recipe, you can follow the procedure in the example below.
Example 11
Standard order of bacon and eggs: the plate contains two eggs, three strips of bacon, toast, and hash browns.
The cost of ingredients used for accompaniment and garnish can be determined by using the standard portion cost formula, which is the purchase price of a container (often called a unit) divided by the number of portions in the container. That is,
standard portion cost = unit cost ÷ portions in the unit
An example is a carton of eggs. If eggs cost \$2.00 a dozen and a standard portion in a menu breakfast item is two eggs, the standard portion cost can be found.
Recall the equation:
standard portion cost = unit cost ÷ portions in the unit
Now, find the portions in the unit.
portions in the unit = number in unit ÷ number in a portion
= 12 ÷ 2
= 6
That is, there are six 2-egg portions in a dozen eggs.
Substitute the known quantities into the equation.
standard portion cost = unit cost ÷ portions in unit
= \$2.00 ÷ 6
= \$0.33
You could get the same answer by calculating how much each egg in the dozen is worth (\$2.00 ÷ 12 = \$0.17) and then multiplying the cost per egg by the number of eggs needed (\$0.17 × 2 = \$0.34). No matter what method is used, the standard portion of two eggs in this order of bacon and eggs has a standard portion cost of \$0.34.
You can find the standard portion cost of the bacon in the same way. If a 500 g package of bacon contains 20 rashers and costs \$3.75, the standard portion cost of a portion consisting of four rashers can be found quickly:
portions in the unit = 20 ÷ 4
= 5
standard portion cost = unit cost/portions in unit
= \$3.75 ÷ 5
= \$0.75
The bacon and eggs on the plate would have a standard portion cost of \$1.09. You could determine the cost of hash browns, toast, jam, and whatever else is on the plate in the same manner.
Often, restaurants will serve the same accompaniments with several dishes. In order to make the costing of the entire plate easier, they may assign a “plate cost,” which would include the average cost of the standard starch and vegetable accompaniments. This makes the process of pricing daily specials or menu items that change frequently easier, as you only need to calculate the cost of the main dish and any specific sauces and garnishes, and then add the basic plate cost to the total to determine the total cost of the plate.
Figures 10 and 11 provide an example for calculating the basic plate cost and the cost of daily features.
Figure 10
Calculating basic plate cost for daily meat special
Mashed potatoes, one serving \$0.50
Mixed vegetables, one serving \$0.75
Demi-glace, one serving \$0.30
Herb garnish \$0.20
Total basic plate cost \$1.75
Figure 11
Calculating the cost of daily features using a basic plate cost
Day Feature Feature Cost per Portion Basic Plate Cost Total Cost
Monday Roast beef \$5.00 + \$1.75 = \$6.75
Tuesday Pork chop \$3.75 + \$1.75 = \$5.50
Wednesday Half roast chicken \$4.00 + \$1.75 = \$5.75 | textbooks/workforce/Food_Production_Service_and_Culinary_Arts/Basic_Kitchen_and_Food_Service_Management_(BC_Campus)/03%3A_Food_Costing/3.01%3A_Controlling_Food_Costs.txt |
Yield in culinary terms refers to how much you will have of a finished or processed product. Professional recipes should always state a yield; for example, a tomato soup recipe may yield 15 L, and a muffin recipe may yield 24 muffins. Yield can also refer to the amount of usable product after it has been processed (peeled, cooked, butchered, etc.)
For example, you may be preparing a recipe for carrot soup. The recipe requires 1 kg of carrots, which you purchase. However, once you have peeled them and removed the tops and tips, you may only have 800 grams of carrots left to use.
In order to do accurate costing, yield testing must be carried out on all ingredients and recipes. When looking at yields, you must always consider the losses and waste involved in preparation and cooking. There is always a dollar value that is attached to vegetable peel, meat and fish trim, and packaging like brines and syrups. Any waste or loss has been paid for and is still money that has been spent. This cost must always be included in the menu price.
Note: Sometimes, this “waste” can be used as a by-product. Bones from meat and fish can be turned into stocks. Trimmings from vegetables can be added to those stocks or, if there is enough, made into soup.
All products must be measured and yield tested before costing a menu. Ideally, every item on a menu should be yield tested before being processed. Most big establishments will have this information on file, and there are many books that can also be used as reference for yields, such as The Book of Yields: Accuracy in Food Costing and Purchasing.
Example 12: The procedure for testing yields
1. Record the original weight/volume of your item. This is your raw weight or as purchased (AP) weight.
1. Whole tenderloin – 2.5 kg
2. Whole sockeye salmon – 7.75 kg
3. Canned tuna flakes in brine – 750 mL
2. Process your product accordingly, measure and record the waste or trim weight.
1. Tenderloin fat, sinew, chain, etc. – 750 g tenderloin trim
2. Salmon head, bones, skin, etc. – 2.75 kg salmon trim
3. Brine – 300 mL canned tuna waste
3. Subtract the amount of trim weight from the AP weight and you will have what is referred to as your processed or edible product (EP) weight. The formula is: AP weight – waste = EP weight.
1. 2500 g − 750 g = 1750 g processed tenderloin
2. 7750 g − 2750 g = 5000 g processed salmon
3. 750 mL − 300 mL = 400 mL processed canned tuna
4. Get your yield percentage by converting the edible product weight into a percentage. The formula is EP weight ÷ AP weight × 100 = yield %.
1. (1750 ÷ 2500) × 100 = 70% for the tenderloin
2. (5000 ÷ 7750) × 100 = 64.51% for the salmon
3. (400 ÷ 750) × 100 = 53.33% for the canned tuna
Yield percentage is important because it tells you several things: how much usable product you will have after processing; how much raw product to actually order; and the actual cost of the product per dollar spent.
Using Yield to Calculate Food Costs
Once you have your yield percentage, you can translate this information into monetary units. Considering the losses incurred from trimmings and waste, your actual cost for your processed ingredient has gone up from what you originally paid, which was your raw cost or AP cost. These calculations will provide you with your processed cost or EP cost.
Example 13: The procedure for determining EP cost
1. Record the AP cost, what you paid for the item:
1. Whole tenderloin – \$23.00/kg
2. Whole sockeye salmon – \$5.00/kg
3. Canned tuna flakes in brine – \$5.50/750 mL can
2. Obtain your factor. This factor converts all your calculations into percentages. The formula is:
1. 100 ÷ yield % = factor
2. 100 ÷ 70 tenderloin = 1.42
3. 100 ÷ 64.51 salmon = 1.55
4. 100 ÷ 53.33 canned tuna = 1.875
3. Once the factor has been determined, it is now an easy process to determine your EP cost. The formula is: factor × as purchased cost per (unit) = edible product cost per (unit)
1. Tenderloin \$23.00 × 1.42 = \$32.66/kg
2. Salmon \$5.00 × 1.55 = \$7.75/kg
3. Canned tuna \$5.50 × 1.875 = \$10.78/750 mL
There could be a considerable difference in costs between the raw product and the processed product, which is why it is important to go through all these steps. Once the EP cost is determined, the menu price can be set.
Yield Tests and Percentages
Meat and seafood products tend to be the most expensive part of the menu. They also have significant amounts of waste, which must be accounted for when determining standard portion cost.
When meat is delivered, unless it has been purchased precut, it must be trimmed and cut into portions. The losses due to trimming and cutting must be accounted for in the portion cost of the meat. For example, if a 5 kg roast costing \$8 a kilogram (total cost is \$40) is trimmed of fat and sinew and then weighs 4 kg, the cost of usable meat (the EP cost), basically, has risen from \$8 a kilogram to \$10 a kilogram (\$40 ÷ 4 kg). The actual determination of portion cost is found by conducting a meat cutting yield test.
The test is conducted by the person who breaks down or trims the wholesale cut while keeping track of the weight of the parts. The information is placed in columns on a chart, as shown in Figure 12. The column names and their functions are discussed below.
Figure 12: Meat Cutting Yield Test
Item: Pork Loin – Grade A-1
Date:
Meat cutting yield test
Part of the meat Weight % of total Value per kg Total value Cost factor EP cost (per kg) Portion size Portion cost
Whole piece (AP) 2.5 kg \$12.14 \$30.35
Fat and gristle 850 g 34% \$0.20 \$0.17
Loss in cutting 100 g 4% 0
Trim 250 g 10% \$7.49 \$1.87
Usable meat 1300 g 52% \$28.31 1.79 \$21.78 250 g \$5.45
The parts of the meat are listed on the yield test sheet under the heading “Breakdown.” In the example in Figure 12, a pork loin has been broken down into fat and gristle, loss in cutting, trim, and usable meat. Various measures and calculations are then recorded in the different columns:
• Weight: Next to the breakdown column the weights of the individual parts are listed.
• Percentage of total weight: The third column contains the percentage of the original piece by weight. The column is headed “% of total weight,” which reminds us how to calculate the percentages. That is,
% of total weight = weight of part ÷ total weight
For example, in Figure 12, the fat and gristle weighs 850 g (or 0.850 kg). The total weight of the pork loin before trimming is 2.5 kg.
Example 14: Percentage of fat and gristle equation
% of fat and gristle = weight of part ÷ total weight
= 0.850 kg ÷ 2.5 kg
= 0.34
= 34%
Using the same procedure, you can calculate:
% of loss in cutting = 0.100 kg ÷ 2.5 kg
= 0.04
= 4%
% of trim = 0.250 kg ÷ 2.5 kg
= 0.1
= 10%
% of usable meat = 1.300 kg ÷ 2.5 kg
= 0.52
= 52%
Note: The percentage of usable meat is an important concept. It is often referred to as the yield percentage or yield factor. It will be looked at in some detail later in this chapter.
• Value per kg: This column of Figure 12 lists the value of the parts per unit of weight. These values are based on what it would cost to purchase similar products from a butcher shop. The tidbits are quite valuable although they are too small to be used as medallions. They might be used, however, in stews or soups. Notice that no value is given to any weight lost in cutting.
• Total value: This is determined by multiplying the value per kg column by the weight column. This has to be done carefully as the units must match. For example, the temptation is to simply multiply the weight of the fat and gristle (850 g) by \$0.20 and get \$170 instead of converting the grams into kilograms (850 g = 0.850 kg) and then multiplying to give the actual value of \$0.17.
The entry for the “Usable Meat” in the total value column is determined by subtracting the value of the breakdown parts from the total cost of the pork loin (\$30.35). The total cost is found by multiplying the weight of the whole piece (2.5 kg) by the value per kg (\$12.14).
Example 15: The total value of usable meat equation
total value of usable meat = total cost – total value of breakdown parts
= \$30.35 − (\$0.17 + \$1.87)
= \$30.35 − (2.04)
= \$28.31
• Cost of usable kg (or EP cost): cost of usable kilogram is determined by dividing the total value of the usable meat by the weight of the usable meat as measured in kilograms (see below).
Example 16: Cost of usable kg (or EP cost) equation
cost per usable kg = total value of usable meat ÷ kg weight of usable meat
= \$28.31 ÷ 1.3 kg (remember 1300 g = 1.3 kg)
= \$21.78
Notice the difference between the wholesale cost (\$12.14 kg) and the cost of usable meat (\$21.78). This difference shows why the basic formula for determining standard portion costs will not work with meat.
• Portion size and portion cost: The last two columns in Figure 12 show portion size and portion cost. Portion size is determined by management; in this example, individual portions of the pork loin weigh 250 g (or 0.250 kg).
Example 17: The portion cost is determined by multiplying the cost of a usable kg by the portion size.
That is,
portion cost = portion size × cost of usable kg
Using the correct units is very important. The portion size should be converted into kilograms as the cost per usable kg has been found.
Example 18: Portion size equation
portion cost = portion size × cost of usable kg
= 0.250 kg × \$21.78/kg
= \$5.44
• Cost factor: If the price of pork loin changes, the monetary values entered on the meat cutting yield sheet become invalid. This column in Figure 12 attempts to reduce the chance that all this work is suddenly for naught. The cost factor will probably not change drastically but the wholesale cost of purchasing the meat might. By having a cost factor on hand, you can quickly apply it to the wholesale price of the purchased product and determine what an appropriate selling price should be. The cost factor per kilogram is determined by dividing the cost per usable kg by the original cost per kilogram (see below).
Example 19: Cost factor equation
cost factor per kg = cost per usable kg ÷ original cost per kg
In this example,
cost factor per kg = cost per usable kg ÷ original cost per kg
= \$21.78 ÷ \$12.14
= 1.79
This cost factor can be used to find the cost of a usable kg if the wholesale cost changes with the following formula.
Example 20: Finding the cost of usable kg if wholesale cost changes
new cost of usable kg = cost factor per kg × new wholesale cost
For example, if the cost of pork loin should rise to \$13.00 a kilogram from the \$12.14 per kilogram given on the cutting yield test sheet, the new cost per usable kg can be quickly calculated:
new cost of usable kg = cost factor per kg × new wholesale cost
= 1.79 × \$13.00
= \$23.27
Notice the size of the increase is in usable kg cost. The wholesale cost rose by (\$13.00 − \$12.14) \$0.86 a kg, but the new cost of usable meat rose by \$1.49 a kg.
Example 21: Cost factor per portion equation
The cost factor per portion is found by multiplying the portion size by the cost factor per kilogram. In this example,
cost factor per portion = portion size × cost factor per kg
= 0.250 kg × 1.79
= 0.45
The cost factor per portion is important because it can be used to find the cost per portion from the wholesale cost of meat. This is done by multiplying the two quantities. For example, if the wholesale price of pork loin should rise to \$13.00 a kg, the portion cost will become:
new portion cost = cost factor per portion × new wholesale cost
= 0.45 × \$13.00
= \$5.85
The cost factor per kilogram and the cost factor per portion are the most important entries on a meat cutting yield test as they can be used to adjust to changing wholesale costs.
Today, the meat cutting yield test is losing some of its popularity because of the introduction of pre-portioned meats. But there remain several benefits to performing meat cutting tests:
• Exact costs are determined so menu pricing can be more accurate.
• Tests done periodically verify that the meat wholesaler is providing meat to stipulated specifications. If the amount of trim and waste rises, so do food costs.
• By comparing the results from two or more wholesalers who have provided the same sample cuts, a critical evaluation can be done to determine which one is supplying the better meat.
• Comparing yields between people doing the cutting will tell you who is being the most efficient.
• Since individual pieces of meat or fish may vary slightly, doing yield tests on several of the same item and taking an average will give you the best idea of your standard yield. | textbooks/workforce/Food_Production_Service_and_Culinary_Arts/Basic_Kitchen_and_Food_Service_Management_(BC_Campus)/03%3A_Food_Costing/3.02%3A_Yield_Testing.txt |
Some meats cannot be accurately portioned until they are cooked. This applies particularly to roasts, which shrink during cooking. The amount lost due to shrinkage can be minimized by incorporating the principles of low-temperature roasting, but some shrinkage is unavoidable.
The cooking loss test serves the same function as the meat cutting yield test. Their similarities and differences will become evident in the discussion below. Figure 13 shows a sample cooking loss test form.
Figure 13: Cooking Loss Test Form
Item: Leg of Lamb
Portion: 125 g
Cost factor: 0.2931
Number cooked: One
Time: 2 hours and 30 minutes
Temperature: 175°C
Breakdown Weight % of Total Weight Value (per kg) Total Value EP Cost (per kg) Portion Size Portion Cost Cost Factor (per kg) Cost factor per portion
Original weight 3750 g 100% \$6.50 \$24.38
Trimmed weight 2850 g 76.00% \$24.38
Loss in Trimming 900 g 24% 0
Cooked Weight 2350 g 62.67% \$24.38
Loss in Cooking 500 g 13.33% 0
Bones and Trim 750 g 20% 0
Saleable Weight 1600 g 43.00% \$24.38 \$15.24 125 g \$1.91 2.3446 0.2931
When using a cooking loss test form, note the following, referring to Figure 13:
• The form specifies the time and temperature of the roasting.
• The column headings are similar to the column headings on the meat cutting yield test form (Figure 12), as you are measuring similar things.
• The first line in Figure 13 lists the weight and wholesale cost of the roast (total value).
• The trimmed weight is the weight of the roast that is placed in the oven. Some fat and gristle has been trimmed off in the kitchen. In the example, about 900 g have been trimmed. Technically, if the trim has some value, it should be used to reduce the total value of the roast. However, for simplicity it is ignored in this example.
• After cooking for 2 hours and 30 minutes (the time stated on the test form), the roast is weighed and the cooked weight is entered on the form.
• The weight loss in cooking is determined by subtracting and the value entered on the form.
• The cooked roast is then deboned and trimmed. The weight of this waste is recorded.
• The weight of the remaining roast is determined. This is the amount of cooked roast you have available to sell and which can be divided into portions.
• Notice that the total value (that is, the cost) of the roast remains the same throughout the process. Only the weight of the roast changes.
• The percentage of total weight figures are calculated in the same way they were determined in Figure 12.
• The cost of usable kg is determined by dividing the saleable weight into the total value of the roast.
• Portion size is determined by restaurant managers, and the portion cost is calculated by multiplying the cost of usable kg and the portion size. This is the same procedure used to determine portion cost on the meat cutting yield test form.
• The cost factor per kg is the ratio of the cost of usable kg and the original value per kg.
Example 22: Equation
cost factor per kg = cost of usable kg ÷ value per kg
= \$15.24 ÷ \$6.50
= 2.3446
• The cost factor per portion is again found by multiplying the cost factor per kg by the portion size.
As with the meat cutting yield test, the most important entries on the cooking loss test sheet are the portion cost and the cost factor per kg as they can be used to directly determine the portion and kilogram costs if the wholesale cost unit price changes.
Yield percentages are the ratio to total weight values found for usable meat on the meat cutting yield test sheet and the saleable weight found on the cooking loss test. Once found, yield percentages (or yield factors as they are sometimes called) are used in quantity calculations.
The general relationship between quantity and yield percentage can be seen in the following equation:
quantity needed = (number of portions × portion size) ÷ yield percentage
Example 23: Equation
Find the quantity of pork loin needed to serve 50 people 250-g portions if the yield percentage is 52% as in Figure 12. The solution is:
quantity needed = (number of portions × portion size) ÷ yield percentage
= (50 × 0.250 kg) ÷ 52%
= 12.5 kg ÷ 0.52
= 24.03 kg
You need just over 24 kg of untrimmed pork loin to serve 50 portions of 250 g each.
The yield formula can be restated in other ways. For example, if you needed to find how many 125 g portions of lamb can be served from 12 kg of uncooked lamb given a yield factor of 43%, you could use the following procedure:
Example 24: Equation
number of portions = (quantity on hand × yield percentage) ÷ portion size
= (12 kg × 0.43) ÷ 0.125 kg
= 5.16 kg ÷ 0.125
= 41.28
As with the inventory sheets, using a spreadsheet to help calculate the yields and factors is helpful. Some sample tools are provided in the Appendix. | textbooks/workforce/Food_Production_Service_and_Culinary_Arts/Basic_Kitchen_and_Food_Service_Management_(BC_Campus)/03%3A_Food_Costing/3.03%3A_Cooking_Loss_Test.txt |
Monthly food costs are determined by taking a monthly physical inventory of food stock, evaluating the inventory, and then adjusting the valuation to more accurately reflect the cost of food consumed.
The basic formula to determine the cost of food in a month is:
cost of food = opening inventory + purchases − closing inventory
Example 25: Calculating food cost
For example, if opening inventory is \$10 000 and purchases amount to \$7500, and the closing inventory (which is also the beginning inventory for the next month) is \$9000, then the basic cost of food is:
cost of food = opening inventory + purchases − closing inventory
= \$10 000 + \$7500 − \$9000
= \$17 500 − \$9000
= \$8500
The value of the inventory is the critical component in deriving an accurate cost figure from the basic formula given above.
The information needed to accurately assess the value of inventory is obtained from daily receiving reports (that is, purchases), perpetual inventory cards (that is, inventory records that indicate what is in storage and what supplies have been removed from storage at the request of the kitchen), and by doing a physical inventory.
Adjusting (Credits and Transfers) the Evaluation of Food Costs
Some food inventory is used for purposes other than generating direct sales. For example, if employees are fed or are given a significant discount, the food cost for these meals is usually subtracted from the total found by the basic food cost formula. The cost of employee meals should not be ignored, but it might better be considered a labour cost and not a true food cost.
Promotional expenses are also subtracted from the basic cost of food figure. These include “2 for 1 specials,” coupon discounts, and other promotions. The deduction made, remember, is not the menu price but the actual cost of the food to the operation. Again, this expense cannot be ignored, but should be included as a different type of operating expense.
In some restaurant and hotel operations, food is transferred to the bar where it is served as as hors d’oeuvre to promote the sale of alcoholic beverages. This is really an expense of the bar and should not be considered a kitchen expense. The cost of transferred food should be deducted from the basic food cost figure. This cost is best considered a promotional expense borne by the bar.
Other adjustments might have to be made to the gross cost of food, depending on how the individual restaurant operates. For example, in some cases, the kitchen might acquire wine or liquor from the bar for cooking or flambéing, and that should be considered a food cost.
Example 26: Net cost of food for an operation
In general, the net cost of food for an operation is summarized in the following equation:
net food cost = basic food cost − (employee meal cost + promotional expenses + transferred out food costs) + transferred in food costs
Food Cost Report
A monthly food cost report is often required by management. The basic form of the food cost report tends to be a comparison of food cost percentages. Percentages are used instead of actual net food cost as such costs vary according to sales. Percentage food cost tends to remain constant regardless of sales.
Example 27: Food cost percentages
Food cost percentages are computed by using the following equation:
food cost percentage = net food cost ÷ food sales
For example, if net food costs are \$5500 and food sales were \$13 700, then food cost percentage = net food cost ÷ food sales
= \$5500 ÷ \$13 700
= 0.401
= 40%
The food cost report often compares the current month’s results with the food cost percentage of the previous month or the cost percentage of the same month a year ago (Figure 14). Management can then decide if monthly food costs are under control.
Figure 14: Comparative monthly sales
Food Cost Report
Date Food Costs Food Sales Food Cost Percentage
Last month \$8000 \$32 000 25.0%
Previous month \$8500 \$30 000 28.3%
Same month last year \$9500 \$31 000 30.6%
Other costs must also be taken into account to properly understand where the food income dollar is going within the operation. In some restaurant businesses, the breakdown of expenses is recorded in a monthly percentage costing report on a form as shown in Figure 15.
Figure 15: Percentage costing report
Year:
Month:
Percentage Costing Report
Amount % Remarks
Total sales
Food costs
Labour cost
Rent/Lease
Other operating expenses
Total cost
Profit
The cost percentages are determined by dividing the individual costs by the total sales. Near the beginning of each month, the percentage costing form of the previous month is completed and compared to the results on past forms.
Food costs can be further analyzed by investigating the costs and percentage of total food cost of individual categories of food items, as shown in the example in Figure 16.
Figure 16: Food cost analysis report
Food cost analysis report
Item Cost (October) % of Total Cost (October) Cost (November) % of Total Cost (November)
Meat \$ 874.70 27.1% \$ 811.12 28.2%
Fish \$ 264.67 8.2% \$ 184.08 6.4%
Poultry \$ 390.55 12.1% \$ 330.77 11.5%
Dairy \$ 532.56 16.5% \$ 440.07 15.3%
Eggs \$ 203.34 6.3% \$ 212.85 7.4%
Bakery \$ 129.11 4.0% \$ 143.82 5.0%
Produce \$ 254.99 7.0% \$ 238.73 8.3%
Dry goods \$ 490.60 15.2% \$ 414.19 14.4%
Beverages \$ 87.15 2.7% \$ 100.67 3.5%
Total cost \$3227.67 100% \$2876.30 100%
Total sales \$9143.50 \$8560.35
Food cost % 35.3% 33.6%
An important line in the chart shown in Figure 16 is the last one, “Food cost %.” In the example, total sales have dropped in November, but the food cost percentage has also decreased. As long as labour costs have not changed markedly from October, the food cost percentages suggest that this operation copes well with changing sales and is probably in a strong financial position even though demand is down. Sales have dropped by 6.4%, but food costs have decreased by 10.9%.
Describe Daily Food Cost Controls
A month is a long time between reports, particularly if the reports are financial in nature and will determine if the operation is keeping costs under control. If costs are not controlled, the business is likely to fail.
Daily food costs are calculated much the same way as the basic monthly food costs and the monthly net food costs. However, the inventory used is the actual amount of money that is spent daily on direct supplies or directs (that is, supplies that are purchased and used that day, such as breads and dairy products in many operations) and the value of stores used (that is, the value of the materials already on hand that have been requested and received from the storage area).
Example 28: Basic daily food costs
Basic daily food costs can be expressed as:
daily food costs = cost of direct supplies + cost of stores
The daily food costs found by using the basic formula can be adjusted in much the same way as the basic monthly food cost. That is,
net daily food costs = daily food cost − (employee meal costs + promotional expenses + transferred out food costs) + transferred in food costs
Cumulative Cost Records
The easiest way to keep track of daily food costs is to use a form like the one shown in Figure 17. On this form, the cost of direct supplies, the cost of stores, total costs today, cumulative cost for the month, sales for the day, cumulative sales for the month, cost percentages for the day, and cost percentages for the month can be entered. Note that the form does not take into account transfers.
Some POS systems have this feature and can be used to track daily food costs.
Figure 17: Daily cumulative food cost record
Daily cumulative food cost record
Date Stores Directs Cost Today Cost to Date Sales Today Sales to Date Cost % Today Cost % to Date
A new form is started each month. Nothing is carried forward from month to month. The month-end totals should be close to the figures obtained using other monthly food cost procedures, such as those calculated after doing a physical inventory.
The information needed to fill in the food cost record are the daily food purchase reports for direct costs, copies of requisitions for stores, and the daily sales figures.
The following example explains how to fill out the form.
Example 29
On the first day of the month, \$35.00 was spent on directs, \$102.00 on stores, and total sales were \$360.00. On the second day of the month, \$12.50 was spent on directs, \$95.00 on stores, and sales were \$345.00. On the third day, \$30.00 was spent on directs, \$99.50 on stores, and total sales for the day were \$310.50.
• On the first day, the date is inserted.
• Next to the date in Column B the cost from stores is entered.
• In Column C the cost of directs is entered.
• In Column F the days sales is entered.
• Column G is the same as F or is left blank.
• Column H is determined by dividing Column D by Column F.
• Column I is blank or has the same value as Column H.
Columns A, B, C, D, F, and H for the second day are filled in with the cost and sales information given. Column E is the sum of the previous day’s value in Column E and today’s value in Column D. Similarly, Column G is the sum of the previous day’s Column G and today’s Column F. The value of Column I is determined by dividing Column E by Column G.
The costs and sales of the rest of the month are entered in the same way as on the second day. The final result is shown in Figure 18.
Figure 18: Daily cumulative food cost record
A B C D E F G H I
Date Stores Directs Cost Today Cost to Date Sales Today Sales to Date Cost % Today Cost % to Date
10/1 \$102.00 \$35.00 \$137.00 \$137.00 \$360.00 38% 38%
10/2 \$95.00 \$12.50 \$107.50 \$244.50 \$345.00 \$705.00 31% 35%
10/3 \$99.50 \$30.00 \$129.50 \$374.00 \$310.50 \$1015.50 42% 37%
The daily cumulative food cost record will quickly indicate if daily food costs are getting out of hand. A single bad food cost percentage day may not be anything to worry about as supplies charged against that day may not have been entirely used that day. For example, directs might be received only twice a week and so on those days, costs will look high. However, the directs might be used over a period of two or three days. Changes in the pattern of the cost percentages may indicate problems.
Daily Reports
The daily report is usually a simple statement containing total food costs, total food sales, and cost percentages. The form can contain other columns that indicate cumulative totals or totals for the same day a month ago. A sample form is shown in Figure 19.
Figure 19: Daily report
Date: 10/3
Daily Report
Today Month to Date Year to Date Last Year to Date
Food cost \$129.50 \$2025 \$32 600 \$31 750
Food sales \$310.50 \$4330 \$92 500 \$85 750
Food cost % 42% 38% 35% 37%
Small variations will show up in the daily reports and are to be expected. However, if changes seem to be part of a pattern, managers who receive the daily reports will have a maximum of warning time to remedy the possible problem.
Causes of cost percentage overruns include:
• Short weights and counts on deliveries
• Waste in the kitchen
• Theft
• Poor recipe control
• Improper costing and menu pricing
• Poor use of leftovers
In many food service operations, daily food costs are broken down into the daily costs of individual categories of raw food items. A typical form is shown in Figure 20.
• The “Desired %” line values are determined by the restaurant analyzing the daily food cost percentages of the individual groups of food over a period of time. In the example, the total of these desired percentages is 40%. These percentages are calculated by dividing the cost of each food category by the total food cost.
• At the “Total to Date” line, trial cost percentages are determined so that the actual cost percentages of individual categories can be compared to the desired percentages. If an area is excessively high, then an investigation should be made to determine the causes.
Figure 20: Daily food cost control sheet
Daily food cost control sheet
Meat Fish Poultry Dairy Eggs Bakery Produce Dry Goods Beverages Daily Food Cost Daily Sales Daily Food Cost % To Date Food Cost %
Desired % 10% 3.20% 4.50% 6.00% 2.50% 2.10% 3.20% 6.50% 2.00% 40%
Oct 1 \$67.15 \$22.38 \$28.54 \$27.95 \$11.19 \$12.87 \$14.50 \$28.50 11.75 \$224.83 \$468.40 48%
Oct 2 \$61.12 \$26.74 \$30.56 \$45.84 \$16.04 \$17.57 \$26.74 \$57.3 \$13.75 \$295.66 \$721.12 41%
Oct 3 42.03 15.75 21.54 36.78 13.1 18.76 18.39 37.3 6.5 210.15 550.13 38%
Oct 4 85.39 25.17 32.6 5.03 23.25 23.45 27.95 32.15 15.53 310.52 889.49 35%
Oct 5
Total to date \$255.69 \$90.04 \$113.24 \$115.60 \$63.58 \$72.65 \$87.58 \$155.25 \$47.53 \$1041.16 \$2629.14 40%
Per cent to date 9.73% 3.42% 4.31% 4.40% 2.42% 2.76% 3.33% 5.90% 1.81%
Variance −0.27% 0.22% −0.19% −1.60% −0.08% 0.66% 0.13% −0.60% −0.19% 0%
Key Takeaway
Managing food costs is one of the most critical aspects of running a successful food service operation. Having procedures and tools in place to track sales and costs help to identify any possible issues and create the opportunity to remedy the problem before it gets out of control. | textbooks/workforce/Food_Production_Service_and_Culinary_Arts/Basic_Kitchen_and_Food_Service_Management_(BC_Campus)/03%3A_Food_Costing/3.04%3A_Monthly_Food_Costs.txt |
Although you likely have a target overall food cost in your establishment, not every menu item will carry exactly the same food cost percentage. Some items are more costly than others, but most establishments will have a range of prices that all the menu items fit into. Consequently, it is important to balance the menu so that the low and high food cost items work together to help you reach your target food cost. This process is called menu engineering. Menu engineering means balancing the high and low food cost items; it also includes strategically featuring or promoting items to help reach your targets.
Calculating Menu Item Costs
The cost per portion derived from yield tests done on the main ingredient of a menu item usually represents the greatest part of the cost of preparing the item (see the section above on yield tests for more information).
However, of equal importance is the portion cost factor. For example, the portion cost factor can be used to determine the cost of a portion of the main ingredient regardless of the price of the meat (which is often the main cost factor) charged by the supplier as long as the restaurant’s preparation of the meat remains unchanged. The cost per portion is determined by multiplying the portion cost factor by the packing house’s price per kilogram (or pound).
Quite often the cost per portion of the main ingredient is used by itself to determine the selling price of a menu item. This works well with items on an à la carte menu as the basic main ingredient (such as a steak) is sold by itself and traditional add-ons (such as a baked potato and other vegetables) are sold separately.
As discussed earlier in this book, in many cases, some of the components will be the same, so a basic plate cost can be used to add to the cost of the main protein to get a total cost for the dish.
In dishes where the main ingredients are not sold as entities but as part of a prepared dish, the cost of all the items in the recipe must be determined to find an accurate portion cost price. In this case, a recipe detail and cost sheet is used to determine the cost price of menu items. (Refer back to the section on costing individual menu items for more information.)
Once the potential cost of a menu item is determined, the selling price of the item can also be calculated by using the food cost percentage.
Food Cost Percentages
As you may recall, food cost percentage is determined by dividing the portion cost by the selling price:
Example 30: Food cost percentages
food cost percentage = portion cost ÷ selling price
If the portion cost is \$4.80 and the selling price is \$14.00, the food cost percentage is:
food cost percentage = portion cost ÷ selling price
= \$4.80 ÷ \$14.00
= 0.34285
= 34.285%
= 34% (rounded off)
Another way of expressing the food cost is as a cost mark-up.
Example 31: Cost mark-up
The cost mark-up is determined by reversing the food cost percentage equation:
cost mark-up = selling price ÷ portion cost
The cost mark-up can also be determined by dividing the food cost percentage into 1. The equation then becomes:
cost mark-up = 1 ÷ food cost percentage
In the example above, where the portion cost is \$1.20 and the selling price is \$3.50, the cost mark-up can be solved in the following ways:
cost mark-up = selling price ÷ portion cost
= \$14.00 ÷ \$4.80
= 2.9166
= 2.92
or cost mark-up = 1 ÷ food cost percentage
= 1 ÷ 34.285%
= 1 ÷ 0.34285
= 2.91674
= 2.92
The cost mark-up can be used to determine a selling price when a portion cost is known by multiplying the cost mark-up and the portion cost:
Example 32: Determine a selling price
selling price = portion cost × cost mark-up
For example, if the ingredients for a portion of soup costs \$1.05 and the restaurant has a cost mark-up of 3.6, the menu price of the soup is:
selling price = portion cost × cost mark-up
= \$1.05 × 3.6
= \$3.78
The restaurant would charge at least \$3.78 for the menu item if it wants to keep its mark-up margin at 3.6, which is about a 28% food cost percentage. This price might be adjusted because of competition selling the same item for a different price, price rounding policies of the restaurant or the whims of management. For example, many restaurants have prices that end in 5 or 9 (such as \$4.99 or \$5.95). Prices on such menus tend to be rounded to the nearest number ending in 5 or 9. No matter what the final menu price is, at least a base price has been established.
The problem with the above approach is it doesn’t explain how to select a food percentage or a selling price from which to derive the percentage. In many cases, the food percentage is based on past experiences of the manager, or by a supposed awareness of industry averages. For example, many people simply set their food percentage at 30% and never work out a more appropriate figure. Similarly, the selling price of a menu item is often the product of guessing what the market will bear: \$4.50 for a bowl of soup may seem like a good deal or as much as a reasonable person might pay in that restaurant. Unfortunately, none of these methods takes into account the unique situations affecting most restaurants.
A more accurate way of computing a target food cost percentage is to estimate total sales, labour costs, and hoped-for profits. These figures are used to determine allowed food costs. The total of projected food costs is divided by the projected sales to produce a food cost percentage. The food cost percentage can be turned into a mark-up margin by dividing the percentage into 1, as shown above.
Example 33
For example, to determine the food cost percentage of a restaurant that has projected sales of \$10 000 and labour costs of \$6000, overhead of \$1000, and a goal of before-tax profits of \$500, the following procedure is used:
food costs = sales − (labour costs + overhead + profit)
= \$10 000 − (\$6000 + \$1000 + \$500)
= \$10 000 − (\$7500)
= \$2500
food percentage = food costs ÷ sales
= \$2500 ÷ \$10 000
= 0.25
= 25%
mark-up margin = 1 ÷ food percentage
= 1 ÷ 25%
= 1 ÷ 0.25
= 4
In this example, the menu prices would be determined by multiplying the portion costs of each item by the mark-up margin of 4. Adjustments would then be made to better fit the prices to local market conditions.
If the application of the derived mark-up margin produces unreasonable prices, then one or more of the projected sales, labour costs, overhead, or profits are probably unreasonable. The advantage of using this system is that it points out (but does not pinpoint) such problem assumptions early in the process.
A similar approach uses a worksheet as shown in Figure 21.
In the middle section of the worksheet in Figure 21, a food cost percentage is determined by subtracting other known cost percentages (i.e., operating costs, labour cost, and profit wanted) from 100%. One divided by the food cost percentage determines the mark-up margin. Food costs are then determined in the bottom half of the sheet and a menu price derived by multiplying the total cost by the mark-up margin.
In this pricing method, a “profit wanted” percentage is added to the cost of each menu item. This builds some potential profit into the menu prices. If you were to price everything according to costs only, the restaurant would only ever be able to break even and never turn a profit.
Contribution Margins
On the surface, it seems that the lower the food cost, the more room there is for profit. In one sense this is true, as the percentage profit is obviously greater for an item that has a food cost percentage of 25% (or 75% percentage profit) than an item that has a food percentage cost of 45% (or 55% percentage profit). However, in terms of monetary profit, the issue is not that straightforward. What has to be determined is how much money the menu item generates. This calculation involves finding the contribution margin of each item.
Example 34: Contribution margin
Contribution margin is determined by subtracting the cost from the selling price. An item that costs \$2.00 to make and sells for \$3.00 has a contribution margin of:
contribution margin = selling price − cost price
= \$3.00 − \$2.00
= \$1.00
Consider the contribution margin of two menu items that have different food costs and food cost percentages shown in Figure 22.
Figure 22: Contribution margin
Contribution margin
Item Food Cost Selling Price Food Cost % Contribution Margin
Chicken \$4.50 \$16.50 27% \$12.00
Steak \$9.00 \$24.00 38% \$15.00
In terms of percentage profit, the chicken is higher. However, in terms of money in the till, the steak creates more money that can be used to pay bills. The key to a good menu is not necessarily to just keep food cost percentages low; it is to also to keep contribution margins high.
Balancing the Menu to Achieve Targets
Menu Analysis
A basic menu analysis determines how often each item on the menu is sold. This basic statistic can be used with cost percentages, menu prices, and sales values to make generalizations about the relative value of each menu item. Figure 23 shows a menu analysis worksheet for a lunch menu. Most POS systems can generate this type of information at the end of a shift, day, week, or month.
Figure 23: Menu analysis worksheet
Menu analysis worksheet
A B C D E F G H I J
Menu Item Total Sold Menu Price Portion Cost Food Cost % Portion C.M.[1] Total Food Sales Total Food Cost Total C.M. C.M.%
Hamburger 12 \$10.95 \$2.75 25% \$8.20 \$131.40 \$33.00 \$98.40 24%
Cheeseburger 8 \$11.95 \$4.25 36% \$7.70 \$95.60 \$34.00 \$61.60 15%
BLT sandwich 10 \$11.95 \$3.75 31% \$8.20 \$119.50 37.50 \$82.00 20%
Ham sandwich 5 \$10.95 \$3.50 32% \$7.45 \$54.75 17.50 \$37.25 9%
Fried chicken 4 \$14.95 \$5.25 35% \$9.70 \$59.80 \$21.00 \$38.80 9%
Clubhouse 6 \$12.95 \$4.00 31% \$8.95 \$77.70 \$24.00 \$53.70 13%
Steak sandwich 5 \$15.95 \$7.25 45% \$8.70 \$79.75 36.25 \$43.50 10%
Totals 50 \$618.50 \$203.25 \$415.25
The statistics provided in a menu analysis have several uses. For example, the total sold statistics can be used to predict what future sales numbers will be. This information is valuable for ordering supplies and organizing the kitchen and kitchen staff to produce the predicted number of items.
Even more important than popularity is the contribution margin of each item. Often an average contribution margin is found and compared with the contribution margin of individual items.
Example 35: Average contribution margin
The average contribution margin in the example above is found by dividing the total contribution margin (total of Column I) by the number of sales (total of Column B):
average margin = total margin ÷ number of sales
= \$415.25 ÷ 50
= \$8.31
The contribution margin for each item is found by subtracting the cost of the item from the selling price. In the example in Figure 23, the contribution margins are given in Column F.
Some decisions can be made comparing items:
• The hamburgers, cheeseburgers, BLTs, and ham sandwiches are below the average contribution margin. The first three items are good sellers and account for over half of the sales (30/50 = 60%) and they may be able to pull their weight by slightly increasing their prices. By adding \$0.50 to the menu price of each of these items, they would each have a contribution margin above or close to \$8.31.
• The ham sandwich is significantly lower than the average margin and is also low in sales. It might be best to drop this item from the menu and replace it with something else.
• The fried chicken has a good contribution margin but its sales are a little on the low side. To increase sales, the chicken might be given more prominence on the menu or might be offered as part of a special with a small salad for a slight increase in price. As long as the additions have a reasonable food cost percentage and are inexpensive compared to the portion cost of the chicken, the increase in sales should have a positive impact on the total contribution margin (the values in Column I).
The type of menu analysis must be tempered with common sense. Because averages are used to determine an acceptable margin or level of sales, some menu items will automatically be under the average just as some will have to be above the average. If items that are under the average are replaced, the next time a menu analysis is done there will be a new average and other items under that average. Taken logically, your menu options will run out before you have every item being exactly at the average!
Given that menu items are usually broken down into categories, this type of analysis is most effective when comparing similar items. An analysis of all of the desserts or starters to compare their margins is much more effective than comparing the margin of a dessert against a lobster dinner, which by the very nature of its price and cost will always have a higher contribution margin.
Profitability
You want to sell menu items that have a high margin of profitability. The relative profitability of an item is calculated by comparing its contribution margin to the average contribution margin (ACM) of all items. The contribution margin is the selling price of a menu item minus the standard food cost of the item. This is the amount that the item contributes to the labour cost, other costs of doing business, and profit. The ACM equals the total contribution margin divided by total numbers of items sold. Profitable items have a contribution margin equal to or higher than the ACM.
Desserts and appetizers may have lower contribution margins than entrées. This is because these items generally have lower prices and cannot contribute the same dollar value of contribution margin, even though their food cost percentage may be lower than entrée items. Also, the restaurant may wish to tempt patrons to add these items to their purchase, increasing the average cheque size. If you can sell more to an individual guest, you increase the revenues without increasing the labour costs and other costs to the same extent.
For example, if the customer orders and appetizer before the entrée, he or she does not take up any more time in the restaurant (that is, the customer does not decrease seat turnover) because the appetizer is served and eaten during the normal waiting time for preparing the main dish. As well, the additional labour of the server is minimal because even without ordering an appetizer service may still be needed to provide additional bread or refill water glasses. Thus, the sale of the appetizer will increase the profitability of the restaurant even though the contribution margin is not as high.
Desserts may also have a low contribution margin. Often desserts are purchased ready-made (e.g., cakes and cheesecakes). There may be little labour cost in serving these items so the overall contribution of the dessert item to profitability is high.
Items that require little preparation (that is, have a low labour cost) may still generate a significant contribution to margin even when their food costs are higher. Even if the food cost of the item was very high and the CM low, you would want to keep this item because the combined labour cost and food cost is low. Thus the amount this item contributes to the fixed cost of the business is high.
Potential Profitability of Menu Items
To determine the potential profit in a menu item, you must have a good idea of the potential cost of producing the item. Pre-costing the menu means you determine the cost of producing every item on the menu under ideal conditions. The assumption is that cooks will follow directions, the portions will be accurately measured, and all the portions will be sold. The results are the optimum costs; in reality costs could be higher.
Popularity
Another factor to consider when reviewing your menus is the popularity of an item. Popularity is determined by comparing sales of items to expected popularity. The expected popularity is the predicted menu mix (sometimes called the sales mix) if each of the menu items in a category were equally popular.
An example is provided in Figure 24, which lists seven appetizers. The expected popularity would be 100% divided by 7 (the number of menu items) or 14.3%. Menu analysis assumes that popular items have sales of 70% or more of the expected popularity. In the example, appetizers would have to exceed 10% (70% of 14.3%) of appetizer sales in order to be considered popular. Which of the items are popular?
Figure 24: Menu analysis worksheet
Figure 24: Menu analysis worksheet
Menu Item Total Sold Menu Price Portion Cost Food Cost % Portion C.M. Total Food Cost Total Food Sales Total C.M. C.M.%
Thai Wings 31 \$6.75 \$1.93 28.59% \$4.82 \$59.83 \$209.25 \$149.42 4.63%
Dry Ribs 211 \$6.75 \$1.72 25.48% \$5.03 \$362.92 \$1,424.25 \$1,061.33 31.54%
Nachos 71 \$6.95 \$1.53 22.01% \$5.43 \$108.63 \$493.45 \$384.82 10.61%
Calamari 19 \$7.50 \$2.23 29.73% \$5.27 \$42.37 \$142.50 \$100.13 2.84%
Soup and Salad 78 \$5.95 \$1.55 26.05% \$4.40 \$120.90 \$464.10 \$343.20 11.66%
Thai Salad 129 \$6.45 \$1.68 26.05% \$4.77 \$216.72 \$832.05 \$615.33 19.28%
Cajun Caesar 130 \$6.95 \$1.76 25.32% \$5.19 \$228.80 \$903.50 \$674.70 19.43%
Total Appetizer 669 ACM = \$4.98 \$1,140.70 \$4,469.10 \$3,328.93 100.00%
You can see at a glance that Dry Ribs is the most popular appetizer, followed by Thai Salad and Cajun Caesar. Nachos and Soup & Salad fall just slightly over the 10% boundary. Thai Wings and Calamari show dismal results in terms of popularity with only 4.63% and 2.84% of appetizer sales.
