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(Always read these instructions before the exercise.)
When designing a system, always read the relevant manuals and give sufficient consideration to safety. During the exercise, pay full attention to the following points and handle the equipments correctly.
[Precautions for Demonstration] WARNING
● Do not touch the terminals while the power is on, to prevent an electric shock. ● When opening the safety cover, turn the power off or conduct a sufficient check of safety before operation. ● Do not put your hand in the movable part.
● Follow the instructor's directions during the exercise. ● Do not remove the units of a demonstration machine or change the wiring without permission. Doing so may cause a failure, malfunction, injury and/or fire. ● Turn the power off before installing or removing a unit. Failure to do so may result in a malfunction of the unit or an electric shock. ● When the demonstration machine (X/Y table, etc.) emits an abnormal odor or noise, stop it by pressing the "power supply switch" or "emergency switch". ● When an error occurs, notify the instructor immediately.
1 MOTOR CHARACTERISTICS AT INVERTER DRIVE................................................. 1 1.1 Type of Motor ...................................................................................................... 1 1.2 Structure of Motor................................................................................................ 3 1.3 Basic Characteristics ........................................................................................... 4 1.4 Torque and Current Characteristics at Inverter Drive............................................ 8 1.5 Operating Standard Motor with Inverter ............................................................... 9 1.6 Standard Motor Output Characteristics in Inverter Operation ............................... 13 1.7 V/f Pattern and Torque Boost .............................................................................. 15 1.8 Load Torque Types and V/f Patterns ................................................................... 20 1.9 Acceleration/Deceleration Time and Inertia Moment J ......................................... 21 2. PRINCIPLE OF INVERTER AND ACCELERATION/DECELERATION CHARACTERISTICS ................................................................................................ 23 2.1 Configuration of Inverter ...................................................................................... 23 2.2 Operation of Converter ........................................................................................ 24 2.3 Principle of Inverter.............................................................................................. 28 2.4 Inverter Control Systems and Auto Tuning Function ............................................. 34 2.5 Protective Function .............................................................................................. 44 2.6 Acceleration/Operating Characteristics of Inverter ............................................... 49 2.7 Deceleration/Stop Characteristics of Inverter ...................................................... 53 2.8 Efficiency and Power Factor of Inverter............................................................... 56 3. CAPACITY SELECTION AND OPERATION METHOD FOR MOTOR AND INVERTER ................................................................................................................ 61 3.1 Capacity Selection ........................................................................................................ 61 3.2 Selection with Operation Pattern .................................................................................. 65 3.3 Effect of Machine Reduction Ratio................................................................................ 71 3.4 Capacity Selection Procedure....................................................................................... 72 3.5 Operation Method ......................................................................................................... 85 4. POWER SUPPLY OF INVERTER (HARMONICS AND INSTANTANEOUS POWER FAILURE) ................................................................................................... 99 4.1 Harmonics ........................................................................................................... 99 4.2 Rectifying Circuit and Characteristics of Generated Harmonics ............................ 100 4.3 Shunt of Harmonic Current .................................................................................. 101
4.4 Harmonic Suppression Guideline ................................................................................ 104
4.5 Influences of Harmonics to Peripheral Devices and Measures.............................. 113
4.6. Influence of an instantaneous power failure to the inverter .................................. 114 5 NOISE ....................................................................................................................... 120 5.1 Principle of Noise Generation .............................................................................. 120 5.2 Noise Types and Propagation Paths .................................................................... 121 5.3 Measures against Noise ...................................................................................... 124
5.4 Leakage Current ......................................................................................................... 132 5.5 Earth (Ground)..................................................................................................... 134
6. PROBLEMS IN THE USE OF INVERTER AND THE MEASURES ............................. 136 6.1 Environment and Installation Conditions ..................................................................... 136 6.2 Wiring of Inverter ................................................................................................. 145 7. PERIPHERAL DEVICES AND OPTIONS ............................................................... 153 7.1 Types of Peripheral Devices and Points to Understand ........................................ 153 7.2 Inverter Options ................................................................................................... 154 7.3 Power Supply Capacity ........................................................................................ 155 7.4 Moulded Case Circuit Breaker (MCCB)................................................................ 155 7.5 Earth Leakage Current Breaker (ELB) ................................................................. 156 7.6 Input Side Magnetic Contactor (MC).................................................................... 157 7.7 Surge Suppression Filter ..................................................................................... 159 7.8 Output Side Magnetic Contactor (MC).................................................................. 162 7.9 Thermal Relay (OCR) .......................................................................................... 162 7.10 Cable Size of Main Circuit.................................................................................. 163 7.11 Power Factor Improving Reactor (Either FR-HAL or FR-HEL)............................. 163 7.12 Inverter Setup Software ..................................................................................... 164 8. MAINTENANCE/INSPECTION............................................................................... 171 8.1 Precautions for Maintenance and Inspection ........................................................ 171 8.2 Inspection Items .................................................................................................. 171 8.3 Replacement of Parts .......................................................................................... 173 8.4 Measurement of Main Circuit Voltages, Currents and Powers .............................. 175 8.5 List of Alarm Display ........................................................................................... 177 8.6 Abnormal Phenomenon and Check Points........................................................... 180 8.7 Protective Function ............................................................................................. 184 8.8 Exercising with the Training Kit ........................................................................... 191
This chapter describes the basic characteristics to be focused on for performing the capacity selection or the operation when the squirrel-cage three-phase induction motor is driven by the inverter. The motor characteristics differ between the commercial power supply operation and the inverter operation. This is important for the user to understand.
POINTS for understanding!
1. Relationship between motor speed, current and torque 2. V/f (Voltage/frequency ratio) pattern and motor basic characteristics 3. Difference of motor characteristics between inverter operation and commercial power supply operation Torque, current, temperature, etc. 4. Concept of torque boost
1.1 Type of Motor
Although there are many methods to classify motors, the motors can be mainly classified into the following types when distinguished by the principle and structure. Within these motor types, the motor driven by the inverter is a mainly three-phase squirrel-cage motor. In addition, there is an energy-saving drive high-efficiency magnetic motor (IPM) for further energy saving.
Classification by power supply category DC motor Motor AC motor Induction type motor Squirrel-cage type motor Synchronous motor Wound-rotor motor SM (synchronous type) servo motor IPM motor Stepping motor 1-phase motor Classification by principle of operation Classification by structure
Deviation starting type motor Capacitor motor Repulsion starting type motor Indoor motor (Standard motor) Drip-proof protection type motor Totally-enclosed-fan type motor
3-phase motor
Constant torque motor Linear motor Explosion-proof type motor Geared motor, etc.
Table 1.1
Motor types Model Capacity Structure/ specification Drip-proof protection type Totally-enclosedfan type Totally-enclosedfan type Totally-enclosed strong cooling type Used in the environment with Explosion-proof type XF-E GM-S GM-D Geared motor GM-PJ GM-J MM-EF Synchronous motor IPM motor MM-CF MM-BF 0.4 to7.0kW 0.4 to 3.7kW 3.7 to 55kW 25 to 90kW 0.4 to 15kW GM-LJ 11 to 45kW 0.1 to 2.2kW 0.4 to 7.5kW 3.7 to 37kW For constant load For middle load For constant load or middle load For constant load Totally-enclosedfan type Totally-enclosed self-cooling More efficient than the induction type motor. High reliability improved with Large torque can be obtained at low speed. Used in various flammable gas, mist, etc. Approved by the Ministry of Most suitable for the applications to continuously operate with the rated torque at low speed. Application
Standard motor
0.4 to 55kW 0.2 to 55kW 0.2 to 55kW 0.2 to 55kW 0.4 to 22kW 0.4 to 45kW 30 to 45kW 55kW 0.2kW 0.75 to 7.5kW
Various speed controls can be performed in combination with the inverter.
Constant torque motor Induction type motor Explosion -proof type motor
Health, Labor and Welfare.
industries such as a transport machinery and a food machinery.
sensorless. High-speed operation is available.
1.2 Structure of Motor
Since the squirrel-cage motor is robust and has a simple structure, it can be used in various environments such as outdoor, underwater and explosive atmosphere. When the motor types are roughly classified by the structure, there are two types: the totally-enclosed-fan type and the drip-proof protection type. The structure example of the totally-enclosed-fan type is shown in Fig. 1.1. The structure is roughly divided into the fixed part and rotary part, and they are comprised of the machine part and electric part respectively. The external fan connected to the shaft is designed for cooling the heat generation of the motor itself. When the low-speed operation is performed by the inverter, the motor speed becomes slower and the cooling effect by the external fan decreases. To keep the rise of the motor temperature within the specified value, it is necessary to use the permissible load torque suppressed.
Frame External fan (for cooling) Stator core Rotor core Coil Bracket Bearing End ring fan
Terminal box
Center height
Fig. 1.1 Structure example of totally-enclosed-fan type motor
1.3 Basic Characteristics
1.3.1 Torque and current curve
The characteristics when the motor is directly started are shown in Fig. 1.2.
Current Start torque Is Torque T Maximum torque Tm Start torque Ts Motor current at load torque T L Motor speed [r/min] The motor rotates at a balancing point of the load torque and the motor generated torque. IM N
Area to be a generator
Balancing point of load torque and motor generated torque
Current [A]
Torque [N m]
Load torque TL
Synchronous speed No. Slip s
Fig. 1.2 Relationship of motor speed, current, and torque
1.3.2 Motor speed
The motor speed is determined by the number of poles and the magnitude of the power supply frequency to be applied in addition to the load torque. This is represented by the following formula.
120 Frequency f [Hz] Pole number P (1-S)
Motor speed N
Determined by the specification of the motor. This magnitude is called Synchronous speed N'O.
Determined by the load specification (load torque).
To change the motor speed, it is only necessary to change the power supply frequency to be applied to the motor or the number of poles as understood from the Formula (1.1). In addition to this, there is a method to change the applied voltage of the motor. To change the frequency................... Inverter To change the number of poles......... Pole number conversion motor To change the voltage ....................... PS motor (Primary voltage control) To change the slip ............................. Wound-rotor motor The variable speed motor (Mitsubishi AS motor) of the eddy current joint system has an electric joint of the eddy current system between the output shaft and the drive motor, and the drive motor always rotates at the rated speed. Since the motor speed of the output shaft is slipped at the joint part, it is similar to the system to change the slip S.
1.3.3 Slip
When the load is applied to the motor speed, it becomes a speed mismatched with (or reduced from) the synchronous speed in Section 1.3.1. The indicated degree of the gap with the synchronous speed is called "Slip". "Slip" is derived by Formula (1.2) as shown below.
Slip S
Synchronous speed No - Motor speed N Synchronous speed N o
(1) At a start (the motor speed is 0), the "slip" is 100%. (Normally it is indicated as "Slip 1".) When the frequency gradually increased with the inverter (called the frequency start), the "slip" is about a few percents. (2) For operation at the rated torque, the "slip" is generally 3 to 5%. When the load torque increases (overload), the "slip" and the motor current also increase. (3) When the slip becomes a minus value, it means that the motor speed has exceeded the synchronous speed (N&inequalityLN0).
Good to know for checking a motor
The torque generated from the motor is not fixed. When the load is small even if the motor capacity is large, the motor generated torque also becomes smaller proportional to the load. The motor generated torque constantly varies according to the load torque. The motor speed also varies according to the load fluctuation.
1.3.4 Motor current
As shown in Fig. 1.2, the faster the motor speed (i.e. the larger slip) is, the larger the current flows. When the current at slip 0 is the no load current, it may be approximately 50% of the rated current with a small capacity motor. Also for the minus torque (regenerative brake area), the larger the (absolute value of) slip is, the larger the regenerative current becomes.
Motor speed fluctuation and motor load current
The motor speed is determined by the relationship between the load torque TL and the motor generated torque as shown in Fig. 1.2. (1) When the load torque varies (constant motor torque) As the load torque increases, the motor speed (N2) slows down, and as the load torque increases, the motor speed (N1) becomes faster. Therefore, the larger the load torque is, the larger the motor current becomes.
N2 N1 Large TL Small TL [r/min] Output torque
Fig. 1.3 Load fluctuation and motor speed (2) When the motor applied voltage (power supply voltage) varies (constant load torque) Since the motor torque varies as the square of the voltage to be applied, the motor speed also varies when the voltage varies. When the voltage increases, the current decreases.
N2 N1 [r/min] High voltage Low voltage
Output torque
Fig. 1.4 Voltage fluctuation and motor speed
1.3.6 Rated motor torque
The "power" generated by the motor is called torque. Normally a "power" is represented as [N] in a linear operation. For the motor, however, the "power" is generated by turning the shaft. Therefore, the expression of "power" will be "Power in the rotational operation" = torque [N ▪m]. The value of the rated motor torque can be calculated by Formula (1.3).
Rated motor output P [kW] Rated motor speed N [r/min]
Rated torque TM
[N m]
Indicated on the name plates of motors or in test reports.
(Note) The "rated motor speed" is a motor speed at the rated motor torque when the rated voltage and frequency are applied.
What is the rated torque of 3.7kW 4P rated motor speed 1730 [r/min]? 3.7 Rated torque T M 9550 20.4 [N m] 1730
During the inverter operation, the calculation of the rated torque is not affected even if the synchronous speed N0 is used. For precisely calculating, use the rated motor speed.
Good to know for checking a motor
The rated motor torque is not a torque generated from the motor. It is a load torque which is permissible in the continuous operation at the rated motor speed.
1.4. Torque and Current Characteristics at Inverter Drive
The motor torque and current characteristics in the commercial power supply operation and the inverter operation are compared as shown in Fig. 1.5 [%] indicates the ratio to the rated torque and rated current. (Example: For four poles)
Commercial operation
Inverter operation
Speed and current curve
600 500 400 300 200 100 0 50Hz 60Hz 0 1500 1800 [r/min] ] Current [
] Current [
Is (Start current)
Overcurrent capacity of the inverter
150 100 0 0
15Hz 20Hz 30Hz 450 600 900
50Hz 60Hz 1500 1800 [r/min]
Speed and torque curve
300 250 ]
Torque [
Tm (Maximum torque)
Torque [
150 100 50 0 50Hz 60Hz 0 1500 1800 [r/min] Ts (Start torque) Rated torque
150 100 50 0 15Hz 20Hz 30Hz 0 450 600 900 50Hz 60Hz 1500 1800 [r/min] Rated torque
▪ The star torque (Ts) and start current (Is) are
both large. ▪ The motor speed is fixed by the power supply frequency.
▪ The operation starts from the low frequency, to suppress the start current, and the star torque is small. ▪ The motor speed can be set as desired regardless of the power supply frequency.
Fig. 1.5 Motor current and torque characteristics comparison (Example of V/f operation) Approximate characteristic values when a standard motor is used in the commercial operation (1) Start current (2) Start torque (3) Maximum torque (4) Slip at the rated load Is = 600 to 700 [%] Ts = 150 to 250 [%] Tm = 200 to 300 [%] S = 3 to 5 [%]
1.5 Operating Standard Motor with Inverter
1.5.1 Difference between the rated torque of 50Hz and 60Hz
For the use at any domestic place, the standard motor is designed with the specifications for the common use at the following three rating: 200V 50Hz, 200V 60Hz, and 220V 60Hz. The comparison of the rated current, motor speed and torque to each power supply specification for the commercial power supply operation with SF-JR 3.7kW 4P is shown in Table 1.2.
Table 1.2 Power supply 200V 50Hz 200V 60Hz 220V 60Hz
Comparison of common use 3 rated values Rated motor speed [r/min] 1420 1710 1730 Rated torque [N▪m] 24.9 20.7 20.4
Rated current [A] 14.6 14.2 13.4
When the rated current at each power supply rating is assumed to be I200/50, I200/60, and I220/60 respectively (I400/50, I400/60, and I440/60 for a 400V power supply), the following relationship exists and the current will be the maximum at 50Hz. I200/50>I200/60>I220/60(I400/50>I400/60>I440/60) As seen from Formula (1.3) in Section 1.3.6, the magnitude of the motor rated torque differs at 50Hz and 60Hz.
P [kW] N [r/min] P [kW] N [r/min] P 1500 P 1800
Torque at 50Hz
P Increased by 20
Torque at 60Hz
The motor current as well as the torque (power) is large at 50Hz, and the rise of motor temperature is also higher compared to at 60Hz consequently.
High temperature Low temperature
50Hz Large current
60Hz Small current
1.5.2 Singularity in the inverter operation
As compared to the commercial operation, the inverter operation has the "increase of motor current". Since the waveform of the voltage to be applied to the motor is not the sine wave but a wave pattern with distortion, the motor current at the rated torque increases by approximately 10% compared to that with the commercial power supply. Consequently, the motor temperature will be also higher than that with the commercial power supply. At this time, the problem is that when there is not enough margin to the specified value at 50Hz. This is why "Reduce the load torque to 85% at 50Hz" is indicated for the continuous operation in the catalog or instruction manual of the inverter. Since there is enough margin to the specified value of the temperature at 60Hz, the current fits into the specified value even if increasing.
Here, "at 50Hz" should not be considered the magnitude of the power supply frequency but "when the rated torque calculated with 50Hz is output".
1.5.3 For the voltage change when the speed is changed by the inverter
The motor speed can be changed by changing only the frequency as shown in Formula (1.1). However, if the output frequency is set to 50Hz or less with the constant voltage (e.g. 200V), the motor magnetic flux increases (or is saturated), and the increased current causes the motor to be overheated and then burned out. To prevent this, it is necessary to make the rule constant. Since the magnetic flux is proportional to the voltage and inversely proportional to the frequency as shown in Formula (1.4), this problem can be resolved by applying the voltage with which this relationship is always satisfied.
Voltage V Frequency f
Magnetic flux
In the case that the speed is set to a half (60Hz to 30Hz), V/f is as shown below.
V f
220 [V] 60 [Hz]
110 [V] 30 [Hz]
* Increased more for the voltage drop
compensation practice.
As above, the rise of the motor temperature can be avoided by changing the voltage. However, it is important to care about the torque status.
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1.5.4 Motor generated torque
The relationship between the motor applied voltage (V), the frequency (f) and the torque is represented by Formula (1.5).
Torque T
K: Constant
f I: Current
(1) If the ratio of V/f is constant, the torque is constant. (2) When the voltage (V) is constant and only the frequency (f) varies, the torque is inversely proportional to the frequency if the motor current is constant.
Constant torque Voltage proportional to frequency Reduced torque (constant output) Constant voltage
● The relationship between the voltage and the torque to
the change of frequency described as above is shown in Fig. 1.6. The relationship between the output voltage and output frequency of the inverter is called "V/f pattern". This is an important factor to control the motor.
Voltage V Torque T
Fig. 1.6 Constant torque and constant output range
1.5.5 Operation which exceeds 50Hz or 60Hz
Since the inverter output voltage cannot output more than the power supply voltage, the output voltage, which exceeds the frequency of 50Hz or 60 Hz (Base frequency…Refer to the following figure.), is constant. Since only the frequency is changed, the torque is reduced inversely proportional to the frequency if the motor current value is constant as shown in Formula (1.5). This area is called "constant output" range.
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Good to know for checking an inverter Base frequency
This frequency represents the frequency at the rated torque of the motor. Since the standard motor is designed for the use at either 50Hz or 60Hz, set the base frequency either 50Hz or 60Hz. Considering the rise of the motor temperature in Section 1.5.2, it is recommended to use the motor set at 60Hz regardless of the power supply frequency. For a machine of which motor rated torque is designed at 50Hz, the setting at 60Hz of the base frequency is also applicable if the load current at 50Hz is below 60Hz of the motor rated current. Fig. 1.7 V/f pattern and base frequency
Output voltage
50 60
Output frequency [Hz]
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1.6. Standard Motor Output Characteristics in Inverter Operation
The output characteristics for the combination of the Mitsubishi standard squirrel-cage motor (4 poles) and an inverter of the same capacity is as shown below.
Base frequency of the inverter. Not a power supply frequency.
220V 60Hz The rated torque of the output torque [ ] is 100 at 60Hz of the motor.
When increasing the boost at 3.7kW or less
200V 50Hz The rated torque of the output torque [ ] is 100 at 50Hz of the motor.
When increasing the boost at 3.7kW or less
Maximum torque of the factory default (boost setting value)
150 140
Continuous operation torque
Maximum torque of the factory default (boost setting value)
Output torque
Output torque
100 90 80 70 50 35 30
Short-time maximum torque
130 120
Continuous operation torque Short-time maximum torque
85 75
70 65
45 38 30 25 36 20 30 60 120 36 20 30 50 120
Output frequency [Hz]
Output voltage Output voltage
Output frequency [Hz] V/F pattern
V/F pattern
Fig. 1.8 Output characteristics of a standard motor (in V/f control) (1) The continuous operation torque is a permissible load torque which is regulated by the rise of the motor temperature. It is not the maximum value of the motor generated torque. (2) The short-time maximum torque is the maximum torque generated by the motor within the overload current rating (150%) of the inverter. Therefore, if the capacity of the inverter is increased, the maximum torque becomes larger. The short-time of the short-time maximum torque is the overload current permissible energization time and within one minute. * There is a constant torque motor, which is available for a continuous high torque operation at low speed, of which frame number is made larger by the inverter drive, and which is designed with the coil of which heat generation is suppressed.
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Good to know for checking an inverter
The standard motor can be operated at high speed of the maximum 120Hz. However, the usable frequency range is restricted depending on the motor size. For example, it is 120 Hz or less for up to the 4-pole 132 frame, 100Hz or less for 160 and 180 frames, 65Hz or less for 200 and 225 frames. It is restricted due to the bearing permissible speed and the structural strength of the motor depending on the motor size.
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1.7 V/f Pattern and Torque Boost
1.7.1 Fundamental equivalent circuit of motor
For your understanding of the torque boost, first the fundamental equivalent circuit of motor is described. Fig. 1.9 is an equivalent circuit which is generally used for a motor.
I1 r1 jx1 Im jx2 I2
Primary voltage Primary induced voltage Primary current Secondary current (primary converted value) Primary resistance Secondary resistance (primary converted value) Iron loss resistance Excitation reactance Primary magnetic leakage reactance Secondary leakage reactance Slip
rm V V'
r1 r2 rm Xm X1 X2 S
Fig. 1.9 Equivalent circuit of motor In addition, the equivalent circuit is as Fig. 1.10 in the condition that the circuit is open on the secondary side during the motor operation without load.
Im r1 jx1 Im △V rm V V'
Excitation current
Fig. 1.10 Equivalent circuit (secondary open without load)
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Voltage equation is as Formula (1.6). V'=V-(-jlm)(r1+jX1)...........................................................................................................................(1.6) If it is replaced with V=(-jlm)(r1+jX1), the formula can be simplified as Formula (1.7). V'=V- V .........................................................................................................................................(1.7) The torque generated torque affects due to the primary resistance and primary leak reactance inside the motor or the voltage drop caused by the cable impedance of the motor wiring.
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1.7.2 Torque boost
The output voltage of the inverter must be V/f = Constant at the base frequency or lower as shown in Section 1.5 (Fig. 1.11). However, the primary wiring of the motor includes the amounts of resistance and reactance (collectively called impedance) as shown in the equivalent circuit of Fig. 1.9., and the torque generated by the motor decreases due to the voltage drop caused by the impedance. A standard motor is designed with a winding in consideration for the amount of the voltage drop at 50Hz or 60Hz. When a standard motor is operated with an inverter, the voltage varies in proportion to the change of the output frequency f. Especially the voltage drop is large in the low-frequency range with low voltage, and the motor generated torque is extremely small compared to the one with the commercial power supply. Therefore, the decrease of the motor output torque is suppressed in the low-frequency range by increasing the voltage in the amount of &drtriangleV in Formula (1.7) to balance with the voltage drop. As shown in Fig 1.12, the compensation of the voltage in the amount of &drtriangleV is called torque boost.
torque boost V Base frequency Base frequency
Fig. 1.11 Ideal V/f pattern of motor The manual torque boost is as shown in Fig. 1.13.
Fig. 1.12 Actual inverter V/f pattern
Manual torque boost
V Base frequency f
Fig. 1.13 Manual torque boost The increase of the voltage is constant by f. (It is not relevant to the motor current.)
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1.7.3 Torque boost setting
When the large start torque or acceleration torque is necessary, the motor torque of about 100 to 150% can be generated in the low frequency area by adjusting the torque boost. (1) The standard torque boost (factory default) is adjusted to the characteristics of the Mitsubishi standard motor. (When the motor winding specifications are different as a special motor, it may be better to adjust the torque boost.) (2) If the torque boost is increased too much under light load, the current become rather large and the inverter may trip due to the overcurrent. (3) For the constant operation under light load, the motor efficiency is improved by reducing the torque boost. (Refer to Section 1.8 Reduced- torque load pattern.) (4) Likewise, the torque boost adjustment is effective against the voltage drop due to the cable between the motor and the inverter. The relationship between the motor torque and the current when the voltage is increased by the torque boost is shown in Fig. 1.14. Since there is a current limit (150% of the rated current) for the inverter drive, , the maximum value of the start torque is determined within the current range. If the torque boost setting value is too large, the current exceeds the limit and the overcurrent protection function is activated.
Torque [ ]
With the large torque boost
[ ]
With the standard torque boost
Torque boost 100
The current limit is exceeded
Current [ ]
150 100 50 4Hz 0 Motor speed[r/min] 6Hz
Current limit of the inverter
Load factor [
Fig. 1.14. Example of motor torque and current at a start
(Fig. 1.15 Example of load factor and motor current)
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When the torque boost setting value is increased, the change of the current for each load condition is as described below. 1) For the light load ........ Since the magnetic flux of the motor iron core is saturated, the current increases and the overcurrent protection function can be operated more easily. 2) For the heavy load ..... With the torque boost, the amount of the voltage drop caused by the motor primary winding and cable is compensated, and the large motor torque is generated. This reduces the motor slip, and the current decreases compared to that for the light load. (Refer to Fig. 1.15 Example of load factor and current)
Good to know for checking a motor
The inverter dedicated constant torque motor is a motor specially designed for the continuous use with 100% torque at low speed. When the motor is used under light load unavoidably, the motor current may exceed the rated motor current in the low-frequency range. Therefore, use the motor with reducing the manual torque boost.
How does the motor current change if the torque boost setting value of the inverter is increased? Although it differs depending on the load condition (light load or heavy load), the motor current increases by increasing the torque boost and the large start torque is generated. During the acceleration under heavy load, the motor slip decreases when the torque is increased. As a result, the average current during the acceleration can be suppressed. If the setting value is too large ,the overcurrent protection function is activated since the motor current right after the start exceeds the current limit.
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1.8 Load Torque Types and V/f Patterns
The load torque characteristics vary depending on applications. The following shows the typical examples and the V/f patterns to be applied. For the inverter operation, The V/f characteristics according to the load characteristics can be selected.
L o a d to rq u e ty p e
O u tpu t
T o rq u e
Frequency (motor speed)
T o rq ue
Frequency (motor speed)
T o rq u e
O u tp u t
O u tp u t
Frequency (motor speed)
Constant torque load
M a in a p p lic a tio n s
Reduced-torque load Fan Pump Blower
Constant output load Machine tool (main spindle drive) Winder (center drive)
Conveyor Cart Roll driving
Constant torque pattern
O u tp u t vo lta g e [V ]
Reduced-torque pattern
O u tp ut vo lta g e [V ] O u tp u t vo lta ge [V ]
Base frequency
Base frequency
Base frequency
Output frequency Hz T Constant: Torque constant load
Output frequency Hz
T/N2 Constant:Squarereduced- T N
Output frequency Hz Constant: Constant output load
torque load
Fig. 1.18 Load torque types and V/f patterns
Good to know for checking an inverter
When the reduced-torque load is operated, the V/f pattern of the constant torque can be used for the operation. However, the reduced-torque pattern is more efficient, provides the energy saving operation and can additionally expect the low-noise operation.
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1.9 Acceleration/Deceleration Time and Inertia Moment J
1.9.1 Acceleration/deceleration time
The acceleration/deceleration time differs between the commercial operation and the inverter operation as shown below.
Operation Acceleration/ Deceleration time
Acceleration time
ta Entire J 9.55 {TM (1.5 N 2) TL} [s] td
Deceleration time
Entire J 9.55 N TL [s]
Commercial operation
: motor speed [r/min] : Rated motor torque [N▪m] : Load torque [N▪m]
Entire J 9.55 (TM N TL) [s]
: Rated motor speed [r/min] : Load torque [N▪m]
Entire J 9.55 (TM N TL)
∆N : Difference of the motor speed
Inverter operation between before and after acceleration [r/min] TL : Maximum load torque [N▪m]
∆N : Difference of the motor speed
between before and after deceleration [r/min] TL : Minimum load torque [N▪m]
: Average acceleration torque ratio (Approximately 1.1 boost standard)
: Average deceleration torque ratio
(Regenerative control torque ratio)
Entire J = Motor JM + Load J L [kg ▪ m2]
(1) Depending on the difference of the average acceleration torque coefficient, the acceleration time for the commercial operation is shorter. (2) The motor coasts to stop for the commercial operation, whereas the motor stops with the regenerative brake activated for the inverter operation. Therefore, the deceleration (stop) time for the inverter operation is greatly shorter compared to that for the commercial operation. To suddenly stop the motor for the commercial operation, the mechanical brake is used. Alternatively, the DC dynamic brake or the electric brake method by reversed-phase breaking is adopted.
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1.9.2 Inertia moment J
(1) The inertia moment J is a numerical value of an object's inertia. A heavy object with a large diameter has a large inertia, and a light object has a light inertia.
Slow start Slow stop
Quick start Quick stop
(2) How to calculate the inertia moment J of a rotator
D [m]
1 8
Examples of the gravity
L [m]
Weight [kg] Gravity [kg/m3]
Aluminum Iron Cast iron
2.7 10 3 7.8 103 7.2 10
(3) For the calculation of the acceleration/deceleration time, the load inertia moment (JL) must be converted to the motor shaft. Motor shaft conversion J = J L i2(I = Reduction ratio)
(4) The load with large inertia moment J takes time to accelerate or decelerate. Therefore, the large motor torque is required to accelerate or decelerate in a short time. (5) The conversion formula of the inertia moment J and GD2 is expressed with the following formula. J= (1/4) GD2
- 22 -
This chapter describes the principle of how the basic circuits in an inverter operate to create variable frequency and variable voltage. These frequency and voltage are output from an inverter to a motor to change the motor speed. An inverter can be thought of as a power supply converter (converts from constant frequency/voltage to variable frequency/voltage) for motors. Although an inverter is powered from a commercial power supply, a waveform of the input current is different from that of a sine wave. Furthermore, the output waveform greatly differs from this input waveform. This discriminative waveform, which is generated due to the operation principle of an inverter, is highly relevant to the choice of a motor/peripheral devices and to the measurement of a current/voltage. For this reason, it is important to understand how the discriminative waveform correlates to the operation of each circuit in an inverter.
POINTS for understanding!
1. Principle of creating the output waveform (variable voltage/variable frequency) 2. Operation flow from start to stop 3. Concept of the inverter power factor
2.1 Configuration of Inverter
Fig. 2.1 shows the configuration of a general-purpose inverter, which uses a commercial power supply (AC 50Hz or 60Hz) to create an AC power supply that generates various, needed frequencies to rotate a motor at various speeds. More precisely, a general-purpose inverter consists of two significant sections, the main circuit and the control circuit. The main circuit is subdivided into the converter, which converts a current from a commercial power supply to DC and then smoothes pulsation included in the converted DC, and the inverter part, which converts the smoothed DC to AC with variable frequency. The control circuit controls the main circuit. Basically, a converter refers to a unit that performs forward conversion from AC to DC whereas an inverter refers to a unit that performs reverse conversion from DC to AC. However, with general-purpose inverters, the whole unit including the converter is referred to as an inverter. As described above, the main circuit part in an inverter consists of two power supply converters that are largely different from each other in elements and characteristics. The next section describes the individual principles of how the inverter part and converter part operate. Fig. 2.1 Configuration of inverter
AC power supply Converter part Main circuit Inverter part Inverter unit Motor IM
Control circuit
- 23 -
2.2 Operation of Converter
The converter consists of the following parts as Fig. 2.2 shows:
NFB 3 Inrush current limit circuit 1 Converter D1 D2 D3 R P +
1) Converter 2) Smoothing capacitor 3) Inrush current control circuit
AC power V supply
2 Smoothing E capacitor
Fig. 2.2 Converter circuit
(1) Principle of converter The following describes the waveform of an AC input current that is generated when creating DC from a single-phase AC power supply as shown in Fig. 2.3.
Voltage AC power supply V
Current I
D3 t1 t2 D1 D4 ON D3 D2 ON
Fig. 2.3 Principle of converter ▪ When a sine wave voltage with an effective value V (wave height 2 V) is input from an AC power
supply to the converter, the current flows through the diodes D1 and D4 only at t1, which has higher potential than the voltage E generated at the converter's output part (DC). ▪ In the half cycle where AC voltage is negative, the diodes D2 and D3 are conducted at t2, allowing a negative input current to flow to the AC side. This means that a waveform of the AC input current for the converter has changed from a sine waveform to a distorted waveform with harmonics.
- 24 -
Inverter part (load)
(2) AC input current in normal status (during motor operation) For the three-phase AC input, six diodes can be used in combination to rectify all the waveforms of the AC power supply. Doing so conducts the diodes in the respective timings as shown in Fig 2.4, allowing the input current to be in the same distorted waveform as created with the single-phase power supply. The diode-rectified waveforms of all the three phases are further smoothed to DC with less pulsation by the smoothing capacitor C. When the inverter is stopped, the DC voltage can be up to 2 times larger (approx. 280VDC with 200VAC) than the AC input voltage. Note that while an inverter is in operation the DC voltage slightly fluctuates depending on the output (torque/rotation speed).
