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Electric power consumed by an a.c. induction motor is measured and sensed changes in power factor are used to modulate the combined magnetic flux produced in the motor field by two sets of RUN windings. A main RUN winding set, which normally couples fully with the a.c. power, is engineered to have sufficient ampere-turns to produce just enough magnetic flux to operate the motor with a light load and maintain a moderately high power factor. Motor driven load increases are determined by sensing a corresponding increase in the power factor of the main RUN winding set, whereupon power flow to a secondary RUN winding is proportionately increased. Considerable energy savings occurs when the motor drives a fluctuating load due to reduced magnetic field excitation under all but full load conditions, with the result that energy ordinarily wasted by eddy currents, copper losses, and poor power factor operation is considerably lessened. Other possible losses due to harmonic distortion of the a.c. power waveform brought about by the phase-delayed thyristor control of the second run winding power are mostly swamped out and masked by the parallel, always-on major power draw by the main run winding. A motor speed-sensitive switch or relay may divert current around the thyristor and fully excite the second run winding during motor start-up, thereby producing full available motor torque during start-up while negating any electrical stress on the control thyristor.
1. Power control method for use with an electric induction motor,
comprising the steps of:
providing a source of alternating current electric power;
providing the motor with plural RUN winding means;
coupling a first RUN winding means with the source;
variably coupling a second RUN winding means with the source;
sensing reactive power factor of the electric power drawn from the source by the RUN winding means;
increasing the variable coupling when an increase in the power factor is sensed; and,
decreasing the variable coupling when a decrease in the power factor is sensed.
2. Power control method of claim 1 comprising the further steps of:
sensing instant voltage phase of the a.c. power coupled with the RUN winding means;
sensing instant reactive current phase of the a.c. power current flow coupled with the RUN winding means; and,
determining the reactive power factor by measuring the instant difference between the sensed voltage phase and the sensed current phase.
3. Power control method of claim 1 comprising the further steps of:
predetermining a minimum value of FULL LOAD motor power factor;
coupling substantially full a.c. power between the source and the second RUN winding means whenever the sensed power factor is higher than the predetermined minimum value power factor.
4. Power control method of claim 1 comprising the further steps of:
predetermining a minimum value of FULL LOAD motor power factor;
coupling substantially full a.c. power between the source and the second RUN winding means whenever the sensed power factor is higher than the predetermined minimum value power factor;
predeterming a maximum value of MINIMUM LOAD motor power factor;
coupling substantially no a.c. power between the source and the second RUN winding means whenever the sensed power factor is lower than the predetermined maximum value power factor; and,
proportionally coupling a.c. power between the source and the second RUN winding means for power factor values between the maximum value of MINIMUM LOAD motor power factor (minimum coupling) and the minimum value of MAXIMUM LOAD motor power factor (maximum coupling).
5. Power control method of claim 4 comprising the further steps of:
selecting an ampere/turns factor for the first RUN winding means suitable to produce sufficient motor field flux density to sustain operation with a minimum load coupled with the motor; and,
selecting an ampere/turns factor for the second RUN winding means suitable to produce sufficient motor field flux density such that when coupled fully with the source of a.c. power and combined with the flux density produced by the first RUN winding means, the combined flux density is sufficient to sustain operation of the motor when fully loaded.
6. Power control method of claim 1 comprising the further step of:
producing integral cycle control of any increase or decrease in variable coupling between the source and the second RUN winding means in which both half-cycles of any acted-upon full power cycle have about the same portion of ON time.
7. Power control method of claim 1 comprising the further steps of:
inductively coupling an ancillary pickup winding means with the first RUN winding means;
sensing the phase angle difference between the lagging voltage phase induced in the pickup winding means relative with the instant a.c. voltage phase coupled effectively across the first RUN winding means; and,
determining at least a relative value of reactive power factor thereform for producing control of the variable coupling between the source and the second RUN winding means.
8. Power control apparatus for use with an electric induction motor, comprising:
source of alternating current electric power;
induction motor means including at least a first RUN winding means and a second RUN winding means effective for producing motor field excitation;
means for coupling an inconstant load means with said motor means;
means for coupling the first RUN winding means with the electric power source;
means for producing variable a.c. electric power coupling between the source and the second RUN winding means;
means for sensing power factor; and,
means coupled with said power factor sensing means and said variable a.c. electric power coupling means, effective to produce a controlled increase in the coupling of a.c. power between the source and the second RUN winding means whenever an increase in power factor is sensed; and to produce a controlled decrease in the coupling of a.c. power between the source and the second RUN winding means whenever a decrease in power factor is sensed.
9. Power control apparatus of claim 8 further including means for starting the motor comprising:
START winding means;
means for initially coupling the START winding means with the a.c. power source;
means for decoupling the START winding means for the a.c. power source whenever the motor has attained substantial running speed; and,
means for coupling essentially full a.c. electric power between the source and the second RUN winding means whenever the START winding means is coupled with the a.c. power source.
10. Power control apparatus of claim 8 further comprising:
means for predetermining a non-linear relationship between the controlled increase and controlled decrease in the coupling of a.c. power with the second RUN winding relative with sensed changes in power factor; and,
means for coupling said predetermining means operatively with said means which produces said controlled increase and decrease.
11. Power control apparatus of claim 8 wherein said variable power coupling means comprises a.c. power phase control thyristor means coupled effectively between the a.c. power source and the second RUN winding means.
12. Power control apparatus of claim 11 wherein said variable power coupling means comprises means for producing integral power cycle symmetry of phase controlled a.c. power flow therethrough in which both half-cycles of any acted-upon full power cycle have about the same portion of ON time.
13. Power control apparatus of claim 8 wherein said power factor sensing means comprises:
means for sensing voltage zero-crossover of the a.c. power VOLTAGE PHASE cycle which essentially appears across the motor RUN winding means;
means for sensing current zero-crossover of the a.c. power CURRENT PHASE cycle which essentially appears flowing through the RUN winding means;
means coupled with said sensing means for determining an effective cycle-by-cycle phase delay signal indicative of the instant time difference between the sensed VOLTAGE PHASE cycle and the sensed lagging CURRENT PHASE cycle zero-crossover values; and,
means for adapting the determined phase delay signal coupled therewith into a control signal coupblable with the variable a.c. power coupling means and effective to produce an increase of a.c. power coupling therethrough whenever the determined time difference decreases, whilst a.c. power coupling therethrough decreases whenever the determined time difference increases.
14. Power control apparatus of claim 13 further comprising:
means for predetermining a minimum phase difference signal; and,
means for coupling the minimum phase difference signal with the measured phase delay signal adapting means, whereby essentially full a.c. power is coupled through the variable a.c. power coupling means whenever the measured phase difference is of a duration effectively less than the value of the minimum phase difference signal.
15. Power control apparatus of claim 8 further comprising:
means for combining the electromagnetic fields produced by the first RUN winding means and the second RUN winding means to provide motor field excitation.
16. Power control apparatus of claim 13 further comprising:
means for sensing CURRENT flow through the motor RUN winding means that includes providing a secondary pickup winding means tightly coupled magnetically with the RUN winding means resulting in an induced a.c. potential across the pickup coil means having a lagging phase relative with the voltage phase coupled across the RUN winding means; and,
means coupled with the pickup winding means effective for sensing zero-crossover of the induced a.c. potential.
17. Induction motor power control means comprising:
alternating current power source;
induction motor means including:
means for producing a first electromagnetic field;
means for producing a second electromagnetic field;
means for combining said electromagnetic fields;
means providing a rotatable output member;
means coupling said combined fields with said member and effective to produce rotation of said member;
means for coupling an inconstant load means with the output member;
means for coupling said first electromagnetic field producing means with said power source;
means for variably coupling said second electromagnetic field producing means with said power source;
means for sensing phase lag of the a.c. power flow between the electromagnetic field producing means and the power source relative with instant voltage phase of the power source; and,
means for determining a controlled increase in the efficacy of the variable coupling when the sensed phase lag decreases, and for determining a controlled decrease in the efficacy of the variable coupling when the sensed phase lag increases.
18. Power control means of claim 17 further comprising:
means for coupling substantially full a.c. power between said source and said second electromagnetic field producing means preferably as electrical contact set means coupled in shunt with said variable coupling means whenever said rotating member is running at less than a predetermined speed; and,
means for interrupting said full power coupling means whenever said rotating member is running higher than said predetermined speed.
19. Power control means of claim 17 wherein:
said means for sensing phase lag of the a.c. power which flows substantially through the electromagnetic field producing means further comprises induction pickup means inductively coupled with said field producing means resulting in an induced a.c. potential across the pickup coil means having a lagging phase relative with the a.c. voltage coupled across the field producing means.
20. Power control means of claim 17 further comprising:
said first electromagnetic field producing means comprising winding means predetermined to produce sufficient magnetic flux density to operate the motor means under minimum load; and,
said second electromagnetic field producing means comprising winding means predetermined to produce sufficient magnetic flux density which, when combined with the magntic flux density produced by said first field producing means, is sufficient to operate the motor means under full load.
My invention relates to fractional and integral horsepower electric induction motors particularly of the kind manufactured in large volume for use on major appliances, refrigerators, and air conditioners which drive a load that routinely varies over a range between full load and less than full load. The principal object for my invention is to teach a controller which serves to produce considerable ENERGY SAVINGS through load-related reduction of power flow to the motor under all but the full load conditions.
A.c. induction motors find ubiquitous application in major appliances, refrigerators, air-conditioners, and other machines of all sorts. Induction motors are cheap and simple to manufacture, and have an enviable record for long-term reliability without attention. Induction motors are relatively efficient electrically, when fully loaded. When lightly loaded, they also are notorious for wasting considerable amounts of electricity by consuming far more electrical power than what they are called upon to deliver as operating torque from their output shaft. It is this later rather troublesome shortcoming of common induction motors which needs improvement, and it is believed that this invention now can offer considerable relief.