Sales of menu items are analyzed to put menu items in four categories:
• Popular and profitable
• Popular but not profitable
• Not popular but profitable
• Neither popular nor profitable
Figure 25 displays graphs the popularity of the appetizers from the example over these four categories. The graph shows popularity on the vertical axis and contribution margin on the horizontal axis. A line is drawn vertically to indicate the ACM and horizontally to show 70% of expected popularity. This allows you to see at a glance which category an item falls into: A) Less popular and profitable, B) popular and profitable, C) unpopular and unprofitable, and D) Unpopular and profitable.
The graph shows that Thai Wings and Calamari were very unpopular menu items, but it also provides information on profitability. Thai Wings has a contribution margin that is lower than the ACM for appetizers. Calamari has a contribution margin that is higher than the ACM.
Computer programs may automatically calculate contribution margins and popularity. The information may be presented in tables or spreadsheets as shown above, or in a four-box analysis, with less detail, as shown in Figure 26.
Figure 26: Four-box analysis of appetizer items
Figure 26: Four-box analysis of appetizer items
Unprofitable Profitable
Popular Thai Salad, Soup and Salad Dry Ribs, Cajun Caesar, Nachos
Unpopular Thai Wings Calamari
Menu Revisions
Popular and profitable items are ones you want to maintain on your menu. Maintain the specifications of the item rigidly. Do not change the quality of the product served. Feature the item in a prominent location on the menu. You want to sell this item, so make sure that customers see it. Have servers suggestively sell the item. For example, when asked for suggestions, they could say, “You may want to try our Linguine Chicken. It is very popular. It has a cream sauce with lots of fresh basil.” Test the possibility of increasing prices by raising the price slightly.
If an item is popular but not profitable, you want to see if you can increase the contribution margin without reducing its popularity. Increase prices carefully and gradually. If the item is attractive because of its high value, it may still be a good value after a price increase. You could also increase the contribution margin by reducing the cost of the accompaniments. For example, you might substitute less costly vegetables. You might also try to reduce costs by decreasing the portion size. If you are unable to improve the item’s popularity, you may want to relocate it to a lower profile part of menu. If the item has a very low labour cost, you may be able to justify the lower contribution margin because less revenue is needed to compensate for the labour cost.
Not popular but profitable items are often a puzzle. You want to sell these items, but your challenge is to encourage the guests to buy them. Shift demand to these items by repositioning them on the menu. Encourage servers to suggestively sell these items. Consider decreasing the price slightly or adding value by offering a larger portion size, more expensive accompaniments or garnishes. However, you need to be cautious so that you do not change the item into a popular but unprofitable item.
Items that are neither popular nor profitable are obvious candidates to remove from the menu. They are not pulling their weight. The only time such an item might be left on the menu is if it provides an opportunity to use leftovers and has low labour costs associated with its preparation.
Using Specials and Feature Items
Another way to balance the menu is by using daily specials and feature items. For example, assume you have been tracking your food costs using a daily food cost control sheet (refer back to Figure 20). It is halfway through the month and you are running a slightly higher than average food cost for the month so far. Choosing to run specials that have lower food costs or having the staff feature and promote the better food cost items should help to bring the targets in line by the end of the month.
Arranging Items on the Menu
Another way of engineering the menu is by strategically arranging the items on the menu. Some menus use callout or feature boxes to highlight certain items, others have pictures featuring certain menu items, and others may note an item as a house specialty. These are all ways to attract the attention of the customer, and in most cases, you will find that it is these items that sell the best. If these items also have high contribution margins and/or low food costs, they will increase profitability. Featuring the items with the lowest margins and highest food costs will have the opposite effect, and likely mean that you will not be in business for very long.
There are also some psychological reasons that things will sell on a menu. Often the most expensive or the least expensive item will not sell as well as other items on the menu because customers do not wanting to appear either extravagant or cheap in front of their guests. Using descriptions that entice the customer (e.g., “award-winning,” “best in the city”) will increase the sale of a particular item, but make sure you can deliver on the promise!
All in all, balancing the menu is something that takes time and experience to do well, but is a skill that you will need to run a profitable kitchen.
1. C.M. = Contribution margin | textbooks/workforce/Food_Production_Service_and_Culinary_Arts/Basic_Kitchen_and_Food_Service_Management_(BC_Campus)/03%3A_Food_Costing/3.05%3A_The_Principles_of_Menu_Engineering.txt |
Learning Objectives
• Describe labour cost controls
• Describe the principles of planning personnel requirements
04: Labour Costing
Controlling food costs is an important component of ensuring the profitability of your food service operation. However, food costs are only part of the picture. It is also necessary to control labour costs and forecast labour demands accurately if your business is to succeed. If you have more staff than is required, your labour costs will be too high and the company will lose money. If you have insufficient staff for a particular time period, customer service will suffer. Your goal in planning staffing needs is to match labour supply with customer volume so that you can provide quality service without excessive cost.
The food service industry is labour intensive. Technology has not replaced people with equipment. Unlike an automobile manufacturing plant, a restaurant cannot store its product until tomorrow or the next day if customers are not buying today. The same seat in the restaurant can only be sold a fixed number of times, based on the operating hours and number of turns (rate of turnover of customers). Therefore, it is critical to be able to forecast the number of customers you will have, the peak customer periods, and the staffing needed to provide service to those customers.
Sound human resource management policies can increase the productivity of staff. You must first choose qualified, interested, and trainable employees. Once these employees have been recruited, they must go through an orientation period in which they learn about the job and their responsibilities, the company’s way of doing things, and the required level of product quality. During this initial period, the employee’s productivity might be low.
Accurate job descriptions, a good orientation to the job, adequate on-the-job training, and good supervision with lots of feedback about job performance will assist employees in becoming productive as soon as possible.
4.02: Factors Affecting Working Performance
In addition to sound human resource management, other factors influence the required amount of labour. These factors include:
• Menu items
• Use of convenience foods
• Type of service
• Quantity of meals and number of meal periods
• Facility layout and design and production equipment
• Work environment and number of hours worked
Menu Items
The number and complexity of menu items affects the production hours needed. If you have a menu with many items requiring difficult production techniques, you will require more preparation time per item. If your menu consists of a limited number of items requiring minimal preparation, you will require less time.
Use of Convenience Foods
Foods prepared on site require more preparation than similar menu items made with convenience foods, such as pre-portioned meats or desserts. You can reduce your labour costs by using convenience foods. However, you must consider two other factors: convenience foods can increase your food costs and may affect the quality of your product.
The second factor – affecting the quality of the product – is not always evident. Convenience foods made with high-quality ingredients and prepared exactly as recommended by the manufacturer can provide uniform portions of very good quality.
Type of Service
A restaurant featuring complex dishes with multiple components will require more labour than a cafeteria-style operation or a fast-food restaurant. Also, a restaurant that requires a higher level of skill to prepare complex dishes will require more experienced staff, which in turn means higher wages.
Quantity of Meals and Number of Meal Periods
The volume of business will affect the amount of labour required. Each restaurant will have a minimum staffing level without which it cannot operate. If it serves fewer people than this minimum staffing level can handle, the labour costs will be very high.
The number of meal periods can affect the productivity of the restaurant if different menus for each period require set-up and tear-down time. As well, different menus will usually mean a larger number of menu items, also affecting labour.
Facility Layout and Design and Production Equipment
Restaurant kitchens are often designed last, after all of the seating area has been designed. As a result, the space may be awkward and inefficiently laid out. To work efficiently, all work surfaces and storage areas required to produce an item should be located close together, as shown in Figure 27. This includes dry storage, refrigerated storage, freezers, storage for plates and glassware, work counters, grills, fryers, and ovens.
Poor kitchen layout can limit the number of individuals who can work efficiently. It may require time-consuming trips to distant storage areas to obtain food items or dishes. If the layout of the kitchen is too spread out, the minimum staff needed to operate each station may increase. For example, if a salad preparation station is located away from the main kitchen, you may require a salad preparation person even when the restaurant is not busy.
Production equipment such as mechanical peelers, choppers, and mixers can reduce the amount of time spent doing these tasks. The key in selecting the appropriate facility design and equipment is to match these parameters to expected volume of business. For example, if you purchase too large a mixer for the volume of business, the work involved in cleaning the machine after use will not warrant the extra expense of purchasing the equipment. On the other hand, too small a mixer will reduce efficiency as you will be unable to mix the quantities needed in a single batch.
Similarly, if your kitchen layout is very compact, you may be able to run efficiently with only one cook. However, you may be unable to meet the demands of a high volume of sales because the kitchen is too small to accommodate more than a couple of staff.
Work Environment and Number of Hours Worked
A hot, humid, noisy environment reduces comfort and increases stress and may negatively affect performance. Long hours and hard work without reasonable breaks can lead to reduced productivity. The same is true if you are understaffed. Not having enough staff means that everyone else has to work harder or for longer hours, resulting in tired staff and reduced productivity.
Productivity Standards
A first step in determining staffing needs is to establish productivity standards. These standards must take into account the amount of time necessary to produce food of the required quality. The standards are based on procedures dictated by standard recipes.
Productivity standards are measured in labour dollars or labour hours. Labour dollars measure productivity in terms of the number of dollars that must be paid out in labour to generate a certain revenue. The advantage of this approach is that budgets and financial statements are also expressed in dollars so comparisons can be easily made. However, it can be very time-consuming to calculate the labour dollars given different wage and salary scales. Labour hours must still be calculated because the number of hours determines wages.
Labour hours indicate the number of hours of labour needed to produce a given number of meals or generate a certain amount of sales income. When you use labour hours as a standard, it is less time-consuming to calculate. As well, some simple tasks may take the same amount of time to complete, whether they are performed by a chef or a dishwasher.
Determining Requirements
The productivity standard is determined by comparing number of labour hours scheduled to meals served or to sales income generated. It can be produced by department, by shift, by position, or by position and shift. More detailed standards make it easier to pinpoint problem areas and take corrective action. The most detailed is to prepare productivity standards by position and shift. This allows you to examine the efficiency of each staff member.
It makes sense to look at each position and shift. For example, a breakfast cook working with a limited breakfast menu and items that are easy to prepare can produce many more meals in a hour than the cook on your evening shift who has a large number of menu items with more elaborate preparation needed. Generally, more servers are needed than cooks for a given number of meals. Fewer dishwashers may be required. If only a single labour standard is developed for the restaurant, it will be harder to pinpoint problems with labour costs.
Staffing Guide
A staffing guide tells the manager how many labour hours are needed for each position and shift to produce and serve a given number of meals in the given restaurant. It incorporates the productivity standards. It tells managers what number of labour hours are needed for the volume of business forecast for a given meal period. The labour hours can be converted into labour dollars to establish standard labour costs.
The staffing guide serves as a tool for planning work schedules and controlling labour costs. The labour hours in the guide can be converted into labour dollar and standard labour costs by multiplying the labour hours for each position by the wage scale for that position. The staffing guide should be based on the performance of good employees. When scheduling new employees who have not completed an orientation training period, allowances will have to be made for their lower productivity.
This form of staffing guide is much more useful than industry guidelines that do not take into account the specific factors which affect the productivity in your workplace. It may still be useful to compare your staffing guide to other properties in order to assess how competitive you are.
An example of a staffing guide is shown Figure 28. Note that the staffing guide shows the minimum number of staff per peak service period.
Figure 28: Staffing Guide
Figure 28: Staffing guide
Type of Restaurant Servers Bus Persons Chef or Sous Chef Cooks Dishwashers Hosts
Coffee shop 1 per 25 seats 1 per 5 servers 1 per shift 2 per 65 meals 1 per 100 meals 1 per 10 servers
Casual dining room 1 per 20 seats 1 per 4 servers 1 per shift 2 per 50 meals 1 per 65 meals 1 per 8 servers
Formal dining room 1 per 15 seats 1 per 2 servers 1 per shift 2 per 40 meals 1 per 65 meals 1 per 4 servers
Fixed Labour Costs
One factor that must be considered before developing a staffing guide is fixed costs. Fixed costs refer to the costs of running the operation that do not vary depending on the volume of business. For many businesses, the cost of the building, heating, lighting, insurance, and other similar costs are fixed. They do not change if the restaurant is busy or half empty. In fact, they continue even when the restaurant is closed.
Some labour costs are also fixed. If a restaurant has salaried employees, these costs are fixed and do not change depending on the volume of business. The business must pay the salary of these employees, even if the restaurant is not busy. In most restaurants, management positions, including the chef and sous-chefs, are salaried employees.
Variable Labour Costs
Variable costs must also be accounted for. Variable costs are costs that change based on the volume of the business. Food costs are the most obvious example of variable costs. Provided that the restaurant has not overstocked food, food costs will increase in a direct correlation with the volume of business. Labour hours above the salaried staffing levels are also variable costs. As the volume of business increases, hourly labour costs will increase proportionately.
Peak Periods
When the staffing guide is used to develop a staff schedule, the supervisor needs to consider the peak periods. For example, if the volume reaches 150 meals, 10.5 labour hours may be needed in the kitchen. An analysis of sales shows that the busiest period is between 6 p.m. and 9 p.m. The supervisor might schedule the cooks so that the first cook comes in from 4:00 p.m. to 9:30 p.m. and the second cook comes in from 6:00 p.m. to 11:00 p.m. This would ensure that there are two cooks available to prepare meals throughout the busiest period.
Scheduling Staff
The scheduling of staff is based on the labour hours needed to meet the projected sales volume. The supervisor also needs to keep an eye on labour dollars by considering whether staff on a lower wage scale could be scheduled. For example, on holidays or other times when overtime rates must be paid, it would be less costly to bring in a new employee who is not eligible for statutory holiday pay. Other factors to consider when developing schedules include the following:
• Staggered work schedules can be used to meet the demand over peak periods without incurring additional labour costs throughout the full shift.
• Part-time staff can be used to work short shifts of four or five hours to reduce overall labour costs.
• Full-time staff are usually used to cover all key administrative positions; sometimes full-time positions can consist of a mix of supervisory and front-line tasks in order to make up a full-time job.
• Temporary employees can be used to meet labour needs that are temporary in nature such as banquets, employee illness, or vacation relief.
• Legal considerations such as the requirements of the Employment Standards Act and provisions of the collective agreement must be kept in mind.
• Staff capabilities should be taken into consideration; some employees may thrive in a stressful dinner rush while others perform well under less stressful situations. Some employees may have additional skills (e.g., hosting, bartending), which can be used effectively when sales volume is low if collective agreements or staff policies permit.
• Employee’s preferences should also be accounted for in the schedule. Policies should be in place for requesting shift preferences or exchanging shifts between staff members.
No matter how well you have planned the schedule, problems can arise. A staff member may call in sick or fail to show up without warning. The volume of sales may be lower or higher than anticipated. You must have contingency plans to deal with these problems. You could have a staff member (or a casual employee) on call in case he or she is needed. You also have to know the capabilities of your staff. On a night when you have mostly experienced, capable servers and cooks who can handle stressful situations, you may be able to get by with one fewer staff than your staffing guide calls for.
When demand is lower than expected, you must know what limitations there are on sending staff home early, while still maintaining the minimum staffing needed to remain open. Of course, you must comply with collective agreements and all legislation that affects your workplace. If you understand the agreements and the Employment Standards Act well, you will know what flexibility you have to adjust to the situations that arise in the workplace.
Staying within Budgeted Labour Cost
A comparison of actual to budgeted labour costs can be used to plan future expenses. If your labour costs are higher than desired, you need to find ways to reduce them. One method of analyzing the labour costs is to look at the actual and budgeted labour cost percentage. The projected labour cost percentage is calculated by dividing labour dollars by the projected volume of sales. The actual labour cost percentage is the actual labour dollars spent for a given time period divided by the actual volume of sales.
Example 36
A small restaurant has the standard labour hours and rates of pay shown in Figure 29.
Figure 29: Labour planning and cost sheet
Position Labour Hours for 50 Meals Labour Hours for 75 Meals Labour Hours for 100 Meals Hourly Rate (inc. benefits)
Food server 8.5 12.5 16 \$9.85
Bus person 6.5 6.5 9 \$10.95
Cook 7 10 14 \$16.50
Steward 6.5 6.5 9 \$12.00
Host 0 0 4 \$10.25
Based on previous sales figures for a Tuesday night, the manager expected 77 customers on a particular Tuesday evening. The projected revenue for this evening was \$1500.25. The manager developed a staff schedule based on the labour hours for 75 meals. The labour dollars were computed by multiplying the scheduled hours for each position by the hourly rate. The total labour cost for the evening was \$437.30. The projected labour cost percentage was:
\$437.30 ÷ \$1500.25 × 100 = 29.1%
On this evening, the sales were down. Although 76 customers were served, very close to the number expected, the average cheque size was lower. Only \$1425.95 worth of menu items was sold. The actual labour cost percentage was:
\$437.30 ÷ \$1425.95 × 100 = 30.7%
One of the best ways to improve productivity is to continually review and revise performance standards. Use the problem-solving process to identify the problem, generate alternatives, evaluate the alternatives, choose the best ideas, and implement them. Some questions you might ask yourself are:
• Can a particular task be eliminated?
• Is training needed to improve the skills of staff?
• Can a task be reassigned to a person who is not as busy (e.g., could the dishwasher assist with some pre-preparation of items early in the shift)?
• Can slow periods be utilized more effectively to prepare for high-volume times?
• Does the menu need to be simplified?
• Do menu or volume changes require changes in facility layout?
• Would convenience items reduce costs without reducing the required quality?
• Are the activities of another part of the operation affecting the performance of this department (e.g., the catering department has opened a new conference room some distance from the kitchen which requires food service)?
• Have there been changes in volume and peak times that need to be considered?
After considering all of these factors, you may still not be able to reduce your labour costs. You may have to raise your menu prices to improve the profitability of your operation. Of course, you need to consider the price the market will bear and the prices charged by your competitors before taking such an action.
It is often useful to look at both your food costs and labour costs when deciding whether a price increase is needed. If your labour costs are a little higher than anticipated and your food costs are lower, there may not be a problem. Some companies use a figure of 70% to 80% as a target for the sum of labour and food costs. Another strategy is to have lower contribution margins, but increase your volume. This makes sense because the more volume you have, the more money is contributed toward meeting your fixed costs of doing business.
Position Performance Analysis
Productivity standards are developed by considering the labour hours needed to perform assigned tasks. During a designated observation period, employees are asked to perform their jobs, adhering carefully to all established policies and procedures. They are carefully observed to ensure compliance. For example, cooks would be expected to follow all standard recipes, take scheduled rest breaks, and meet the required quality standards. This process of analyzing productivity is called a position performance analysis.
The employee is observed over several shifts. At the end of each shift, the supervisor completes a report, as shown in Figure 30, which indicates the name of the employee observed, the meal period considered, the number of meals prepared, number of hours worked, and number of guests per labour hour. The supervisor also records comments on workflow, adequacy of service, problems that arose, etc.
Figure 30: Position performance analysis
Position:
Name of employee:
Shift
Date April 5 April 6 April 7 April 8
Number of meals served
Number of hours worked
Number of meals per labour hour
Supervisor comments
General comments
Recommended meals per labour hour for this position: 30
Performance review by: Restaurant manager
Tools like this can help you identify the productivity of each staff member. Perhaps one cook is capable of producing 40 meals to the same standard in the time it takes another cook to produce 30. The first cook is more productive, and therefore a better choice to schedule on the busier evenings. You may also use this analysis to set goals and identify development options.
All in all, food costs and labour costs make up the bulk of the costs in running a successful kitchen. Having a solid understanding of both and how to manage them will be key in running a successful food service operation, whether it be a food truck or a major hotel. | textbooks/workforce/Food_Production_Service_and_Culinary_Arts/Basic_Kitchen_and_Food_Service_Management_(BC_Campus)/04%3A_Labour_Costing/4.01%3A_Productivity.txt |
Learning Objectives
• Describe the basic calculation of operating costs
• Describe budgets and profit/loss statements
• Interpret point-of-sale information
05: Budget and Business Planning
In order to make a profit and stay in business, a food service operator must be aware of costs. The biggest cost in most operations is the raw ingredients used in the preparation of menu items.
Labour costs are also a significant part of a restaurant’s operating costs. You must schedule enough staff to meet the labour demands of the food service operation without incurring unnecessary costs. Point-of-sale (POS) reports provide information that is useful in analyzing both food and labour costs. They can also help you review your menu to make it more profitable.
A basic understanding of accounting is a useful skill in the food service industry. In fact, budgeting and interpreting profit and loss statements are essential management skills.
5.02: The Basic Calculation of Operating Costs
Fixed Costs
A fixed cost does not vary in relation to sales. A typical fixed cost is rent. In most cases, the cost of rent does not vary from month to month in response to how many meals you serve. Rent tends to be a constant cost for the length of the lease agreement signed by the restaurant and the landlord of the building. Property taxes, insurance premiums, and equipment depreciation are all fixed costs.
Some labour costs are often considered to be fixed. Those staff who are paid regardless of the amount of business being generated have a predictable cost that remains constant during the life of the contract or understanding you have with the employees. Such staff often includes full-time cashiers, managers, the head chef, and bookkeeper. Janitorial services are considered a fixed cost. The cost of staff who are hired as a result of an increase in business, technically, should not be considered a fixed cost.
To a certain extent, basic energy costs such as heat and light are fixed in that it is possible to determine a minimum level of need for energy regardless of the number of sales. Costs above the minimum level should reflect an increase in business and so often are not considered fixed, but in these examples, energy costs will be considered fixed costs.
Fixed costs themselves can be categorized as controllable and non-controllable.
A controllable cost is one that can be changed in the short term. For example, even though janitorial cost has been budgeted as a constant cost, it may be possible (if there is no ironclad contract with a janitorial service) to reduce the service and the cost on short notice. Advertising and promotion are also controllable fixed costs as a decision to change the amount of money spent can be made very quickly.
Non-controllable fixed costs are those costs that cannot be changed quickly by management. The most common non-controllable fixed cost is rent or lease payments and depreciation.
In most basic calculations, the only truly fixed costs are overhead costs, those ongoing expenses required to operate the business that are not direct costs of producing the food or presenting the service.
Variable Costs
Variable costs are directly related to sales. For example, the use of napkins or linen often varies due to an increase or decrease in sales. Other variable costs include food, beverages, and some labour costs. Usually, the major variable cost is food and most of the labour.
Variable costs are controllable. Less expensive ingredients can be purchased, portion sizes can be changed, and some workers can have their hours reduced usually on short notice.
In most basic calculations, the only variable cost used is food cost.
Semi-variable Costs
Labour costs are sometimes categorized as semi-variable because some are fixed but many are variable. In most situations labour cost is fully controllable. That is, you are in control of how many people work how many hours per day through proper scheduling. For basic calculations, labour is often given a category all on its own. In this context, labour costs will be considered semi-variable.
Breakeven Point
The only way costs can be recovered is through sales. When the sales income equals the cost for labour, overhead, and food, the breakeven point has been reached. That is, the breakeven point occurs when
sales = labour + overhead + food costs
Example 37
Labour for a week is \$3000, overhead is \$2000, and food cost is \$4000. Therefore, the breakeven point for sales occurs at \$9000, which means in order to stay in business, this operation must have sales of at least \$9000 each week. Any amount above \$9000 is profit,
The profit is determined by subtracting the total costs from the sales. That is,
profit = sales − (labour + overhead + food costs)
Cost Percentages
The breakeven point determined above is in raw dollar figures. Of more importance in the industry are cost percentages in general and food cost percentage in particular. In a well-run operation, cost percentages will remain relatively constant even though the dollar figures can vary widely week to week or month to month. However, if volume increases, so will efficiency which will, in turn, lower the production costs and increase the profits.
A cost percentage is derived by dividing a cost by the sales and expressing the answer as a percentage. That is, in general,
cost percentage = cost ÷ total sales
and, in particular,
food cost percentage = cost of food ÷ total sales
labour cost percentage = cost of labour ÷ total sales
overhead cost percentage = cost of overhead ÷ total sales
To illustrate the use of these formulas, consider the example below.
Example 38
A restaurant has total sales of \$2500. The food cost was \$1000, labour cost was \$850, and overhead was \$650.
Determine the cost percentages. Remember that percentages are always expressed as a portion of 100, and therefore the decimal figure resulting from the cost divided by total sales should be multiplied by 100.
food cost percentage = cost of food ÷ total sales
= \$1000 ÷ \$2500
= 0.4
= 40% (0.4 × 100)
labour cost percentage = cost of labour ÷ total sales
= \$850 ÷ \$2500
= 0.34
= 34% (0.34 × 100)
overhead cost percentage = cost of overhead ÷ total sales
= \$650 ÷ \$2500
= 0.26
= 26% (0.26 × 100)
In this example, the sales figure used is actually the breakeven point. In most instances, the total sales will be more than the breakeven point and the excess represents the before-tax profits of the business.
Example 39
A restaurant has sales of \$3500, food costs of \$1250, labour costs of \$800, and overhead costs of \$700. Determine the cost and profit percentages.
food cost percentage = \$1250 ÷ \$3500
= 0.357
= 35.7%
labour cost percentage = \$800 ÷ \$3500
= 0.2285
= 22.9%
overhead cost percentage = \$700 ÷ \$3500
= 0.2
= 20%
profit in dollars = total sales – (food cost + labour cost + overhead cost)
= \$3500 – (\$1250 + \$800 + \$700)
= \$3500 – (\$2750)
= \$750
profit percentage based on total sales = \$750 ÷ \$3500
= 0.214
= 21.4%
The before-tax profit percentage is over 20% in this example. Most restaurant operations probably do not reach this high a profit figure.
Another way to determine the percentage profit is to add the cost percentages and subtract the answer from 100%. Using the example above,
profit percentage = 100% – cost percentages
= 100% – (35.7% + 22.9% + 20%)
= 100% – 78.6%
= 21.4%
Note: All of the prices/costs used are examples and not intended to reflect the current costs of ingredients, labour, or menu items.
Interpreting Cost Percentages
Cost percentages are useful because they allow you to compare the performance of an operation at separate times during the year or to compare two similar restaurants. They also allow you to make generalizations about types of restaurant operations. For example, fast-food restaurants often rely on convenience foods that are expensive to purchase. In these restaurants, food percentage costs can be slightly higher, but the labour cost tends to be lower than in full-service restaurants. The profit is derived by having a high turnover of products and keeping labour costs low.
Fine-dining, high-margin restaurants tend to rely less on convenience foods and more on quality ingredients and a high level of service. Although food costs in raw dollars are high for such restaurants, the food cost percentage may be lower than in fast-food restaurants because menu prices are much higher. Labour cost percentages also tend to be higher because higher trained personnel is needed. The profit in these operations often is derived from serving relatively few customers but collecting more dollars per sale compared to more casual places that operate based on high volume.
Using Cost Percentages
The basic equation for cost percentages can be written several ways:
cost % = cost ÷ total sales
sales = cost ÷ cost %
cost = total sales × cost %
These formulas are useful when restaurant management decides on a cost percentage value and then has to see what that percentage means in terms of menu prices.
Example 40
Management has decided that a minimum food percentage of 30% must apply to all menu items. You wish to introduce an item that costs \$4.50 in actual food costs. To find the menu price (selling price) you would do the following:
selling price = cost ÷ cost %
= \$4.50 ÷ 30%
= \$4.50 ÷ 0.3
= \$15.00
Example 41
A group of people wish to have a Christmas banquet meal at a cost to them of no more than \$18.50 per person excluding tax and gratuity. If the food percentage is 30%, you can determine the actual food cost by doing the following:
cost = selling price × cost %
= \$18.50 × 30%
= \$18.50 × 0.30
= \$5.55
The cost figure is used to determine the banquet items that could be produced by the restaurant using no more than \$5.55 in raw materials per serving.
For additional information on cost percentages and establishing menu prices, refer to the chapter on food costing.
Sales Ratios and Other Statistics
Very often, restaurant managers generate statistics to determine the efficiency of their operation. Some of these statistics are based on dollar sales while others are based on non-monetary items such as the number of customers in the restaurant during a busy or slow time period. These statistics are used to determine trends in sales, identify menu items that are not moving, calculate staffing requirements, and so forth.
The statistical data tends to be quite straightforward. For example, total dollar sales is simply the amount of money that has gone through the cash register over a designated period of time (a day, a week, a month, or a year). Sometimes the total dollar sales figure is divided by the number of customers served to produce an average dollar sale (average cover). The average dollar sale is useful if the impact of a new menu or a special sales promotion has to be evaluated.
Sales per server and average sales per server are often used to determine the effectiveness of individual waiters and waitresses. The statistics are compiled by either just noting the total number of sales of each server over a period of time (sales per server) or by dividing the total number of sales by the number of servers (producing the average sales per server). In many restaurant operations, these statistics are automatically produced by a point-of-sales terminal.
Some chain restaurant managers compute a sales-per-seat statistic by dividing the total sales by the number of seats in their restaurant. The statistic is useful in comparing the activity among members of a chain of restaurants.
Rational menu changes can be made only after data has been collected that can be used to analyze the popularity of the dishes offered. In older operations, current statistics are often compared to historical statistics so trends can be predicted. The most common menu statistic is simply the number of times each item on the menu is ordered over a given period.
Closely related to the number of times a menu item is ordered is the sales mix of the restaurant. Sales mix is determined by comparing the relative popularity of, for example, all entrées by expressing the number sold of each entrée as a percentage of all the entrées sold.
Example 42
Over a one-month period a total of 1200 entrées are sold of which 450 are steak sandwiches, 300 are fish and chips, 350 are hot roast beef sandwiches, and 100 are grilled cheese sandwiches. The sales mix percentages are:
sale percentage = entrée types sold ÷ total entrées sold
steak sandwich percentage = 450 ÷ 1200
= 0.375
= 38%
fish and chips percentage = 300 ÷ 1200
= 0.25
= 25%
roast beef sandwich percentage = 350 ÷ 1200
= 0.29
= 29%
grilled cheese sandwiches = 100 ÷ 1200
= 0.083
= 8%
The sales mix is about 38% steak sandwiches, 25% fish and chips, 29% hot roast beef sandwiches, and 8% grilled cheese sandwiches.
Seat turnover might be used to determine staffing. This statistic is simply the number of customers in a restaurant over a period of time (usually a busy period or a slow period) divided by the number of seats in the restaurant. For example, if a 50-seat restaurant serves 165 meals at lunch time, the seat turnover is 3.3, which means that the average seat was used over three times during that period. This can be valuable information for staffing arrangements.
Almost all of the statistics in the restaurant trade are now automatically collected by computers built into electronic cash registers or ordering equipment. Small operations may have to collect this data by observation. | textbooks/workforce/Food_Production_Service_and_Culinary_Arts/Basic_Kitchen_and_Food_Service_Management_(BC_Campus)/05%3A_Budget_and_Business_Planning/5.01%3A_Goals.txt |
An operating budget is management’s plan for generating revenue and incurring expenses over the time of the budget. Operating budgets are usually in effect for a fiscal year, but they are subject to alterations if anticipated revenues or costs change markedly from what was projected.
In the following section, it is assumed that there are records from previous years that can be used to create an operating budget. When a business first starts up, the operating budget is based upon a careful analysis of the market and the expertise senior management brings with them to the new enterprise from other jobs in the food service industry. Creating a first budget is beyond the intent of this book.
A budget is developed by calculating projected sales, determining required profit levels and fixed expenses, and calculating food costs.
Example 43: Sales/Cost/Profit Equation
Profit can only occur when sales exceed the break-even point. That is,
profit = sales − costs
= sales − (labour + food costs + overhead)
or sales = labour + food costs + overhead + profit
Overhead is a fixed cost. Your rent payment usually is the same regardless of the level of your sales. Labour costs are semi-variable costs. As was explained earlier, some labour costs are constant and must be paid even if sales do not meet expectations while other labour costs are the result of increases in sales.
Since labour costs are not truly fixed, the variable part of the cost of labour can be manipulated in times of poor sales by cutting back on paid hours, introducing shift changes, and even laying off personnel. Personnel working in the food industry often learn how flexible their hours can become in times of poor sales!
Hoped-for profit can be treated as a fixed cost. Often, profit is considered to be that which is left over after all costs have been paid. However, more and more businesses try to treat profit as an expense that should be met.
With the exception of some labour costs, only the cost of food is truly a variable cost in the cost/profit equation because the amount of food purchased is directly influenced by the amount of food sold by the establishment.
By determining overhead, labour, and profit costs, you can calculate optimum food costs by subtracting all the other costs from projected total sales. This relationship can be seen by manipulating the sales equation presented above (sales = labour + food costs + overhead + profit) into food costs = sales – (labour + overhead + profit).
Planning for a Profit
The first step in planning for a profit is to determine how much return the investor or company needs. The restaurant business is considered a risky investment. Some people make a lot of money; more people go broke. If people can earn 10% by investing their money in safer investments, investors will expect to earn more than this as they have a chance of losing all their money.
Example 44
A restaurant owner has put up \$100 000. The owner wishes to have a profit of 15%. The cost to the restaurant for the use of this money is:
cost (profit) = principle × interest rate
= \$100 000 × 15%
= \$100 000 × 0.15
= \$15 000
Calculating Other Costs
Remember, fixed costs include rent, heat, light, and other overhead costs. For this discussion, assume the restaurant has been in business for a number of years and last year the overhead costs amounted to \$55 000. These costs have been increasing at about 5% per year.
Example 45: Projected Food Cost
The projected fixed cost for next year will be:
new overhead cost = old overhead cost + increase in overhead cost
= \$55 000 + (5% of old cost)
= \$55 000 + (0.05 × \$55 000)
= \$55 000 + (\$2750)
= \$57 750
The semi-variable cost of labour can be treated in much the same manner. Assume that last year labour costs were \$75 000 which was an increase of 5% over the previous year. Other indicators suggest that labour costs will increase about the same for the coming year.
Example 46: Projected labour cost
The projected labour cost for next year will be:
new labour cost = old labour cost + increase in labour cost
= \$75 000 + (5% of old cost)
= \$75 000 + (0.05 × \$75 000)
= \$75 000 + (\$3750)
= \$78 750
Calculating Projected Sales Levels
To forecast sales it helps to have a past record on which to base projections. Assume such records are available and the last year sales were at \$225 000. It is thought sales can be increased by 10% this year.
Example 47: Projected sales
new sales level = old sales level + increase in sales level
= \$225 000 + (0.10 × \$225 000)
= \$225 000 + \$22 500
= \$247 500
Calculating Food Costs
To calculate food costs, use the equation derived previously.
Example 48: Food costs
food costs = sales − (labour + overhead + profit)
In the example being developed, food costs are:
food costs = sales − (labour + overhead + profit)
= \$247 500 − \$78 750 − \$57 750 − \$15 000
= \$96 000
If all the expenses are to be met, the restaurant should not spend more than \$96 000 in food costs. From this amount, the restaurant must generate \$247 500 in sales.
Cost Percentages
Once all the costs have been determined (predicted), it is fairly easy to determine cost percentages. In the example under discussion, the cost percentage can be determined using the basic cost percentage equation below.
Example 49
cost % = cost ÷ sales
labour cost % = labour cost ÷ sales
= \$78 750 ÷ \$247 500
= 0.318
= 31.8%
overhead cost % = overhead cost ÷ sales
= \$57 750 ÷ \$247 500
= 0.233
= 23.3%
profit % = profit ÷ sales
= \$15 000 ÷ \$247 500
= 0.0606
= 6.1%
food cost % = food cost ÷ sales
= \$96 000 ÷ \$247 500
= 0.3878
= 38.8%
The information gathered above can be used to generate a projected budget.
Calculating Projected Sales
Past sales figures are collected from monthly up-to-date income statements and from the audited budget of the previous year. The past sales should be carefully analyzed to see if any trends are emerging. For example, if sales have been falling in the last quarter, you want to ask why, as the drop in revenue may be a sign of continuing trouble in the new fiscal year.
The assumption is usually made that growth in the past year will mean growth into the new year. This is probably true but only if the conditions of the new year are thought to be nearly the same as the past year. If a new restaurant is going in across the street, if the local mill is going to lay off 150 workers, if previously untaxed food is going to be subjected to a sales tax, or if the minimum wage is going to be increased and you depend on help paid at or near that level, past growth records may mean very little. Equally important are positive changes in the community. For example, an excellent review from a restaurant critic can have a huge impact on business that was not counted in your projections.
If possible, compare the monthly food sales of last year with its corresponding sales for the previous year. Again, this is only possible if the restaurant has been in business a few years. Such a comparison is shown in Figure 31.
Figure 31: Sales comparison year over year
Sales comparison year over year
Month Sales This Year Sales Last Year Difference Percentage Change
January \$20 925 \$19 020 \$1 905 10%
February \$21 390 \$19 810 \$1 580 8%
March \$22 090 \$19 725 \$2 365 12%
April \$23 020 \$21 320 \$1 700 8%
May \$23 030 \$21 730 \$1 300 6%
June \$23 950 \$21 780 \$2 170 10%
July \$23 715 \$21 365 \$2 350 11%
August \$23 720 \$21 200 \$2 520 12%
September \$23 320 \$20 710 \$1 610 8%
October \$25 110 \$22 900 \$2 210 10%
November \$24 830 \$22 200 \$2 630 12%
December \$24 900 \$21 240 \$3 660 17%
Totals \$279 000 \$253 000 \$26 000 10%
The sales picture looks bright in Figure 31. Management could probably safely assume that next year the growth will continue. They would then draw up an estimated monthly sales chart.
The monthly projections can be used in the next fiscal year to track sales in relation to the projection. For example, if sales in January are significantly less than the projection, is it time to worry, or can the loss be picked up next month? That is the type of question management has to be constantly asking.
A monthly projection is shown in Figure 32. Last year’s sales are increased by 10%, which is the total percentage change in sales as reflected in Figure 31. Less conservative managers might be tempted to project a greater percentage increase based on the steady growth since June. However, it is usually best to err on the side of caution as it tends to be easier to handle excess income than it is to handle income shortfalls. But, if sales do increase dramatically, management should be prepared to redraw the budget.
Figure 32: Sales projections based on previous year’s growth
Sales projections based on previous year’s growth
Month Sales This Year Increase by 10% Projected Sales
January \$20 925 \$2 090 \$23 015
February \$21 390 \$2 140 \$23 530
March \$22 090 \$2 210 \$24 300
April \$23 020 \$2 300 \$25 320
May \$23 030 \$2 300 \$25 350
June \$23 950 \$2 400 \$26 350
July \$23 715 \$2 370 \$26 085
August \$23 720 \$2 370 \$26 090
September \$22 320 \$2 230 \$24 550
October \$25 110 \$2 510 \$27 620
November \$24 830 \$2 490 \$27 320
December \$24 900 \$2 500 \$27 400
Totals \$279 000 \$27 910 \$306 910
Determining Profit Levels and Costs
Again, the best plan is to analyze past costs and see if they can be lowered and to determine if the profit level must be adjusted. Costs tend to go up, but fixed costs may stay at the same level as in the previous year while some controllable costs might actually decline after careful analysis.
Costs include the following:
• Food costs, sometimes called product costs
• Controllable expenses, such as labour, advertising, janitorial service, promotion, utilities, maintenance
• Uncontrollable costs, such as rent or lease payments, licence fees and property taxes, sometimes referred to as occupancy costs
• Depreciation, which is uncontrollable but not an occupancy cost
If the figures are available, monthly costs of the current and last operating years can be used. However, it is quite acceptable to use the annual current cost and prorate across every month by using cost percentage figures on the projected sales for each month.
To find annual cost figures, monthly reports can be used and summarized on a single form (Figure 33). Alternatively, the previous year’s income statement can be used.
Figure 33: Annual cost figures
Figure 33. Annual cost figures
Food cost \$110 000
Payrolls costs \$75 000
Other controllable costs \$35 000
Occupancy costs \$25 000
Depreciation \$12 000
Profit (before taxes) \$22 000
Total \$279 000
To convert the figures into cost percentages, the individual costs are divided by the total sales (Figure 34). The percentages have been rounded off to the nearest percent.
Figure 34: Annual cost percentages
Figure 34. Annual cost percentages
Item Cost Cost Percentage
Food cost \$110 000 39%
Payroll costs \$75 000 27%
Other controllable costs \$35 000 13%
Occupancy costs \$25 000 9%
Depreciation \$12 000 4%
Profit (before taxes) \$22 000 8%
Total \$279 000 100%
If management feels that before-tax profits have to be increased by more than the amount that will be generated by multiplying the present profit percentage by the projected sales, decisions will have to be made regarding increasing sales or reducing costs.
Creating the Projection Budget
For simplicity, costs have not been broken down into the subcategories as they would appear on an actual budget statement. However, the example shown in Figure 35 provides a general idea of what a monthly budget looks like.
Figure 35: January sample budget
Figure 35. January sample budget
A B C D E F G H
Item Budget % Month (Budget) Year (Actual) Month (Actual) Year Variance Actual %
Food sales \$23,015.00 \$306,910.00 \$23,100.00 \$23,100.00 \$85.00
Food cost 39.0% \$8,976.00 \$119,695.00 \$9,110.00 \$9,110.00 \$(134.00) 39.4%
Payroll costs 27% \$6,214.00 \$82,866.00 \$6,205.00 \$6,205.00 \$9.00 26.9%
Other controllable costs 13.05 \$2,992.00 \$39,898.00 \$3,110.00 \$3,110.00 \$(118.00) 13.5%
Occupancy costs 9.0% \$2,071.00 \$27,622.00 \$1,955.00 \$1,955.00 \$116.00 8.5%
Depreciation 4.0% \$921.00 \$12,276.00 \$921.00 \$921.00 4.0%
Profits 8.0% \$1,841.00 \$24,553.00 \$1,799.00 \$1,799.00 \$(42.00) 7.8%
Total expenses \$23,015.00 \$306,910.00
Notice the food sales projection amounts (Columns C and D) are from Figure 32 and the cost percentages (Column B) are from Figure 34. The actual amounts (Column E and F) would be computed from the monthly sales report.
The monthly budget form should be completed soon after all expenses are known. Most business will have accounting software that will track the costs and actual sales against the budgets.
Interpreting a Budget
The simplest way to examine a budget is to go through it in point form line by line. The following refers to Figure 35.
• Food sales are \$85 greater than expected. The actual month figure in Column E would be from the monthly sales receipts. Since this budget form is for January, the yearly figures in Column F are the same as the figures in Column E. Next month, however, the figures in Column F would be determined by adding the figures for this month and the actual figures from the February sales receipts.
• Food costs are higher than projected and are even greater than the increase in food sales. Since sales are higher than projected, food costs should also be higher but the figure suggests that food costs should be watched carefully for the next few months to see if increases in wholesale prices are more than what has been budgeted for.
• Payroll costs are slightly lower than projected. The difference is very slight (as they are in all categories), so no staffing decisions can be made based on this first month’s report.
• Other controllable costs are a bit higher but insignificant. If an actual budget was being used, these costs would be broken down into several categories and the area causing the increase would be pinpointed.
• Occupancy costs are slightly lower than projected. This could mean that property taxes or a licence fee need not be paid until later in the year.
• Depreciation costs cover the expense of having to replace equipment that has worn out through age, wear, or deterioration. There are strict taxation rules for determining depreciation. In this example, depreciation remains constant during all the budget months.
• Profits are down from the projection because, in the example, profits have been determined as the difference between expenses and sales and so fluctuations and changes in sales and costs will be reflected in the profits for the month.
• The total expenses are the same as the projected and actual food sales for the month.
• The actual figures and the projected figures for the month are very close. This would suggest that, at least for this month, the budget process has been accurate. However, managers should look very closely at the areas where actual costs have exceeded estimates and pay particular attention to food costs.
Income Statement
An income statement is an official financial document that presents the actual income and expenses of a business for a declared period of time—often the end of each month and at the end of the fiscal year.
The income statement is essentially the monthly budget with actual cost and income figures inserted. For example, the income statement from the example above (Figure 35) could be laid out as shown in Figure 36.
Income statements are also known as profit and loss statements. An example of a detailed profit and loss statement is shown in Figure 37.