S R T phase phase phase Input voltage (3-phase) DC voltage 0
D1 D2 Diode current D3 D4 D5 D6
Converter outp ut current
Output current (Without smoothing capacitor)
R phase
Current at D1 Current at D2 Current at D3 Current at D4 Current at D5 Current at D6
Smoothed DC voltage
Input current S phase
Fig. 2.5 DC smoothed waveform
T phase
Fig. 2.4 Principle of input current
- 25 -
Good to know for checking an inverter
When the three-phase AC input voltage becomes imbalanced, the AC input current may become significantly imbalanced. This is most likely to happen when a light load is used with a large DC bus voltage. A phase may open in an extreme case, and however this is not an error of the inverter. As the three phases of the inverter input current become imbalanced, compare the currents in all the three phases when measuring. To measure the DC bus voltage, measure the inverter terminals P+-N- with a tester. Be careful when measuring the DC bus voltage for 400V (200V) inverters. The voltage can be up to 800VDC (400VDC).
(3) AC input current at power on When an inverter is powered on, a large inrush current flows for charging a smoothing capacitor. To control the peak value of the inrush current, use the control resistor shown in Fig. 2.6. After the smoothing capacitor is charged, short the both ends of the control resistor with a relay, etc.
R Control resistor I Charging current C Smoothing capacitor N P
Fig. 2.6 Inrush DC control resistor
Without inrush current control circuit I The peak value is large. With inrush current control ci rcuit I The circuit makes the peak value smaller and prevents the converter module from being damaged.
Approx. 50ms
Fig. 2.7 Inrush current
- 26 -
Do not switch an inverter between on and off too often with a magnetic contactor (MC), etc. Doing so lets the peak current to flow to the converter every time the inverter is switched, shortening the lives of the diodes. It may also shorten a switching life of the inrush current control circuit, and therefore the number of switching times should be limited within several times a day. The purpose of the converter part is to create DC power supply. Apply the base current to a transistor to rotate a motor. (Turn the control start input terminal STF or STR on.)
Charging current DC voltage inrush current Power supply voltage
Fig. 2.8 Actual measurement example of inverter input current/voltage waveform
- 27 -
2.3 Principle of Inverter
(1) Method to create AC from DC An inverter is a device to create the AC from the DC power supply. See the basic principle with the single-phase DC as the simplest example. Fig. 2.9 shows the example of the method to convert the DC to the AC by utilizing a lamp for the load in place of a motor. If the four switches S1 to S4, which are connected to the DC power supply, are alternately turned on/off, the AC is created as shown in Fig. 2.10.
Switch S1
Switch S3 Lamp
DC power + supply -
+ A Switch S2 Switch S4 L
0 -
Fig. 2.9 Method to create AC
Fig. 2.10 Current waveform
▪ When the switches S1 and S4 are turned on, the current flows in the lamp L in the arrow A direction. ▪ When the switches S2 and S3 are turned on, the current flows in the lamp L in the arrow B direction. Therefore, if the switches are alternately turned on/off with the combinations of the switches S1 and S4 and the switches S2 and S3, the AC is created since the direction of the current flowing in the lamp L alters. (2) Method to change frequency The frequency is changed by changing the period to turn on and off the switches. For example, if the switches S1 and S4 are turned on for 0.5 second and S2 and S3 for 0.5 second and this operation is repeated, the AC with one alternation per second, i.e., the AC with a frequency of 1[Hz] is created.
0.5s S1,S4 ON S2,S3 ON 0.5s
Fig. 2.11 1Hz AC waveform
- 28 -
Generally, under the condition that S1/S4 and S2/S3 are turned on for the same period of time and that the total time of one cycle is t0 seconds, the frequency f can be obtained as follows:
f =
1 t0
Fig. 2.12 Frequency (3) Three-phase AC Fig. 2.13 shows the basic circuit of a three-phase inverter.
S5 U Motor
60 120 180 240 300 360 420 480 540
DC power + supply E -
Fig 2.13 Three-phase inverter basic circuit Turn on/off the switches S1 to S6 in the order shown in Fig. 2.14. Doing so obtains pulse waveforms at sections U-V, V-W and W-U in the same cycle, and applies AC voltage in a rectangular waveform to a motor. Changing the on/off cycles of the switches outputs a needed frequency to a motor, and changing the DC voltage E changes the input voltage at the same time. (4) Configuration of inverter part Instead of switches, six transistors are used as shown in the configuration of Fig. 2.15. The connected motor is a three-phase motor, and this motor is rotated by turning the transistors on/off alternately. To change the motor rotation direction, change the order that the transistors are turned on/off.
Fig. 2.14 Method to create hree-phase AC
+ 3-phase AC
IM Motor
Fig. 2.15 Transistor inverter
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Good to know for checking an inverter
If an AC power supply is applied to the output terminals of the inverter part, an inrush current flows for charging the smoothing capacitor C through the diodes that are connected in parallel with the transistors, as mentioned in Fig. 2.7. In this example, control resistors are not installed in the circuit on the transistors side and therefore the diodes of the transistor section will be damaged. Never connect the power supply to the output terminals U, V and W of the inverter.
(5) Role of transistors A transistor is composed of three terminals, a collector (C), emitter (E) and base (B) (substituted by a gate (G) in IGBT.). The line C-E is not conducted (switched off) when a base signal is off, and conducted (switched on) when a current is applied to the base. In other words, transistors function as the switches S (ON-OFF) with faster operation. To turn off this base signal (substituted by a gate signal in IGBT.) is referred to as "transistor base shut-off", which appears in the explanation for the protective function of the inverter. When the transistor base shut-off is performed, the six transistors are turned off simultaneously, disconnecting the inverter from the motor. In other words, the motor coasts to stop. (6) Methods to change AC voltage To rotate a standard motor through an inverter, it is necessary to change voltages according to the V/F pattern as described in "MOTOR CHARACTERISTICS AT INVERTER DRIVE". The control system of general-purpose inverters is referred to as "voltage source" system since the inverter part is their voltage source. The voltage source system is subclassified into the following types in accordance with the voltage change method. Fig. 2.16 Transistor
S B E G E Switch Transistor C IGBT C
Voltage source
...... System to control the voltage applied to a motor
PAM system
...... System to change the DC voltage
PWM system
...... System to change the switching pulse w idth of a transistor
Sine wave approximation PWM system
...... System to change the switching pulse width of a transistor so that the shape of
an output average voltage waveform approaches the shape of a sine waveform
- 30 -
Differences between these control systems affect motor characteristics (vibration, noise, torque ripple, motor current ripple, torque response level, etc.). (Refer to Table 2.1)
Table 2.1 Control systems for voltage source inverters (E: DC voltage) Control system Output frequency Low (low voltage) Output frequency High (high voltage) Characteristics ▪ Low motor noises ▪ Low noise ▪ High efficiency ▪ Converter is required for voltage control. ▪ Low response speed ▪ Smooth operation not possible at low speed ▪ Frequency/voltage contro by the inverter part alone ▪ Harmonic noises from a motor
PAM system (PAM: Pulse Amplitude Modulation)
PWM system (PWM: Pulse Width Modulation)
Output voltage waveform Output average voltage E E
Output voltage waveform
Sine wave approximation PWM system
Output average voltage E E One carrier
▪ Smooth operation at low speed ▪ Lower cost than PAM ▪ Low-degree high-frequen is less. ▪ Harmonic noises from a motor
The PWM system is a system that changes the output voltage by generating switching pulses within one cycle and changing the pulse width. The sine wave approximation PWM system is a system that makes the average output voltage shape a sine wave by changing the switching pulse width within one carrier. Most of general-purpose inverters use the sine wave approximation PWM system. The number of switching pulses generated per second is referred to as carrier frequency. With the PWM system, the frequency components of the generated motor vibration and motor noise are proportional to the carrier frequency. If there is a reference saying high carrier frequency PWM control, this means that the carrier frequency is high. Also note that the Soft-PWM control is a control system that suppresses the increase of generated noise and reduces the motor magnetic noise by preventing the carrier frequency from being higher and dispersing the components of the motor magnetic noise.
- 31 -
Good to know for checking an inverter
If a machine generates large vibrations and noises only within a specific motor speed range, the cause may be a resonance with the carrier frequency. With the Mitsubishi general-purpose inverter FREQROL-A700 series, these vibrations and noises may be reduced by changing the carrier frequency pattern (parameter 72 "PWM frequency selection"). Also note that doing so changes the motor noise sound. The high carrier frequency is higher than the human audible frequency range. Therefore the electromagnetic noises are hardly heard from a motor, realizing the low noise rotation. However, transistors used in the inverter part are normally limited for use at approximately up to 2kHz. For this reason, recently IGBTs (Insulated Gate Bipolar Transistor) are used more commonly.
Good to know for checking an inverter
Lower noise operation may result in a larger leakage current between the inverter and the motor. Pay attention when selecting an earth leakage current breaker and be careful when earthing (grounding).
- 32 -
Output current waveform
Output voltage waveform
Fig. 2.17 Measurement example of the inverter FREQROL-A700 series output current/voltage waveform (at 40Hz)
Fig. 2.18 Measurement example of the inverter FREQROL-A700 series output current/voltage waveform (500% of Fig 2.17) (at carrier frequency 2kHz)
- 33 -
2.4 Inverter Control Systems and Auto Tuning Function
2.4.1 V/F control
changed in the constant ratio (V/f) as shown with the dotted line in the figure below. For this reason, this system is called V/F control. In this system, the voltage to be actually valid decreases due to a voltage drop in a wiring or the primary coil of a motor, and enough amount of torque cannot be output. The slower the speed is, the more this phenomenon affects. (Low-speed torque becomes insufficient.)
Torque boost V/f=Constant
All models
With conventional general-purpose inverters, when f (frequency) is changed, V (output voltage) is
Therefore, the amount of voltage drop estimated in advance is set higher (torque boost *) as indicated with the solid line in the figure to cover the shortage of the torque at low speed. * As described in Section 1.7.3, when the torque boost is increased too much, the sufficient torque is provided securely. However, it may cause overcurrent to be generated, and the inverter is likely to have an OCT (overcurrent) trip. To solve this, there are other control systems available such as the real sensorless vector control, advanced magnetic flux vector control and general-purpose magnetic flux vector control.
Frequency f
Voltage V
Fig. 2.19 V/F control
- 34 -
2.4.2 General-purpose magnetic flux vector control
This control divides the inverter output current into an excitation current and a torque current by vector calculation and makes voltage compensation to flow a motor current which meets the load torque. By this, the low-speed torque can be improved and a high torque of 200% can be obtained at 6Hz. Even if the motor constant becomes somewhat unstable (due to use with other manufacturer's motors), large, stable low speed torque can be provided without any special settings of a motor constant or tuning. This feature realizes the wide versatility. ● Based on the output frequency and each current inverter output current (motor current) into an excitation current (a current necessary to generate a magnetic flux) and a torque current (a current proportional to the load torque) by vector calculation. (Refer to the figure on the right.) ● When a motor current is changed due to the load fluctuation, the amount of a voltage drop on the primary side of the motor (including the wiring) is changed. This affects the amount of the excitation current. The amount of the voltage drop is calculated from the motor and primary wiring constants and the magnitude of the torque current. By this, the output voltage from the inverter is compensated (increased or decreased) so that the primary magnetic flux of the motor stays constant. ● A motor constant necessary for the calculation is preset to the inverter. The remaining task to perform the general-purpose magnetic flux vector control is just to set a motor capacity.
Excitation current
Torque current
phase to the output voltage, this control divides the
Motor current
Fig. 2.20 General-purpose magnetic flux vector control
- 35 -
General-purpose magnetic flux vector control
3Hz 6Hz
Conventional V/F control
Load torque(%)
Load torque(%)
300 200 100 0 -100 -200
300 600 900 1200 1500 1800 10Hz 20Hz 30Hz 40Hz 50Hz 60Hz
300 200 150 100 0
3Hz 60Hz
50Hz 10Hz 90 300 30Hz 900 1500
Motor speed (r/min)
-100 -150 -200
Motor speed (r/min)
Fig. 2.21 Example of speed-torque characteristics during general-purpose magnetic flux vector control
- 36 -
2.4.3 Advanced magnetic flux vector control
This control divides the inverter output current into an excitation current and a torque current by vector calculation and makes frequency and voltage compensation to flow a motor current which meets the load torque. By this, the low-speed torque and speed control range can be improved, and a high torque of 150% can be obtained at 0.5Hz. ● Based on the output frequency and each current phase output current (motor current) into an excitation current (a current necessary to generate a magnetic flux) and a torque current (a current proportional to the load torque) by vector calculation. (Refer to the figure on the right.) ● The actual motor speed is estimated based on the torque current, and the output frequency is compensated (increased or decreased) so that this estimated speed becomes the preset speed. <<Slip compensation>> ● When a motor current is changed due to the load fluctuation, the amount of a voltage drop on the primary side of the motor (including the wiring) is changed. This affects the amount of the excitation current. The amount of the voltage drop is calculated from the motor and primary wiring constants and the magnitude of the torque current. By this, the output voltage from the inverter is compensated (increased or decreased) so that the primary magnetic flux of the motor stays constant. The portions highlighted in gray are the features added to the general-purpose magnetic flux vector control. These additional features allow a large torque to be generated at lower speed. Also, the auto tuning function allows an inverter to measure and store the motor circuit constant. With this feature, the inverter can perform highly accuracy calculation and supports wider speed control ranges.
Excitation current
Torque current
to the output voltage, this control divides the inverter
Motor current
Fig. 2.22 Advanced magnetic flux vector control
- 37 -
Advanced magnetic flux vector control Load torque(N m)
40 20 0 -20 -40
6Hz 200 400 600 30Hz 800 1000 1200 1400 1600 60Hz 1800
Conventional V/F control
出力周波数 200% torque (HZ)
100% torque
Load torque(N m)
40 20 0 -20
3Hz 1Hz
10Hz 300
30Hz 900
50Hz 60Hz
200% torque 100% torque speed (r/min)
1800 Motor
Motor speed (r/min)
Fig. 2.23 Example of speed-torque characteristics during advanced magnetic flux vector control
Item The number of motors in combination use Standard motor Motor available for Constant torque combination motor Inverter capacity available for combination Supported model Speed control range (at driving) Advanced magnetic flux vector control 1:1 General-purpose magnetic flux vector control 1:1 Two-pole, four-pole, six-pole Four-pole
Two-pole, four-pole, six-pole Four-pole
Same as or one rank higher than the motor capacity
- 38 -
2.4.4 Real sensorless vector control
This control divides the inverter output current into an excitation current and a torque current by vector calculation and controls frequency and voltage optimally to flow a motor current which meets the load torque. By this, the low-speed torque, speed control range and speed response can be improved, and a high torque of up to 200% (3.7kW or less) can be obtained at 0.3Hz. ▪ This control uses the estimated speed, which is calculated from the motor current and output voltage, as a speed feedback value. Also, this control has the current control loop as the vector control does, which separately allows the calculations for a necessary excitation current (a current necessary to generate a magnetic flux) and a torque current (a current proportional to the load torque).
Excitation current
Torque current
Motor current
By controlling a torque current, responses to load changes become faster (fast response). Also, by issuing torque commands, the torque control is possible. Using the real sensorless vector control, high accuracy/fast response speed operation by the vector control can be performed with a general-purpose motor without encoder.
Output torque(%)(60Hz reference) Example of torque characteristics data Torque(%) Example of torque limit characteristics
Motor speed Torque being limited
Fig. 2.24 Real sensorless vector control
Short-time maximum torque (0.4 to 3.7K) 200 Short-time maximum torque (5.5 to 500K) 150 Continuous torque (0.47K)
100 95 70 50 0 0.3 3 6 60
Motor generated torque
120 0 0
Output frequency (Hz)
Fig. 2.25 Torque characteristics example For the motor SF-JR4P (with 220V input)
Fig. 2.26 Torque limit characteristics example For the motor SF-JR4P 3.7kW
- 39 -
Motor speed(r/min)
Item The number of motors in combination use Standard Motor motor available for Constant combination torque motor Inverter capacity available for combination Supported model Speed control range (at driving) Speed control Torque control Position control
Real sensorless vector control 1:1 Two-pole, four-pole, six-pole Four-pole
Advanced magnetic flux vector control 1:1 Two-pole, four-pole, six-pole Four-pole
Same as or one rank higher than the motor capacity
- 40 -
2.4.5 Vector control
This control is a system which divides the inverter output current into an excitation current (a current necessary to generate a magnetic flux) and a torque current (a current proportional to the load torque) by vector calculation and controls a frequency and voltage optimally to flow a necessary current individually according to this load magnitude. The vector control has the current control loop, which separately allows the calculations for a necessary excitation current and a torque current. By controlling a torque current, responses to load changes become faster (fast response). Also, by issuing torque commands, the torque control is possible.
Detect a motor speed with an encoder and calculate a motor slip to identify the load magnitude.
Torque current
Motor current
Excitation current
Fig. 2.27 Vector control
To accurately calculate them, when using the vector control, use a dedicated motor featuring stable constants with an encoder featuring high accuracy. For the vector control, a standard motor can also be used with an encoder installed on it. However, torque control is less accurate in such case.
150% 100%
Short-time rating (1 min)
75% 50% 3000
Continuous operating range Motor speed r/min (This example is based on a dedicated motor of 1.5K to 22K.)
Fig. 2.28 Example of vector control dedicated motor output characteristics Item Motor Encoder Speed control range (at driving) Parameter setting Response Speed control Torque control Position control
Fig. 2.29 Appearance of vector control dedicated motor (SF-V5R) Vector control Dedicated motor, standard motor Required 1:1500 Not simple (detailed data required)
Real sensorless vector control Standard motor Not required 1:200 Simple
dt k
- 41 -
Real sensorless vector control The vector control is a system that rotates and controls a dedicated squirrel-cage motor with an encoder or a standard squirrel-cage motor with an encoder in virtually the same manner for rotating and controlling a DC motor. On the other hand, the real sensorless vector control is a system developed to rotate a standard squirrel-cage motor in the condition similar to that for the vector control. Features of the real sensorless vector control system (1) In the vector control, the motor speed of the rotor is detected by the encoder installed at the shaft end and therefore the motor speed detection can be made accurately. On the other hand, in the real sensorless vector control, the motor speed of the rotor is estimated based on the motor voltage and current. This is why the detection is less accurate, but a standard motor can be used. (2) The real sensorless vector control is applicable for the applications such as to minimize speed fluctuation, needs for low speed torque, to prevent machine from damage due to too large torque (torque limit), and torque control. Note that with a severe load fluctuation, systems may become unstable for some equipment. In such cases, use the advanced magnetic flux vector control. Also note that speed cannot be estimated at nearly 0Hz of the output frequency. To perform torque control in the low speed region or at a low speed with light load, perform the vector control using an encoder.
- 42 -
2.4.6 Auto tuning function
With this function, an off-line inverter itself measures and stores motor circuit constants necessary for rotating in the general-purpose magnetic flux vector control, advanced magnetic flux vector control, real sensorless vector control and vector control. More precisely, by turning the auto tuning command on, an inverter outputs the motor excitation signal with certain conditions. From values obtained at this time, such as a value of the current that flew, the inverter internally calculates the motor resistance values r1/r2, inductance values L1/L2/M, etc. and then saves them to the memory. Note that in the general-purpose magnetic flux vector control, the motor resistance value r1 is calculated inside the inverter.
r1 L1 M (1-S)r2 S L2 r2 r1:Primary resistance r2:Secondary resistance L1:Primary inductance L2:Secondary inductance M :Excitation inductance
(1-S)r2 S
:Mechanical output equivalent resistance
Fig. 2.30 Equivalent circuit of an induction motor ● An inverter itself measures the motor constants even with a special motor or other manufacturer's motor. This extends an application range and improves ease of use. ● The accurate measurement of the motor constants allows starting torque and low-speed torque to be improved. ● Wiring lengths of over 30m are supported by the advanced magnetic flux vector control, real sensorless vector control and vector control. ● Two types of the off-line auto tuning modes (FREQROL-A700 series) are available, and the tuning that matches your machinery can be performed. ▪ Simpler and quicker constant measurement without motor rotation ▪ Better magnetic flux vector control by more accurate constant measurement with motor rotation ● Online auto tuning (FREQROL-A700 series) By quickly tuning the motor status at a start, high accuracy operation unaffected by the motor temperature and stable operation with high torque down to ultra low speed can be performed.
- 43 -
2.5 Protective Function
2.5.1 Purposes and types of protective functions
An inverter provides various protective functions whose purposes are largely classified into those to "protect the inverter" and those to "protect a motor from overheat". In addition to the protective functions, an inverter is equipped with alarm functions to inform that the operation status is abnormal. The following explanations are made based on the FREQROL-A700 series inverter.
Inverter protection Overcurrent shut-off During acceleration OC1 At constant speed OC2 During deceleration OC3 Regenerative overvoltage shut-off OV1 OV2 OC1 GF OV3 OC2 OC3
Output side short (short between cables) Instantaneous power failure Protection Undervoltage UVT 10H BE IPF
Output side earth (ground) fault overcurrent
Inrush current control circuit error Brake transistor error detection Overload Motor overheat protection THT FIN OLT PTC
Heatsink overheat Overload THM
PTC thermistor operation Others
External thermal relay operation Plug-in option connection error Storage device error Retry count excess Output phase failure Input phase failure CPU error CPU PE RET LF ILF E6 E7 Parameter unit disconnection
OHT OPT OP3 E1 to 3
24VDC power supply output short circuit Operation panel power supply short circuit Brake sequence error
MB1 to 7
Output current detection value excess Communication error Analog input error SER USB AIE
Opposite rotation deceleration error Internal circuit error Alarms The cooling fan is faulty. The operation status is abnormal.
Operation stop notification
Fan failure FN Overcurrent stall prevention (during acceleration, OL at constant speed, during deceleration) Overvoltage stall prevention (during deceleration) oL PU stop PS TH RB rE1 to 4 Electronic thermal relay pre-alarm Regenerative brake duty pre-alarm
Er1 to 4 MT
Maintenance signal output Parameter copy
Speed limit display
- 44 -
2.5.2 Mechanism of protective functions
Inverter (FREQROL-A 700 series) NFB R
Power supply
Converter part
Inverter part CT C R CT U V
OCR Motor IM
External thermal relay operation Voltage detection Regenerative overvoltage shut-off Undervoltage Stall prevention Current detection Overcurrent shut-off Output side short circuit Output side earth (ground) fault overcurrent Overload (electronic thermal relay) Stall prevention OH SD
Power supply voltage detection Instantaneous power failure protection
Brake transistor conduction detection Brake transistor error detection
Connection error
Plug-in option Connector
Contact output
Fan failure Rotation detection Cooling fan
Open collector output
Fig. 2.31 Protective functions related circuit
- 45 -
2.5.3 Current/voltage level at which protective functions operate
The protective functions operate when the detected current or voltage is at the level shown below.
Current Approx. 200% Inverter output shut-off current "Overload" inverse time characteristics "Stall prevention" 150% operation current (*1) (Factory default) DC voltage
Voltages indicated in parentheses are those of 400V series.
Approx.400V Inverter output shut-off voltage (Approx.800V) Approx.385V "Stall prevention" operation voltage (Approx.770V) Built-in brake operation voltage Approx.370V (FREQROL-A700 series of 22K or less) (Approx.740V) No 30K or higher (*2) Approx.215V "Undervoltage" operation voltage (Approx.430V)
100% Rated inverter output current
(*1) Replaced by changed operation current (%) (*2) Approx. 150V (Approx. 300V) in the AC input if the operation current level is changed. voltage
Good to know for checking an inverter
A regenerative overvoltage shut-off (OV1 to OV3) is a phenomenon that occurs only when a regenerative power from a motor is large. Note, however, that an inverter occasionally trips while a motor is at stop due to overvoltage. This phenomenon occurs in the following process: surge voltage is applied from the power supply side, the smoothing capacitor is charged, and the voltage level reaches the output shut-off voltage level. The most possible source of this phenomenon is the switching operation of the power factor adjustment capacitor in the power supply system (high or low pressure). To avoid this phenomenon, install an AC reactor (or power factor improving reactor).
- 46 -
2.5.4 Display and output signals when protective functions operate
Protective function operates Display
The alarm definitions are displayed on the parameter unit display.
Output signals
The alarm output (contact signal) is turned on. The open collector output (IPF) is turned on at an instantaneous power failure. Displayed at the right end of the parameter unit display (OL).
Alarm function operates
Display Output signals
The error output (contact signal) is not turned on. The open collector output (OL) is turned on when the stall prevention is operated. If the parameter is preset, the open collector output is turned on when pre-alarm is operated.
Parameter unit FR-PU07
Operation panel FR-DU07
Error/alarm display
Fig. 2.32 Display example at error occurrence
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2.5.5 Reset method
(1) When a protective function operates, the parameter unit indicates an error on its display and the inverter outputs an alarm signal to disable its outputs. (2) Reset the inverter to restart it. The inverter holds the abnormal status until reset. Follow the procedure below to reset the inverter. 1) Short the reset terminals RES-SD, which are provided with the inverter, for 0.1 second or longer, and then open the terminals. (The inverter cannot be restarted with the terminals shortened.) 2) Open the power supply terminals (R, S, T) once, wait 0.1 second or longer, and then close them. 3) Use the inverter reset function provided in the help functions of the parameter unit. 4) Press the RESET key of the parameter unit (operation panel).
The protective function operates. Inverter output Motor speed Coasting to stop t Output shut-off Output stop hold t t t t
Alarm output signal terminals Across A-C Reset signal terminals Across RES-SD Start signal terminals Across STF-SD
Fig. 2.33 Timing chart of the reset operation
Good to know for checking an inverter
If the reset is performed with the inverter while the motor is rotating, the transistor base shut-off is performed, and then the motor starts coasting. If the reset signal is turned off, the motor, which is currently coasting, restarts rotating (the inverter restarts from the starting frequency). This may cause an overcurrent trip. For this reason, do not reset the inverter while the motor is rotating.
2.5.6 Retry function
When an alarm occurred in an inverter, if the retry function is enabled, the inverter can automatically reset the alarm, restart and continue the operation. When this function is selected, stay away from the inverter as it will restart suddenly after an alarm stop.
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2.6 Acceleration/Operating Characteristics of Inverter
2.6.1 Start
Input the inverter start signal (turn on the terminals STF-SD or STR-SD) and the frequency command signal to the inverter. Then the inverter outputs the starting frequency, and the motor generates torque. If the motor start torque in the starting frequency is larger than the load start torque, the motor starts rotating. If the load torque is larger than the motor start torque, the motor stays locked. In such a case, increase the output frequency gradually. The motor starts rotating when the motor start torque exceeds the load torque TL as shown in Fig. 2.34. Note that high motor starting frequency generates a large motor lock current. If this current exceeds the current limit, overcurrent (OC1) or overload (THT) may occur, resulting in a trip.
Current [%] Torque [%] 100 80 50 6Hz 4Hz 0 150 100 50 0 4Hz 6Hz 8Hz Motor speed [r/min] Current limit of the inverter 8Hz TL
Fig. 2.34 Start torque
When a motor is rotated by an inverter (V/F control), the definition of motor start torque differs from that of when rotated by a commercial power supply and is as follows.
In the low-frequency range, the start torque refers to the maximum torque that can be generated with up to 150% larger capacity than the inverter overcurrent capacity. The term start torque in this context differs in definition from start torque used in commercial power supply related context. Accordingly, start torque with the definition introduced in this section is referred to as "maximum start torque". Refer to Fig. 2.34 to understand the maximum start torque. The figure shows that the maximum output frequency within the current limit of the inverter is 6Hz. Therefore, the maximum start torque is the maximum torque at 6Hz. In frequencies lower than 6Hz, locking the motor shaft does not cause an overcurrent trip on the inverter. Note, however, that locking for a long time may cause an overload shut-off (THM).
Good to know for checking an inverter
An inverter is provided with a function that sets the starting frequency (0 to 60Hz). The higher the starting frequency is, the larger the motor start torque and starting current are. Do not change the default start frequency unless there is a load such as a vertical lift load whose load torque is larger than the motor torque at start, causing the motor to rotate in the reverse direction. To increase the start torque, adjust the manual torque boost.
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2.6.2 Acceleration
After started up, an inverter gradually increases the output frequency to the frequency command value in accordance with the acceleration time setting value. As described in Section 1.3.3 Slip, the motor accelerates with a delay of the slip compared to the synchronous speed, which is proportional to the motor output frequency f. A value of this slip depends on values of the load inertia moment, load torque and motor generated torque. If the acceleration time is set sufficiently long, the output frequency f and motor speed N increase in proportion to each other. (Refer to Table 2.35.) Note that too short acceleration time causes a large gap between f and N, by which f and N increase with a large slip value (refer to Fig. 2.36.). This makes a motor current larger and may generate overcurrent, resulting in protective functions, such as the stall prevention function or the overcurrent shut-off function, to operate. (If an inverter capacity is increased whereas a motor capacity is not increased, the overcurrent resistance becomes relatively higher. Accordingly, the protective functions will be hard to operate.) With a general-purpose inverter, to minimize the start current, the acceleration time must be set in accordance with the load as described above.
Output frequency f N f Motor speed N t
f N f N The slip is large. t Overload resistance when the inverter capacity is increased Rated current
Overload resistance when the inverter and motor have the same capacity. Rated current
Fig. 2.35 Acceleration characteristics (with sufficient acceleration time)
Fig. 2.36 Acceleration characteristics (with insufficient acceleration time)
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Good to know for checking an inverter
Generally, if a motor is powered directly from a commercial power supply, a current that is 6 to 7 times larger than the rated current flows in the motor (refer to Section 1.4). The motor starts in the acceleration time that is defined by the load characteristics (refer to Section 1.9.1). If an inverter with the same capacity as the motor capacity is used to directly start the motor (e.g. On the inverter output side, turn MC on.) in the same manner, a trip occurs with the start current. Therefore, an inverter must start with a low frequency to start a motor. (At approximately 3 to 6Hz, the start current does not exceed 150% of the rated current.) The reason that nothing must be turned on or off on the inverter output side is that the start current is directly input and flows as described above.
2.6.3 Overcurrent stall prevention
During acceleration, if a motor current exceeds 150% (overload resistance of an inverter), the inverter stops increasing or decreases the output frequency. This is to avoid the overcurrent shut-off protective function being operated.
Acceleration completed f
Stall prevention operation Starting frequency t
Fig. 2.37 Stall prevention operation during acceleration
Good to know for checking an inverter
Measures for when the overcurrent shut-off operated during acceleration (a) When a trip occurs right after the start signal is turned on ▪ Decrease the manual torque boost. ▪ Increase the manual torque boost. Or, increase the starting frequency. ▪▪▪This measure is applied to when the motor is rotating in the reverse direction (such as when a vertical lift load is used). (b)When the motor trips and does not accelerate after its rotation is started ▪ Set a longer value to the acceleration time. ▪ Increase the manual torque boost. ▪ Modify mechanical looseness. ▪▪▪ This measure is applied to when the machine does not start even though the motor rotates. (c) When a trip occurs at 10-odd Hz or higher ▪ Set a longer value to the acceleration time. * With the FREQROL-A700 series, the inverter output frequency at a trip can be read by the monitor function of the parameter unit. The parameter unit shows the alarm contents when a trip occurred. To display the frequency, output current and output voltage at the trip, switch the display with the shift key.
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2.6.4 Constant-speed operation
When the output frequency matches the frequency command value, the acceleration ends and the motor continues to rotate at a constant speed.
Overcurrent stall prevention
During the constant-speed operation, if a motor current exceeds 150% (overload resistance of an inverter), the inverter decreases the output frequency once to prevent an overcurrent-caused trip from occurring. The inverter returns the output frequency to the original value when a motor current becomes smaller than 150%.
t Stall prevention operation f
Fig. 2.38 Stall prevention operation at a constant speed
Good to know for checking an inverter
Measures for when the overcurrent shut-off operated during the constant-speed operation (a) When the operation is performed at the base frequency or lower ▪ Increase the manual torque boost. (b) When the operation is performed at 10Hz or lower ▪ Decrease the manual torque boost. (c) Increase the inverter capacity if the load torque is temporary larger than 150% of the rated motor torque.
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2.7 Deceleration/Stop Characteristics of Inverter
2.7.1 Deceleration
When the inverter start signals (STF and STR) are turned off or when the frequency command signal is set to a value below the output frequency, an inverter decreases the output frequency in accordance with the deceleration time setting value.
Deceleration time setting value t f
N Slip (Less than 0)
Fig. 2.39 Deceleration characteristics During deceleration, the motor speed is faster than the synchronous speed, which is equivalent to the inverter output frequency. In this condition, the motor functions as a generator and returns the energy to the inverter. This is why DC voltage (voltage of the smoothing capacitor) increases. This operation is called regeneration. To stop a motor rotating with a commercial power supply, turn off the magnetic contactor used for stopping a motor. The motor coasts to stop using the load torque as a braking force. (Refer to Section 1.9.1 for stop time.) With an inverter used, the motor does not coast to stop by turning the start signal off but decelerates to stop in accordance with the deceleration time setting value. Depending on the deceleration time setting value, the motor goes into the following status. Table 2.2 Relationship between deceleration time and regeneration Deceleration time condition Motor status Motor slip Deceleration time setting value > Coasting stop time Driving (motor) 3 to 5% or less Deceleration time setting value < Coasting stop time Regeneration (generator) Less than 0 During regeneration, a motor functions as a generator, charging the smoothing capacitor on the converter part. Therefore DC voltages of this smoothing capacitor increase at its both ends (voltage between the terminals P-N). If the set deceleration time is too short, the regenerative overvoltage protection function or overcurrent (regenerative current) protection function operates. Set longer deceleration time to avoid this. If the inverter does not have a regenerative brake circuit, install the optional product FR-BU type brake unit or FR-CV/FR-RC type power regeneration converter.