To give some scope to the impact which induction motors have on society, one may consider that "125 million household refrigerators and freezers in operation today require the electricity from 30 standard (large sized) 1,000-megawatt power plants." ("Scientific American", Vol. 258, No. 4, April 1988, Page 56, in an article `Energy-efficient Buildings` by Arthur Rosenfeld and David Hafemeister.) Virtually all such refrigerators use induction motors. Considerable waste occurs because refrigerators do operate with varying mechanical load demands, while the typical hermetically sealed compressor assembly contains an induction motor which is sized to handle the worst case, ableit `normal`, compression load demand imposed upon it without frequent stalling. The result is simple: much of the time the motor is operating at less than full load and wasting a considerable amount of energy. Merely improving the dynamic operating efficiency of such a motor a mere ten-percent or so may result in the power saving equivalent to that afforded by 3 of the large 1,000 megawatt power plants, which are said to cost several billion dollars to construct. Some perspective of what this means can be obtained by considering an article which appeared in "New England Business" magazine, May 2, 1988, on pages 39-40 wherein the New England Power Pool (an organization which represents the region's utilities) estimates that by 1995 about 4,000-megawatts of additional generating capacity (on top of the present 23,000-megawatts of current capacity) would be needed just to keep up with demand growth. You also need to keep in mind that the highly controversial New Hampshire `Seabrook Unit I` and Plymouth, Mass. `Pilgram` nuclear power generating facitlities produce a combined power of only 1,820-megawatts: far less than what might be conserved through better induction motor operating efficiencies!Hence, improved efficiency in motor operation for refrigerators, air-conditioners, and other machines could down-scale the demand growth and alleviate some of the pressures which now exist in getting additional capacity on-line. Needless to say, greater improvements in motor efficiency can afford even more spectacular economic savings in power plant needs and reductions in attendant `wasteful` consumption of non-renewable fuel resources. Such further improvement in induction motor operating efficiency is precisely what is brought about by my instant invention.
Modern induction motors are often designed to operate with very high magnetic field flux densities in the stator structure. The result is near-saturation of the core material, with high eddy current losses. In addition, the windings may be designed to operate with high current densities that results in considerable heating due to winding resistance losses. Such winding losses are further aggravated in many cheaply designed appliance motors through the use of aluminum wire in lieu of the better and generally more efficient copper wire windings. Motor design my be dictated by competitive market conditions, resulting in agressive cost cutting. Cheap designs commonly translate into producing motors having high operating levels and the result may be a motor which operates with reasonable efficiency under full load, while under light load it is a wasteful of considerable energy. High temperature rise in a lightly loaded (or unloaded) motor is a sure sign indicating poor electrical operating efficiency. Modern motors operate very hot under all conditions of loading, which translates into poor overall performance efficiency when a widely varying load is being driven by the motor.
In earlier U.S. Pat. Nos. 4,052,648 and 4,266,177 Frank Nola describes how the a.c. pwoer fed to an induction motor might be controlled and therefore bring about some improvement in electrical efficiency. While he does measure the power factor of the operating motor and therefrom determines various control values for regulating the total power input of the motor run winding set by conventional phase-angle controlled firing of a triac, he greatly reduces and in some cases may negate any purported improvement by virtue of the severe a.c. power waveform harmonic distortion which his system reflects into the electric utility system. Nola also describes apparatus which is fraught with possibilities for maladjustment and drift, and wherein the correct operating points are not pre-established by design but rather they must be somewhat tailored to each unit which might be manufactured, resulting in a relatively labor-intensive and costly product. Column 3, lines 40-47 and column 6, lines 50-66 of U.S. Pat. No. 4,266,177 particularly describes the kind of twiddling that is needed to set the device's operating points relative with any particular motor's observed performance.
In yet another U.S. Pat. No. 4,533,857, Ten-Ho Chang et al show a motor controller which in effect measures the apparent current drawn by an induction motor and therefrom develops a variously retarded phase-angle control signal which fires a triac and thus modulates the total power flow to the motor. Like Nola, Chang et al shows the turn-ON of the full motor running current at some delayed point during each a.c. half-cycle and of course such an approach is fraught with severe harmonic distortion of the a.c. power flow (as reflected into the a.c. power lines), accompanied by resulting inefficiencies that may exceed any gain which could otherwise be obtained from use of the controller. Chang also does not recognize nor allow for the common characteristic of cheap induction motors wherein the lightly loaded (or even unloaded) apparent motor current may be only a little less than what full load motor current is. Although the motor current is lagging by perhaps 60 degrees or more, the actual measurable current which develops across the current transformer (Tr-2 in Chang's teaching) will be quite nearly the same as what develops under full motor load, when the motor current might lag by 30-degrees or less. A typical appliance motor, such as the General Electric type 5KH46JR15S has been found to draw about 7.9 amperes under full load, and yet continue to draw nearly 7 amperes of apparent current under NO-LOAD. Power factor also varied from about 80-85% under FULL-LOAD, to about 20-30% under NO-LOAD. This of course means that little change in current occurs and the circuit of Chang would operate ineffectively because slight changes in a.c. line voltage bring about more substantial changes in motor current than what changes in motor load produce. Chang is silent regarding compensation of apparent motor current changes which merely relate to commonplace a.c. line voltage fluctuations.
Noise, in the form of hum and buzz, are byproducts of stressful motor operating conditions. Magnetostrictive effects tend to produce substantial noise in the motor's structure, paticularly when stressed with the strong and abrupt changes in flux brought about by phase-delayed thyristor power control. These abrupt changes in induction fields can also set up other parasitic vibrations which, aside from being audibly annoying, can lead to premature structural fatigue of the motor's components (such as a vibrating loop of wire which eventually breaks off). Refrigerators and, to a lesser extent, air conditioners are frequently annoying sources of audible noise, albeit not particularly high in the sense of loudness on the commonly cited decibel scale for noise sources. Load related modulation of power flow to such motors may therefore serve to substantially abate such undesirable noise and result in a more acceptable product.
A.c. induction motors provide a very economical and time proven source of mechanical power for driving major appliances, air conditioners, and other kinds of domestic and commercial machines. The time-proven dependability of induction motors is exceptional, and years of product engineering have, in most cases, resulted in a simple and cost effective configuration using few parts. It is thus desirable to retain all these advantages of the induction motor, while coming forth with a meaningful reduction in energy waste which occurs when the motor is less than fully loaded.
Production of electric power in America is reaching a point where the utility companies in many parts of the nation will soon be nearing 100% capacity. Unless more generating capacity is soon built, brown-outs, power grid failures, and other cataclysmic power distribution events are likely to occur with increasing frequency because no reserve power capacity is available or being readied. In view of the many years it takes to get even a single new nuclear or conventional electric power generating facility on-line means that there is no quick and simple solution to this looming energy-crunch dilemma. The building of additional power plants is also a fundamentally costly proposition. Such cost can be illustrated by a 500-megawatt gas-fired power plant located in Burrillville, R.I. which cost about $320-million dollars and by a $300-million dollar plant planned for Woonsocket, R.I. which is oil-fired and produces a mere 180-megawatts. It therefore behooves manufacturers of any kind of apparatus that tends to waste a lot of electricity, relative to what it really "uses" to drive a load, to develop more ENERGY EFFICIENT schemes. Paramount in this arena of everyday power wasters are the ubiquitous induction motors, such as found on most major appliances and in air conditioners. Induction motors are subject for being `singled out` as power wasters due to the hunge number of such motors which find extended operation every day in out modern society. They often power machines and appliances which regularly operate daily for substantial periods of time. It is common that induction motors are desired by appliance and machine designers for any application where the motor will see a lot of use, due to their time-proven reliability and nearly zero-maintenance requirements. They also lend themselves to hermetic refrigeration compressor assemblies because there are no brushes to wear out or cause contamination of the refrigerant (and oil).
Ordinary engineering practice produces induction motor designs which operate with high magnetic field flux densities, high current density through the windings, and with a minimum of structure. The General Electric `Form V` industry standard no. 4096 motor, typically used with Whirlpool and Kenmore brand electric clothes dryers is representative of such minimal modern design practice. Producing about 1/3 horsepower, this motor draws about 5.6 amperes (full load), while under reduced load the apparent motor current remains about 5 amperes, albeit the power factor decreases substantially. Clearly it would be advantageous if the apparent motor current were to reduce in approximate relation with load decrease, while at the same time the power factor remains about constant. Without dynamic control of the motor operating conditions, such relatively constant power factor operation is unattainable in induction motors of ordinary (and economimcally cheap) design. My instant invention now teaches a controller which can expedite such a desirable characteristic from virtually any cheap motor design through the mere inclusion of two sets of RUN windings, one of which is constantly excited to provide sufficient magnetic field flux to drive the motor's rotor under reduced load conditions, while the other RUN winding is increasingly excited as the load increases. The combining of the separate magnetic fields produced by the two RUN winding sets serves to provide a variable operating flux density in the motor which is just sufficient to keep the motor running without stalling under any load condition between that of reducd load and full load, while at the same time economizing on the use of electrical energy. The inclusion of the second set of RUN windings in even cheap motors such as the aforementioned General Electric `Form V` or a `Form J` style imposes no significant manufacturing difficulty because the meter inclusion of a second set of RUN windings is little different from the manufacturing practice involved in winding separate START and RUN windings in the first place: e.g., the maker merely winds three sets of windings (with the two RUN windings being wound with somewhat lighter gauge wire) instead of the usual two winding sets.
My invention is illustrated with nine sheets of drawings showing twelve figures.
FIG. 1 - Functional diagram showing principal elements which comprise my invention.
FIG. 2 - Waveforms depicting signals which are essential for understanding the advantageous performance of my invention.
FIG. 3 - Operational diagram showing general circuitry configuration which enables practice of my invention.
FIG. 4 - Waveforms depicting signals which are found in the circuitry configuration shown in FIG. 3.
FIG. 5 - Modification of general circuit configuration of FIG. 3 to include a memory device which modifies the controller's dynamic characteristics.
FIG. 6 - Graphical plot of change in thyristor gate control signal delay relative with motor current phase lag.
FIG. 7 - Hookup of electrical elements of a typical refrigerator with my invention's control circuits.