Figure 37: Detailed profit and loss statement
End of December, 20—
Sales
Customers \$ 258 310 (92.6%)
Staff meals \$ 12 500 (4.5%)
Returns and promotions \$ 8190 (2.9%)
Total sales \$ 279 000
Cost of sales
Beginning inventory \$ 16 500
Purchases \$ 105 900
Ending inventory \$ 12 400
Cost of food sold \$ 110 000 (39.4%)
Gross profit \$ 169 000 (60.6%)
Expenses
Payroll
Salaries and wages \$ 63 750 (22.8%)
E. I. and WorkSafe \$ 6000 (2.2%)
Casual labour \$ 5250 (1.9%)
Other controllable costs
Advertising \$ 9 800 (3.5 %)
Laundry and linen \$ 7700 (2.8% )
Cleaning and paper supplies \$ 10 500 (3.8%)
Freight and cartage \$ 5250 (1.9%)
Office supplies \$ 1750 (0.6%)
Occupancy costs
Insurance \$ 3000 (1.1%)
Utilities and fuel \$ 2750 (1.0%)
Repairs and maintenance \$ 500 (0.2%)
Lease \$ 18 750 (6.7%)
Depreciation \$ 12 000 (4.3%)
Total operating expenses \$ 147 000 (52.7%)
Total net profit \$ 22 000 (7.9%)
Note: The figures in brackets are cost percentage.
As you can see, there is a great deal of financial information that goes into the operation of a restaurant. Learning to understand and interpret the information is a skill that you will need to develop in order to manage a kitchen successfully.
Image Descriptions
Figure 36 image description:
Income statement for year ending December 31st.
Sales
• Food sales = \$279,00
• Total = \$279,000
Cost of sales
• Foot costs = \$110,000, 39%
Gross profit on sales = \$169,000, 61%
Controllable costs
• Payroll = \$75,000, 27%
• Other = \$35,000, 13%
• Total = 110,000, 40%
Profit after controllable costs = \$59,000, 21%
Occupancy costs = \$25,000, 9%
Profit before depreciation = \$34,000
Depretiation = \$12,000, 4%
Profit before income tax = \$22,000
[Return to Figure 36] | textbooks/workforce/Food_Production_Service_and_Culinary_Arts/Basic_Kitchen_and_Food_Service_Management_(BC_Campus)/05%3A_Budget_and_Business_Planning/5.03%3A_Operating_Budgets_and_Income_Statements.txt |
Point-of-sale information is information that is gathered from your daily (or even hourly) receipts. Before computerized equipment was available, a supervisor would analyze the sales at the end of each day using the handwritten guest cheques. The total number of customers, the average cheque size, and the amounts of each entrée sold were tallied and recorded. The supervisor would also compute total sales, check cash against cash register totals, and complete other financial records. The information from the sales analysis was used by the chef or restaurant manager to manage inventory, predict volume of sales, and judge the popularity of items.
Types of Point-of-Sale Equipment
Today, most point-of-sales reports are generated automatically by point-of-sales (POS) hardware and software. A simple POS system may be a single cash register connected to a computer terminal that stores data, or it may be more complex with multiple terminals, handheld devices or tablets, and even smartphones connected to the system by supported applications, and also connected to printers at various points in the system that will print orders directly in the kitchen or bar area.
POS systems consist of a number of terminals connected to a central processing unit (Figure 38). For a terminal to process transactions, it must be connected to the central unit which houses the software and memory to process the information. Several types of terminals may be available. A pre-check terminal is used to enter orders; it has no cash drawer. Many pre-check terminals are now available in hand-held cordless models, or tablets or smartphones can be used for this purpose.
In some systems, a pre-check terminal is used to enter and print the orders for a table. The printed copy is then given to the kitchen to relay the order. In other systems, the order is sent directly from the pre-check machine to a printer in the kitchen or bar. The server does not have to carry the order over to the pickup counter.
A separate cashier terminal is used to settle guests’ cheques. The information may also be sent automatically to a journal printer and a manager workstation. The journal printer is usually located in a secure area and provides management with a detailed systems audit.
POS systems produce very detailed receipts (Figure 39). The wealth of information recorded by the machine allows much more detailed analysis of sales than was possible when guest cheques were handwritten.
POS information is a powerful tool that permits you to analyze menu performance and revise menus, forecast labour requirements, forecast inventory requirements, and analyze staff performance and sales. POS systems have the ability to generate
• Sales analysis reports
• Labour reports such as employee hours, wages, credits for meals, numbers of guests served per server, gross sales per server, average cheque size per server, and so forth
• Inventory files that can be used by inventory management software to automatically deduct items from inventory based on the standard recipe for a menu item
• Other management reports such as a daily revenue report
Sales Analysis Report
A sales analysis report analyzes sales by menu item. It can be computed for any period of time including an hour, a meal period (e.g., breakfast, lunch), a day, a week, or a month. The detailed reporting permits you to identify peak periods precisely. Fast-food restaurants will often want to analyze sales hourly to maximize the utilization of labour. The report includes:
• Number of items sold in each period
• Individual and total food cost for each menu item during the period (based on standard recipes and standard costs)
• Total food cost for the period (also called expected cost or ideal cost)
• Ideal food cost percentage
Ideal Food Cost
The ideal food cost is based on actual items sold. It is calculated by multiplying the actual number of items sold by the standard food cost per item, then summing the costs for all menu items. The ideal food cost is then compared to actual food costs. The standard recipe and standard cost must be regularly updated and recalculated for the comparison to be valid. The two costs should be fairly close. Minor variations can be the result of special purchases of bulk items or the use of small quantities of some items that are not restocked on a weekly basis. Larger discrepancies may indicate waste due to spills and spoilage, pilferage, poor portion control, changes in quality and yield of stock (e.g., due to overcooking). Customer complaints can result in an item being discarded without being charged or a second item being cooked.
Example
You have noticed that your actual costs are higher than the ideal costs. You have been very careful about entering standard recipes and costs so you know that the comparison should be valid. You suspect poor portion control might be responsible. You could take a plate ready for service and scale all of the items on the plate. You might also check the weight of items that come portioned from the supplier. If your recipe specifies a 250 g (8 oz.) boneless chicken breast and the supplier is sending you chicken breasts that average 275 g, your food costs will be higher than expected.
Menu Analysis and Engineering
Sales analysis reports provide detailed information that can be very helpful in menu planning. The reports can analyze the profitability and popularity of each item. You can then use the results to review the menu and make changes. Refer to the section of this book on menu engineering for more detail on how to use this information.
Forecasting Inventory Requirements
POS information can also be used to forecast inventory and staff requirements. If you have sales records that indicate that in a typical week you sell 84 portions of salmon and 97 portions of sirloin steak, you can look at your current inventory and decide how much you need to order for the coming week. Figure 40 illustrates this scenario.
Figure 40. Forecasting Inventory Requirements
Menu Item Monday Tuesday Wednesday Thursday Friday Saturday Sunday Total % Mix
Italian pizza 7 9 10 10 25 22 17 100 11.90%
Cajun chicken 8 9 9 12 10 13 12 73 8.69%
Sirloin steak 5 8 6 8 27 25 18 97 11.55%
Chicken stir fry 10 7 9 6 10 15 11 68 8.10%
Prawn stir fry 5 5 6 11 8 8 6 49 5.83%
Linguine 9 9 9 16 8 11 12 74 8.81%
Linguine chicken 12 19 13 8 15 10 17 93 11.07%
Fettuccine alfredo 11 13 12 18 16 19 22 111 13.21%
Salmon 4 16 13 5 18 11 17 84 10.00%
BBQ chicken 15 11 10 11 9 19 16 91 10.83%
Total 81 106 97 106 146 153 147 840 100%
If you have detailed reports that indicate the sales mix over the week, you can predict the required quantities of stock more precisely. In this example (Figure 40), the sales shown for the entire week are broken down into daily totals. If you look at the sales for sirloin steak, you will notice that they are not evenly spread throughout the week. If you have a delivery on Friday that must last you until Monday, you must have at least 70 steaks on hand to last you through the weekend.
Forecasting Staffing Requirements
If you have detailed reports that indicate levels of sales by hour, meal period, and day, you will be able to identify peak days and times more easily. Figure 41 shows an example.
Figure 41: Volume of sales by hour and day
Meal Period Mon Tues Wed Thu Fri Sat Sun
5:00-6:00 56 72 48 54 53 119 123
6:00-7:00 94 156 117 119 94 121 131
7:00-8:00 145 183 156 173 156 163 165
8 :00-9:00 89 87 101 115 203 207 177
9:00-10:00 73 66 54 78 177 177 96
10:00-11:00 45 42 47 37 72 74 45
Total 502 606 523 576 755 861 737
You need to schedule staff for the restaurant. You need to know what times are busiest and how much staffing you will need for each period. In Figure 41, you can see that Monday and Wednesday are your slowest days, while Friday and Saturday are the busiest. There is also a different pattern for the peak times on weekdays versus the weekend. On Saturday and Sunday nights, volume peaks later in the evening and the peak period is much longer. For example, on Wednesday the peak of 156 guests comes between 7:00 p.m. and 8:00 p.m., while on Saturday, the peak is between 8:00 p.m. and 9:00 p.m.
Historical data collected from month to month and year to year is useful for projecting trends and seasonal variations in sales and, therefore, staffing needs. It may also be used to determine whether the sales figures you had for last Tuesday show an unexplained blip, or whether indeed Tuesday is usually a better day for your restaurant than Monday or Wednesday.
Another use for historical data is to project sales for holidays and special occasions. For example, last year, you had 250 guests for brunch on Mother’s Day. If this year, your average sales are up 10%, you might conclude that you need to have sufficient staff to handle 275 guests.
Manage Staff
POS information can also be used to manage staff. The software will allow you to prepare reports that track the sales of each server. You might be able to determine the average cheque size of guests served by each server. You could also track the amount of alcohol, appetizer, and dessert sales to see whether your servers are suggestively selling these items. If you have an incentive program to sell specific menu items or specials, you could track the staff member’s performance. These reports may be used to give feedback to staff on their performance and suggest methods of improving their sales.
Summary
Overall, the POS system has become a very effective tool for the industry to collect and manage a wide array of information. The advantages that the technology has brought are in the rapid calculation and analysis of a large amount of data, but all of these systems still require those who operate them and interpret the data to have a solid understanding of the principles of effective kitchen management and cost controls. | textbooks/workforce/Food_Production_Service_and_Culinary_Arts/Basic_Kitchen_and_Food_Service_Management_(BC_Campus)/05%3A_Budget_and_Business_Planning/5.04%3A_Interpreting_Point-of-Sale_Information.txt |
Thumbnail: Knife activity in the kitchen (Unsplash License; CA Creative via Unsplash)
01: Professionalism and Saute
Restaurants are an institution in nearly every country and culture in the world. The restaurant, which emerged during the French Revolution, continues to serve as a place where people come together to eat, drink, and socialize. However, even before Marie Antoinette and Louis XVI were sent to the guillotine, restaurants have been around in one form or another for thousands of years.
Ancient Restaurant, Wikipedia
Fruit Basket, Pompeii, C. AD 70, Wikipedia
The idea of selling food for profit existed during the earliest civilizations. It’s no coincide the growth of restaurants through history correlates with the growth of cities. The need for public eateries was firmly established as far back as the Roman Empire and Ancient China. When peasants and farmers brought their livestock and other goods to urban markets, often they traveled for several days at a time and needed a place to eat and rest. This brought about the earliest form of restaurants, the roadside inn.
Usually located in the middle of the countryside, inns served meals at a common table to travelers. There were no menus or even options from which to choose. Every night was chef’s choice.
Restaurants in the Middle Ages, Wikipedia
In Europe through the Middle Ages and into the Renaissance, taverns and inns continued to be the main place to buy a prepared meal. In Spain, these establishments were called bodegas, which served small savory Spanish dishes called "tapas." In England, food such as sausage and shepherd’s pie were popular; while, in France, stews and soups were offered. All of these early restaurants served simple fare commonly found in peasant or merchant homes.
Following Columbus’s voyage to the Americas in 1492, global trade increased, introducing new foods to Europe. Coffee, tea, and chocolate were soon being served in public houses alongside beer, ale, and wine. By the 17th century, while full meals were still typically eaten at home, moderately well-to-do people would hire a caterer or take their meals in a private salon, rather than in the main dining room of a public house.
France, Wikipedia Commons
In France throughout the Middle Ages, guilds had monopolies on many aspects of prepared food. For example, Charcutiers were the guild who prepared cooked meats for sale. If you did not belong to that particular guild, it was illegal to sell cooked meat in any form. In 1765, a man named Boulanger added cooked lamb to a stew he sold in his shop near the Louvre. The caterer’s guild sued him, but Boulanger won the case. Over the next 20 years leading up to the French Revolution, more shops like Boulanger’s began opening in Paris. Before Mr. Boulanger, guilds brought foods to the inns whose primary functions was to provide beds and drink.
Guilds of the Middle Ages
• Rotisseurs…………….roast spits
• Patissiers……………..poultry, pies, tarts
• Tamisiers……………..bread bakers
• Vinaigriers…………….soups & stews
• Traiteurs………………ragouts
• Porte-chapes…………feasts & celebrations
When Marie Antoinette and Louis XVI went to the guillotine, the old ways of French society went with them. The guilds were swept away and many chefs employed in aristocratic, even royal, households found themselves unemployed. Many of these displaced workers opened their own restaurants in Paris, bringing with them a new way of dining. Delicate china, cutlery, and linen tablecloths, all trappings of aristocracy, were now available to a completely new echelon of French citizens. Menus became more diverse, offering both prix fixe and a la carte options.
Though public houses continued to exist, the rise of fine dining in France would soon spread throughout Europe and into the New World.
Public gatherings over food and drink have long been a part of human society, as they offer a place for people to come together for a meal and to socialize with others. Following the French Revolution, fine dining restaurants expanded across Europe and to other parts of the world.
The Birth of Fine Dining
The term restaurant itself is French, once used to describe the rich bouillons served at taverns and public houses to restore the spirits and relieve ailments (restoratives). Following the French Revolution at the end of the 18th Century, unemployed chefs from aristocratic households began opening their own RESTAURANTS. They added touches of the upper class to their establishments. Guests did not have to take their meals at a common table, as was typical of taverns and roadside inns. Instead, they had private tables, held by reservations- a new concept. Antoine Beauvilliers of the Grande Taverne de Londre was the first to offer a menu, listing dishes during fixed hours served at individual tables.
They dined with fine china and cutlery, and tablecloths- all trademarks of modern day fine dining. Menus, either prix fixe or a la carte were framed and at the end of the meal, guests were presented with a check, tallying the amount of their bill.
Many fortunes were made by these professional chefs-turned-restaurateurs. They catered to a new class of provincial DEPUTES that came to Paris following the end of the Revolution. ‘Savvier restaurateurs’ adapted their eateries to include such amenities as bathrooms- for which there was a charge to use. Before the Revolution, there were less than 50 restaurants in Paris. By 1814, there were 3,000 restaurants listed in the Almanach Des Gourmands - a popular travel guide.
The French Help Define the Restaurant Concept
During the 19th Century, the number of restaurants in Paris continued to rise. After the defeat of Napoléon, wealthy Europeans flocked Paris to partake in the many gourmet-dining options. This was especially true of the allied officer ‘gentlemen’ - a move that would be repeated following the end of WWII. The 19th Century also marked the rise of Cafes, a style of restaurant that does not offer table service. Rather, customers order their food from a counter and serve themselves. Outside of Paris, soup kitchens and dairy shops offered home-style cooking for cheap, attracting members of the lower working class.
Gourmet Dining Goes Global
Mid 1800’s - Charles Ranhofer was the first “celebrity chef in the U.S. Delmonico’s was his restaurant, The Epicurean was his book. It was the Franco-American encyclopaedia of cooking. By the end of the 19th Century, advancement in transportation through steamers, railways and eventually automobiles brought about a change in travel. Luxury tourism grew and with it a new precedent of eating well away from home. No longer was eating while traveling a mere necessity. It became an art. Part of the travel experience was dining at famous Parisian cafes and restaurants, who by now had built a solid reputation for excellent food and service. The biggest contribution to today’s modern fine food establishments was made by the team of Escoffier and Ritz. In the 1820s, Cesar Ritz, a Swiss developer, partnered with a prominent French chef, Auguste Escoffier and built the Grand hotel of Monte Carlo, the first to offer luxury accommodations and gourmet dining all under one roof. Escoffier modernized the kitchen with his brigade system and streamlined the French Sauce System to five mother sauces. He is considered the father of 20th century French cuisine. Caesar Ritz was the service, décor and promotional genius.
Other luxury hotels soon began popping up all over Europe.
The 20th Century saw the French Restaurant go global. In Spain, it was a RESTAURANT. In Italy, it was called a RISTORANTE. In Great Britain and the United States, it remained RESTAURANT, but would soon evolve to fit the demands of changing consumers. By the end of that century, restaurants in the United States would evolve further, introducing the world to restaurant chains, the rise of modern-day fast food and an eventual return to the farm-to-table movement.
Evolution of Cooking Styles
Grande Cuisine – 17th and early 18th centuries. Very elaborate tables resplendent with dishes, architectural in their placement. Diners came and sat at the table and ate what they could reach.
By mid-1700’s, Antonin Careme refined the dishes and served them in dozens of courses. He studied classical architecture to better build works of confectionery.
Meanwhile, other chefs blended the cooking styles of Grande Cuisine with simpler dishes of the middles classes thus creating the new Cuisine Bourgeoise.
When Escoffier refined Careme’s ‘Grand Cuisine’ to the modern Cuisine Classique, he propelled French Cuisine into the twentieth century.
The style of cooking that emphasized the natural flavor of food became Nouvelle Cuisine in the 1950’s. Early masters were Fernand Point, Jean and Pierre Troisgros, Alain Chapel, Roger Verge and Paul Bocuse. Roux and cream sauces gave way to broths and reductions. Lighter and naturally flavored foods prevailed.
By mid-twentieth century in the U.S. fiery hot ethnic cuisines became popular; Szechuan, Hunan, Thai, and Mexican cuisines. By 1971 there was an inkling of a new movement towards cooking in America; fresh food simply prepared! The high priestess of this new way of preparing food was Chef Alice Waters at her restaurant Chez Panisse in Berkley, California. She Americanized Nouvelle Cuisine by rejecting processed package foods in favor of fresh, seasonal, organic produce, fish and meats all prepared to emphasize the food’s natural flavor thus creating The New American Cuisine.
Special Note: In America beginning in the early part of the 18th century, the American regional cuisine known as Cajun/Creole began to take root. With the arrival of the French, Spanish, Africans, Germans, English, Italians, and the Native Americans already here, America’s original regional cuisine evolved into a great art form of the New World.
Later other regional cuisines emerged:
• Tex-Mex
• Southern Soul
• Florida Cuisine
• Gee Chee and Gullah cuisine of the Carolinas
• Pacific Rim
• Appalachian Cuisine
• The Three Nations of Barbeque
• Texas
• Memphis
• The Carolinas
Americans in the 1950’s also developed a taste for fiery hot ethnic cuisines such as:
• Mexican Cuisine
• Hunan
• Szechuan
• Thai
• Korean | textbooks/workforce/Food_Production_Service_and_Culinary_Arts/Culinary_Foundations_(Cheramie_and_Thibodeaux)/01%3A_Professionalism_and_Saute/1.01%3A_History_of_Restaurants.txt |
The basic hierarchy of the classical kitchen brigade system is as follows:
• Chef de Cuisine – the head honcho, or executive chef, in charge of the entire kitchen (basically the general)
• Sous Chef – the under-chef, second in command. Supervises and coordinates the various station chefs (chef de parties). Second in command when the chef de cuisine is absent. Also acts as an expediter (aboyeur) during service (usually in training to become head chef)
• Chefs de Partie – various station chefs, which have responsibility for a certain part of meal, which are divided according to the ingredients they specialize in, or the method of cooking. A chef de partie usually has several demi-chefs (assistant station chefs) and commis (attendants) working under them.
Not all kitchens necessarily would have all the positions, but some of the following stations would be included:
• Saucier – sauté chef
• Poissonier – fish and shellfish dishes
• Friturier – fry chef prepares all fried items (basically deep frying)
• Grillardin – grilled and broiled foods
• Rotisseur – roasted and braised foods and any stuffing for them
• Potager – stocks and soups, assistant to the saucier. Considered a lower-skilled position.
• Legumier – vegetable dishes
• Entremeteir – this is a combined potager and legumier, preparing vegetable dishes, soups, and stocks
• Garde Manger – prepares or coordinates all cold foods including salads, cold meats, pates, terrines, sausages, hors d’oeurves, decorative carving garnishes, buffet items, if present.
• Boucher – butcher responsible for meat butchery, and poultry and fish treatment. May prepare these and then give them to the garde manger for distribution to the various station chefs.
• Charcutier – prepares pork products such as pâté, pâté en croûte, rillettes, hams, sausages, or any cured meats. May coordinate with the garde manger and deliver cured meats.
• Patissier – pastry chef
• Confiseur – makes petits fours and candies
• Glacier – makes cold or frozen desserts (today this would be someone who makes ice cream and other frozen desserts, and perhaps also makes ice sculptures.
• Decorateur – decorates cakes or other items
• Boulanger – baker, makes breads, rolls, and cakes
• Demi-Chef – assistant station chef. Does most of the actual preparation of the food in the specific station they are assigned, as supervised by the station chef (chef de partie). In charge of the station if the station chef is absent.
• Commis – attendants assigned to a particular station and given the grunt work, or lower-skill work. Usually in training to become a demi-chef.
• Apprentice – lowest man on the totem pole and given the heavy lifting work while studying the culinary arts and in training to become a commis and then move up from there. Works through all the various stations in order to become prepared to move up.
The Modern Kitchen Brigade
Modern restaurant kitchens, as mentioned, rarely use the classic brigade system. However, due to the large volume, you might find the classic system in use on large cruise liners or any place where a huge volume of food is prepared.
• Executive Chef – the top chef who manages everything to do with the kitchen, creates the menu, orders supplies, oversees the staff, communicates and reports to the owners and/or managers. Executive chefs may oversee more than one restaurant kitchen, as when there are several restaurants in a hotel or resort. Not all restaurants have a separate executive chef and chef de cuisine, defined below and an executive chef may spend much of his or her time cooking, instead of involved in administrative duties.
• Chef de cuisine – the kitchen chef who is the head chef of the kitchen. May report to the executive chef, or directly to the owner, if the owner maintains control of the kitchen. In some cases, the executive chef and the chef de cuisine may be the same.
• Sous chef – next in line under the chef de cuisine, same as the under chef in the classic system, and in command when the head chef (or executive chef, if applicable) is not present. Oversees the preparation, portioning, and presentation of the menu items according to the standards of the executive chef or chef de cuisine.
• Area chefs – these are basically the chefs de partie or station chefs, responsible for a particular area in the kitchen. Depending on how closely the kitchen follows the classic brigade, the station chefs may have line cooks under them, or line cook and station chef may essentially be the same position. Any of the positions of the classic system are possible, such as: saucier, poissonier, rotisseur, or grillardin, etc. and in modern kitchens, duties may rotate.
• Line cooks – works for the area chef and assigned a particular position in the assigned kitchen area.
• Expeditor – (aboyeur) takes orders from servers in dining room, announces them to the kitchen, and facilitates the efficient coordination of each dish. May make a final check on the finished plate and apply finishing touches. Makes sure the servers deliver the plates promptly and correctly, and may deliver orders themselves, in some cases.
There are many other positions possible in a kitchen, and there are also duties that have not been covered here, such as dishwasher and others, that are needed for the functioning of a busy kitchen.
Work Ethics of a Chef
Here is the reality check: if a person wants to pursue a career in food operations, he or she must understand that the commitment is unique. Yes, other careers do require a strong work ethic, but foodservice is unusual in that the requirement for work typically exceed what one would normally expect. It is what it is and will not likely change. Here is why: we work so that other people can play. This is our charge, this is what is required and is the nature of hospitality. Holidays are busy days in restaurants – there is no getting around it. Dinner happens after 5 p.m. when others are done for the day – this is the time when we gear up for a long night. Weekends are not for foodservice staff – in fact, our weekends are typically Monday and Tuesday, if at all. Accept it – this is what we are about. Food positions are not for the weak at heart. No matter what some might promote as a need to change, this is the reality of work in hospitality. Now, all that being said, those who can make that adjustment will share in the lifestyle of a unique, very special group of people who are hard-working and fun loving – people who are committed to service and do enjoy making others happy. Those who do not fit will move on to something else, those who stay are the heart and soul of the service business and the nurturers of others enjoyment. Work ethic in foodservice must include an understanding and acceptance of this.
Hire work ethic, be upfront with those who apply, enjoy the company of those who are willing to commit and celebrate the dedication that they have to the enjoyment of others.
Strong work ethic is the price of admission in food service.
Attributes of a Chef
A Thinker
Cooks and chefs are faced with analyzing situations and making decisions constantly. As much as the job of cooking is physical, it is just as mental. Determining timing, prioritizing steps, adapting to variables in the flavor profile of ingredients, troubleshooting staffing issues, and solving equipment issues requires sharp minds as well as accomplished hands.
Intelligent
Cooks possess an innate intelligence demonstrated through their ability to sift through various situations and factors that lead to rapid-fire decisions. As stated in the description above, cooks and chefs are consummate planners, masterful problem-solvers, highly creative artists, great students of food, and in possession of fine-tuned memories that allow them to keep multiple tasks and procedures close to their chest.
Inquisitive – Willing To Question
Serious cooks and chefs are constantly looking for the answer to “why”. It is this quest for answers that makes a cook better at his or her craft and a ‘chef’ able to meet the demands of the job.
A Dreamer
Although it is usually advisable for cooks and chefs to prepare food that customers are comfortable with, the culinary professional pushes the envelope and introduces food that we will learn to love and become excited about. This is what continues to allow restaurants to grow and remain significant.
Competitive
Great cooks are inherently competitive. Sometimes they focus on competition with other restaurants, other chefs, or even their peers, but the most successful cooks and chefs are primarily, in competition with themselves. “How can I improve? How can a dish that is well supported by guests become even better?”
Great cooks and chefs are never satisfied with how well they are performing today. They are always seeking to stay relevant and improve.
A Person with Unquestionable Work Ethic
To define a cook or chef as “serious” is directly relates to their commitment to the work. Great work ethic is second nature to great cooks. We might complain about the long hours and intensity of the work, but underneath we know that anything less is not enough. Total commitment to doing what is necessary is the essence of professional cooking.
Goal Driven
If the ultimate form of business assessment is results, then cooks and chefs should be the poster child. Some goals are small, while others might determine the longevity of a restaurant as a business, but to a cook they are all the same. A goal is a goal and it is their job to meet or exceed expectations.
Creative
Cooks are the consummate artists. Appealing to every human sense in a way that brings enjoyment is an everyday job for kitchen professionals.
Dependable
Frankly – no other part of a cooks profile is more important that his or her desire and total commitment to trust. To be a great cook or chef is to be dependable without exception. Trust that they are present and ready when needed, trust that quality will never be sacrificed, and trust that the best interests of the team and the operation are of paramount importance to every cook who carries the label of “serious”.
Antagonistic
The best cooks push others, critique others (while offering solutions), ensure that everyone remembers what the big picture is, and never turns his or her back on doing things right. He or she might be a thorn in other cooks sides, but they help to make everyone better at what they do.
A Rebel with a Cause
Unlike James Dean, the cook who is often seen as rebellious, pushy, crusty, hard, confrontational, and a real pain in the ass is really a proud professional. He or she helps to ensure that everyone remembers what they are in the kitchen to accomplish; respect the food; working as a team; producing exceptional food; pleasing the guest; and helping the restaurant to build a brand and reach its goals.
Your Best Friend or Your Worst Enemy
I have never found individuals who can fit the description of “friend” better than a cook who has learned to trust me. I have never found a higher level of commitment to friendship and respect than in the kitchen but at the same time, it would be hard to find someone more intent on taking another person down than a cook who feels that another has violated this trust or commitment.
Highly Organized
Without methodical organization in a kitchen you are only left with chaos. Since mise en place is at the core of what we do and the first skill that a cook learns, it only makes sense that serious cooks find that organization is the essence of what they do.
Protective
All for one and one for all – cooks are protective of other cooks. This level of protection may even go beyond the walls of an individual kitchen. If you wear whites then you feel support from anyone else who wears the uniform and stands before a range.
Street Smart
Those who are street smart are individuals who can separate truth from a line of bull, fact from fiction, honest from dishonest, opportunity from danger, and inherently good people from those whom you should avoid. I am not sure if it is the work of the kitchen or the diversity of characters that call it home – but most serious cooks that I know are as street smart as they come. This skill allows them to survive and thrive. A cook who is dedicated to the craft and street smart is more likely to become an effective chef/leader than one who lacks this breadth of experience.
In Touch with the Five Senses
Of course, unlike the vast majority of people, cooks are tactile artists who understand how to incorporate taste, touch, sight, smell, and sounds into the experience of eating food and dining in restaurants. Cooks are the complete artist package.
Tough but Tender
Crusty and tough as nails, serious cooks are tender underneath. They are emotional bandits who feel deeply, care wholeheartedly, and give more than they take.
A Fantastic Storyteller
Chefs, in particular, use their story making skills in numerous ways. Most significantly, a restaurant menu is a compendium of stories that depict a chef’s career and the impact that food and specific dishes have had on his or her life. Sometimes this is made obvious through a theme or stated philosophy, but even when this is not the case; the menu will reflect a chef’s comfort level with certain preparations and the stories behind them.
In a more obvious way, cooks and chefs accumulate stories of the kitchen (the good, the bad, and the ugly) over a period of years, and are always willing to share them with others. The longer that a cook spends in professional kitchens, the better he or she becomes at telling, and sometimes exaggerating these stories. It is these stories that serve to attract others to careers in the kitchen and fascinate those who dream about what it must be like to cook for a living.
Proud as Hell
Above all else – cooks are proud of what they do, what they are capable of, the people with whom they work, and the impact that they have on others. It is the chef’s greatest pleasure to point this out, shake hands with his or her team, hug those who give it all every day, and celebrate this pride every day with some of the best, most talented people anyone could know.
**This type of person is valuable, appreciated, respected, and on the road to success. BE THIS KIND OF COOK and watch how many doors open and how many opportunities come your way. | textbooks/workforce/Food_Production_Service_and_Culinary_Arts/Culinary_Foundations_(Cheramie_and_Thibodeaux)/01%3A_Professionalism_and_Saute/1.02%3A_The_Brigade.txt |
Knife skills are the single most important and the most fundamental skill a chef must acquire. Knife skills take repetition and practice to build speed and productivity. Good knife skills require an organized workstation, properly sharpened knives, and disciplined technique. The Chef Knife or French Knife is the single instrument with which you will spend the most time.
Gripping the Knife
A good grip will give you better control increasing cutting accuracy and speed, while preventing slippage and lessening the chances of accidents.
Handling the Knife
The best way to hold a chef knife is to grip the heel of the blade with your thumb and forefinger and wrap the remaining three fingers around the handle.
The Guide Hand
The purpose of the opposite hand is used for holding and guiding the food to be processed. Always curl the fingertips of the opposite hand into a ‘claw’ shape, never lay them flat. Use the second joint of the opposite fingers as a guide for the knife blade. This will help control the thickness of the cut. Slide the blade across the product. A sharp edge will allow the knife to glide through the object with minimal applied pressure.
Uniformity & Consistency
Consistency in shape and size is important for two reasons:
1. A uniform size will give the dish a better appearance.
2. Uniformity in size means the product will cook evenly.
Mise en Place
Bouquet Garni, Sachet d'epice
Mirepoix & Matignon
Other mise en place cuts would include:
• Minced garlic
• Minced parsley
• Tomato concassee
• Diced bell pepper
Standard U.S. Measurements (See Appendix for Additional Measures)
Unit Equals Also equals
1 teaspoon 1/3 tablespoon 1/6 fluid ounce
1 tablespoon 3 teaspoons 1/2 fluid ounce
1/8 cup 2 tablespoons 1 fluid ounce
1/4 cup 4 tablespoons 2 fluid ounces
1/3 cup 1/4 cup plus 4 teaspoons 2 3/4 fluid ounces
1/2 cup 8 tablespoons 4 fluid ounces
1 cup 1/2 pint 8 fluid ounces
1 pint 2 cups 16 fluid ounces
1 quart 4 cups 32 fluid ounces
1 liter 1 quart plus 1/4 cup 4 1/4 cups
1 gallon 4 quarts 16 cups/128 fl. oz.
1.04: Understanding Heat
A chef is more than someone who combines certain ingredients in a certain order – a true chef is a master of thermodynamics.
The Relationship between Heat Transfer and Cooking
Have you ever wondered what is actually happening when you are cooking food? While this is something that we usually take for granted, this process of heating food - known as heat transfer - is complicated and fascinating. Keep reading to learn more about the relationship between heat transfer and cooking and the important role it plays in your kitchen.
What is Heat Transfer?
Heat transfer is an exchange of thermal energy between two objects. The rate of heat transfer depends upon the temperatures of each entity and the medium through which the thermal energy is being transferred. In cooking, heat transfer refers to heating your food items through a cooking appliance, such as a stove, fryer, microwave, or oven.
How is Heat Transfer Used in Cooking?
Heat transfer is a very important aspect of the cooking process. Heating food destroys potentially harmful bacteria and other microorganisms, which makes food safe to eat and easier to digest. When food or liquids become hot, their molecules absorb energy, begin vibrating rapidly, and start to bounce off of each other. As they collide, heat energy is produced and transferred, which warms and cooks our food.
Methods of Heat Transfer
There are 3 types of heat transfer:
• Conduction
• Convection
• Radiation
Each of these methods features its own unique characteristics, but there is also some crossover between the different types.
What is Conduction?
Conduction is the process of heat being transferred between objects through direct contact, and it's the most common type of heat transfer. For example, in cooking the burners on stoves will conduct heat energy to the bottom of a pan sitting on top of it. From there, the pan conducts heat to its contents.
A deep fryer also uses conduction heating as the hot oil cooks the food when it comes into direct contact with it. Additionally, conduction heat is responsible for moving heat from the outside of the food to the inside. As a result, conduction heat also happens when cooking with convection and radiation heating methods.
Conduction is the slowest method of heat transfer, but the direct contact between the cooking surface and the item to be heated allows food to be cooked from the outside in. When cooking a steak in a cast iron skillet, for example, conduction produces an evenly cooked exterior and a moist, juicy interior that guests are sure to love.
Examples of Conduction Cooking
Here are a few examples conduction heating:
• Burning your hand on a hot piece of metal
• Grilling steak, chicken breasts, or pork chops
• Using ice water to blanch vegetables after steaming to keep them from losing their color
What is Convection?
Convection combines conduction heat transfer and circulation to force molecules in the air to move from warmer areas to cooler ones. As the molecules closest to the heat source become warm, they rise and are replaced by cooler molecules. There are two types of convection that are based on the movement of the heated molecules.
Convection combines conduction heat transfer and circulation to force molecules in the air to move from warmer areas to cooler ones. As the molecules closest to the heat source become warm, they rise and are replaced by cooler molecules. There are two types of convection that are based on the movement of the heated molecules.
Natural Convection
Natural convection occurs when molecules at the bottom of a cooking vessel rise and warm while cooler and heavier molecules sink. This creates a circulating current that evenly distributes heat throughout the substance being prepared.
For example, when a pot of water is placed on the stove to boil, conduction heat warms up the pot, which then heats the water molecules inside. As these molecules heat, convection causes them to move away from the interior of the pot as they are replaced by cooler molecules. This continuous current creates convection heat transfer within the water.
Mechanical Convection
Mechanical convection occurs when outside forces circulate heat, which shortens cooking times and cooks food more evenly. Examples of this include stirring liquid in a pot or when a convection oven uses a fan and exhaust system to blow hot air over and around the food before venting it back out.
Examples of Convection Cooking
Here are a few examples of how heat transfer via convection works:
• Water coming to a boil and circulating in the pot
• Running cold water over frozen food, which transfers heat into the food to thaw it more quickly
• Room temperature air moving around frozen food to thaw it
What is Radiation Cooking?
In cooking, radiation is the process where heat and light waves strike and penetrate your food. As such, there is no direct contact between the heat source and the cooking food. There are two main radiant heat cooking methods: infrared and microwave radiation.
Infrared Radiation
Infrared radiation utilizes an electric or ceramic heating element that gives off electromagnetic energy waves. These waves travel in any direction at the speed of light to quickly heat food, and are mainly absorbed at the surface of whatever you're preparing. Examples of things that create infrared radiation are glowing coals in a fire, toaster ovens, and broilers.
Microwave Radiation
Microwave radiation utilizes short, high-frequency waves that penetrate food, which agitates its water molecules to create friction and transfer heat. If you're heating a solid substance, this heat energy is transferred throughout the food through conduction, while liquids do so through convection.
Microwave heat transfer usually cooks food faster than infrared radiation, as it is able to penetrate foods several inches deep. Keep in mind that microwave radiation works best when cooking small batches of food.
Examples of Radiation Cooking
Here are a few examples of how heat transfer via radiation works:
• Warming your hands over a fire
• Lying in the sun to get warm
• Heating up dinner in the microwave
Whether you are using a pan on a stove, a convection oven, or a heavy-duty microwave, conduction, convection, and radiation are all around us. Knowing and understanding what heat transfer is, how it works, and which type of heat transfer is happening as you cook can help you better understand the science of cooking and improve your skills as a chef.
1.05: The Cooking Techniques - Saute
Sauté
Sauté is a French term, translated it means, “to jump”. It is a dry method of cooking that uses a relatively small amount of oil or fat in a shallow pan over relatively high heat. Various sauté methods exist, and sauté pans are a specific type of pan designed for sautéing. Ingredients for sautéing are usually cut into pieces or thinly sliced to facilitate fast cooking. The primary mode of heat transfer during sautéing is conduction between the pan and the food being cooked. Food that is sautéed is browned while preserving its texture, moisture, and flavor. If meat, chicken, or fish is sautéed, the sauté is often finished by deglazing the pan's residue (fond) to make a sauce. Sautéing differs from searing in that searing only browns the surface of the food. Certain oils should not be used to sauté due to their low smoke point. Clarified butter, rapeseed oil and sunflower oil are commonly used for sautéing;[8] whatever the fat, it must have a smoke point high enough to allow cooking on medium-high heat, the temperature at which sautéing is done. For example, though regular butter would produce more flavor, it would burn at a lower temperature and more quickly than other fats due to the presence of milk solids. Clarified butter is more fit for this use. In a sauté, all the ingredients are heated at once, and cooked quickly. To facilitate this, the ingredients are rapidly moved around in the pan, either by the use of a utensil, or by repeatedly jerking the pan itself. A sauté pan must be large enough to hold all of the food in one layer, so steam can escape, which keeps the ingredients from stewing, and promotes the development of fond.
Sautéed Leeks. The Sauté Toss. Wikipedia. Commons | textbooks/workforce/Food_Production_Service_and_Culinary_Arts/Culinary_Foundations_(Cheramie_and_Thibodeaux)/01%3A_Professionalism_and_Saute/1.03%3A_Knife_Skills.txt |
Thumbnail: Braised ox cheek in star anise and soy sauce. (CC BY-SA 2.0; Alpha via Wikipedia)
02: Recipe conversions and Braising
Scaling a recipe means that you are adjusting the ingredient quantities for a different amount of servings. While doubling or halving a recipe is relatively easy, you will need to do some math when you want to convert a six-serving recipe for two people or 14 people. Whether you're increasing a recipe or decreasing it—the procedure for adjusting the ingredient quantities is the same.
The first step is to determine a conversion factor. Next, you need to multiply this number by the ingredient measurements.
Determine the Conversion Factor
The conversion factor is a number you are going to use to convert all the quantities. There is a bit of math involved, but it is perfectly fine to use a calculator to do the math calculation. To find your conversion factor, simply divide the desired number of servings (what you want) by the original number of servings (what you have). The resulting number is your conversion factor.
Here is the formula:
$\dfrac{\text{Desired servings}}{\text{original servings}} = \text{conversion factor} \nonumber$
For example, to scale a 10-serving recipe down to six portions: Divide 6 (desired servings) by 10 (original servings), which gives you a conversion factor of 0.6.
Applying the Conversion Factor
Once you determine the conversion factor, you need to multiply each ingredient measurement in the recipe by this number. In the example above, you would multiply each ingredient amount by 0.6.
Use this simple example to illustrate the calculations. Say your recipe calls for 2 quarts of chicken stock. All you need to do is multiply 2 quarts by your conversion factor of 0.6:
2 quarts × 0.6 = 1.2 quarts chicken stock
Converting the Measurements to Make Sense
As you see from the example, you are often left with a result that includes a decimal. You are in good luck if it is any of these numbers:
• 0.25: One quarter
• 0.33: One third
• 0.50: One half
• 0.66: Two thirds
• 0.75: Three quarters
When you have other numbers that result, such as the 0.2 of the 1.2 quarters, you can either try to ‘eyeball’ it or you can make a more precise conversion. The eyeballing route works fine for many types of cooking but can produce a flop if you are baking, where exact measurements are more important.
While the rest of the world uses the metric system, those in the U.S. will need to convert 1.2 quarts into ounces. Consulting a cooking conversion chart, you will learn that there are 32 ounces in a quart, so:
32 × 1.2 = 38.4 ounces
You can round that down to about 38 ounces, but that's still kind of a weird amount. It would be more clear if it were given in cups. Go back to the cooking conversion tool to find that there are 8 ounces in a cup, so:
38 ÷ 8 = 4.75
Which means 1.2 quarts is equal to approximately 4 3/4 cups, a much more doable number.
Do not worry this is going to take a long time or a lot of research. Not every ingredient is going to need multiple conversions. Many will be close to the easier decimals and you can use a half-cup, 2/3 cup, or other measures.
When Portion Sizes Change
Suppose that you are working with a book of standardized recipes. These types of recipes will produce a known quantity and quality of food. In addition, suppose you work for a fine catering company and a customer wants you to serve a six-ounce serving of jambalaya for a 284 guests, sit down dinner. Your standardized recipe is for 100, 4 oz. servings. What are you going to do so that you do not run out or produce too much? Convert the recipe by first obtaining the Conversion Factor:
1. Determine the total yield of both amounts:
284 X 6 = 1704
100 X 4 = 400
2. Divide what you want by what you have:
1704 divided by 400 = 4.26, your conversion factor.
3. Every ingredient in the standardized recipe is multiplied by 4.26, and then cook the jambalaya by the recipe directions.
2.02: The Cooking Techniques - Braising
Braising
Braising (from the French word braiser) is a combination-cooking method that uses both wet and dry heats: typically, the food is first sautéed or seared at a high temperature, then finished in a covered pot at a lower temperature while sitting in some (variable) amount of liquid (which may also add flavor). Braising of meat is often referred to as pot roasting, though some authors make a distinction between the two methods, based on whether additional liquid is added. Braising relies on heat, time, and moisture to break down the tough connective tissue (collagen) that binds together the muscle fibers collectively called "meat", making it an ideal way to cook tougher, more affordable cuts. Many classic braised dishes (e.g., coq au vin) are highly evolved methods of cooking tough and otherwise unpalatable foods. Both pressure cooking, and slow cooking (e.g., crockpots) are forms of braising.
Most braises follow the same basic steps.
• The food to be braised (meats, vegetables, mushrooms, etc.) is first pan-seared to brown its surface and enhance its flavor (through the Maillard reaction).
• If the food will not produce enough liquid of its own, a certain amount of cooking liquid that often includes an acidic element (e.g., tomatoes, beer, balsamic vinegar, wine) is added to the pot, often with stock. A classic braise is done with a relatively whole cut of meat, and the braising liquid will cover one-third to one-half of the food in the pan.
• The dish is then covered and cooked at a very low simmer until the meat becomes so tender that it can be "cut" with just the gentlest of pressure from a fork (versus a knife).
• Often the cooking liquid is finished to create a sauce or gravy as well.
Pot Roast. Wikipedia. Commons cc-by 3.0 | textbooks/workforce/Food_Production_Service_and_Culinary_Arts/Culinary_Foundations_(Cheramie_and_Thibodeaux)/02%3A_Recipe_conversions_and_Braising/2.01%3A_Recipe_Conversion.txt |
• 3.1: Mise en Place
Perhaps you have heard the saying, “Prior preparation prevents poor performance.” It is a memorable saying that reminds us that if we want to be successful, we must first spend time preparing for the task at hand. This principle is essential in commercial kitchens. When serving a wide variety of dishes to several people a day, preparation is crucial to success. In fact, preparation is a key principal in professional kitchens, and it has a name: Mise en place.
• 3.2: The Cooking Technique - Stewing
This is a slow-cooking method, similar to braising, with the key difference being the meat is covered in liquid. Stewing is best done in a heavy stockpot or Dutch oven on the stovetop or in the oven, or in a slow-cooker.
Thumbnail: Stew (Unsplash License; Nathan Dumlao via Unsplash)
03: Lab - Mise en Place
Perhaps you have heard the saying, “Prior preparation prevents poor performance.” It is a memorable saying that reminds us that if we want to be successful, we must first spend time preparing for the task at hand. This principle is essential in commercial kitchens. When serving a wide variety of dishes to several people a day, preparation is crucial to success. In fact, preparation is a key principal in professional kitchens, and it has a name: Mise en place.
Four Essential Steps of Mise en Place:
• Assemble tools
• Assemble ingredients
• Wash, trim, cut, prepare and measure raw materials
• Prepare equipment (pre-heat oven or pan, line sheet pan with parchment, etc.)