Deceleration completed t f Stall prevention operation
Fig. 2.40 Stall prevention operation during deceleration ▪ Overvoltage stall prevention If the DC voltage becomes even higher, the inverter stops decreasing the output frequency. This is to avoid the regenerative overvoltage shut-off protective function being operated.
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▪ Overcurrent stall prevention During deceleration, if a motor current exceeds the specified value, the inverter stops decreasing or increases the output frequency. This is to avoid the overcurrent protective function being operated.
2.7.2 Stop
(1) When the inverter start signal (STF/STR) is turned off, the motor decelerates as shown in Fig. 2.40. When the output frequency goes down to the DC injection brake operation frequency or lower, the DC voltage is applied to the motor, and then the motor stops. This is called DC injection brake. After the DC injection brake is performed for a certain time, the base signal of a transistor is turned off, by which the output is shut off. (2) If the magnetic contactor (MC) on the inverter input side is turned off, a power failure is detected and the base circuit of the transistors is shut off. As a result, the motor coasts to stop. Therefore, when using the inverter to make the motor stop through deceleration, do not turn off the input power supply of the inverter. DC injection brake When the DC voltage is applied to a motor which is rotating, a brake torque is generated. This brake torque becomes zero when the motor stops. (The operation frequency, operation time and operation voltage can be changed.) Fig. 2.41 DC injection operation
DC injection brake f Deceleration DC injection brake operation frequency
Good to know for checking an inverter
Measures for when the overcurrent shut-off Refer to Section 3.5.7. (b) When a trip occurs right before (while the DC injection brake is in operation) the motor stops ▪Decrease the DC injection brake voltage. (c) Set a longer value to the deceleration time. operated during deceleration (a) When a motor with a brake is used and trips right after deceleration starts
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DC bus voltage
Motor current
Inverter input current
2 seconds of acceleration time setting
Fig. 2.42 Measurement example of acceleration characteristics
直流母線電圧 DC bus voltage
Motor current モータ電流
Inverter input current インバータ入力電流
2 seconds of deceleration time setting 減速時間設定2秒
Fig. 2.43 Measurement example of deceleration characteristics
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2.8 Efficiency and Power Factor of Inverter
2.8.1 Efficiency
As described in Section 2.1, an inverter is a power supply conversion unit consisting of a section that performs forward conversion (the converter part) and the other section that performs reverse conversion (the inverter part), and therefore a loss is unavoidable for such conversion sections. In spite of the loss, generally, inverters are said to improve power saving. The following describes the reason of this using the formula of an inverter input current and efficiency.
Motor Power supply PIN IINV Loss WINV Efficiency INV Inverter PM IM Loss WM Efficiency M P:Power I:Current IM POUT Load
Fig. 2.44 I/O current relation chart
Output Efficiency = Output = Input Output + Loss Inverter input power PIN = Inverter output power PM Inverter output power Inverter loss WINV = Inverter efficiency INV (Motor input power) + Motor output POUT Motor efficiency M (2.1) (2.2)
Motor input power PM = Motor output POUT + Motor loss WM =
Motor output POUT = Motor output torque
Motor speed =
Machine force Machine efficiency
From the above, the inverter input current can be calculated as follows:
Inverter input power = Motor output + Motor loss + Inverter loss = Total efficiency = Inverter efficiency
Motor output Total efficiency
(2.5) (2.6)
Motor efficiency at inverter drive
As shown in Formula (2.5), when a motor is rotating, a motor loss is larger with an inverter than with a commercial power supply due to harmonic, etc. In addition to this, there is an inverter loss if an inverter used. Therefore an inverter needs larger input power than a commercial power supply does to realize the same motor speed. However, if the motor speed is decreased by an inverter, the motor output decreases in the same manner. Accordingly, the lower the speed becomes, the less the input power is needed even if the load torque is constant. (Especially, if reduced-torque loads such as a fan or pump are the target, the input power needed decreases more greatly, realizing better energy saving.)
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2.8.2 Power factor
Normally, as shown in Fig. 2.45, a power factor can be calculated from a phase angle φ between voltage and current. For an inverter, however, a power factor cannot be defined as cosφ since the input current of an inverter is in a distorted waveform including harmonic as described in Section 2.2. (A power-factor meter indicates approximately 1 if used.) On the other hand, a power factor is equivalent to a ratio of the effective power to the apparent power. Therefore the power factor for an inverter can be calculated in Formula (2.7).
Effective power Apparent power
Inverter operation Voltage Current Commercial operation power factor = cos Voltage Current
Fig. 2.45 Input voltage/current waveform (3-phase)
Power factor =
Effective power PIN Effective power + Ineffective power Inverter output power PIN 3 Power supply voltage Inverter input current IINV (2.7)
2.8.3 Inverter input current and power factor improvement
In the waveform of inverter input current, a distortion ratio changes in accordance with the impedance (reactance of transformers or cables) on the power supply side, resulting in the change of input current (effective) value. However, as described in Section 2.8.1, the power supply voltage and inverter input power do not change as long as the motor output does not change. Therefore, Formula (2.7) is used to change a power factor. The smaller the reactance on the power supply side is, the smaller the current is (i.e. the better the power factor is). With an inverter installed near a large-capacity power supply converter, the current increases if the reactance is small, deteriorating the power factor. Therefore, to improve a power factor, make the power supply reactance larger. To do so, install a reactor on the DC circuit of the inverter (improved to approximately 93% by a power factor improving DC reactor) or on the AC input side (improved to approximately 88% by a power factor improving AC reactor). A power factor of commercial power supplies is in the range of 0.75 to 0.85, which is almost constant. This is why the formula of "current voltage" can be formed. In contrast, a power factor for inverters considerably changes from about 0.6 to 0.9 depending on the condition of the power supply reactance, and therefore the formula cannot be formed for inverters. Consequently, an inverter input current may become smaller than the motor current while the rated torque is output. For further understanding, calculate actual numerical values in Example which follows.
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1) Power factor improving AC reactor FR-HAL(H) A power factor improving AC reactor improves a form factor of the inverter input current and a power factor, reducing the power supply capacity. Also, it is effective in reducing the input side harmonic current. Improvement effect Operating environment Power supply power factor 88% (when load is 100%) ● Ambient temperature ● Ambient humidity ● Ambiance Voltage Connecting method -10 to +50 ● Vibration 5.9m/s2 or less 90%RH
No dust and dirt, corrosive gas, flammable gas 50/60Hz (380 to 480V 50/60Hz)
3-phase 200 to 240VAC
Connect to the inverter input side.
NFB Power supply FR-HAL R X S T Y Z Inverter R S T
Fig. 2.46 FR-HAL connection example 2) Power factor improving DC reactor FR-HEL(H) The DC reactor is smaller and lighter than the AC reactor and allows less loss with the same effect. Power factor improving effect Operating environment Power supply power factor 93% (when load is 100%) ● Ambient temperature ● Ambient humidity ● Vibration ● Ambiance
Power factor improving reactor FR-HEL P1 Make sure to remove the jumper across terminals P1- P. P
-10 to +50
5.9m/s or less No dust and dirt, corrosive gas, flammable gas
*The cable between the reactor and the inverter
Wiring distance Do not exceed 5m.
should be 5m or less and as short as possible. The size of the cable should be the same
NFB Power supply R S T
N P1 P (PR) U Inverter V W
Motor IM
as or larger than that of the power supply cable.
Fig. 2.47 FR-HEL connection example
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Good to know for checking an inverter
By making the input current smaller with a power factor improving reactor, the following advantages are obtained. ▪ Peripheral devices on the inverter input side can be smaller. ▪ Harmonic current can be smaller. ▪ An inverter can be protected from the surge voltage of the power supply side ▪ The peak current of the converter part at power on can be suppressed. A power factor improving AC reactor provides the power factor improvement of approximately 88% at the best, whereas a DC reactor provides 93%.
Calculate an input current, motor current and inverter input current respectively for each of the following conditions: a conveyor is operated at 30m/min with a commercial power supply, a conveyor is operated at 30m/min and 15m/min with an inverter. Given values are: the power supply is 200V60Hz, the motor efficiency cosφ = 0.88
(1) Commercial operation (30m/min) PM = POUT/ IM =
= 0.9, the motor power factor
7.5/0.9 = 8.33 [kW] = 8.33 103 3 200 0.88 = 27.3 [A]
PM 3 E cos
(2) Inverter operation (30m/min) PM = POUT/ PINV = PM/ IM =
' = 7.5/0.85 = 8.82 [kW] [kW] = 28.9 [A] 9.29 103
( (
= 0.85) 0.95)
PM 3 E cos
8.82 103 3 200 0.88 =
3 E Inverter power factor
3 200 Inverter power factor
When inverter power factor is 0.93 : IINV = 28.8(A) When inverter power factor is 0.7: IINV = 38.3(A) (3) Inverter operation (15m/min) PM = POUT/ PINV = PM/ IM = IINV =
POUT = 7.5 [kW] = 15/30 = 3.75 [kW] ( ( = 31.8 [A] 5.21 103 3 200 0.7
= 3.75/0.8 = 4.69 [kW] [kW]
= 0.8) = 0.9)
PM 3 E cos
4.69 103 3 200 0.85 =
(cos =0.85) (E=100V if V/f is constant) = 21.5 [A]
3 E Inverter power factor
DC bus voltage
Motor current (inverter output current)
Inverter input current
Fig. 2.48 Measurement example of I/O current waveform (50Hz)
Fig. 2.49 Measurement example of I/O current waveform (with a power factor improving reactor of 50Hz)
Fig. 2.50 Measurement example of I/O current waveform (20Hz)
Fig. 2.51 Measurement example of I/O current waveform (with a power factor improving reactor of 20Hz)
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This chapter describes points and measures when an inverter is selected according to the capacity, number and operation status of a motor to be driven. Since the detailed explanation on the actual capacity selection is given in technical notes, this chapter casts a general notion of capacity selection.
Points for understanding!
1. Most suitable combination of motor and inverter capacities 2. Capacity selection for driving multiple motors 3. Difference between acceleration and deceleration
3.1 Capacity Selection
When an inverter is considered to be the power supply of a motor, the larger capacity inverters are better. The larger capacity inverters can directly start (turn on/off on the inverter output side) motors as if a commercial power supply is used. However, it is not preferable to increase the needless capacity when the economic efficiency and dimensions are taken into account. To make a selection for the most suitable capacity which allows the trouble-free operation, clearly understand the following sections.
3.1.1 Capability of inverter
The capability (not function) to drive a motor can be known by understanding the flow of an energy changed according to operation status. (1) During acceleration or constant-speed operations The capability is a peak current which indicates the largest current an inverter can offer when a motor requests. This amount is expressed as a rated output current or an overload current rating. (2) During deceleration During deceleration, a motor acts as a generator and the energy flows back into the inverter side contrary to acceleration and constant-speed operations. The capability for disposing of (consuming) this energy is the inverter's capability during deceleration. The motor consumes part of the energy regenerated from the load side. The
Energy (regeneration)
Energy (driving)
remaining energy deducted by the consumed energy is that to be disposed of by the inverter. To be specific, the inverter suppresses the smoothing capacitor terminal voltage increased by the regenerative energy under the specified value, by consuming the energy or returning it to the power supply side.
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3.1.2 Points for capacity selection
The inverter capacity must be selected by not only compatibility with a driven motor but also load characteristics and operation methods/statuses. (1) Motor capacity Note that when V/F control is used with an inverter drive, the motor output torque in the low-frequency range is smaller than that when V/F control is used with the commercial power supply. Otherwise, unexpected troubles occur such as disability of the inverter start-up. The same can be said for motor temperature rise. (Refer to Section 1.5 and 1.6.) (2) Operation method When selecting the inverter capacity by the capacity or number of driven motors, first select the one so that a total of the motor current does not exceed the rated inverter current. To drive multiple motors with one inverter is a feature of the inverter drive. However, the inverter capacity may become extremely large depending on the operation method, which is not economically efficient. In addition, this kind of drive easily causes capacity selection errors. The V/F control must be selected to drive multiple motors with one inverter since the advanced magnetic flux vector control, etc. are not available for it. The following lists the general operation methods: 1) One motor is driven with one inverter. 2) Multiple motors are driven with one inverter. 3) Multiple motors are driven by switching with one inverter. 4) Motor output shaft is turned on/off with a clutch. 1) When one motor is driven
Rated output current of inverter Indicated in the specifications column of a catalog.
rated current of motor Value of motor rating plate
Increases by distorted waveform
(a) Selecting an inverter corresponding to a motor using the motor capacity "kW" is not a proper method. Select an inverter so that the condition of formula (3.1) can be satisfied in reference to the rated motor current. The reason is that when the number of poles increases, the rated current value becomes large for reduced motor efficiency and power factor even if the motor capacities (kW) are not changed. For the standard motors (2, 4, 6P), selecting an inverter according to "kW" does not cause a specific problem. (b) The motor with a capacity larger than the inverter is not available.
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2) When operating multiple motors in parallel with one inverter Rated output current of inverter total of rated motor current
I1 Inverter I2
When multiple motors are operated in parallel, the motors cannot be protected by the built-in electronic thermal relay function. Provide a thermal relay for each motor on the inverter output side. For a continuous drive at low-speed, however, install a temperature detection device on the motors since the motors cannot be protected by the thermal relay function.
(3) Operation pattern When the acceleration or deceleration time is restricted, the selection of inverter capacity cannot be fully made only by matching the inverter capacity with the motor capacity (selecting with a current). The capacity must be selected so that the predetermined acceleration/deceleration time can be satisfied. The inverter capacity may increase for the operation which repeats acceleration/ deceleration in a short time or for the vertical lift operation. Make sure to fully consider the inverter capacity in advance. [Example] 1) When rapid acceleration/deceleration or cycle operation is performed (machine tool, cart, etc.) 2) When the vertical lift operation is performed
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Can the inverter with one rank higher inverter capacity used?
■ When the inverter capacity is increased, the motor torque (force) becomes larger.
The motor generated torque when an inverter is used is less than that when the commercial power supply is used. Depending on the size of the load, the current increases for insufficient torque (force), and the protection function may be activated. To solve insufficient torque, one of the two methods can generally be taken: increasing the motor capacity (the inverter capacity must also be increased) or increasing only the inverter capacity with the motor capacity left unchanged. Since the former method costs more and makes motor dimensions larger the latter, the latter is frequently taken. The increased inverter capacity allows the larger inverter output current, which increases the motor generated torque.
■ The rise of the motor temperature cannot be improved even if the inverter capacity is increased.
When the rise of the motor temperature occurs during a continuous operation at low-speed, it cannot be improved even if the inverter capacity is increased. Since a motor is cooled off with its cooling fan, the cooling capability cannot improved by increasing the inverter capacity. When the inverter capacity is increased, a measure against the motor overheat must be considered since the motor is forced to operate. In this case, it is important to properly set the inverter electronic thermal according to the motor capacity.
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3.2 Selection with Operation Pattern
The basic operation pattern of a motor is start → acceleration → constant speed → deceleration → stop. Each process has points for selection which are overviewed in the following.
2 Is acceleration possible? The magnitude of a motor torque must be larger than that of the torque required for acceleration (Ta TL).
4 Check the motor temperature. The risen temperature must be within the specified value. 1 Is deceleration possible? The brake torque required for deceleration must be assured. The capability for energy consumption or power regeneration must be assured.
1 Is start possible? The motor start torque must be larger than the load start torque.
Time ta(s) Acceleration time Load torque TL td(s) Deceleration time
Acceleration Ta torque Td Deceleration torque
J N 9.55 ta Td J N 9.55 td
Required motor torque Ta TL
Ta TL Required brake torque Td TL
The key is the magnitude of the motor output torque. The torque varies depending on the motor capacity, inverter capacity, control system and boost amount.
The key is the inverters regeneration capability. The regeneration capability varies depending on the selections of the inverter capacity, brake unit model, power regeneration converter.
Fig. 3.1 Operation pattern and torque
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3.2.1 Start
The motor starts at the intersection of the motor generated torque with the load torque (point A in Fig 3.2). Since the motor is locked while the inverter output frequency is between 0 and point A, the intersection point must be below the maximum start frequency to prevent the inverter from tripping due to the locked rotor current. (Refer to Section 2.6.1.)
For advanced magnetic flux vector control Maximum motor torque (Changes depending on the boost amount)
Point A
Load torqueTL
fa' The motor starts at this frequency.
Output frequency
Fig. 3.2 Start of motor
3.2.2 Acceleration
The magnitude of motor output torque must be more than that required for the acceleration (Ta + TL). There are two acceleration types: a non-linear acceleration which is performed with the operation of the stall prevention (current limit) function and a linear acceleration which is smoothly performed without the operation of the stall prevention (current limit) function. The non-linear acceleration is considered for the general use. Consider the linear acceleration for the fixed position stop operation with an elevator, etc.
Good to know for checking an inverter
To increase the acceleration capability and the start torque
Select the advanced magnetic flux vector control (FREQROL-A500, A700 series), the real sensorless vector control (FREQROL-A700 series) or the general-purpose magnetic flux vector control (FR-E500, A024 series).
• Increase the torque boost adjustment amount. • Increase the inverter capacity. • Increase the motor and inverter capacities.
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3.2.3 Deceleration
The magnitude of the regenerative brake torque is determined according to the motor and inverter loss. That is to say, the deceleration capability is determined by the inverter loss for an inverter with a built-in brake and by the motor loss for an inverter without a built-in brake. Increasing the capacity for an inverter with a built-in brake is effective to increase the regenerative brake torque. However, doing it for an inverter without a built-in brake is not. Use the BU type brake unit. While the magnitude of the brake torque has been satisfied, it is necessary to consider the brake resistor's capacity not to overheat during deceleration. The energy regenerated to the inverter at deceleration (WINV) must be fully consumed within the capability of the brake resistor. When a larger brake capability is required, use a power regeneration common converter (FR-CV) which generates the braking power by returning the regenerative energy (WRC) to the power supply.
Without power regeneration converter With power regeneration common converter During acceleration Motor Inverter IM Load
During acceleration NFB Power supply
Power supply Power regeneration common converter Inverter IM WM Load
WM Brake resistor
Total energy at regeneration WMECH W RC
Total energy at regeneration W MECH
Fig. 3.3 Flow of energy at deceleration
Good to know for checking an inverter
To increase the regenerative brake torque
• Increase the inverter capacity.
This method is effective when the regenerative brake circuit is built in an inverter; however, not effective when it is not.
• Use the power regeneration common converter (optional). • Use the BU type brake unit (optional). • When the BU type brake unit has already been used, use the one with a larger capacity or the
power regeneration common converter. However, when the capacity of the BU type brake unit is larger than that of the inverter to be combined, the inverter capacity must be increased.
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Regenerative brake function
The inverter brakes the motor speed by consuming the regenerated energy. This consuming circuit is a regenerative brake circuit. The operation is explained taking a built-in type regenerative brake circuit in Fig. 3.4 as an example. The voltage E of the smoothing capacitor C increases with the regenerative energy. When the voltage exceeds the specified value, the transistor on the regenerative brake circuit TRd conducts, and the current Id flows to the regenerative brake resistor R. The regenerative brake resistor generates heat with this current, and the regenerative energy is consumed. The energy charged in the capacitor decreases with this operation, and the voltage E drops. When the voltage E drops below the specified value, the transistor on the regenerative brake circuit TRd stops conducting, and the current of the regenerative circuit is shut off. These operations are repeated during deceleration. However, the duty of the regenerative brake circuit decreases or the circuit may not operate when the regenerative energy is small (the torque required for deceleration is small). The duty of the regenerative brake circuit is set to 2 to 3% according to the heat generation of the circuit. Therefore, the regenerative brake resistor overheats or a fault occurs in the transistor when the duty is needlessly changed. An optional BU type brake unit is an equivalent of a built-in brake circuit installed outside. Fig 3.4 Brake circuit
N- E C R TRd Id W P+ U Brake circuit
To motor
Good to know for checking an inverter
The necessity of the BU type brake unit is defined as follows. When the DC voltage between P+ and N- is measured with a tester, and if the voltage right after deceleration start increases close to the stall prevention operation voltage shown in Section 2.5.3, the brake unit is required. Besides, when the voltage more than the brake operation voltage is maintained, even if the brake unit is built in an inverter, increase the brake unit capacity in case of insufficient brake capability.
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● Heat capacity of regenerative brake (temperature rise)
The capability of the regenerative brake unit is determined by the regenerative brake torque described in the previous section and the power consumption. The regenerative brake torque is subject to the regenerative current value flowing in the brake resistor, which is determined by a resistance value (Ω) of the resistor. When the regenerative current flows for a long time, the heat generation exceeds the permissible value of the resistor. This permissible value is the rated power of the resistor (W). For the high-frequency operation pattern or the continuous regeneration load (an elevator, etc.), consideration of the heat capacity for the regenerative brake is required.
● Power regeneration common converter (FR-CV)
This converter has a compact body and following characteristics. 1) Enhances the braking capability. 100% torque continuous regeneration and maximum 150% torque and 60 second regeneration are enabled. 2) Reasonable common converter system Using the regenerative energy for other inverters and returning the remaining energy to the power supply lead to the energy savings.
Regenerative energy Power regeneration common converter Inverter Driving Inverter
The remains of the regenerative energy return to the power supply side as shown in dotted lines. 3) Easy enclosure design Adopting a compact body allows an easy in-panel design. Installing a heat sink outside the panel suppresses the rise of in-panel temperature and downsizes the panel.
Good to know for checking an inverter
An elevator generally spends longer time for the regenerative operation. Therefore, the time for one cycle and the load torque at the minus torque for the lifting height (m) (especially machine efficiency) are important factors for capacity selection.
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3.2.4 Rise of motor temperature
(1) The motor temperature rise for the continuous operation is different from that for the cycle time operation. This fact requires the consideration of motor heat according to operation methods. Continuous operation Operation frequency Consideration of motor heat
Cycle time operation
10 times or more operations per hour
10 times or less operations per hour
Forward rotation
Time Reverse rotation
Motor speed
For the magnetic flux vector control (0.4 to 1.5kW) Torque must be within this continuous permissible torque range. 100 50
120 Hz
• Consider the torque value of the output characteristics for the running speed.
Obtain the motor equivalent current value from the current for each running interval and the cooling coefficient. The result must be below the rated motor current. The temperature rise of the inverter operation is generally smaller than that of the commercial power supply operation due to the restrictions of the inverter overload current rating.
Fig. 3.5 Operation pattern and motor temperature rise (2) Heat-resistant class of motor The heat-resistant class indicates the type of insulating materials used for the motor and indirectly expresses the permissible value of motor temperature rise. Among the standard motors, small capacity motors adopt the insulation type E or B and motors with intermediate capacity or more adopt F. When the ambient temperature is high or when the torque is increased without changing the motor size, a special motor with the upper heat-resistant class is used. Table 3.1 Heat-resistant class of motor Heat-resistant class E B F Maximum permissible temperature [ ] 120 125 155 Coil temperature rise limit [K] (Resistance method) 75 80 105
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3.3 Effect of Machine Reduction Ratio
For small capacity motors (7.5kW 4P or less), up to 120Hz are available when the standard motor is used. The reduction ratio on the machine side up to 50Hz has conventionally been determined with reference to the machine speed of 60Hz as a maximum ratio. However, by increasing the reduction ratio to enhance the inverter output frequency (60Hz to maximum 120Hz), the load torque and load inertia moment of the motor shaft are reduced, and therefore the following advantages are developed. (1) Starts become easier as the reduction ratio increases. (2) Continuous use is enabled at low-speed. (The standard motor will do on the occasion when the inverter dedicated constant torque motor should be selected.) (3) A motor can be used in the wide speed deviation range. Relationship between the reduction ratio i and the motor shaft-equivalent load torque TL and load inertia moment TL=TLL×i JL=JLL×i
Reduction ratio i
TLL: Load torque for load shaft JLL: Load inertia moment for load shaft
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3.4 Capacity Selection Procedure
Motor shaft-equivalent Frequency load torque Acceleration torque Motor speed
Conditions on the machine side
f1 f2
Mechanical brake operation Inverter output stop
TLS TLmax TLmin Ta
Deceleration torque
Td Ta TLmax
Items for consideration
Required motor torque
Motor current
(Td TLmax)
l2 l4
l3 c2 c3 c1 c4 c5
Cooling coefficient c
t1( ta)
t2 tc(1 cycle)
Fig. 3.6 Typical speed patterns and items for consideration
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Stop accuracy
Table 3.2 List of data symbol and unit Data Symbol Required power PL Motor capacity PM Number of motor poles P Motor speed N Frequency f Travel speed V Load mass W Machine efficiency η Friction coefficient μ Motor shaft-equivalent load torque TL Motor shaft-equivalent start load torque TLS Motor shaft-equivalent load inertia moment JL Inertia moment of motor shaft-equivalent JB mechanical brake Cycle time (1 cycle) tc Time for each running interval tn Acceleration time ta Deceleration time td Minimum acceleration time tas Minimum deceleration time tds Acceleration Acc Rated motor speed NM Rated motor torque TM Maximum motor start torque TMS Acceleration torque Ta Deceleration torque Td Load torque ratio TF Motor inertia moment JM Maximum torque coefficient for short time αm Continuous operation torque coefficient αc Maximum start torque coefficient αs Acceleration torque coefficient αa Brake torque coefficient (Generic name) β Hot coefficient δ Cooling coefficient C Motor current I Motor equivalent current value IMC Regenerative power absorbed by a motor WM Average power regenerated to the inverter WINV Average power regenerated from a machine WMECH Continuous permissible power of braking unit WRC Permissible power for short time per running of the WRS braking unit Stop time tb Coasting distance S Stop accuracy Δε
Machine side data
Unit kW kW ― r/min Hz m/min kg ― ― Nm Nm kg kg s s s s s s m/s2 r/min Nm Nm Nm Nm % kg ― ― ― ― ― ― ― % % W W W W W s
Regenerative power
Data used for consideration
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3.4.1 Consideration procedure for continuous operation
1. Selection flowchart
Required power calculation
① Selection outline ● Calculate the required power for consideration. ● Tentatively select the motor capacity to be used according to the size of the required power. ● Tentatively select the inverter capacity compatible with the tentatively selected motor capacity. Judgment (Required power PL) (Load torque TL) Motor capacity PM Required power PL Rated motor torque TM Load torque TL
Motor capacity tentative selection
Inverter capacity PINV Motor capacity PM (Rated inverter output current > Rated motor current)
Inverter capacity tentative selection
● Consider the start
④ availability since the motor must start rotation from stop for the operation. Motor start torque TMS > Load torque at start TLS
Start availability
● Consider whether the
⑤ magnitude of load is within the permissible temperature of the motor. Motor continuous operation torque TMC inequalityLEM Load torque TL
YES NO Continuous operation availability YES NO Consideration of minimum acceleration time YES
● Calculate the minimum
value of the acceleration time. Consider whether the planned acceleration time is satisfied.
Minimum acceleration time tas < Planned acceleration time ta Minimum acceleration time tas 45 seconds
Consideration of options for brake
● Calculate the minimum ●
value of the deceleration time. Consider whether the planned deceleration time is satisfied. Minimum deceleration time tds < Planned deceleration time td
Consideration of minimum deceleration time YES
● Calculate the torque
required for deceleration from the deceleration time during operation. Consider the processing capacity of the regenerative power during deceleration. Consider the processing capacity of the regenerative power during the continuous regenerative operation. Deceleration torque Td
Consideration of regenerative power YES
Permissible power for short time WRS > Regenerative power during deceleration WINV
Continuous permissible power WRC > Regenerative power during the continuous operation WINV
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Calculation formula, etc. ① ● Load torque TL TL=9550×PL/N [N・m]
Reference material/item ● Technical Note No.30 (Refer to the appendix.)
Remarks (precautions, etc.) ● Note the insufficient torque since the motor output torque is reduced for the operation at 60Hz or more. ● The permissible motor speed (operating frequency range) differs according to the motor capacity, pole numbers and model.
● Rated motor torque TM TM=9550×PM/NM [N・m] ②
● Motor catalog/Instruction manual ● Technical Note No.30 Refer to [Table of characteristics] in Chapter 4 Motor/Brake Characteristics. ● Inverter catalog (Standard specifications)
● The motor generated torque differs according to the inverter type or the control. (Magnetic flux vector control < V/F control) ● A built-in brake circuit is present/absent according to the inverter type. ● The start torque of the magnetic flux vector control is larger than that of the V/F control. ● The start torque can be improved if only the inverter capacity is increased.
● Motor start torque = Maximum start torque s Maximum start torque TMS = TM α > TLS
Continuous operation torque coefficient α c >L Load torque ratio TF=TL/TM or c> Continuous operation torque TM α Load torque TL ● Minimum acceleration time tas
JL JM N a TLmax TM
N m
● Technical Note No.30 Refer to [Data for each torque type] in Chapter 2 Driving Capability Data. α Maximum start torque s: coefficient δ: Hot coefficient ● Technical Note No.30 Refer to [Continuous torque] in Chapter 2 Driving Capability Data. α Continuous operation c: torque coefficient ● Technical Note No.30 Refer to [Torque type] in Chapter 2 Driving Capability Data. α Acceleration torque a: coefficient ● Technical Note No.30 Refer to [Braking capability torque types] in Chapter 3 Driving Capability Data. β: Deceleration torque coefficient ● Technical Note No.30 Refer to [Braking capability torque types] in Chapter 3 Driving Capability Data. WRS: Permissible power for short time WRC: Continuous permissible power
● For the magnetic flux vector control, the continuous operation torque range becomes larger according to the motor capacity.
● Minimum deceleration time tds
JL JM N TM TLmin
N m
● Deceleration torque Td ● Regenerative power from a load WMECH ● Power absorbed by the motor WM ⑧ ● Regenerative power to the inverter WINV = WMECH - WM [W]
● The acceleration torque of the magnetic flux vector control is larger than that of the V/F control. ● Recalculate with the linear acceleration torque coefficient when the minimum acceleration time exceeds 45 seconds. ● The value of the minimum deceleration time differs according to the presence/absence of a built-in brake resistor. ● Consider using options for the brake when the minimum deceleration time is larger than that planned. ● The capacity of regenerative power (permissible power) differs according to the inverter type and capacity. ● The power regeneration converter may be required for continuous regeneration.
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3.4.2 Consideration procedure for cycle operation
2. Selection flowchart
Selection outline
Power calculation
Tentatively capacity PM > P L selected motor
Motor capacity tentative selection Inverter capacity tentative selection Start availability Low-speed operation availability NO Start is available. YES Acceleration torque calculation (Acceleration availability) NO Acceleration is available. YES Brake unit tentative selection (Simplified selection is also available.) Deceleration torque calculation (Deceleration availability) NO Deceleration is available. YES Consideration of regenerative power NO Thermal use of the brake system is available. YES Determination of brake system
Also calculate the load torque and inertia moment. (1) Select the motor capacity larger than the required power. (1) Select the inverter equivalent to the motor capacity. (2) Increase the inverter capacity for the acceleration torque increase as necessary. ● Check that the motor start torque and the torque at low speed are larger than the load torque. δ: Motor hot coefficient ● Calculate the relationship between the acceleration speed and the acceleration time ● Acceleration torque
Tentatively selected inverter capacity PM
TMS>TLS TM×αm×δ>TLS
J Nmax 9.55 ta
N m
Ta TLmax TM
● Calculate the torque required for acceleration α Linear acceleration torque coefficient a: ● Deceleration torque
J Nmax 9.55 td
N m
min Td TLmin TM
● Calculate the torque required for deceleration. βmin: Brake torque coefficient (1) Check the permissible power for short time. (2) Check the average regenerative power. WINV: Power regenerated to the inverter td: Deceleration time during 1 cycle tc: Entire time of 1 cycle WINV<WRS WINV×td/tc<WRC
Consideration of motor heat
Motor, Inverter Brake unit Stop accuracy Check that the equivalent current value does not exceed 100%. End
(In2 tn) (Cn tn)
● Calculate the stop accuracy of the mechanical brake.
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3.4.3 Consideration procedure for vertical lift operation
3. Selection flowchart
Consideration and arrangement of the machine side data Load power calculation Motor capacity tentative selection
Selection outline
Required power PL
Inverter capacity tentative selection Start availability Low-speed operation availability High-speed operation availability NO Start is available. YES Acceleration torque calculation (Acceleration availability) NO Acceleration is available. YES
(1) Select the motor capacity larger than the required power. (2) Increase the motor capacity for the start torque increase. (1) Select the inverter equivalent to the motor capacity. (2) Increase the inverter capacity for the acceleration torque increase. (1) Motor start torque TMS > Load torque at start TLS (2) Motor torque at low speed TM αm δ > Load torque TL (3) Motor torque at high speed α m > Load torque TL TM Acceleration torque
J Nmax 9.55 ta
N m
Deceleration torque calculation (Deceleration availability) Brake unit tentative selection NO Deceleration is available. YES Consideration of regenerative power NO Thermal use of the brake unit is available. YES Determination of brake system
Ta: Acceleration torque ta: Acceleration time [s] Consider the availability of acceleration.