FIG. 8 - Circuit for providing limited thyristor control range for the secondary RUN winding.
FIG. 9 - Circuit which adapts the circuit of FIG. 8 to give a different thyristor phase delay control range.
FIG. 10 - Waveforms depicting signals which are found in the circuitry configurations of FIG. 8 and FIG. 9.
FIG. 11 - Circuit which adapts the circuit of FIG. 8 to skew the thyristor phase delay control range even into the next half cycle.
FIG. 12 - Inductive pickup produces a sample of the RUN windinging lagging current phase.
My invention involves the use of an induction motor of ordinary commercial design which has been engineered to include two (or more) RUN winding sets. Ordinarily, a main RUN winding set is coupled directly with the a.c. power source, while a secondary RUN winding set is variably coupled through a thyristor with the a.c. power source. The main RUN winding set is predetermined to have sufficient ampere/turn capacity to produce the flux density to excite the motor field and achieve normal operation for light motor loads. The secondary RUN winding set is further predetermined to have sufficient additional ampere/turn capacity to produce additional magnetic field flux density which adds with the main RUN winding set flux density so as to obtain reliable operation of the motor in the range between that of a light load, which is excited by the main RUN winding set alone, up to a condition of full motor load. The main RUN winding set ordinarily is of more substantial construction, thereby providing a greater portion of the motor's total magnetic field excitation. A.c. phase control, or variable-phase power control as referred to in my invention is used in the general context which is more particularly explained in technical literature, such as in the General Electric Co. (Syracuse, N.Y.) "SCR Manual", 4-th Edition, Edited by F.W. Gutzwiller (especially sections 9 and 10).
In FIG. 1 the a.c. induction motor 10 is provided with a rotor 10-1 (that functionally drives a mechanical load which is not shown), a START winding 10-2, a main RUN winding 10-3, and a secondary RUN winding 10-4. In addition, the motor may include a `start` capacitor 10-21 and a centrifugal `start` switch 10-22. The main RUN winding couples directly with the a.c. power line L1, and through the current phase sensor 40 with power line L2. Thus, the main RUN winding is fully excited by the a.c. line power.
A voltage phase sensor 30 couples via lines 32-1, 32-2 with the a.c. power lines L1, L2 and produces a `voltage phase` signal on line 34 that couples with the input PE of the phase detector 50. Current flowing through the main RUN winding 10-3 also couples through the current phase sensor 40 (via lines 42-1, 42-2) which produces a lagging `current phase` signal on line 44 that couples with the input PI of the phase detector 50.
The phase detector 50 determines the phase difference between the `voltage phase` (reference) signal and the lagging `current phase` (error) signal, producing a phase difference signal on line 52 that couples with a proportional controller 60. The proportional controller functions to determine a range of proportional power control signals on line 62 in response to changes in the phase difference signal provided on line 52. The proportional controller usually determines the outputted signal on line 62 to have a larger dynamic range of electrical degrees of change than what is presented on the input signal line 52. It is common that an induction motor may have a range of lagging current which extends between about -20 degrees and -60 degrees (for example). Meanwhile, it is usually desirable that the thyristor 20 be enabled to phase control the power coupled with the secondary RUN winding 10-4 over a much wider range: say from about -0 to -180 degrees. In fact, in may practical motor applications it may be desirable to obtain the full 180 degree control of the thyristor gate delay with a mere 10 to 20 degree variation in motor current phase leg. How this expanded phase control variation is produced is one of the important aspects of my invention which shall be further explained.
A d.c. power supply 70 provides a source of low d.c. voltage 72-1, 72-2 for operation of the attendant electronic circuits which comprise the operational circuits that make up my invention.
In FIG. 2 I depict some waveforms which may give better understanding of my invention's central improvement. The waveform AE is typical of the kind of a.c. power control afforded by the earlier teachings of the mentioned Nola and Chang et al patents. You will see that the abrupt phase controlled turn-ON portion AEAA of the waveform AEBA gives rise to sudden changes in a.c. line conditions, and that these changes occur for every power half-cycle such as shown AEAB for the other half-cycle AEBB. When the phase-delay is even greater (in excess of -90 degrees), the half-cycle waveforms AEDA, AEDB are shown to have even shorter and more severe turn-ON AECA, AECB pulse transistions which cause the sudden power changes reflected into the a.c. power line to look almost like `spikes`. The result of such operation is power loss caused by the severe harmonic distortion of the power line waveforms, resistance losses due to the high current surge once turn-ON occurs, electrical noise, `flickering` of lights connected with the same power line, and other undesirable effects.
With my invention, the main RUN winding (such as winding 10-3 of FIG. 1) is fully excited by the a.c. waveform RWA of FIG. 2. This results in a symmetrical power flow RWAA, RWAB having negligible distortion. The controlled secondary RUN winding (such as winding 10-4 of FIG. 1) is partially excited by a thyristor controlled power flow represented by waveform RWB. In this case, the half-cycle waves are abruptly turned-ON RWBA, RWBB by the thyristor, and when sufficiently delayed may even appear like short `spikes` RWBC, RWBD. When combined with the steady, full-cycle power draw RWA of the main winding, the controlled power flow RWB is merely a portion of the total power flow, as shown by waveform RWC. The composite waveform RWCA, RWCB represents that of the steady power draw RWA combined with the controlled power draw RWB. In a like way, the waveform portion RWCC, RWCD shows the combination of the steady power draw RWA with the abrupt spikes RWBC, RWBD of waveform RWB. You should take particular note of the minimal effect the phase controlled secondary RUN winding power draw has on the overall waveform character, as shown by the composite waveform RWC. The improvement is surprising and leads to a remarkable increase in operating efficiency of my invention over that of the prior art.
A circuit overview for my invention appears in FIG. 3 and includes an induction motor 10 and the attendant RUN windings 10-3, 10-4. The main RUN winding 10-3 couples through a resistor 10-31 to the a.c. power line: the result is a voltage drop across the resistor having a phase relationship which mirrors the lagging current flow through the main RUN winding. The secondary RUN winding 10-4 couples with a triac 120, which includes a gate 122 that may turn the triac ON to obtain power flow from the a.c. power lines L1, L2. The capacitor 126-1 and resistor 126-2 operate as a snubber network to protect the triac against problems which may arise due to fast-rising voltage changes which may occur when the driven load appears inductive (e.g., fast dv/dt changes which can produce erratic commutation). The additional set of switch contacts 10-41 operate in concert with the `start` switch contacts 10-22 and therefore are closed during motor starting. The contacts serve to bypass the heavy start-up current rush around the triac 120. This novel arrangement protects the triac from unecessary abuse and enables the use of a motor economical, smaller rated triac because it has to merely handle the secondary RUN winding current when the motor is properly running, and not the excess current drawn during motor starting.
Inputs `A` and `B` of a voltage zero-cross detector 130 couple essentially with the a.c. line voltage (waveform E of FIG. 4) which appears across the line terminals L1, L2. A brief pulse signal (waveform XE of FIG. 4) is produced on line 134 each time the voltage waveform EA, EB goes through zero EXA, EXB (e.g., two pulses per cycle). The voltage pulse on line 134 couples with the SET input of a flip-flop latch 150, which when `set` produces a HIGH logic level on the Q output
Inputs `A` and `B` of a current zero-cross detector 140 couple with the a.c. voltage signal (waveform I of FIG. 4) which develops as a voltage drop across resistor 10-31 due to (lagging) current flow in the run winding 10-3. As a result, two pulses (waveform XI of FIG. 4) are produced on line 144 for each a.c. current cycle. As depicted in the waveform XI, the pulses XIAA, XIAB coincide in time with the less-lagging current waveform IAA, IAB zero-cross coincidence IAXA, IAXB. When the current lags more (as brought on by reduced power factor, or lighter motor loading) as shown by waveform IBA, IBB the zero cross pulses XIBA, XIBB shift in relative time to coincide with the zero-crossover coincidence IBAX, IBXB of the current waveform. In practice of my invention, the timing of the current zero-cross pulses XIBA, XIBB constantly shift about in time relative with the voltage zero-cross pulses XEA, XEB. The pulses produced on lien 144 then couple with the RESET input of the flip-flop 150, and when reset has ocurred a LOW logic level appears on the Q output. As shown by waveform LQ of FIG. 4, the latch 150 /Q output 152 signal (waveform LAA of FIG. 4) is set LOW by the voltage zero-cross, is held low for a period of time, and then returns HIGH (depicted by waveform LBA1, LBB1 or LBA2, LBB2 of FIG. 4) when the current zero-cross pulse XIAA, XIAB (or XIBA, XIBB) occurs.
The /Q output 152 from latch 150 couples with the RESET input of a delay counter 160. The delay counter is clocked from pulses on line 182-1 and is predetermined to count-up to a preestablished value on bus 160-1 which produces a LOW output from the decoder 162 on line 164 that couples with the RESET input of counter 166. It is my intent that counter 160 `delays` the onset of counter 166 operation for a brief period of time which coincides with the least value of lag delay (e.g., highest power factor) which may be reasonably expected from the induction motor load. When RESET of counter 166 goes `low` the counter will be clocked and advance by 0 to 15 counts (for example) depending upon the time which lapses between the decoder producing a LOW signal on line 164, and the occurrance of the next zero-cross current pulse. If current lag is relatively large (as with a light motor load) counter 166 advances further than what has time to do if the motor is more heavily loaded and the current lag is less. Waveform CP of FIG. 4 shows the relationship between the clock pulses CPN and the variations in timing of the current signal produced reset of latch 150 as depicted by waveforms LBA1 and LBA2.
The advanced states on the counter 166 output bus 166-1 couple with the DATA input of an edge triggered latch 170. The input data is thus transferred to the output bus 170-1 the instant the /Q output of latch 150 goes HIGH. Latch 170 thusly serves to store the most recent count value while the counter 166 is recounting during the next time period. In order to produce symmetrical a.c. power control (which acts to reduce harmonic distortion and line imbalance losses) I provide that each controlled a.c. power cycle is self-completing: i.e., the first and second half-cycles are of about the same duration. A divide-by-two flip-flop 158 is clocked from the latch 150 Q output LOW-to-HIGH transistions, producing a pulse on line 158-1 the transistion of which is in-phase with the a.c. power voltage phase. The resulting pulse serves the CLOCK the edge-triggered data latch 172 that effectively transfers the byte signal on bus 170-1 to bus 172-1 once during every a.c. power voltage phase cycle.