What is Mise en Place?
Mise en place (rhymes with “cheese on sauce”) is a French term that literally means to put in place. It describes all of the advance preparation that takes place in the kitchen before the doors open for business. For every dish on the menu, the chef gathers, prepares, and organizes all the necessary ingredients. Vegetables are chopped. Salad greens are washed. Sauces and stocks are prepared. Cuts of protein are trimmed and portioned. The chef also gathers and organizes all the necessary tools he will need once the meal service period begins. When he completes his mise en place, the chef should have everything he needs within reach to assemble every dish at his station. There is no time during the lunch or dinner rush to stop and prepare an ingredient you need for a dish. Let’s say you have a strip steak on your menu served with a bearnaise sauce. If you failed to make enough sauce during your mise en place, you will not be able to sell that dish. What happens when you run out of that sauce and you still have three steak orders to fill? Some of your guests are going to walk away disappointed.
A State of Mind
Mise en place is more than just preparation; it is a state of mind. In the previous example, either the chef did not anticipate the number of steak orders that night, or he miscalculated the amount of sauce needed. Understanding the concept of mise en place means anticipating what tasks need to be accomplished and in what order. It is the ability to be proactive rather than reactive. The chef who masters the practice of mise en place is the chef who is in control of the kitchen. The kitchen is not in control of him. Various external elements, both big and small, can help your “mise en place state of mind”. Looking professional by wearing a proper, clean, wrinkle free uniform and headwear can go a long way to a proper state of mind. Getting your station ready for service is crucial, but so is keeping it clean and organized throughout service. A messy, unorganized station denotes a messy, unorganized mind! Clean-as-you-go principles are crucial to maintaining a proper state of mind, and thus, proper mise en place.
Control the Chaos
"Mise-en-place is the religion of all good line cooks...As a cook, your station, and its condition, its state of readiness, is an extension of your nervous system". - Anthony Bourdain
Every foodservice establishment has to solve the conflict; there is too much work to be done to wait until the last minute and most foods are at their peak of quality immediately after preparation. Mise en place solves the conflict!
Chefs start their work early in the day to prepare their mise en place for service. The goal is to do as much work in advance without loss of quality so that at service time all energy can be focused on putting out a fresh quality product! This preparation covers everything from cutting vegetables, preparing garnishes, making sauces, and cooking ingredients sous-vide. When dinner service begins, the chefs can then arrange and assemble each dish quickly. If the mise en place is organized and every ingredient is covered, a chef should be able to assemble their dish blindfolded, since each ingredient is consistently placed in the same spot. Absence of proper mise en place insures that chaos will reign.
The Big Picture
While the organization of one’s self and station allowing for timely preparation and service is important, it does not stop there. Front of the house management should follow mise en place principles for better service. Successful office management, overseeing purchasing, inventory, cost control, payroll etc., will utilize mise en place principles every day whether they realize it or not! If they did not, they would not be successful! Complete interaction of the back of the house, front of the house, and management is required for complete mise en place and a successful foodservice operation.
If restaurants are the definition of controlled chaos, mise en place controls the chaos!
3.02: The Cooking Technique - Stewing
Stewing Basics
This is a slow-cooking method, similar to braising, with the key difference being the meat is covered in liquid. Stewing is best done in a heavy stockpot or Dutch oven on the stovetop or in the oven, or in a slow-cooker.
Dredging food. flicker.com
CUT & DREDGE
If you're using pre-packaged (or cutting your own) chunks, make sure they're not too small to prevent overcooking. Aim for cubes about the size of a golf ball. Many stew recipes call for dredging the meat in seasoned flour before browning.
BROWN THE MEAT
Heat a drizzle of oil in the pan over medium heat and brown the meat on all sides, and drain (unless your recipe says to leave the drippings). You may need to work in batches if using a smaller pan. If you're using a slow cooker, transfer it over.
ALL TOGETHER NOW
Depending on your recipe, now's the time to add seasonings, vegetables and liquid — such as beef broth, wine, beer, juice or even water. Bring the liquid to a boil, then reduce heat to low and cover with a tight-fitting lid.
SIMMER & STEW
Use a tight-fitting lid and keep it on while stewing to prevent moisture and heat loss, which can affect cooking time. Follow your recipe for timing guidelines. Do not lift the lid — unless you are recipe calls for adding vegetables or other ingredients later on. You will know it is done when the meat is fork tender.
Cowboy Beef Stew. beefitswhatsfordinner.com | textbooks/workforce/Food_Production_Service_and_Culinary_Arts/Culinary_Foundations_(Cheramie_and_Thibodeaux)/03%3A_Lab_-_Mise_en_Place/3.01%3A_Mise_en_Place.txt |
Thumbnail: Grilling chicken (Unsplash license; Dustin Tramel via unsplash)
04: Food Presentation Standards and Grilling
Customers Eat With Their Eyes First
First impressions set customer expectations. Good impressions stimulate the appetite and get digestive juices flowing. Carelessly presented food usually means carelessly cooked and shows the customer that the chef has no regard for his food or his customer! Usually, what you see is what you get. Well presented food gets the customer excited before he takes the first bite!
Attractive food is a hallmark of professionalism
Creative and thoughtful plating enhances both the look and taste of your food. Focusing on presentation also allows chefs to showcase their creations and demonstrate to guests that they're getting their money's worth. While there aren't any hard and fast rules when it comes to "correct" plating, there are several important concepts to keep in mind as you prepare and present your restaurant's delicious culinary creations.
Professional chefs look at their creations with the eyes of an artist:
• Balance – food that taste good together and offer variety and contrast
• Color – two or three are more interesting that one (said to be monochromatic).
• Shapes – knife skills can offer a variety of shapes
• Texture – something chewy with something crispy, and something smooth or creamy. Different mouth feels stimulate the mind.
Guidelines for Plating Food
For tips and tricks on how to create a beautiful plate, consider the steps below:
Choose the Perfect Plate
Selecting the right plate for your meal is key to attractive food presentation. Here are some things to keep in mind:
• Choose the right plate. One way to conceptualize plating is to think of yourself as an artist, the plate as your canvas, and the food as your medium.
• Choose the right size plate. Choose your plate wisely by making sure it is big enough to allow your food to stand out, but small enough that your portions do not look too small.
• Choose a complementary plate color. The color of your plate is also significant. White plates are popular because they create high contrast and provide a neutral background for your colorful creations. Utilize white space by thinking of the rim as your frame, and consider using the rule of thirds to highlight your plate's focal point(s). When applied to cooking, the rule of thirds prescribes placing the focal point of your dish to either the left or right side of the plate, rather than the center.
Placing Your Ingredients
Here are a few of the most important aspects to consider as you build your dish:
• Plate with a clock in mind. As you begin plating your ingredients, picture the face of a clock. From the diner's point of view, your protein should be between 3 and 9, your starch or carbohydrate from 9 and 12, and your vegetable from 12 and 3.
• Use moist ingredients as your base. Another rule of thumb is to plate moist or runny ingredients first, as they tend to move during delivery if they are not held down by other foods. One way to anchor runny ingredients is by placing other foods on top of them. For example, you can angle sliced meat or vegetables against purees and mashed vegetables.
• Serve odd amounts of food. If you are serving small foods like shrimp, scallops, or bite-sized appetizers, always give guests odd quantities. Serving seven Brussels sprouts instead of 6 creates more visual appeal, and diners will also perceive that they're getting more food.
• Place food to create flavor bites. Essentially, flavor bites are forkfuls of food that combine all of the ingredients in your dish into one bite. Creating flavor bites is the perfect accompaniment to creative plating as it pleases both the eye and the taste buds.
• Do not overcrowd your plate. Be sure to never overcrowd your canvas, and keep it simple by focusing on one ingredient - usually the protein. Finding a focal point also ensures that the accompanying ingredients will play a complementary, supporting role.
Pay Attention to the Details
As you ‘plate’ your dish, you will also want to pay attention to the details:
• Think about color and contrast. One of the best-kept secrets to beautiful plating is paying close attention to the details. While your focus will obviously be on the protein, considering how the other elements of the plate create color and contrast is also very important.
You can create a beautiful background for your plate by adding green vegetables or brightly colored fruits as accent points. Similarly, try to pair ingredients with complementary colors, as this will further enhance your dish's visual appeal.
• Create height on your plate. Another way to catch your guests' eyes is to utilize the power of height. While compactly stacking ingredients is not as popular as it was 5-10 years ago, creating a tall plate can go a long way towards enhancing visual appeal.
You can also balance out taller ingredients by leaning long, flat items against them. For example, you can plate your steak on top of polenta and lean asparagus spears against them at a 45-degree angle.
• Use texture to enhance your dish. Finally, don't forget about texture. Contrasting a smooth vegetable puree with crunchy onion straws or topping a steak with crumbled blue cheese creates appealing texture combinations that are classic in high-end cuisine.
Design and Create with Sauces
Once you've plated your main ingredients, you're ready to top your dish with delicious sauces. Don't just pour the sauce carelessly all over the plate, though. Instead, think of your squeeze bottle or spoon as a paintbrush, and your sauce as a medium. Then, use them to enhance your plate.
One way to do this is to create accent dots on one side of your plate (while considering the rule of thirds) or by lightly drizzling sauce over the main ingredients so guests get a little bit of sauce in every bite.
Use Garnishes Purposefully
In the past, chefs casually threw a piece of kale and an orange slice onto every plate as it left their kitchen. However, these garnishes did not add anything exciting to the dish, and few guests even ate them in the first place. Here are a few examples of smart garnishes and how to incorporate them:
• Choose edible garnishes. As you finish plating, remember that garnishes must be related to the dish and should always be edible. Ultimately, they are designed to enhance and complement the flavors of the entree you have created, not distract from them.
• Place garnishes purposefully. Similarly, never heap garnishes in one corner of the plate. Instead, disperse them thoughtfully in order to add color or texture. Also, avoid using unappetizing garnishes like raw herbs, large chunks of citrus, and anything with a strong odor. Lastly, make sure your garnishes are quick and easy to apply, so food still goes out piping hot. | textbooks/workforce/Food_Production_Service_and_Culinary_Arts/Culinary_Foundations_(Cheramie_and_Thibodeaux)/04%3A_Food_Presentation_Standards_and_Grilling/4.01%3A_Food_Presentation.txt |
Having the proper food presentation and plating tools is essential to high-quality plating. Here are a few items you should be sure to purchase if you do not already own them:
Decorating Brushes
As one of the most important products in any chef's toolkit, decorating brushes have a variety of applications. You can use them for both detailed line work and broad strokes as you apply sauces, or when plating purees and coulis beneath meat or vegetables.
Garnishing Kits
Garnishing kits come with everything you need to garnish all of your signature dishes, including plating wedges, tongs, squeeze bottles, and brushes.
Molds
Molds are also very important when plating food. By cutting ingredients to a specific shape and size, you'll provide visual appeal and keep your plate tidy. Ring molds also help you develop height and structure when stacking ingredients.
Plating and Precision Tongs
Last but not least, you'll want to have precision tongs on hand for placing garnishes or small, delicate foods. Many tongs also feature micro-serrations for improved grip and stability
Plating Wedges
Plating wedges come pre-cut with flat, round, or pointed edges and are perfect for smearing sauces and other soft ingredients into designs on your plate.
Shavers
Shavers work well when shaving or grating chocolate, hard cheeses, or soft vegetables on top of your finished creations.
Spoons
You will also want to have a variety of spoons on hand. Saucier spoons help you drag smears of sauce across your plate, and you can choose a utensil with a tapered bowl that is perfect for drizzling and pouring. Additionally, slotted spoons quickly separate solids from liquids as you complete your presentation.
Squeeze Bottles
Squeeze bottles are ideal when applying sauces or aioli to your finished plate. Many of these items come with adjustable, precision control tips that allow you to apply the perfect amount of product.
Saying all that, the single, most important thing a chef can do to make sure his food looks and tastes good is to simply cook it right!
4.03: Plating Examples
Examples of Plating Styles
Here are examples of three popular plating styles: classic, free form, and landscape. To demonstrate them, we used filet mignon, potato puree, carrots, a demi-glace, a pea puree, a lima bean and pea blend, thyme, and fried leeks.
Classic Plating
1. Pipe the potato puree onto the plate using a pastry bag.
2. Place the carrots next to the puree using precision tongs.
3. Garnish the carrots with thyme using precision tongs.
4. Plate the steak using precision tongs.
5. Garnish the steak with fried leeks using precision tongs.
6. Drizzle the demi-glace around the plate using a spouted saucier.
7. Wipe the edges of the plate with a clean towel.
8. Finished classic plate.
Free Form Plating
1. Pipe dots of potato puree onto the plate using a pastry bag.
2. Slice the steak into three pieces using a chef's knife.
3. Plate the pieces of steak using precision tongs.
4. Place the lima bean and pea blend around the plate using a spoon.
5. Plate the carrots using precision tongs.
6. Place dots of pea puree around the plate using a large squeeze bottle.
7. Place dots of the demi-glace around the plate using a small squeeze bottle.
8. Garnish the plate with fried leeks using precision tongs.
9. Wipe the edges of the plate with a clean towel.
Landscape Plating
1. Place dots of pea puree around the plate using a large squeeze bottle.
2. Paint the pea puree onto the plate using a brush.
3. Pipe the potato puree onto the plate using a pastry bag.
4. Plate the carrots using precision tongs.
5. Lean the steak against the puree and carrots using precision tongs.
6. Place the lima bean and pea blend around the plate using a spoon.
7. Drizzle the demi-glace around the plate using a spouted saucier.
8. Garnish the steak with fried leeks using precision tongs.
9. Wipe the edges of the plate with a clean towel.
10. Finished landscape plate.
Whether a fine dining establishment, upscale restaurant, or eclectic cafe, thoughtful and attentive plating is sure to improve customers' impressions of any foodservice operation. An awareness of food presentation also allows chefs to demonstrate their chefs' skills to customers and helps them highlight all of their restaurant's delicious offerings. With an awareness of these basic principles, techniques, and tools, chefs are sure to enhance plating and increase sales.
4.04: The Cooking Techniques - Grilling
Basic Grilling Techniques
There are multiple grilling techniques and methods. The types of heat sources for grilling are numerous. Factor in the different types of food like steaks, poultry, fish, seafood and vegetables and you can quickly see that the ways and methods of grilling are going to be many and diverse.
The key is to CUSTOMIZE your grilling techniques and your use of equipment to suit the food type to obtain the result you desire. To get the best results from a particular method or technique, these factors have to enter into play.
The main factors are food type, heat source and desired result. The last factor has to do with personal preference or weather. For example, will you be grilling indoors or outdoors?
Grilling Methods
Direct heat grilling is the most basic and common grilling method. The words speak for this method. Food items are placed over direct heat in order to cook them. This can be done over a charcoal, gas, wood or any other heat source.
The heat is usually high and ideal for SEARING. Searing involves using high heat to 'burn' both sides of your food item for a few minutes to seal flavors. The thicker your meat the longer you can sear.
After searing, the food item can then be transferred to the 'not-so-hot' part of the grill to cook.
Hamburgers, steaks, chops, sausages even kabobs do well with direct heat. These foods usually take 30 minutes or less to be fully cooked.
Indirect grilling is a method where the food is cooked with reflected or indirect heat. It involves not placing the food over a direct heat source and keeping the lid covered most of the time.
If the food must be placed over the heat source then the temperature will have to be low for the food to cook 'indirectly'. It is like roasting in an oven. Large pieces that take a while to cook like whole turkeys, leg of lamb and many roasts can be cooked in this way.
Sometimes food items are grilled over direct heat first, to seal flavors, and then they are cooked with indirect heat.
Diamond Grill Marks
1. Preheat grill until very hot (about 500 – 550°F).
2. Season steaks with salt and pepper, or as desired.
3. Place steaks on preheated grill with the ends at 10 and 4 o’clock.
4. When meat has seared and juices begin to rise to the top, turn steaks clockwise, with the ends at 2 and 8 o’clock.
5. After a minute or two, flip steaks over and cook until they reach desired degree of doneness. Use a meat thermometer if necessary.
6. Remove steaks from grill onto clean plate and allow them to rest approximately 5 minutes to redistribute the juices.
Steak with proper cross - hatch marks. gorare.com | textbooks/workforce/Food_Production_Service_and_Culinary_Arts/Culinary_Foundations_(Cheramie_and_Thibodeaux)/04%3A_Food_Presentation_Standards_and_Grilling/4.02%3A_Plating_Tools_of_the_Trade.txt |
Thumbnail: Steaming Dim sum (Unsplash license; Thom Milkovic via unplash)
05: Emulsions and Steaming
There is no doubt about it–emulsions are tricky. They are confusing to understand and they are confusing to make. Sometimes even the most seasoned chef can have trouble getting their sauces to emulsify! However, if you can start to get a feel for the science behind the scenes, you will feel more in control and confident next time you decide to whip up a hollandaise sauce for Sunday brunch.
At its most basic, an emulsion is a suspension two liquids within each other that would not naturally mix.
Think of a liquid–a cup of vinegar, for instance–as made up of millions of tiny droplets. If you pour oil into the vinegar, at first the oil will float on the top of the vinegar because it is less dense. However, if you whisk them together, the tiny droplets forming each liquid start to mix together and become suspended within each other. This is an emulsion. The mixing of two ‘unmixable’ liquids held in suspension.
However, this simple vinaigrette will eventually separate back into vinegar and oil because, at a chemical level, there is nothing holding the drops of each liquid together except for the temporary confusion of having been whisked together.
To get a stable, permanent emulsion, you need to use something to hold the drops of opposing liquid together and prevent them from separating. This “something” is called an emulsifying agent or emulsifier. Moreover, this agent is like a mutual friend who holds the oil-based liquid in one hand and the water-based liquid in the other. It creates a chemical bond with each liquid and becomes a bridge between them.
The most common emulsifying agent is an egg yolk, as in mayonnaise and hollandaise sauces. Two others are the casein found in butter and the fine particles of ground dry mustard. Thick liquids such as Dijon mustard and honey can also act as emulsifiers.
Whisking a vinaigrette, thecookful.com
5.02: The Cooking techniques - Steaming
Steaming
Dim Sum (Chinese steamed buns). thespruceeats.com
When steaming, food is actually cooked at a higher temperature compared to poaching, braising, and stewing. Once water is heated past the 212 F mark, it stops being water and turns into steam. Steaming has an advantage over methods such as boiling or even simmering in that there is no agitation involved, so it is gentler on delicate items like seafood. Because it doesn't require the food to be submerged, it avoids the loss of nutrients through leaching. It also cooks relatively quickly.
Interestingly, steam's maximum temperature is also 212 F, just like water. However, unlike water, steam can be forced to exceed this natural temperature limit by pressurizing it. The higher the pressure, the hotter the steam becomes. Cooking with pressurized steam requires specialized equipment, though, which is typically not available to the beginner cook.
Cooking With Steam
Steaming can be done on a stovetop with two simple pieces of equipment: a pot and a steamer basket. The pot is filled with a small amount of liquid that is brought to a simmer; the item to be cooked is placed in a basket suspended above the liquid, and the pot is then covered. The hot steam circulates through the pot and cooks the food very quickly. This technique is known as "compartment steaming." (The bamboo steamers used in Asian cuisine are an example of a compartment steamer.)
It is important that the bottom of the steamer basket does not touch the simmering water; this would add too much moisture to the vegetables and would not steam them correctly.
You can also steam food in the microwave, which is actually a natural piece of equipment for steaming since it "excites the liquids in food." You can create your own steaming system by placing the food in a microwave-safe dish, sprinkling it with water or other liquid, and covering with plastic wrap with a few holes poked into it. Cook for just a few minutes and you will be rewarded with perfectly steamed food. You can also buy a steamer basket made just for the microwave if you find yourself using this method often.
Steaming Vegetables
Until oven-roasting and grilling vegetables came into fashion, steaming was the primary way home cooks prepared their veggie side dishes. Too often, however, the vegetables were left as is after cooking, leaving them bland and flavorless. On the other hand, worse, the vegetables were steamed for too long, resulting in a pile of tasteless, dark-colored mush.
Nevertheless, vegetables—including potatoes—benefit from being cooked with steam when done properly. Some vegetables like broccoli and cauliflower can turn soggy when simmered, so steaming is an excellent alternative cooking method. Steaming can also be a good first step to cooking certain vegetables an alternative way; for example, steaming broccoli before adding to a quick-cooking stir-fry will assure they finish with a crisp-tender texture. In addition, steaming potatoes before being sliced and placed on the grill will shorten their grilling time tremendously.
Steaming Fish and Shellfish
Seafood is particularly well suited for steaming. With compartment steaming, the cooking liquid (usually a broth, stock, or wine to add flavor) along with aromatic herbs, are gently simmered, creating flavorful steam. The moist environment inside the steamer compartment helps keep the fish tender and juicy.
Seafood can also be steamed in its own juices. Mussels are frequently cooked in a large, covered pot with a very small amount of wine. As the pot heats up, the mussels cook in the steam created from their own juices, which then combines with the wine and other ingredients to create a flavorful sauce.
Cooking EN PAPILLOTE
Another technique for cooking with steam is known as cooking EN PAPILLOTE ("in paper") or in packets. This method is frequently employed for cooking fish and involves enclosing the food in a pouch of parchment paper or aluminium foil along with a little liquid (often wine) and perhaps lemon, herbs, and even thinly sliced vegetables. The packet is then heated—in an oven or on a grill—so that the food inside cooks in its own steam.
Fish en papillote with lemon & herbs, www.loveandoliveoil.com
Health Benefits of Steaming
Besides being a simple cooking method, steaming is also a healthy way to prepare food. Compared to most other cooking methods, steaming preserves up to 50 percent more nutrients in the foods, and does not require any fats when cooking. This makes steaming an ideal cooking technique when you are watching your calorie and fat intake. Just do not forget to season!
Home Steamer Commercial Steamer | textbooks/workforce/Food_Production_Service_and_Culinary_Arts/Culinary_Foundations_(Cheramie_and_Thibodeaux)/05%3A_Emulsions_and_Steaming/5.01%3A_Emulsions.txt |
• 6.1: A True and Delectable History of Creole Cooking
• 6.2: Roux
Roux is a base sauce in international cuisines, originally French, composed of varying ratios of flour and fat (usually butter), useful for making sauces, and for thickening soups or gravies. The benefits of using a roux include the following: It does not have to cook very long to remove a floury taste, clumps of flour are removed, and it creates unique flavors. It can be cooked to different degrees.
Thumbnail: Bright and tantalizing seafood boil with crab, shrimp, and the fixins. (Unsplash License; Sunira Moses via Unsplash)
06: Cajun Creole Cuisine and Roux
A True and Delectable History of Creole Cooking
Bethany Ewald Bultman, December 1986, Volume 38, Issue No. 1
New Orleans cuisine—with its French roux, African okra, Indian filé, and Spanish peppers—is literally a gastronomic melting pot. Here’s how it all came together.
Bethany Bultman
Across most of America nowadays the term Creole when applied to food variably conjures up images of charred, blackened fish and meat, overbearing, fiery seasonings, and a ubiquitous red sauce not unlike the kind you buy in a can. As a seventh-generation native of south Louisiana, and as a food writer, I join other locals in feeling a twinge of horror at what has befallen my native cuisine since it became the food fad of the eighties. The dishes for which people happily wait in line outside the local Cajun/Creole guru Paul Prudhomme’s K-Paul’s Louisiana Kitchen—and for which they gladly pay high prices in restaurants from New York to San Francisco—would shame the men and women who toiled to create America’s preeminent native cuisine. Remaining virtually unnoticed by the majority of the new wave of Creole food fanciers are the Creole delights we have enjoyed for generations: succulent oyster patties, hogshead cheese, trout meunière, mirliton stuffed with crabmeat, and daube glacé.
It is a popular misconception that the terms Creole and Cajun are interchangeable. While there are similarities, Creole is the sophisticated, worldly urbanite and Cajun is the provincial country cousin. The inhabitants of New Orleans created Creole cuisine, a subtle group of dishes utilizing spices and rich sauces. The Cajuns, having settled later in more remote areas of the Louisiana countryside, had to improvise with ingredients readily available in the bayous.
Creole and Cajun cuisine did not develop in a linear way from French gastronomy to the same extent that American cooking derived from the English and European cooking styles of the seventeenth and eighteenth centuries. Louisiana cuisine, whatever it might be called, is the literal melting pot of America. In a pot of gumbo served today in a traditional New Orleans house, there is a French roux, African okra, Indian filé , Spanish peppers, Cajun sausage, and oysters supplied by a Yugoslav fisherman, all served over Chinese rice with an accompaniment of hot French bread made by one of the city’s finest German bakers.
This harmonious cuisine, born out of the mixture of cultures, evolved because of Louisiana’s geographical isolation, plus its settlers’ hardships, pride, instinct, and the Latin cultural desire to eat well. For two centuries, Creole cuisine kept changing to satisfy the needs and tastes of each new group who came to settle in Louisiana. Nowadays, starting with breakfast, with its calas (rice cakes) served with cane syrup, all the way through to the after-dinner treats of café brûlot and pecan pralines, the inhabitants of south Louisiana happily eat a unique diet.
From the rash of articles and cookbooks extolling the merits of Creole and Cajun food, it appears that the early seventeenth-century French settlers possessed such extraordinary culinary acumen that all they needed was an introduction to a few Indian herbs, a Spanish spice or two, and voilà, within a few years Louisiana had a legendary cuisine. Although almost any person in Louisiana of French ancestry will probably serve up this theory, it is not exactly the way things happened. Except for the kindness of the Indians, who were adept at living off the land, the French would have starved.
La Nouvelle Orleans was founded in 1718 by the French Canadian Jean-Baptiste Le Moyne, Sieur de Bienville, on a Muskhogean tribal portage at a strategic crescent on the Mississippi River, thirty leagues upriver from the Gulf of Mexico. The actual site was a small, verminous swamp, an area that is marked on maps of the period as being inhabited by “Savage Man Eaters.”
For a time the Compagnie des Indes, which controlled Louisiana, decided to colonize the area from the jails, brothels, and debtors’ prisons of France. The colony was in such chaos that the regent, Philippe of Orleans, finally put a stop to the practice in 1720. Early on, the unfortunate settlers discovered that the staple of their diet, wheat, would not grow in swampy, humid Louisiana. In spite of the fact that they named Lake Pontchartrain after the French minister in charge of providing them with staples; the settlers went for as much as two years without a shipment of flour.
If it had not been for the kindness of the Indians, the French would have starved. These Indians were adept at living off the land. They cultivated corn, from which they made a variety of breads; many kinds of squash, including the chayote (mirliton) and cushaw that are still popular in Louisiana today; and dried beans. They made sweet syrups from persimmons and chokecherries as a flavoring for smoked meats. Their stews were thickened with powdered sassafras, today called filé powder.
Most of the early French settlers were unwilling to live on Indian foods, and it became crucial to the survival of the colony that the Compagnie des Indes find some sturdy farmer immigrants who might be able to grow something for the French settlers to eat. Parts of Germany and Switzerland were inundated with handbills promoting Louisiana as a “paradise.” As a result, several hundred German settlers had been lured to the area by 1721. Quickly realizing that New Orleans, “the Paris of the New World,” was hardly an idyllic place to farm, they preferred to settle twenty miles upriver in an area known as the Côte des Allemands, away from the mildew and malaria of the city. The Germans did their job well, supplying the city with fresh produce. They also soon became fine bakers of French bread and pastries. Even today, most of the top local bakeries bear Swiss and German names.
The lack of women, medical personnel, and teachers in La Nouvelle Orléans prompted Bienville to write home asking that members of the order of Ursuline Sisters, the nuns he had seen at work in Canada, come to assist him in Louisiana. The first Ursulines arrived on August 6, 1727, and they immediately became indispensable members of the colony. They provided a home for the upstanding, middle-class filles de cassette or “casket girls” (so-called because of the government issued chests with clothing and linen that each brought), who were sent over regularly from 1728 to 1751 to become wives for the colonists. The Ursulines took care of orphans, conducted a free school, operated a hospital, and instructed the slaves for baptism.
It was these nuns, the daughters of French aristocratic and middle-class families, who brought with them knowledge of the latest French culinary fashions. One of the Ursulines, Sister Xavier Hébert, was the first woman pharmacist in the New World. A condition of the agreement between the Compagnie des Indes and the Ursulines in 1726 was that the sisters would plant an herb garden in Louisiana and teach its benefits. A bay leaf added to stews and soups prevented souring, and it also kept weevils out of the flour; dill was used to encourage soothing sleep, oregano to reduce swelling, parsley to remove the smell of garlic, shallots for strength, and sage “to put fever to flight.”
If the nuns brought with them the rudiments of French cuisine, blacks can be credited with using what little was available locally to devise something edible. By 1744, the Compagnie des Indes had imported some two thousand slaves from the west coast of Africa and the West Indies. The 1724 Code Noir, French regulations for treatment of blacks, made Louisiana a pleasanter place for them to live than British ruled areas. In addition, the French were lax in enforcing regulations against miscegenation.
African American cooks had a sophisticated tradition of preparing food. Their African ancestors had traded with Arabs since the eighth century and had left a legacy of various cultivated Middle Eastern vegetables. By the sixteenth century, West African farmers were growing corn, peanuts, yams, eggplant, garlic, and onions, which they had assimilated into their native diet of kidney beans, varieties of rice, green leafy vegetables, and okra. Foods were prepared by long, slow cooking and were served with delicate sauces.
It is thought that slaves brought okra, called ‘kingombo’, to the New World. The popular mainstay among Catholic families of Louisiana, gumbo ‘z’herbes’ is taken from a similar African dish made of various greens and herbs. An old saying states that a new friend will be made for each different green used in the soup. During the months when okra was in season, it was the key ingredient for thickening gumbo, replacing the Indian filé powder used the rest of the year.
In New Orleans, as in France, having a good cook was crucial to one’s social status, and, as in France, the proper Creole ‘lady’ did not venture too far from the kitchen while the meal was being prepared. Male and female slave cooks enjoyed such an elevated social position that they were taught to read and write in order to make use of French recipes. “The preparation of food is as much an art form to my people as music,” says Leah Chase, noted chef of Dooky Chase’s restaurant in the central city area, the black counterpart of Antoine’s. “There isn’t one famous Creole dish that didn’t pass through the hands of a black chef or cook before it came to be written down.”
African American cooks are credited with taking the French peasant’s thickener, roux (from the French roux beurre, which means “reddish-brown butter”), as a base for sauces, stews, or soups. Especially in Creole and Cajun dishes, which traditionally are slow-cooked in a single large pot, the thickener is a key element. Among local cooks today, roux made by a master is considered an even better gift than chocolates.
By 1743, when the Marquis de Vaudreuil-Cavagnal, known as the Grand Marquis, arrived as the governor, New Orleans had developed its own elegant Creole society. By all accounts, the governor and his entourage of officials led a life as close to that of the Court of Versailles as could be mustered. They brought their own chefs from France and kept the prominent locals awestruck with their elaborate feasts.
Perhaps Creole cuisine would have become just a slightly distressed reproduction of eighteenth-century French cuisine had not the Spanish come. In November 1762, Louis XV of France secretly gave Louisiana to his Spanish cousin Charles III in an effort to keep it safely out of the hands of the British after the French defeat in the Seven Years’ War. The Spanish introduced to the Louisiana diet the culinary tricks that they had learned from the Mayans, Aztecs, and Incas. Even the term Créole comes from the Spanish word criollo, originally denoting a person of European or African descent born outside those countries.
It was during the Spanish period in Louisiana that the first Acadians came to settle in the area. They descended from families that had left France in the early 150Os and settled in Nova Scotia. In 1755 the British demanded they pledge allegiance to England or be expelled from Canada. When they refused, they were deported, some being sent to the American colonies and many to France. When those in France who were destitute were offered a home in French-speaking Louisiana by the Spanish, many accepted, and by 1763, they had begun to found settlements deep in the swamps and bayous around New Orleans. They quickly adapted to the rough life and happily lived off the bountiful fresh foods that the wetlands provided. Today the Acadians in Louisiana, now called Cajuns, number perhaps three-quarters of a million and many still speak a French somewhat akin to that of the seventeenth century.
The Spanish were familiar with many of the New World’s foods long before they arrived in Louisiana. In the fifteenth century, Columbus had brought yams, tobacco, kidney beans, maize, and red pepper back to Southern Europe and North Africa. Later the Spanish explorers brought back the tomato (known as “wolf peach,” “apple of the moors,” and “love apple”) from Mexico. The Italians and Spanish adored it: the French and English thought it was poisonous. As a matter of fact, the French did not begin to use it until 1850, when the Empress Eugénie introduced it at Napoleon’s table.
The Spaniards brought their love for peppers and the tomato back with them to Louisiana, and they began the practice of adding green pepper to sauces and meat dishes, which would arrest the growth of bacteria, reducing the spoilage that was a constant problem in those days before refrigeration. When coupled with the roux, the tomato became the integral ingredient in shrimp Creole sauce; in the rich gravy for grillades; and in the base for court bouillon, a thick seafood stew similar to bouillabaisse. The Spanish paella, a rice and shellfish dish, became the forerunner of Creole jambalaya.
After the Civil War, the impoverished Creoles were said to be “too poor to paint and too proud to whitewash.”
The early Creole proverb ‘Misé fe macaque mangé piment’ (“Misery makes the monkey eat red pepper”) perhaps suggests why hot peppers were such an important ingredient in this region of the country. The Cajuns were economically, culturally, and geographically cut off from the more cosmopolitan areas. As Joel Cavaness, an accomplished Cajun cook and a direct descendant of the original Acadians, explains: “We grew up in the bayou eating only what we could grow, catch or shoot and cook in one big pot. We ate what was in season, which could mean that we ate crawfish daily for weeks. The great variety and spice in our diet came from combining various peppers from the garden with some onions, garlic and bell pepper to create bisque, étouffé, court bouillon, sauce piquante, jambalaya, gumbo, or just simple, well-seasoned, boiled crawfish, shrimp, and crabs.”
From the Spanish period onward, no matter how poor, each household could easily grow one or two varieties of hot peppers. The flavors of foods, from old raccoon meat to “mud bugs” (crawfish), were greatly enhanced by the addition of a little salt and a dose of red pepper. Eating pickled and raw pepper is still a popular south Louisiana barroom sport, a proof of manhood. If the Spanish influence was ever in danger of fading, the Mexican War reversed the trend. Hundreds of Louisianians went off to Mexico in the 184Os and returned home with a renewed passion for the pepper. One of these men brought the Mcllhenny family of Avery Island some special Mexican pepper seeds. The result was Tabasco sauce, which now sells more than seventy million bottles annually.
Political turmoil throughout the world played an important part in refining the culinary style of the Creoles. Aristocrats fleeing the French Revolution brought a renewed dose of haute cuisine. Those from the West Indies and Santo Domingo brought with them techniques for the preparation of fish with a Spanish flavor. In the late nineteenth century, New Orleans also became a disembarkation point for Sicilians arriving in America, and they brought along their rich red gravies and dishes using garlic and breadcrumbs, such as stuffed artichokes and eggplant, which, in Louisiana, became the stuffed Indian mirliton. Yugoslavs from the Dalmatian coast were working the local oyster beds as early as 1840. Their expertise was so great that, by 1858, the local business directory had to give five pages over to oyster bars, oyster houses, and restaurants specializing in oyster dishes.
Even Asians played a part in the diet of Louisiana. Despite the hackneyed barb comparing Creoles and Chinese—“They both worship their ancestors and eat a lot of rice”—it was Lee Yuen, a rice farmer from Canton, who perfected the method for drying shrimp in Louisiana in 1867. The new process made it possible to have shrimp year round.
Between 1800 and 1860, Creole society flourished, and Creole cuisine, as it is known today, became firmly established. By 1840 New Orleans was the fourth largest city in the United States, the second largest port, and an economic center that attracted executives from all over the world. It was one of the first cities in the country to have public restaurants, and its hotel dining rooms served continental and Creole cuisine.
Creole cooking might have gone full circle and become just another outgrowth of the aristocratic gastronomy of Europe had not the Civil War come along and changed the household economy of the Creoles. Suddenly the French-speaking Creoles had to take a backseat to the influx of Americans and the Reconstruction government. The Creoles became the “red beans-and-rice aristocracy,” people who were said to be “too poor to paint and too proud to whitewash.” However, the Creoles still loved to eat and entertain. When they could not afford fine meats, they would make a tasty gumbo from fresh vegetables and a little leftover chicken or seafood. When coffee became expensive, the refugees of the Napoleonic era in France taught them to roast the root of the Belgian endive (chicory) to stretch their supply. When the price of ice exceeded their means, they would crush glass and sew it into cheesecloth bags that were then floated in pitchers of water to give the tinkle of ice.
This tradition and pride have fostered and preserved Creole cuisine. Strangely, tourism, which rejuvenated the city’s economy in the 1950s, 1960s, and early 1970s, came close to destroying the flavors that were innately Creole. Local restaurants were forced to create an Americanized version of the local cuisine that would be more palatable to tourists. Chicory was taken out of the coffee, filé and cooked-down murky morsels of crab and oyster eliminated from the gumbo, and red pepper removed from everything and replaced with freshly ground black pepper. Authenticity in preparation went by the wayside with such shortcuts as red sauces made with canned tomato paste. Visitors were served a brunch of eggs Benedict rather than grillades and grits.
In those years, Creole cuisine remained alive only in the city’s homes and its many neighborhood and family restaurants. Nouvelle cuisine and cuisine minceur came and went without making so much as a ripple on the roux-based sauces of the Creoles.
By the 1980s, food writers were ready for something new, and suddenly Creole and Cajun cuisine was pulled out of the culinary closet—ethnic, inexpensive, relatively easy to prepare, and totally different from the elegant culinary style of the past decade. After more than two hundred years, Creole food has finally achieved its culinary respectability. | textbooks/workforce/Food_Production_Service_and_Culinary_Arts/Culinary_Foundations_(Cheramie_and_Thibodeaux)/06%3A_Cajun_Creole_Cuisine_and_Roux/6.01%3A_A_True_and_Delectable_History_of_Creole_Cooking.txt |
Roux is a base sauce in international cuisines, originally French, composed of varying ratios of flour and fat (usually butter), useful for making sauces, and for thickening soups or gravies. The benefits of using a roux include the following: It does not have to cook very long to remove a floury taste, clumps of flour are removed, and it creates unique flavors. It can be cooked to different degrees:
• White roux
• Blonde roux
• Brown roux
• Dark Brown roux
Uses
Depending upon the intended use, and a darker roux (one that has been cooked longer) will also be thicker and have more flavor, but will have less thickening power.
The fat is most often butter in French cuisine, but may be lard or vegetable oil in other cuisines. The roux is used in three of the five mother sauces of classical French cooking: béchamel sauce, velouté sauce, and espagnole sauce.
In Cajun cuisine, roux is made with bacon fat or oil instead of butter and cooked to a medium or dark brown color, which lends much richness of flavor, but makes it thinner.
Central European cuisine often uses lard (in its rendered form) or more recently vegetable oil instead of butter for the preparation of roux, which is called:
• ‘zápražka’ in Slovak,
• Jíška’ in Czech,
• zasmażka’ in Polish,
• ‘zaprška’ (запршка) in Bosnian, Croatian, Serbian, and Macedonian,
• ‘zaprazhka’ (запръжка) in Bulgarian,
• ‘rántás’ in Hungarian and
• ‘Mehlschwitze’ in German.
• Japanese curry, or karē, is made from a roux made by frying yellow curry powder, butter or oil, and flour together.
• Roux (meyane) has been used in Ottoman and Turkish cuisine since at least the 15th century.
Methods
1. A basic roux may be composed of equal parts flour and butter by weight.
2. The fat is heated in a pot or pan, melting it if necessary.
3. Then the flour is added.
4. The mixture is heated and stirred until the flour is incorporated.
5. It is then cooked until at least the point where a raw flour taste is no longer apparent and the desired color is achieved.
The final color can range from nearly white to nearly black, depending on the length of time it is heated and its intended use. The end-result is a thickening and flavoring agent.
Roux is most often made with butter as the fat base, but it may be made with any edible fat. For meat gravies, fat rendered from meat is often used. In regional American cuisine, bacon is sometimes rendered to produce fat to use in the roux. If clarified butter is not available, vegetable oil is often used when producing dark roux, since it does not burn at high temperatures, as whole butter would.
Alternatives
Cooks can substitute for roux by adding a mixture of cold water and wheat flour to a dish that needs thickening, since the heat of boiling water will release the starch from the flour; however, this temperature is not high enough to eliminate the floury taste. A mixture of water and flour used in this way is colloquially known as “cowboy roux”, and in modern cuisine, it is called a white wash. It is used infrequently in restaurant cooking, since it imparts a flavor to the finished dish that a traditional haute cuisine chef would consider unacceptable. Corn flour (known as cornstarch in the United States) can be used instead of wheat flour. Since less is needed to thicken, it imparts less of the raw flour taste, and it also makes the final sauce shinier.
As an alternative to roux, which is high in fat and very energy-dense, some Creole chefs have experimented with toasting the flour without oil in a hot pan to use as an addition to gumbo. Cornstarch mixed with water (slurry), arrowroot, and other agents can be used in place of roux as well. These items do not contribute to the flavor of a dish, and are used solely for thickening liquids. More recently, many chefs have turned to a group of naturally occurring chemicals known as hydrocolloids. In addition to being flavorless and possessing the ability to act as a thickening agent. The resulting texture is thought by some to be superior, and only a small amount is required for the desired effect.
Notes, Tips and Variations
• Depending upon how you plan to use your roux, you may need to add the sauce's other ingredients before the roux is fully cooked.
• One way to use a roux is to add liquid to it, stirring it in as you go. Do not go the other way, adding the roux to the liquid, as you will get lumps. Once enough liquid has been added to the roux (you will know), you can safely add it back into another liquid.
• A good roux will have a slight shine to it, and neither the texture nor the taste of the flour will be apparent.
• When making a dark roux, switching from butter to an oil with a high smoke point (such as soybean oil or Canola oil) will allow for a higher cooking temperature, decreasing cooking time. Keep in mind that different fats will give the roux a somewhat different taste.
Escoffier on Roux
(Auguste Escoffier (1907), Le Guide Culinaire)
White Roux (Roux blanc)
Same quantities as for brown or pale roux, but the time of cooking is limited to a few minutes, as it is only needed, in this case, to do away with the disagreeable taste of flour that is typical of those sauces whose roux has not been sufficiently cooked.
Pale Roux (Roux blond)
The quantities are the same as for brown roux, but cooking must cease as soon as the color of the roux begins to change, and before the appearance of any coloring whatsoever. The observations I made relative to brown roux, concerning the thickening element, apply also to pale roux.
Brown Roux (Roux brun)
Quantities for making about one pound:
• 8 oz. by volume clarified butter
• 8 oz. by weight flour
Preparation.—Mix the flour and butter in a very thick saucepan, and put it on the side of the fire or in a moderate oven. Stir the mixture repeatedly so that the heat may be evenly distributed throughout. Brown roux is known to be cooked when it has acquired a fine, light brown color and when it exudes an odor resembling that of the hazelnut, characteristic of baked flour.
It is very important that brown roux should not be cooked too rapidly. When cooking takes place with a very high heat in the beginning, the starch is burned within its shriveled cells. The binding principle is thus destroyed and double or triple the quantity of roux becomes necessary in order to obtain the required consistency. However, this excess of roux in the sauce chokes it up without binding it, and prevents it from clearing. At the same time, the cellulose and the burnt starch lend a bitterness to the sauce of which no subsequent treatment can rid it. | textbooks/workforce/Food_Production_Service_and_Culinary_Arts/Culinary_Foundations_(Cheramie_and_Thibodeaux)/06%3A_Cajun_Creole_Cuisine_and_Roux/6.02%3A_Roux.txt |
Thumbnail: Poached egg on low carb bread. (Unsplash License; Seriously Low Carb via Unsplash)
07: The Menu and Poaching
The Menu is a list, in specific order, of the dishes to be served at a given meal. The Menu is central to the food service concept—it defines the product offering, establishes key elements of financial viability namely price and contribution margin, and provides a powerful marketing tool. It dictates staff, equipment, food, and décor choices. It is the most important document in the building!
The word ‘menu’ dates back to 1718, but the custom of making such a list is much older. It is said that in the year 1541 Duke Henry of Brunswick was seen referring to a long slip of paper. On being asked what he was looking at he said it was a form of program of dishes and by referring to it he could see what dish was coming and reserve his appetite accordingly. It is believed that perhaps it was this idea that led to development of menu cards.
During olden times ‘bill of fare’ of ceremonial meals were displayed on the walls to enable the kitchen staff to follow the order in which the meal had to be served. Modern menus did not appear until the nineteenth century when the Parisian restaurant Palais Royale provided customers with small, handy reproduction of the menu displayed on the door. Mid-nineteenth century saw the placement of menus at the end of the table from where the guests could choose the menu item that they wished to have. However, as time progressed, individualized menus came into being.