Tamax TM
αa: Acceleration torque coefficient
Deceleration torque
N td
N m
Td: Deceleration torque td: Deceleration time [s]
Tdmax TM
Consideration of motor heat Motor, Inverter Control unit End
β min: Brake torque coefficient (Tentatively select the brake unit according to Data volume of the technical note.) (1) Check the permissible power for short time. WINV <WRS (2) Check the continuous permissible power. WINV ×t/tc<WRC WINV: Power regenerated to the inverter t : Time taken for the minus load torque [s] tc: Entire time of 1 cycle [s] Motor equivalent current value
(In2 tn) (Cn tn)
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An elevator is different from other applications in that there are two modes when the load torque is positive (generally at rise) and negative (minus) (generally at fall) and that the cycle time operation is performed necessarily with the fixed position stop. The following lists the cases when the general-purpose inverter is used for such application. (1) Vertical lift operation ● Control method For the following reasons, it is preferable to select any of the advanced magnetic flux vector control, real sensorless vector control, general-purpose magnetic flux vector control or vector control. However, the V/F control may have an advantage in the regenerative torque at low speed. ● An elevator is always accompanied by the overload operation. Therefore, the start torque of 150% or more is required. ● For an elevator with counterweight, the negative load may be generated even at rise according to the load magnitude. The output voltage must be optimally controlled to avoid the overcurrent.
Electromagnetic brake Motor MC NFB Inverter Lifter case WLs Counter weight Wc
Reduction gear
Load WL Brake unit
Rise and fall
Fig. 3.7 Configuration example of elevator with counterweight
● Mechanical brake opening timing ● Open : For avoiding a drop of the load, open the mechanical brake after the RUN (running) signal of the inverter is turned on with the start signal. ● Close: For avoiding abrasion of the brake lining and overcurrent, fully decelerate, close the mechanical brake and turn on the inverter MRS (output stop) signal. ● Fall operation The rotation by a load causes the regenerative operation in many cases. Since the inverter cannot independently absorb the regenerative energy, a braking unit (power regeneration converter, brake unit, etc.) is required. ● Motor selection If the continuous operation is not performed at low speed, the constant torque motor is not required.
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(2) Regenerative operation
P AC reactor Power supply N This part returns the regenerative energy to the power supply. Example FR-RC IM Flow of energy during regeneration
Fig. 3.8 Regenerative operation
When the motor is rotated by an external force (e.g. gravity) such as the fall operation of an elevator, the energy generated by the motor as a generator is stored in the smoothing capacitor, and the voltage of both capacitor ends (between terminals P and N) increases. This status is called a regenerative operation. When this regenerative energy is absorbed by following systems, the braking power is generated in the motor. Resistance consumption system Power regeneration system : This system consumes the regenerative energy with heat. Since the initial cost is low, it is suitable for a small capacity inverter. : This system returns the regenerative energy to the power supply. Since large braking power can be expected with an energy saving effect, it is suitable for a large capacity inverter.
It should be fully noted that when the braking unit capacity is insufficient, the voltage of both capacitor ends (between terminals P and N) increases and the inverter falls into OVT (regenerative overvoltage) trip. Setting Pr.19 (Base frequency voltage) in the inverter according to the power supply voltage prevents the frequent occurrence of the OCT (overcurrent) alarm during regeneration. (3) Low-speed operation ● Low-speed torque The inverter drive easily causes the insufficient low-speed torque. Some measure must be taken by adopting the control system (advanced magnetic flux vector control, real sensorless vector control, etc.) according to the specifications of the machine, setting the torque boost properly, etc. ● Motor temperature rise When the continuous operation is performed at low speed, the motor temperature rise becomes large. Fully consider using a constant torque motor or reviewing the operation pattern. The appropriate boost setting is also effective to control the temperature rise during low-speed operation.
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● Stable operation High torque at start or at low speed does not exactly mean that smooth operations can be performed at low speed. To know how slowly smooth operations can be performed, the speed control range is used. For applications to be operated smoothly at ultra low speed, the vector control (speed control range 1:1500) is the most suitable. <<Example>> The speed control range 1:200 (real sensorless vector control) means that if the maximum speed is performed at 60Hz, 1/200 of the frequency, i.e. up to 0.3Hz, is the applicable range for a smooth operation.
Good to know for checking an inverter
The encoder speed feed back operation of FREQROL-A500 series, etc. is highly effective for slow load fluctuation. However, it should be noted that the operation may be sometimes unstable due to the control response delay against the uneven rotation by torque ripples at low speed and does not achieve a full improvement. (4) Inverter and mechanical safety brake An elevator must be equipped with the mechanical safety brake for holding products for rise and fall. This safety brake is also used for the positioning stop of vertical lifting. An interlock circuit must be installed to prevent the conflict with the deceleration torque from the inverter regenerative brake. (5) Selecting a fast response inverter For the elevator's acceleration/deceleration time, a fast response speed such as one to two seconds to reach high speed is required. Among the Mitsubishi general-purpose inverters, the FREQROL-A700 series with the real sensorless vector control is the most appropriate for this purpose. (6) Configurating a fail-safe system for safety The lifter may naturally drop when the motor torque is lost for the inverter protective circuit activation, power failure, power-off or motor stop. Configure a fail-safe sequence ladder in consideration of this risk. It is also recommended to install the overspeed relay on the machine side in case a motor should stall. (7) Measures against vibration/impact and cable disconnection When an inverter is installed to a moving machine such as a crane, measures must be fully taken against vibration, impact and the overrun by power cable disconnection.
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Actual selection example for continuous operation (selection example for conveyor operation)
(Load/Operation specifications) Power supply voltage/frequency 220 [V] 60 [Hz] Friction coefficient 0.1 (Friction coefficient at start 0.15 Machine efficiency 0.85 Mass of products conveyed (including a conveyor movable part) W (WT) 1800 [kg] (WL=0) Conveyor speed Vmin [m/min] 8.3 to Vmax 25 Nmin Motor speed 600 to Nmax 1800 [r/min] V fmin DR Output frequency 20 to fmax 60 [Hz] Approx. JL(J0) 0.01 [kg m2] (JG, JR=0) Load inertia moment 0.2m Total of output shaft conversion W Conveyor Planned acceleration/deceleration time Acceleration timeta 8 [s] Without a coupling, with an Deceleration timeta 8 [s] external reduction gear Reduction ratio 1/n:1/45
60Hz 20Hz
Motor SF-J R4P Without brake
Inverter FR-S500 V/F control, Margin coefficient kp=1
Operation pattern Calculation of load power and load torque (1) Required power PLR Required power PLR W Vmax 6120 0.1 1800 25 6120 0.85 9550 PLR Nmax 0.87 [kW]
(2) Motor shaft-equivalent torque TLR Motor shaft-equivalent load torque TLR 9550 0.87 1800 4.62
Tentative selection of motor capacity and inverter capacity (1) Motor capacity tentative selection Select a motor of 1.5kW for the required power of 0.87kW. Rated motor torque TM 9550 1.5 9550 PM 1800 NM Judment of motor capacity tentative selection Judgment TM 7.96 [N m] TLR 4.62 [N m] 7.96 SF-JR 1.5kW 4P
Judgment condition Rated motor torque TM Load torque TLR OK
(2) Inverter capacity tentative selection Tentatively select an inverter of the same capacity as the motor. FR-S520E-1.5K V/F control (Torque boost large)
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Consideration of start availability (1) Motor start torque Motor start torque TMS Start torque coefficient Hot coefficient TM s 7.96 1.15 0.85 7.78 [N m]
s : 1.15 Technical Note No. 30 (Driving capability data) : 0.85 Technical Note No. 30 (How to use data) s 9.8 W Vmax 2 Nmax 0.15 9.8 1800 25 2 1800 0.85 6.88 [N m]
Load torque at start TLS (2) Judgment of start availability Judgment condition
Maximum motor start torque TMS 7.78 [N m] TLS 6.88
[N m]
Load torque at start TLS OK
Consideration of continuous operation availability (1) Continuous operation torque Consider whether or not the load torque TLR fits in the continuous operation torque in the range of continuous operation (600 to 1800r/min). Motor continuous operation torque at 1800r/min (60Hz) Motor continuous operation torque TMC Continuous operation torque coefficient TM
[N m]
c :1.0(at 60Hz)
Technical Note No.30(Driving capability data) 7.96 0.8 6.36
[N m]
Motor continuous operation torque at 600r/min (20Hz) Motor continuous operation torque TMC TM
Continuous operation torque coefficient c : 0.8 (at 20Hz)
Technical Note No.30(Driving capability data)
Continuous operation torque characteristic [Technical Note No.30 (Chapter 2 Driving Capability Data)]
[N m]
Continuous operation torque
Loadtorque ratio TF
TLR TM 4. 62 ( Load torque TLR 4. 62 [N m] ) Output frequency
7. 96
0. 58
Operation range
(2) Judgment of continuous operation availability Judgment condition Judgment Maximum motor start torque TMC TMC 6.36
[N m]
Load torque TLR 4.62 OK
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Consideration of acceleration availability (1) Minimum acceleration time tas Minimum acceleration time tas Linear acceleration torque coefficient Motor inertia JM Maximum load torque TLRmax (JL JM JB) 9.55(TM a
a : 0.2
Nmax TLRmax)
(0.01 0.0068 0) 1800 9.55(7.96 1.15 4.62)
0.7 [s]
Technical Note No.30 (Driving capability data) : 0.0068[kg m2] Technical Note No.30 (Motor/Brake characteristics) : 4.62[N m] TLR is used.
(2) Judgment of acceleration availability Judgment condition Judgment tas Minimum acceleration time tas 0.7 [s] ta 8 [s] Planned acceleration time ta OK
Consideration of deceleration availability (1) Minimum deceleration time tds Minimum deceleration time tds (JL JM JB) Nmax a 9.55(TM TLRmin) (0.01 0.0068 0) 1800 9.55(7.96 0.2 0) 2.0 [s]
Linear acceleration torque coefficient Motor inertia JM Minimum load torque TLRmin
Technical Note No.30 (Driving capability data) : 0.2 2 : 0.0068[kg m ] Technical Note No.30 (Motor/Brake characteristics) : TLRmin = 0 [N m], the most difficult condition at deceleration, is used.
(2) Judgment of deceleration availability Judgment condition Minimum deceleration time tas Judgment tds 2.0 [s] td 8 [s]
Planned deceleration time ta OK
Regenerative power (when the deceleration time is 8 seconds) (1) Judgment of regenerative power processing capacity The regenerative power processing capacity is satisfied since the minimum deceleration time of 2s is shorter than the planned deceleration time of 8s in the capacitor regenerative system. <Selection result> Motor : SF-JR 1.5kW 4P : FR-S520E-1.5K V/F control (Torque boost large) Inverter Brake resistor : Not required (capacitor regeneration)
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Mitsubishi General-Purpose Inverter
Item FREQROL-S500 Small size, low price, standard functions 3φ200/400V 1φ100/200V 0.1 to 3.7kW
Selected from V/F control or automatic torque boost
Model Selection Quick Reference Table
Inverter model FREQROL-A500 FREQROL-A700 FREQROL-F700 For fan/pump, low noise 3φ200V 3φ400V 0.75 to 560kW
Selected from V/F control or optimum excitation control
FREQROL-V500 High accuracy, advanced functions 3φ200V 3φ400V 1.5 to 55kW
Vector control
Inverter type Power supply specifications Capacity
Small size, High performance, High performance, moderate functions advanced functions advanced functions 3φ200/400V 1φ100/200V 0.1 to 7.5kW
Selected from V/F control or general-purpose magnetic flux vector control
3φ200V 3φ400V 0.4 to 55kW
Selected from V/F control or advanced magnetic flux vector control
3φ200V 3φ400V 0.4 to 500kW
Selected from V/F control, real sensorless vector control or advanced magnetic flux vector control
Control method
Low noise Reset/output stop Multi-speed Brake resistor Built-in Option 15 speeds FR-S520E 0.4K or more 0 to 5VDC, 10V Speed command 4 to 20mA Alarm output Output signal Automatic restart after instantaneous power failure Low-speed torque Stall prevention Fast-response current limit 0.75kW installation area ratio % 0.75kW standard price ratio % EMC Directive Low Voltage Directive 31 55 (Dedicated noise filter available) 31 61 (Dedicated noise filter available) 100 100 (Dedicated noise filter available) 100 100 (Noise filter built-in) 100 95 (Noise filter built-in) (Dedicated noise filter available) 5Hz 150% 1Hz 150% 3Hz 200% 0.5Hz 150% 0.3Hz 200% (3.7K or less) 3Hz 120% 0r/min 100% Continuous (V/F control) 1 contact 1 type 4 to 20mA 1 contact 2 types 15 speeds 0.4K or more 15 speeds 7.5K or less 7.5K or less 15 speeds 7.5K or less 22K or less 15 speeds Output stop is optional. 15 speeds 5.5K or less 15K or less
Brake unit connection 0 to 5, 10VDC 0 to 5, 10VDC ±5V,±10V 4 to 20mA 1 contact 5 types 0 to 5, 10VDC ±5V,±10V 4 to 20mA 1 contact 5 types 2 0 to 5, 10VDC ±5V,±10V 4 to 20mA 1 contact 5 types 2 0 to 5, 10VDC ±10V 1 contact 3 types
EC Directive
UL standards cUL standards
Small size and standard. When a certain level of functions such as the multi-speed operation or motor operation with brake is required. Conveyance machine Pulley Starter General industrial machine Variable speed Conveyance machine Pulley Starter Conveyor driving When the high start torque or trip-less is required. When operation conditions are not defined. Compatible with most applications. Conveyance machine Machine tool General industrial machine Elevator When the high start torque or trip-less is required. When operation conditions are not defined. Compatible with most applications. Conveyance machine Machine tool General industrial machine Elevator Air conditioning Elevator Winding machine Conveyance machine When low noise is required for fan or pump use When the high torque, high accuracy and fast response are required.
Point for selection
Major applications
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3.5 Operation Method
3.5.1 Types of operation methods
A main characteristic of the inverter is the operation with various signals. Operation methods of an inverter (start, stop and variable speed) are roughly classified as follows. The explanation is given using the inverter FREQROL-A700 series as an example.
Operation with external signals
Start and stop signals (STF, STR)
+ Frequency setting signals Frequency setting potentiometer (volume) External signals 0 to 5, 0 to 10VDC Analog signals 4 to 20mADC Digital signals (BCD, binary) Contact signals (Multi-speed setting) Operated in combination with a computer Operated in combination with a PLC
Computer link Operation with a parameter unit (option)
Operated only by key operation of a parameter unit (FR-PU07). Inverter
Power supply
STF(STR) SD RS485 terminal Computer link
Operation frequency selectionby switching contacts
Frequency setting potentiometer External input signals 0 to 5, 0 to 10VDC 4 to 20mADC Digital signals (BCD, binary)
2 5
4 Option FR-A7AX
7 4
8 5 2
9 6 3
1 0
Operation with external signals
Operation with a parameter unit
Fig. 3.9 Operation method of inverter
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3.5.2 Operation procedure outline
The general procedure for "Operation with external signals" is as follows.
Power-on Function setting Start
When the start signal is turned on, an inverter starts and accelerates the motor. Terminals STF-SD on
Variable-speed operation is performed with the frequency setting signals.
The input side magnetic Set values of the functions contactor MC is turned on. required for the parameter unit. (For first-time operation)
The input side When the start signal is turned off, an inverter magnetic contactor MC is turned off. decelerates and stops the motor. Terminals STF-SD off
3.5.3 Concept of function setting
Multiple functions are provided with FREQROL-A700 series and a certain value is factory-set for those functions. Therefore, operations can be performed without setting functions. Set only the necessary functions according to the operation specifications. (1) To operate with factory setting values Function setting is not required. (2) Functions commonly set Functions to be used differ according to the operation specifications. The following functions are the major "functions commonly set".
Acceleration [Function number 7] Deceleration [Function number 8] Electronic thermal O/L relay [Function number 9]
Parameter No.
Torque boost (handle) Maximum frequency Minimum frequency Base frequency Multi-speed setting (high speed) Multi-speed setting (middle speed) Multi-speed setting (low speed) Acceleration time Deceleration time Electronic thermal O/L relay DC injection brake operation frequency DC injection brake operation time DC injection brake operation voltage Starting frequency Applied load selection
Screen display
Trq.Bst1 Max. F Min. F VFBase F PresetS1 Preset2F Preset3F Acc.T1 Dec.T1 SetTHM DCBr.F DCBr.T DCBr.V Start F Load VF
Setting range
0 to 30 0 to 120Hz 0 to 120Hz 0 to 400Hz 0 to 400Hz 0 to 400Hz 0 to 400Hz
0 to 3600 seconds/ 0 to 360 seconds 0 to 3600 seconds/ 0 to 360 seconds
Minimum setting unit 0.1 0.01Hz 6
Factory setting
4 3 2 (Note 1) 1
0 1 Basic function 2 3 4 5 6 7 8 9 10 11 12 13 14
120 60Hz (Note 2) 0Hz 60Hz 60Hz 30Hz 10Hz
0.1 second/ 0.05 second 0.1 second/ 0.05 second 0.01A 0.01Hz 0.1 second 0.1 0.01Hz 1
5 seconds 15 seconds (Note 3) 5 seconds/15 seconds (Note 3) Rated output current 3Hz 0.5 seconds 4 2 1 (Note4)
0 to 500A 0 to 120Hz, 9999 0 to 10 seconds, 8888 0 to 30 0.01 to 60Hz 0 to 5
0.5Hz 0
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(Note 1) The setting value depends on the inverter capacity and 6% is for 0.4K or 075K, 4% for 1.5K to 3.7K, 3% for 5.5K or 7.5K, 2% for 11K to 55K and 1% for 75K or more. (Note 2) The setting value depends on the inverter capacity and 120Hz is for 55K or less and 60Hz for 75K or more. (Note 3) The setting value depends on the inverter capacity and 5seconds is for 7.5K or less and 15 seconds for 11K or more. (Note 4) The setting value depends on the inverter capacity and 4% is for 7.5K or less, 2% for 11 to 55K and 1% for 75K or more.
(3) Parameter number and definition (Note) Pr. is an abbreviation of parameter.
Pr.0 Torque boost (manual) setting
● The motor torque in the low frequency range can be adjusted to the load.
Output voltage
Pr.3 Base frequency setting Pr.3 Base frequency
● The base frequency (reference frequency at the rated motor torque) can be set as desired within the range of 0 to 400Hz according to the rated motor torque.
Setting range of base frequency 100
Pr.0 Setting range Output frequency (Hz) Base frequency
Output voltage
Pr.1 Pr.2 Maximum/minimum frequency settings Pr.1
Maximum frequency
Pr.3 Base frequency
Minimum frequency
● The upper and lower limits of the output frequency can be clamped.
Output frequency
Pr.4 Pr.5 Pr.6 Multi-speed setting Pr.4 Multi-speed setting (high speed) Pr.5 Multi-speed setting (middle speed) Pr.6 Multi-speed setting (low speed)
● Each speed (terminal RH, RM or RL-SD) can be selected by merely switching external contact signals. ● Each speed (frequency) can be set to any value within the range of 0 to 400Hz while the inverter is running. Setting can also be made with the ▲ ▼ keys.
Maximum frequency
Minimum frequency
Output frequency
Frequency setting signal 5V (10V) (20mA)
1st speed (high speed) 2nd speed (middle speed) 3rd speed (low speed)
(Note) When setting the frequency of 120Hz or more, make setting in Pr.18.
Across RH-SD Across RM-SD Across RL-SD
(Note) 1. The multi-speed settings override the main speeds (across terminals 2-5, 4-5). 2. The multi-speed setting is available in the PU or
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external operation mode.
Pr.7 Pr.8 Acceleration/deceleration time setting Pr.7 Acceleration time Pr.8 Deceleration time Pr.20 Acceleration/deceleration reference frequency Pr.21 Acceleration/deceleration time increments
● For the acceleration time Pr.7, set the time taken to reach the setting value in the reference frequency Pr.20 from 0Hz. For the deceleration time Pr.8, set the time taken to reach 0Hz from the Pr.20 value. ● Use the acceleration/deceleration time increments Pr.21 to set the setting range and minimum setting increments. Setting value 0: 0 to 3600 seconds (minimum setting increment: 0.1 second) Setting value 1: 0 to 360 seconds (minimum setting value: 0.01 second)
Operation frequency
DC injection adjustment Pr.10 DC injection brake operation frequency Pr.11 DC injection brake operation time Pr.12 DC injection brake voltage
● By setting the DC injection brake torque (voltage) at a stop, the operation time and the operation starting frequency, the stopping accuracy of a positioning operation, etc. can be adjusted according to the load.
Output frequency
Pr.10 Operation frequency Time Pr.12 Operation voltage
DC injection brake voltage
Pr.11 Operation time
Pr.13 Starting frequency setting
Acceleration Pr.7
Pr.9 Electronic thermal O/L relay setting
● The current value (A) to protect the motor from overheat can 50Hz so that the motor can be in the optimum thermal condition. This feature provides the optimum protective characteristics, including reduced motor cooling capability, at low speed. ● Setting 0A makes the motor protective function invalid. (The output transistor protection of the inverter functions.) ● When using the Mitsubishi constant-torque motor, set any of 1, 13 to 18, 50, 53 or 54 in Pr.71 (Applied motor), select the 100% continuous torque characteristic at low speed, and then set the rated motor current in Pr.9 (Electronic thermal O/L relay). ● The factory setting value is set to [Rated output current of inverter]. However, 0.4K and 0.75K are set to 85% of the inverter rated current.
Setting range
be set as it is. Normally set the rated motor current value at
Output frequency
Deceleration Pr.8
● Frequency at a start can be set in the range of 0 to 60Hz.
(Hz) 60
Pr.13 0 Frequency setting signal(V) ON Time
Forward rotation
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Pr.14 Applied load selection
● The optimum output characteristic (V/F characteristic) for applications and load characteristics can be selected.
Pr.14 setting value 0 1 2 3 4 Constant torque load Reduced-torque load For torque elevators Signal terminals RT-SD. OFF across ON Constant torque load (same as when Pr.14=0) Reverse rotation boost for constant torque elevators 0% (same as when Pr.14=2) 5 Signal terminals RT-SD. OFF across ON Constant torque load (same as when Pr.14=0) Forward rotation boost for constant torque elevators 0% (same as when Pr.14=3) constant Reverse rotation boost 0% Forward rotation boost 0% Output characteristics
(Note) This parameter setting is ignored when Pr.80 or Pr.81 has been set to select the advanced magnetic flux vector control or the real sensorless vector control.
Setting value 0 (Factory setting) Setting value 4, 5(RT-SD is ON) For constant torque load (Conveyor, cart, etc.) For reduced-torque load (Fan, pump) Setting value 1
Output voltage
Output voltage
Pr.0 Base frequency Output frequency(Hz) Base frequency Output frequency(Hz)
Setting value 2 Setting value 4 (RT-SD is OFF)
For vertical lift load Forward rotation boost Reverse rotation boost
Setting value 3 Setting value 5 (RT-SD is OFF)
Setting value of Pr.0 0
For vertical lift load Setting value of Pr.0 Forward rotation boost 0 Reverse rotation boost
Output voltage
Output voltage
Forward rotation
Reverse rotation
Reverse rotation Base frequency Output frequency(Hz)
Forward rotation Base frequency Output frequency(Hz)
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3.5.4 Starting/Stopping methods
If a motor is not properly started/stopped, the inverter may not operate properly or may be damaged in the worst case. Correct
The inverter is started and The inverter is started and The inverter is started and stopped with the terminals stopped with the input side stopped with the output side (STF, STR). magnetic contactor (MC1). magnetic contactor (MC2).
MC1 Power-on (MC1 ON) R S T
MC1 Power-on (MC1 ON) R S T
MC1 Power-on (MC1 ON) R S T Start signal ON Across STF-SD ON MC2 U MC2 OFF STF SD
Operation procedure
Start signal
Start signal ON Across STF-SD ON STF SD
is kept ON. STF SD
Start signal OFF Across STF-SD OFF STF SD
Power-off (MC1 OFF)
Coasting to stop
Motor speed
N Coasting to stop
Motor speed
Motor speed
Motor speed/inverter output
t f
Output frequency
Output frequency
t f
Output frequency
t f Inverter trip
t STF MC1 ON ON OFF
t t t STF MC2 ON ON OFF
The inverter starts when the Frequently turning on and off When the MC2 is turned on, the terminals STF-SD are turned on the MC1 may damage the overcurrent protection is and decelerates to stop when inverter. activated and the inverter trips. they are turned off.
Fig.3.10 Starting/Stopping methods
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3.5.5 Start/stop with the input side magnetic contactor MC
(1) An inverter is not designed on the assumption that it is started/stopped with the input side magnetic contactor (MC1). (2) When the AC power supply is turned on by the input side magnetic contactor (MC1), a large inrush current flows to the large-capacity smoothing capacitor in the inverter. To suppress this current, a short-time rating control resistor is installed at the place shown in Fig. 3.11. In addition, a relay or magnetic contactor (MC3) is installed to short both ends of the resistor when charging the capacitor is completed. (3) When an inverter is frequently turned on/off using the input side MC, the repeated inrush current causes overheat of the control resistor and eventually breakage. If the relay or input side magnetic contactor (MC1) shorting the resistor is turned on in this state, a large inrush current flows into the smoothing capacitor through the converter elements (diodes) for charging. This uncontrolled inrush current damages the converter elements.
MC3 Converter MC1 Power supply
R Control resistor C Smoothing capacitor
Fig. 3.11 Converter circuit
(4) Such operation must be avoided since not only the lives of the converter elements but of the smoothing capacitor, the relay for shorting a control resistor and the magnetic contactor (MC3) are shortened. (5) When a motor is stopped by turning off the input side magnetic contactor (MC1), the regenerative brake proper to the inverter control is not operated. The motor coasts to stop. When an instantaneous power failure or a power failure occurs, the motor also coasts to stop.
Good to know for checking an inverter
For a machine which requires the motor (including the inverter) be shut off from the power supply at every operation end to prevent hazardous conditions, it is recommended to use the output side magnetic contactor (MC2) installed between the inverter and the motor for shutting off the motor from the power supply. (Note) Turn on the output side magnetic contactor (MC2) in the status of the inverter stop (output stop). (Turn off the MC2 after turning on the terminals MRS-SD.)
Inverter MC2 U V W Motor IM
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3.5.6 Inverter start during motor coasting
The inverter cannot be started during motor coasting. The following explains the reasons and precautions. (1) A residual voltage is generated in the motor when it coasts to stop. If the voltage is applied to the motor from the inverter in that status, the phases of the motor residual voltage (sine wave) and inverter output voltage (PWM) do not match and the overcurrent occurs. starting system on the commercial-power supply operation.)
(Reference: The overcurrent is also generated when switching from
is performed in the
(2) The inverter always outputs the starting frequency (variable according to 0.5Hz parameter) at start. If the motor is coasting at this time, the regenerative overcurrent occurs due to the rapid braking operation to decelerate the motor to the synchronous speed of the starting frequency. A regenerative overvoltage trip may occur. (3) Generally, an interlock, coating interlock timer, is provided with the sequence to prevent the inverter from being started during motor coasting. (4) To continue an operation without stopping the motor in the case of an instantaneous power failure, etc., the automatic restart after instantaneous power failure function is effective if selected.
3.5.7 Using method of motor with electromagnetic brake
The following shows the precautions and circuit example when the motor with brake is operated with an inverter.
BR BK Electromagnetic brake
NFB Power supply Tr F Stop Start
FREQROL Inverter
F F BR RES SD MRS BR CR Reset
For details, refer to Fig. 3.19.
Fig. 3.12 Circuit example of motor with brake
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(1) Provide the power supply for brake from the input side of the inverter. (2) To stop a motor with electromagnetic brake, turn off the inverter output by turning on the inverter output stop terminals MRS-SD. Otherwise, an overcurrent (OC3) may occur when the locked current flows to the motor at braking. (3) When a motor with brake is used, rattle may be heard according to the type of the brake during continuous operation at the low speed (30Hz or less). The motor can be used without trouble if used for the low-speed operation in a short time such as the positioning stop. (4) When an inverter is used with the 400V system power distribution, the operation circuit is controlled by stepping down to 400V/100V or 400V/200V via a step-down transformer Tr.
3.5.8 Frequency setting (select) signals and output frequency
The output frequency can be varied using the following methods.
• Continuously change the frequency setting signal (e.g. 0 to 5VDC, 4 to 20mA). (Hold down the ▲ or ▼ key to operate with the parameter unit.) • Change the frequency step-by-step by switching the multiple frequency setting potentiometers or
by switching the multi-speed selection terminals (RH, RM and RL). (Directly enter the frequency when the parameter unit is used to control.) (1) When the frequency setting signal is continuously varied
The relationship is proportional.
Output frequency
Acceleration/deceleration time ta set with the parameter unit
Output frequency
(Hz) 2.5 5V
Frequency setting signal
0 to
* If the frequency setting signal is started earlier than the acceleration/deceleration time setting value (ta), the acceleration/ deceleration time does not become shorter than ta.
Fig. 3.13 Variable time of frequency setting signal
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(2) When switching the multi-speed selection signals
• When switched simultaneously
Output frequency
• When switched at some interval
(2nd speed)
Output frequency
(2nd speed)
NFB (1st speed) The speed is reduced in this area. Inverter
(1st speed)
(Hz) t RL-SD ON
(Hz) t RL-SD ON to RM-SD ON (2nd speed)
(1st speed) t RL
t ON
Fig. 3.14 Change of output frequency at switching
Good to know for checking an inverter
When the motor speed does not reach the setting value, the causes may be as follows.
Inverter NFB R S T
POWER MON FUNC PrSET SHIFT
IM The memory of the frequency
7 4 1
8 5 2
9 6 3
is not corrected. <When the readings are checked> SD The setting values of "Maximum/Minimum frequency" Pr.1 / Pr.2. are improper The setting value of "Analog input selection" Pr.73 is improper. Terminals AU-SD are not connected for "Frequency at 20mA input". The settings of the calibration parameters "gain, bias"are improper. Pr.125 Pr.126 Pr.902 to Pr.905
10 2 5 The magnitude of the frequency setting signals differs. Measure the voltage across terminals 2-5.
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Good to know for checking an inverter When the motor remains stopped with the start signal turned on
(1) Check the main circuit. 1) Check that the power is supplied. 2) Check that the R or S phase of the power supply is not opened. 3) Check that the motor is securely connected to the inverter. (2) Check the input signal. 1) Check that the frequency setting signal is being input or not set to the zero level. 2) Check that the start signals of both forward and reverse rotation are not input. 3) Check that the "Reset" or "Output stop" signal is not input. 4) Check that the terminals AU-SD at 4 to 20mA input is turned on. (3) Check the function setting values. 1) Check that "Reverse rotation prevention" is not set.
2) Check that "Operation mode" is not set to the PU operation. 3) Check that each operation function is not set to 0 when used. "Multi-speed setting" "JOG frequency" Pr.15 4) Check that "Starting frequency" is not larger than the operation frequency. Pr.902, 904 Pr.13 5) Check that the "Bias" setting is proper. Pr.4 6, 24 27
(4) Others
• Check that the alarm lamp is not lit.
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3.5.9 Other operation methods
(1) Three-wire type (terminal STF, STR, STOP) The three-wire type connection is shown in Fig. 3.16. 1) Short the terminals STOP-SD to enable the start self-holding function. In this case, the forward/reverse rotation signal functions only as a start signal. 2) If the start signal terminals STF (STR)-SD are once shorted and then opened, the start signal is kept on, and either of the terminals which is shorted earlier is enabled to start the inverter. 3) The inverter is decelerated to stop by opening the signals STOP-SD once. For the frequency setting signal and the operation of DC injection brake at stop, refer to Section 2.7.2. Fig. 3.16 shows the three-wire type connection. 4) When the terminals JOG-SD are shorted, the signal of terminal STOP is disabled and the JOG operation has a priority. 5) Short the output stop terminals MRS-SD to deactivate the self-holding function.
NFB Power supply Forward rotation Reverse rotation Inverter STF STR SD
Power supply NFB Inverter
Forward rotation Reverse rotation
Output frequency
Output frequency
Terminals STF-SD (STR)
Start Stop
Fig. 3.15 Two-wire type connection example Fig. 3.16 Three-wire type connection example
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(2) When one motor is run by one inverter
"Operation preparation" OFF ON MC MC Inverter No.1 alarm signal B C Inverter No.2 alarm signal B C
F NFB T(Note)3 MC R Power supply S T Inverter No.1 V W B C 10 2 5 STF SD Normally closed Alarm signal Abnormally open Start signal IM U
Frequency setting potentiometer 2W1k
Earth (Ground) R Inverter No.2 S T V W STF SD B C Alarm signal IM U Motor
10 2 5
Up to three inverters are connectable.
Earth (Ground)
Fig. 3.17 When one motor is run by one inverter
For ratio operation
Frequency setting potentiometer 2W 1k Ratio setter 1/3W10k 10 2 5 2 5 Inverter No.2 Inverter No.1
(Note) 1. Using the parameter unit calibration functions, the output frequency of three inverters corresponding to a common command voltage value from the frequency setting potentiometer can be adjusted to match. 2. When more than two motors are mechanically connected, the load may be applied to one motor and an overload may occur.