A clock 180 produces a relatively high-frequency signal which is divided-down by the counter 182, producing a signal of necessary frequency to clock counters 160 and 166. In addition, a lower-frequency signal (say 1,920 hertz for 60 hertz a.c. power) couples with the CLOCK input of a 4-bit counter 184. The RESET input of the counter couples with the voltage zero-cross pulse signal on line 134, and is therefore reset at the onset of each a.c. power half-cycle. After reset, the counter quickly advances from count `0` to count `15` (binary 0000 to binary 1111) on bus 186. A comparator 174 receives an A-IN signal from the latch 172 output data bus 172-1 and a B-IN signal from the counter 184 output bus 186. When the counter 184 `counts-UP` to a binary weight signal that equates to the stored binary signal appearing on bus 172-1, coincidence of A=B in the comparator produces a HIGH pulse signal on output 174-1 that couples through the triac driver 124 to produce a signal on line 122 that operates the gate of the thyristor 120 to effectively turn the thyristor ON during the rest of the instant a.c. power half-cycle. Waveform TG in FIG. 4 depicts the thyristor gate turn-ON signal pulse timing relative with the plural clock pulses CPN. To interpret this waveform, it shall be seen that the pulse TGPA occurs at the onset of the a.c. power 180-degree half-cycle when the signal on bus 172-1 is binary 0000 because coincidence occurs in the comparator immediately at the start of the half-cycle. Conversely, if the signal on bus 172-1 has a binary weight of 1111 then counter 184 must count-UP 16 steps and thus coincidence in the comparator is delayed in time until near the end of the half-cycle, as depicted by pulse TGPB. Of course different byte signal weights on data bus 172-1 will produce pulses having timing intermediate of TGPA and TGPD (i.e., laying between about 0- and 180-degrees of electrical phase delay prior to thyristor 120 turn-ON.
A computer program can serve to develop the best clock frequency choices, as determined by specifying a range of minimum and maximum current phase delay (e.g., power factor range). Furthermore, the values can be optimized to restrict the dynamic range of thyristor control. For example, the values can be determined such that the thyristor always operates over a range of phase delays considerably less than the full 0- to 180-degree maximum capability. The following program may be utilized for such operative selections:
__________________________________________________________________________10 'DETERMINATION FOR CLOCK FREQUENCY OF PHASE-LAG COUNTER @:CFPLC.BAS V1.020 '(c) H. Weber -=- K1VTW -=- 4/11/88 -=- CP/M-80 -=- MBASIC-80 -=- DEC VT-18030 GOSUB 650:GOSUB 66035 PRINT:GOSUB 64540 PRINT "THIS PROGRAM WILL QUICKLY DETERMINE THE CLOCK FREQUENCY FOR THE"50 PRINT "PHASE-LAG ACCUMULATOR COUNTERS RELATIVE WITH DIFFERENT POWER FACTORS."55 GOSUB 64560 GOSUB 67070 INPUT "LOAD Motor Model No. or Description: ",MN$80 IF LEN(MN$)>30 THEN 3090 PRINT:INPUT "Enter MAXIMUM LOAD Current Lag in Degrees ",PFA100 IF PFA>90 OR PFA<0 THEN 90110 PRINT:INPUT "Enter MINIMUM LOAD Current Lag in Degrees ",PFB120 IF PFB>90 OR PFB<0 THEN 110130 IF PFA>PFB THEN 90140 PRINT:INPUT "Accumulator Counter Division Factor `n` ",NF150 IF NF<2 OR NF>256 OR NF>INT(NF) THEN 140160 PRINT:INPUT "Enter Power Line Frequency (Hertz) ",LF170 IF LF<25 OR LF>400 THEN 160180 PRINT:INPUT "Enter MINIMUM Thyristor Gate Delay (Degrees) ", PDL190 IF PDL<0 OR PDL>180 THEN 180200 PDR=180-PDL=PDR/(NF-1)210 PFR=PFB-PFA:PFS=PFR/(NF-1)220 FCK=(2*LF*NF)*(180/(PFB-PFA)*(180/(180-PDL))230 PCK=LF*2*NF240 CDV=FCK/PCK:CDN=INT(CDV)250 IF CDV>CDN+.5 THEN CDV=CDN+1 ELSE CDV=CDN260 GOSUB 650:GOSUB 660270 PRINT "LISTING OF THYRISTOR TRIGGER DELAY RELATIVE WITH MOTOR CURRENT LAG."280 GOSUB 620290 PRINT "|";:PRINT TAB(6) "Motor Current";:PRINT TAB(20) "|";300 PRINT TAB(25) "Thyristor";:PRINT TAB(40) "|";310 PRINT TAB(41) STRING$(38,"˜");:PRINT TAB(80) "|"320 PRINT "|";:PRINT TAB(6) "Lag, Degrees";:PRINT TAB(20) "|";330 PRINT TAB(23) "Conduction Angle";:PRINT TAB(40) "|";340 PRINT TAB(43) "Clock Frequency:";:PRINT TAB(61) FCK;350 PRINT TAB(73) "Hertz";:PRINT TAB(80)"|"360 GOSUB 640370 FOR AA=1 TO 16380 PRINT "|";:PRINT TAB(7) "-"; (PFA)+((PFS*AA-PFS);390 PRINT TAB(26) (PDL+(PDS*(AA)-PDS);400 PRINT TAB(40) "|";410 IF AA=1 THEN PRINT TAB(43) "MIN. Current Lag:";:PRINT TAB(63) "-";PFB;420 IF AA=1 THEN PRINT TAB(71) "Degrees" ;430 IF AA=3 THEN PRINT TAB(43) "MAX. Current Lag:";:PRINT TAB(63) "-";PFA;440 IF AA=3 THEN PRINT TAB(71) "Degrees";450 IF AA=5 THEN PRINT TAB(43) "Counter Factor `N`:";:PRINT TAB(64) NF;460 IF AA =5 THEN PRINT TAB(72) "Stages";470 IF AA=7 THEN PRINT TAB(43) "Gate Delay Counter";480 IF AA=8 THEN PRINT TAB(43) "Clock Frequency:";:PRINT TAB(62)PCK;490 IF AA=8 THEN PRINT TAB(73) "Hertz";500 IF AA=10 THEN PRINT TAB(42) FCK "Hz/" PCK "Hz,";510 IF AA=11 THEN PRINT TAB(45) "Rounded Off =";:PRINT TAB(64) CDV;520 IF AA=11 THEN PRINT TAB(72) "Counts";530 IF AA=12 THEN PRINT TAB(41) STRING$(39,"-");540 IF AA=13 AND MN$>""THEN PRINT TAB(43) "Listing Based on Motor Model:";550 IF AA=14 THEN PRINT TAB(43) MN$;560 IF AA=50 THEN PRINT TAB(41) STRING$(39,"˜");570 IF AA=16 THEN PRINT TAB(43) "(c) Harold J. Weber ++ April 1988";580 PRINT TAB(80) "|"590 NEXT AA600 GOSUB 620610 END620 PRINT "|";:PRINT STRING$(38,"-");:PRINT "|";630 PRINT STRING $(39,"-");:PRINT "|";:RETURN640 PRINT "|";:PRINT STRING$(38,"-");:PRINT "|";:PRINT TAB(80) "|":RETURN645 PRINT STRING$(70,"-"):RETURN650 PRINT CHR$(27)"[2J";:RETURN 'Clear Screen (CLS) | ANSI Settings660 PRINT CHR$(27)"[H";:RETURN 'Home Cursor (HOM) | for DEC VT-180670 PRINT CHR$(27)"8;1H";:RETURN 'Position Cursor | Computer__________________________________________________________________________
D.c. power is provided on lines 72-1, 72-2 as produced by a d.c. power supply 70 that couples with the a.c. line L1, L2.
The control of power flow between the a.c. source and the second RUN winding follows a relatively straight-line character when practiced with the hookup of FIG. 4. Curve 6A of FIG. 6 depicts the general relationship between thyristor trigger gate delay and sensed changes in motor current lag.
The relationship between the gate delay and motor current phase lag may be advantageously modified into substantially any reasonable non-linear relationship through the inclusion of a characterization memory 173 as shown in FIG. 5, which is coupled between the output bus 172-1 of latch 172 (of earlier FIG. 4) and the A-IN input of comparator 174 as provided on the memory output bus 173-1. Through artful predetermination of the characterization memory's stored states, the data brought forth on the memory's output D-OUT as delivered on the output bus 173-1 may be compensated relative with the data present on the data bus 172-1 coupled with the memory's input AD-IN (which serves to address the memory cells) so as to produce control of the motor's second RUN winding current in such a way that best overall smoothness of control is obtained. Memory 173 may be a relatively small ROM (Read-Only Memory) or PROM (Programmable ROM): for example, if data provided by the latch 172 is 8-bits wide the memory merely needs to be 256-bytes (e.g., 2048 bits). Curve 6B of FIG. 6 depicts a modified transfer characteristic for the controller which may be obtained through the characterization memory's predetermined data contribution to the earlier FIG. 4 hookup. However, virtually any transfer characteristic can be obtained through preset programming of the memory.
A wiring hookup which typifies a common refrigerator or small air conditioner is shown in FIG. 7 to include a hermetic motor-compressor unit 200 which has a rotor 202 that drives the compressor. A START winding 204 is provided, together with a first RUN winding 206 and a second RUN winding 208. The voltage which appears between the line terminals L1, L2 also couples with the voltage zero-cross detector 210, producing a pulse on line 212 concurrent with each half-cycle voltage phase reversal. Current flow through the first RUN winding 206 also flows through a sense resistor 222, where the voltage drop developed thereacross by the lagging RUN winding current flow is coupled with a current zero-cross detector 220, producing a pulse on line 224 concurrent with each current half-cycle phase reversal.