The menu is the most significant factor in a food service operation. A menu epitomizes a caterer’s F&B intention. People eat away from home for various reasons. However, to many, the food that they eat has the greatest and the most significant impact upon their experience. Therefore, the menu, which proclaims to the guests the choice of food items available, is a major factor in popularizing a restaurant and promoting F&B sales.
Badly composed menu is likely to spoil the best of dinners. Menu plays a competitive role in the commercial industry. Its effect is not only observed in satisfying a client, but also in generating sufficient revenue for the business. Firms should understand the role of menu and entail steps to better it if required.
Functions of the Menu
A menu performs the following functions:
1. Information: It satisfies a guest’s need for information about what food is available, how it is cooked and presented, and at what price.
2. Order: It presents the dishes in a logical order, usually listing the menu items under course headings, thereby making comprehension of the menu easy.
3. Choice: It determines the freedom of choice that a guest may have.
4. Image: Menu helps present the overall image and style of the restaurant.
5. Sales: It is a means of promoting sales by appropriately describing the dishes, which appeal to the guest.
In order for the menu to perform all these functions successfully, it must be informative, accurate, understandable, and well designed. A restaurant manager must ensure that the items mentioned on the menu are available at all times and as per description since it is frustrating for a guest to make a decision only to be told that the dish is not available or to receive a dish that is not as stated.
Menus are broadly classified into three styles as follows:
1. A la carte: It is a list of all dishes on offer, which is within the resources of a particular kitchen. It means ‘from the card’. From it, a guest may select items to compose his/her own menu. The charge of meal will be the total of the prices of individual dishes served to the guest. This is where the skill of the steward will come into picture, where he/she would do the suggestive selling and let the guests mix their choices in such a way that they enjoy the meal.
2. Semi a la carte: Some items are priced and ordered separately and some are priced to include other items.
3. Table d’ hote: It literally means ‘from the host’s table’. It is a meal usually divided into various courses with little or no choice, and is available at a fixed price.
Menus Also Classify by type:
Static Menu – All patrons are offered the same foods every day.
Cycle Menu – Developed for a set period. At the end of the period, the cycle repeats.
Market Menu – Based on the products available in the market. Also called “Seasonal” menu.
Hybrid Menu – Combines the static, the cycle and the market menus.
The Classical French 12 Course Menu
1. Hors d’oeuvre: This course is usually aimed to simulate appetite and, therefore, is composed of tangy and salty dishes. For example, potato salad, Caesar salad, Russian salad, caviar, smoked salmon, smoked ham, oyster, etc. all in small bite-sized servings and elegantly presented.
2. Potage: It refers to soups of two types—clear (consommé) and thick (cream, velouté, or puree). A clear soup on the menu card is generally listed first.
3. Poisson (fish): In this course normally poached/steamed/baked fish is served with an appropriate sauce and properly cooked vegetables.
4. Farinaceous: Dishes such as risotto, spaghetti, gnocchi, and penne may be served in place of the fish course. Egg dishes, such as en cocotte, sur le plat, may be served in this course, especially during a luncheon menu. They are seldom included during dinner.
5. Entrée: This is the first of the meat course at dinner; and it is usually complete in itself. For example, sweet breads, vol-au-vent, tournedos, etc.
6. Remove/Relevee: It is a large joint of meat. For example, leg of lamb, beef roast loin of pork, etc. Served with potatoes such as Dauphinoise, Puree, Duchesse, Gratinee etc.
7. Sorbet: Sometimes called the “Intermezzo”. This course is intended to be a pause during a long meal. A sorbet is supposed to settle dishes already served and to stimulate the appetite for the ones to follow. It is water ice flavored with champagne or any liquor or delicate wine. It is usually served in a champagne saucer with a teaspoon. Russian cigarettes may be passed around the table and ten minutes are allowed before the next course.
8. Roti: This course consists of roast poultry or game, such as chicken, duck, turkey, pheasant, partridge, etc., served with their sauces and gravy. A dressed salad is served along.
9. Legume (vegetable): The French customarily served vegetables as a separate course, for example, asparagus served with hollandaise sauce.
10. Entremets: This may consist of a hot sweet dish such as soufflé, rum omelet, etc. Petit fours are served with this course.
11. Savory: A savory course consists of a titbit on a hot canapé of a toast or fried bread. Cheese platter may also be presented with crackers, watercress, walnuts, and so forth. as accompaniments.
12. Dessert: This finale consists of a basket of fresh fruits sometimes placed on the table as a part of the decoration, along with nuts and simple fruit tarts. Different types of coffees are served with this course.
The Modern Seven-Course Menu
1. Amusee’: An elegant savory, hot or cold, two or three-bite course. It should stimulate the appetite and amuse the mouth, thus the name.
2. Potage: A soup; bisque, consommé, purée or chowder.
3. Poisson: The fish course, whole or filleted, served with properly cooked vegetables.
4. Intermezzo: Sorbet; a citrus or fresh fruit ice, not too sweet. Should be designed to cleanse the palate.
5. Entrée: The meat course; comprised of the portion of meat or poultry along with a starch such as potato or rice or pastry, perhaps a slice of Beef Wellington with Sauce Bordelaise.
6. Dessert: The sweet course; perhaps a custard, a pastry, a pudding, a mousse,, etc.
7. Salade/Cheese: Perhaps leaves of endive or heart of romaine with tiny tomatoes and vinaigrette. Alternatively, this could be a cheese course or a combination of both.
Coffee to conclude or perhaps a ruby or tawny port wine with the cheese.
Menu Sample, musthavemenus.com | textbooks/workforce/Food_Production_Service_and_Culinary_Arts/Culinary_Foundations_(Cheramie_and_Thibodeaux)/07%3A_The_Menu_and_Poaching/7.01%3A_The_Menu.txt |
Poaching is a Moist Heat Cooking Method
Have you ever poached an egg to make Eggs Benedict? Poached pears in wine for dessert? Delicately cooked a fish covered with water, stock or wine (poaching liquids) in a covered pan to preserve the moistness of the meat? These are examples of poaching you are probably familiar with.
It is the method accomplished with the least amount of heat, and, therefore is a gradual, gentle cooking process. Poaching is best for very delicate foods, such as eggs, fish, white meat chicken and fruit. It is a very healthy cooking method, because liquid—not fat—carries the heat into the food.
Poaching is ideally done at temperatures between 160°F and 190°F, or well below a simmer. The best way to tell if a poaching liquid is at the correct temperature is with an instant read thermometer. Short of that, look at the liquid in the pan. There should be a slight convective current in the liquid, as the warmer liquid rises to the surface. The liquid should be gently moving, but it should not be bubbling at all.
Poaching is Patience
Poaching takes patience. Poaching allows the proteins in foods to uncoil, or denature, slowly, without squeezing out moisture. If you were to drop a delicate chicken breast into boiling water, the proteins would seize up so quickly that all the moisture would be squeezed out, and you would end up with a small piece of dry rubber!
Poaching Liquids
You can poach in water, milk or a flavorful broth. The broth used in poaching is called a court bouillon. It consists of the poaching liquid itself (often broth or stock) an acid (wine, lemon juice, or vinegar), a bouquet garni (a small bundle of aromatics tied up in cheesecloth, or just tied together with kitchen string (bay leaf, parsley, peppercorns, garlic, thyme, etc) and mirepoix (onion, celery and carrot. Traditional proportions for a white mirepoix is two parts onion to one part each celery and carrot). You can also poach in fats such as clarified butter, duck fat or olive oil. A raw, shelled, lobster tail poached in clarified butter or olive oil is a thing to behold.
For dessert preparations, fruit is often poached in sweet wine and water with some spices (star anise, clove, cinnamon, and so forth). Eggs are generally poached in water with a bit of vinegar. The acid in the poaching liquid helps to speed up the protein coagulation on the outside of the food. This helps hold delicate foods together during the poaching process (think eggs).
To poach a chicken breast: Bring 2 inches of poaching liquid to just below a simmer. You will know when you get there when there are lots of little bubbles all over the bottom of the pan, but no bubbles have started to rise to the top.
Place the chicken breast into the liquid. Keep an eye on the heat. If it starts bubbling, turn it down. If you do not see any convective currents, turn the heat up a little. Do not worry if the chicken breast is not completely submerged. You can use some tongs to turn it over. If totally submerged and you used an ovenproof pan, you may want to insure constant, all around heat by placing pan in a 325-degree oven.
Continue poaching until the internal temperature of the chicken breast has reached 160 degrees, F. Many books talk to you about pushing on the chicken or even cutting into it to see if it’s done. The most accurate method, though, is using an accurate instant read thermometer.
Take the piece of chicken out of the poaching liquid. It will be very pale in color. In a moist heat environment and at such low temperatures, there is no browning. You will also lose the deep flavor that some browning imparts. What you lose in flavor though is made up for in moisture.
Poaching is a wonderful way to keep delicate foods moist and plump. Then, there is the added advantage of turning the poaching liquid into a sauce by reducing a part of the poaching liquid, thicken with beurre manie, or monte au beurre or adding a spot of cream. A small amount of rich sauce can greatly enhance the dish.
As you can see from the above procedure, no special equipment is needed for poaching. A sauté pan or even just a saucepan will suffice. As long as your pan can hold two or three inches of liquid, you are good to go. They do sell a special pan for poaching whole fish and I am sure you can poach just about anything in it that fits.
How to Poach an Egg
Many a cook has been frustrated by the seemingly simple and straightforward task of poaching an egg. Most egg poaching disasters can be averted by keeping the water below a simmer.
1. Bring 3 inches of water and a splash of vinegar to about 170 degrees, F. Look carefully at the bottom of the pan. There should be small bubbles all over it, but they should not be rising to the top and breaking.
2. Crack an egg into a small cup.
3. Stir the water in a circular motion to get the water moving. Lower the egg into the water in the center of the pan. Tip the cup to let the egg slide out gently.
4. If any errant strings of white try to swirl away from the egg, gently push them back with a heat-resistant spatula or a spoon.
5. Let the egg gently poach for about 4-5 minutes, depending on how done you like your eggs. “Jiggle” the egg with your spoon. The white should be fairly firm, but the yolk should still shimmy. Remove the egg with a slotted spoon, and let it drain on some paper towels, or place in ice water for later service. Just bring water to poaching temperature and warm the egg for 40 seconds.
6. Serve on buttered toast, or get fancy and make Eggs Benedict. A lovely way to serve a poached egg at dinner is to make a salad with an acidic dressing. Perch the warm poached egg atop the salad and break the yolk. The rich yolk will blend with and become part of the dressing. Wonderful! (Research “Salade Lyonaise”…a great salad to serve as dinner. Just add some good crusty bread and a good white wine! Yum!)
Poached egg over roasted asparagus. Foodandwine.com
Eggs Benedict. whatsforeats.com
Curry-Poached Chicken over Basmati. Bonappetit.com | textbooks/workforce/Food_Production_Service_and_Culinary_Arts/Culinary_Foundations_(Cheramie_and_Thibodeaux)/07%3A_The_Menu_and_Poaching/7.02%3A_The_Cooking_Techniques_-_Poaching.txt |
• 8.1: Frying Methods
Frying is a dry-heat cooking technique that has been used for centuries. Sautéing, stir-frying, pan-frying and deep-frying all operate on the same principles -- what differentiates them is how much fat is used in cooking. It can range from a very thin layer (sautéing and stir-frying), to maybe a half inch of oil (for pan-frying), to enough oil to fully submerge an entire piece of food (deep-frying).
Thumbnail: Frying Spring Rolls (Unplash license; Joshua Hoehne via unsplash)
08: Frying
Frying is a dry-heat cooking technique that has been used for centuries. Sautéing, stir-frying, pan-frying and deep-frying all operate on the same principles -- what differentiates them is how much fat is used in cooking. It can range from a very thin layer (sautéing and stir-frying), to maybe a half inch of oil (for pan-frying), to enough oil to fully submerge an entire piece of food (deep-frying).
The biggest benefit to frying is speed. Fat is much better at transferring heat than either air or water, so frying cooks considerably faster than baking or boiling. In addition, the fat imparts a crispy crust and a richness and depth of flavor that is, too many folks, irresistible. However, there is one major drawback to frying: health concerns that come from eating fatty foods.
Regardless of how healthy the food was before it went into the deep fryer, it is going to come out with five to 40 percent absorbed oil by weight. That is a major drawback for anyone who is watching his or her fat or calorie intake. For healthy people who do not need to worry as much, however, the occasional fried treat is not a problem. To better understand these often-defamed snacks and treats (and sometimes whole turkeys); let's dive into the science of how simple hot oil transforms everyday foods into sinful delights!
Fried foods are typically cooked in oil that has been heated to 350 to 425 degrees F. If you have ever seen food dropped into a hot fryer, then you know that it immediately starts sizzling and bubbling. It looks as if the oil itself is boiling, but those bubbles are actually caused by hot steam shooting out of the food. This sudden expulsion of steam is caused when water, which normally boils at 212 degrees F, hits oil that has been heated as much as twice that temperature. In fact, this vaporization occurs so rapidly and violently that, if you were able to watch it at a microscopic level, it would look like thousands of explosions all over the surface of the food! This mass exodus of steam is important for several reasons: (1) the water vapor repels the oil and keeps it from penetrating beyond the surface; (2) the steam cools the oil surrounding the food, which buys time for flavors to develop and heat to make its way to the center of the food without burning around the edges.
When Food Is Done Cooking
As more and more steam escapes from the food, its surface dehydrates, which leaves behind a crispy crust. Once most of the moisture is gone from the outer layer, heat is able to travel more quickly to the center of the food. Steam will continue to escape, but you will see fewer, less urgent bubbles. This is a signal that your food is almost done, and the crust is about to truly dry out and start crisping up. As soon your food reaches the golden-brown color you like, pull it out, drain, season and serve it! If deep frying chicken, utilize an instant-read thermometer to make sure chicken is properly cooked (165F).
Preventing Greasiness and Sogginess
Remember how I mentioned that the steam released from food cools the oil around it? If you are frying at home, you will always get some temperature loss after adding your food, but most recipes account for a normal drop in temperature.
For example, if a recipe tells you to heat your oil to 375 degrees F, it understands that once the food goes in, you will actually be cooking at 350F, and that's okay. If you overcrowd the pan, however, you may end up dropping the temperature far below what the recipe anticipated, and your food may come out unpleasantly greasy. That is why most recipes say things like "don't overcrowd the pan" or "cook in batches." Why does too-cool oil cause greasiness? Because of steam, or in this case, a lack thereof. When the oil is too cool, the explosions of steam you would normally get when adding food to hot oil are less extreme, or worse, nonexistent. Steam exits the food slower than it should and you lose the oil-repelling power of the steam jets. That is why most recipes tell you to preheat your oil before adding any food.
Good hot oil creates a situation akin to trying to cram your way down a flight of stairs in a subway/metro station just moments after a full train lets out at rush hour. You are the oil; the commuters are the steam, and you are not getting through until they stop coming.
Excessive greasiness can also be caused by poor drainage or by sitting for too long before serving. Ironically, batch frying, which is supposed to alleviate greasiness, can be the very reason fried foods have to sit too long before serving. Better than using a flat surface with paper towel to drain fried foods, using a wire rack inside a sheet pan will keep cooling fat away from the food. The solution once again is to keep that steam flowing! That usually means immediately transferring your food to a warm (200 degrees F) oven until you are ready to serve. Keeping your food steaming hot slows the oil's migration into your food while at the same time preventing another unpleasant end: sogginess.
Sogginess is a particularly common problem with fried foods that have been coated with a batter or breading. When food starts to cool, the moisture in the space between the crust and the food turns into water droplets instead of steam. This can make the crust soggy from the inside out and ruin your once crispy crust.
Batters and Breading
Fried foods are often dipped in batters or breadings before being cooked. The purpose of these coatings is to protect food from the violent surface reactions of frying, retain moisture and provide a pleasant flavor and texture.
Batters result in a smooth, crispy and often delicate crust. Items are sometimes dusted in flour before being battered. Batter recipes vary widely, so results differ depending on ingredients. For example, high gluten flours result in a chewy (some might say tough) crust, whereas gluten-free flours (like rice flour) result in a paper-thin ultra-crispy crust (think: Korean fried chicken).
Adding eggs or sugar to a batter will result in a darker crust, which may or may not be desirable. Batter coatings are smoother and have less surface area than most breaded coatings, so they tend to absorb less cooking oil. They also tend to offer the most protection for delicate foods, which is why fish are commonly battered before frying (think: fish and chips). Louisiana style fried fish is usually seasoned then dredged in corn flour or corn meal.
Breadings result in a crispy, crunchy, textured crust. Breaded coatings can range from fine breadcrumbs (think: Chick-fil-A), to large, extra-crispy breadings (think: KFC, Popeye's, Japanese tempura). Fine breadcrumbs tend to absorb less oil then the extra-crispy style, since they provide less surface area for oil to soak into, but they are prone to sogginess. Extra-crispy style breadings are usually achieved by incorporating large, already crispy particles, such as Panko-style breadcrumbs or cereal, such as cornflakes. Common breading procedure:
Flour (sometimes seasoned) >>>>>> Egg Wash, Buttermilk, Whipped egg whites >>>>>>> Corn Flour, White Flour, Panko, Cracker Crumbs
Although batters and breadings are delicious, some foods do not require a coating at all. Starchy foods, like potatoes, plantains and yucca root will form their own natural protective skin once they're dunked in the fryer. This makes prep easy and accessible for the home cook.
Pan-Fried Chicken. countryliving.com
Deep-Fat Fried Chicken. bonappetit.com | textbooks/workforce/Food_Production_Service_and_Culinary_Arts/Culinary_Foundations_(Cheramie_and_Thibodeaux)/08%3A_Frying/8.01%3A_Frying_Methods.txt |
• 9.1: About Flavors
The chef must understand how to flavor foods and be able to recognize flavoring ingredients and know how to use them. This chapter looks at the sense of taste and smell and the flavoring ingredients used in the professional kitchen to enhance foods. Flavorings are the herbs, spices, salt, oils, vinegars, condiments, wines and other alcoholic beverages typically used to create, enhance or alter the natural flavors of a dish-are featured.
• 9.2: Flavorings - Herbs and Spices
Herbs and spices are used as flavorings. Herbs refer to the large group of aromatic plants whose leaves, stems or flowers are used to acid flavors to other foods. Most herbs are available fresh or dried. Because drying alters their flavors and aromas, fresh herbs are generally preferred and should be used if possible. Spices are strongly flavored or aromatic portions of plants used as flavorings, condiments or aromatics.
• 9.3: Blends and Storage of herbs and spices
Many cuisines have created recognizable combinations of flavors that are found in a variety of dishes. Although many of these blends are available already prepared for convenience, most can be mixed by the chef as need. (And commercial blends can contain large amounts of salt.)
• 9.4: Salt, Oils, Condiments and Vinegars
Thumbnail: Common kitchen spices (Unsplash License; Calum Lewis via Unsplash)
09: Flavor and Taste
Flavor and Taste
A must have book for any serious chef is The Flavor Bible by Page and Dornenburg. A listing of different foods, spices and herbs along with the other foods, spices and herbs in which they pair well
walmart.com
Flavors
The chef must understand how to flavor foods and be able to recognize flavoring ingredients and know how to use them. This chapter looks at the sense of taste and smell and the flavoring ingredients used in the professional kitchen to enhance foods. Flavorings are the herbs, spices, salt, oils, vinegars, condiments, wines and other alcoholic beverages typically used to create, enhance or alter the natural flavors of a dish-are featured.
From the simplest grunt of pleasure upon biting into a chunk of meat fresh from the fire to the most sophisticated discourse on the fruity top notes of a full-bodied Cabernet Sauvignon, people have long attempted to describe the flavors of food. This is clone by describing physical perceptions ("it tastes tart or sugary" or "it feels greasy") or the recognition of the flavor ("I can sense the rosemary" or "there is a hint of strawberries"). In either case, the terms flavor and taste are often confused. Although often used interchangeably, they are not synonymous.
A flavor is a combination of the tastes, aromas and other sensations caused by the presence of a foreign substance in the mouth.
Tastes are the sensations we detect when a substance is exposed to the taste buds on the tongue (sweet, sour, salt, bitter and umami.) Some substances irritate other nerves on the tongue or embedded in the fleshy areas of the mouth. These nerves respond to sensations of pain, beat or cold, or sensations our brain interprets as spiciness, pungency, or astringency.
Mouthfeel refers to the sensation created in the mouth by a combination of a food's taste, smell, texture and temperature.
Aromas are the odors that enter the nose or float up through the back of the mouth to activate smell receptors in the nose. Whenever a particular taste, sensation and/or aroma is detected, a set of neurons in the brain is excited and, with experience, we learn to recognize these patterns as the flavor of bananas, chocolate , grilled lamb or sour milk. Each person has a unique ability to recognize and appreciate thousands of these patterns.
This collection of flavors and your ability to recognize them is sometimes referred to as your palate.
Tastes: Sweet, Sour, Salty, Bitter and now Umami
Over the centuries, various cultures have developed complex philosophies based, in part, on the basic tastes they found in the foods they ate. For example, ' as early as 1000 R.C.E., the Chinese were describing the five-taste scheme that they still adhere to today. For them, each of the basic tastes - sweet, sour, salty, bitter and pungent/ hot/spicy- is associated with a vital organ of the body, a certain season, a specific element of nature, or an astrological sign. Maintaining the proper balance of tastes in a dish or during a meal assists in the maintenance of good health and good fortune.
About the same time, in what is now India, the practice of ayurvedic medicine was developing. Indians recognized six tastes (and still do) sweet, sour, salty, spicy/ pungent, bitter and astringent. Based on the tastes of various herbs and spices, practitioners of ayurvedic medicine associate them with specific vital organs or bodily systems. India n cooks attempt to create dishes with a balance of all six tastes, in part to encourage good health.
A continent away and several hundred years later, the Greek philosopher Aristotle identified seven tastes. He arranged the various tastes on a sort of continuum with the two primary and contrasting tastes, sweet and bitter, at either end. He placed a secondary taste next to each primary taste: succulent to the right of sweet and salty to the left of bitter. Between these secondary tastes he placed - from left to right- pungent, harsh and astringent. Each taste gave way to the next, creating, along with the other senses, the perception of flavors.
As the understanding of the human body evolved, the definition of taste came to be based more on science than on a balancing of elements. Today, taste is defined as the sensations detected when substances come in contact with the taste buds on the tongue.
Sweet - For most people, sweetness is the most pleasurable and often sought-after taste, although, ironically, the fewer sweet-tasting foods we consume, the more enhanced our ability to recognize sweetness becomes. A food's sweetness comes from the naturally occurring sugars it contains (for example, sucrose and fructose) or sweeteners added to it. This sweetness can sometimes be enhanced by adding a small amount of a sour, bitter or salty taste. Adding too much sourness, bitterness or saltiness, however, will lessen our perception of the food's sweetness.
Sour - Considered the opposite of sweet, a sour taste is found in acidic foods and, like sweetness, can vary greatly in intensity. Many foods with a dominant sour taste, such as reel currants or sour cream, will also contain a secondary or slight sweetness. Often a sour taste can be improved by adding a little sweetness or negated by adding a large amount of a sweet ingredient.
Salty - With the notable exception of oysters and other shellfish and seaweed, the presence of a salty taste in a food is the result of the cook's decision to acid the mineral sodium chloride, known as salt, or to use a previously salted ingredient such as salt-cured fish or soy sauce. Salt helps finish a dish, heightening or enhancing its other flavors. Dishes that lack salt often taste flat. Like the taste of sweetness, the less salt consumed on a regular bas is, the more saltiness we can detect in foods.
Bitter - Although the bitterness associated with tasting alkaloids and other organic substances may occasionally be appreciated, such as when tasting chocolate or coffee, a bitter-flavored ingredient unbalanced by something sour or salty is gene rally disliked and, as a survival mechanism, is believed to serve as a warning of inedibility or unhealthfulness.
In the past several years, many western researchers have begun to recognize a fifth taste, akin to the savory taste long recognized as the fifth taste in Japanese savory a food that is not sweet cuisine. Called ‘um ami ‘(from the Japanese word umai, meaning "delicious"), this fifth taste does not have a simple English translation. Rather, for some people it refers to a food's savory characteristic; for others to the richness or fullness of a dish's overall taste, and still others, the meatiness or meaty taste of a dish.
Taste buds sense umami in the presence of several substances, including the naturally occurring amino acid glutamate and its commercially produced counterpart known as monosodium glutamate (MSG).
Cheeses, meats, rich stocks, soy sauce, shellfish, fatty fish, mushrooms, tomatoes and wine are all high in glutamate and produce the taste sensation of umami. Aged or fermented foods also provide umami.
Often food professionals and others refer to tastes in addition to sweet, sour, salty, bitter and umami. Typically, they describe something as pungent, hot, spicy or piquant or something that is astringent, sharp or dry. None of these terms, however, fit the definition of a taste, as none are detected solely by taste buds. Rather, these sensations are detected by nerve endings embedded in the fleshy part of the mouth. These nerves, when "irritated" by the presence of compounds such as piperine (the active ingredient in black peppercorns) or capsaicin (the active ingredient in chiles), register a burning sensation that the brain translates as the hot and spicy "taste" of Szechuan or Mexican cuisines, for example.
Factors Affecting Perceptions of Flavors
Obviously, the most important factors affecting the flavor of a dish are the quantity, quality and concentration of the flavoring ingredients. (With practice, a chef gains a feel for the proper proportions.) Other factors that affect one's perception of flavors include the following:
Temperature - Food sat warm temperatures offer the strongest tastes. Heating foods releases volatile flavor compounds, which intensifies one's perceptions of odors. This is why fine cheese is served at room temperature to improve its eating quality and flavor. Foods tend to lose their sour or sweet tastes both the colder and the hotter they become. Saltiness, however, is perceived differently at extreme cold temperatures; the same quantity of salt in a solution is perceived more strongly when very cold than when merely cool or warm. Therefore, it is best to adjust a dish's final flavors at its serving temperature.
That is, season hot food when they are hot and cold foods when they are cold.
Consistency - A food's consistency affects its flavor. Two items with the same amount of taste and smell compounds that differ in texture will differ in their perceived intensity and onset time; the thicker item will take longer to reach its peak intensity and will have a less intense flavor. For example, two batches of sweetened heavy cream made from the same ingredients in the same proportions can taste different if one is whipped and the other is un-whipped; the whipped cream has more volume and therefore a milder flavor.
Presence of contrasting tastes - Sweet and sour are considered opposites, and often the addition of one to a food dominated by the other will enhance the food's overall flavor. For example, adding a little sugar to vinaigrette reduces the dressing's sourness, or adding a squeeze of lemon to a broiled lobster reduces the shellfish's sweetness. Nevertheless, add too much, and the dominant taste will be negated. Likewise, adding something sweet, sour or salty to a dish with a predominantly bitter flavor will cut the bitterness.
Presence of fats - Many of the chemical compounds that create tastes and aromas are dissolved in the fats naturally occurring in foods or added to foods during cooking. As these compounds are slowly release d by evaporation or saliva, they provide a sustained taste sensation. If, however, there is too little fat, the flavor compounds may not be released efficiently, resulting in a dish with little sustained flavor. Too much fat poses another problem; it can coat the tongue and interfere with the ability of taste receptors to perceive flavor compounds.
Color - A food's color affects how the consumer will perceive the food's flavor before it is even tasted. When foods or beverages lack their customary color, they are less readily identified correctly than, when appropriately colored. As color level change s to match normal expectations, our perception of taste and flavor intensity increases. A miscue created by the perceived flavor (the flavor associated with the color) can have an adverse impact on the consumer's appreciation of the actual flavor. For example, if the predominant flavor of a dessert is lemon, the dessert or some component of the dessert should be yellow; a green color will trigger an expectation of lime and the possible disappointment of the consumer. Similarly, the dark ruby-red flesh of a blood orange looks different from the bright orange flesh of a Valencia orange. This tonal difference can create the expectation of a different, non-orangey flavor, even though the blood orange's flavor is similar to that of other sweet orange varieties. Likewise, a sliced apple that has turned brown may suggest an off-flavor, although there is none.
Compromises to the Perception of Taste
The sense of taste can be challenged by factors both within and beyond one's control. Age and general health can diminish one's perception of flavor, as can fatigue and stress. Chefs need to be aware of the age and health of their clientele, adjusting the seasoning of foods served according to their needs. Here are some factors that can affect one's taste perceptions.
Age. "The bad news is that taste and smell sensitivity does decline as we age. The good news is that it declines at a slower rate than our vision and hearing. The sense of smell tends to decline earlier than the sense of taste. There is a great deal of variance across individuals, w it h some showing declines earlier than others."
Health. "An acute condition, such as a cold, can result in a temporary loss of smell. The presence of mucus can prevent airflow, preventing the odor compounds from reaching the olfactory receptors. In contrast, the sense of taste would remain largely unaffected. Medications can also alter the perception of taste and smell. Some medications suppress the perceptions of saltiness, while others result in chronic perception of bitterness. Still other medications alter salivary flow, making it difficult to swallow dry foods. A further complication is the underlying conditions for taking medication. If an individual is taking high blood pressure medications, not only may the medication have a direct impact on perceived taste, but the same individual is likely to be on a sodiumrestricted diet."
Smoking. "Anecdotal reports from those who quit smoking strongly indicate that smoking diminishes odor sensitivity. This is further supported by evidence indicating that people who smoke generally are less sensitive to odors than those who do not. In contrast, evidence indicates that if one waits two hours after smoking, the sense of taste is unaltered. Inu11ecliately after smoking, however, taste sensitivity is lowered."
Describing Aromas and Flavors in Food
Food scientists and professional tasters make their living describing the smell and taste of foods. Many have attempted to standardize the language used to describe positive and negative aromas and flavors in foods such as beer, cheese, chocolate, coffee and fish. Frequently they employ flavor wheels or other charts to identify types of flavors and tastes found in foods.
Describing Food Using Flavor Profiles
A food's flavor profile describes its flavor from the moment the consumer gr the first whiff of its aroma until he or she swallows that last morsel. It is a convenient way to articulate and evaluate a dish's sensory characteristics as well as identify contrasting or complementing items that could be served with it.
A food's flavor profile consists of one or more of the following elements:
Top notes or high notes - the sharp, first flavors or aromas that come from citrus, herbs, spices and many condiments. These top notes provide instant impact and dissipate quickly.
Middle notes – the second wave of flavors and aromas. More subtle and more lingering than top notes , middle notes come from dairy products, poultry, some vegetables , fish and some meats.
Low notes or bass notes - the most dominant, lingering flavors. These flavors consist of the basic tastes (especially sweetness, sourness, saltiness and um ami) and come from foods such as anchovies, beans, chocolate, dried mushrooms, fish sauce, tomatoes, most meats (especially beef and game) and garlic. Or they can be created by smoking or caramelizing the food's sugars during grilling, broiling and other dry-heat cooking processes.
After taste or finish - the final flavor that remains in the mouth after swallowing; for example, the lingering bitterness of coffee or chocolate or the pungency of black pepper or a strong mustard.
Roundness - the unity of the dish's various flavors achieved through the judicious use of butter, cream, coconut milk, reduced stocks, salt, sugar and the like; these ingredients cause the other flavorings to linger without necessarily adding their own dominant taste or flavor.
Depth of flavor - whether the dish has a broad range of flavor notes, these expressions can be applied to any dish to describe its sensory characteristics. For example, a free-range chicken has a flavor profile with a top note of rosemary. Its middle notes are contributed by the chicken, and the low notes from the anchovies and garlic. There is an aftertaste of garlic and vinegar. The sauce adds roundness to the chicken, thus creating a dish with a fine depth of flavor. An experienced chef is able to taste and evaluate aversion of this dish, adjusting flavorings, ingredients and cooking technique as needed to maintain the balance of flavors in the original recipe.
Important Terms
• seasoning - an item added to enhance the natural flavors of a food without dramatically changing its taste; salt is the most common seasoning
• flavoring - an item that adds a new taste to a food and alters its natural flavors; flavorings include herbs, spices, vinegars and condiments; the terms seasoning and flavoring are often used interchangeably.
• herb - any of a large group of aromatic plants w hose leaves, stems or flowers are used as a flavoring; used either dried or fresh
• aromatic - a food added to enhance the natural aromas of another food ; aromatics include most flavorings, such as herbs an d spices , as well as some vegetables
• spice - any of a large group of aromatic plants whose bark, roots, seeds, buds or berries are used as a flavoring; usually used in dried form, either whole or ground
• condiment - traditionally, any item added to a dish for flavor, including herbs, spices and vinegars; now also refers to cooked or prepared flavorings such as prepared mustards, relishes, bottled sauces and pickles. | textbooks/workforce/Food_Production_Service_and_Culinary_Arts/Culinary_Foundations_(Cheramie_and_Thibodeaux)/09%3A_Flavor_and_Taste/9.01%3A_About_Flavors.txt |
Herbs and spices are used as flavorings. Herbs refer to the large group of aromatic plants whose leaves, stems or flowers are used to acid flavors to other foods. Most herbs are available fresh or dried. Because drying alters their flavors and aromas, fresh herbs are generally preferred and should be used if possible. Spices are strongly flavored or aromatic portions of plants used as flavorings, condiments or aromatics. Spices are the bark, roots, seeds, buds or berries of plants, most of which grow naturally only in tropical climates. Spices are usually used in their dried form, rarely fresh, and can usually be purchased whole or ground. Some plants- dill, for example- can be used as both an herb (its leaves) and a spice (its seeds).
Herbs
Basil
Basil is considered one of the great culinary herbs. It is available in a variety of "flavors" - cinnamon, garlic, lemon, eve n chocolate- but the most common is sweet basil. Sweet basil has light green, tender leaves and small white flowers. Its flavor is strong, warm and slightly peppery, with a hint of cloves. Basil is used in Mediterranean and some Southeast Asian cuisines and has a special affinity for garlic and tomatoes. When purchasing fresh basil, loo k for bright green leaves; avoid flower buds and wilted or rust-colored leaves. Dried sweet basil is readily available but has a decidedly weaker flavor.
Opal basil is named for its vivid purple color. It has a tougher, crinkled leaf and a medium strong flavor. Opal basil may be substituted for sweet basil in cooking, and its appearance makes it a distinctive garnish.
Bay Leaves
Bay, also known as sweet laurel, is a small tree from Asia that produces tough, glossy leaves with a sweet balsamic aroma and peppery flavor. Bay symbolized wisdom and glory in ancient Rome; the leaves were used to form crowns or "laurels" Bay leaves worn by emperors and victorious athletes. In cooking, dried bay leaves are often preferred over the more bitter fresh leaves. Essential in French cuisine, bay leaves are part of the traditional bouquet garni and court bouillon. Whole dried leaves are usually added to a dish at the start of cooking, then removed when sufficient flavor has been extracted the Middle East. Its lacy, fern-like leaves are similar to parsley and can be used as a garnish.
Chervil
Chervil is commonly used in French cuisine and is one of the traditional fines herbes. Chervil's flavor is delicate, similar to parsley but with the distinctive aroma of anise. It should not be heated for long periods.
Chives
Chives are perhaps the most delicate and sophisticated members of the onion family. Their hollow, thin grass-green stems grow in clump s and produce round, pale purple flowers, which are use d as a garnish. Chives may be purchased dried, quick-frozen or fresh. They have a mild onion flavor and bright green color. Chives complement eggs, poultry, potatoes, fish and shellfish. They should not be cooked for long, periods or at high temperatures. Chives make an excellent garnish when snipped with scissors or carefully chopped and sprinkled over finished soups or sauces.
Garlic chives, also known as Chinese chives, actually belong to another plant species. They have flat, solid (not hollow) stems and a mild garlic flavor. They may be used in place of regular chives if their garlic flavor is desired.
Cilantro
Cilantro is the green leafy portion of the plant that yields seeds known as coriander. The flavors of the two portions of this plant are very different and cannot be substituted for each other. Cilantro, also known as Chinese parsley, is sharp and tangy with a strong aroma and an almost citrus flavor. It is widely used in Asian, Mexican and South American cuisines, especially in salads and sauces. It should not be subjected to heat, and cilantro's flavor is completely destroyed by drying. Do not use yellow or discolored leaves or the tough stems. When used in excess, cilantro can impart a soapy taste to foods.
Curry leaves
Curry leaves are the distinctively flavored leaves of a small tree that grows wild in the Himalayan foothills, southern India and Sri Lanka. They look like small shiny bay leaves and have a strong curry-like fragrance and a citrus-curry flavor. Often added to a preparation whole, then removed before serving, they can also be minced or finely chopped for marinades and sauces. Choose fresh bright green leaves, if possible, or frozen leaves; dried leaves have virtually no flavor. Although used in making southern Indian and Thai dishes, curry leaves (also known as neem leaves) must not be confused with curry powder.
Dill
Dill, a member of the parsley family, has tiny, aromatic, yellow flowers and feathery, delicate blue-green leaves. The leaves taste like parsley, but sharper, with a touch of anise. Dill seeds are flat, oval and brown, with a bitter flavor similar to caraway. Both the seeds and the leaves of the dill plant are used in cooking.
Dill is commonly used in Scandinavian and central European cuisines, particularly with fish and potatoes, mushrooms, and other vegetables. Both leaves and seeds are used in pickling and sour dishes. Dill leaves are available fresh or dried but lose their aroma and flavor during cooking, so add them only after the dish is removed from the heat. Dill seeds are available whole or ground and are used in fish dishes, pickles and breads.
Epazote
Epazote, also known as wormseed or stinkweed, grows wild throughout the Americas. It has a strong aroma similar to kerosene and a wild flavor. Fresh epazote is used in salads and as a flavoring in Mexican and Southwestern cuisines. It is often cooked with beans to reduce their gaseousness. Dried epazote is brewed to make a beverage.
Lavender
Lavender is an evergreen with thin leaves and tall stems bearing spikes of tiny purple flowers. Although lavender is known primarily for its aroma, which is widely used in perfumes, soaps and cosmetics, the flowers are also used as a flavoring, particularly in Middle Eastern cuisines though other cuisines use it as well. These flowers have a sweet, lemony flavor and can be crystallized and used as a garnish. Lavender is also used in jams and preserves and to flavor teas and tisanes.
Lemongrass
Lemongrass, also known as citronella grass, is a tropical grass with the strong aroma and flavor of a lemon. It is similar to scallions in appearance but with a woody texture. Only the lower base and white leaf stalks are used. Available fresh or quick-frozen, lemongrass is widely used in Southeast Asian cuisines.
Lime leaves
Lime leaves from a species of thorny lime trees are used much like bay leaves to flavor soups and stews in Thai and other Asian cuisines. These small, dark green leaves have a bright citrus floral aroma. Fragrant lime leaves are available fresh in the United States now that these trees are cultivated domestically.
Lovage
Lovage has tall stalks and large dark green celery-like leaves. The leaves, stalks and seeds (which are commonly known as celery seeds) have a strong celery flavor. Also known as, ‘sea parsley’, the leaves and stalks are used in salads and stews and the seeds are used for flavoring.
Marjoram
Marjoram, also known as sweet marjoram, is a flowering herb native to the Mediterranean and used since ancient times. Its flavor is similar to thyme but sweeter; it also has a stronger aroma. Marjoram is now used in many European cuisines. Although it is available fresh, marjoram is one of the few herbs whose flavor increases when dried. Wild marjoram is more commonly known as oregano.
Mint
Mint a large family of herb, includes many species and flavors (even chocolate). Spearmint is the most common garden and commercial variety. It has soft, bright green leaves and a tart aroma and flavor. Mint does not blend well with other herbs, so its use is confined to specific dishes, usually fruits or fatty meats such as lamb. Mint has an affinity for chocolate. It can also be brewed into a beverage or used as a garnish.
Peppermint
Peppermint has thin, stiff, pointed leaves and a sharper menthol flavor and aroma. Fresh peppermint is used less often in cooking or as a garnish than spearmint, but peppermint oil is a common flavoring in sweets and candies.
Oregano
Oregano, also known as wild marjoram, is a pungent, peppery herb used in Mediterranean cuisines, particularly Greek and Italian, as well as in Mexican cuisine. It is a classic complement to tomatoes. Oregano's thin, woody stalks bear clumps of tiny, dark green leaves, which are available dried and crushed.
Parsley
Parsley is probably the best-known and most widely used herb in the world. It grows in almost all climates and is available in many varieties, all of which are rich in vitamins and minerals. The most common type in the United States and Northern Europe is curly parsley. It has small curly leaves and a bright green color. Its flavor is tangy and clean. Other cuisines use a variety sometimes known as Italian parsley, which has flat leaves, a darker color and coarser flavor. Curly parsley is a ubiquitous garnish; both types can be used in virtually any food except sweets. Parsley stalks have a stronger flavor than the leaves and are part of the standard bouquet garni. Chopped parsley forms the basis of any fine herb blend.
Rosemary
Rosemary is an evergreen bush that grows wild in warm, dry climates worldwide. It has stiff, needlelike leaves; some varieties bear pale blue flowers. It is highly aromatic, with a slight odor of camphor or pine. Rosemary is best used fresh. When dried, it loses flavor, and its leaves become very hard and unpleasant to chew. Whole rosemary stems may be added to a dish such as a stew and then removed when enough flavor has been imparted. They may also be added to a bouquet garni. Rosemary has a great affinity for roasted and grilled meats, especially lamb.
Sage
Sage was used as a medicine for centuries before it entered the kitchen as a culinary herb. Culinary sage has narrow, fuzzy, gray-green leaves and blue flowers. Its flavor is strong and balsamic, with notes of camphor. Sage is used in poultry dishes, with fatty meats or brewed as a beverage. Sage’s strong flavor does not blend well with other herbs. It dries well and is available in whole or chopped leaves or rubbed (coarsely ground).
Savory
Savory has been used since ancient times. Its leaves are small and narrow, and it has a sharp, bitter flavor, vaguely like thyme. It dries well and is used in bean dishes, sausages and fine herb blends. While the variety called summer savory is most common and popular, a variety called winter savory is also available.
Tarragon
Tarragon is another of the great culinary herbs, is native to Iberia. It is a bushy plant with long, narrow, dark green leaves and tiny gray flowers. Tarragon goes well with fish and tomatoes and is essential in many French dishes such as bearnaise sauce and fine herb blends. Its flavor is strong and diffuses quickly through foods. It is available dried, but drying may cause hay-like flavors to develop.
Thyme
Thyme has been popular since 3500 B.C.E., when Egyptians used it as a medicine and for embalming. Thyme is as mall, bushy plant with woody stems, tiny green-gray leaves and purple flowers. Its flavor is strong but refined, with notes of sage. Thyme dries well and complements virtually all types of meat, poultry, fish, shellfish and vegetables. It is often included in a bouquet garni or added to stocks.
Spices
Different cuisines and areas of the world utilize different spices, and spice combinations. See the chart below:
Aleppo pepper
Aleppo pepper (ah-LEHP-oh) is made from bright red chiles grown in Turkey and northern Syria. The sun-dried Aleppo chiles are seeded and crushed, then used as a condiment. It has a sharp, but sweet, fruity flavor, with only mild heat (15,000 Scoville units) Although a member of the capsicum family, Aleppo pepper is used more like ground peppercorns (piper nigrum) than a chile . Also known as Halaby pepper, it acids an authentic Mediterranean flavor and fragrance to foods.
Anise
Anise is native to the eastern Mediterranean is grown commercially in warm climates throughout India, North Africa and southern Europe. The tiny, gray-green egg-shaped seeds have a distinctively strong, sweet flavor, similar to licorice and fennel. When anise seeds turn brown, they are stale and should be discarded. Anise is used in pastries as well as fish, shellfish and vegetable dishes, and is commonly used in alcoholic beverages (for example, Pernod and ouzo). The green leaves of the anise plant are occasionally used fresh as an herb or in salads.
Star anise
Star anise, also known as Chinese anise, is the dried, star-shaped fruit of a Chinese magnolia tree. Although it is botanically unrelated, its flavor is similar to anise seeds but bitterer and pungent. It is an essential flavor in many Chinese dishes and one of the components of five-spice powder.
Annatto
Annatto seeds are the small, brick red triangular seeds of a shrub from South America and the Caribbean. Annatto seeds add a mild, peppery flavor to rice, fish and shellfish dishes and are crushed to make Mexican achiote paste. Because they impart a bright yellow-orange color to foods, annatto seeds are commonly used as a natural food coloring, especially in cheeses and margarine.
Asafetida
Asafetida is a pale brown resin made from the sap of a giant fennel-like plant native to India and Iran. Also known as devil's dung, it has a garlicky flavor and a strong unpleasant fetid aroma (the aroma is not transferred to food being flavored). Available powdered or in lump form, it is used- very sparingly as a flavoring in Indian and Middle Eastern cuisines.