The ratio setting can be skipped by setting the gain/bias of the parameter unit calibration functions.
3. When the power supply is 400V class, install a control transformer.
Fig. 3.18 For ratio operation
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(3) Motor with brake
BMC Mechanical brake
MC Forward rotation Reverse rotation Second function Low speed High speed Output stop RES F R H
Centrifugal switch
Make sure to consider the installation of the various limit switches and the zero notch interlock that are not provided in this circuit example.
RL Plug-in option H MRS MRS RH FR-A7AR RUN 1A 1C SU 2B 2C 3B 3C
Install a step-down transformer when the power supply is 400VAC.
Emergency stop HB HC TH1 TH2 R F F R Reverse rotation Forward rotation MC Input MC
Forward rotation
Reverse rotation
High speed Y13 (ZERO)
High speed
Brake closed
Output stop
Operation check
Fig. 3.19 Motor with brake
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This chapter describes how the power source and its system to which an inverter is connected are affected by the harmonics generated by the inverter. Then, it examines what measures should be actually taken against the harmonics with judging the effect to peripheral devices with the harmonic amount generated by inverters. This chapter also describes how the fluctuation of the power supply (instantaneous power failure, voltage drop, etc.) affects an inverter. It is important to understand how an inverter and motor work. POINTS for understanding! 1. Difference between harmonics and noise 2. Influx path and magnitude of the harmonic current 3. Harmonic suppression measure guideline and the measures 4. Harmonic permissible values of peripheral devices (capacitor and generator) 5. Movement of an inverter and motor at the instantaneous power failure (including the instantaneous voltage drop)
4.1 Harmonics
The harmonics are defined as a fundamental wave (generally, power supply frequency) with an integral multiple frequency. One fundamental wave combined with multiple harmonics is called a distortion (Refer to Fig. 4.2). Distorted waves generally include the harmonics of high frequency band (kHz to MHz order). The frequency band handled as the harmonics of a power distribution system is 40th to 50th (until 3kHz), and it should be regarded as a different problem from a high frequency band with a random aspect. For example, the radio disturbance or noise (refer to Chapter 5) caused by a personal computer should be treated as a local problem of hardware. Therefore, its influences and measures are different from those of the harmonics generated from an electrical circuit network. This point must be made clear.
i = io + in sin (2 fnt + n)
n = 1, 2, 3, …… f = Fundamental frequency
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i1 Fundamental wave
i1 i3
i2 Second harmonics
i3 Third harmonics
Distorted wave
Fig. 4.1 Fundamental wave and harmonics Fig 4.2 Distorted wave Table 4.1 Difference between harmonics and noise Item Frequency Source Cause Environment Quantitative understanding Generated amount Immunity of affected device Examples of safeguard Harmonics Normally 40th to 50th or less, 3kHz or less Converter part Communication of rectifying circuits To wire paths, power impedance Logical computation is possible Approximately proportional to load capacity Specified in standards for each device. Install a reactor (L). Noise High frequency (Several tens of kHz to MHz order) Inverter part Switching of capacitors Across spaces, distance, laying paths Occurs randomly, quantitative understanding is difficult. According to current fluctuation rate (larger with faster switching) Differs according to maker's device specifications. Increase the distance( ).
4.2 Rectifying Circuit and Characteristics of Generated Harmonics
The sources of the generated harmonics are a rectifier, AC power regulator, etc. The converter in a general-purpose inverter consists of rectifying circuits, which generate many harmonics. There are various rectifying circuits depending on the main circuit pattern as shown in Table 4.2. For the most general-purpose inverters, three-phase bridge is adopted. The theoretical harmonic occurrence order (n) is n = PK±1 (P = number of pulses, K=1, 2, 3...). Three-phase bridge type general-purpose inverters generate 5th, 7th, 11th, 13th...harmonics. The magnitude of harmonics (harmonic contents) is 1/n, which means that the generated amount becomes smaller as the harmonic order becomes larger. One-phase power input inverters generate the harmonics with the order of 4K±1 (3rd, 5th, 7th, 9th...).
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Circuit name 1-phase bridge
Table 4.2 Rectifying circuit types and harmonics Basic circuit Harmonic order Harmonic contents
Main devices
n = 4K ± 1 K = 1,2, …
AC electric train
1-phase hybrid bridge
n = 2K ± 1 K = 1,2, …
3-phase bridge
n = 6K ± 1 K=1,2, …
Inverter DC electric train Substation Electrochemistry Other general use
3-phase hybrid bridge
n = 3K ±1 K = 1,2, …
Kn: Coefficient determined by an angle of control delay, angle of communication overlap, etc.
4.3 Shunt of Harmonic Current
When the harmonics are considered in the power distribution system, the power source of the harmonics is not the commercial power supply but the harmonic occurrence source (converter for general-use inverters). The commercial power supply (low and high-voltage power transformers) becomes a part of the load for the harmonics. Accordingly, the harmonic equivalent circuit of the power distribution system diagram shown as an example in Fig. 4.3 will be the one shown in Fig. 4.4. The harmonic current generated by the inverter In (In = I2 + I3+ I4 + ... if n is an order) shunts in proportion to 1/Z, which is the inverse proportion of the impedance of the power transformer (ZL = RL + jnX L) and the devices that is connected in parallel with the transformer (motor B and capacitor in the example of Fig. 4.3), that is to say, the impedances of the motor B (ZM = RM + jnXM) and capacitor (ZC = jnXr - jXc/n).
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Commercial power supply
Power transformer XL RL ILn In Inverter IMn Xr Xc Capacitor ICn
Inverter In
ILn nXL ZL RL
IMn nXM ZM RM
ICn nXr ZC Xc/n
Power transformer
Motor B Capacitor
Fig. 4.4 Harmonic equivalent circuit (No.1)
M Motor A
M Motor B
Fig. 4.3 Power distribution system diagram (No.1) Fig. 4.5 shows an example of a power distribution system diagram including a high-tension circuit. In this example, loads on the low-tension side (motors, etc.) are abbreviated since the harmonics generated in the inverter mostly flow into the power transformer for the enormous load impedance ( Z M) in comparison with the power transformer impedance (ZL). The harmonic current on the high-tension side In is the total harmonic current value of the low-tension inverter divided by the transformation ratio.
Commercial power supply Xs, Rs ILn m2 In = m1 (In1+In2) XL RL Transformer Primary m1[V] Secondary m2[V] Xr Xc In1+In2 Capacitor Icn
ILn = In ICn = In
Zc Zs+Zc Zs Zs+Zc
Transformer nXL RL
nXs Zs
nXr Zc Xc/n
In1 Inverter 1
In2 Inverter2
Rs Inverter Power supply
Fig. 4.5 Power distribution system diagram (No.2) Good to know for checking an inverter
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Fig. 4.6 Harmonic equivalent circuit (No.2)
▪ Impedance Z of inductive loads (motors, transformers, etc.)
Z = R + jωX = R + j2πfX
f0:Fundamental frequency)
= R + j2πf0nX = R + n (j2πf0X) ▪ Impedance Z of capacitive loads (capacitors)
Z = - j 1 C = - j 1 2 fC = - j 1 2 f0nC = 1 n (- j 1 2 f0 C )
▪ The current tends to flow to the smaller impedance, and a capacitive impedance element (power
factor correction capacitor) may magnify the harmonics. When the harmonics are considered as a problem, the following can be said from the above: 1) The impedance on the power supply side ZS is represented by the short-circuit capacity on the power supply system and is not less affected by other factors as the power capacity is larger. 2) The inductive loads can be neglected since they have higher impedance than the harmonics. 3) What should be considered is only capacitive loads such as a power factor correction capacitor. Good to know for checking an inverter (a) If a power factor improving reactor is installed, the harmonic components decrease with the effect equivalent to the larger impedance of the inverter power supply side. The impedance of a reactor is well over that of a power transformer. The gap due to the capacity of power transformers is reduced to almost zero. (b) The harmonic components without a power factor improving reactor installed highly depend on the capacity of the power transformer (including a line impedance). (c) When the inverter output frequency or motor load factor is low, the harmonic contents against the inverter input current become higher. However, the absolute value of the harmonic current does not become higher than at full load since the input current itself is small. For the reduced-torque loads such as a fan and pump, calculate the harmonic current under the conditions of the maximum setting frequency, 50Hz or 60Hz.
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4.4 Harmonic Suppression Guideline
Harmonic currents flow from the inverter to a power receiving point via a power transformer. The harmonic suppression guideline was established to protect other consumers from these outgoing harmonics. The three-phase 200V input specifications 3.7kW or less are previously covered by "Harmonic suppression guideline for household appliances and general-purpose products" and other models are covered by "Harmonic suppression guideline for consumers who receive high voltage or special high voltage". However, the general-purpose inverter has been excluded from the target products covered by "Harmonic suppression guideline for household appliances and general-purpose products" in January 2004 and then the guideline was abolished on September 6, 2004. All capacity models of general-purpose inverter used by specific consumers are now covered by "Harmonic suppression guideline for consumers who receive high voltage or special high voltage" (hereinafter referred to as "Guideline for specific consumers").
4.4.1 Harmonic suppression guideline for consumers who receive high voltage or special high voltage
The maximum amount of generated harmonics must be suppressed under the following values per 1kW contract power. Table 4.3 Maximum values of outgoing harmonic currents per 1kW contract power (Unit: mA/kW) Received power 5th 7th 11th 13th 17th 19th 23rd Over voltage 23rd 6.6kV 3.5 2.5 1.6 1.3 1.0 0.9 0.76 0.70 22 1.8 1.3 0.82 0.69 0.53 0.47 0.39 0.36 33 1.2 0.86 0.55 0.46 0.35 0.32 0.26 0.24 66 0.59 0.42 0.27 0.23 0.17 0.16 0.13 0.12 77 0.50 0.36 0.23 0.19 0.15 0.13 0.11 0.10 110 0.35 0.25 0.16 0.13 0.10 0.09 0.07 0.07 154 0.25 0.18 0.11 0.09 0.07 0.06 0.05 0.05 220 0.17 0.12 0.08 0.06 0.05 0.04 0.03 0.03 275 0.14 0.10 0.06 0.05 0.04 0.03 0.03 0.02
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The harmonic contents for each circuit type are shown in the following table. Table 4.4 Harmonic contents Circuit type 3-phase bridge ▪ 6-pulse converter ▪ 12-pulse converter ▪ 24-pulse converter 3-phase bridge (capacitor smoothing) ▪ Without reactor ▪ With reactor (AC side) ▪ With reactor (DC side) ▪ With reactors (AC, DC sides) 1-phase bridge (capacitor smoothing) ▪ Without reactor ▪ With reactor (AC side) 5 17.5 2.0 2.0 7 11.0 1.5 1.5 11 4.5 4.5 1.0 13 3.0 3.0 0.75 17 1.5 0.2 0.2 19 1.25 0.15 0.15 (Unit: %) 23 25 0.75 0.75 0.75 0.75 0.75 0.75
65 38 30 28
41 14.5 13 9.1
8.5 7.4 8.4 7.2
7.7 3.4 5.0 4.1
4.3 3.2 4.7 3.2
3.1 1.9 3.2 2.4
2.6 1.7 3.0 1.6
1.8 1.3 2.2 1.4
50 6.0
24 3.9
5.1 1.6
4.0 1.2
1.5 0.6
1.4 0.1
― ―
― ―
1) Calculation method of outgoing harmonic current (a) Calculate the rated capacity [kVA]. The rated capacity is used for calculation of 6-pulse equivalent capacity to determine the application of "Harmonic suppression guideline for consumers who receive high voltage or special high voltage". Adjust the rated capacity [kVA] and the fundamental wave current [A] according to the motor capacity regardless of the installation of a reactor. ● It should be noted that the rated capacity Motor Fundamental Rated capacity capacity above is used to determine capacity wave current [A] [kVA] the application of the harmonic [kW] 200V 400V 200V 400V suppression guideline and is different 0.4 1.61 0.81 0.57 from the power supply capacity (power 0.75 2.74 1.37 0.97 1.5 5.50 2.75 1.95 transformer, etc.) required for actual 2.2 7.93 3.96 2.81 inverter drive. 3.7 13.0 6.5 4.61 For the power supply capacity, 1.3 to 5.5 19.1 9.55 6.77 1.6 times as large as the above rated 7.5 25.6 12.8 9.07 capacity (correct values are described 11 36.9 18.5 13.1 in a catalog of the inverter). 15 49.8 24.9 17.6 18.5 61.4 30.7 21.8 (b) Calculate the 6-pulse equivalent 22 73.1 36.6 25.9 capacity using the conversion coefficient 30 98.0 49.0 34.7 37 121 60.4 42.8 Ki. 45 147 73.5 52.1 ● 6-pulse equivalent capacity 55 180 89.9 63.7 = Rated capacity × 75 245 123 87.2 conversion coefficient Ki [kVA] 90 293 147 104 The conversion coefficient Ki is: 110 357 179 127 Circuit type Ki 132 216 153 ― ― Without reactor 3.4 160 258 183 ― ― With AC reactor 1.8 200 323 229 ― ― With DC reactor 1.8 220 355 252 ― ― With AC/DC reactors 1.4 250 403 286 ― ― 319 450 Table 4.6 Conversion coefficient Ki 280 ― ― Table 4.5 Fundamental wave current and rated
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(c) Convert to the rated current of the received power voltage. ● Rated current value converted to the received power voltage = fundamental wave current × (200V or 400V/received power voltage) [A] For the fundamental wave current, the value in Table 4.5 must be used. (d) Calculate the outgoing harmonic current of each order from the harmonic contents. ● Outgoing harmonic current = rated current value converted to the received power voltage × operation ratio × harmonic contents 2) Calculation example When a 30kW/400V motor is driven without a reactor by the inverter FR-A740-30K ▪ The fundamental wave current of the motor is 49.0A.from Table 4.5. ▪ The rated capacity is 34.7 [kVA].from Table 4.5. ▪ 6-pulse equivalent capacity = rated capacity × conversion coefficient Ki (Table 4.6) = 34.7 × 3.4 = 118 [kVA] Calculate the outgoing harmonic current by the following procedure. ▪ Rated current value converted to the received power voltage = fundamental wave current × (400V/received power voltage) = 49.0 × 400/6600 = 2.97 [A] ▪ Outgoing harmonic current = rated current value converted to the received power voltage × operation ratio × harmonic contents (Table 4.4) makes the following table. Assume that the operation ratio is 50%. For example, if the order is 5th, 2.97 × 0.5 × 0.65 = 965mA Order 5th 7th 11th 13th 17th 19th 23rd 25th Guidelin Outgoing current [mA] 965 609 126 114 64 46 39 27 e setting Maximum value of value outgoing current 3.5 2.5 1.6 1.3 1.0 0.9 0.76 0.70 ← [mA/kW] Therefore, if the contract power is 965/3.5 = 275kW or less, a harmonic suppression measure must be taken. (1) Measures against harmonics To suppress the harmonics on the inverter, the following measures can be taken. ● High power factor converter : The high power factor converter reshapes an input current waveform into a sine wave and greatly decreases the generated harmonics from a combined inverter. ● AC reactor ● DC reactor ● With AC/DC reactors : Installing an AC reactor on the inverter power supply side suppresses the harmonics with the larger impedance. : Installing the DC reactor on the inverter DC circuit suppresses the harmonics with the larger impedance. : Installing an AC reactor on the power supply side and a DC reactor larger on the DC circuit suppresses the harmonics with the impedance. [A]
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Application of each measure A) High power factor converter This method greatly decreases the with
Outside box
● Circuit example of high power factor converter
generated harmonics by switching a rectifying circuit (converter) capacitors to control a current waveform for the more accurate sine wave. If K5 = 0, the guideline can be cleared without other measures. This is the most ideal method since it decreases the generated harmonics themselves of an inverter. B) AC reactor Installing an AC reactor on the inverter power supply side suppresses larger the line
Motor ACL
ACL2 High power factor converter P N Motor
● Connection example of ACL reactor
harmonics impedance.
(a) Features ▪ The AC reactor can be used as a power factor improving reactor when using an inverter since it improves the input power factor to approximately 0.88. ▪ This is the most typical method among the measures against the harmonics. (b) Selection method Select a model according to the motor capacity connected to an inverter.
Basic model name Capacity Motor capacity [kW] 200V:None 400V:H
Voltage class
(c) Precautions ● A relatively large voltage drop (approx. 2%) occurs on the power supply side, and it may cause the insufficient torque of a motor. ● When installing an AC reactor does not clear the guideline, another measure must be taken together.
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(d) Calculation example (1) When FR-HAL-H30K (AC reactor) is connected to the power supply according to the motor capacity under the condition of the item 2), the rated capacity is: 34.7 [kVA] from Table 4.5 Calculate the outgoing harmonic current by the following procedure. ▪ 6-pulse equivalent capacity = rated capacity × conversion coefficient Ki (Table 4.6) = 34.7 × 1.8 = 62.5 [kVA] ▪ Rated current value converted to the received power voltage = fundamental wave current × (400V/received power voltage) = 49.0 × 400/6600 = 2.97 [A] ▪ Outgoing harmonic current = rated current value converted to the received power voltage × operation ratio × harmonic contents (Table 4.4) makes the following table. Assume that the operation ratio is 50%. For example, if the order is 5th, 2.97 × 0.5 × 0.38 = 564mA Order 5th 7th 11th 13th 17th 19th 23rd 25th ← Outgoing current [mA] 564 215 110 50 48 28 25 19 Guideline Maximum value of setting outgoing current 3.5 2.5 1.6 1.3 1.0 0.9 0.76 0.70 value [mA/kW] Therefore, if the contract power is 564/3.5 = 161kW or less, a harmonic suppression measure must be taken. (This is only for the 5th.) C) DC reactor Installing the DC reactor on the inverter DC circuit suppresses the harmonics with the large impedance. ● Connection example of DCL
(a) Features ▪ The AC reactor can be used as a power factor improving reactor when using an inverter since it improves the input power factor to approximately 0.93. ▪ The DC reactor is advantageous for the little influence from the insufficient torque of a motor since it is connected to the DC circuit so that the voltage drop occurs only for the DC resistance (1% or less). ▪ The DC reactor is smaller and lighter than the AC reactor and has the better power factor improving effect.
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(b) Selection method Select a model according to the motor capacity connected to an inverter.
Basic model name Capacity Motor capacity [kW] 200V:None 400V:H
Voltage class
(c) Precautions ● The models that are not equipped with P and P1 terminals are not supported since the DC reactor is connected to the DC circuit of an inverter. Supported models are as follows. ▪ All models of FREQROL-A700, A500, F700, F500, E500 and S500 (excluding 1-phase 100V class) ● When installing an DC reactor does not clear the guideline, another measure without reactors must be taken. (d) Calculation example (1) When FR-HEL-H30K (DC reactor) is connected between P-P1 according to the motor capacity under the condition of the item 2) ▪ The rated capacity is 34.7 [kVA].from Table 4.5. ▪ 6-pulse equivalent capacity = rated capacity × conversion coefficient Ki (Table 4.6) = 34.7 × 1.8 = 62.5 [kVA] Calculate the outgoing harmonic current by the following procedure. ▪ Rated current value converted to the received power voltage = fundamental wave current × (400V/received power voltage) = 49.0 × 400/6600 = 2.97 [A] ▪ Outgoing harmonic current = rated current value converted to the received power voltage × operation ratio × harmonic contents (Table 4.4) makes the following table. Assume that the operation ratio is 50%. For example, if the order is 5th, 2.97 × 0.5 × 0.3 = 446mA Order 5th 7th 11th 13th 17th 19th 23rd 25th ← Outgoing current [mA] 446 193 125 74 70 48 45 33 Guidelin Maximum value of outgoing current 3.5 2.5 1.6 1.3 1.0 0.9 0.76 0.70 e setting value [mA/kW] Therefore, if the contract power is 446/3.5 = 127kW or less, a harmonic suppression measure must be taken. (This is only for the 5th.) D) With AC/DC reactors Installing an AC reactor on the power supply side and a DC reactor on the DC circuit suppresses the harmonics with the larger impedance.
● Combination example
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(a) Features Combining the AC and DC reactors decreases the harmonic contents as shown in Table 4.4 and heightens the effects on harmonic suppression. (b) Selection method Select an AC reactor and a DC reactor respectively according to the motor capacity. Refer to the items B) and C) for the details. (c) Precautions ● A relatively large voltage drop (approx. 6%) occurs on the power supply side, and it may cause the insufficient torque of a motor. ● When installing AC/DC reactors does not clear the guideline, another measure without reactors must be taken . (d) Calculation example (1) When FR-HAL-H30K is connected for an AC reactor and FR-HEL-H30K is connected for a DC reactor under the conditions of the item 3) ▪ The rated capacity is 34.7 [kVA].from Table 4.5. ▪ 6-pulse equivalent capacity = rated capacity × conversion coefficient Ki = 34.7 × 1.4 = 48.6 [kVA] Since this value is less than 50 [kVA] (received power voltage: 6600V), it is not applied to the guideline and the measures against the harmonic suppression are not required.
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(3) Outline of the measures against harmonics The following table outlines the principle and characteristics of the methods to control and absorb the harmonics. No. 1) Item
Reactor for inverter (FR-HAL, HEL)
Installing an AC reactor on the power supply side of an inverter or a DC reactor on its DC side or both to suppress the harmonic currents with a large circuit impedance. The converter circuit is switched to convert an input current waveform into a sine wave, suppressing the harmonic current substantially. Connect to the inverter on the DC side. The power factor improving capacitor has small impedance against the harmonics. When used with a series reactor, the power factor improving capacitor has an effect of absorbing harmonic currents. Install on the high or low voltage side. When two or more transformers are connected with a phase angle difference of 30 as in Y- , - combination, an effect corresponding to 12 pulses, reducing low-degree harmonic current can be obtained since the peak current is suppressed for the difference of timings. The AC filter has the same effects as the power factor improving capacitor. A capacitor and a series reactor are used together to reduce impedances at specific frequencies (orders), producing a great effect of absorbing harmonic currents. This filter detects the current of a circuit generating a harmonic current and generates a harmonic current equivalent to a difference between that current and a fundamental wave current to suppress a harmonic current at a detection point.
Effects, etc.
The harmonic current is suppressed to approximately half.
High power factor converter (FR-HC)
The harmonic current can be suppressed to almost zero.
Installation of power factor improving capacitor
Installing on the low voltage side has more absorbing effect.
Transformer multi-phase operation
Even when the capacity combination is different from Y- or - , the effect equivalent to 12 pulses can be expected, suppressing approximately half of the harmonic current. Substantial effect on suppression. (The guideline can be cleared.)
AC filter
Active filter
Substantial effect on suppression. (The guideline can be cleared.) The power factor improving effect can also be expected since the filter compensates the entire waveform.
The above procedures are: ● More advantageous in suppression effect in the order of 6) → 5) → 4) → 3) → 2) → 1). ● More advantageous in cost performance in the order of 1) → 2) → 3) → 4) → 5) → 6).
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For consumers other than specific consumers For consumers to whom "Harmonic suppression guideline for consumers who receive high voltage or special high voltage" is not applied, Japan Electrical Manufacturer's Association established JEM-TR226 "Harmonic suppression guideline of the general-purpose inverter (input current of 20A or less) for consumers other than specific consumers" as technical information using the conventional guidelines as a reference for promoting the comprehensive harmonic suppression. This guideline is established for consumers to take all possible measures against the harmonics for the inverter itself the same as before. For compliance to "Harmonic suppression guideline of the general-purpose inverter (input current of 20A or less) for consumers other than specific consumers" Available models Input power supply 1-phase 100V 1-phase 200V 3-phase 200V Applied motor capacity 0.75kW or less 2.2kW or less 3.7kW or less Measure Connect the AC reactor or DC reactor recommended in a catalog or an instruction manual.
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4.5 Influences of Harmonics to Peripheral Devices and Measures
4.5.1 Power factor correction capacitor
A capacitor prompts the heat deterioration of inductives and insulators and causes a burnout or breakdown of them in the long run when the harmonics overlapped to the fundamental wave current causes the temperature rise for the increase of losses and the overheat for the increase of the current effective value. For the power factor correction capacitor, the capacity for overvoltage and overcurrent is specified by JIS Standards. For the high voltage power factor correction capacitor, JIS-C4902 specifies 130% or less of the rated current. For the low voltage power factor correction capacitor, JIS-C4901 specifies so. When the permissible values are exceeded, the capacity must be changed or installing or changing a series reactor must be examined. The harmonic current flowing into a capacitor can be calculated from the following formula. (Refer to Formula (4.6).)
ZS ZS + ZC RS + jnXS RS + jnXS + jnXr - jXc/n (4.2)
Icn = In
= In nXs
= In
n(Xs + Xr) - Xc/n
If the capacitor fundamental wave current is I C1, the capacitor effective current I C is:
Ic =
Ic2 +
The judgment conditions are: For the low voltage power factor correction capacitor For the high voltage power factor correction capacitor Ic1 1.3 > Ic Ic1 1.3 > Ic (4.4) ( 4.5)
Good to know for checking an inverter The possible measures for suppressing the harmonic current to a capacitor as follows. (a) Install a power reactor improving DC reactor on the DC side of the inverter or a power factor improving AC reactor on the primary side to suppress the generated harmonic amount. (b) Use a capacitor with a series reactor. A capacitor with a series reactor is available with 6%, 8% or 13% of reactance. Avoid the series resonance for the selection. (c) Receive the power from a large capacity power supply to decrease the harmonic impedance of the power supply.
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4.5.2 Private generator
When the n-th harmonic current flows into a private generator, the rotating magnetic field n times as much as that of the fundamental wave is generated. The rotating magnetic field links the positive phase sequence harmonics when the speed is n-1 times the speed of a rotor and it links the negative phase sequence harmonics when the speed is n+1 times the speed of a rotor. This causes an inductive current in the damper winding or field winding, which may result in the output loss, life shortening, or breakdown. These influences from the harmonics can be calculated as an equivalent negative phase sequence current on the assumption that the loss by the harmonic current equals the loss by the negative phase sequence current. Various standards specify the negative phase sequence permissible value of a generator. JEM1354 specifies it as 15% or less.
n 2 (4.6)
Equivalent negative phase sequence current =
(In - 1 + In + 1) ) 2
Good to know for checking an inverter The possible measures for suppressing the harmonics to a generator are as follows. (a) Install a power reactor improving AC reactor on the primary side of the inverter or a power factor improving DC reactor on the DC side to suppress the generated harmonic amount. (b) Order a generator with a large negative phase sequence current permissible value. (Consulting a manufacturer is recommended since a large-capacity generator is designed according to ordered specifications.) (c) Restrict the inverter load used for the generator.
4.6. Influence of an instantaneous power failure to the inverter
When a power failure occurs, the power voltage from the control circuit used to control an inverter stops. To prevent the control malfunction, the instantaneous power failure protection is activated to stop the inverter output and maintain the output stop status. This protective operation differs according to the length of the instantaneous power failure. The explanation is given below using FREQROL-A700 series as an example.
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4.6.1 Inverter operations according to the instantaneous power failure
(1) When an instantaneous power failure is within 15ms The protective function is not activated and the operation continues normally.
Within 15ms Power supply
Inverter output (f) Motor speed (N)
(2) When an instantaneous power failure is longer than 15ms and shorter than 100ms The protective function is activated and the inverter output stops. (The motor coasts to stop.)
15ms to 100ms
Power supply 15ms
f N Operation continues t
f f N N
Output shut-off The motor coasts to stop.
Fig. 4.7 Instantaneous power failure within 15ms
Alarm output/display
Fig. 4.8 Instantaneous power failure longer than 15ms and shorter than 100ms (3) Instantaneous power failure longer than 100ms The inverter is automatically reset by the power restoration and becomes ready for resuming an operation. [Point to notice] When the start signal (STF, STR) is on, the inverter restarts with the power restoration. If a motor is coasting at this time, the overvoltage or overcurrent protection is activated and a trip occurs. To restart the inverter with the power restoration, use the instantaneous power failure restart function. (This function is available for FREQROL-A700 series as standard. However, the restart function is not factory-set. Set "0" in Pr. 57.) See Section 4.6.3 for details on the automatic restart after instantaneous power failure function
Power supply
100ms or longer t 15ms
f N
f N Output shut-off The motor coasts to stop.
Alarm output/display does not appear.
Fig. 4.9 Instantaneous power failure longer than 100ms
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Inverter peripheral circuit instantaneous power failure
(1) When magnetic contactors are not installed in the primary or secondary side of the inverter
NFB Inverter RA STF SD M
When an instantaneous power failure is short and the relay RA does not trip (the start signal STF is still ON), the inverter operates as shown in Section 4.6.1. When an inverter stops the output due to an instantaneous power failure and the motor coasts, the automatic restart after instantaneous power failure operation must be used or the start signal must be turned off by inverter output stop. (2) When a magnetic contactor (MC) is installed in the primary side of the inverter
NFB MC RA Inverter STF SD M
When an instantaneous power failure is short and both magnetic contactor MC and relay RA do not trip, the same as in (1) is applied. When only the magnetic contactor MC trips, the motor coasts to stop. The MC must be switched on after the coasting to a stop of the motor (a free run interlock timer is required) to restart the inverter after the power is restored. (3) When a magnetic contactor (MC) is installed in the secondary side of the inverter
NFB RA Inverter STF SD
When an instantaneous power failure is short and both magnetic contactor MC and relay RA do not trip, the same as in (1) is applied.
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When only the magnetic contactor MC trips, the motor coasts to stop. The inverter may continue the output depending on the instantaneous power failure time. Otherwise, only the inverter restarts after the inverter initial reset by power restoration. Therefore, switching on the MC directly starts the motor with the ongoing inverter output frequency, and the inverter may trip due to the overccurent. (4) When magnetic contactors (MC) are installed in both primary and secondary sides of the inverter
MC 1 Inverter RA STF SD
The same as in (2) and (3) is applied. Good to know for checking an inverter (a) Even if an instantaneous power failure occurs at the receiving end, a (perfect) instantaneous power failure does not always occur at the low voltage side, i.e., the inverter input terminals (R, S and T). Most cases are instantaneous voltage drops. (b) The inverter has the instantaneous power failure protection function and the undervoltage protection function. The undervoltage protection function is activated when the voltage in the inverter DC circuit below a certain level continues for a certain period. When an instantaneous power failure occurs at the power supply, the protection function is activated for some inverters depending on the load output (kW). If the load output is small, inverters may continue the operation. (c) Once a magnetic contactor or relay is switched on, it may not trip with an instantaneous voltage drop. Generally, it trips at the voltage of 30 to 50% or less of the coil rating.
4.6.3 Automatic restart after instantaneous power failure control
(1) Commercial power supply switchover, automatic restart after instantaneous power failure function
These functions are effective when the number of motor connected to an inverter is one. They do not work when multiple motors are used.
▪ Commercial power supply switchover.......................To switch from the commercial operation to the inverter operation, the inverter can be started without a motor stopped but with coasting. ▪ Automatic restart after instantaneous power failure.. When an instantaneous power failure occurs, a motor does not need to be stopped to continue the operation after the power restoration.
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(2) Operations of the automatic restart after instantaneous power failure function (a) When the power supply to a motor is switched off, the motor coasts. (b) When the DC voltage is applied to the coasting motor from the inverter, the DC current flows in the motor. (Refer to A) in Fig. 4.10.) This DC current includes the ripple at the frequency proportional to the motor speed. (c) The CPU takes in the signal from a current detector to count the frequency for the ripple and determines the motor speed. (d) The inverter outputs the signal with the frequency according to the motor speed. (Refer to B) in Fig. 4.10.) Then, the inverter operation is restarted, controlling the start current of the motor by gradually increasing the output voltage.
Power supply voltage
0 60Hz
Output frequency B
0 1800r/min
Motor coasting
Motor speed
Motor current
DC voltage applied A
Instantaneous power failure time
Resetting time
Reduction voltage time
Acceleration time
600ms 140ms
Speed detection time
Fig. 4.10 Example of automatic restart after instantaneous power failure operation
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When the automatic restart after instantaneous power failure function is equipped (Example: FREQROL-A700 series)
NFB RA Inverter STF SD CS SD M
Fig. 4.11 Wiring of automatic restart after instantaneous power failure function Short between CS-SD to use the automatic restart after instantaneous power failure function. Functions for good to know Power-failure deceleration stop function When an instantaneous power failure occurs, a motor usually coasts. However, the power-failure deceleration stop function decelerates a motor to stop using the residual bus voltage. If the power is restored during the deceleration for power failure, a mode can be selected to accelerate the motor again.
Power supply
Output frequency
Deceleration for power failure Stop for power failure Time
Instantaneous power-failure operation continuation function This function makes the operation continue using the regenerative energy generated by deceleration after detecting an instantaneous power failure. After the power is restored, it accelerates the motor to the command frequency and continues the operation. The inverter will trip if enough regenerative energy is not given from the motor due to the small load inertia. In this case, use the automatic restart after instantaneous power failure function.