I provide a means 230 for determining a.c. power flow to the run winding R2 which receives the zero-cross pulses on lines 212, 224 (inputs EX and IX respectively), and therefrom determines the timing for the pulses on line 232 that drives the gate of the triac 240. Operation is such that any increase in RUN winding current flow lag (which generally indicates reduced motor loading) results in an increase in delay of the triac gate trigger pulse; e.g., the triac turns-ON later in the half-cycle.
As is usual practice with refrigeration motors, a potential relay 250 is utilized for starting the motor. The contact set 254 is initially closed, and current flows to the START winding 204 and the starting capacitor 260. When the motor speed builds-up, the voltage increases across the START winding exciting the relay field 252, which pulls the armature in separating the contact set 254 and ending START winding current flow. Another set of contacts 256 which are initially closed mechanically operate in conjunction with the start contact set. The contact set 256 connects in parallel with the triac 240, serving to shunt the heavy current flow which occurs during motor starting away from the triac. D.C. power for circuit operation is provided by a power supply 70', producing the d.c. power on lines 72-1', 72-2'.
The second RUN winding may be modulated with considerably less than full half-cycle variation and produce good power reduction to the motor. This unique ability comes about because most of the operating flux for the motor field is produced by the first RUN winding, while the second RUN winding merely has to supplement the field strength in approximate proportion to changes in motor loading, as detected through power factor changes. FIG. 8 shows a split-phase motor 10' having a rotor 10-1', START winding 10-2', and two RUN windings 10-3', 10-4'. A current sensing resistor 10-31' couples between the a.c. power line L1 and the first RUN winding 10-3'. The voltage developed across the resistor couples with the current zero-cross detector 140', producing a pulse on line 144' each time the current cycle reverses phase (e.g., two pulses per cycle). This pulse is coupled through a traic driver 124', providing a signal on line 122' that directly drives the gate of the triac 120'. In effect, the lagging current phase is compared with the zero-cross timing of the voltage phase of the a.c. power signal which serves to commutate the triac 120'. This of course is obviously equivalent to determining phase relationships through the use of a separate voltage zero-cross detector, such as element 130 of FIG. 3. In this arrangement of my invention, the motor load dependent variation in RUN winding current lag is all the variation which is submitted to the triac gate for modulation of the second RUN winding 10-4'. In practice, the motor current may vary from about 30 degrees to about 60 degrees, and thus the power coupled through the triac will vary by the same amount and over substantially the same range: e.g., about 30 degrees of maximum variation. When the first RUN winding is sized to be very much dominant, the second RUN winding may serve to add 0- to about 15-percent of the overall motor operating flux, and the modulation of the winding with this reduced angular variation of the power cycle provides sufficient control.
The curves E, I, and XI of FIG. 10 are similar to those of FIG. 4, whereas the curve RP1 shows how the FIG. 8 controller produces a variation in the turn-ON range of the power cycle. A fully loaded motor has smallish current phase lag, say about 30-degrees, and the triac will turn-ON RPAA, RPAB early in the power cycle RP1. When more lightly loaded, the RUN current lags more and this translates into the triac being turned-ON RPBA, RPBB later in the power cycle RP1. The variation in current lag (or power factor) produced by load variations serves to vary the triac turn-ON over the dynamic range RV1 to RV2.
Through the inclusion of a phase delay counter 148, which is driven by a clock 181 in FIG. 9, I produce a retarded pulse signal transistion on line 148-1 that couples with the triac driver 124' to serve to turn the triac ON at a different phase angle timing other than the instant of current phase lag zero-crossover, as was done in the teaching of FIG. 8. Representative circuit timing is depicted in FIG. 10, where the waveform QA represents the output from the counter 148-1 which is obtained when the current phase-lag is small. The counter is effectively RESET by the output from the zero-cross detector 140', driving the QA output signal QAA to logic LOW. The reset counter then counts for a finite period of time, which when completed produces a LOW-to-HIGH transistion QAB that serves to turn the triac ON (in this case at the onset GA of the next half-cycle, shown in waveform RP2). A more retarded lagging current signal resets the signal QB at the time QAA', and like before counting occurs and timely produces the LOW-to-HIGH transistion QAB' that turns the triac ON (later GB in the next half-cycle). Dynamic variation then extends between GDVA to GBVB. Through different counter 148 choices, or clock rates, the thyristor turn-ON can be arranged for any reasonable point in the cycle subsequent to the occurance of the current zero-cross pulse. Setting the count so that the 30-degree (or so) range of control occurs during the middle 30-degrees of each a.c. power half-cycle makes for the largest change in second RUN winding power.
The inclusion of a decoder 149 that couples with the counter 148' is shown in FIG. 11, and is desirable to allow more precise phase delay control. The output 148-2 form the counter (which ordinarily includes one line for each counter stage) couples with the input of a DECODE-BY-`n` decoder 149 which can be predetermined to respond to any number of counts from one up to any reasonable number. As an expedient for the artisan who may attempt to duplicate the fruits of my invention, the following BASIC computer program can quickly serve to determine;
a. the value `n` for the decoder 149;
b. the number of stages for counter 148';
c. the relationship of the CLOCK 181 Frequency relative with the counter stages and decoder value;
d. the relationship of various power factor related phase delays with circuit predeterminations; and,
e. the relationship of triac gate signal phase skew with other circuit predeterminations.
By entering the value of clock frequency, phase lag values, and desired skew the best operating values for the circuit of FIG. 11 can be found. The best circuit conditions may also be found which provide for mid-cycle control range of the next a.c. power half-cycle, thus providing for optimal dynamic range.
__________________________________________________________________________10 'PROGRAM FOR DELAYED CYCLE PHASE CONTROL @:DCPC1.BAS20 'Copyright 5/6/88 H. Weber K1VTW MBASIC-80 CP/M-80 DEC VT-180 V1.030 '- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -40 PRINT:GOSUB 1000:GOSUB 101050 PRINT:GOSUB 1020;:PRINT "QUICK-DETERMINATION OF FIG. 11"60 GOSUB 1020;:PRINT " DECODER and COUNTER PARAMETERS"70 PRINT:PRINT:PRINT "What is the POWER LINE FREQUENCY ?? (In HERTZ)";80 PRINT TAB(60);:INPUT LF90 IF LF<50 OR LF>400 THEN 40100 PRINT:PRINT "Do You Want to delay Thyristor Turn-ON"110 PRINT "Into NEXT Half-Cycle ? )Y( or )N(";120 PRINT TAB(60);:INPUT AFL$130 IF AFL$="N" OR AFL$="n" THEN FLA=1:GOTO 160140 IF AFL$="Y" OR AFL$=" y" THEN FLA=0:GOTO 160150 GOTO 100160 PRINT:PRINT "Enter CLOCK Frequency in HERTZ:";170 PRINT TAB(60);:INPUT CKA180 IF CKA<1000 OR CKA>1E+06 THEN 160190 IF FLA=1 THEN 230200 PRINT:PRINT "What is MINIMUM (Full Load) PHASE LAG in Degrees ??";210 PRINT TAB(60);:INPUT MNL220 IF MNL<0 OR MNL>89 THEN 200230 PRINT:PRINT "What is MAXIMUM (Min. Load) PHASE LAG in Degrees ??";240 PRINT TAB(60);:INPUT MXL250 IF MXL<MNL OR MXL>90 THAN 230260 IF FLA=1 THEN 390270 PRINT:PRINT "During the NEXT HALF-CYCLE you may specify:"280 PRINT:PRINT " )1(. MINIMUM PHASE DELAY In Degrees; or,"290 PRINT " )2( To CENTER THE PHASE CONTROL Range MID-CYCLE:":PRINT300 PRINT TAB(20) "Enter Your Choice. . . )1( or )2(:";310 PRINT TAB(60);:INPUT FLD320 IF FLD=1 THEN 340330 IF FLD=2 THEN 380 ELSE 300340 PRINT:PRINT "What is the Desired NEXT CYCLE"350 PRINT TAB(15) "MINIMUM PHASE DELAY In Degrees !!";360 PRINT TAB(60);:INPUT DLC370 GOTO 470380 IF FLA=0 THEN 470390 PRINT:PRINT "During the SAME HALF-CYCLE,"400 PRINT " Enter Desired DEGREES of TIME-SKEW:";410 PRINT TAB(60);:INPUT SKW420 IF SKW<=0 THEN PRINT "Phase SKEW Must Be Greater than Zero":GOTO 400430 IF SKW+MSL>180 THEN PRINT "Desired Time Skew TOO BIG":GOTO 360440 SKA=180-MXL450 IF SKW<SKA THEN 470460 PRINT "Phase SKEW Must be LESS Than"SKE "Degrees":GOTO 400470 IF FLA =0 THEN SKW=(180-MNL)+DLC480 IF FLA=0 AND FLD=2 THEN SKW=(180-((MXL+MNL)/2))+90490 CKB=(1/(((1/LF)/360)*SKW))500 CKC=CKS:SKT=(1/CKB)*1000:CKD=CKA510 IF CKC<2*CKB THEN PRINT "CLOCK Frequency TOO LOW":PRINT:GOTO 160520 IF CKD=<CKB THEN 550530 NSX=NSX+10:CKD=CKC/NSX540 GOTO 520550 IF CKD=>CKB THEN 580560 CKD=CKC/NSX:NSX=NSX-1570 GOTO 550580 IF (CKB-CKC)>((CKC*2)-CKB) THEN NSX=NSX-1:CKC=CKC*2590 CSX=NSX600 IF CSX=<1 THEN 630610 CSX=CSX/2:CNT=CNT+1620 GOTO 600630 IF CKD>CKB THEN PCT=((CKD-CKB)/CKB)*100 ELSE PCT=((CKB-CKD)/CKB)*100640 PCT= (INT(PCT*100))/100650 SKD=(1/CKD)*1000:SKE=(PCT/100)*SKW660 GOSUB 1000:GOSUB 1010670 GOTO 680680 PRINT:GOSUB 1020;:PRINT "OPERATING VALUES FOR FIG. 11 CIRCUIT":PRINT690 PRINT "The following VALUES and PARAMETERS have been";700 PRINT " determined for the COUNTER and"710 PRINT "DECODER Circuit Elements of FIG. 11, as derived";720 PRINT " from the Motor Current Phase"730 PRINT "Lag parameters and the desired operating conditions";740 PRINT " for the circuit."750 PRINT:PRINT "Selected CLOCK FREQUENCY is:";:PRINT TAB(50) CKA " Hertz"760 PRINT770 IF FLA=0 THEN PRINT "Total Phase Skew (and into NEXT CYCLE) is:";780 IF FLA=1 THEN PRINT "SAME CYCLE Phase Skew is:";790 PRINT TAB(50) SKW " Degrees"800 PRINT:PRINT "Selected Phase Skew TIME DELAY is";810 PRINT TAB(50) SKT " milliseconds"820 PRINT:PRINT "ACTUAL Phase Skew TIME DELAY is:";830 PRINT TAB(50) SKD " milliseconds"840 PRINT:PRINT "The Resulting PHASE SKEW ERROR is:";850 PRINT TAB(50) SKE " degrees"860 PRINT:PRINT "DECODER 149 should be set to decode:";870 PRINT TAB(50) NSX " counts"880 PRINT:PRINT "The Decoded COUNT ERROR is:";890 PRINT TAB(50) PCT " percent"900 PRINT:PRINT "COUNTER 148 needs:";:PRINT TAB(50) CNT " stages"999 END1000 PRINT CHR$(27)"[2J";:RETURN 'CLEAR SCREEN (CLS) | ANSI values are1010 PRINT CHR$(27)"[H";:RETURN 'HOME CURSOR (HOME) | for DEC VT-1801020 PRINT CHR$(27)"#6";:RETURN 'DOUBLE WIDTH CHARACTERS | microcomputer.__________________________________________________________________________
The control circuits of FIG. 9 and FIG. 11 are quick in operation. That is to say, they respond rapidly to any change in motor loading. It is usual that the current lag will instantly change whenever the motor `dynamics`, e.g. loading, change in any way. This change is acted upon immediately, either later in the same half-cycle as taught in FIG. 9, or else in the next half-cycle as might be provided by the teaching of FIG. 11. In either case, control is obtained within the time period of the same cycle: or for 60-hertz power, the response is typically on the order of 5 to 12 milliseconds.