Capers
Capers come from a small bush that grows wild throughout the Mediterranean basin. Its unopened flower buds have been pickled and used as a condiment for thousands of years. Fresh capers are not used, as the sharp, salty, sour flavor develops only after curing in strongly salted white vinegar. The finest capers are the smallest, known as nonpareils, which are produced in France's Provence region. Capers are used in a variety of sauces (tartare, remoulade) and are excellent with fish and game. Capers will keep for long periods if moistened by their origin al liquid. Do not acid or substitute vinegar, however, as this causes the capers to spoil.
Caraway
Caraway is perhaps the world's oldest spice. Its use has been traced to the Stone Age, and seeds have been found in ancient Egyptian tombs. The caraway plant grows wild in Europe and temperate regions of Asia. It produces a small, crescent-shaped brown seed with the peppery flavor of rye. Seeds may be purchased whole or ground. (The leaves have a mild, bland flavor and are rarely use d in cooking.) Caraway is a ‘European’ flavor, used extensively in German and Austrian dishes, particularly breads, meats and cabbage. It is also used in alcoholic beverages and cheeses.
Cardamom
Cardamom is one of the most expensive spices, second only to saffron in cost. Its seeds are encased in 1/4-inch- (6-millimeter) long light green or brown pods. Cardamom is highly aromatic. Its flavor, lemony with notes of camphor, is quite strong and is used in both sweet and savory dishes. Cardamom is widely used in Indian and Middle Eastern cuisines, where it is also used to flavor coffee. Scandinavians use cardamom to flavor breads and pastries. Ground cardamom loses its flavor rapidly and is easily adulterated, so it is best to purchase whole seeds and grind your own as needed.
Chiles
Chiles, including paprika, chile peppers, bell peppers and cayenne, are members of the capsicum plant family. Although cultivated for thousands of years in the West Indies and Americas, capsicum peppers were unknown in the Old World prior to Spanish explorations during the 15th century.
Capsicum
Capsicum peppers come in all shapes and sizes, with a wide range of flavors, from sweet to extremely hot. Some capsicums are used as a vegetable, while others are dried, ground and used as a spice.
Cayenne
Cayenne, sometimes simply labeled "red pepper," is ground from a blend of several particularly hot types of dried red chile peppers. Its flavor is extremely hot and pungent; it has a bright orange-red color and fine texture.
Paprika
Paprika, also known as Hungarian pepper, is a bright reel powder ground from specific varieties of red-ripened and dried chiles. Paprika's flavor ranges from sweet to pungent; its aroma is distinctive and strong. It is essential to many Spanish and eastern European dishes. Mild paprika is meant to be used in generous quantities and may be sprinkled on prepared foods as a garnish.
Plant Spice
Chile powders are made from a wide variety of dried chile peppers, ranging from sweet and mild to extremely hot and pungent. The finest pure chile powders come from dried chiles that are simply roasted, ground and sieved. Commercial chilli powder, an American invention, is actually a combination of spices- oregano, cumin, garlic and other flavorings- intended for use in Mexican dishes. Each brand is different and should be sampled before using.
Crushed chiles
Crushed chiles, also known as chile flakes, are blended from dried, coarsely crushed chiles. They are quite hot and are used in sauces and meat dishes.
Cinnamon
Cinnamon and its cousin cassia are among the oldest known spices: Cinnamon's use is recorded in China as early as 2500 B.C.E., and the Far East still produces most of these products. Both cinnamon and cassia come from the bark of small evergreen trees, peeled from branches in thin layers and dried in the sun. High-quality cinnamon should be pale brown and thin, rolled up like paper into sticks known as quills. Cassia is coarser and has a stronger, less subtle flavor than cinnamon. Consequently, it is cheaper than true cinnamon. Cinnamon is usually purchased ground because it is difficult to grind.
Cinnamon sticks are used when long cooking times allow for sufficient flavor to be extracted (for example in stews or curries). Cinnamon's flavor is most often associated with pastries and sweets, but it has a great Ground Cinnamon and affinity for lamb and spicy dishes. Labeling laws do Cinnamon Sticks not require that packages distinguish between cassia and cinnamon, so most of what is sold as cinnamon in the United States is actually cassia, blended for consistent flavor and aroma.
Cloves
Cloves are the unopened buds of evergreen trees that flourish in muggy tropical regions. When dried, whole cloves have hard, sharp prongs that can be used to push them into other foods, such as onions or fruit, in order to provide flavor. Cloves are extremely pungent, with a sweet, astringent aroma. A small amount provides a great deal of flavor. Cloves are used in desserts and meat dishes, preserves and liquors. They may be purchased whole or ground.
Coriander
Coriander seeds come from the cilantro plant. They are round and beige, with a distinctive sweet, spicy flavor and strong aroma. Unlike other plants in which the seeds and the leaves carry the same flavor and aroma, coriander and cilantro are very different. Coriander seeds are available whole or ground and are frequently used in Indian cuisine and pickling mixtures.
Cumin
Cumin is the seed of a small delicate plant of the parsley family that grows in North Africa and the Middle East. The small seeds are available whole or ground and look (but do not taste) like caraway seeds. Cumin has a strong earthy flavor and tends to dominate any dish in which it is included. It is used in Indian, Middle Eastern and Mexican cuisines, in sausages and a few cheeses.
Fennel
Fennel is a perennial plant with feathery leaves and tiny flowers long cultivated in India and China as a medicine and cure for witchcraft. Its seeds are greenish brown with prominent ridges and short, hair-like fibers. Their taste and aroma are similar to anise, though not as sweet. Whole seeds are widely used in Italian stews and sausages; central European cuisines use fennel with fish, pork, pickles and vegetables. Ground seeds can also be used in breads, cakes and cookies. The same plant produces a bulbous stalk used as a vegetable.
Fenugreek
Fenugreek is grown in Mediterranean countries since ancient times, is a small, beanlike plant with a tiny flower. The seeds, are available whole or ground, are pebble shaped and transfer their pale orange color to the foods with which they are cooked. Their flavor is bittersweet, like burnt sugar with a bitter aftertaste. Fenugreek is a staple in Indian cuisines, especially curries and chutneys.
File powder
File powder is the dried, ground leaf of the sassafras plant. Long used by Choctaw Indians, it is now most commonly used as a thickener and flavoring in Cajun and Creole cuisines. File is also used as a table condiment to acid a spicy note to stews, gumbo and the like. The powder forms strings if allowed to boil, so it should be added during the last minutes of cooking.
Galangal
Galangal is the rhizome of a plant native to India and Southeast Asia. The rhizome has a reddish skin, an orange or whitish flesh and a peppery, ginger-like flavor and piney aroma. Also known as galanga root, Thai ginger and Laos ginger, it is peeled and crushed for use in Thai, and Indonesian cuisines. Fresh ginger is an appropriate substitute.
Ginger
Ginger is a well-known spice obtained from the rhizome of a tall, flowering tropical plant. Fresh ginger is known as a "hand" because it looks vaguely like a group of knobby fingers. It has grayish-tan skin and a pale yellow, fibrous interior. Fresh ginger should be plump and firm with smooth skin. It should keep for about a month under refrigeration. Its flavor is fiery but sweet, with notes of lemon and rosemary. Fresh ginger is widely available and is used in Indian and Asian cuisines. It has a special affinity for chicken, beef and curries. Ginger is also available peeled and pickled in vinegar, candied in sugar or preserved in alcohol or syrup. Dried, ground ginger is a fine yellow powder widely used in pastries. Its flavor is spicier and not as sweet as fresh ginger.
Grains of Paradise
Grains of paradise are the seeds of a perennial reed-like plant indigenous to the West African coast. Related to cardamom, grains of paradise have a spicy, warm and slightly bitter flavor, similar to peppercorns. In fact, grains of paradise were traditionally used in place of black pepper and are also known as Guinea pepper or Melegueta pepper. Now enjoying a resurgence in popularity and increased availability, they are ground and used primarily in West African and Maghreb dishes, and in the spice blend known as ras el hanout.
Horseradish
Horseradish is the large off-white taproot of a hardy perennial (unrelated to radishes) that flourishes in cool climates. Fresh roots should be firm and plump; they will not have the distinctive horseradish aroma unless cut or bruised. The outer skin and inner core of a fresh horseradish root can have an unpleasant flavor and should be discarded. Typically used in Russian and Central European cuisines, especially as an accompaniment to roasted meats and fish and shellfish dishes, horseradish is usually served grated, creamed into a sauce or as part of a compound butter or mustard preparation. If horseradish is cooked, heat can destroy its flavor and pungency, so any horseradish should be added near the end of cooking.
Juniper
Juniper is an evergreen bush grown throughout the Northern Hemisphere. It produces round purple berries with a sweet flavor similar to pine. Juniper berries are used for flavoring gin and other alcoholic beverages, and are crushed and incorporated in game dishes, particularly venison and wild boar.
Mustard Seeds
Mustard seeds, available in black, brown and yellow, come from three different plants in the cabbage family. Mustard seeds are small, hard spheres with a bitter flavor. The seeds have no aroma, but their flavor is sharp and fiery hot. Yellow seeds have the mildest and black seeds the strongest flavor. All are sold whole and can be crushed for cooking. Mustard seeds are a standard component of pickling spices and are processed and blended for prepared mustards, which we discuss later. Ground or city mustard is a bright yellow powder made from a blend of ground seeds, wheat flour and turmeric.
Nutmeg
Nutmeg and mace come from the yellow plum-like fruit of a large tropical evergreen. These fruits are dried and opened to reveal the seed known as nutmeg. A bright red lacy coating or aril surrounds the seed; the aril is the spice mace. Whole nutmegs are oval and look rather like a piece of smooth wood. The flavor and aroma of nutmeg are strong and sweet, and a small quantity provides a great deal of flavor. Nutmeg should be grated directly into a dish as needed; once grated, flavor loss is rapid. Nutmeg is used in many European cuisines, mainly in pastries and sweets, but is also important in meat and savory dishes.
Mace
Mace is an expensive spice, with a flavor similar to nutmeg but more refined. It is almost always purchased ground and retains its flavor longer than other ground spices. Mace is used primarily in pastry items.
Peppercorns
Peppercorns are the berries of a vine plant (piper nigrum) native to tropical Asia. Peppercorns should not be confused with the chile (capsicum) peppers discussed earlier. Peppercorns vary in size, color, pungency and flavor. Many of these differences are the result of variations in climate and growing conditions. Good-quality pepper is expensive and should be purchased whole and ground fresh in a pepper mill as needed. Whole peppercorns will last indefinitely if kept dry. They should be stored well covered in a cool, dark place.
Black and white peppercorns
Black and white peppercorns are produced from the same plant, but are picked and processed differently. For black peppercorns, the berries are picked when green and simply dried whole in the sun. Black pepper has a warm, pungent flavor and aroma. Tellicheny peppercorns from the southwest coast of India are generally considered the finest black peppercorns in the world and are priced accordingly. For white peppercorns, the berries are allowed to ripen until they turn reel. The ripened berries are allowed to ferment, then the outer layer of skin is washed off. Now, white pepper may be produced by mechanically removing the outer skin from black peppercorns. This is not true white pepper, and the resulting product should be labeled "decorticated." White pepper has fewer aromas than black pepper but is useful in white sauces or when the appearance of black speckles is undesirable.
Green peppercorns
Green peppercorns are unripened berries that are either freeze-dried or pickled in brine or vinegar. Pickled green peppercorns are soft, with a fresh, sour flavor similar to capers. They are excellent in spiced butters and sauces or with fish.
Pink peppercorns
Pink peppercorns are actually the berries of a South American tree, not a vine pepper plant. Pink peppercorns are available dried or pickled in vinegar. Although they are attractive, their flavor is bitter and pine-like, with less spiciness than true pepper.
Szechuan pepper
Szechuan pepper is the dried red berries of the prickly ash tree native to China. Also known as anise pepper and Chinese pepper, the berries have an extremely hot, peppery, spicy flavor with citrus overtones and are used in Chinese cuisines and as part of Chinese five-spice powder.
Poppy Seeds
Poppy seeds are the ripened seeds of the opium poppy, which flourishes in the Middle East and India. (When ripe, the seeds do not contain any of the medicinal alkaloids found elsewhere in the plant.) The tiny blue-gray seeds are round and hard with a sweet, nutty flavor. Poppy seeds are used in pastries and breads.
Saffron
Saffron comes from the dried stigmas of the saffron crocus. Each flower bears only three thread like stigmas, and each must be picked by hand. It takes about 250,000 flowers to produce one pound of saffron, making it the most expensive spice in the world. Beware of bargains; there is no such thing as cheap saffron. Luckily, a tiny pinch is enough to color and flavor a large quantity of food. Good saffron should be a brilliant orange color, not yellow, with a strong aroma and a bitter, honey-like taste. Saffron produces a yellow dye that diffuses through any warm liquid. Valencia or Spanish saffron is considered the finest. It is commonly used with fish and shellfish (a necessity for bouillabaisse) and rice dishes such as paella and risotto. When using saffron threads, first crush them gently, then soak them in some hot liquid from the recipe. Powdered saffron is less expensive but more easily adulterated. It may be added directly to the other ingredients when cooking.
Crocus Plant Saffron Spice
Sesame Seeds
Sesame seeds, also known as benne seeds, are native to India. They are small, flat ovals, with a creamy white color. Their taste is nutty and earthy, with a pronounced aroma when roasted or ground into a paste (known as tahini). Sesame seeds are the source of sesame oil, which has a mild, nutty flavor and does not go rancid easily. Sesame seeds are roasted and used in or as a garnish for breads and meat dishes. They are popular in Indian and Asian cuisines, with a black variety of seeds most popular as a Japanese condiment.
Tamarind
Tamarind also known as an Indian date, is the brown, bean-shaped pod of the tamarind tree, which is native to Africa. Although naturally sweet, tamarind also contains 12% tartaric acid, which makes it extremely tart. It is commonly used in Indian curries and Mediterranean cooking as a souring agent and in the West Indies in fruit drinks. Tamarind is sold as a concentrate or in sticky blocks of crushed pods, pulp and seeds, which should be soaked in warm water for about five minutes, then squeezed through a sieve. Tamarind's high pectin content is useful in chutneys and jams, and it is often included in barbeque sauces and marinades. It is a key ingredient in Worcestershire sauce.
Turmeric
Turmeric, also known as Indian saffron, is produced from the rhizome of a flowering tropical plant related to ginger. It has a mild, woodsy aroma. It is most often available dried and usually ground although fresh turmeric appears in ethnic markets. Turmeric is renowned for its vibrant yellow color and is used as a food coloring and dye. Turmeric's flavor is distinctive and strong; it should not be substituted for saffron. Turmeric is a traditional ingredient in Indian curries, to which it imparts color as well as flavor.
Wasabi
Wasabi is a pale green root similar, but unrelated, to horseradish. It has a strong aroma and a sharp, cleansing flavor with herbal overtones that is a bit hotter than that of horseradish. Fresh wasabi is rarely found outside Japan, but tins of powder and tubes of paste are readily available. It is commonly served with sushi and sashimi and can be used to add a spicy Asian note to other dishes, such as mashed potatoes or a compound butter. | textbooks/workforce/Food_Production_Service_and_Culinary_Arts/Culinary_Foundations_(Cheramie_and_Thibodeaux)/09%3A_Flavor_and_Taste/9.02%3A_Flavorings_-_Herbs_and_Spices.txt |
Herb and Spice Blends
Many cuisines have created recognizable combinations of flavors that are found in a variety of dishes. Although many of these blends are available already prepared for convenience, most can be mixed by the chef as need. (And commercial blends can contain large amounts of salt.) Chinese five-spice powder is a combination of equal parts finely ground Szechuan pepper, star anise, cloves, cinnamon and fennel seeds. This blend is widely used in Chinese and some Vietnamese foods and is excellent with pork and in pates.
Curry powder is a European invention that probably took its name from the Tamil word Kari, meaning "sauce." Created by 19th-century Britons returning from colonial India, it was meant to be the complete spicing for a "curry" dish. There are as many different formulas for curry powder as there are manufacturers, some mild and sweet (Bombay or Chinese style), others hot and pungent (Madras style). Typical ingredients in curry powder are black pepper, cinnamon, cloves, coriander, cumin, ginger, mace and turmeric.
Fine herbs (Fr. fines herbes) are a combination of parsley, tarragon, chervil and chives widely used in French cuisine. The mixture is available dried, or it can be created from fresh ingredients.
Jamaican jerk seasoning is a powdered or wet mixture used on the Caribbean island of the same name made from a combination of spices that typically includes thyme, ground spices such as allspice, cinnamon, cloves, and ginger as well as onions and garlic. Chicken and pork are typically rubbed or marinated in the blend, then grilled.
Herbes de Provence is a blend of dried herbs commonly grown and used in southern France. Commercial blends usually include thyme, rosemary, bay leaf, basil, fennel seeds, savory, and lavender. The herb blend is used with grilled or roasted meat, fish or chicken; in vegetable dishes; on pizza; and even in steamed rice and yeast breads.
Italian seasoning blend is a commercially pre pared mixture of dried basil, oregano, sage, mar jo ram, rosemary, thyme, savory and other herbs associated with Italian cuisine.
Masala is a flavorful, aromatic blend of roasted and ground spices used in Indian cuisines. A garam masala is a masala made with hot spices (garam means warm or hot). A dry garam masala usually contains peppercorns, cardamom, cinnamon, cloves, coriander, nutmeg, turmeric, bay leaves and fennel seeds and is added toward the end of cooking or sprinkled on the food just before service. Adding coconut milk, oil or sometimes tamarind water to a dry garam masala makes a wet garam masala. A wet garam masala is typically added at the start of cooking.
Pickling spice, as with other blends, varies by manufacturer. Most pickling spice blends are based on black peppercorns and red chiles, with some or all of the following added: allspice, cloves, ginger, mustard seeds, coriander seeds, bay leaves and dill. These blends are useful in making cucumber or vegetable pickles as well as in stews and soups.
Quatre-epices, literally "four spices” in French and also the French word for allspice, is a peppery mixture of black peppercorns with lesser amounts of nutmeg, cloves and dried ginger. Sometimes cinnamon or allspice is included. Quatre-epices is used in charcuterie and long-simmered stews.
Ras el hanout is a common Moroccan spice blend varying greatly from supplier to supplier. It typically contains 20 or more spices, such as turmeric, cinnamon, cloves, grains of paradise, coriander, cumin, cardamom, peppercorns, dried chiles, dried flower petals and, allegedly, an aphrodisiac or two. It is sold whole and ground by the cook as necessary to flavor stews, rice, couscous, and game dishes.
Seasoned salts are commercially blended products containing salt and one or more natural flavoring ingredients such as garlic, spices or celery seeds and, often, monosodium glutamate.
Storing Herbs and Spices
Fresh herbs should be kept refrigerated at 34°F-4 0°F (2°C-4 °C). Large bouquets can be stored upright, their leaves loosely covered with plastic wrap and their stems submerged in water. Smaller bunches should be stored loosely covered with a clamp towel. You can dry excess fresh herbs for later use in an electric dehydrator. You can also spread them out on baking sheets in a 100°F (38°C) oven.
Dried herbs and spices should be stored in airtight, opaque containers in a cool, dry place. Avoid light and heat, both of which destroy delicate flavors. If stored properly, dried herbs should last for two to three months.
Using Herbs and Spices
Herbs and spices are a simple, inexpensive way to bring individuality and variety to foods. They add neither fat nor sodium and virtually no calories to foods; most contain only 3 to 10 calories per teaspoon.
Although the flavors and aromas of fresh herbs are generally preferred, dried herbs are widely used because they are readily available and convenient. Use less dried herb than you would fresh herb. The loss of moisture strengthens and concentrates the flavor in dried herbs. In general, use only one-half to one-third as much dried herb as fresh in any given recipe. For example, if a recipe calls for 1-tablespoon of fresh basil, substitute only 1-teaspoon of dried basil. More can usually be added later if necessary. The delicate aroma and flavors of fresh herbs is volatile. Most fresh herbs such as chives, parsley, cilantro, basil and tarragon are best when added at the end of cooking.
Spices are often available whole or ground. Once ground, they lose their flavors rapidly, however. Whole spices should keep their flavors for at least six to nine months if stored properly. Stale spices lose their spicy aroma and develop a bitter or musty aftertaste. Discard them.
Most dried spices need to be added early in order for their flavor to develop during the cooking. Whole spices take the longest; ground spices release their flavor more quickly. In some preparations, Indian curries for example, ground spices are first cooked in oil to release their aromas before being added to a dish. However, some dried spices such as black pepper may become bitter when cooked for an extended period. In uncooked dishes that call for ground spices (for example, salad dressings), the mixture should be allowed to stand for several hours to develop good flavor.
Creating dishes with appealing and complex flavors comes with practice and a solid understanding and appreciation of flavoring ingredients. Although some flavoring combinations are timeless - rosemary with lamb, dill with salmon, nutmeg with spinach, and caraway with rye bread - less common pairings can be equally delicious and far more exciting. Chefs must be willing and able to experiment with new flavors. First, they must become familiar with the distinctive flavors and aromas of a herb, spice, condiment, vinegar or the like.
When experimenting, always bearing in mind the following guidelines:
1. Flavorings should not hide the taste or aroma of the primary ingredient. Balance flavoring combinations so as not to overwhelm the palate.
2. Flavorings should not be used to disguise poor quality or poorly prepared products.
3. Flavorings should be added sparingly when foods are to be cooked over an extended time.
4. When reduced during cooking, flavorings can intensify and overpower the dish.
5. Taste and season foods frequently during cooking.
Even in a well-tested recipe, the quantity of flavorings may need to be adjusted because of a change in brands or the condition of the ingredients. A chef should strive to develop his or her palate to recognize and correct subtle variances as necessary. | textbooks/workforce/Food_Production_Service_and_Culinary_Arts/Culinary_Foundations_(Cheramie_and_Thibodeaux)/09%3A_Flavor_and_Taste/9.03%3A_Blends_and_Storage_of_herbs_and_spices.txt |
Salt
Salt is the most basic and universal seasoning. It preserves foods, heightens their flavors and provides the distinctive taste of saltiness. The presence of salt can be tasted easily but not smelled. Salt suppresses bitter flavor, making the sweet and sour ones more prominent. The flavor of salt will not evaporate or dissipate during cooking so it should be added to foods carefully, according to taste. Remember, more salt can always be added to a dish but too much salt cannot be removed nor can its flavor be masked if too much salt has been added.
Culinary or table salt is sodium chloride (NaCl), one of the minerals essential to human life. Salt contains no calories, proteins, fats or carbohydrates. It is available from several sources, each with its own flavor and degree of saltiness. Rock salt, mined from underground deposits, is available in both edible and nonedible forms. It is used in ice cream churns, for thawing frozen sidewalks and, in edible form, in salt mills.
Common kitchen or table salt is produced by pumping water through underground salt deposits, then bringing the brine to the surface to evaporate, leaving behind crystals. Chemicals are usually added to prevent table salt from absorbing moisture and thus keep it free flowing. Iodized salt is commonly used in the United States. The iodine has no effect on the salt's flavor or use; it is simply added to provide an easily available source of iodine, an important nutrient, to a large number of people.
Kosher salt has large, irregular crystals and is used in the "koshering " or curing of meats. It is purified rock salt containing no iodine or additives. It is a perfect substitution for common kitchen salt. Some chefs prefer it to table salt because they prefer its flavor and it dissolves more easily than other salts.
Sea salt is obtained, not surprisingly, by evaporating seawater. The evaporation can be clone naturally by drying the salt in the sun (unrefined sea salt) or by boiling the salty liquid (refined sea salt). Unlike other table salts, unrefined sea salt contains additional mineral salts such as magnesium, calcium and potassium, which give it a stronger, more complex flavor and a grayish-brown color. The region where it is produced can also affect its flavor and color. For example, salt from the Mediterranean Sea will taste different from salt obtained from the Indian Ocean or the English Channel.
Sel gris is a sea salt harvested off the coast of Normandy, France. It is slightly wet and takes its gray color from minerals in the clay from which it is collected. Fleur de sel, which means "flower of salt," is s alt that collects on rocks in the sel gris marshes. It forms delicate crystals and has little color because it has not been exposed to the clay.
Some specialty salts are mined from the earth, such as that from the foothills of the Himalayan Mountains. The presence of iron and copper along with other minerals gives Himalayan salt a pink hue and distinct flavor. Black salt, common in traditional Indian recipes, is mined rock salt; minerals and other components in the salt give it a dark color and sulfurous taste. Smoked salt is a type of flavored salt made by smoking the salt over a smoldering fire. It can also be made by adding liquid smoke to a salt solution before it is evaporated.
Sea salt is considerably more expensive than other table salts and is often reserved for finishing a dish or used as a condiment. Because it is nonorganic, salt keeps indefinitely. It will, however, absorb moisture from the atmosphere, which prevents it from flowing properly. Salt is a powerful preservative; its presence stops or greatly slows down the growth of many undesirable organisms. Salt is used to preserve meats, vegetables and fish. It is also used to develop desirable flavors in bacon, ham, cheeses and fish products as well as pickled vegetables.
Notes about Flavor -
Flavor is to food what hue is to color. It is what timbre is to music. (Flavor is adjective; food is noun.) Each ingredient has its own particular character, which is altered by every other ingredient it encounters. A secret ingredient is one that mysteriously improves the flavor of a dish without calling attention to itself. It is either undetectable or extremely subtle, but its presence is crucial because the dish would not be nearly as good without it.
Primary flavors are those that are obvious, such as the flavors of chicken and tarragon in a chicken tarragon, shrimp and garlic in a shrimp scampi, or beef and red wine in a beef a la Bourguignonne. Secret ingredients belong to the realm of secondary flavors. However obvious it is that you need tarragon to prepare a chicken tarragon, you would not achieve the most interesting result using only tarragon. Tarragon, in this case, needs secondary ingredients-a hint of celery seed and anise- to make it taste more like quintessential tarragon and at the same time more than tarragon. In this way, primary flavors often depend on secret ingredients to make them more interesting and complex. Using only one herb or spice to achieve a certain taste usually results in a lackluster dish-each mouthful tastes the same. Whether they function in a primary or secondary way, flavors combine in only three different ways: They marry, oppose, or juxtapose.
When flavors marry, they combine to form one taste. Some secondary flavors marry with primary ones to create a new flavor greater than the sum of its parts, and often two flavors can do the job better than one. It may sound like an eccentric combination, but vanilla marries with the flavor of lobster, making it taste more like the essence of lobster than lobster does on its own. Additionally when ginger and molasses marry, they create a flavor superior to either alone.
Opposite flavors can highlight or cancel each other; they can cut or balance each other. Sweet/sour, sweet/salty, sweet/hot, salty/sour, and salty/tart are all opposites. Salt and sugar are so opposed, in fact, that when used in equal amounts they cancel each other entirely. Sweet relish helps cancel the salty flavor of hot dogs. Chinese sauces usually contain some sugar to help balance the saltiness of soy sauce.
Knowing how to combine many flavors and aromas to achieve a simple and pure result (and knowing when not to combine flavors) will make you a better, more confident cook. Good cooks over the centuries have known these things intuitively but they have had neither the huge variety of ingredients nor the knowledge of world cuisines that we have today.
From: Chef Michael Roberts, author of Secret Ingredients.
Oils
Oils are a type of fat that remains liquid at room temperature. Cooking oils are refined from various seeds, plants and vegetables. When purchasing oils, consider their use, smoke point, flavor and cost. Fats, including oils and shortenings, are manufactured for specific purposes such as deep-frying, cake baking, salad dressings and sautéing. Most food service operations purchase different ones for each of these needs. Fats break clown at different temperatures. When fats break down, their chemical structure is altered - the triglyceride molecules that make up fat are converted into individual fatty acids. These acids add undesirable flavors to the fat and can ruin the flavor of the food being cooked. The temperature at which a given fat begins to break down and smoke is known as its smoke point. Select fats with higher smoke points for high-temperature cooking such as deep-frying and sautéing.
The flavor and cost of each oil must be considerations. For example, both corn oil and walnut oil can be used in a salad dressing. Their selection may depend on balancing cost (corn oil is less expensive) against flavor (walnut oil has a stronger, more distinctive flavor).
Terms
• smoke point the temperature at which a fat begins to break down and smoke.
• flash point the temperature at which a fat ignites and small flames appear on the surface of the fat.
• shortening (1) a white, flavorless, solid fat formulated for baking or deep-frying; (2) any fat used in baking to tenderize the product by shortening gluten strands.
When fats spoil, they go rancid. Rancidity is a chemical change caused by exposure to air, light or heat. It results in objectionable flavors and odors. Different fats turn rancid at different rates, but all fats benefit from refrigerated storage away from moisture, light and air. (Some oils are packaged in colored glass container s because certain tints of green and yellow block the damaging light rays that can cause an oil to go rancid.) Although oils may become thick and cloudy under refrigeration, this is not a cause for concern. The oils will return to their clear, liquid states at room temperature. Stored fats should also be covered to prevent them from absorbing odors.
Vegetable oils are extracted from a variety of plants, including corn, cottonseed, peanuts, grape seeds, sesame seeds and soybeans, by pressure or chemical solvents. The oil is then refined and cleaned to remove unwanted colors, odors or flavors. Vegetable oils are virtually odorless and have a neutral flavor. Because they contain no animal products, they are cholesterol-free. If a commercial product contains only one type of oil, it is labeled "pure" (as in "pure corn oil") Products labeled "vegetable oil" are blended from several sources. Products labeled "salad oil" are highly refined blends of vegetable oil.
Canola oil is processed from rapeseeds. Its popularity is growing rapidly because it contains no cholesterol and has a high percentage of monounsaturated fat. Canola oil is useful for frying and general cooking because it has no flavor and a high smoke point.
Nut oils are extracted from a variety of nuts and are usually packaged as a "pure" product, never blended. A nut oil should have the strong flavor and aroma of the nut from which it was processed. Popular examples are walnut and hazelnut oils. These oils are used to give flavor to salad dressings, marinades and other dishes. Heat diminishes their flavor, so nut oils are not recommended for frying or baking. Nut oils tend to go rancid quickly and therefore are usually packaged in small containers.
Olive oil is the only oil that is extracted from a fruit rather than a seed, nut or grain. Olive oil is produced primarily in Spain, Italy, France, Greece and North Africa; California produces a relatively minor amount of olive oil. Like wine, olive oils vary in color and flavor according to the variety of tree, the ripeness of the olives, the type of soil, the climate and the producer’s preferences. Colors range from dark green to almost clear, depending on the ripeness of the olives at the time of pressing and the amount of subsequent refining. Color is not a good indication of flavor, however, flavor is ultimately a matter of personal preference. A stronger-flavored oil may be desired for some foods, while a milder oil is better for others. Good olive oil should be thicker than refined vegetable oils, but not so thick that it has a fatty texture.
The label designations - extra virgin, virgin and pure refer to the acidity of the oil (a low acid content is preferable) and the extent of processing used to extract the oil. The first cold pressing of the olives results in virgin oil. (The designation "virgin" is used only when the oil is 100% unadulterated olive oil, unheated and without any chemical processing.) Virgin oil may still vary in quality depending on the level of free acidity, expressed as oleic acid. Extra virgin oil is virgin oil with not more than 1% free acidity (oleic acid); virgin oil may have up to 3%. Pure olive oil is processed from the pulp left after the first pressing using heat and chemicals. Pure oil is lighter in flavor and less expensive than virgin oil.
Flavored oils, also known as infused oils, are an interesting and increasingly popular condiment. These oils may be used as a dip for breads, a cooking medium or a flavoring accent in marinades, dressings, sauces or other dishes. Flavors include basil and other herbs, garlic, citrus and spice. Flavored oils are generally prepared with olive oil for additional flavor or canola oil, both considered more healthful than other fats.
Top-quality commercially flavored oils are prepared by extracting aromatic oils from the flavoring ingredients and then emulsifying them with a high-grade oil; any impurities are then removed by placing the oil in a centrifuge. Using the aromatic oils of the flavoring ingredients yields a more intense flavor than merely steeping the same ingredients in the oil. Flavored oils should be stored as you would any other high-quality oil.
Condiments
Strictly speaking, a condiment is any food added to a dish for flavor, including herbs, spices and vinegars. Today, however, condiments more often refer to cooked or prepared flavorings, such as prepared mustards, relishes, bottled sauces and pickles served to accompany foods. We discuss several frequently used condiments here. These staples may be used to alter or enhance the flavor of a dish during cooking, or added to a completed dish at the table.
Chutney (from the Hindi word for catnip) is a pungent relish made from fruits, spices and herbs and is frequently used in Indian cooking.
Fermented black bean sauce is a Chinese condiment and flavoring ingredient made from black soybeans that have been heavily salted, then fermented and either slightly mashed (whole bean sauce) or pureed (paste). Both versions are usually mixed with hoisin, chile sauce or minced garlic to produce a sauce that has an intense, pungent, salty flavor. Yellow bean sauces are similar, but milder and sweeter.
Fish sauce is the liquid drained from fermenting salted anchovy-like fish. It is a thin, golden to light brown liquid with a very pungent odor and salty flavor. There is no substitute for the savory richness that it acids to food and it is considered an essential flavoring and condiment throughout South east Asia, where it is used in and served with most every sort of dish.
Ketchup (also known as catsup or catchup) originally referred to any salty extract from fish, fruits or vegetables. Prepared tomato ketchup is really a sauce, created in America and used worldwide as a flavoring ingredient or condiment. It is bright red and thick, with a tangy, sweet-sour flavor. Ketchup can be stored either in the refrigerator or at room temperature; it should keep well for up to four months after opening. Ketchup does not turn rancid or develop mold, but it will darken and lose flavor as it ages.
Prepared mustard is a mixture of crushed mustard seeds, vinegar or wine and salt or spices. It can be flavored in many ways- with herbs, onions, peppers and even citrus zest. It ca n be a smooth paste or coarse and chunky, depending on how finely the seeds are ground and whether the skins are strained out. Prepared mustard gets its tangy flavor from an essential oil that forms only when the seeds are crushed and mixed with water. Prepared mustard can be used as a condiment, particularly with meat and charcuterie items, or as a flavoring ingredient in sauces, stews and marinades.
Dijon mustard takes its name from a town and the surrounding region in France that produces about half of the world's mustard. French mustard labeled as "Dijon" must by law, be produced ‘only’ in that region. Dijon and Dijon-style mustards are smooth with a rich, complex flavor.
English and Chinese mustards are made from mustard flour and cool water. They are extremely hot and powerful. American or "ballpark" mustard is mild and vinegary with a bright yellow color. Unless it contains a high percentage of oil, mustard never really spoils; its flavor just fades away.
Vinegars
Vinegar is a thin, sour liquid used for thousands of years as a preservative, cooking ingredient, condiment and cleaning solution. Vinegar is obtained through the fermentation of wine or other alcoholic liquid. Bacteria attack the alcohol in the solution, turning it into acetic acid. No alcohol remains when the transformation is complete. The quality of vinegar depends on the quality of the wine or other liquid on which it is based. Vinegar flavors are as varied as the liquids from which they are made.
Vinegars should be clear and clean looking, never cloudy or muddy. Commercial vinegars are pasteurized, so an unopened bottle should last indefinitely in a cool, dark place. Once opened, vinegars should last about three months if tightly capped. Any sediment that develops can be strained out; if mold develops, discard the vinegar.
Wine vinegars are as old as wine itself. They may be made from white or red wine, sherry or even Champagne, and should bear the color and flavor hallmarks of the wine used. Wine vinegars are preferred in French and Mediterranean cuisines.
Malt vinegar is produced from malted barley. Its slightly sweet, mild flavor is used as a condiment, especially with fried foods.
Distilled vinegar, made from grain alcohol, is completely clear with a stronger vinegary flavor and higher acid content than other vinegars. It is preferred for pickling and preserving.
Cider vinegar is produced from unpasteurized apple juice or cider. It is pale brown in color with a mild acidity and fruity aroma. Cider vinegar is particularly popular in the United States.
Rice vinegar is a clear, slightly sweet product brewed from rice wine. Its flavor is clean and elegant, making it useful in a variety of dishes, especially those of Japanese or Asian origin.
Flavored vinegars are simply traditional vinegars in which herbs, spices, fruits or other foods are steeped to infuse their flavors. They are easily produced from commercial wine or distilled vinegars, using any herb, spice or fruit desired. Inferior flavored vinegars are made by adding the desired flavoring to lowgrade vinegar. The use of flavored vinegars is extremely popular but definitely not new. Clove, raspberry and fennel vinegars were sold on the streets of Paris during the 13th century. Making fruit-flavored vinegars was also one of the responsibilities of housewives during the 18th and 19th centuries.
Balsamic vinegar is newly popular in the United States, though it has been produced in Italy for more than 800 years. To produce traditional balsamic vinegar, reel or white wine made from specially cultivated grapes (white Trebbiano and red Lambrusco grapes among others), is reduced, then aged in a succession of wooden barrels made from a variety of woods-oak, cherry, locust, ash, mulberry and juniper- for at least 4, but sometimes up to 50, years. The resulting liquid is dark reddish-brown and sweet. Balsamic vinegar has a high acid level, but the sweetness covers the tart flavor, making it very mellow. True balsamic is extremely expensive because of the long aging process and the small quantities available. Most of the commercial products imported from Italy are now made by a quick carmelization and flavoring process. Balsamic is excellent as a condiment or seasoning and has a remarkable affinity for tomatoes and strawberries. | textbooks/workforce/Food_Production_Service_and_Culinary_Arts/Culinary_Foundations_(Cheramie_and_Thibodeaux)/09%3A_Flavor_and_Taste/9.04%3A_Salt_Oils_Condiments_and_Vinegars.txt |
Thumbnail: Roasted chicken (Unsplash License; Amanda Lim via Unsplash)
10: Breakfast and Roasting
Nature designed eggs as the food source for developing chicks. Eggs, particularly chicken eggs, are also an excellent food for humans because of their high protein content, low cost and ready availability. They are extremely versatile and are used throughout the kitchen, either served alone or as ingredients in a prepared dish. Eggs are used to provide texture, flavor, structure, moisture and nutrition in everything from soups and sauces to breads and pastries.
Egg dishes are, of course, most often associated with the meals breakfast and brunch. But food service operations must offer a variety of breakfast options to appeal to a wide range of consumers. Breakfast cookery is often one of the first line positions a new cook will be offered. This important duty requires speed, timing and precision and can help an apprentice or beginning cook develop organized, efficient work habits.
This chapter discusses cooking methods used for eggs as well as breakfast meats, griddlecakes, crepes, cereals and the beverages coffee and tea.
Egg Composition
The primary parts of an egg are the shell, yolk and albumen.
The shell, composed of calcium carbonate, is the outermost covering of the egg. It prevents microbes from entering and moisture from escaping, and protects the egg during handling and transport. The breed of the hen determines shell color; for chickens, it can range from bright white to brown. Shell color has no effect on quality, flavor or nutrition:
The yolk is the yellow portion of the egg. It constitutes just over one -third of the egg and contains three -fourths of the calories, most of the minerals and vitamins and all the fat. The yolk also contains lecithin, the compound responsible for emulsification in products such as hollandaise sauce and mayonnaise . Egg yolk solidifies (coagulates) at temperatures between 149°F and 158°F (65°C and 70°C). Although the color of a yolk may vary depending on the hen's feed, color does not affect quality or nutritional content.
The albumen is the clear portion of the egg and referred to as the egg white. It constitutes about two-thirds of the egg and contains more than half of the protein and riboflavin. Egg white coagulates, becoming firm and opaque, at temperatures between 144°F and 149°F (62°C and 65°C).
Eggs are sold in Jumbo, Extra Large, Large, Medium, Small and Peewee sizes, as determined by weight per dozen. See Figure 21.2. Food service operations generally use Large eggs, which weigh 24 ounces per dozen. Other sizes are based on plus or minus 3 ounces per dozen; Medium eggs weigh 21 ounces per dozen while Extra Large eggs weigh 27 ounces per dozen.
extension.illinois.edu
The yolk is the yellow portion of the egg. It constitutes just over one -third of the egg and contains three -fourths of the calories, most of the minerals and vitamins and all the fat. The yolk also contains lecithin, the compound responsible for emulsification in products such as hollandaise sauce and mayonnaise. Egg yolk solidifies (coagulates) at temperatures between 149°F and 158°F (65°C and 70°C). Although the color of a yolk may vary depending on the hen's feed, color does not affect quality or nutritional content. The albumen is the clear portion of the egg and is often referred to as the egg white. It constitutes about two-thirds of the egg and contains more than half of the protein and riboflavin. Egg white coagulates, becoming firm and opaque, at temperatures between 144°F and 149°F.
Grading
Eggs are graded by the USDA or a state agency following USDA guidelines. The grade AA, A, or B is given to an egg based on interior and exterior quality, not size. Grade has no effect on nutritional values.
Storage
Improper handling quickly diminishes egg quality. Eggs should be stored at temperatures below 45°F (7°C) and at a relative humidity of 70 to 80 percent. Eggs will age more during one day at room temperature than they will during one week under proper refrigeration. As eggs age, the white becomes thinner and the yolk becomes flatter. Although this will change the appearance of poached or fried eggs, age has little effect on nutrition or behavior during cooking procedures. Older eggs, however, should be used for hard cooking, as the shells are easier to remove than those on fresh eggs are.
Cartons of fresh, uncooked eggs will keep for at least four to five weeks beyond the pack date if properly refrigerated. Hard-cooked eggs left in their shells and refrigerated should be used within one week. Store eggs away from strongly flavored foods to reduce odor absorption. Rotate egg stock to maintain freshness. Do not use dirty, cracked or broken eggs, as they may contain bacteria or other contaminants. Frozen eggs should be thawed in the refrigerator and used only in dishes that will be thoroughly cooked, such as baked products.
Other Eggs
When most people refer to an "egg," they mean a chicken's egg. However, other eggs are sometimes used in the kitchen:
• Bantam egg: The egg from a breed of small chicken; it is about half the size of a regular chicken egg and has the same characteristics.
• Duck egg: An egg with an off-white shell and a richer flavor and higher fat content than a chicken's egg; when it is boiled, the white turns bluish and the yolk turns red-orange.
• Goose egg: A white-shelled egg that is four to five times as large as a chicken egg; it also has a somewhat richer flavor.
• Guinea fowl egg: An egg with an ivory shell flecked with brown; its flavor is more delicate than that of a chicken egg.
• Gull egg: An egg whose shell is covered with light to dark brown blotches; it comes in various small sizes and has a slightly fishy flavor.
• Ostrich egg: An egg that is 20 times as large as a chicken egg and has a thick, ivory-colored shell; its flavor is similar to that of a chicken egg.
• Partridge egg: A small egg with a white, buff or olive shell; it has a mild flavor.
• Quail egg: A small egg with a speckled brown shell; it has a rich flavor.
• Turkey egg: A large egg with a brown shell; it has a delicate flavor.
• Turtle egg: A reptile's egg with a soft shell that is buff or speckled; it has a mild, rich flavor.
Egg Varieties. pysankybasics.com
Sanitation
Eggs are a potentially hazardous food. Rich in protein, they are an excellent breeding ground for bacteria. Salmonella is of particular concern with eggs and egg products because the bacteria are commonly found in a chicken's intestinal tract. Although shells are cleaned at packinghouses, some bacteria may remain. Therefore, to prevent contamination, it is best to avoid mixing a shell with the liquid egg.
Inadequately cooking or improperly storing eggs may lead to food-borne illnesses. USDA guidelines indicate that pasteurization is achieved when the whole egg stays at a temperature of 140°F (60°C) for Y/2 minutes. Hold egg dishes below 40°F (4°C) or above 140°F (60°C). Never leave an egg dish at room temperature for more than one hour, including preparation and service time. Never reuse a container after it has held raw eggs without thoroughly cleaning and sanitizing it.
Egg Products
Food service operations often want the convenience of buying eggs out of the shell in the exact form needed: whole eggs, yolks only or whites only. These processed items are called egg products and are subject to strict pasteurization standards and USDA inspections. Egg products can be frozen, refrigerated or dried. Precooked, pre-portioned, and blended egg products are also available.
Nutrition
Eggs contain vitamins A, D, E and K, and the B-complex vitamins. They are rich in minerals and contain less cholesterol now than previously. Research indicates that the cholesterol in whole eggs does not affect serum cholesterol as much as was once feared. In fact, the American Heart Association now suggests that it is acceptable to consume up to four egg yolks per week as part of a balanced diet. Egg whites do not contain cholesterol and are often added to egg dishes such as omelets to reduce total fat content.
Dry Heating Cooking
Baking
Shirred Eggs
Baked eggs, also referred to as shirred eggs, are normally prepared in individual ramekins or baking dishes. The ramekins can be lined or partially filled with ingredients such as bread, ham, creamed spinach or artichokes. The eggs are often topped with grated cheese, fresh herbs or a sauce. When properly cooked, the egg whites should be set while the yolks are soft and creamy.
Preparation
1. Coat each ramekin with melted butter. Add flavoring ingredients as desired.
2. Break one or two eggs into each ramekin. Do not break the yolks. Season with salt and pepper.
3. Bake the eggs until the white is firm, approximately 12- 15 minutes. Approximately 3- 5 minutes before the eggs are done, add cream or top the eggs with grated cheese , diced ham, fresh herbs or other ingredients as desired.