Instantaneous power failure Power supply Output frequency
Deceleration for power failure
Reacceleration Time
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Along with the spread of electrical devices, the troubles caused by noise tend to increase. Since the inverter generates the noise from the operation principle, it may affect the adjacent devices. The degree of the effect varies according to the inverter control system, noise capacity of external device, laying condition of wiring, installation distance, grounding method, etc. When installing the devices described below near the inverter, it is recommended to take the following measures according to the condition. [Devices to be taken the measures against noise] Sensors (proximity switch, etc.), video cameras (ITV, image scanner, etc.), wireless radios (including an AM radio), acoustic devices (microphone, video, audio, etc.), CRT display and medical equipments [Devices better to be taken the measures against noise] Measuring equipments and internal telephones
5.1 Principle of Noise Generation
As described in Chapter 2, the output voltage waveform is controlled by switching the DC voltage at high speed in the inverter. The magnified output waveform is as shown in Fig. 2.17 of Chapter 2. Since the steep rise and drop include lots of high frequency components, these components are the noise source. The noise generated here and the harmonics mentioned in Chapter 4 are sometimes confused since both of them affect other electrical equipment. Generally, however, the harmonics commonly refer to waves with a frequency between 40th and 50th (2.4 to 3kHz) whereas noise commonly refers to waves with a frequency of tens of kilohertz or higher.
Fig. 5.1 Example of inverter output voltage waveform (When using the power supply of 200V class)
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5.2 Noise Types and Propagation Paths
Inverter-generated noises are largely classified into those radiated by the cables connected to the inverter and inverter main circuits (I/O), those electromagnetically and electrostatically induced to the signal cables of the peripheral devices close to the main circuit power supply, and those transmitted through the power supply cables. The types of noise are shown in Fig. 5.2 and the paths of noise in Fig. 5.3.
Noise directly radiated from inverter
Noise directly radiated from power supply cable
Noise directly radiated from motor connection cables
Inverter generated noise
Air-propagated noise 空中伝播ノイズ
Electromagnetic 電磁誘導ノイズ induction noise
Electrostatic induction noise
Noise propagated through power supply cable
Undesirable noise from earth (ground) cable by leakage curren
Cable-propagated noise
Fig. 5.2 Types of noise
Sensor power supply
Fig. 5.3 Paths of noise These noises tend to gain the lower noise level as the noise frequency band is higher. Generally, the noise level is low enough not to be problematic in frequencies of 30MHz or higher. Consequently, though the noise does not affect a TV or FM radio used in the frequency of 30MHz or higher so much excluding some part, it affects the radios of the low frequency band (0.5 to 10MHz) such as an AM radio. As mentioned above, it is reasonable to consider the measures with attention to the noise frequency band.
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(1) Air-propagated noise (Paths 1) to 3)) This noise is generated in an inverter and radiated to the air. The paths of this noise can be classified into the three types shown in Fig. 5.4. 1) Radiated from inverter 2) Radiated from input cable 3) Radiated from motor connection cables
Power supply
(Motor frame earthling (grounding)) Earth (Ground)
Fig. 5.4 Air-propagated noise
(2) Electromagnetic induction noise (Paths 4) and 5)) This noise is generated and transmitted when power cables or signal cables of peripheral devices cross a magnetic field generated by the current that is input to or output from an inverter. (Refer to Fig. 5.5.) When the both cables are adjacent and parallel or the size of the loop created by each cable is large, the noise to be induced is also larger. (3) Electrostatic induction noise (Path 6)) This noise is generated and transmitted when an electric field generated by the inverter I/O cable is combined with signal cables through the electrostatic capacitances. (Refer to Fig. 5.6.) (4) Cable-propagated noise (Path 7)) This noise is a high-frequency noise that is generated inside the inverter and transmitted to peripheral devices through cables on the power supply side. (Refer to Fig. 5.7.)
External device
Motor IM
External device Signal source (Sensor, etc.)
Fig. 5.5 Electromagnetic induction noise
C (Electrostatic capacitance)
Signal source (Sensor, etc.)
Fig. 5.6 Electrostatic induction noise
External device
Signal source
Fig. 5.7 Cable-propagated noise
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To measure the magnitude of these noises, there are two methods, measuring the electric field intensity in the air or measuring the noise voltage in the power supply terminal part. (Refer to Fig. 5.8 Example of noise measurement.) The air-propagated noise is measured by the former, and the cable-propagated noise by the latter. Since there is no method to measure the electromagnetic induction noise and the electrostatic induction noise with accuracy, the noises are generally identified according to the data measured by the two mentioned above.
dB V/m Noise field intensity
Mains terminal interface voltage
dB V
Inverter : 200V system 3.7K Operation frequency : 30Hz Measuring distance : 15m
Mains terminal interface voltage
Noise field intensity
0 0.1 0.2 0.4 0.6 0.8 1 2 4 6 8 10 20 30 Frequency (MHz)
AM broadcast band
Fig. 5.8 Example of noise measurement
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5.3 Measures against Noise
5.3.1 Concept of the measures against noise
Although there are many noise propagation paths as described in Section 5.2, noise sources can broadly be classified into the following three types as shown in Fig. 5.2 and 5.3: 1) Propagation, induction or radiation from an input power supply cable 2) Induction or radiation from motor connection cables 3) Radiation from an inverter These noises tend to gain the lower noise level as the noise frequency band is higher. Generally, the noise level is not to be problematic in frequencies of 10MHz or higher. (Refer to Fig. 5.8.) Consequently, though the noise does not affect a TV or FM radio used in the frequency of 70MHz or higher, it affects the radios of the low frequency band such as an AM radio. As mentioned above, it is reasonable to consider the measures with attention to the noise frequency band. (1) Reducing noises transmitted to the power supply cable It is effective to install a filter between an inverter and the power supply cable. As a filter, the following types are available. How to use and the effect are described. 1) Radio noise filter FR-BIF (200V class), FR-BIF-H (400V class) This filter must be distinguished between for 200V and for 400V, but common for all capacities. As shown in Fig. 5.9, it is connected to the power input terminals of the inverter. If the connection cables between the filter and the inverter are long, this part becomes a noise radiation antenna and the effect cannot be exerted enough. Therefore, connect the filter connection cables including the ground cable directly to the terminals of the inverter and make the cables as short as possible. Also, if the distance from the ground terminal of the inverter to the earth is too long, the ground cable becomes an antenna and the enough effect may not be obtained. Therefore, the ground cable must be also made as short as possible. This filter has a larger effect at a few MHz or lower and is effective to reduce the noise to an AM radio. In addition, this filter has a built-in capacitor. Connecting it to the inverter output side causes damage, and therefore it is necessary to pay attention to make a correct connection.
Power supply R S T Inverter
FR-BIF Radio noise filter
Connect the connection cables directly to the input terminals of the inverter at the shortest distance.
Earth (Ground)
Fig. 5.9 Installation of radio noise filter FR-BIF
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2) Line noise filter FR-BSF01, FR-BLF Since this filter consists of only core, it can be used for all models regardless of the power supply voltage or capacity. As shown in Fig. 5.10, wind 3-phase wires in the same direction and insert them to the power input side of the inverter. The larger the winding number, the more effect can be obtained. Therefore, wind the wires four or more turns, as many as possible. However, if the wire is thick and cannot be winded four or more turns, prepare 2 or more filters and make the total winding number four or more turns. The two types are chosen and used depending on the wire size to be used. This filter has a larger effect at several 100 kHz or more. Also, this filter can be used on the inverter output side.
<< Inverter input side >>
NFB Power supply
As short as possible
<< Inverter output side >>
Inverter As short as Inverter U R S V
Number of windings must be within three turns (4T).
Line noise filter FR-BLF FR-BSF01
T Line noise filter FR-BLF FR-BSF01
Fig. 5.10 Installation of line noise filter FR-BSF01 and FR-BLF 3) Combination of FR-BIF(-H) and FR-BLF/FR-BSF01 As described above, FR-BIF is relatively effective to the noise of the low frequency, and FR-BLF to that of the high frequency. Therefore, combining the both filters brings a better result. As short as In this case, make a connection as possible NFB Inverter shown in Fig. 5.11.
Connection for good to know
Wind four turns with multiple line noise filters.
Power supply
R S Line noise filter FR-BLF FR-BSF01 GND T
Line noise filter
Point: Wind each three-phase cable in the same direction.
Connect the connection cables directly to the input terminals of the inverter at the shortest distance.
Earth (Ground)
Fig. 5.11 Combination of FR-BIF and FR-BLF/FR-BSF01
Good to know
For 55kW or less of the FREQROL-A700 and F700 series, functions equivalent to the line noise filter and radio noise filter on the input side are provided.
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4) Noise cutting transformer The noise cutting transformer is a transformer for which the magnetic and electrostatic coupling of the primary and secondary coils are extremely reduced, and it has a great reducing effect against not only the noise emission but also the noise entrance. (Refer to Table. 5.1.) Since there is no need to be earthed in principle, it is an ideal noise reducing method which exhibits the effect when a good grounding cannot be made or when a ground wire is lengthened. However, a transformer with a capacity necessary for the main circuit is required, three of single-phase transformer must be used for the three-phase power supply, and therefore it takes up space and is to be expensive. In addition, the internal impedance is large, and it is necessary to pay attention to the large voltage drop. Table. 5.1 Noise reducing example of noise cutting transformer
Measuring frequency [Hz] Reducing ratio -[dB] 5K 7.5K 10K 25K 50K 75K 100K 250K 500K 750K 1M 85 or less 74 or less 77 or less 72 or less 2.5M 54 or less 5M 45 or less 7.5M 10M 25M 50M 75M 100M 37 or less 32 or less 22 or less 28 or less 42 or less 46 or less
100 or less
(Note) Attenuation ratio = 20 log10
Voltage after attenuation Voltage before attenuation
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(2) Reducing noises radiated from cables between an inverter and a motor Installing the previously described FR-BLF or FR-BSF01 line noise filter to the output side of the inverter is a method to reduce the radiated noises. Generally, a metal pipe is used as shown in Fig. 5.12. Here, grounding the motor must be performed on the inverter side with one of the four-core cables, and as the thickness of a pipe, using a pipe of 2mm or more produce a better effect. Also, running the cable in a pit of the concrete instead of a metal pipe or placing the cable in a room surrounded by the concrete can produce a similar effect.
Metal case Metal pipe Power supply Inverter IM Earth (Ground)
Fig. 5.12 Piping process of motor connection cables (3) Reducing noises radiated from an inverter Generally, noises radiated from an inverter are relatively small and less problematic. However, when an inverter is installed close to the previously described devices easily affected by noises, it is required to place the inverter in a metal case and install a noise filter on the power supply side. Also, for the output side, connect a metal pipe to the case.
Noise filter Metal case Metal pipe Power supply Inverter IM Earth (Ground)
Fig. 5.13 Reducing noises radiated from an inverter
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5.3.2 Particular measure cases
(1) Corrective action and effect For each item of the measure example (refer to the next page.), the effect levels (estimated values) to be expected are as shown below. Refer to them for the priority determination when actually taking the measure. Table. 5.2 Effect of measures against noise
Noise propagation method Cable-propagated noise Electromagnetic Electrostatic Undesirable Power induction induction Power Motor path of Inverter supply noise noise cable earth supply radiation cable radiation (ground) cable radiation cable Air-propagated noise Definition of symbols : Substantially effective : Effective : Slightly effective -: No effective
Corrective action
Input side
Reduce the carrier frequency (Pr.72). (For FR-A series) Increase the input S/W filter constant (Pr.74). (For FR-A series) Install the radio noise filter FR-BIF(-H). Install the line noise filter FR-BSF01 or FR-BLF. Wire the power supply cable with a metal pipe or shield cable Install an insulated transformer or noise cutting transformer. Separate the power supply system. Install the line noise filter FR-BSF01 or FR-BLF. Wire the output cable with a metal pipe or shield cable Use 4-core cable for motor power cable and use one cable as earth (ground) cable. Use a twisted pair shielded cable for the sensor signal. Connect a shield to the common cable of the sensor signal. Do not ground the power supply unit for sensor directly to the enclosure, etc. Ground the power supply unit for sensor with a capacitor. Use a shielded cable for the signal input and connect a shield to the common (input terminal) SD. Use a twisted pair shielded cable for the speed input and connect a shield to the terminal 5. Insert a commercially available ferrite core to the speed input cable (on the output side of the external device). Reduce the impedance in the output circuit of the external device. Separate the external device from the inverter and power line by 30cm or more. Do not wire the cables in parallel with each other and do not bundle them. Install a closure plate. Suspend from the earth. Insert a commercially available ferrite core on the input side of the external device.
Output side
External device
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Measure example The following shows the methods in which an effect can be expected as the measures against noise of the inverter.
Commercial power supply line Caution: Even if the measures are taken for radio noise the desirable effect may not be obtained in the places with weak airwave such as mountain areas and inside of a building. V. Put in a place as far from the earth as possible. Radiated noise AM radio A. Decrease the carrier frequency. H. Install a filter (FR-BLF or FR-BSF01) (Set 0 (0.7kHz) in Pr.72.) on the inverter output side.
Receiving transformer Inverter power supply
E.Earth (Ground) a metal pipe (conduit pipe) or shielded cable to a machine at one point.
D.Install a filter (FR-BLF or FR-BSF01) on the inverter input side. F. Install an insulated transformer or noise cutting transformer. C. Install the filter FR-BIF on the inverter input side.
Motor I. Earth (Ground) a metal pipe (conduit pipe) or shielded cable to the enclosure. J. Use 4-core cable for motor power cable and use one cable as earth (ground) cable.
B. Increase the parameter Pr.74 (input filter constant) setting value of the FR-A inverter. (However, note that the response level will be slower.)
O. Connect a shield to SD with a shielded cable. G. Separate the power supply system. PLC or microcomputer board Q. Insert a commercially available ferrite core.
Control power supply
2 400/200V P. Connect a shield to the terminal 5 with a twisted pair shielded cable. S. Separate the inverter and power line from sensor circuit by 30cm or more. (at least 10cm) 0 to 5VDC 5 R. Reduce the impedance of the output circuit. Chassis of the enclosure or machine
W. Insert a commercially available ferrite core.
DC power supply for sensor N. Earth (Ground) to the enclosure via the capacitor of N.0.1 to 0.01 F.
K. Use a twisted pair shielded cable. Sensor
L. Connect a shield to the common cable of the signal without earthling.
M. Stop earthing (grounding) directly to the enclosure.
Use a sensor with high noise capacity.
Fig. 5.15 Examples of measures against noise of the inverter
Wiring method in the enclosure U. Closure plate
Inverter T. Put as much distance as possible between them and do not wire the cablesin parallel with each other and do not bundle them. If unavoidable, cross them. Noise filter S. 30cm or more (at least 10cm)
Terminal block
Terminal block
Power supply Motor Control power supply
Connect. Limit switch sensor
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5.3.3 Noise filter
(1) Outline drawing of the noise filter (Unit: mm) (a) FR-BIF and FR-BIF-H
Red White Blue Green
29 44
The same outline is applied for FR-BIF (200V class) and FR-BIF-H (400V class). (b) FR-BLF and FR-BSF01 FR-BLF
31.5 22.5
25 hole
2- 7
130 85
4 7
(65) (33)
160 180
95 110
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(2) Noise reducing effect examples (a) FR-BIF and FR-BIF
Carrier frequency: 14.5kHz 120 a Mains terminal interface voltage (dB) 100 Measurement conditions 200V system 3.7K a. No measure against noise b. Install the FR-BLF (4T) on the input side. c. Install the FR-BIF and FR-BLT (4T) on the input side.
b c
20 Mains terminal interface voltage (average value) 0 0.1 0.2 0.3 0.5 0.7 1 2 3 5 7 10 20 30
Noise frequency (MHz) Carrier frequency: 2kHz 120 Measurement conditions 200V system 3.7K a. No measure against noise b. Install the FR-BLF (4T) on the input side. c. Install the FR-BIF and FR-BLT (4T) on the input side. a 80 b 60 c
Mains terminal interface voltage (dB)
20 Mains terminal interface voltage (average value) 0 0.1 0.2 0.3 0.5 0.7 2 3 5 1 Noise frequency (MHz) 7 10 20 30
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5.4 Leakage Current
In I/O cables and motors of an inverter, the electrostatic capacitances exist. The leakage current flows through them. The amount of the leakage current differs depending on the electrostatic capacitances, carrier frequency, etc. Accordingly, the low-noise type inverters generate the larger leakage current, and therefore take measures in the following methods.
5.4.1 Leakage current between grounds
The leak current may flow into not only the inverter's own system but also other system through the earth cable. The leakage breaker or leakage relay may operate unnecessarily due to this leakage current. (1) Measures
● Decrease the carrier frequency (Pr. 72) of the
inverter. Note that doing so causes a louder motor noise.
Power supply
NV1 Leakage breaker NV2 Leakage breaker
Inverter Motor
● For leakage breakers for the inverter's own line
and other line, select the ones designed for harmonic and surge suppression to take measures with low noise (with the carrier frequency kept high).
Fig. 5.17 Undesirable current path of leakage current * Refer to Section 7.5 for the selecting method of a leakage breaker.
(2) Data example of leakage current between grounds
Note that the leakage current increases when wiring length is long. By decreasing the carrier frequency of the inverter, the leakage current can be reduced. The leak current increases as the motor capacity becomes larger. The leakage current of 400V system becomes larger than that of 200V system.
1000 400
Leakage current (mA)
Leakage current (mA)
Conditions Motor SF-J3.7kW 4P Output frequency 30Hz
Carrier frequency 14.5Hz 10kHz
700 500 300 200 100 70 50 400V system
200V system
200 2kHz 1kHz
Conditions Wiring length : 20m Carrier frequency : 14.5kHz Output frequency : 14.5kHz
100 Wiring length on
the output side (m)
1.5 2.2 3.7 5.5 7.5 11 15 22 30374555 18.5 Motor capacity (kW)
Fig. 5.18 Difference of the leakage current between grounds by the carrier frequency and the wiring length
Fig. 5.19 Difference of the leak current between grounds by the motor capacity
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5.4.2 Leakage current between cables
The external thermal relay may operate unnecessarily due to the harmonics of the leakage current flowing in electrostatic capacitances between the inverter output cables. When the wiring length is long (50m or more) for the 400V series small-capacity model (especially 7.5kW or less), the external thermal relay is likely to operate unnecessarily because the ratio of the leakage current to the rated motor current increases. Table 5.3 Data example of leakage current
Power supply
Thermal relay Inverter
Electrostatic capacitance between cables
between cables (200V series)
Fig. 5.20 Paths of leakage current between cables
Motor Leakage current (mA) Rated motor capacity current Wiring length Wiring length (kW) ( A) 50m 100m 0.4 1.8 310 500 0.75 3.2 340 530 1.5 5.8 370 560 2.2 8.1 400 590 3.7 12.8 440 630 5.5 19.4 490 680 7.5 25.6 535 725 2 ●Motor: SF-J 4P ●Used cable: 2mm 4-core ●Carrier frequency: 14.5kHz Cab-tire cable For the 400V series, the leakage current is approximately 2 times.
(1) Measures
● Use the electronic thermal of the inverter. ● Decrease the carrier frequency. Note that doing so causes a louder motor noise.
To ensure that the motor is protected against leakage current between cables, it is recommended to use a temperature sensor to directly detect motor temperature.
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5.5 Earth (Ground)
Generally, an electrical apparatus has an earth (ground) terminal, which must be connected to the ground before use. An electrical circuit is usually insulated by an insulating material and encased. However, it is impossible to manufacture an insulating material that can shut off a leakage current completely, and actually, a slight current flow into the case. The purpose of earthing (grounding) the case of an electrical apparatus is to prevent operator from getting an electric shock from this leakage current when touching it. To avoid the influence of external noises, this earthing (grounding) is important to audio equipment, sensors, computers and other machines that handle low-level signals or operate very fast. As above, there are two types of the earthing (grounding), which have completely different characters. Applying them together for earthing (grounding) causes troubles as a matter of course. Therefore, it is necessary to differentiate between a dirty earthing (grounding) for electric shock prevention and a clean earthing (grounding) for noise prevention. In addition, when the inverter is used, the output voltage becomes not a sine wave but a steep waveform as shown in Fig. 2.17 of Chapter 2, and therefore the charging/discharging current to the electrostatic capacitances existing in the insulation part flows as leakage current. Moreover, the same charging/discharging leakage current flows to the motor to which the output voltage of this inverter is applied, and it becomes a larger current value with more high frequency components compared to that in the operation with the commercial power supply as shown in Fig. 5.22. The higher the inverter carrier frequency is, the stronger this tendency develops.
5.5.1 Earthing (grounding) methods and earthing (grounding) work
As described previously, earthing (grounding) is roughly classified into an electrical shock prevention type and a noise-affected malfunction prevention type. Therefore, these two types should be discriminated clearly, and the following work must be done to prevent the leakage current having the high frequency components from entering the malfunction prevention type earthing (grounding): (a) Where possible, use independent earthing (grounding) for the inverter. (Refer to Fig. 5.21.) If independent earthing (grounding) (same figure (a)) is impossible, use joint earthing (grounding) (same figure (b)) where the inverter is connected with the other equipment at an earthing (grounding) point. Joint earthing (grounding) as in (c) of the same figure must be avoided as the inverter is connected with the other equipment by a common earth (ground) cable. Especially, joint earthing (grounding) with a high-power equipment such as a motor and transformer must be avoided. Also a leakage current including many high frequency components flows in the earth (ground) cables of the inverter and inverter-driven motor. Therefore, they must use the independent earthing (grounding) method and be separated from the earthing (grounding) of equipment sensitive to the aforementioned noises.
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In a tall building, it will be a good policy to use the noise malfunction prevention type earthing (grounding) with steel frames and carry out electric shock prevention type earthing (grounding) in the independent earthing (grounding) method.
Inverter Other model Inverter Other model Inverter Other model
Class D grounding
Class D grounding
(a) Dedicated earthing
(b) Common earthing
(c) Common earthing
Fig. 5.21 Earthing (grounding) methods (b) Use Class D grounding (grounding resistance 100Ω or less) for the 200V class inverter and Class C grounding (grounding resistance 10Ω or less) for the 400V class on the earthing (grounding) work. (c) Use the thickest possible earth (ground) cable. The earth (ground) cable should be of not less than the size indicated in the instruction manual. (d) An earthing (grounding) point should be as close to the inverter as possible, and make an earth cable as short as possible. (e) Run the earth (ground) cable as far away as possible from the I/O wiring of equipment sensitive to noises and run them in parallel in the minimum distance. (f) Use one wire in a 4-core cable with the earth (ground) terminal of the motor and earth (ground) it on the inverter side. If the earthing (grounding) of the inverter and the motor driven with the inverter is connected together with the earthing (grounding) of an audio, sensor, computer, etc., the generated leakage current becomes a noise source and makes a bad effect. To solve this problem, earthing (grounding) work must be performed using separately a dirty earthing (grounding) of an inverter, etc. and a clean earthing (grounding) of an audio, sensor computer, etc.
Power supply
Fig. 5.22 Example of motor earth cable current when driven with the inverter (Inverter: 200V system 0.75K, Motor: SF-JR 0.75kW 4P)
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This chapter describes the reliability and life of inverters according to the installation environment and operating conditions as well as the precautions for them. This chapter also describes the circuit designs, precautions for wiring and operation procedures to use inverters.
6.1 Environment and Installation Conditions
6.1.1 Reliability of the inverter and temperature
The life of an inverter is influenced by the ambient temperature. When an inverter is installed in a high ambient temperature or poorly installed for a wrong selection of the installation place, unexpected troubles such as a failure or damage may occur. Those troubles are caused by the following factors.
Heat stagnation in the panel Heat dissipation of the enclosure is insufficient. (e.g. The size is small; ventilation is not enough.)
High ambient temperature
Ventilation slits of the inverter are narrow. The inverter is installed in an improper place. An exothermic body is near the inverter.
The inverters mounting orientation is improper.
High internal temperature of an inverter
The space over the inverter is not enough. The inverter fan is faulty.
6.1.2 Ambient temperature
The ambient temperature of an inverter is a temperature of the close periphery of an installed inverter. 1) Measure the temperature at the positions indicated in Fig. 6.1. 2) The permissible temperature between -10 +50 . (Too high or too low temperature may cause troubles.) 3) "In-panel temperature +50 , or less" means that the ambient temperature of the panel must be 40 less. or Fig. 6.1 Measurement of ambient temperature
5cm 5cm 5cm
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Good to know for checking an inverter Life
smoothing decreases to half if the ambient temperature increases by 10 doubles if decreases by 10 accordance with the Arrhenius' law. The lives of the other parts also highly depend on
Initial failure period Temperature Life " Arrhenius law "
The life of an inverter's electrolytic capacitor for (18°F) (and (18°F)) in
the temperature.
Failure rate and temperature
An inverter consists of many electronic parts such as semiconductor devices. The failure rate of these parts is closely related to the ambient temperature. Using them in the temperature as low as possible decreases the failure rate.
Failure rate
Random failure period
Wear-out failure period
Ambient temperature 50 45 40 Time (year)
6.1.3 Heat generation of the inverter
The heat amount generated by an inverter varies depending on the inverter's capacity and the motor load factor. In addition, the optional parts enclosed with an inverter such as a power factor improving reactor or brake unit (including a resistor) generate the relatively large heat amount. This should be taken into consideration when an enclosure is designed. Table 6.1 lists the generated heat amount. Externally installing the semiconductor heatsink and built-in break resistor using a heatsink outside attachment can radiate approximately 70% of the heat amount generated by the inverter to the outside of the enclosure. Refer to Fig. 6.2 for how to use the heatsink outside attachment.
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Table 6.1 Heat amount generated from the inverter and power factor improving reactor Heat amount Heat amount generated from power factor generated from improving reactors (W) Motor FREQROL-A700 capacity (W) (kW) 200V 400V FR-HEL FR-HAL 200V 400V 200V 400V 16 6 10 6 50 50 0.4 23 14 7 7 70 65 0.75 30 20 8 8 110 75 1.5 43 24 11 11 140 100 2.2 46 33 13 13 190 150 3.7 52 40 17 17 200 5.5 260 52 46 19 19 250 7.5 360 60 60 23 23 300 11 520 60 75 26 26 400 15 670 76 74 29 29 550 18.5 770 74 82 34 34 940 650 22 91 97 38 38 1050 800 30 97 120 47 47 1270 1100 37 140 140 47 47 1610 1300 45 150 140 52 52 1550 1880 55 180 170 130 130 1900 2530 75 130 130 3110 2400 90 200 280 140 160 2500 110 140 3000 132 170 4000 160 400 230 4200 185 240 5000 220 270 5500 250 490 300 6500 280 360 7000 315 530 360 8000 355 450 9000 400 450 10500 450 470 11500 500 1080 500 560 (Note) The heat amount generated by built-in brake resistors of 7.5K or less is not included.
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6.1.4 Interference of heat in the enclosure and ventilation
The inverter and ventilation fan placement is another point to be noted when they are installed in an enclosure. When multiple inverters are installed in an enclosure or a ventilation fan is installed, the ambient temperature of the inverters may rise and ventilation effect may be reduced depending on the installation position.
Cooling wind Cooling fan Inverter Heat sink Enclosure Inside enclosure Installation fitting FR-A7CN (Option)
Fig. 6.2 How to use the heatsink outside attachment
Inverter Inverter
Air guide
Fig. 6.3 Installation of multiple inverters
Fig. 6.4 Position of a ventilation fun
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6.1.5 Placement of electrical-discharge resistor
When a BU type brake unit or externally-installed high-duty brake resistor (FR-ABR type) is used, sufficient measures against heat generated from resistors must be taken. Consider a resistor to be a heater for cooling. It is recommended to install electrical-discharge resistors outside the enclosure.
Install exoergic covers Use a cooling fan to prevent burn injuries. as required.
Caution: The surface of the electrical-discharge resistors sometimes becomes as high as 300 . Caution must be used for the material of the installing surface and the layout for the use of multiple resistors.
Electrical-discharge resistor
Electrical-discharge resistor
Fig. 6.5 Installation method of the resistor
7cm or more
Fig 6.6 Layout of the resistors
6.1.6 Inverter mounting orientation
When an inverter is not mounted with a proper orientation, the inverter's heat dissipation extremely deteriorates. (The printed board of the control circuit is not cooled by a cooling fan.)
Vertical installation
Lateral installation
Horizontal installation
Fig. 6.7 Inverter mounting orientation
6.1.7 Standard specifications of installation environment (FREQROL-A700 series 200V class)
Item Ambient temperature Ambient humidity Ambience Maximum altitude Vibration AC voltage/frequency Permissible voltage fluctuation Permissible frequency fluctuation Description -10 to +50 (non-freezing) Relative humidity: 90%RH or less (non-condensing) Indoors: free from corrosive gas, explosive gas and flammable gas. Free from dust, dirt and oil mist. 1,000m or less above sea level 5.9m/s2 or less (conforming to JIS C60068-2-6) Three-phase, 200V to 220V 50Hz, 200 to 240V 60Hz 170 to 242V 50Hz, 170 to 264V 60Hz 5%
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Temperature (1) Measures against high temperature (a) Use a forced ventilation system or similar cooling system. (Refer to Section 6.1.4.) (b) Install the panel in an air-conditioned electrical chamber. (c) Block direct sunlight. (d) Provide a shield or similar plate to avoid direct exposure to the radiated heat and wind of a heat source. (e) Ventilate the area around the panel well. (2) Measures against low temperature (a) Provide a space heater in the panel. (b) Keep the inverter power on. (Keep the start signal of the inverter off.) (3) Sudden temperature changes (a) Select an installation place where temperature does not change suddenly. (b) Avoid installing the inverter near the air outlet of an air conditioner. (c) If temperature changes are caused by opening/closing of a door, install the inverter away from the door. Humidity Normally operate the inverter within the 45 to 90% range of the ambient humidity. Too high humidity will pose problems of reduced insulation and metal corrosion. On the other hand, too low humidity may produce a spatial electrical breakdown. The insulation distance specified in JEM1103 "Control Equipment Insulator" is defined as humidity 45 to 85%. (1) Measures against high humidity (a) Make the panel enclosed, and provide it with a hygroscopic agent. (b) Take dry air into the panel from outside. (c) Provide a space heater in the panel. (2) Measures against low humidity What is important in fitting or inspection of the unit in this status is to discharge your body (static electricity) beforehand and keep your body from contact with the parts and patterns, besides blowing air of proper humidity into the panel from outside. (3) Measures against condensation Condensation may occur if frequent operation stops change the in-panel temperature suddenly or if the outside-air temperature changes suddenly. Condensation causes such faults as reduced insulation and corrosion. (a) Take the measures against high humidity in (1). (b) Keep the inverter power on. (Keep the start signal of the inverter off.)
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6.1.8 Precautions for encasing the inverter in an enclosure
Refer to Fig. 6.8 for precautions for encasing the inverter in an enclosure.
Leave enough clearance between the installed devices generating a large amount of heat. 1cm or more for 3.7k or less 5cm or more for 5.5k or less 10cm or more for 7.5k or more Install a ventilation fan at the best position to keep the in-panel and ambient temperature low. Avoid deficient capacity.
Install other devices at the position where the cooling wind is not blocked. Avoid the installation of the devices easily affected by heat. 10cm or more for 55k or less 20cm or more for 75k or more
Install with a proper orientation.
Install resistors with a large amount of generated heat such as an electrical-discharge resistor outside the panel.
Leave enough clearances above and under the inverter to ensure adequate ventilation. 10cm or more for 55k or less 20cm or more for 75k or more
Wire the control signal lines away from the main circuit (power circuit) without bundling them together.
Air filter Clean and inspect the filter periodically to prevent clogging.
Power factor improving reactor
Fig. 6.8 Precautions for encasing the inverter in an enclosure
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Dust, dirt, oil mist Dust and dirt will cause such faults as connection errors of contacts, reduced insulation resulting from moisture absorption of deposits, reduced cooling effects and in-panel temperature rise by filter clogging. In the atmosphere where conductive powder floats, dust and dirt will cause such faults as malfunction, deteriorated insulation and short circuit in a short time. Since oil mist will cause similar conditions, it is necessary to take adequate measures. Corrective action (a) Place in a totally enclosed panel. Take measures if the in-panel temperature rises. (b) Purge air. Pump clean air from outside to make the in-panel pressure higher than the outside-air pressure. Corrosive gas, salt damage If the inverter is exposed to corrosive gas or to salt near a beach, the printed board patterns and parts will corrode and the relays and switches will result in poor contact. In such places, take the measures given in (a) and (b). Explosive, flammable gases As the inverter is non-explosion proof, it must be contained in an explosion proof enclosure. In places where explosion may be caused by explosive gas, dust or dirt, an enclosure cannot be used unless it structurally complies with the guidelines and has passed the specified tests. This makes the enclosure itself expensive (including the test charges). The best way is to avoid installation in such places and install the inverter in a non-hazardous place. Highland Use the inverter at the altitude of within 1000m. If it is used at a higher place, it is likely that thin air will reduce the cooling effect and low air pressure will deteriorate dielectric strength. Vibration, impact The vibration resistance of the inverter is up to 5.9m/s2* at 10 to 55Hz frequency as specified in JIS C60068-2-6. Vibration or impact, if less than the specified value, applied for a long time, may make the mechanism loose or cause poor contact to the connectors. *2.9m/s2 according to the capacity Especially when impact is imposed repeatedly, caution must be taken as the part pins are likely to break. Corrective action (a) Provide the panel with rubber vibration isolators. (b) Strengthen the structure to prevent the panel from resonance. (c) Install the panel away from sources of vibration.