A tertiary winding 10-5 may be interwound with the main RUN winding 103 as shown in FIG. 12, and the inductive coupling will produce an a.c. signal which may couple with the zero-cross detector 140". The typical teritary winding may consist of a few winding turns which are wound together with the RUN windings 10-3'and 10-4'. The induced voltage will LAG the applied voltage, and the induced voltage LAG will be comparable with the motor current lag: hence, equatable with power factor. Combining the essence of the FIG. 12 circuit with the teachings of FIG. 11 provides for very economical control of common induction motors, such as the permanent split capacitor motor 10 which I show.
While I have endeavored to teach my invention in a particular form which can be convienently described, such choice is merely for purpose of illustration and shall not construe any limitation on my invention when it is practiced in any other alternative form which may bring form substantially the same performance results.
Discrete circuit devices have been chosen to perform the necessitous operational tasks and such choice enables a concise description for the invention's novel performance. A skilled artisan might also choose to use a microprocessor or any combination of other known elements to practice the invention. It is thus to be clearly realized that it is the underlying essence of my invention: that of providing reduced power consumption and lessened harmonic distortions of the a.c. power line, which dominate these teachings. Such improved performance is mostly obtained through the use of more than one RUN winding, wherein the a.c. power fed to one RUN winding is usually controlled in proportion to motor loading as determined mainly by changes in current phase lag (i.e., power factor) while the other RUN winding is fully excited by a.c. power. A skilled artisan may reasonably be expected to find other combinations of circuit elements which will serve to modulate the motor's operation in a like way, and such engineering variations merely serve as expedients enabling the ready practice of my invention, wherein my invention's novelty resides in the appended claims.
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subset: commoncrawl


text:
The Nintendo 64 had Super Mario 64; the Xbox had Halo: Combat Evolved; the Wii had Wii Sports.
From Game & Watch to N64 to Wii, relive your greatest Nintendo memories while watching this funky animation.
Even on the radically underpowered Wii, Nintendo was making games that stood out from the crowd.
trademarked name of a Japanese company that makes video game systems, consoles, and software
The founder of Nintendo stepped down in 2002.
Ninten 'leave luck to the heavens' + do 'company'


text:
VIEWS: 0 PAGES: 1 POSTED ON: 9/29/2012 Public Domain
Date: Thu, 15 Jun 2006 10:22:19 -0400 From: "REPROHEALTHLAW-L : Reproductive and Sexual Health Law Programme" Subject: [RHLAW] IACHR Report: Situation of HR Defenders in Americas Inter-American Commission on Human Rights, Report on the Situation of Human Rights Defenders in the Americas, 2006, OEA/Ser.L/V/II.124, Doc. 5 rev. 1 (7 March 2006) Human rights defenders undertake vital work seeking to ensure the effective observance of human rights and fundamental freedoms of individuals everywhere. This notwithstanding, the Inter-American Commission on Human Rights (IACHR) has recently expressed serious concern regarding "the grave situation of insecurity and danger in which human rights defenders must pursue their work". Extra-judicial executions, forced disappearances, assaults, threats, and harassment represent just some of the methods employed "to impede and encumber" the work of human rights defenders. The IACHR's Report on the Situation of Human Rights Defenders in the Americas identifies many of the risks and patterns of violations affecting human rights defenders in that region. Articulated in a legal framework, the report examines a number of issues, including: the importance of human rights defenders in a democratic society, problems experienced by human rights defenders, State responses to this issue, and the legal framework of protection available under the Inter-American system. The Report also recommends a number of measures to legitimate, promote, and protect the invaluable work of human rights defenders. Available online in the Spanish original, as well as translations to English, French and Portuguese: http://www.cidh.oas.org/countryrep/Defenders/defenderstoc.htm
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http://turntable.fm/indie_alt_rock8 with kylie and tello as usual
http://turntable.fm/indie_alt_rock8 with kylie and tello as usual
Upcoming Shows:
U2: 6/28 @ United Center
Lollapalooza: 8/1 @ Grant Park
This room was a lot of fun on Friday night
I made a room:
Fun time in KCRW. Thanks again.
Last edited by suprefan; 07-08-2011 at 01:29 PM.
Alt Nation
Last edited by Justin170; 07-09-2011 at 05:11 PM.
So much good music has been played in this room tonight
If you have Chrome, or maybe would switch because of this. Check it out.
edit: http://turntable.fm/breakfast_club
Last edited by suprefan; 07-10-2011 at 12:25 PM.
There's a contingency of Coachella vets in the room "WOXY_lives" right now, too cool.
ha ha i am one of those people, I have been in that room for hours now drinking
If only you had held up your end of the deal!
They need to develop an android app or make it work on IE so I can sit in there all day at work.
I'm thinking of doing a bit of an experiment on my college radio show this Thursday, by creating a Turntable room and just broadcasting that music live. I need some DJs who I can trust to play songs that will fit the station's format ("progressive" - basically anything you wouldn't hear on standard radio stations) and that also don't violate the FCC's rules regarding obscenities and indecencies. Anyone interested in joining sometime between 9 and 11 PM EST tomorrow night?
Can turntable.fm broadcast through a radio stream?
^ same here. Found out yesterday when I tried to get on. My work won't let anyone but an administrator download new browsers.
May 15-17 - Psycho California
June 6 - The Rolling Stones
June 10 - Melvins
June 20 - Blur
June 24-28 - Glastonbury
July 18 - Death Grips?
July 26 - Faith No More
September 25 - Kraftwerk
Same here. I said something on their facebook wall and got a response from another user about turntable only being in beta right now. Well no shit. I do get on it in the evenings for a bit though. I will likely be a regular user of it. I like it a lot.
I want to check this out, but need an invite from the site or someone who is already in right?
If one of your friends on Facebook has access to it you can get in.
May 15-17 - Psycho California
June 6 - The Rolling Stones
June 10 - Melvins
June 20 - Blur
June 24-28 - Glastonbury
July 18 - Death Grips?
July 26 - Faith No More
September 25 - Kraftwerk


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We were pleasantly surprised when they dropped the zombie riff "Shaun Of The Dead," we were more than pleased to see them keep up the quality and laughs in the buddy cop romp "Hot Fuzz," but could Edgar Wright, Simon Pegg and Nick Frost do it again? Could they say goodbye to the Cornetto trilogy and...Read More »
It seems rumors are flying fast and furious this week for nerd franchises, so let's get a handle on them, and kick off with one that is actually legit, followed by a couple others that are sort of ridiculous...Read More »
"After 'Hot Fuzz' we always thought it would be rude not to wrap the films up in a neat trilogy," director Edgar Wright recently told Yahoo! Movies about "The World's End," the upcoming last film in his mooted Cornetto trilogy (a British ice cream that features in all three movies). "I think it's a ...Read More »
We've got Supermen and Jaegers and Wolverines still to come this summer, but it's fairly likely that we'd trade them all for a chance to see Edgar Wright's "The World's End" a touch earlier. We've been looking forward to the third installment of the so-called Cornetto trilogy since, well, probably t...Read More »
This is why Twitter is awesome. Yesterday, "Shaun of the Dead" director Edgar Wright went to his account to reveal that he shot a scene in the upcoming "Star Trek Into Darkness," the highly anticipated latest installation in the J.J. Abrams "Star Trek" reboot (read our review here). The uber-secreti...Read More »
Caravanning into theaters this weekend in limited release is Ben Wheatley's "Sightseers." It's easily one of the best films of the year so far and perhaps more importantly one of the most enjoyable. Our review of the film from Cannes last year affectionately dubbed it "Natural Born Campers," and tha...Read More »
And so it ends, and we're not just talking about the end of the world. Edgar Wright and his longtime friends and collaborators Simon Pegg and Nick Frost are finally putting the capper on their fabled, informally known Three Flavours Cornetto Trilogy. Starting with "Shaun Of The Dead" and continued w...Read More »
Edgar Wright's loose "Cornetto" trilogy is coming to an end. In a recent CapeTown Film Fest conversation (can someone please explain what "CapeTown" means? Is that code for nerd gathering?), Wright explained the origin of the ice cream jokes in his trilogy while discussing his latest film in the tri...Read More »
Focus Features will release two films this summer as counterprogramming aimed at the smart demo.Read More »
Something must be in the water (maybe it was the approaching Mayan apocalypse, which never happened), because end-of-the-world comedies are very much in vogue in 2013. There's Anna Kendrick and John Francis Daley in "Rapturepalooza," Seth Rogen and co in "The End Of The World," and indie "It's A Dis...Read More »


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Big Falls Trail is a 3.3 mile trail located near Forest Falls, California that features a waterfall and is rated as difficult. The trail is primarily used for hiking and is accessible from March until September.
heather ciccone (128)
1 month ago
This trail is beautiful. if you reach the waterfall at the top, it is pretty breathtaking. However, the rocks at the top are extremely slippery! Be careful. To get to the falls you have to leave the designated path and climb over large rocks and tree branches. It's worth the view, but can be dangerous, so be careful!