Shirred Eggs. eggs.ca
Sauteing
Scrambled Eggs
Scrambled eggs are eggs whisked with seasonings and then sautéed. They must be stirred nearly constantly during cooking. The finished eggs should be light and fluffy with a tender, creamy texture. A small amount of milk or cream may be added to the eggs to provide a more delicate finished product. Overcooking or cooking at too high a temperature causes the eggs to become tough and rubbery.
Scrambled eggs are often flavored by sautéing other foods (for example), onions, mushrooms or diced ham) in the pan before adding the eggs or by adding other foods (for example, grated cheeses or herbs) to the eggs just before cooking is complete. Suggested additions include finely diced bell peppers, onions, mush rooms, zucchini or tomatoes; cottage cheese or any variety of shredded firm cheese; crumbled bacon; diced ham, turkey or beef; bits of smoked salmon, cooked shrimp or cooked sausage; and fresh herbs.
Scrambled eggs can also be prepared using only egg whites. Because all of an egg's fat is stored in the yolk, no-yolk scrambled egg dishes are lower in fat, cholesterol and calories. Water or nonfat milk can be used in place of whole milk or cream to further reduce the fat and calorie content of the finished dish. Re member that egg whites coagulate at a lower temperature than yolks, so adjust the cooking time and temperature accordingly.
Preparation
1. Break the eggs into a mixing bowl. Season lightly with salt and pepper. Add 1 scant tablespoon (12 milliliters) milk or cream per egg and whisk everything together.
2. Heat a sauté pan, add clarified butter or oil and heat until the fat begins to sizzle.
3. Sauté any additional ingredients in the hot fat.
Scrambled eggs and Toast. browneyedbaker.com
Frittatas
Frittatas are essentially open -faced omelets of Spanish-Italian heritage. They may be cooked in small pans as individual portions, or in large pans, and then cut into wedges for service. A relatively large amount of hearty ingredients is mixed directly into the eggs. The eggs are first cooked on the stovetop, and then the pan is transferred to an oven or placed under a salamander or broiler to finish cooking.
Preparation
1. Fully cook any meats and blanch or otherwise prepare any vegetables that will be incorporated into the frittata .
2. Heat a sauté pan and add clarified butter.
3. Whisk the eggs, flavorings and any other ingredients together; pour into the pan.
4. Stir gently until the eggs begin to set. Gently lift cooked egg at the edge of the frittata so that raw egg can run underneath. Continue cooking until the eggs are almost set.
5. Place the pan in a hot oven or underneath a salamander or broiler to finish cooking and lightly brown the top.
6. Slide the finished frittata out of the pan onto a serving platter.
Vegetable Frittata. bbcgoodfood.com
Pan-Frying
Pan-fried eggs are commonly referred to as sunny side up or over easy, over medium or over hard. These are visibly different products produced with proper timing and technique. Very fresh eggs are best for pan-frying, as the yolk holds its shape better and the white spreads less.
Sunny-side-up eggs are not turned during cooking; their yellow yolks remain visible. They should be cooked over medium -low heat long enough to firm the whites and partially firm the yolks: approximately 4 minutes if cooked on a 250°F (120°C) cooking surface.
For "over" eggs, the egg is partially cooked on one side, then gently flipped, and cooked on the other side until done. The egg white should be firm, and its edges should not be brown. The yolk should never be broken regardless of the degree of doneness. Not only is a broken yolk unattractive, but the spilled yolk will coagulate on contact with the hot pan, making it difficult to serve.
For over-easy eggs, the yolk should remain very runny; on a 250°F (120°C) cooking surface, the egg should cook for about 3 minutes on the first side and 2 minutes on the other. Over-medium eggs should be cooked slightly longer, until the yolk is partially set. For over-hard eggs, the yolk should be completely cooked.
Preparation
1. Select a sauté pan just large enough to accommodate the number of eggs being cooked. An 8-inch in diameter pan is appropriate for up to three eggs.
2. Add a small amount of clarified butter and heat until the fat just begins to sizzle.
3. Carefully break the eggs into the pan.
4. Continue cooking over medium-low heat until the eggs reach the appropriate degree of firmness. Sunny-side-up eggs are not flipped during cooking; "over" eggs are flipped once during cooking.
5. When done, gently flip the "over" eggs once again so that the first side is up, then gently slide the cooked eggs out of the pan onto the serving plate.
Basted eggs are a variation of sunny-side-up eggs. Basted eggs are cooked over low heat with the hot butter from the pan spooned over them as they cook. Another version of basted eggs is made by adding 1 to 2 teaspoons (5 to 10 milliliters) water to the sauté pan and then covering the pan. The steam cooks the top of the eggs.
Pan-Fried Eggs. shutterstock.com
Moist Heat Cooking
In-Shell Cooking (Simmering)
The difference between soft-cooked eggs (also called soft-boiled) and hard-cooked eggs (also called hard-boiled) is time. Both styles refer to eggs cooked in their shell in hot water. Despite the word boiled in their names, eggs cooked in the shell should never be boiled. Boiling toughens eggs and causes discoloration. Instead, the eggs should be simmered. Soft-cooked eggs are usually simmered for 3 to 5 minutes; hard-cooked eggs may be simmered for as long as 12 to 15 minutes. Sometimes it is difficult to remove the shell from very fresh eggs. Eggs that are a few days old are better for cooking in the shell.
Preparation
1. Fill a saucepan or stockpot with sufficient water to cover the eggs. Bring the water to a simmer.
2. Carefully lower each egg into the simmering water.
3. Simmer uncovered for 3 to 5 minutes (soft cooking), depending on the firmness desired.
4. Lift each egg out of the water with a slotted spoon or spider.
5. Crack the large end of the shell carefully and serve immediately.
6. When the eggs are cool enough to handle, peel them and use as desired or cover and refrigerate for up to 5 days.
Soft boiled egg. cooksillustrated.com downshiftology.com
Poaching
Eggs that are to be poached should always be very fresh. They should also be kept very cold until used, as cold egg whites stay together better when dropped into hot water. The water for poaching eggs should be held at approximately 200°F (90°C), a gentle simmer. Poached eggs should be soft and moist; the whites should be firm enough to encase the yolk completely, but the yolk should still be runny.
Some chefs add salt to the poaching water for flavor; others believe that the salt causes the egg whites to separate. To help the egg whites cling together, add 2-tablespoons (30 milliliters) white vinegar per quart (liter) of water.
Preparation
1. Fill a saucepan or stockpot with at least 3 inches (7.S centimeters) water. Add salt and vinegar if desired. Bring the water to a simmer and hold at a temperature of approximately 200°F (90°C).
2. One at a time, crack the eggs into a small ramekin or cup. If a piece of shell falls into the egg, it should be removed; if the yolk breaks, the egg can be set aside for some other use.
3. Gently slide each egg into the simmering water and cook for 3 to 5 minutes.
4. Lift the poached egg out of the water with a slotted spoon. Trim any ragged edges with a paring knife. Serve immediately.
For quantity service, eggs can be poached in advance and held for up to one day. To do so, cook the eggs as described. As each egg is removed from the hot water, set it in a hotel pan filled with ice water to stop the cooking process. The eggs can then be stored in the ice water until needed. For banquet -style service, all the eggs can be reheated at once by placing the entire pan on the stove top. Alternatively, the eggs can be reheated one or two at a time by placing them in a pan of barely simmering water until they are hot.
Poached Eggs on Toast. myrecipes.com | textbooks/workforce/Food_Production_Service_and_Culinary_Arts/Culinary_Foundations_(Cheramie_and_Thibodeaux)/10%3A_Breakfast_and_Roasting/10.01%3A_Eggs.txt |
Breakfast and Brunch
Breakfast is often an on-the-go, rushed experience; hence the popularity of breakfast sandwiches, jumbo muffins and disposable coffee cups. Brunch, on the other hand, is a leisurely experience, combining breakfast and lunch in to a social occasion. Brunch menus include traditional breakfast foods along with almost anything else. Unlike breakfast, brunch is often accompanied by champagne or other alcoholic beverages and concludes with a pastry or dessert.
New Orleans Jazz Brunch. aboveabc.com / neworleans.co
Breakfast menus typically include the following items:
• Coffee, tea or other hot beverages Fruits or fruit juices
• Eggs
• Breads, including sweet breads, Cereals, and grains
• Potatoes
• Pancakes, waffles, and French toast
• Breakfast Meats
• Bacon, breakfast sausage, smoked ham
• Dairy products, including milk, cheese and yogurt
• Although few people could sit down to a breakfast including all of these components even occasionally, most food service operations find it necessary to offer some items from each category in order to meet their customers' expectations.
The American Breakfast. tastessense.com
Beverages
Water, coffee and tea are the staples of most beverage menus. Despite their relatively low price, bottled water or a good cup of coffee or tea can be extremely important to a customer's impression of a food service operation. A cup of coffee is often either the very first or the very last item consumed by a customer. Tea, whether iced or hot, is often consumed throughout the meal. Consequently, it is important to learn to prepare and serve these beverages properly. Many varieties of water are now available and some customers prefer these specialty waters to that from the tap. Not only do these beverages complement a meal, they are important profit centers for restaurant owners. Appreciation of the proper preparation and service of these beverages is an important part of a culinary student's training.
Coffee
City roast: Also called American or brown roast, city roast is the most widely used coffee style in this country. City roast, which is medium brown in color, produces a beverage that may lack brilliance or be a bit flat, yet, it is the roast most Americans assume they prefer because it is the roast most often used in grocery store blends.
Brazilian: Somewhat darker than a city roast, Brazilian roast should begin to show a hint of dark-roast flavor. The beans should show a trace of oil. In this context, the word Brazilian has no relationship to coffee grown in Brazil.
Viennese: Also called medium-dark roast, Viennese roast generally falls somewhere between a standard city roast and French roast.
French roast: French roast, also called New Orleans or dark roast, approaches espresso in flavor without sacrificing smoothness. The beans should be the color of semisweet chocolate, with apparent oiliness on the surface.
Espresso roast: Espresso roast, also called Italian roast, is the darkest of all. The beans are roasted until they are virtually burnt. The beans should be black with a shiny, oily surface.
Tea
Black Teas
Assam: A rich black tea from northeastern India with a reddish color. It is valued by connoisseurs, especially for breakfast.
Assam tea. Flickr
Ceylon: A full-flavored black tea with a golden color and delicate fragrance. Ideal for serving iced, it does not become cloudy when cold. Darjeeling the champagne of teas, grown in the foothills of the Himalayas in northeastern India. It is a full-bodied, black tea with a Muscat flavor.
Ceylon Tea. Wikipedia
Earl Grey: blend of black teas, usually including Darjeeling, flavored with oil of bergamot. A popular choice for afternoon tea.
Twinings Earl Grey. Wikipedia
English Breakfast: An English blend of Indian and Sri Lankan black teas; it is full-bodied and robust, with a rich color.
English breakfast tea. Pricey, CC BY ND 2.0
Keemum: A mellow black Chinese tea with a strong aroma. It is less astringent than other teas and is delicious iced.
Keemum Chinese Tea. Wikipedia
Lapsang Souchong: A large -leafed (souchong) tea from the Lapsang district of China. It has a distinctive tarry, smoky flavor and aroma, appropriate for afternoon tea or dinner.
Green Teas
Green Tea: leaves & powder. Flickr
Gunpowder: A green Chinese tea with a tightly curled leaf and gray-green color. It has a pungent flavor and a light straw color. It is often served after the evening meal.
Twinings gunpowder green tea. Commons.Wikipedia.org
Sencha (common): A delicate Japanese green tea that has a light color with a pronounced aroma and a bright, grassy taste.
Sencha Tea. Wikipedia
White tea: A delicate green tea made from new buds picked before they open. Allowed to wither so that natural moisture evaporates, these leaves are lightly dried to a pale silvery color. White tea has a subtle flavor.
White Tea. Flickr
Oolong Teas
Oolong Tea. Wikipedia
Formosa Oolong: A unique and expensive large -leafed oolong tea with the flavor of ripe peaches. It is appropriate for breakfast or afternoon tea.
Formosa Oolong Tea. Wikipedia | textbooks/workforce/Food_Production_Service_and_Culinary_Arts/Culinary_Foundations_(Cheramie_and_Thibodeaux)/10%3A_Breakfast_and_Roasting/10.02%3A_Breakfast_and_Brunch.txt |
Roasting
Roasting is a cooking method that uses dry heat. Hot air envelops the food, cooking it evenly on all sides with temperatures of at least 300 °F from an open flame, oven, or other heat source. Roasting can enhance flavor through caramelization and Maillard browning on the surface of the food. Roasting uses indirect, diffused heat (as in an oven), and is suitable for slower cooking of meat in a larger, whole piece. Meats and most root and bulb vegetables can be roasted. Any piece of meat, especially red meat that has been cooked in this fashion is called a roast. Meats and vegetables prepared in this way are described as "roasted", e.g., roasted chicken or roasted squash.
Roasting Methods
For roasting, the food may be placed on a rack, in a roasting pan or, to ensure even application of heat, may be rotated on a spit or rotisserie. If a pan is used, the juice can be retained for use in gravy, Yorkshire pudding, etc. During oven roasting, hot air circulates around the meat, cooking all sides evenly. There are several plans for roasting meat in an oven: low-temperature cooking, high-temperature cooking, and a combination of both. Each method can be suitable, depending on the food and the tastes of the people.
• A low-temperature oven, 200 to 320 °F, is best when cooking with large cuts of meat, turkey and whole chickens. This is not technically roasting temperature, but it is called slow roasting. The benefit of slow roasting an item is less moisture loss and a more tender product. More of the collagen that makes meat tough is dissolved in slow cooking. At true roasting temperatures, 350 °F or more, the water inside the muscle is lost at a high rate.
• Cooking at high temperatures is beneficial if the cut is tender enough—as in filet mignon or striploin—to be finished cooking before the juices escape. A reason for high temperature roasting is to brown the outside of the food, similar to browning food in a pan before pot roasting or stewing it. Fast cooking gives more variety of flavor, because the outside is brown while the center is much less done. However, as we will see, roasting a whole chicken at 450F has its merits!
• The combination method uses high heat just at either the beginning or the end of the cooking process, with most of the cooking at a low temperature. This method produces the golden-brown texture and crust, but maintains more of the moisture than simply cooking at a high temperature, although the product will not be as moist as low-temperature cooking the whole time. Searing and then turning down to low is also beneficial when a dark crust and caramelized flavor is desired for the finished product.
In general, in either case, the meat is removed from the heat before it has finished cooking and left to sit for a few minutes, while the inside cooks further from the residual heat content, known as “carry over cooking” or “residual cooking”.
The objective in any case is to retain as much moisture as possible, while providing the texture and color. As meat cooks, the structure and especially the collagen breaks down, allowing juice to come out of the meat. Meat is juiciest at about medium rare while the juice is coming out. During roasting, meats and vegetables are frequently basted on the surface with butter, lard, or oil to reduce the loss of moisture by evaporation.
Roasting can be applied to a wide variety of meat. In general, it works best for cooking whole chickens, turkey, and leaner cuts of lamb, pork, and beef. The aim is to highlight the flavor of the meat itself rather than a sauce or stew, as it is done in braising or other moist-heat methods. Many roasts are tied with string prior to roasting. Tying holds them together during roasting, keeping any stuffing inside, and keeps the roast in a round profile, which promotes even cooking.[4]
Red meats such as beef, lamb, and venison, and certain game birds are often roasted to be "pink" or "rare", meaning that the center of the roast is still red. Roasting is a preferred method of cooking for most poultry, and certain cuts of beef, pork, or lamb. Although there is a growing fashion in some restaurants to serve "rose pork", temperature monitoring of the center of the roast is the only sure way to avoid foodborne disease.
Whole Roasted Chicken. culinarygeek.net
Prepped Beef Top Round for Roasting. Wikipedia, CCA – 3.0
Untrussed and Trussed Chicken for Roasting CCO 1.0 UPDD | textbooks/workforce/Food_Production_Service_and_Culinary_Arts/Culinary_Foundations_(Cheramie_and_Thibodeaux)/10%3A_Breakfast_and_Roasting/10.03%3A_The_Cooking_Techniques_-_Roasting.txt |
Kitchen Weight and Measures
1 pinch = 1/8 teaspoon
3 teaspoons = 1 tablespoon (teaspoon – tsp / Tablespoon = tbsp.)
2 tablespoons = 1 ounce
1 cup = 8 ounces / 16 tbsp.
¾ cup = 6 ounces / 12 tbsp.
½ cup = 4 ounces / 8 tbsp.
¼ cup = 2 ounces / 4 tbsp.
16 ounces = 1 pound
2 cups = 1 pint / 16 oz.
4 cups = 1 quart / 32 oz.
16 cups = 1 gallon / 128 oz.
2 quarts = ½ gallon / 64 oz.
4 quarts = 1 gallon
Metric Conversations
1 gram = 0.03527 oz.
1 kilogram = 2.2 pounds
28.35 grams = 1 ounce / 2 tbsp.
453.6 g. = 1 pound
5 milliliters = 1 teaspoon
15 milliliters = 1 tablespoon
240 milliliters = 1 cup
0.4732 liters = 1 pint
0.951 liters = 1 quart
1 liter = 1.06 quarts
Food Quantity Needed
(1) Number to be served X portions size = number of ounces needed
Number of ounces needed / 16 (ounces per pound) = pounds needed
EXAMPLE: 25 hamburgers, 8 oz. each. SO…. 8 oz. X 25 = 200 ounces needed. So….200oz. / 16oz (1 lb.) = 12.5 pounds of hamburger needed.
Recipe Conversion
Must know: (1) number of servings – recipe yield, and (2) # of servings needed.
• More servings than the recipe - recipe yield divided into number of servings needed is the amount needed.
• Less servings needed than the recipe yields - divide number of servings needed divided by recipe yield is the percentage to reduce the recipe by.
EXAMPLES:
(1) Recipe yields 6 servings – you need 24 servings SO… 24 / 6 = 4 times the recipe amounts.
(2) Recipe yields 24 servings and you need 6 servings So…. 6 servings / 24 servings = 25% of recipe ingredients. Or – 6/6 = 1 24/6 = 4 = ratio 1 to 4 or 25%
11.02: Measurement and Conversion Charts
Formulas for Exact Measurement
WHEN YOU KNOW: MULTIPLY BY: TO FIND:
Mass (weight) Ounces 28.35 grams
Pounds 0.45 kilograms
Grams 0.035 ounces
Kilograms 2.2 pounds
Volume (capacity) Teaspoons 5.0 milliliters
Tablespoons 15.0 milliliters
Fluid Ounces 29.57 milliliters
Cups 0.24 liters
Pints 0.47 liters
Quarts 0.95 liters
Gallons 3.785 liters
Milliliters 0.034 fluid ounces
Temperature Fahrenheit 5/9 (after subtracting 32) Celsius
Celsius 9/5 (then add 32) Fahrenheit
Rounded Measurement for Quick Reference
1 oz. = 30 g
4 oz. = 120 g
8 oz. = 240 g
16 oz. = 1 lb. = 480 g
32 oz. = 2 lb. = 960 g
36 oz. = 2¼ lb. = 1000 g (1 kg)
1/4 tsp. = 1/24 fl. oz. = 1 ml
½ tsp. = 1/12 fl. oz. = 2 ml
1 tsp. = 1/6 fl. oz. = 5 ml
1 Tbsp. = 1/2 fl. oz. = 15 ml
1 C. = 8 fl. oz. = 240 ml
2 c. (1 pt.) = 16 fl. oz. = 480 ml
4 c. (1 qt.) = 32 fl. oz. = 960 ml
4 qt. (1 gal.) = 128 fl. oz. = 3.75 It
32°F = 0°c
122°F = 50°c
212°F = 100°c
Conversion Guidelines
1 gallon 4 quarts
8 pints
16 cups (8 fluid ounces)
128 fluid ounces
1 fifth bottle approximately 1 ½ pints or exactly 26.5 fluid ounces
1 measuring cup 8 fluid ounces (a coffee cup generally holds 6 fluid ounces)
1 large egg white 1 ounce (average)
1 lemon 1 to 1 ¼ fluid ounces of juice
1 orange 3 to 3½ fluid ounces of juice
Scoop Sizes
Scoop Number Level Measure
6 2/3 cup
8 1/2 cup
10 2/5 cup
12 1/3 cup
16 1/4 cup
20 3 1/5 tablespoons
24 2 2/3 tablespoons
30 2 1/5 tablespoons
40 1 3/5 tablespoons
*The number of the scoop determines the number of servings in each quart of a mixture: for example, with a No. 16 scoop, one quart of mixture will yield 16 servings.
Ladle Size
Size Portion of a Cup Number per Quart Number per Liter
1 fl. oz. 1/8 32 34
2 fl. oz. l/4 16 17
2 2/3 fl. oz. l/3 12 13
4 fl. oz. 1/2 8 8.6
6 fl. oz. 3/4 5 1/3 5.7
Canned Goods
Size No. of Cans per Case Average Weight Average No. Cups per Can
No.¼ 1 & 2 doz. 4 oz. 1/2
No.½ 8 8 oz. 1
No. 300 1 & 2 doz. 14 oz. 1 3/4
No. 1 tall (also known as 303) 2 & 4 doz. 16 oz. 2
No. 2 2 doz. 20 oz. 2 1/2
No. 2½ 2 doz. 28 oz. 3 1/2
No.3 2 doz. 33 oz. 4
No. 3 cylinder 1 doz. 46 oz. 5 2/3
No. 5 1 doz. 3 lb. 8 oz. 5 1/2
No. 10 6 6 lb. 10 oz. 13 | textbooks/workforce/Food_Production_Service_and_Culinary_Arts/Culinary_Foundations_(Cheramie_and_Thibodeaux)/11%3A_Appendices/11.01%3A_Kitchen_Weights_and_Measurements.txt |
With-in the cooking process, there are three distinct methods in reference to applying heat to food. These are: moist heat cooking, dry heat cooking, and combination cooking
Understanding the working procedure of each of these methods, will help you to become a better, more confident and successful chef.
Moist Heat Cooking
The method of applying heat via hot liquids, associated with:
1. Poaching,
2. Simmering,
3. Boiling,
4. Blanching
5. Braising
6. Steaming
These cooking methods are most useful when a cook fully understands the relationship of time and temperature. Establishing familiarity with these aspects of the cooking process will immediately improve and enhance one’s ability in the kitchen. The moist heat cooking methods follow with regard to temperature ranges.
Poaching (160-180 degrees Fahrenheit)
Poaching: to submerge food in a hot liquid at a temperature range of 160-180 degrees Fahrenheit, I like to use the term “gentle poach”. This requires submerging food into a hot liquid of no higher than 180 degrees Fahrenheit, and can be approached by two different methods. Two approaches are applicable: place a food product in a cold liquid, slowly raising the temperature up to 170/degrees, or bring the liquid to a boil then submerge the raw food product into the hot liquid then, immediately remove it from the heat source. Either method works well to cook the product while ultimately maintaining or protecting the quality and integrity of the food. It is important to remember that all proteins coagulate when applied to heat.
Simmering & Stewing (180-205 degrees Fahrenheit)
Simmering: to submerge a food in a hot liquid within a temperature range of 180-205 degrees, representing a slow to rapid performance result. Simmering is a long and slow cooking method utilized for cooking less tender cuts of meat as in a stew. Subsequently, less tender cuts of meat are most often less expensive. When simmering at the proper temperature one has total control over the cooking process with less evaporation or controlled loss of liquid. Evaporation can be controlled by utilizing a cover on the pot or pan. Ultimately, this method allows for both maximum flavor extraction, and maximum tenderization of a protein.
Stewing: to sear off in hot fat, then simmer fully submerged in a flavored liquid (stock or broth). Stewing is considered a ‘low and slow’ cooking method, is best prepared in a cassoulet or crock- pot, and is recognized as a combination form of cookery.
Boiling (205-212 degrees Fahrenheit)
Boiling: to submerge a food in a hot liquid at a temperature range of 205-212 degrees. A true boil is not effectively reached until 212/degrees, but for convenience and better control, consider 205 – 210 a gentle boil and 210 – 212 a rapid boil.
Blanching
Blanching: to cook food quickly submerged in a hot liquid such as boiling water (212 degrees F.) or hot fat. Usually this method is followed by “shocking” a process of halting cooking by submerging the food in an ice water bath. We blanch foods for the following purposes:
• Speeds up the final cooking process
• Promotes more even and consistent cooking throughout
• Enhances color pigmentation
• Promotes vitamin and nutrient retention
• Helps to prevent spoilage/extends the shelf life of a product
• Blanched vegetables can be easier for some people to digest v/s eating raw food
• Improves flavor - cooked food can taste better than raw food
Of course, if you were blanching in hot oil as in “French fries”, one would not shock the food afterwards. The process of blanching potatoes in hot oil, removes excess liquid from the potato, prevents oxidization and yields a much crispier fried potato as a result.
Braising (275-325 degrees Fahrenheit)
Braising: meats and vegetables are seared and browned in hot fat, then simmered in a covered pot or roasting pan with a small amount of liquid. This is referred to as a
combination form of cookery. Usually, this method of cookery is reserved for less tender and less expensive cuts of meats. Eye of the round, the cut of beef commonly recommended for braising pot roast is a good example of this application or cooking method. When braising a pot roast the liquid or stock should come half way up the side of the roast. Half way through the cooking process the roast would be turned over. Braising can be done on top of the stove or in the controlled temperature environment of an oven. The latter is the preferred method. However, be sure to bring the liquid to a simmer before placing it in the oven. Long, slow cooking produces the best results with less evaporation and shrinkage. A nominal braising temperature is 300 degrees Fahrenheit for three hours. This of course depends on the cut, weight and size of the meat being braised. The oven braising temperature range is 275 to 325 degrees Fahrenheit.
Steaming (212 degrees Fahrenheit and higher)
Steaming: one of the hottest cooking mediums available ranging from 212 degrees Fahrenheit and higher. That is why pressure-cooking generally reduces overall cooking times by 2/3rds. This method is also arguably recognized and recommended for maximum vitamin and nutrient retention. Essential dietary vitamin and nutrient values are not washed away during the cooking process. As a word of caution, be very careful when cooking with steam, it is very hot and will burn if the steam is exposed to the skin or flesh of an individual. Never remove the cover of a steamer and look directly into the pot. Be sure to allow the steam to escape prior to inspecting your cooked foods.
Dry Heat Cooking
1. Roasting v/s Baking
2. Pan Roasting
3. Stove Top Smoking
4. Spit roasting
5. Grilling / Barbecuing
6. Broiling
7. Griddling
Roasting v/s Baking (300 to 400 degrees Fahrenheit)
I always ask this question on day one of my classes while discussing cooking methods. What is the difference between roasting and baking? Often, this question is followed by a long pause and then a few suggestions are offered. However, the answer is quite simple; there is no difference. Both cooking methods are performed in the temperature-controlled environment of an oven. One can low temperature roast or bake and one can high temperature roast or bake. They are both considered dry heat methods of cookery. The only difference is the semantics involved in describing a particular type of food or dish. For example, oven roasted breast of chicken verses baked chicken. Usually, the term roasting refers to meats, poultry, fish, and vegetables and baking refers more to the baking of bread or sweet and savory pastries.
Pan Roasting (350 to 450 degrees Fahrenheit)
A common cooking method frequently found on menus across America today. This method requires only a minimal amount of fat. After a food item is seared off (browned) in a hot pan on top of the stove, it is moved to a low or high temperature oven (dependent on the size of the cut) to complete the cooking process.
Stove Top Smoking (200 to 220 degrees Fahrenheit)
Is yet another dry heat cooking method. This method was traditionally carried out on a backyard BBQ or grill. Today smoking can be done on a grill or the stovetop or in an oven. However, all indoor smoking requires a good ventilation system or exhaust fan. For indoor smoking, soak wood chips in water for thirty minutes prior to using them. Drain them well, pat them dry with paper towel and then scatter them in the bottom of a roasting pan. Insert a wire rack over the wood chips, and then place your meat, fish, poultry or vegetables on the rack. Place a tightly fitting lid on the pan and secure it with aluminum foil. Begin by heating the pan on top of the stove until the wood chips start smoking. Adjust the flame or temperature to produce an even and consistent burn. At this point, the smoking procedure can be finished on top of the stove or in an oven. Due to the fact that this cooking method is so dry, it is recommended that all protein food products be marinated or brined prior to the smoking process. See Brining….
Spit roasting (minimum 300 degrees Fahrenheit)
This age-old method occurs by which a food item is skewered, and then placed on a rotisserie device over or next to an indirect flame. The advantages of using this method are uniform cooking throughout and even browning and self- basting. There is nothing more satisfying than a spit roasted chicken, marinated leg of lamb or barbecued pork loin cooked in your own back yard on a rotisserie, above a charcoal grill or a slow burning open pit wood fire…Wow! Brining is also recommended for this method of cookery.
Grilling Verses Barbecuing (350 to 400 degrees Fahrenheit)
Being from the North East this is a frequently asked question: When cooking steaks outdoors on a gas grill am I grilling or barbecuing? Why is it when inviting guests we often say; we are having a backyard barbecue this afternoon would you like to join us? Although similar, there are some very distinct differences between the two cooking methods. Traditional barbecuing is done over rendered molten coals or cindered wood ash, over long periods and best described as a long, ‘low and slow’, methodical cooking process. Thus, fattier less expensive cuts of meat are recommended for this method of cooking.
Grilling is generally cooking over high heat with charcoal, wood or gas. Items are marked or seared on the outside surface, then most often moved and finished in an oven, as not to over-char the outside surface. Alternately, move your charred foods to a rack raised above the heat source rather than directly over it. Barbecued foods are slow cooked in a low temperature oven or over slow burning coals or wood over a long period, then moved to a grill or broiler for final finishing. Barbecue sauce can be applied by brushing during the final stages of cooking - or served with on the side as an accompaniment.
Broiling (500 to 550 degrees Fahrenheit)
Can be described as a rapid high heat cooking method achieved by a direct radiant heat source from above. Typically gas or electric broiling can be a very low fat way of cooking due to the fact that very little fat or liquid is required during the cooking process. Marinated foods work well using this direct heat method. Once an item is fully cooked on one side, it is turned over to finish the process on the other side. Broiling is a clean and efficient way to accomplish Maillard enzymatic browning, the toasting of breadcrumbs or melting cheese as in “Gratinee”.
Griddling (250 to 375 degrees Fahrenheit)
Is accomplished on a flat top temperature controlled surface, referred to as a pancake griddle. The heat source is from the bottom and usually a small amount of fat or vegetable spray is required to prevent sticking. The latest trend is to use a grooved or raised griddle surface that leaves the appearance of open flame grill marks on the foods that are being prepared an in a “Panini” griddle.
Dry Heat Using Fat
1. Sautéing
2. Pan Frying
3. Deep Fat Frying
4. Pan Searing
5. Radiation or Microwaving
The only distinguishable differences between these cooking methods are the varying amounts of fat required for each. If a recipe is calling for clarified butter, it is ok to use whole butter but oil must be added to raise the smoking point of the butter. I recommend using half butter and half oil. The food product can be placed in the pan when the butter is melted and after it stops foaming.
Sautéing (350 to 400 degrees Fahrenheit)
To sauté literally means “to jump” referring to the action of the food being toss around or flipped directly in the pan. The sloped shaped sides of the pan help to facilitate this action. This method is achieved by cooking foods on very high heat in small amounts of fat. I recommend about (1-1 ½) ounces of fat in a standard 8” - 10” sauté pan. For the best results, get the pan hot, pour in the oil, followed by the food product. The most important factor when sautéing, is not to overcrowd the pan. NEVER let your proteins touch. Direct contact between proteins results in overcrowding. Overcrowding the pan causes moisture to build up, creating steam, which counteracts browning. Since browning is often the objective when sautéing, then anti-browning becomes counter-productive. Sometimes, meats are dredged in seasoned flour prior to being sautéed to help achieve uniform browning and to thicken a soup, stew, or sauce. This is perfectly acceptable; however never pre-dredge proteins ahead of time, as moisture in the product will make the flour wet and gummy.
Pan Frying or Shallow Fat Frying (325 to 400 degrees Fahrenheit)
Is accomplished is a shallow straight-sided pan with a moderate amount of fat over moderately high temperature (360) degrees. Pan-frying is recommended when preparing foods such as fish cakes, chicken parts and/or fritters. The proper amount of fat should come half way up the side of the food being fried. If too much fat is used the food product will become buoyant, preventing direct contact with the pan. Contact with the pan produces a brown exterior for which pan-frying is known. The food product is fried on one side, and then it is flipped over to finish cooking it on the other side. If the product being pan-fried is thick, dense, or on the bone, it can be finished in an oven for final cooking throughout.
Deep Fat Frying (350 to 375 degrees Fahrenheit)
This cooking method requires that foods be totally submerged in hot fat. Temperature of the fat plays a significant role in the success of deep frying foods. The average temperature range of the oil for fried foods should be between 360 - 375 degrees. It is important to regulate the temperature range of the fat throughout the cooking process or consistency of the cooked product will vary greatly. Never overcrowd the frying basket or pan because doing so will drastically
reduce the temperature of the frying oil. Recommended frying oils should have a high smoking point. Vegetable and peanut oils work well for this reason. After frying, oils should be strained, filtered and cooled before being refrigerated.
Pan Searing (400 to 450 degrees Fahrenheit)
This method utilizes the least amount fat. Using, a pre-heated hot pan, spray the surface of the pan or the food with a light coating of vegetable oil. Another option may be to utilize a previously marinated product prior to exposing it to the surface of the pan. For example, pan searing may be the method chosen to cook a marinated tuna steak. The tuna steak is removed from the marinade, quickly seared on one side and then flipped over to finish the cooking process on the other side on top of the stove. If a really thick product is used, then it can be moved to a low temperature oven to finish the cooking process to ones desired degree of doneness.
Radiation or Microwaving
Is certainly one of the greatest inventions of the 20th century. This technology has added a significant convenience to today’s modern kitchen. Small waves of radiant energy motivate the water molecules in the food to move rapidly and flow through the food at an accelerated rate creating friction, which in turn heats and cooks the food product. Thus, dried or dehydrated foods that do not contain water cannot be cooked in a microwave without being rehydrated.
As with any piece of equipment or appliance, learning how to use the microwave properly is of most importance. One of the biggest benefits of the microwave oven is its ability to speed thaw and defrost frozen foods quickly and safely. Due to the speed of the defrosting process, foods are not exposed to the “Danger Zone” for extended periods before being cooked and served. Some foods respond extremely well to the microwave cooking process, such as steamed vegetables, corn on the cob, (in the husk) and potatoes. Rotating foods during the cooking process helps to cook foods more uniformly and microwaving in multiple short blasts rather than longer uninterrupted cook times is recommended. When reheating foods, they should be covered trapping the steam and moisture for maximum efficiency.
In terms of power and heat, 700 Watts in a microwave is like cooking at 350 degrees; 800 Watts equates to 450 degrees; 900 Watts equates to 525 degrees (Self clean) 1000 Watts equates to 575 degrees; and 1100 Watts would equal 625 degrees. Note: When using a microwave to thaw food I generally recommend cooking that food item shortly after thawing it to avoid the food being exposed to the danger zone for a prolong time. Remember that microwaving cooks food from the inside out. The inside temperature of the thawed food may be warmer than the outside temperature. | textbooks/workforce/Food_Production_Service_and_Culinary_Arts/Culinary_Foundations_(Cheramie_and_Thibodeaux)/11%3A_Appendices/11.03%3A_Basic_Cooking_Methods.txt |
American Culinary Association (ACF), www.acfchefs.org
American Dietetic Association (ADA), www.eatright.org
American Hotel and Lodging Association (AHLA), www.ahla.org
American Institute of Baking (AIB), www.aibonline.org
American Institute of Wine and Food (AIWF), www.aiwf.org
American Personal Chef Association (APCA), www.personalchef.com
American Society for Healthcare Food Service Administrators (ASHFSA), www.ashfsa.org
Black Culinarian Alliance (BCA), www.blackculinarians.com
Bread Bakers Guild of America, www.bbga.org
Club Managers Association of America (CMAA), www.cmaa.org
Confrerie de la Chaine des Rotisseurs, www.chaineus.org
Dietary Managers Association (DMA), www.dmaonline.org
Foodservice Consultants Society International (FCSI), www.fcsi.org
Foodservice Educators Network International (FENI), www.feni.org
Food Truck Operation, Foodtruckoperators.com
Institute of Food Technologists (IFT), www.ift.org
International Association of Culinary Professionals (IACP), www.iacp.com
International Caterers Association, www.icacater.org
International Council of Cruise Lines, www.iccl.org
International Council on Hotel and Restaurant Institutional Education (ICHRIE), www.chrie.org
International Food Service Executives Association (IFSEA), www.ifsea.com
International Foodservice Manufacturers Association (IFMA), www.ifmaworld.com
International Inflight Food Service Association (IFSA), www.ifsanet.com
Les Dames d’Escoffier International, www.ldei.org
National Association of College and University Foodservice (NACUFS), www.nacufs.org
National Association of Foodservice Equipment Manufacturers (NAFEM), www.nafem.org
National Association for the Specialty Food Trade (NASFT), www.fancyfoodshows.com
National Food Processors Association, www.nfpa-food.org
National Ice Carving Association (NICA), www.nica.org
National Restaurant Association, www.restaurant.org
National Society for Healthcare Foodservice Management (HFM), www.hfm.org
Research Chefs Association (RCA), www.culinology.com
Retailer’s Bakery Association (RBA), www.rbanet.com
School Nutrition Association (SNA), www.schoolnutrition.org
Societe Culinaire Philanthropique, www.societeculinaire.com
Society for Foodservice Management (SFM), www.sfm-online.org
United States Personal Chef Association (USPCA), www.uspca.com
Women’s Foodservice Forum (WFF), www.womensfoodserviceforum.com
Women Chefs and Restaurateurs, www.womenfhefs.org
11.06: Industry Resources
Meats
Agri Beef www.agribeef.com/education/
American Lamb Board www.americanlamb.com/chefs-corner/curriculamb/
Butterball Foodservice www.butterballfoodservice.com
Maple Leaf Farms www.mapleleaffarms.com
National Cattlemen’s Beef Association
National Pork Board www.porkfoodservice.org
National Turkey Federation www.eatturkey.org
North American Meat Institute www.meatinstitute.org
Seafood
Alaska Seafood Marketing Institute www.alaskaseafood.org
Bureau of Seafood and Aquaculture www.freshfromflorida.com/Recipes/Seafood
National Aquaculture Association thenaa.net
Produce
American Egg Board www.aeb.org
Apricot Producers of California www.califapricot.com
Avocados from Mexico foodservice.avocadosfrommexico.com
California Cling Peach Board www.calclingpeach.com
California Cling Peach Board www.calclingpeach.com
California Avocado Commissionwww.californiaavocado.com
California Dried Plum Board www.californiadriedplums.org
California Endive www.endive.com
California Fig Advisory Board www.californiafigs.com
California Kiwifruit Commission www.kiwifruit.org
California Pear Advisory Board www.calpear.com
California Raisin Marketing Board * Dietary Tool Kit www.calraisins.org
California Strawberry Commission www.calstrawberry.com
California Table Grape Commission www.tablegrape.com
Cherry Marketing Institute www.choosecherries.com
Concord Grape Association www.concordgrape.org
Cranberry Institute www.cranberryinstitute.org
Cranberry Marketing Committee*Tool Kit www.uscranberries.com
Dole Packaged Foods *Cost Savings Calculator www.dolefoodservice.com
Florida Dept. of Citrus www.floridajuice.com
Hass Avocado Board *Tool Kit www.avocadocentral.com
Idaho Potato Commission *Cost & Sizing Guides www.idahopotato.com
Leafy Greens Council www.leafy-greens.org
Leaf Greens Marketing Association www.lgma.ca.gov/ Louisiana Sweet Potato Commission www.sweetpotato.org
Mushroom Council www.mushroomcouncil.org
National Honey Board *Teacher Guide www.honey.com
National Mango Board *Lesson Plans www.mango.org
National Onion Association*Lesson Plans www.onions-usa.org
National Processed Raspberry Council www.redrazz.org
National Watermelon Promotional Board www.watermelon.org
NC Sweet Potato Commission www.ncsweetpotatoes.com
New York Apple Association www.nyapplecountry.com
North American Blueberry Council www.blueberry.org
Northwest Cherry Growers www.nwcherries.com
Olives from Spain olivesfromspain.us/
Oregon Raspberries and Blackberries www.oregon-berries.com
Pacific Northwest Canned Pear Service www.eatcannedpears.com/
Pear Bureau Northwestwww.usapears.com
Pomegranate Council www.pomegranates.org
Potatoes USA www.PotatoGoodness.com
Produce for Better Health Foundation www.5aday.com
The Soyfoods Council www.thesoyfoodscouncil.com
U.S. Apple Association www.usapple.org
USA Rice Federation www.menurice.com
Washington Red Raspberry Commission www.red-raspberry.org
Washington State Apple Commission www.bestapples.com
Washington State Potato Commission www.potatoes.com
Wheat Foods Council *Tool kits and classroom materials www.wheatfoods.org
Wild Blueberry Assn. of North America www.wildblueberries.com
Oil, Spices and Seasonings
North American Olive Oil Association *Classroom materials www.aboutoliveoil.org
Nuts and Legumes
Almond Board of California*Tool Kit www.almonds.com/food-professionals
American Pistachio Growers www.americanpistachios.org/
California Walnut Board www.walnuts.org
National Peanut Board www.nationalpeanutboard.org
Dairy Products
Emmi Roth USA *Pairing information us.emmi.com/en
Real CA Milk www.realcaliforniamilk.com/foodservice/
Wisconsin Milk Marketing Board Pairing guides www.wisdairy.com
Specialty Foods
New York Wine & Grape Foundation www.nywine.com
Popcorn Boardwww.popcorn.org
Baking Ingredients
Guittard Chocolate Company www.guittard.com
Bay State Milling Co. www.baystatemilling.com
Manufacturing/Distributors
Barilla America www.barilla.com/en-us
Bay State Milling Co.
www.baystatemilling.com
Dole Packaged Foods *Cost Savings Calculator www.dolefoodservice.com
Knouse Foods www.knousefoodservice.com
SYSCO www.sysco.com
Unilever Food Solutions www.unileverfoodsolutions.us
Verterra Dinnerware www.verterra.com | textbooks/workforce/Food_Production_Service_and_Culinary_Arts/Culinary_Foundations_(Cheramie_and_Thibodeaux)/11%3A_Appendices/11.05%3A_Professional_Associations.txt |
Stocks
A stock is a flavored liquid. A good stock is the key to a great soup, sauce or braised dish. The French appropriately call a stock fond ("base"), as stocks are the basis for many classic and modern dishes.
Stocks were originally invented to facilitate kitchen organization and to augment integral sauces. Integral sauces are those prepared directly from the juices released by meats and fish during cooking. There are two major difficulties in preparing sauces only with the natural savory elements released in cooking. First, meats and fish rarely supply enough of their own flavorful elements to make enough savory sauce to go around. Second, in a restaurant setting, it is difficult and impractical to prepare an integral sauce for each dish. Because of these problems, chefs developed stocks, which can be made from less-expensive cuts of meat, inexpensive meat trimmings, and bones.
The first stocks were simple broths, by-products of poached meat and fish dishes. Before the method of preparing stocks was refined and systematized, meat was often braised or roasted with a thick slice of ham or veal to give extra body to the sauce.
The challenge to the chef is to get the maximum flavor into a stock with a minimum of expense. A stock made with a large proportion of meat that is then carefully reduced to a light glace will have a magnificent flavor but will be too expensive for most restaurants. For this reason, many chefs have replaced much of the meat in older stock recipes with bones. Although bones can supply gelatin and a minimal amount of savor to a stock, a stock made with bones will never have the depth and flavor of one made with meat.
There are several types of stocks. Although they are all made from a combination of bones, vegetables, seasonings and liquids, each type uses specific procedures to give it distinctive character.
A white stock is made by simmering chicken, veal or beef bones in water with vegetables and seasonings. The stock remains relatively colorless during the cooking process.
A brown stock is made from chicken, veal, beef, or game bones and vegetables, all of which are caramelized before being simmered in water with seasonings. The stock has a rich, dark color.
Both a fish stock and a fumet are made by slowly cooking fish bones, or crustacean shells, and vegetables, without coloring them, then simmering them in water with seasonings for a short time. For a fumet, wine and lemon juice are also added. The resulting stock or fumet is a strongly flavored, relatively colorless liquid.
A court bouillon is made by simmering vegetables and seasonings in water and an acidic liquid such as vinegar or wine. It is used to poach fish or vegetables. The quality of a stock is judged by four characteristics: body, flavor, clarity and color. Body develops when collagen proteins dissolve in protein - based stock. Vegetable stocks have less body than meat stocks because they lack animal p rote in. Flavoring vegetables such as mirepoix: herb sachets and the proper ratios of ingredients to liquid give stocks their flavor. Clarity is achieved by removing impurities during stock making. Any ingredients contribute to a stock's color. Vegetables such as leeks and carrots give white stock a light color. Browned bones and tomato paste provide color to dark stocks. Improper uses of coloring ingredients can overwhelm the color and flavor of a stock.