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6.1.9 When driving an explosion-proof motor with the inverter
When an explosion-proof motor is used with the inverter for drive, they must pass the specified exam. Please note the following for installation. (1) The existing commercial power-driven pressure-resistant explosion-proof motor or
increased-safety explosion-proof motor cannot be driven by the inverter. Acquiring TIIS Certification of Conformity is necessary for the combination of a motor and inverter to be used. The certification is managed by Technology Institution of Industrial Safety. A pressure-resistant explosion-proof motor which has acquired TIIS Certification of Conformity beforehand in combination with an inverter drive can be used by combining another inverter. However, the inverter must be the same model (up to the model's capacity) used when the certification has been approved and the operation is limited to the range under the certified conditions. Mitsubishi Electric offers pressure-resistant explosion-proof motors dedicated to an inverter drive and inverters for them. Refer to a catalog for details. (2) When the rating to be used is out of the certified range or the model which has not passed TIIS Certification of Conformity needs to be used, a new certification must be acquired for it. (3) Refer to an instruction manual of the inverter when using options. (4) Using an increased-safety explosion-proof motor with an inverter is not economical for the strict restrictions against the operation conditions (loss reduction, cooling effect improvement, etc.) and also for the costs to take the test. Using a pressure-resistant explosion-proof motor which has passed TIIS Certification of Conformity is recommended. (5) The inverter is a non-explosion proof structure. Always install it in a non-hazardous place.
Good to know for checking an inverter
When an inverter-drive explosion-proof motor used for constant torque is needed, using one (which has passed TIIS Certification of Conformity) with one or two ranks higher capacity is economical.
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6.2 Wiring of Inverter
6.2.1 Terminal connection diagram
Catalogs describe the connection condition of each terminal for the inverter drive. The specifications of these terminals and precautions for use are given below using FREQROL-A700 series as an example.
Fully check the current and voltage before connection. Phase sequence needs not to be matched. NFB Power supply R S T The voltage for the control circuit is supplied from the R and S phases. Jumper R1 S1 PU connector
USB connector U V W
This side is a group of input signal terminals.
This side is a group of output signal terminals.
Rotation direction changes if the motor phase sequence is changed.
Inverter Motor IM
Earth (Ground) Power factor improving DC reactor FR-HEL
24VDC power supply and external transistor common PC Control input signals (no voltage input allowed)
R High-duty brake resistor FR-ABR
P indicates plus and N minus. (DC)
If both are turned on at the same time, the inverter will come to a stop.
Forward rotation start Reverse rotation start Start self-holding selection
High Multi-speed speed selection Middle (Maximum 7 speeds) speed Low speed
STF STR STOP RH RM RL JOG RT MRS RES AU CS SD common
Contact input
A1 B1 C1 A2 B2 C2 Alarm output (Contact output) Relay output
Combination of turning on/off three terminals allows the operation in a maximum of seven speeds.
Dry contact output Make sure contact specifications.
Jog mode
Second acceleration/ deceleration time selection
Output stop Reset Current input selection
Selection of automatic restart after instantaneous power failure
RUN Running SU Up to frequency IPF Instantaneous power failure OL Overload FU Frequency detection SE Open collector output common
Open collector outputs. Power supply (24VDC or less) is required. Note the polarity.
Do not short terminals 10(10E)-5.
Frequency setting signals (Analog)
10E( 10V) FM 10( 5V) 0 to 5V Initial value 2 0 to 10V switching 4-20mA 5 Analog common 1 DC0 to 10V RS485 4-20mA Initial value terminal 4 0-5V switching 0-10V
DC0 to 5V/ Switching
Calibration resistor Indicator (Frequency meter, etc.) 1/2W10k
Not required if the parameter unit is used for setting.
Frequency setting potentiometer 1/2W 1k Use shielded cables for these terminals and make the cable length as short as possible (30m or less at a maximum, excluding the terminal 4).
Moving-coil type 1mA full-scale
) Analog signal output )
(0 to 10VDC)
Auxiliary input
Current input
Securely perform earthing (grounding) with an appropriate cable size.
Earth (Ground)
RS485 communication
Main circuit terminal Control circuit Input terminal Control circuit output terminal
Do not earth (ground) common terminals (including SD).
Fig. 6.9 Terminal connection diagram
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6.2.2 Wiring of the main circuit
The main circuit is the power circuit (high voltage in lines). Incorrect wirings may damage the inverter and also jeopardize the operators. The following shows the points that easily cause miswiring.
Do not apply a voltage higher than the inverter permissible voltage.
Do not use this magnetic contactor (MC) for frequent starting/ stopping of the inverter. Basic sequence example without MC
NFB Power supply 200V power supply R S T NFB F Start Stop MC CR1 CR2 CR1 CR2 STF(STR) SD
S T Inverter
Application of power to the terminals U, V and W will damage the inverter.
If interlocks are not provided electrically and mechanically to prevent MCC and MCF from being turned on at the same time, undesirable currents occur (the power is applied to the terminals U, V and W) (including an arc short circuit).
Confirm that the phase sequence of the commercial power supply is R, S and T.
IM Motor Do not connect the terminal (2) of the frequency setting potentiometer to the inverter terminals 10 or 5. (3) (2) (1) 10 2 5 (1) (3) 10 (2) 2 5
A long wiring distance causes the decreased motor torque for a cable voltage drop at the low-frequency operation. Perform wiring with a cable thick enough. When the cable cannot be directly connected to the inverter terminal for the thickness, use a junction terminal block.
Example of false wiring
Fig. 6.10 Main circuit wiring
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6.2.3 Wiring of the control circuit
The following table lists the I/O terminal types and common terminals equipped with the inverter. Terminal Input terminals Type Contact (or open collector) Analog Contact Output terminals Open collector Pulse train Analog Terminal example Start signal (STF, STR) Select signal (RH, RM, RL, AU, etc.) Frequency setting signal (2, 1, 4, etc.) Alarm output (A, B) Running signal (RUN, SU, OL, IPF, FU) For indicator (frequency meter (FM)) For analog signal output (AM) Common terminal SD or PC (Power common +) 5 C SE SD 5
(1) Connection to input terminals 1) Contact or open collector input terminal (Isolated from the inverter internal circuit) Each terminal operates for its function by causing a short circuit to the common terminal SD. The carry current for the input signals is micro-current (4 to 6mADC). Therefore, switches or relays for micro-current (twin contacts, etc.) must be used to prevent contact faults.
Note the contact error. RA (STF) Micro-current SD (Common) SD SD 24 VDC (STF) PLC, etc. (STF) PC PLC, etc. (Transistor output) STF
Contact input (Switch)
Contact input (Relay)
Open collector
Open collector (External power supply type)
Fig. 6.11 Connection for input signals 2) Analog input terminals (Non-isolated from the inverter internal circuit) Perform the wiring fully away from the 200V (400V) power circuit lines without bundling them together. The shielded cable should be used to avoid the influence of external noises.
External noises Do not bundle. Power supply Induction noise R S T 10 2 5 Shielded cable
Fig. 6.12 Connection example of frequency setting input terminals
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3) Proper connection of frequency setting potentiometer Improper connection of the frequency setting potentiometer terminals without referring to the terminal symbols will affect the operation of the inverter. The resistance value is an important factor to select a frequency setting potentiometer. <Specification> Wire-wound, 2W, 1kΩ, B characteristic
C characteristic B characteristic
2 3
Resistance value
A characteristic
10 2
Motor speed <Correct connection>
Fig. 6.13 Connection of frequency setting potentiometer (2) Connection to output terminals
Open collector output terminal
As a noise reduction technique, it is recommended to use a flywheel diode or capacitor. Note the polarity.
Relay RA 24VDC
Prepare the DC current with the ripple voltage of 10% or less. Always make sure before wiring that polarity is correct.
SE The permissible current is 0.1A.
Pulse train output terminal
Pulse train FM Calibration resistor R 10k 1/2W 1mA Frequency meter
Analog signal output (0 to 10VDC)
10V voltmeter AM
SD (Common)
5 Shielded cable The pulse train output outputs the voltage in proportion to the output frequency (average value). The output status can be known by using a tester (10VDC range). Tester
Fig 6.14 Connection of output signal terminals
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6.2.4 Wiring length of I/O cables
The restriction varies according to each I/O terminal. Especially for control signals, the input part is isolated by photocoupler for improving noise resistance. However, the isolation measure is not taken for the analog input. Therefore, the special caution must be used for the wiring for the frequency setting signal by taking a measure such as making the cable length as short as possible to protect the signal from the external noise. The indication of the permissible cable length for each signal and the measures taken when the length is exceeded are shown in Fig. 6.15.
Power supply cable on the input side
Motor cable on the output side
Determine the cable size not to cause a large voltage drop. (Note that the output voltage is low according to the V/Fpatternat a low frequency.) The overall length must be determined within the range given in the instruction manual in consideration of a charging current caused by the stray capacitances of the cable.
When a voltage drop occurs, the maximum output voltage does not exceed this voltage.
NFB R Power supply S T Start Contact input signal When the cable length is long, installing a relay near the inverter is recommended. STF (STR), etc. SD 30m or less RES SD Shielded cable 10
Frequency setting potentiometer
U Inverter V
Motor IM
Reset 30m or less Twisted cable or shielded cable
2 5
FM SD AM 5 30m or less
Frequency meter (Digital)
Analog input signal When the operation is performed remotely, installing a motorized speed setter near the inverter and using the 4 to 20mA signal are recommended. 30m or less
50m or less
Fig. 6.15 Wiring length of I/O cables
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6.2.5 Wiring for the BU type brake unit
(1) Connect a BU type brake resistor paired with a resistor to the inverter terminal P-N.
Never connect the brake unit terminals P and N inversely. Always match the terminal symbols P-N to that of the inverter. Incorrect connection may damage the inverter.
NFB MC R S T PR Inverter
(Note 2)
T (Note 1) MC
OFF Fit a jumper.
Electrical-discharge resistor
Remove the jumper.
Brake unit (BU type)
(Note 1) When the power supply is 400V class, install a step-down transformer. (Note 2) For capacity 7.5K or less, remove the jumper across terminals PR-PX.
Fig. 6.16 Wiring method for the brake unit (2) The wiring length between the inverter and the BU type brake unit or between the BU type brake unit and the electrical-discharging resistor is restricted to be a maximum of 5m. When the wiring length is more than 2m and less than 5m, a twisted cable must be used for wiring.
FREQROL inverter P N
P Brake unit N PR
2m or less
2m or less
FREQROL inverter P N
Twisted P Brake unit N 2 to 5m PR
Twisted R R R
2 to 5m
Fig. 6.17 Wiring length for the brake unit
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6.2.6 Wiring for the FR-BU type brake unit
(1) Connect an FR-BU type brake unit paired with an FR-BR type resistor unit to the inverter terminals P-N.
Never connect the brake unit terminals P and N inversely. Always match the terminal symbols P-N to that of the inverter. Incorrect connection may damage the inverter. For safety, prepare a circuit where an alarm contact of the brake unit or resistor unit shuts off the inverter primary side magnetic contactor.
Moulded case circuit breaker
T(Note 2)
MC R S T (Note 1) U V W PR P/+ HA N/- HB HC Brake unit FR-BU PR P TH1 THS TH2 Resistor unit FR-BR ON OFF MC
(Note 1) Be sure to remove a jumper across terminals PR-PX when using the FR-BU with the inverterb of 7.5kW or less. (Note 2) When the power supply is 400V class, install a control transformer.
Fig. 6.18 Wiring method for the brake unit (2) There is a restriction for a cable length between the inverter and the FR-BU type brake unit or between the FR-BU type brake unit and the FR-BR type resistor unit. When the wiring length is more than 5m and less than10m, a twisted cable must be used for wiring.
Inverter P N Resistor unit Brake unit P P N PR P PR
5m or less
5m or less
Twisted PR
10m or less
10m or less
Fig. 6.19 Wiring length for the brake unit
*Refer to the FREQROL-A700 catalog for the MT-BU5 (75k or more) type brake unit.
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Resistor unit
Brake unit
6.2.7 Wiring for the high-duty brake resistor (FR-ABR)
The built-in brake resistor is connected across terminals P and PR. Remove the jumper across terminals PR-PX when the built-in brake resistor does not have enough thermal capability for high-duty operation. Then, fit the high-duty brake resistor to the terminals P and PR. (Note) Do not connect resistors other than the high-duty brake resistor. Using the following sequences is recommended to prevent the overheat and burnout of the brake resistor when the regenerative brake resistor is damaged.
<Example 1>
*1 Since the 11K or more inverter is not provided with the PX terminal, a jumper need not be removed. *2 Refer to the table below for the type number of each capacity of thermal relay and the diagram below. (When using a 11k or more brake resistor, always install the thermal relay.)
Power supply voltage
High-duty brake resistor FR-ABR-0.4K FR-ABR-0.75K FR-ABR-2.2K FR-ABR-3.7K FR-ABR-5.5K FR-ABR-7.5K FR-ABR-11K FR-ABR-15K FR-ABR-22K FR-ABR-H0.4K FR-ABR-H0.75K FR-ABR-H2.2K FR-ABR-H3.7K FR-ABR-H5.5K FR-ABR-H7.5K FR-ABR-H11K FR-ABR-H15K
Thermal relay type (Mitsubishi products) TH-N20CXHZ-0.7A TH-N20CXHZ-1.3A TH-N20CXHZ-2.1A TH-N20CXHZ-3.6A TH-N20CXHZ-5A TH-N20CXHZ-6.6A TH-N20CXHZ-11A TH-N20CXHZ-11A TH-N60-22A TH-N20CXHZ-0.24A TH-N20CXHZ-0.35A TH-N20CXHZ-0.9A TH-N20CXHZ-1.3A TH-N20CXHZ-2.1A TH-N20CXHZ-2.5A TH-N20CXHZ-6.6A TH-N20CXHZ-6.6A
Contact rating
110VAC 5A, 220VAC 2A (AC11 class) 110VAC 0.5A, 220VDC 0.25A (DC11 class)
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7.1 Types of Peripheral Devices and Points to Understand
How is the power supply capacity (transformer capacity) determined? Transformer TR 1 Why does an ELB trip easily occur after the inverter is added to the existing facilities? 2 Is the rated sensitivity current selected? Leakage current breaker Moulded case circuit breaker ELB Power factor correction capacitor 1 Define the reason why a power factor is improved! 2 What effects does it have? MCCB 1 How are the use applications Magnetic contactor MC Power factor improving reactor FR-HEL Line noise filter FR-BLF Radio noise filter FR-BIF for the line noise filter and the radio noise filter separated? 2 What effects do they have when installed on the output side? Does it have effects from the inverter?
Is the rated current selected?
1 What is the purpose to install the MC? 2 How is the capacity selected? 3 What are precautions on use?
1 Define the reason why a power factor is improved! 2 What effects does it have?
Power factor improving reactor FR-HEL
Inverter Why is the cable size larger than a commercial one? Output side cable
Frequency setting potentiometer VR
1 Are there restrictions for a
Frequency meter
Line noise filter FR-BLF MC Surge suppression filter
resistance value, etc? 2 How many inverters can one volume operate?
1 When and where is the MC installed on the output side? 2 What are precautions on use?
Magnetic contactor
1 How long is the maximum distance from the inverter? 2 Can multiple inverters be connected? 3 Is the digital display available?
1 Can a commercially available electronic thermal be used? 2 How is a thermal relay selected? Thermal relay OCR
1 When and where is the surge Motor IM suppression filter used?
Fig. 7.1 Peripheral devices
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7.2 Inverter Options
To use a general-purpose inverter more effectively, various options can be used for improving the characteristics such as an applied operation. Table 7.1 Types and applied examples of FREQROL-A700 series inverter options Classification Requested specifications Examples of applied options ▪ To set the operation frequency with a digital FR-A7AX (16-bit digital input) switch ▪ To set the operation frequency with a PLC FR-A7NC (CC-Link) ▪ To monitor the output frequency, output voltage and output current simultaneously ▪ To perform the remote operation of the inverter ▪ To perform the automatic operation of the inverter ▪ To perform the inverter operation with a PC or PLC ▪ To change a parameter remotely ▪ To start the inverter easily FR-Configurator(FR-SW2-SETUP-WJ) ▪ To set a parameter with a PC easily (Inverter setup software) ▪ To set a parameter with direct input FR-PU07 ▪ The parameter unit displayed in English is (Parameter unit) required. ▪ To install the inverter in an enclosure and FR-CB201,03,05 mount the parameter unit to a door (Connection cable) ▪ To operate near the inverter ▪ To drive the AC relay and a contactor with FR-A7AR (Relay output) Output signal the inverter output signal ▪ The power supply capacity must be larger if FR-HAL, FR-HEL※ Power factor the inverter power factor is low. (Power factor improving reactor) improvement ▪ The inverter is installed near a large-capacity power supply. Harmonic ▪ Effects of harmonics on the power supply is FR-HC (High power factor converter) suppression worrying. ▪ It is harder to hear a radio due to noise if the FR-BIF (Radio noise filter) Measures inverter is installed. FR-BLF (Line noise filter) against noise ▪ A leakage current of the inverter is worrying. FR-BLF (Line noise filter) ▪ To decelerate quickly even if the inertia BU, FR-BU type brake unit moment of a machine is large (Brake unit + Brake resistor) Braking ▪ The enough braking capacity is required FR-CV, FR-RC type power regeneration capability UP since acceleration/deceleration is frequently converter performed. ▪ To make various settings FR series manual controller Applied ▪ To perform the line control and synchronous operation operation ▪ To place the exothermic section of the FR-A7CN Installation inverter outside the enclosure and make it Heatsink outside attachment smaller than the panel size * Supplied for the inverters of 75K or more Operation
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7.3 Power Supply Capacity
The power supply capacity (transformer capacity) on the inverter input side can be calculated by Formula (7.1).
Power supply capacity = Motor capacity (kW) [kVA] Total efficiency of the inverter X Inverter power factor (Total efficiency of the inverter = Motor efficiency X Inverter efficiency) (7.1)
The inverter power factor varies depending on the load and power supply conditions. Therefore, set the power supply capacity (transformer capacity) to 1.2 to 1.5 times as large as the inverter output kVA with the assumption that the inverter efficiency is 0.6 to 0.8 and in consideration for the influence of a voltage drop at a power-on of the inverter. The power factor of the inverter with the power factor improving reactor is calculated with FR-BEL: 0.93 and FR-BAL: 0.88. The power supply capacity (kVA) is described in a catalog.
7.4 Moulded Case Circuit Breaker (MCCB)
MCCB is used to prevent the power supply side distribution line from being damaged due to an overload and a current at short-circuited. 1) Selecting the rated current For selecting the MCCB breaking capacity, refer to "Mitsubishi No-Fuse Breaker Instruction Manual". 2) Selecting the rated current The size of the inverter input current (effective value) varies depending on the input current form factor. The input current form factor is affected by the power supply impedance. Therefore, set the rated current to 1.4 times or more as large as the input current effective value in consideration for the influence of the harmonic components as well as for the size of the effective value. 3) For selecting the MCCB type and the rated current to avoid the false tripping at the peak value of the inrush current at power on, refer to "Selection of peripheral devices" in the catalog.
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7.5 Earth Leakage Current Breaker (ELB)
1) Leakage current of cable path Since the inverter output waveform includes high frequency components, the leakage current of the cable path from the inverter to the motor during the inverter operation becomes larger than that during the commercial operation. Therefore, if the inverter is use for the existing facilities, the ELB may trip. 2) Selecting the rated sensitivity current Calculate the rated sensitivity current from the continuous leakage current of the cable and motor. The size of the continuous leakage current varies according to conditions such as the motor capacity, cable length, insulation type and cable laying.
The output side leakage current during the inverter operation is approximately 3 times as large as that with the commercial power supply.
In addition, if Mitsubishi New Super NV is used, the same sensitivity current as for the commercial operation can be selected.
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7.6 Input Side Magnetic Contactor (MC)
(1) Necessity of installation The purposes of installing the magnetic contactor (MC) on the input side are described as follows. 1) To avoid restarting by power restoration at an occurrence of the instantaneous power failure 2) To disconnect the inverter from the power supply at inverter fault or maintenance When cycle operation or heavy-duty operation is performed with an optional brake resistor connected, overheat and burnout of the electrical-discharge resistor can be prevented if a regenerative brake transistor is damaged due to insufficient heat capacity of the electrical-discharge resistor and excess regenerative brake duty. 3) To rest the inverter for an extended period of time (Use MC to save power.)
For cautions for turning on/off the input side magnetic contactor (MC), refer to Section 3.5.5.
(2) Capacity selection method Since installing the input side magnetic contactor (MC) is not for the start/stop of the inverter, the electrical life does not lead to problems. Select a capacity which meets the inverter input current. Refer to "Selection of peripheral devices" in the catalog for selecting the input side magnetic contactor (MC).
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Good to know for checking an inverter
Since the inverter has a large-capacity smoothing electrolytic capacitor on the converter circuit, it is seen as a capacitor input type rectifier from the power supply side. Therefore, the pulsed current for charging the capacitor flows to the inverter input side. This current form factor is reduced greater than the sine wave current for the commercial power supply, and the power factor becomes lower.
Input current (3-phase) Input voltage
Inverter stop
Inverter stop refers to when the base circuit for the transistor is shut off. The inverter does not stop until the deceleration time elapses even if the start terminal (STF or STR) is turned off. Also, the inverter continues to operate, though the motor stops if the output side MC is turned off. Therefore, turn off the start terminal or turn on the output stop terminal (MRS or reset terminal RES) to shut off the base circuit for the transistor. If the inverter is turned off, however, the inverter stops since the base circuit for the transistor is shut off immediately. Even if turned on, the inverter keeps the output stop until the start signal is turned on.
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7.7 Surge Suppression Filter
In the PWM type inverter, a surge voltage attributable to wiring constants is generated at the motor terminals. Especially for a 400V class motor, the surge voltage may deteriorate the insulation. When the 400V class motor is driven by the inverter, consider the following measures.
7.7.1 Corrective action
It is recommended to perform any of the following actions. (1) Rectifying the motor insulation For the 400V class motor, use an insulation-enhanced motor. Specifically, 1) Specify the "400V class inverter-driven insulation-enhanced motor". 2) For the dedicated motor such as the constant-torque motor and low-vibration motor, use the "inverter-driven, dedicated motor". (2) Suppressing the surge voltage on the inverter side Connect a filter on the secondary side of the inverter to suppress the surge voltage so that the terminal voltage of the motor is 850V or less. When using our inverter to drive the motor, connect an optional surge voltage suppression filter on the secondary side of the inverter.
For the surge voltage suppression filter, FR-ASF-H□□K or FR-BMF-H□□K is selectable.
FR-BMF-H□□K can be installed on the rear panel (up to 22K) or side panel of the inverter and is available for designing in various panels. For using the surge voltage suppression filter, the maximum wiring length must be within 100m, and the carrier frequency within 2kHz.
Rear panel installation
Side panel installation
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7.7.2 Outline dimension drawings
Dimensions (mm) Model FR-ASF-H1.5K FR-ASF-H3.7K FR-ASF-H7.5K FR-ASF-H15K※ FR-ASF-H22K※ FR-ASF-H37K※ FR-ASF-H55K※ Applicable inverter 0.4K/0.75K/1.5K 2.2K/3.7K 5.5K/7.5K 11K/15K 18.5K/22K 30K/37K 45K/55K W 220 220 280 335 335 375 395 D 160 180 215 285 349 429 594 H 193 200 250 260 340 465 465 T 2.3 3.2 3.2 6 6 6 6 W1 200 200 255 310 310 350 370 D1 134 155 191 235 281 - - Approx. Terminal Installation mass (kg) screw J screw 95 6×17 M4 M5 8.0 115 6×18 M4 M5 11 125 8×24 M6 M6 20 200 φ10 M6 M8 28 240 φ10 M8 M8 38 340 φ10 M8 M8 59 490 φ10 M10 M8 78 *For H15K or later, some configurations differ. D2 C×E
Ground screw
Terminal screw J
Surge voltage suppression filter FR-ASF-H□□K
(2) FR-BSF-H□□K FR-BMF-H7.5K to H22K
Installation hole for 2-d
Installation hole for 2-d
Earth (Ground) terminal
Installation hole for 2-d Red White Blue (U) (V) (W) Insulation cap color Main terminal block (d1) Control terminal block (M3)
Installation hole for 2-d
Model FR-BMF-H7.5K FR-BMF-H7.5K,H22K
Dimensions (mm) D D1 75 100 45 50
d M5 M8
d1 M4 M5
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Installation hole for 2-M8
Earth (Ground) terminal
Terminal layout
Red White Blue
Installation hole for 2-M8
Main terminal block (M6)
Insulation cap color
Control terminal block (M3)
Good to know
For the inverter of 75K or more, the motor voltage and current can be made to nearly sine wave shaped by providing a sine wave filter on the output side. As a result of this, the same characteristic as when the motor is driven with a sine wave power supply is obtained and the following result can be expected. 1) Low noise 2) Surgeless 3) Motor loss reduction (use of standard motor)
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7.8 Output Side Magnetic Contactor (MC)
As a general rule, the magnetic contactor (MC) installed on the inverter output side must not be turned on during the inverter operation. When the output side magnetic contactor (MC) is turned on during the operation, an overcurrent trip occurs in the inverter due to the large start current. The output side magnetic contactor (MC) can be shut off during the operation. However, the motor coasts to stop at that time. The purposes of installing the magnetic contactor (MC) on the output side are described as follows: 1) To configure the commercial power supply-inverter switch-over circuit 2) To switch multiple motors with one inverter (Switch the motors during an inverter stop.) 3) To need to disconnect the motor from the cable path in the operation cycle while it is at a stop.
For cautions on turning on/off the output side magnetic contactor (MC), refer to Section 3.5.4.
7.9 Thermal Relay (OCR)
(1) The overload protection of the standard motor is performed with the inverter built-in electronic thermal. However, the protection cannot be performed for the following cases, and therefore install a thermal relay between the motor and the inverter. 1) To drive multiple motors with a single inverter
NFB Power supply Inverter OCR IM OCR Motor IM
2) To drive a special motor whose thermal characteristic differs from that of the standard motor [Example] Submersible motor, multi-pole motor (8 poles or more) or other motors 3) To perform the commercial power supply-inverter switchover operation
NFB Power supply Inverter
Motor IM
(2) Thermal setting value Thermal setting value is a current value at 50Hz on the motor rating plate. (3) Since the inverter output waveform is not a sine wave and includes high frequency components, a commercially available electronic thermal relay cannot be used
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7.10 Cable Size of Main Circuit
Select the cable size of the main circuit according to the voltage, current, ambient temperature and wiring distance. (1) Inverter input side Select a cable size which meets the input current. (Refer to the size shown in a catalog.) (2) Inverter output side Select a cable size which meets the motor current as well as on the input side. Especially, if the wiring distance between the inverter and motor is long, the decrease of motor output torque and the increase of heat generation may occur due to the voltage drop. Select an adequate size. The size shown in a catalog is selected for the distance of 20m.
Good to know for checking an inverter
Since the inverter output voltage is almost proportional to the output frequency, the output voltage is smaller in the low-frequency range, and the voltage drop ratio [%] is larger even if the voltage drop [V] of a cable is same as at 50 to 60Hz.
7.11 Power Factor Improving Reactor (Either FR-HAL or FR-HEL)
(1) Purpose for use Since the power factor on the inverter input side is low, connect the power factor improving reactor to the inverter input side (for FR-HAL) or the inverter DC side (for FR-HEL) to improve the power factor. (2) Effects The power factor is approximately 88% for the power factor improving AC reactor (FR-HAL), and approximately 93% for the power factor improving DC reactor (FR-HEL). The following effects are obtained in addition to the power factor improvement. 1) The power supply capacity can be decreased. <<Since the power factor improves>> 2) Rated values of the equipments used on the inverter input side can be reduced. <<Since the input current becomes lower>> 3) The harmonic components included in the input side current decrease. 4) The increase of the capacitor terminal voltage due to the transitional increase of the power supply voltage is suppressed to prevent the overvoltage trip (OV1 to OV3). (3) Capacity selection Select the capacity according to the motor capacity and the voltage specification. For the power factor improving AC reactor (FR-HAL), a voltage drop of approximately 2% occurs (at the rated load). Caution is required for the insufficient torque.
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7.12 Inverter Setup Software
FR Configurator(FR-SW2-SETUP-WJ) The inverter setup software provides a comfortable operating environment of the inverter as a support tool for operations from startup to maintenance of the inverter. The parameter setting, monitoring, etc. are enabled efficiently on the Windows screen of a personal computer. (1) Functions ▪ Parameter setting and edit ............ The All list format, Functional List Format, Individual List Formal, Basic Settings, I/O terminals Allocation and Convert Function are provided. ▪ Monitoring...................................... The Data display, I/O terminal monitor, Oscilloscopes and Status Monitor are provided. ▪ Test operation ............................... Used to judge whether the inverter can operates normally without an operation sequence to the inverter. ▪ Diagnosis....................................... Internal diagnosis for judging the inverter operation status ▪ System setting............................... Used to perform the data write and data read to multiple inverter systems. ▪ File................................................. Used to save the parameters, operation data, etc. to a hard disk or floppy disk. ▪ Windows........................................ Multiple screens can be displayed. (2) System configuration
Motor NFB Power supply Personal computer Inverter IM
Inverter Setup software
(Note: A commercially available converter is required for RS-232C.)
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(3) Screen examples
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Excerpts from operations of convert function (Inverter unconnected)
By starting FR Configurator, the following screen is displayed. This section describes the setting for the station number, model, capacity and plug-in option of inverter to be connected. The inverters can be set from 00 to 31 stations. The connected inverter system can be also read all at once.
Double-click on the line of the station number to display the VFD structure panel of the inverter. After adding or changing the inverter model (e.g. FR-A720) or capacity (e.g. 0.4K), make sure to press the Confirmed button.
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No. A
Name System setting
Function and description Sets the environment of an inverter from 00 to 31 stations.
Select a model and capacity of inverter. Set a type of plug-in option when using a plug-in option.
By double-clicking on the line of station number to be set, the "VFD Structure" panel is displayed. Set model, capacity and option, and press the OK button to complete the setting. With the same procedures, set all the inverter stations to be connected.
New button System Read button
Confirmed button
By clicking the New button, the edited system setting and communication setting are initialized (cleared), and a new system is set. Before pressing the System Read button, change the system to the online mode by pressing the ONLINE button. In the online mode, the system is in the status of communicating with the inverter. By clicking the System Read button, the models, capacities and options of all stations (0 to 31 stations) are read, and connected (communicable) stations are displayed. Automatically confirmed after the read. When the system setting has been already registered, the verification is performed. When the verification result is different from the read data, display the result of checking, and select to change the settings or not. The data set the system setting can be confirmed. When the setting of the system configuration is changed manually, make sure to confirm using the Confirmed button.
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Converting parameters automatically at the replacement of the conventional model [Convert Function]
By selecting the [Convert Function] command in the [Parameter] menu, the parameters of the conventional model inverter can be automatically converted to those of FR-A700/F700 series of the same model type. Source inverter FR-A520, FR-A520L, FR-V520, FR-V520L FR-A540, FR-A540L, FR-V540, FR-V540L FR-F520, FR-F520L FR-F540, FR-F540L Target inverter FR-A720 FR-A740 FR-F720 FR-F740
[Source inverter setting section]
No. A B C D E F G H I Name Source model selection setting Source model selection Source capacity selection Parameter file conversion setting Connected inverter selection Fixation button Source model /capacity display Source parameter data list Target model Function and description Turning on the checkbox to select the model and the capacity from the list. Selects the model of source inverter from the list in the combo box. Selects the capacity of source inverter from the list in the combo box. Turning on the checkbox makes the parameter file input field valid. Input the storage place for the parameter file (PRM file). Turning on the checkbox makes the station number selection available. Specify the station number of source inverter. Clicking Fixation after making the source inverter setting, and then the target inverter setting can be made. Displays the model and capacity of the read parameter. Lists the data of the read parameter. The setting value can be changed. Selects the model of target inverter from the list in the combo box. - 168 -
selection J K Start Conversion button Save Data button Clicking here starts the conversion. Clicking the Save Data button displays the Save as dialogue, and the parameter data is saved with specifying a file. The format of the file is Parameter file (PRM file) only.
[Source inverter setting section]
No. L Name Target model/capacity display Target parameter data list Function and description Displays the inverter model and capacity of the converted parameter.
Displays the converted parameter list. The setting value can be changed. The number of parameter whose setting has been made is displayed in red.
[Common section]
No. N Name Simultaneous scroll of the list of parameters Checked Function and description : When either of the source or target parameter lists is scrolled, the other list is also scrolled. Not checked: When either of the source or target parameter lists is scrolled, the other list does not scroll.
● Conversion procedure by selecting a model from a list
(1) Check "Select the model from the list" in the "Set VFD from which conversion is made" selection and select the model and capacity of the source inverter.No.A,B,C (2) Click Fixation. When it is fixed, the parameters of the selected model and capacity are displayed as a list.No.F (3) When the parameter setting value of the utilized source inverter has been changed, input the changed value in the Set Value column. (4) Select the model of the target inverter. (Only models convertible with FR Configurator are selectable.) No.I
- 169 Displayed in green when the setting value is changed. When changing the Pr.1 setting value to "g60Hz"
(5) Click Start Conversion to display the parameter conversion result as a list. No.J (6) Click Save Data to save the conversion result in the parameter file (PRM).No.K (7) Display the All List Format or the Functional List Format from Parameter of the menu, and open the saved parameter file (PRM).
(8) Change the target inverter to ONLINE and click Blk Write. The parameter setting value is written in the inverter, and conversion is completed. Since the inverter is not connected in this demonstration, writing to the inverter cannot be performed.
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A general-purpose inverter is a static unit mainly consisting of semiconductor devices. Daily inspection must be performed to prevent any fault from occurring due to the adverse effects of the operating environment, such as temperature, humidity, dust, dirt and vibration, changes in the parts with time, service life, and other factors.