V Mahoney (73)
3 months ago
Trail to the base of the falls is relatively easy, although the footing is uneven in spots. There are forest service warnings against climbing the unstable cliffs to the top. Saw one injured guy coming down and chose to stop midway up the creek below the falls. Still was a nice little escape. Pick up an adventure pass at the general store on your way through town. With the low rainfall and snowfall this year, the falls are not very full and will likely be much lower this summer.
Kenny Kenny (61)
11 months ago
Nice hike, pretty easy hike to the first pool of water, if you go further, if becomes more difficult, plenty of boulders and rocks to climb and is somewhat steep. Once you make it to the big water fall, you have to climb a couple of boulders or walk in the water to get to it. If you choose to climb the boulders, be careful, they are kind of slick and very much so if your shoes get wet. Beautiful place, too bad taggers have vandalized the boulders.
Ahtollie Adarne (227)
1 year ago
went on this trail twice and enjoyed it very much. It's a short hike to the water but a very pretty one. You can get a great hike in if you go all the way to the top falls. be very careful as its steep and slippery. clean and beautiful, love this place.
LaRoy Montgomery (96)
1 year ago
Nice trail and views once you get to the big falls. Still need to be careful though while on the rocks. Saw a gentleman take a tumble yesterday and need paramedics to come.
Kelly Phillips (244)
1 year ago
Nice little hike. Go on a weekday.
Ryan Kerns (277)
1 year ago
Muddyface D'solis (272)
1 year ago
short hike amazing end but its more of climb than hike
Adam Schultz (607)
1 year ago
The falls are beautiful and climbing around on the rocks is fun. The actual trail is very short though. I would not go out of my way to visit, but if you are in the area, definitely check it out. The drive up can be a fun adventure in itself, as well. Check out El Mexicano nearby in Forest Falls for some good Mexican food.
Sofia Samarah (179)
1 year ago
The actual trail to the falls from the waterfall is very short, and very easy, but the actual falls are beautiful. Heading upward into the mountain is also fun but when we went it wasn't exactly a trail but a tried creek we walked up. Still such a fun adventure, and absolutely beautiful. Go on a weekday if you want to enjoy the falls. I've gone on a Wednesday and a Saturday and there were about three times more people on Saturday. Also be aware of wildlife, we saw a ram come down from the mountain and get very, very close to people.


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I just created a new
GEOMETRY column
p and need to populate values for all existing rows in the table for
p based on existing values in cols
lat and
Problem: Updating a single column using the query below works well because I typed in the
lat and
lng values manually. But when I want MySQL to update col
p for all rows in the tables, the query that I used does not set any values to col
p. I think it has to do with the sub-query (?), but I am not sure how to make it work properly. Thanks!
Query that works
UPDATE listings
SET p = GeomFromText('POINT(39.948177 -75.174324)')
WHERE listing_id = '585221';
Query that sets no value
Added a
WHERE clause so I dont destroy the entire table when testing. I actually want to do the
UPDATE query for ALL rows in the table
UPDATE listings
SET p = GeomFromText('POINT(lat lng)')
WHERE listing_id = '585221';


text:
'All they had to do was look for the hat'By JIM LITKE
The Associated Press | October 26,2012AP File Photo
Dallas Cowboys coach Tom Landry in 1975.There's a very good reason why coaches on NFL and college football sidelines this weekend are dressed exactly like the guys down at your car wash — or maybe it's the other way around.
There are actually 250 million or so rea$ons in the case of the NFL, and who knows how many more for college football teams, since most programs get to negotiate their own licensed apparel deal. It wasn't always like that, of course.
There are hats on the heads of more than half the coaches pictured in both halls of fame, as well as sports coats, ties and even the occasional bow tie completing the look. Some looked so distinct — Tom Landry of the Dallas Cowboys and Alabama coach Paul "Bear" Bryant come to mind — that even decades later, you could identify them just by seeing their profiles.
Not the current guys, though.
"Tommy thought it was important to look business-like, yet he would be the first one to tell you clothes don't win games," said Alicia Landry, whose late husband was arguably the best-dressed NFL coach ever. "But at the very least, the players always knew where he was with a glance. All they had to do was look for the hat.
"Nowadays, and I hardly watch any games, they all look the same to me," she added. "Except for that one coach who always wears his hood up."
That would be New England Patriots coach Bill Belichick, whose hoodie is on of the NFL's best sellers. But make no mistake — that has more to do with his success than his sense of fashion.
"The idea," NFL spokesman Brian McCarthy said, "is fans see it on Sunday and buy it on Monday. But most of our coaches would rather wear a golf shirt and windbreaker than a suit and tie, anyway. Besides, these guys are so good they could probably coach in pajamas."
Don't even think about it.
Next season marks the 20th anniversary of one of the NFL's most questionable decisions: requiring its coaches to choose their sideline wardrobes each season from a selection laid out by the league's official apparel manufacturer, currently Nike. The league gets its royalties, the coaches get a stipend and the rest of us get eyesores, like Rex Ryan in a Jets' sweater vest big enough to double as a tent or Green Bay's Mike McCarthy in a down jacket that makes him look like the Stay-Puft Marshmallow Man — in green.
The last coach to work the sideline in a coat and tie was former 49ers coach Mike Nolan in 2007. He thought it would be a great way to pay tribute to his father, Dick, who roamed the same sideline from 1968-75. The NFL originally said no because Reebok, its supplier at the time, offered neither a sport coat or tie in its line with the logo. After three years of petitions, Nolan and then-Jacksonville coach Jack Del Rio, neither of whom is a head coach today, both got to wear NFL-sanctioned versions.
"No one's asked since," McCarthy said, "but we'd look into accommodating them if it could be worked out."
Fat chance of that happening.
Dan Reeves, who played for the Cowboys and was Landry's assistant before coaching in Dallas, New York, Denver and Atlanta, was the last coach to routinely don a coat and tie for games. He was grandfathered in on the 1993 agreement, but switched to polo shirts when he arrived in Atlanta in 1997.
"The Smith family owned the team at the time, and when we negotiated a contract, it was part of the deal," he said. "They were dead last in merchandising sales at the time, so I understood. They were trying to get the people in the stands to start wearing the gear ...
"But I got into the habit because of Tom Landry and I kept with it because, I believe, the coat and tie calmed me down. I'd get all riled up and start pulling on the coat or the tie, and then I'd remember how stately and in control coach Landry always looked. So I wonder," added Reeves, "if that wouldn't help some of the guys out there right now."
If that doesn't work, maybe some of today's coaches should solicit fashion advice from the people they trust most.
Miami Hurricanes coach Al Golden's crisp white dress shirt and a sharp orange tie make him arguably the best-0dressed coach in the college game. He played for the late Joe Paterno at Penn State, himself one of the last throwbacks to the jacket-and-tie set. But when Golden got his first break as a head coach at Temple in 2006, he usually wore a sweat shirt.
One day he got a call. On the other end was his mom.
"Wear some pants and a shirt," she said.
Advice well worth heeding.
Jim Litke is a national sports columnist for The Associated Press. Write to him at email@example.com and follow him at Twitter.com/JimLitke.MORE IN Wire SportsWHITE SULPHUR SPRINGS, W.Va. For a change, Tiger Woods got off to a good start. Full StoryLONDON On the final point of the first set of his latest Wimbledon disappointment, Rafael Nadal... Full StoryMIAMI Dwyane Wade is staying with the Miami Heat. Full Story
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- RICHARD'S POOR ALMANACK: On this day 1739, 'Richard Palmer' identified in prison at York Castle as the notorious outlaw DICK TURPIN; IN 1836, Battle of the Alamo begins near San Antonio de Bexar, Texas; 1896, the Tootsie Roll invented by LEO HIRSCHFELD.
- RICHARD'S POOR ALMANACK: On this day in 1472, Orkney, Shetland islands put up as collateral by Norway to Scotland in lieu of dowry for MARGARET OF DENMARK on her marriage with JAMES III, king of Scotland; 1962, JOHN GLENN first American to orbit Earth.
- TOMORROW'S HEADLINES TODAY: City mayoral candidates debate campaign issues; Hartford, Conn., woman still missing; Neal Goswami reports attempts to legislate suicide; local woman loses 100 pounds through TOPS program.
- RICHARD'S POOR ALMANACK: On this day in 1878, JOHN TUNSTALL murdered near Lincoln, New Mexico, by the outlaw JESSE EVANS; in 1930, ELM FARM OLLIE first cow to fly in aircraft, first to be milked airborne; 1955, nuke test WASP; '79, snow in Sahara.