The term jus traditionally describes the light, natural liquid derived from the drippings of a roast. Because a natural jus is perhaps the most satisfying and flavorful of all sauces, chefs use a variety of techniques to simulate the flavor of a natural jus, using meat trimmings and bones. To prepare a stock with some of the full, natural flavor of a jus, meat trimmings are usually browned and cooked for a short time with a previously made full-flavored stock.
Classic demi-glace is a stock that has been reduced and bound with starch until it has the consistency of a very light syrup or glace. Classic demi-glace is the basis for classic brown sauces. Natural demi-glace, also called coulis, is thickened by reduction or continual remoistening with additional meat; no starch is used in its preparation.
Glaces are stocks that have been slowly cooked down (reduced) to a thick syrup. These are convenient to have on hand in professional kitchens because they keep well and can be added to sauces at the last minute to give a richer flavor, a deeper color, and a smoother texture. Some chefs rely almost entirely on meat glace (glace de viande) for preparing brown sauces.
Essences are extracts made from vegetables and used as last-minute flavorings for sauces; an essence is to a vegetable what a jus is to meat or fish. In classic sauce making, essences are usually used as a final flavoring for more complex stockbased sauces. In most of these situations, essences can be dispensed with and the ingredient itself simply infused in the sauce and strained out at the last minute.
Stocks were originally invented to facilitate kitchen organization and to augment integral sauces. Integral sauces are those prepared directly from the juices that are released by meats and fish during cooking. There are two major difficulties in preparing sauces only with the natural savory elements released in cooking. First, meats and fish rarely supply enough of their own flavorful elements to make enough savory sauce to go around. Second, in a restaurant setting, it is difficult and impractical to prepare an integral sauce for each dish. Because of these problems, chefs developed stocks, which can be made from less-expensive cuts of meat, inexpensive meat trimmings, and bones.
The obvious method for supplying additional savory meat juices or drippings is to prepare extra meat; for example, roast two turkeys to make enough full-flavored gravy for one. This was common in French cooking until the eighteenth century: Extra jus was prepared by roasting meat and squeezing out the juices in a press.
The first stocks were simple broths, by-products of poached meat and fish dishes. Before the method of preparing stocks was refined and systematized, meat was often braised or roasted with a thick slice of ham or veal to give extra body to the sauce.
The challenge to the chef is to get the maximum flavor into a stock with a minimum of expense. A stock made with a large proportion of meat that is then carefully reduced to a light glace will have a magnificent flavor but will be too expensive for most restaurants. For this reason, many chefs have replaced much of the meat in older stock recipes with bones. Although bones can supply gelatin and a minimal amount of savor to a stock, a stock made with bones will never have the depth and flavor of one made with meat.
Much of the expense of using meat in a stock can be defrayed by saving the cooked meat for another use, either to serve in the restaurant or to the staff. Boiled beef can, for instance, be made into excellent salads (with capers, pickles, vinaigrette), into a salade bouchere (made with diced boiled beef, hard-boiled eggs, potatoes, tomatoes, and chopped parsley), and into ravioli filling (seasoned, chopped with a little beef marrow). It can also be reheated in tomato sauce, or cooked in a miroton (baked into a kind of gratin with stewed onions, breadcrumbs, and a little vinegar) with potatoes (hachis parmentier- the meat is minced, covered with mashed potatoes and baked).
Traditional stock recipes divide into white and brown. White stocks are usually prepared by first blanching meat and bones and then moistening them with cold water. Brown stocks are prepared by first browning the meats or bones, either in the oven or on top of the stove. Most of the recipes in this book that use stock call for brown stocks, mainly because they have a richer, more complex flavor.
Improving a Stock's Flavor
Prepare Double and Triple Stocks. Stocks can always be improved by using an already prepared stock to moisten meats for a new batch. When the moistening liquid for a stock is an already prepared stock, the result is called a double stock. If a double stock is in turn used to moisten more meat, the result is a triple stock. The elaborate stocks of the eighteenth and nineteenth centuries were made using this method of continuous remoistening with progressively richer and richer stock to prepare coulis and essences.
Making double and triple stocks is expensive. Most methods for making stock are designed to imitate double and triple stocks without the expense. If, however, the chef can defray the cost of the ingredients so that double and triple stocks made with meat can be used for sauce making, the resulting sauces will have an inimitable depth, complexity, and savor.
Caramelize the Ingredients. Stocks can be given heightened color and flavor by first caramelizing the meat juices on the bottom of the pan before the final moistening with water or stock. Precooking the ingredients in this way will also result in a clearer stock.
Add Gelatinous Cuts. Some recipes call for the addition of a veal foot (split and blanched starting in cold water) or strips of pork rind to stocks. These ingredients contribute gelatin and give the stock a smoother, richer texture
Balance the Ingredients. The final decision as to how stocks will be prepared depends on the kitchen's cooking style and budget. The chef will have to rely on experience and expertise to balance the components in the stock to derive the best flavor from the ingredients. If a stock is to be radically reduced for sauce making or if double or triple stocks are being prepared, the chef must determine whether additional vegetables and a second or third bouquet garni are needed. If too many vegetables are added to the preliminary stock or if additional vegetables are added at each stage in the preparation of a double or triple stock, the natural sugars in the vegetables may become too concentrated, and the stock will be too sweet. You may find that as the stock nears completion, one of the vegetables or one of the herbs in the bouquet garni is too assertive; decrease the amount of that ingredient the next time you make the stock.
If a finished stock tastes flat, its flavor can be improved by adding a fresh bouquet garni and some freshly sweated mirepoix vegetables. Whether or not this is necessary depends on how the stock will be used.
PROPER AND IMPROPER PROCEDURES
1. Always moisten stock with cold liquid. If hot water is added to meat, it causes the meat to release soluble proteins (albumin) quickly into the surrounding liquid. These proteins immediately coagulate into very fine particles and cloud the stock. When cold liquid is used and slowly heated, the proteins contained in the meat (or fish) coagulate in larger clumps and float to the top, where they can be skimmed. When adding liquid to an already simmering stock to compensate for evaporation, make sure it is cold.
2. Never allow a stock to boil. As meat and bones cook, they release proteins and fats into the surrounding liquid. Stock should be heated slowly to only a simmer. At a slow simmer, these components appear as scum on top of the stock and can be skimmed. If the stock is boiling, these substances are churned back into the stock and become emulsified. The resulting stock is cloudy and has a dull, muddy, greasy flavor, which will only worsen if the stock is reduced (or bound) for a sauce. When the stock comes to a simmer skim it every 5 to 10 minutes for the first hour with a ladle to prevent fat and scum from working their way back into the stock. As the stock cooks, it needs to be skimmed only every 30 minutes to an hour. Keep the ladle in a container of cold water next to the pot so it is convenient for skimming and so that it does not become caked with fat and scum.
3. Do not use too much liquid. The higher the proportion of solid ingredients to liquid, the more flavorful the stock will be. Many beginning cooks completely cover the solid ingredients with liquid at the beginning of cooking. Because the solid ingredients in a stock settle during cooking, the cook often finds that he or she has added more liquid than necessary and the resulting stock is thin. It is best to use only enough liquid or stock to come three-quarters of the way to the top of the ingredients. The only exceptions to this rule are stocks with extremely long cooking times, where any excess liquid will evaporate anyway.
4. Do not move the contents of the stock during cooking and straining. As stock cooks, albumin and other solids settle along the bottom and sides of the pot. If the stock is disturbed, these solids will break up and cloud the stock. When straining the finished stock, do not press on the ingredients in the strainer; allow enough time for the liquid to drain naturally.
5. Do not over-reduce. Stocks are often reduced to concentrate their flavor and to give them an appetizing, light, syrupy texture. Although reduction is an almost essential technique for converting stocks into sauces, much of the delicacy and flavor of meats is lost if reduced for too long. Many of the flavors contained in stock are aromatic and evaporate when simmered over a pro, longed period, leaving a flat taste. Highly reduced stocks often contain a large concentration of gelatin, which gives them a sticky feeling and texture in the mouth.
6. It is preferable to prepare a double or triple stock rather than to try to reduce a stock to intensify its flavor. The expense will be the same per given quantity of finished stock.
7. Do not add the liaison until all the fat and scum have been carefully skimmed. Traditional recipes often suggest adding a thickener, such as roux, cornstarch, or arrowroot, to stock to thicken it lightly and give it texture. Once starch is added to a stock, any fat emulsified in the liquid will be held in solution by the starch and will become difficult to skim.
8. Store stocks carefully. Warm stock is a perfect medium for bacteria (beef broth was originally used to line petri dishes in laboratories). Avoid keeping stocks between 40° and 140°F (5° and 60°C) for long periods. The danger of spoilage increases in hot weather and when larger amounts of stock are being prepared. A quart or two of stock can be allowed to cool at room temperature before it is refrigerated with little danger of spoilage. Larger amounts of stock are best cooled by floating a container (make sure the bottom is well scrubbed) of ice in the stock to chill it before refrigerating. Large amounts of stock may require several batches of ice.
Ingredients
The basic ingredients of any stock are bones, a vegetable mixture known as a mirepoix, seasonings and water.
Bones
Bones are the most important ingredient; they add flavor, richness and color to the stock. Traditionally, the kitchen or butcher shop saved the clay's bones to make stock. Because many meals and poultry items are now purchased precut, or portioned, food service operations often purchase bones specifically for stock making.
Different bones release their flavor at different rates. Even though the bones are cut into 3- to 4-inch (8- to 10-centimeter) pieces, a stock made entirely of beef and/ or veal bones requires six to eight hours of cooking time, while a stock made entirely from chicken bones requires only five to six hours.
Beef and Veal Bones
The best bones for beef and veal stock come from the younger animals. They contain a higher percentage of cartilage and other connective tissue than do bones from more mature animals. Connective tissue has a high collagen content. Through the cooking process, the collagen is converted into gelatin and water. The gelatin adds richness and body to the finished stock. The best beef and veal bones are back, neck and shank bones, as they have high collagen contents. Beef and veal bones should be cut with a meat saw into small pieces, approximately 3 to 4 inches (8 to 10 centimeters) long, so that they can release as much flavor as possible while the stock cooks.
Chicken Bones
The best bones for chicken stock are from the neck and back. If a whole chicken carcass is used, it can be cut up for easier handling.
Fish Bones
The best bones for fish stock are from lean fish such as sole, flounder, whiting or turbot. Bones from fatty fish (for example, salmon, tuna and swordfish) do not produce good stock because of their high fat content and distinctive flavors. The entire fish carcass can be used, but it should be cut up with a cleaver or heavy knife for easy handling and even extraction of flavors. After cutting, the pieces should be rinsed in cold-water to remove blood, loose scales and other impurities.
Other Bones
Lamb, turkey, game and ham bones can also be used for white or brown stocks. Although mixing bones is gene rally acceptable, be careful of blending strongly flavored bones, such as those from lamb or game, with beef, veal or chicken bones. The former's strong flavors may not be appropriate or desirable in the finished product.
Mirepoix
A mirepoix is a mixture of onions, carrots and celery added to a stock to enhance its flavor and aroma. Although chefs differ on the ratio of vegetables, generally a mixture of 50 percent onions, 25 percent carrots and 25 percent celery, by weight, is used. For a brown stock, onionskins may be used to add color. It is not necessa1y to peel the carrots or celery because flavor, not aesthetics, is important.
The size of the mirepoix ‘chop’ is determined by the stock's cooking time: The shorter the cooking time, the smaller the vegetables must be chopped to ensure that all possible flavor is extracted. For white or brown stocks made from beef or veal bones, the vegetables should be coarsely chopped into large, 1- to 2-inch (2.5- to 5-centimeter) pieces. For chicken and fish stocks, the vegetables should be more finely chopped into 1/2-inch (1.2-centimeter) pieces.
White Mirepoix. A white mirepoix is made by replacing the carrots in a standard mirepoix with parsnips and adding mushrooms and leeks. Some chefs prefer to use a white mirepoix when making a white stock, as it produces a lighter product. Sometimes parsnips, mushrooms and leeks arc added to a standard mirepoix for additional flavors.
Seasonings
Principal stock seasonings are peppercorns, bay leaves, thyme, parsley stems and, optionally, garlic. These seasonings generally can be left whole. A stock is cooked long enough for all of their flavors to be extracted so there is no reason to chop or grind them. Seasonings generally are added to the stock at the start of cooking. Some chefs do not acid seasonings to beef or veal stock until midway through the cooking process, however, because of the extended cooking times. Seasonings can be added as a sachet d'epices, or a bouquet garni.
Salt. Salt, an otherwise important seasoning, is not added to stock. Because a stock has a variety of uses, it is impossible for the chef to know how much salt to acid when preparing it. If, for example, the stock was seasoned to taste with salt, the chef could not reduce it later; salt is not lost through reduction, and the concentrated product would taste too salty. Similarly, seasoning the stock to taste with salt could prevent the chef from adding other ingredients that are high in salt when finishing a recipe. Unlike many seasonings whose flavors must be incorporated into a product through lengthy cooking periods, salt can be added any time during the cooking process with the same effect.
Principles of Stock Making
The following principles apply to all stocks. You should follow them in order to achieve the highest-quality stocks possible.
• Start the stock in cold water.
• Simmer the stock gently.
• Skim the stock frequently.
• Strain the stock carefully.
• Cool the stock quickly.
• Store the stock properly.
• Degrease the stock.
Start the Stock in Cold Water
The ingredients should always be covered with cold water. When bones are covered with cold water, blood and other impurities dissolve. As the water heats, the impurities coagulate and rise to the surface, where they can be removed easily by skimming. If the bones were covered with hot water, the impurities would coagulate more quickly and remain dispersed in the stock without rising to the surface, making the stock cloudy.
If the water falls below the bones during cooking, add water to cover them. Flavor cannot be extracted from bones not under water, and bones exposed to the air will darken and discolor a white stock.
Simmer the Stock Gently
The stock should be brought to a boil and then reduced to a simmer, a temperature of approximately 185°F (85°C). While simmering, the ingredients release their flavors into the liquid. If kept at a simmer, the liquid will remain clear as it reduces and the stock develops. Never boil a stock for any length of time. Rapid boiling of a stock, even for a few minutes, causes impurities and fats to blend with the liquid, making it cloudy.
Skim the Stock Frequently
A stock should be skimmed often to remove the fat and impurities that rise to the surface during cooking. If they are not removed, they may make the stock cloudy.
Strain the Stock Carefully
Once a stock finishes cooking, the liquid must be separated from the bones, vegetables and other solid ingredients. In order to keep the liquid clear, it is important not to disturb the solid ingredients when removing the liquid. This is easily accomplished if the stock is cooked in a steam kettle or stockpot with a spigot at the bottom.
If the stock is cooked in a standard stockpot, to strain it:
• Skim as much fat and as many impurities from the surface as possible before removing the stockpot from the heat.
• After removing the pot from the heat, carefully ladle the stock from the pot without stirring it.
• Strain the stock through a china cap lined with several layers of cheesecloth.
Cool the Stock Quickly
Most stocks are prepared in large quantities, cooled and held for later use. Great care must be taken when cooling a stock to prevent food-borne illnesses or souring. To cool a stock below the temperature danger zone quickly and safely:
• Keep the stock in a metal container. A plastic container insulates the stock and delays cooling.
• Vent the stockpot in an empty sink by placing it on blocks or a rack. This allows water to circulate on all sides and below the pot when the sink is filled with water.
• Install an overflow pipe in the drain and fill the sink with cold water or a combination of cold water and ice. Make sure that the weight of the stockpot is adequate to keep it from tipping over.
• Let cold water run into the sink and drain out the overflow pipe. Stir the stock frequently to facilitate even, quick cooling.
Ice Paddles. In addition to this venting procedure, cooling wands can be used to speed the cooling of stocks, soups, sauces and other liquids. These wands (also known as ice paddles) are hollow plastic containers that can be filled with water or ice, sealed, and then used to stir and cool liquids. Clean and sanitize the wand after each use to prevent cross-contamination.
Cooling and Handling Stocks (SAFETY). A two-stage cooling method is recommended for keeping stock out of the temperature danger zone. First, cool the stock to 70°F (21°C) within 2 hours and from 70°F to below 41°F (21°F to below 5°C) in an additional 4 hours, for a total of 6 hours. To prevent bacterial growth if these temperatures have not been met, the stock must be reheated to 165°F (74°C) for 15 seconds within 2 hours.
Store the Stock Properly
Once the stock is cooled, transfer it to a sanitized covered container (either plastic or metal) and store it in the refrigerator. As the stock chills, fat rises to its surface and solidifies. If left intact, this layer of fat helps preserve the stock. Stocks can be stored for up to one week under refrigeration or frozen for several months.
Degrease the Stock
Degreasing a stock is simple: When a stock is refrigerated, fat rises to its surface, hardens and is easily lifted or scraped away before the stock is reheated.
White Stock
A white or neutral stock may be made from beef, veal or chicken bones. The finished stock should have a good flavor, good clarity, high gelatin content and little or no color. Veal bones are most often used, but any combination of beef, veal or chicken bones may be used.
Blanching Bones
Chefs disagree on whether the bones for a white stock should be blanched to remove impurities. Some chefs argue that blanching keeps the stock as clear and colorless as possible; others argue that blanching removes nutrients and flavor.
Procedure for Blanching Bones
1. If you choose to blanch the bones:
2. Wash the cut-up bones, place them in a stockpot and cover them with cold water.
3. Bring the water to a boil over high heat.
4. As soon as the water boils, skim the rising impurities. Drain the water from the hones and discard it.
5. Refill the pot with cold water, and proceed with the stock recipe.
White Stock (8:1 Ratio)
Mise en Place
• Cut up and wash bones.
• Peel and chop onions, carrots and celery for mirepoix.
• Prepare herb sachet.
Yield: 2 gal. (8 Liters)
• Bones, veal, chicken or beef 16 lb. (7 kg)
• Cold water, 3 gal. (11 lt)
• Mirepoix, 2 lb. (l kg)
Sachet
• Bay leaves, 2 (2)
• Dried thyme, ½ tsp. (2 ml)
• Peppercorns, crushed ½ tsp. (2 ml)
• Parsley stems, 8 (8)
1. Cut the washed bones into pieces approximately 3-4 inches (8-10 centimeters) long.
2. Place the bones in a stockpot and cover the m with cold water. If blanching, bring the water to a boil, skimming off the scum that rise s to the surface. Drain off the water and the impurities. Then add the 3 gallons (11 liters) cold water and bring to a boil. Reduce to a simmer.
3. If not blanching the bones, bring the cold water to a boil. Reduce to a simmer and skim the scum that forms.
4. Add the mirepoix and sachet to the simmering stock.
5. Continue simmering and skimming the stock for 6 to 8 hours. (If only chicken bones are used, simmer for 3 to 4 hours.)
6. Strain, cool and refrigerate.
Brown Stock
Brown chicken stock is especially useful in kitchens where it is not practical to prepare meat glaces and beef stocks regularly. If the kitchen does not generate enough chicken carcasses for the stock, most wholesale butchers will deliver chicken carcasses at a nominal cost. Stewing hens can also be added to the stock for a fuller flavor, but this of course increases the stock's cost.
Brown chicken stock can be used for deglazing sauté pans and roasting pans and as a base for more concentrated, specialized stocks, such as game or pigeon. It is good to have brown chicken stock on hand to use as a thinner for sauces that may have become too reduced.
Brown Veal Stock. Roast all the ingredients for white veal stock, except the bouquet garni and water, in a 400°F (200°C) oven. Turn the meat, bones, and vegetables from time to time until they are evenly browned. Avoid burning any of the ingredients or letting the juices burn on the bottom of the roasting pan. Transfer the ingredients to a stockpot and add the bouquet garni. Deglaze the roasting pan with water. When all the juices have dissolved, add the deglazing liquid to the ingredients in the stockpot. Moisten, cook, and strain the stock as for white veal stock.
Mise en Place for a Brown Stock
• Cut up and wash bones.
• Peel and chop onions, carrots and celery for mirepoix.
• Prepare herb sachet.
A brown stock is made from chicken, veal, beef or game bones. The finished stock should have a good flavor, rich dark brown color, good body and high gelatin content. The primary differences between a brown stock and a white stock are that for a brown stock, the bones and mirepoix are caramelized before being simmered and a tomato product is added. These extra steps provide the finished stock with a rich dark color and a more intense flavor.
Caramelizing
Caramelization is the process of browning the sugars found on the surface of most foods. This gives the stock its characteristic flavor and color.
Procedure for Caramelizing Bones
For caramelizing, do not wash or blanch the bones as this retards browning. To caramelize:
1. Place the cut-up bones in a roasting pan one layer deep. It is better to roast several pans of bones than to overfill one pan.
2. Roast the bones for approximately 1 hour in a hot oven (375°F/190°C). Stirring occasionally, brown the bones thoroughly, but do not allow them to burn.
3. Transfer the roasted bones from the pan to the stockpot.
Deglazing the Pan
After the bones are caramelized, the excess fat should be removed and reserved for future use. The caramelized and coagulated proteins remaining in the roasting pan are very flavorful. To utilize them, deglaze the pan.
Procedure for Deglazing the Pan
1. Place the pan on the stove over medium heat, and add enough water to cover the bottom of the pan approximately '12 inch (1.2 centimeters) deep.
2. Stir and scrape the pan bottom to dissolve and remove all the caramelized materials while the water heats.
3. Pour the deglazing liquid (also known as the deglazing liquor) over the bones in the stockpot.
Procedure for Caramelizing Mirepoix
1. Add a little of the reserved fat from the roasted bones to the roasting pan after it has been deglazed. (Alternatively, use a pan large enough to contain all the mirepoix comfortably.)
2. Sauté the mirepoix, browning all the vegetables well and evenly without burning them.
3. Add the caramelized mirepoix to the stockpot.
4. Almost any tomato product can be used in a brown stock: fresh tomatoes, canned whole tomatoes, crushed tomatoes, tomato puree or paste. If using a concentrated tomato product such as paste or puree, use approximately half the amount by weight of fresh or canned tomatoes. The tomato product should be added to the stockpot when the mirepoix is added.
Brown Stock Recipe
• Bones, veal, chicken or beef 15 lb. (7 kg)
• Cold water, 3 gal. (11 lt)
• Mirepoix, 2 lb. (l kg)
Sachet
• Bay leaves, 2 (2)
• Dried thyme, ½ tsp. (2 ml)
• Peppercorns, crushed ½ tsp. (2 ml)
• Garlic cloves, crushed 3 (3)
• Parsley stems, 8 (8)
1. Place the bones in a roasting pan, in one layer and brown in a 375°F (190°) oven. Turn the bones occasionally to brown them evenly.
2. Remove the bones and place them in a stockpot. Pour off the fat from the roasting pan and reserve it.
3. Deglaze the roasting pan with part of the cold water.
4. Add the deglazing liquor and the rest of the cold water to the bones, covering them completely. Bring to a boil and reduce to a simmer.
5. Add a portion of the reserved fat to the roasting pan and sauté the mirepoix until evenly browned. Then add it to the simmering stock.
6. Add the tomato paste and sachet to the stock and continue to simmer for 6 to 8 hours, skimming as necessary.
7. Strain, cool and refrigerate.
Fish Stock and Fish Fumet
A fish stock and a fish fumet are similar and can be used interchangeably in most recipes. Both are clear with a pronounced fish flavor and very light body. A fumet, however, is more strongly flavored and aromatic and contains an acidic ingredient such as white wine and / or lemon juice. Only the bones and heads of lean fish and crustacean shells are used to make fish stock. Oily fish such as mackerel, salmon or tuna are not used as their pronounced flavor would overwhelm the stock.
The fish bones and shells used to make a fish stock or fumet should be washed but never blanched because blanching removes too much flavor. They may be sweated without browning if desired, however. Because of the size and structure of fish bones and crustacean shells, stocks and fumets made from them require much less cooking time than even a chicken stock; 30 to 45 minutes is usually sufficient to extract full flavor. Mirepoix or other vegetables should be cut small so that all of their flavors can be extracted during the short cooking time. The procedure for making a fish stock is very similar to that for making a white stock.
Commercial Bases
Commercially produced flavor (or convenience) bases are widely used in food service operations. They are powdered or paste flavorings added to water to create stocks or, when used in smaller amounts, to enhance the flavor of sauces and soups. These products are also sold as bouillon cubes or granules. Although inferior to well-made stocks, flavor bases do reduce the labor involved in the production of stocks, sauces and soups. Used properly, they also ensure a consistent product. Because bases do not contain gelatin, stocks and sauces made from them do not benefit from reduction. Bases vary greatly in quality and price.
Sodium (salt) is the main ingredient in many bases. Better bases are made primarily of meat, poultry or fish extracts. To judge the quality of a flavor base, prepare it according to package directions and compare the flavor to that of a well-made stock. The flavor base can be improved by adding a mirepoix, standard sachet and a few appropriate bones to the mixture, then simmering for one or two hours. It can then be strained, stored and used like a regular stock. Although convenience bases are widely used in the industry, it is important to remember that even the best base is a poor substitute for a well-made stock.
Fish Stock
Mise en Place
• Wash fish bones or shells.
• Peel and chop onions, carrots celery for mirepoix.
• Prepare herb sachet.
Yield: 1 gal. (4 It)
• Mirepoix, small dice, 1 lb. (450 g)
• Mushroom trimmings, 8 oz. (250 g)
• Clarified butte,r 2 fl. oz. (60ml)
• Fish bones or crustacean shells, 8 lb. (4.5 kg)
• Water, 5 qt. (5 lt)
Sachet
• Bay leaves, 2 (2)
• Dried thyme ½ tsp. (2 ml)
• Peppercorns, crushed ¼ tsp. (1 ml)
• Parsley stems, 8 (8)
1. Sweat mirepoix and mushroom trimmings in butter until tender for 1 to 2 minutes.
2. Combine all ingredients except the sachet in a stockpot.
3. Bring to a simmer and skim impurities as necessary.
4. Add the sachet and simmer uncovered for 30 to 45 minutes.
5. Strain, cool and refrigerate.
Fish Fumet
Mise en Place
• Peel onion and chop into small dice.
• Cut up and wash bones.
Yield: 2 gal. (8 Lt)
• Whole butter, 2 oz. (60 g)
• Onions, small dice 1 lb. (500 g)
• Parsley stems, 12 (12)
• Fish bones, 10 lb. (5 kg)
• Dry white wine, 1½ pt. (750 ml)
• Lemon juice, 2 fl. oz. (60 ml)
• Cold water or fish stock, 7 qt. (7 lt)
• Mushroom trimmings, 2 oz. (60 g)
• Fresh thyme ,1 sprig (1 sprig)
• Lemon slices, 10 (10)
1. Melt the butter in a stockpot.
2. Add the onion, parsley stems and fish bones. Cover the pot and sweat the bones over low heat.
3. Sprinkle the bones with the wine and lemon juice.
4. Add the cold water or stock, mushroom trimmings, thyme and lemon slices. Bring to a boil, reduce to a simmer and cook approximately 30 minutes, skimming frequently.
5. Strain, cool and refrigerate.
Vegetable Stock
A good vegetable stock should be clear and light-colored. Because no animal products are used, it has no gelatin content and little body. A vegetable stock can be used instead of a meat-based stock in most recipes. This substitution is useful when preparing vegetarian dishes or as a lighter, more healthful alternative when preparing sauces and soups. Although almost any combination of vegetables can be used for stock making, more variety is not always better.
Sometimes a vegetable stock made with one or two vegetables that complement the finished dish particularly well will produce better results than a stock made with many vegetables. Strongly favored vegetables such as asparagus, broccoli and other cruciferous vegetables, spinach and bitter greens, for example, should be avoided when making an all-purpose vegetable stock. Potatoes and other starchy vegetables will cloud the stock and should not be used unless clarity is not a concern.
Vegetable stock can be used to impart a lightness and a delicate aromatic flavor to sauces. In traditional cooking, it was primarily used as a poaching liquid for fish and sometimes calves' brains. Contemporary chefs are using it more frequently in sauce making because of its delicacy, freshness, and ease of preparation. Vegetable stock can also be used instead of water for steaming fish, meats, or vegetables. It is often an excellent substitute for fish stock when good -quality fresh fish or fish bones are unavailable.
Vegetable Stock Recipe
Mise en Place
• Peel and chop onions, carrots and celery for mirepoix.
• Clean, peel and chop leeks, garlic cloves, fennel and turnip.
• Wash and dice tomato. Prepare herb sachet.
Yield: l gal. (4 lt)
• Vegetable oil, 2 fl. oz. (60 ml)
• Mirepoix, small dice 1 lb. (900 g)
• Leek, whites and greens, chopped 8 oz. (250 g)
• Garlic cloves, chopped 4 (4)
• Fennel, small dice 4 oz. (120 g)
• Turnip, diced 2 oz. (60 g)
• Tomato, diced 2 oz. (60 g)
• White wine, 8 fl. oz. (250 ml)
• Water, 1 gal. (4 lt)
Sachet
• Bay leaf 1 (1)
• Dried thyme ½ tsp. (2 ml)
• Peppercorns, crushed ¼ tsp. (1 ml)
• Parsley stems 8 (8)
1. Heat the oil. Add the vegetables and sweat for 10 minutes.
2. Add the wine, water and sachet.
3. Bring the mixture to a boil, reduce to a simmer and cook for 45 minutes.
4. Strain, cool and refrigerate.
Court Bouillon
A court bouillon though not actually a stock, is prepared in much the same manner as stocks, so it is included here. A court bouillon (French for "short broth ") is a flavored liquid, usually water and wine or vinegar, in which vegetables and seasonings have been simmered to impart their flavors and aromas.
Although the terms court bouillon and nage are often used interchangeably, court bouillon describes a broth from which the vegetables have been strained, whereas a nage is used for serving fish and shellfish a la nage - a style of presentation in which the fish is served surrounded by the poaching liquid containing the vegetables cut in to decorative shapes.
The technique for preparing court bouillon depends on whether the chef wants the vegetables to release all their flavor into the surrounding liquid or prefers them to retain some of their flavor and texture (as in the preparation a la nage). To get the vegetables to release the most flavor into the surrounding liquid, they are best sweated in a small amount of butter before being moistened. They should then be cooked in water alone for at least 15 minutes before any wine or vinegar is added- the acidity in both these liquids prevents the vegetables from cooking completely. When preparing a nage, where the vegetables will be served as an accompaniment, bring the wine and water to a simmer and slide in the chopped and sliced vegetables. There are no hard and fast rules for which and how many vegetables should go into the stock.
This decision depends largely on the final use of the stock. It is practically impossible to add too many onions, leek greens, or fennel, whereas too many carrots can make the stock too sweet, especially if it is going to be reduced for a sauce. The following recipe suggests the usual bouquet gami ingredients, but these too can be altered to give the stock a personal or regional character.
Full-flavored herbs, such as oregano, marjoram, or lavender, should generally be avoided except under special circumstances, for example, for grilled fish surrounded by a court-bouillon -based sauce or steamed crustaceans. Although traditional recipes call for a standard combination of vegetables to arrive at an anonymously flavored vegetable stock, contemporary chefs often prepare court bouillon using only one or two vegetables to give a sauce a particular, subtle flavor. Court bouillon made with leeks or fennel alone will give a delicate yet pronounced character to a sauce. Salt should be added to a vegetable stock only if it is to be used as is, without reduction. If using vegetable stock as an accompaniment to fish or meats cooked a la nage, the vegetables should be cut carefully and evenly. Vegetable stock is best used the day it is made.
• Court bouillon is most commonly used to ‘poach’ foods such as fish and shellfish. Recipes vary depending on the foods to be poached. Although a court bouillon can be made in advance and refrigerated for later use, its simplicity lends itself to fresh preparation whenever needed.
Court Bouillon Recipe
Mise en Place
• Peel and chop onions, carrots and celery for mirepoix.
• Crush peppercorns.
Yield: 1 gal. (4 lt)
• Water, 1 gal. (4 lt)
• Vinegar, 6 fl. oz. (180 ml)
• Lemon juice, 2 fl. oz. (60 ml)
• Mirepoix, 1 lb. 6 oz. (650 g)
• Bay leaves, 4 (4)
• Peppercorns, crushed 1 tsp. (8 ml)
• Dried thyme, 1 pinch (1 pinch)
• Parsley stems, 1 bunch (1 bunch)
Nage
An aromatic court bouillon is sometimes served as a light sauce or broth with fish or shellfish. This is known as a nage, and dishes served in this manner are described as a la nage (French for "swimming"). After the fish or shellfish is cooked, additional herbs and aromatic vegetables are added to the cooking liquid, which is then reduced slightly, and strained. Alternatively, the used court bouillon can be strained, chilled, and clarified with egg whites and aromatic vegetables. This is similar to a consommé. Finally, whole butter or cream may be added to a nage for richness. | textbooks/workforce/Food_Production_Service_and_Culinary_Arts/Flavors_of_the_Saucier%3A_Stocks_Sauces_and_Soups_(Zeringue_and_Thibodeaux)/01%3A_Chapters/1.01%3A_Light_Stocks.txt |
Brown Stock
Brown chicken stock is especially useful in kitchens where it is not practical to prepare meat glaces and beef stocks regularly. If the kitchen does not generate enough chicken carcasses for the stock, most wholesale butchers will deliver chicken carcasses at a nominal cost. Stewing hens can also be added to the stock for a fuller flavor, but this of course increases the stock's cost.
Brown chicken stock can be used for deglazing sauté pans and roasting pans and as a base for more concentrated, specialized stocks, such as game or pigeon. It is good to have brown chicken stock on hand to use as a thinner for sauces that may have become too reduced.
Brown Veal Stock. Roast all the ingredients for white veal stock, except the bouquet garni and water, in a 400°F (200°C) oven. Turn the meat, bones, and vegetables from time to time until they are evenly browned. Avoid burning any of the ingredients or letting the juices burn on the bottom of the roasting pan. Transfer the ingredients to a stockpot and add the bouquet garni. Deglaze the roasting pan with water. When all the juices have dissolved, add the deglazing liquid to the ingredients in the stockpot. Moisten, cook, and strain the stock as for white veal stock.
Mise en Place for a Brown Stock
• Cut up and wash bones.
• Peel and chop onions, carrots and celery for mirepoix.
• Prepare herb sachet.
A brown stock is made from chicken, veal, beef or game bones. The finished stock should have a good flavor, rich dark brown color, good body and high gelatin content. The primary differences between a brown stock and a white stock are that for a brown stock, the bones and mirepoix are caramelized before being simmered and a tomato product is added. These extra steps provide the finished stock with a rich dark color and a more intense flavor.
Caramelizing
Caramelization is the process of browning the sugars found on the surface of most foods. This gives the stock its characteristic flavor and color.
Procedure for Caramelizing Bones
For caramelizing, do not wash or blanch the bones as this retards browning. To caramelize:
1. Place the cut-up bones in a roasting pan one layer deep. It is better to roast several pans of bones than to overfill one pan.
2. Roast the bones for approximately 1 hour in a hot oven (375°F/190°C). Stirring occasionally, brown the bones thoroughly, but do not allow them to burn.
3. Transfer the roasted bones from the pan to the stockpot.
Deglazing the Pan
After the bones are caramelized, the excess fat should be removed and reserved for future use. The caramelized and coagulated proteins remaining in the roasting pan are very flavorful. To utilize them, deglaze the pan.
Procedure for Deglazing the Pan
• Place the pan on the stove over medium heat, and add enough water to cover the bottom of the pan approximately '12 inch (1.2 centimeters) deep.
• Stir and scrape the pan bottom to dissolve and remove all the caramelized materials while the water heats.
• Pour the deglazing liquid (also known as the deglazing liquor) over the bones in the stockpot.
Procedure for Caramelizing Mirepoix
1. Add a little of the reserved fat from the roasted bones to the roasting pan after it has been deglazed. (Alternatively, use a pan large enough to contain all the mirepoix comfortably.)
2. Sauté the mirepoix, browning all the vegetables well and evenly without burning them.
3. Add the caramelized mirepoix to the stockpot.
4. Almost any tomato product can be used in a brown stock: fresh tomatoes, canned whole tomatoes, crushed tomatoes, tomato puree or paste. If using a concentrated tomato product such as paste or puree, use approximately half the amount by weight of fresh or canned tomatoes. The tomato product should be added to the stockpot when the mirepoix is added.
Brown Stock Recipe
• Bones, veal, chicken or beef 16 lb (7 kg)
• Cold water 3 gal (11 lt)
• Mirepoix 2 lb (1 kg)
Sachet
• Bay leaves 2 (2)
• Dried thyme ½ tsp (2 ml)
• Peppercorns, crushed ½ tsp (2 ml)
• Garlic cloves, crushed 3 (3)
• Parsley stems 8 (8)
1. Place the bones in a roasting pan, in one layer and brown in a 375°F (190°) oven. Turn the bones occasionally to brown them evenly.
2. Remove the bones and place them in a stockpot. Pour off the fat from the roasting pan and reserve it.
3. Deglaze the roasting pan with part of the cold water.
4. Add the deglazing liquor and the rest of the cold water to the bones, covering them completely. Bring to a boil and reduce to a simmer.
5. Add a portion of the reserved fat to the roasting pan and sauté the mirepoix until evenly browned. Then add it to the simmering stock.
6. Add the tomato paste and sachet to the stock and continue to simmer for 6 to 8 hours, skimming as necessary.
7. Strain, cool and refrigerate.
Glace
Classic demi-glace is a stock that has been reduced and bound with starch until it has the consistency of a very light syrup or glace. Classic demi-glace is the basis for classic brown sauces. Natural demi-glace, also called coulis, is thickened by reduction or continual remoistening with additional meat; no starch is used in its preparation.
Glaces are stocks that have been slowly cooked down (reduced) to a thick syrup. These are convenient to have on hand in professional kitchens because they keep well and can be added to sauces at the last minute to give a richer flavor, a deeper color, and a smoother texture, Some chefs rely almost entirely on meat glace (glace de viande) for preparing brown sauces.
A glaze is the dramatic reduction and concentration of a stock. One gallon (4 liters) of stock produces only 1 to 2 cups (2.5 to 5 deciliters) of glaze. Glace de viande is made from brown stock, reduced until it becomes dark and syrupy. Glace de volaille is made from chicken stock, and, glace de poisson from fish stock. Glazes are added to soups or sauces to increase and intensify flavors. They are also used as a source of intense flavoring for several of the small sauces to be discussed.
Meat Glace (Glace de Viande)
Meat glace takes from 8 to 12 hours to prepare from already made stock. If it is difficult to work in a single stretch, the glace can be reduced for a couple of hours, allowed to cool, and then continued the next day. It is best to begin reduction of the bone stock in a wide-mouthed pot to encourage evaporation and rapid reduction. As the stock reduces, it should be transferred into clean pots of decreasing size. Usually three pots are required to reduce 10 quarts of stock.
Meat glaces can be prepared from any kind of stock, but the technique works best for stocks that already contain a fair amount of gelatin. For this reason, meat glace is most often prepared with a stock made from beef knuckle -bones, which release a large amount of gelatin into the surrounding liquid. Stocks containing little gelatin require too much reduction to become glaces, and by the time the reduction is complete, much of their savor has been compromised.
Fish Glace (Glace de Poisson)
Fish glace is prepared in the same way as meat glace except that fish stock is used instead of meat stock. Fish glace has a strong, fishy taste, which it can impart to sauces if used in more than tiny amount s. It is better to substitute reduced mussel or clam cooking liquid or reduced court -bouillon. If concentrated fish stock is required, prepare a double fish stock by moistening fish or fish bones with a previously made fish stock.
Procedure for Reducing a Stock to a Glace
Simmer the stock over very low heat. Be careful not to let it burn, and skim it often.
1. As it reduces and the volume decreases, transfer the liquid in to progressively smaller saucepans. Strain the liquid each time it is transferred into a smaller saucepan.
2. Strain it a final time, cool and refrigerate. A properly made glaze will keep for several months under refrigeration.
Glace De Viande (Modern) Recipe
Yield: 20 quarts
• 120 lbs. or 3 cases veal neck bones - roasted in roasting pans
• 10 lbs. roasted poultry bones, weigh after roasting
• 8 pigs feet (16 pieces split)
• 48 oz. tomato paste
• 3 liters red wine
• 10 lbs. onions, onions trimmings and leek greens-rough chopped and washed
• 4lbs carrots, peeled and rough chopped
• 4lbs celery, washed and rough chopped
• 8 bulbs of garlic, split across the middle
• 2oz. fresh thyme
• 1-Tbsp. black peppercorns
• 1-bay leaves
• ½ bunch parsley (utilize the stems, possible 3 bunches to equal the weight of 1 ½ bunches)
1. Add red wine and tomato sauce to a non-reactive pot and reduce by 2/3.
2. Roast all bones on full sheet pans until golden brown in color. Be careful not to burn.
3. Remove bones into stock kettle and reserve the pans.
4. Add a bit of water to the sheet pans and place over the stove to loosen the fonds. Add fonds the stockpot.
5. Caramelize the vegetables in batches and be sure to get a good color of caramelization. Have water nearby if you need to deglaze the pan often to ensure caramelization.
6. Add all ingredients to the kettle and set at setting 5.5 or 180 degrees for 48 hours. Strain through a china cap with a filter. Reduce stock down by 2/3 or to your liking.
Stock - Problems and Solutions
Problem Reason Solution
Cloudy Impurities
Stock boiled during cooking
Start stock in cold water; Strain through layers of
cheesecloth
Lack of Flavor Not cooked long enough
Inadequate seasoning
Improper ratio of bones to water
Increase cooking time; Add more flavoring ingredients; Add more bones
Lack of Color Improperly caramelized bones and mirepoix not
cooked long enough
Caramelize bones and mirepoix until darker. Cook longer.
Lack of Body Wrong bones used
Insufficient reduction
Improper ratio of bones to water
Use bones with a higher content of connective tissue; Cook longer; Add more bones
Too salty Commercial base used
Salt added during cooking
Change base or make own stock; do not salt stock
Essences
Contemporary chefs use essences, sometimes tightly bound with butter or oil, as light-bodied sauces.
Mushroom Essence
Mushroom essence is made by reducing mushroom cooking liquid to one-fourth its original volume. Mushroom cooking liquid is prepared by cooking mushrooms for 15 minutes in a covered pot with an equal weight of water (for example, I pound of mushrooms to 2 cups water). Although most recipes calling for mushroom essence assume that ordinary cultivated mushrooms are used, it is far better when prepared from wild types such as morels, cepes, or chanterelles.
Truffle Essence
Older recipes for classic sauces often call for truffle essence. Truffle essence is prepared by infusing sliced truffles in a small proportion of brown stock in a covered saucepan. Today, truffles are so scarce that it is unlikely that a restaurant would make truffle essence to have on hand to use in sauces. It is more likely that sliced truffles would be infused in the sauce itself or that the sauce would be finished with truffle butter or commercially available truffle juice.
Vegetable Essences
Almost any vegetable can be chopped and cooked in a small amount of stock, water, or wine. The method is almost the same as preparing a court bouillon except that the flavor of one vegetable is accentuated, rather than a combination. These flavorful essences can then be served as accompaniments to delicately flavored foods such as fish or can be combined with other ingredients for more complex sauces.
Classic Demi Recipe
• 1 qt. of brown stock
• 1 qt. of brown sauce (aka Espagnole sauce)
Combine the stock and sauce in a saucepan over medium heat. Simmer until the mixture is reduced by half. Strain and cool in a water bath.
Espagnole Recipe
• 1/4 c. of Clarified butter or neutral oil
• 1/4 c. of AP flour
• 1/2lbs of mirepoix, medium dice
• 1.25 qts. Brown Stock
• 1/2 tbsp. Tomato paste
• Salt and pepper to taste
Sachet
• 1/2 bay leaf
• 1 sprig of fresh thyme (or ½ tsp of dried)
• ¼ tsp of black peppercorns, crushed parsley stems
1. Make brown roux with butter and flour and set aside to cool completely
2. Sauté the mirepoix until caramelized
3. Add tomato paste to mirepoix and sauté for 30 seconds
4. Add stock and bring to a boil
5. Carefully whisk in roux breaking up any lumps
6. Once thickened reduce heat to a simmer and add sachet
7. Allow to simmer for approximately 45 minutes, allowing the sauce to reduce.
8. Skim the surface as needed to remove any impurities.
9. Strain through a chinois, hold for service or cool completely
This is a picture of our class glace de viande production storage. Photo Credit: Amelie Zeringue | textbooks/workforce/Food_Production_Service_and_Culinary_Arts/Flavors_of_the_Saucier%3A_Stocks_Sauces_and_Soups_(Zeringue_and_Thibodeaux)/01%3A_Chapters/1.02%3A_Brown_Stocks_and_Demi-Glace.txt |
Subsets and Splits