- TOMORROW'S HEADLINES TODAY: Rutland Herald News Editor Alan J. Keays and staff writer Gordon Dritschilo discuss stories planned for the February 18, 2015, edition of the newspaper: Winter budgets maxed, legal marijuana, Springfield bank job, USPS slowdown
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Angel of Grief
a Copy of the "Angel of Grief" a 1894 sculpture by William Wetmore Story which serves as the grave stone of the artist and his wife at the Protestant Cemetery, Rome.
This monument is for Jennie Roosevelt Pool, cousin of President Theodore Roosevelt
Challenge Entries
Original Crop www.flickr.com/photos/tkksummers/3324374321/
www.flickr.com/groups/fotocompetition/discuss/72157615745... Lost 2-2-3-5
Cypress Lawn Cemetery is located in Colma, CA.
as of December 2006, Colma had "1,500 aboveground residents ... and 1.5 million underground
Wow!! rgar is some headstone
The bridge
Seen on your photo stream. (?)
Hi, I'm an admin for a group called Angel of Grief, and we'd love to have this added to the group!
WoW ! ...
fantastic sculpture..
Thank you for sharing this beautiful picture under Creative Commons. I've used it in an article called Is it Possible to Have Unwavering Faith When Faced With Grief and Loss?
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GoWesty! Camper Products is a privately owned company specializing in parts, accessories, sales and service of Volkswagen (R) campers. It is not affiliated in any way with Volkswagen of America or Volkswagen AG. "Vanagon", "Bus", "VW", "Volkswagen", and "Eurovan" are registered trademarks and should be considered as such throughout our entire website.
Drive Nacho Drive: A Journey from the American Dream to the End of the World


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How Android Is Becoming the New Windows
It's more nuanced than you think. »
It's more nuanced than you think. »
Chrome: Flix Plus, a new extension from us at Lifehacker, adds new features and tweaks to Netflix.com, letting you filter its recommendations, remove spoilers, use keyboard shortcuts, and a whole lot more. »
Reading comics, particularly on tablets, is a delightful use of bright, vivid touchscreens. If you're a heavy reader and want to bring your own files, Astonishing Comic Reader is a relative newcomer with a ton of slick features. »
Researchers at the Italian Institute of Technology and Tokyo City University have taught a tiny humanoid robot to clean flat surfaces. The study is helmed by IIT's Dr. Petar Kormushev, who previously taught a disarmingly adorable robot to shoot a bull's eye with a bow and arrow all by itself. As you can see, the… »
We've all laughed at the classic cartoon gag where a bird flies headfirst into a window. Turns out this phenomenon isn't just a joke, it's deadly among migratory birds in Philadelphia, killing an estimated 1-5% of the migrating population. »
Iron Man! He's not just the kinda guy who saves the world from supervillains and Jeff Bridges with a shaved head anymore! No, now he's the kind of guy who's off crusading against... Linux? Wait, that can't be right. The latest interview promoting movie tie-in comic The Invincible Iron Man seems to suggest a more… »


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Carolina Hurricanes (8-12-8-1) at Vancouver Canucks (15-7-5-2), 10 p.m.
(Sports Network) - The Vancouver Canucks try to keep stockpiling points tonight when they welcome the Carolina Hurricanes to GM Place.
Vancouver has lost only once in the last seven games (3-1-3), having recorded nine of a possible 14 points in that time. The Canucks, with 37 points overall, sit one behind first-place Colorado in the Northwest Division.
On Thursday, the Canucks played to a 1-1 tie with the visiting Avs. Ed Jovanovski scored early in the third period to help Vancouver salvage the deadlock. Alex Auld stopped 27 shots for the Canucks, who are only three points behind Detroit in the race for the top spot in the Western Conference.
Auld played after being called up from the American Hockey League due to a groin injury suffered by regular backstop Dan Cloutier. Cloutier is listed as day-to-day.
Vancouver captain Markus Naslund did not register a point in the tie, but he enters today's action tied for second in the league with 36 points (15g, 21a). Naslund is even with Washington's Robert Lang and sits a point behind Detroit's Pavel Datsyuk in the scoring race.
Thursday marked the ninth time in the last 13 games that Vancouver has needed overtime (4-2-3).
The Canucks, 10-2-3 on home ice, will visit Nashville on Tuesday to kick off a three-game road trip.
Carolina, meanwhile, is just 1-2-1-1 in its last five tries, and has lost three of its last four away from home. On Thursday the Hurricanes were dealt a 1-0 loss by the Calgary Flames in the third slice of a four-game trip.
Miikka Kiprusoff earned his first shutout of the season and Shean Donovan scored early in the third period to lead Calgary.
Kevin Weekes had a solid outing, stopping 30-of-31 shots in defeat. Carolina, which was coming off a 3-2 win in Edmonton on Tuesday, has just six goals in its last five games.
The Hurricanes will return home and face Pittsburgh on Thursday.
The Canucks are 3-0-1 in the last four meetings with the Canes, and Carolina has lost four of its last five in British Columbia.


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The TSA-approved Luggage Locator "goes to sleep" when your plane takes off and "wakes up" upon landing. It tells you where your bag is (via text or e-mail), and even when it's headed your way on the carousel. Simply download the free app and pack it inside your suitcase. Works in every country except Japan and South Korea, in all bags except all-metal luggage. Compatible with iPhone 4S and newer models running iOS 7 and higher, and Galaxy/Android devices running Android 2.3 (Gingerbread) and higher. Includes one-year service subscription ($19.95 value).
See more details
Item # 203304
Track your checked baggage better than the airline! The TSA-approved Luggage Locator tells you your bag's location via e-mail or text message as soon as you land.
• Wireless luggage locator
• TSA approved device
• 100% safe and travel approved
• "Goes to sleep" when plane is in the air and "wakes up" upon landing
• Notifies you of its location via e-mail or a text message
• Works in every country except Japan and South Korea
• Works in all bags except all-metal luggage
• Includes free app for iOS or Android devices
• Includes one-year service contract
• Compatible with iPhone 4S and newer models running iOS 7 and higher, and Galaxy/Android devices running Android 2.3 (Gingerbread) and higher
• Tracks one suitcase at a time per device
• One device can be tracked by multiple phones if each phone has the app
• Multiple devices can also be tracked from the same phone (each suitcase must have its own device)
• Requires 2 alkaline AA batteries
PLEASE NOTE: This device requires a separate annual service charge ($19.95 per year). Your first year is included free with your purchase.
Length: 2.25
Width: 0.75
Height: 3
Weight: 0.25 Lbs
Please click here for the product manual.
Our Price: $89.99
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- Home
- Mining Safety Supplies
Mining Safety Supplies
Mines have unique safety and compliance needs, and our safety supplies can help businesses in the mining industry keep workers safe.
LabelTac® printers allow businesses in the mining industry create the safety labels needed to alert workers to hazards and provide instructions. The LabelTac® industrial labeling system has been proven to outlast other label makers on the market.
LabelTac® Printers can be used to print labels for hard hats, equipment, tools, lockers, PPE, machinery, racks, arc flash hazards, and general OSHA compliance requirements. Our label supplies are rain and moisture-resistant and are suitable for use in both indoor and outdoor conditions. With a LabelTac® printer you can print labels from 1/2" to 9" wide.
Glow-in-the-dark tapes, which provide eight hours of luminescence, last significantly longer than standard glow-in-the-dark tapes, making them suitable for use in mines. We also offer glow-in-the-dark signs to convey important safety messages in low-light conditions.
See the rest of our mining safety supplies below.


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Oriental Weavers Bali 4926 Outdoor RugItem # HN-OWS920
- Made of 100% polypropylene for a long life
- Available in various colors
- Machine-made rug with geometric theme
- Made in Egypt
- Your choice of size
Similar Area Rugs
Couristan Retrograde Galaxy Rug
$109.00 - $1,749.00
Kaleen Khazana Bali Rug - Ivory
$189.00 - $1,589.00
Momeni Baja Collection Indoor / Outdoor BAJ-8 Rug
$29.00 - $499.00
Oriental Weavers Karavia 1330X Outdoor Rug - Tan
$33.99 - $349.00
Surya Rain RAI-1093 Indoor / Outdoor Area Rug
$64.80 - $1,140.60
Couristan Recife Veranda Indoor/Outdoor Area Rug - Natural/Terra Cotta
$19.00 - $289.00
Reviewed by 1 customer
- Attractive Design
Best Uses
- Outdoors
Comments about Oriental Weavers Bali 4926 Outdoor Rug:
Wasn't sure about ordering this as it was described as blue--it's more of a soft gray with the brown and cream design elements as pictured. Very attractive. Not sure about durability or stain resistance because haven't had it long enough, thus the 4 stars. Came well packaged. Thought it might be difficult to get to lay flat but it settled down quickly when we weighted the edges for a few hours. Looks great on our balcony with our chocolate brown table and chairs as well as with some gray accent pieces we have.
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Automation Engineer Jobs in Surrey
Jobs 1 to 3 of 3
Automation Test Engineer
Surrey -
Spargonet Consulting Plc
Spargonet, an IT Services Company, requires exceptional Automation Engineer to join their bespoke development project team where they will work on project builds, write scripts and run Continuous Integration, TDD and Automation testing for our blue chip corporate clients... The teams are usually 3-8 people and run using SCRUM...
Salary: £50000 - £60000 per annum, Benefits Pension, 25 days holiday, Life andPosted: 2 days ago
C# Automation Test Engineer
Woking, Surrey -
Informatiq Consulting
C# Software Developer - opportunity to become an Automation Test Engineer !... A fantastic opportunity for an experienced C# Software Developer to be part of a leading financial software house, moving into an Automation Test Engineer position! This is a highly successful and award winning C# design and development team... The Automation...
Salary: £Excellent salary plus benefitsPosted: 4 days ago
Automation Test Engineer
Guildford, Surrey -
McGregor Boyall
You will be working with the latest "Big Data" and HTML 5 technologies alongside cutting-edge provisioning tools as they look to further extend automation capabilities. This is not a manual testing role... Owning the auto-deployment of product builds into QA... Strong experience and coding skills in Java... Extensive...
Salary: £40000 - £55000 per annumPosted: 2 days ago