8.1 Precautions for Maintenance and Inspection
For some time after the power is switched off, a high voltage remains in the smoothing capacitor. When accessing the inverter for inspection, wait until the charge lamp is turned off, and then make sure that the voltage across the main circuit terminals P-N of the inverter is not more than 30VDC using a tester, etc.
8.2 Inspection Items
(1) Daily inspection
●Basically, check for the following faults during operation.
1) Whether the motor operates properly as set 2) Improper installation environment 3) Cooling system fault 4) Unusual vibration and noise. 5) Unusual overheat and discoloration
● During operation, check the inverter input voltages using a tester.
(2) Periodic inspection
● Check the areas inaccessible during operation and requiring periodic inspection.
1) Cooling system fault .......................... Clean the air filter, etc. 2) Tightening check and retightening .....The screws and bolts may become loose due to vibration, temperature changes, etc. 3) Check the conductors and insulating materials for corrosion and damage. 4) Measure the insulation resistance. 5) Check and change the cooling fan and relay.
(Note) A general-purpose inverter has a power supply indication, which tells that the inverter is in operation, and error (alarm) indications at trouble occurrences. Understand the contents of these indications. Also, check the data of the electronic thermal relays, acceleration/deceleration time, etc. using the parameter unit, and record their setting values for normal operation.
For the inspection items and criteria of the daily and periodic inspections, refer to the table provided on the next page.
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Daily and periodic inspection
Area of inspectio n Interval Inspection item Inspection point Daily Surrounding environment General Overall unit Power supply voltage Check the ambient temperature, humidity, dirt, corrosive gas, oil mist, etc. Check for unusual vibration and noise. Check that the main circuit voltages and control voltages are normal. *1 (1) Check with megger (across main circuit terminals and earth (ground) terminal). (2) Check for loose screws and bolts. (3) Check for overheat traces on the parts. (4) Check for stain. Periodi c
Corrective action at alarm occurrence
Customer's check
Improve environment. Confirm where the faulty area is, and tighten accordingly. Inspect the power supply. Contact the manufacturer. Retighten. Contact the manufacturer. Clean. Contact the manufacturer. Contact the manufacturer. Stop the device and contact the manufacturer. Stop the device and contact the manufacturer. Contact the manufacturer. Contact the manufacturer. Contact the manufacturer. Contact the manufacturer. Contact the manufacturer. Contact the manufacturer. Contact the manufacturer.
(1) Check conductors for distortion. Conductors, cables (2) Check cable sheaths for breakage and deterioration (crack, discoloration, etc.). Transformer/reacto Check for unusual odor and abnormal increase in r whining sound. Terminal block Smoothing aluminum electrolytic capacitor Relay/contactor Resistor Check for damage. (1) Check for liquid leakage. (2) Check for safety valve projection and bulge. (3) Visual check and judge by the life check of the main circuit capacitor. Check that the operation is normal and no chatter is heard. (1) Check for crack in resistor insulation. (2) Check for a break in the cable. (1) Check that the output voltages across phases with the inverter operated alone is balanced. (2) Check that no fault is found in protective and display circuits in a sequence protective operation test. (1) Check for unusual odor and discoloration. All parts Parts check Aluminum electrolytic capacitor (2) Check for serious rust development. (1) Check for liquid leakage in a capacitor and deformation trance. (2) Visual check and judge by the life check of the control circuit capacitor. (1) Check for unusual vibration and noise. (2) Check for loose screws and bolts. (3) Check for stain. (1) Check for clogging. (2) Check for stain. (1) Check for clogging. (2) Check for stain. (1) Check that display is normal. (2) Check for stain. Check that reading is normal. Check for vibration and abnormal increase in operation noise.
Main circuit
Operation check Control circuit/ protective circuit
Stop the device and contact the manufacturer. Contact the manufacturer. Contact the manufacturer.
Cooling fan Cooling system
Replace the fan. Retighten. Clean. Clean. Clean. Clean or replace. Clean or replace. Contact the manufacturer. Clean. Stop the device and contact the manufacturer. Stop the device and contact the manufacturer.
Air filter, etc.
Display Display Meter Load motor Operation check
*1 It is recommended to install a device that monitors power supply voltages applied to the inverter. *2 A year or two is recommended as a cycle of periodic inspection. However, this may differ depending on the installation environment. For periodic inspection, consult the nearest Mitsubishi FA Center.
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8.3 Replacement of Parts
An inverter consists of many electronic parts such as semiconductor devices. The following parts may deteriorate with age because of their structures or physical characteristics, leading to reduced performance or fault of the inverter. For preventive maintenance, the parts must be replaced periodically. For FREQROL-A700 and F700 series, use the life check function as a guidance of parts replacement. (1) Cooling fan The cooling fan, which is used for heat-generating parts such as the main circuit semiconductor devices, has a bearing. This bearing is estimated to serve for approximately 87600 hours (for the FREQROL-A700 and F700 series). This is equivalent to approximately 10 years if the unit with the cooling fan is continuously operated without any stop. Replace the whole cooling fan when replacing. Exceptionally, when unusual noise and/or vibration is noticed during inspection, the cooling fan must be replaced immediately. The FREQROL-A700 and F700 series provide a function to set the ON/OFF control of the cooling fan. With the ON/OFF control, the service life of the cooling fan can be extended. Replacement is also made easily with a cassette. (2) Smoothing capacitor A large-capacity aluminum electrolytic capacitor is used for smoothing in the main circuit DC section, and an aluminum electrolytic capacitor is used for stabilizing the control power in the control circuit. Their characteristics are deteriorated by the adverse effects of ripple currents, etc. The replacement intervals greatly vary with the ambient temperature and operating conditions. When the inverter is operated in air-conditioned, normal environment conditions, replace the capacitors about every 10 years (for the FREQROL-A700 and F700 series). When a certain period of time has elapsed, the capacitors will deteriorate more rapidly. Check the capacitors at least every year (less than six months if the life will be expired soon). The appearance criteria for inspection are as follows: 1) Case: Check the side and bottom faces for expansion. 2) Sealing plate: Check for remarkable warp and extreme crack. 3) Explosion-proof valve: Check valves for significant extension, and check valves that have operated 4) Check for external crack, discoloration, fluid leakage, etc. Judge that the capacitor has reached its life when the measured capacitance of the capacitor reduced below 85% of the rating.
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(3) Relays To prevent a contact fault, etc., relays must be replaced according to the cumulative number of switching times (switching life). The following table shows replacement criteria for the inverter parts. Note that parts with a short service life such as lamps must be replaced at periodic inspection. Replacement parts of inverter (FREQROL-A700, F700 series) Part name Standard replacement Description interval Cooling fan 10 years Replace with a new product (as required). Main circuit smoothing 10 years Replace with a new product (as required). capacitor On-board smoothing 10 years Replace with a new board (as required). capacitor Relays Replace as required. ――
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8.4 Measurement of Main Circuit Voltages, Currents and Powers
● Measurement of voltages and currents
Since the voltages and currents on the inverter power supply and output sides include harmonics, measurement data depends on the circuits measured. When instruments for commercial frequency are used for measurement, measure the following circuits with the instruments given on the next page.
Input voltage
Output voltage
Input current
Output current
Inverter Ar 3-phase power supply Vr As Vs At Vt P 2 N 5
Au Vu Av Vv Aw Vw
To the motor
Moving-iron type Electrodynamometer type
+ Instrument types
Moving-coil type Rectifier type
Examples of measuring points and instruments
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Measuring points and instruments
Measuring item Power supply voltage V1 Power supply side current I1 Power supply side power P1 Power supply side power factor Pf1 Measuring point Measuring instrument Remarks (reference measured value) *
Moving-iron type AC voltmeter
Within permissible commercial power supply AC voltage fluctuation
(Refer to Section 6.1.7
R, S, and T line currents Moving-iron type AC ammeter
R, S, T and R-S, S-T, T-R
Electrodynamic type single-phase wattmeter
P1=W11+W12+W13 (3-wattmeter method)
Calculate after measuring power supply voltage, power supply side current and power supply side power.
Pf1 P1 3 V1I1 100
Output side voltage V2
Rectifier type AC voltmeter (Note 1) (not the moving-iron type) Moving-iron type AC ammeter (Note 2)
Electrodynamic type single-phase wattmeter
Difference between the phases is 1% of the maximum within output voltage. Current should be equal to or less than rated inverter current. Difference between phases is 10% or less. P2=W21+W22
Output side current I2 Output side power P2 Output side power factor Pf2
U, V and W line currents
U, V, W and U-V, V-W
2-wattmeter method (or 3-wattmeter method)
Calculate in a similar manner to the power supply side power factor.
Pf2 P2 3 V2 I2 100
Converter output
Moving-coil type (Tester, etc.)
Frequency setting power supply
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"5" is common.
Frequency setting signal
POWER lamp turns on. 1.35×V1 Maximum 380V (760V) regeneration 0 to 5VDC/0 to 10VDC 0 to 5VDC/0 to 4 to 20mADC 5VDC
Moving-coil type (Tester and such may be used) (Internal resistance: 50kΩ or larger)
Approx. 5VDC at maximum frequency
(without frequency meter)
Moving-coil type (Tester and such may be used) (Internal resistance: 50kΩ or larger) AM(+)-5
Pulse width T1: Adjust with Pr. 900 Pulse cycle T2: Set with Pr. 55 (valid only for frequency monitor) Approx. 10VDC at maximum frequency (without frequency meter) When open 20 to 30VDC ON voltage: 1V or less Continuity check<Normal> <Abnormal> A-C Discontinuity Continuity B-C Continuity Discontinuity
Start signal Select signal Reset Output stop Alarm signal
STF, STR, RH, RM, RL, JOG, RT, AU, STOP, CS(+)-SD RES(+)-SD MRS(+)-SD A-C B-C Moving-coil type (Tester, etc.)
(Note 1) Since a tester produces a large error, correct value cannot be measured by a tester. (Note 2) When the carrier frequency exceeds 5KHz, do not use this instrument since using it may increase eddy-current losses produced in metal parts inside the instrument, leading to burnout. In this case, use an approximate-effective value type. * Values in parentheses indicate those for the 400V series.
8.5 List of Alarm Display
The following table shows error sources that are shown on the display of the operation panel when erroneous operation is detected. (FREQROL-A700 series)
Operation panel indication E--HOLD Error message Er1 to 4 Name Alarm history Operation panel lock Parameter write error Major fault Operation panel indication E.ILF* E.OLT E.GF Name Input phase failure Stall prevention Output side earth (ground) fault overcurrent Output phase failure External thermal relay operation PTC thermistor operation
rE1 to 4 Err.
Copy operation error Error Stall prevention (overcurrent)
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"SD" is common.
Frequency meter signal
oL RB TH Alarms PS MT CP SL
Stall prevention (overvoltage) Regenerative brake pre-alarm Electronic thermal relay pre-alarm PU stop Maintenance signal output Parameter copy Speed limit indication (speed restriction output) Fan failure
E.OPT E.OP1 to OP3 E. 1 to E. 3 E.PE E.PUE E.RET E.PE2*
Option alarm Communication option alarm Option alarm Parameter storage device alarm PU disconnection Retry count excess Parameter storage device alarm
CPU error
Overcurrent shut-off during acceleration Major fault
Operation panel power supply short circuit, RS-485 terminal power supply short circuit
24VDC power supply output short circuit Output current detection value excess Inrush current limit circuit alarm Communication error (inverter)
E.OV1 Major fault
Overcurrent shut-off during constant speed Overcurrent shut-off during deceleration or stop Regenerative overvoltage shut-off during acceleration Regenerative overvoltage shut-off during constant speed Regenerative overvoltage shut-off during deceleration or stop Inverter overload shut-off (electronic thermal relay function) Motor overload shut-off (electronic thermal relay function) Heatsink overheat Instantaneous power failure Undervoltage
Analog input error
Overspeed occurrence
Speed deviation excess detection Open cable detection
Position error large
E.MB1 to Brake sequence error E.MB7
* If an error occurs when using with the FR-PU04, "Fault 14" is displayed on the FR-PU04.
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Operation panel indication E.EP Major fault E. BE E. USB* E.13 E.11
Name Encoder phase error Brake transistor error detection USB communication error Internal circuit error Opposite rotation deceleration error
* If an error occurs when using with the FR-PU04, "Fault 14" is displayed on the FR-PU04.
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8.6 Abnormal Phenomenon and Check Points
If the cause is still unknown after every check, it is recommended to initialize the parameters (initial value) then re-set the required parameter values and check again.
8.6.1 Motor does not rotate as commanded.
1) Check the Pr. 0 "Torque boost" setting. 2) Check the main circuit.
Check that a proper power supply voltage is applied. (Operation panel display is provided.) Check that the motor is connected properly. Check that the jumper across P/+-P1 is connected.
3) Check the input signals.
Check that the start signal is input. Check that both the forward and reverse rotation start signals are not input simultaneously. Check that the frequency command value is not zero. (If the frequency command is 0Hz and the start signal is entered, the LED of FWD or REV on the operation panel flickers.) Check that the AU signal is on when the frequency setting signal is 4 to 20mA. Check that the output stop signal (MRS) or reset signal (RES) is not on. Check that the CS signal is not off with automatic restart after instantaneous power failure function is selected (Pr. 57 ≠ "9999"). Check that the sink or source jumper connector is fitted securely.
4) Check the parameter settings.
Check that the Pr. 78 "Reverse rotation prevention selection" is not selected. Check that the Pr. 79 "Operation mode selection" setting is correct. Check that the bias and gain (calibration parameters C2 to C7) settings are correctly made. Check that the Pr. 13 "Starting frequency" setting is not greater than the running frequency. Check that frequency settings of each running frequency (such as multi-speed operation) are not zero. Check especially that the Pr. 1 "Maximum frequency" is not zero. Check that the Pr. 15 "Jog frequency" setting is not lower than the Pr. 13 "Starting frequency" value.
5) Inspect the load
Check that the load is not too heavy. Check that the shaft is not locked.
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8.6.2 Motor generates abnormal noise.
No carrier frequency noises (metallic noises) are generated. Soft-PWM operation to change the motor tone into an unoffending complex tone is factory-set to valid by the Pr. 72 "PWM frequency selection". Adjust Pr. 72 "PWM frequency selection" to change the motor tone. Check that the gain value is not too high during the real sensorless vector control or vector control. Check the value of the Pr. 820 (Pr. 830) "Speed control P gain" when speed control is exercised and the Pr. 824 (Pr. 834) "Torque control P gain" when torque control is exercised. Check for any mechanical looseness. Contact the motor manufacturer.
8.6.3 The motor generates heat abnormally.
Check that the fan for the motor is running. (Check for dirt accumulated.) Check that the load is not too heavy. Lighten the load if too heavy. Check that inverter output voltages (U, V, W) are balanced. Check that the Pr. 0 "Torque boost" setting is correct. Check that the motor type is set. To do this, check the Pr. 71 "Applied motor" setting. When using any other manufacturer's motor, perform offline auto tuning.
8.6.4 The motor rotates in opposite direction.
Check that the phase sequence of output terminals U, V and W is correct. Check that the start signals (forward rotation, reverse rotation) are connected properly.
8.6.5 Speed greatly differs from the setting.
Check that the frequency setting signal is correct. (Measure the input signal level.) Check that Pr. 1, Pr. 2, Pr. 19 and the calibration parameters C2 to C7 are correct. Check that the input signal lines are not affected by external noise. (Use shielded cables.) Check that the load is not too heavy. Check that the Pr. 31 to Pr. 36 (frequency jump) settings are correct.
8.6.6 Acceleration/deceleration is not smooth.
Check that the acceleration and deceleration time settings are not too short. Check that the load is not too heavy. Check that the torque boost setting (Pr. 0, Pr. 46, Pr. 112) is not too large to activate the stall function (torque limit).
8.6.7 Motor current is large.
Check that the load is not too heavy. Check that the Pr. 0 "Torque boost" setting is correct. Check that the Pr. 3 "Base frequency setting" is correct. Check that the Pr. 19 "Base frequency voltage" is correct. Check that the Pr. 14 "Load pattern selection" is appropriate.
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8.6.8 Speed does not increase.
Check that the Pr. 1 "Maximum frequency" setting is correct. (If you want to run the motor at 120Hz or more, set Pr. 18 "High speed maximum frequency".) Check that the load is not too heavy. (In agitators, etc., load may become heavier in winter.) Check that the torque boost setting (Pr. 0, Pr. 46, Pr. 112) is not too large to activate the stall function (torque limit). Check that the brake resistor is not connected to terminals P/+-P1 accidentally.
8.6.9 Speed varies during operation.
When advanced magnetic flux vector control or real sensorless vector control is exercised, the output frequency varies with load fluctuation between 0 and 2Hz. This is a normal operation and is not a fault.
1) Inspect the load.
Check that the load is not varying.
2) Check the input signals.
Check that the frequency setting signal is not varying. Check that the frequency setting signal is not affected by noise. Input filter to the analog input terminal using Pr. 74 "Input filter time constant" and Pr. 822 "Speed setting filter 1". Check for a malfunction due to undesirable currents when the transistor output unit is connected.
3) Others
Check that the value of Pr. 80 "Motor capacity" and Pr. 81 "Number of motor poles" are correct to the inverter capacity and motor capacity under the advanced magnetic flux vector control and real sensorless vector control. Check that the wiring length is not exceeding 30m when the advanced magnetic flux vector or real sensorless vector control is exercised. Perform offline auto tuning. Check that the wiring length is not too long for the V/F control.
8.6.10 Operation mode is not changed properly.
If the operation mode does not change correctly, check the following:
1) Inspect the ………Check that the STF or STR signal is off. When it is on, the operation mode cannot be changed load. 2) setting Parameter ………Check the Pr. 79 setting.
When the Pr. 79 "Operation mode selection" setting is "0" (initial value), the inverter is placed in the external operation mode at input power-on. At this
time, press EXT on the operation panel (press PU when the parameter unit (FR-PU04/FR-PU07) is used) to switch to the PU operation mode. For other values (1 to 4, 6, 7), the operation mode is limited accordingly.
8.6.11 Control panel (FR-DU07) display is not operating.
Check that the operation panel is connected to the inverter securely.
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8.6.12 POWER lamp does not turn on.
Check that wiring and installation are made securely.
8.6.13 Parameter write cannot be performed.
Make sure that operation is not being performed (signal STF or STR is not ON). Make sure that you are not attempting to set the parameter in the external operation mode. Check Pr. 77 "Parameter write selection". Check Pr. 161 "Frequency setting/key lock operation selection".
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8.7 Protective Function
When a protective function (major fault) is activated, power the inverter off and power it on again, or reset the inverter using the reset terminal (RES). (Alternatively, reset the inverter using the Help menu of the PU.) (1) Error message A message regarding operational troubles is displayed. Output is not shut off.
Function name Operation panel lock Description Appears when operation was tried during operation panel lock. Display HOLD Check the settings of Pr. 77, Pr. 31 to Pr. 36, and Pr. 100 Er1 to Pr. 109. Check the connection of the PU and inverter. Check the Pr. 77 setting. Parameter write error Appears when an error occurred during parameter writing Er3 Er2 Check that the inverter is not operating. Check the settings of the calibration parameters C3, C4, C6 and C7. Check that the operation mode is "PU operation mode". Check the Pr. 77 setting. rE1 rE2 Check that the FWD or REV LED is lit or flickering. Check for the parameter rE3 Copy operation error Appears when an error occurred during parameter copying. setting of the source inverter and inverter to be verified. Check that the verified inverter is the same model. Check that operation is not rE4 stopped by switching off the power supply while reading parameter copy or by disconnecting the operation panel. Appears when the RES signal is on or Error the PU and inverter cannot make normal communication. Err Turn off the RES signal. Check the connection of the PU and inverter. Use the same model for parameter copy and verification. Make parameter copy again. Perform again after stopping operation. Press
Check point Press
Corrective action
for 2s to release lock.
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(2) Alarm When the protective function is activated, the output is not shut off.
Function name Description Display Check point Check that the load is not too Stall prevention (overcurrent) heavy. Check that the setting Appears during overcurrent stall prevention. OL values of Pr. 0 and Pr. 13 are not too large. Check that the setting values of Pr. 7 and Pr. 8 are not too short. Stall prevention (overvoltage) Appears during overvoltage stall prevention. Appears while the regeneration avoidance function is activated.
Corrective action Reduce the load weight. Change the settings of Pr. 0, 7, 8, 13 and 14. Increase capacities of the motor and inverter.
Check for sudden speed oL reduction. Check that the regeneration avoidance function is used. Check for a stop made by PS
Increase the deceleration time using Pr. 8. Turn the start signal off and release with
Appears when PU stop panel was operation.
on the operation during external
pressing panel.
of the operation
Appears when the regenerative brake Regenerative duty reaches or exceeds 85% of the brake pre-alarm setting of Pr. 70. If the regenerative brake duty reaches 100%, a regenerative overvoltage (E. OV_) occurs. Appears when the integrating value of Electronic thermal relay pre-alarm the electronic thermal relay function reaches or exceeds 85% of the Pr. 9 setting. If it reaches 100% of the Pr. 9 setting, a motor overload shut-off (E. THM) occurs. Maintenance signal output Parameter copy Appears when the cumulative energization time has exceeded the maintenance output timer set value. Appears when parameters are copied between models with capacities of 55K or less and 75K or more. CP MT TH RB
Check that the brake resistor duty is not high. and Pr. 70 are correct. Increase the deceleration time. Check that the settings of Pr. 30 Correct Pr. 30 and Pr. 70.
Check for large load or sudden acceleration. Check that the Pr. 9 setting is appropriate. Check that the Pr. 503 setting is not larger than the Pr. 504 setting.
Reduce the load weight or the number of operation times. Set an appropriate value in Pr. 9.
Write "0" to Pr. 503.
Set the initial value in Pr. 989. Check that the torque command Decrease the torque command
Speed limit indication
Displays when the speed restriction level is exceeded during torque control.
is not larger than required. Check that the speed restriction level is not low.
value. Increase the speed restriction level.
(3) Minor fault When the protective function is activated, the output is not shut off. The minor fault signal can also be output by setting the parameters. (Set "98" in any of Pr. 190 to Pr. 196 (output terminal function selection).)
Function name Description Display Check point Corrective action Appears when the cooling fan stops due to a fault or when operation different from the setting of Pr. 244 is performed FN Check the cooling fan for a fault. Replace the fan. during speed reduction. This indication is involved only in the inverter that contains a cooling fan.
Fan failure
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(4) Major fault When the protective function is activated, the inverter output is shut-off and an alarm output is provided.
Function name Description Display Check point Corrective action Increase the acceleration Overcurrent shut-off during acceleration Appears when the inverter output current rose to or above about 220% of the rated current during acceleration. E.OC1 time (Shorten the downward Check for sudden acceleration. Check for output short circuit. acceleration time in vertical lift application.). Check the wiring for output short circuit. Overcurrent shut-off during constant speed Overcurrent shut-off during deceleration or stop Appears when the inverter output current rose to or above about 220% of the rated current during constant-speed operation. Appears when the inverter output current rose to or above about 220% of the rated current during deceleration or a stop. Appears when regenerative energy Regenerative overvoltage shut-off during acceleration causes the inverter's internal main circuit DC voltage to reach or exceed the specified value during acceleration, or when a surge voltage occurs in the power supply system causing the shut-off to operate. Appears when regenerative energy Regenerative overvoltage shut-off during constant speed causes the inverter's internal main circuit DC voltage to reach or exceed the specified value during constant-speed operation, or when a surge voltage occurs in the power supply system causing the shut-off to operate. Appears when regenerative energy Regenerative overvoltage shut-off during deceleration or stop causes the inverter's internal main circuit DC voltage to reach or exceed the specified value during deceleration or stop, or when a surge voltage occurs in the power supply system causing the shut-off to operate. Appears when inverse-time Inverter overload characteristics cause the electronic shut-off (electronic thermal relay function) thermal relay to be activated to protect the output transistors due to that a current not less than 150% of the rated output current flows and overcurrent shut-off does not occur (220% or less). Motor overload shut-off (electronic thermal relay function) Appears when the electronic thermal relay function built in the inverter detects motor overheat exceeding the specification value due to overload or reduced cooling capability during constant-speed operation. E.THM Check the motor for use under overload. Check that the Pr. 71 setting is correct. Reduce the load weight. For a constant-torque motor, set the constant-torque motor in Pr. 71. Increase capacities of the motor and inverter. E.THT Check the motor for use under overload. Reduce the load weight. Increase capacities of the motor and inverter. E.OV3 Check for sudden speed reduction. E.OV2 Check for sudden load change. Keep load stable. Utilize the regeneration avoidance function. Use the brake unit or power regeneration common converter as required. Increase the deceleration time. Reduce the number of operation times. Utilize the regeneration avoidance function. Use the brake unit or power regeneration common converter as required. E.OV1 Check for too slow acceleration. (e.g. during downward acceleration in vertical lift load) Decrease the acceleration time. Utilize the regeneration avoidance function. E.OC3 Check for sudden speed reduction. Check for output short circuit. Check for too fast operation of the motor's mechanical brake. Increase the deceleration time. Check the wiring for output short circuit. Check the mechanical brake operation. E.OC2 Check for sudden load change. Check for output short circuit. Keep load stable. Check the wiring for output short circuit.
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Function name
Description Appears when the heatsink overheated causing the temperature sensor to be activated. Appears when a power failure occurs for longer than 15ms (this also applies to inverter input shut-off), causing the instantaneous power failure protective function to be activated to prevent the control circuit from malfunctioning. If a power failure persists for longer than 100ms, the alarm warning output is not provided, and the inverter restarts if the start signal is on upon power restoration. (The inverter continues operating if an instantaneous power failure is within 15ms.)) Appears when an error occurred in the brake circuit, e.g. damaged brake transistors. If the power supply voltage of the inverter decreases, the control circuit will not perform normal functions. In addition, the motor torque will be insufficient and/or heat generation will increase. To support such trouble prevention, this indication appears when the power supply voltage decreases to approx. 150VAC (300VAC in the 400V class) or lower. Appears when one of the three phase power input opened with the function enabled in Pr. 872. Appears 3s after the output frequency decreased to 0.5Hz due to the stall prevention being activated. Appears when an earth (ground) fault occurred on the inverter's output side (load side). Appears when one of the three phases (U, V, W) on the inverter's output side (load side) opens. Appears when the external thermal relay
Check point Check for too high ambient temperature.
Corrective action Set the ambient temperature to within the specifications. Clean the heatsink. Replace the cooling fan.
Heatsink overheat
Check for heatsink clogging. Check that the cooling fan is stopped.
Remedy the instantaneous power failure. Prepare a backup power E.IPF Find the cause of instantaneous supply for instantaneous power failure occurrence. power failure. Set the automatic restart after instantaneous power failure function.
Instantaneous power failure
Brake transistor error detection
Reduce the load inertia. E.BE Check that the frequency of using the brake is proper. Replace the inverter.
Check for start of large-capacity motor. E.UVT Check that a jumper or DC reactor is connected across terminals P/+-P1.
Check the power supply system equipment such as power supply. Connect a jumper or DC reactor across terminals P/+-P1.
Input phase failure
Check for a break in the cable E.ILF for the three-phase power supply input. E.OLT Check the motor for use under overload. Check for an earth (ground) E.GF fault in the motor and connection cable. Check the wiring. Check that the motor is normal. E.LF Check that the capacity of the motor used is not smaller than that of the inverter. Check for motor overheating. E.OHT Check that the value of 7 is set correctly in any of Pr. 178 to Pr. 189.
Repair a brake portion in the cable. Reduce the load weight. Increase capacities of the motor and inverter. Remedy the earth (ground) fault portion.
Stall prevention Output side earth (ground) fault overcurrent
Output phase failure
Check the wiring. Change the setting of Pr. 251.
External thermal provided for motor overheat protection relay operation or the internally mounted temperature relay in the motor, etc. switches on.
Reduce the load or the number of operation times.
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Function name
Description Appears when the motor overheat
Check point Check the connection between the PTC thermistor switch and
Corrective action
PTC thermistor operation
status is detected for 10s or more by the external PTC thermistor input connected to the terminal AU. Appears when the AC power supply is accidentally connected to R/L1, S/L2, and T/L3 with the high power factor converter connected, or when torque command by the plug-in option is selected using Pr. 804 "Torque command source selection" and no plug-in option is mounted. Also appears if the plug-in optional switch for manufacturer use is switched.
thermal protector. Check the motor for operation under overload. Check that Pr. 184 is enabled. Check that the AC power supply is not connected to the terminals R/L1, S/L2, T/L3 when a high power factor converter or
Reduce the load weight.
Check the Pr. 30 setting and wiring. Check for connection of the plug-in option. Check the Pr. 804 setting. Switch back the plug-in optional switch for manufacturer use.
Option alarm
power regeneration common converter is connected. Check that the plug-in option for torque command setting is connected. Check for a wrong option function setting and operation. Check that the plug-in option
Check the option function setting, etc. Connect the plug-in option securely. Check that the communication cables are connected properly.
Communication option alarm
Appears when a communication line error occurred in the communication option.
E.OP1 to OP3
unit is plugged into the connector securely. Check for a break in the communication cable. Check that the terminal resistor is installed. Check that the option unit is plugged into the connector securely.
Connect the option securely. Take measures against noises if there are devices producing excess electrical noises around the inverter. Fit the communication option to the connector 3.
Appears when a contact fault or the like of the connector between the inverter Option alarm and communication option occurs or when a communication option is fitted to the connector 1 or 2. E. 1 to E. 3
Check for excess electrical noises around the inverter. Check that the communication option is not fitted to the connector 1 or 2.
Parameter storage device alarm (control circuit board) Appears when an error occurred in stored parameters. (EEPROM failure) E.PE Check for too many number of parameter write times. Replace the inverter.
Parameter storage device alarm (main circuit board) Appears when a communication error between the PU and inverter occurred, the communication interval exceeded PU disconnection the permissible time during the RS-485 communication with the PU connecter, or communication errors exceeded the number of retries during the RS-485 communication. E.PUE Check that the FR-DU07 or parameter unit is fitted tightly. Check the Pr. 75 setting. Fit the FR-PU07 or parameter unit securely. Appears when an error occurred in stored parameters. (EEPROM failure) E.PE2 Replace the inverter.
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Function name Retry count excess
Description Appears when the operation was not restarted normally within the set number of retries. Appears when a communication error occurred in the built-in CPU.
Display E.RET
Check point Find the cause of error occurrence. Check for devices producing excess electrical noises around the inverter. Check for a short circuit in the
Corrective action Identify the cause of the error preceding this error indication. Take measures against noises if there are devices producing excess electrical noises around the inverter.
CPU error
Operation panel power supply short circuit, RS-485 terminal power supply short circuit Brake sequence error Appears when a sequence error occurs during use of the brake sequence function. E.MB1 to 7 Appears when the RS-485 terminal power supply or operation panel power supply (PU connector) is shorted. E.CTE
PU connector cable. Check that the RS 485 terminals are connected correctly. Find the cause of error occurrence. Check that the Pr. 374 setting is
Check the PU and cable. Check the connection of the RS-485 terminal.
Check the set parameters and wiring.
Appears when the motor speed exceeds Overspeed occurrence the set over speed level during the encoder feed back control or vector control. E.OS
correct. Check that the number of encoder pulses differ from the actual number of encoder pulses. Check that the Pr. 285 and Pr. 853 settings are correct. Check for sudden load change. E.OSD Check that the number of encoder pulses differ from the actual number of encoder pulses. Check for a break in the cable of the encoder signal. Remedy the break. Use an encoder which meets the specifications. Check the connection. Correct the switch setting of the FR-A7AP. Supply power to the encoder. Check that the encoder specifications are correct. E.ECT Check for a loose connector. Check that the switch setting of the FR-A7AP is correct. Check that power is applied to the encoder. Check that the position Set Pr. 285, Pr. 853 and Pr. 369 correctly. Keep load stable. Set Pr. 374 and Pr. 369 correctly.
Appears when the motor speed is Speed deviation excess detection increased or decreased under the influence of the load, etc. during the vector control and cannot be controlled in accordance with the speed command value.
Appears when the encoder signal is Open cable detection shut off during the orientation control, encoder feed back control or vector control.
Appears when the difference between Position error large the position command and position feedback exceeded the reference during the position control. E.OD
detecting encoder mounting orientation matches the parameter. Check that the load is not large. Check that the Pr. 427 and Pr. 369 settings are correct.
Check the parameters. Reduce the load weight. Set Pr. 427 and Pr. 369 correctly.
Appears when the rotation command of Encoder phase error the inverter differs from the actual motor rotation direction detected from the encoder during offline auto tuning. E.EP
Check for mis-wiring of the encoder cable. Check the Pr. 359 setting.
Perform connection and wiring securely. Set Pr. 359 correctly.
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Function name
Check point
Corrective action
24VDC power supply output short circuit
Appears when the 24VDC power supply output from the PC terminal is shorted.
Check for a short circuit in the PC terminal output.
Remedy the short circuit portion.
Output current detection value excess
Appears when the output current has exceeded the setting of Pr. 150.
Check the settings of Pr. 150, Pr. 151, Pr. 166 and Pr. 167.
Inrush current limit circuit alarm
Change the system to the one Appears when the resistor of the inrush current limit circuit overheats. E.IOH Check that frequent ON/OFF is not repeated. where frequent ON/OFF is not repeated. Replace the inverter.
Appears when a communication error Communication error (inverter) occurred during the RS-485 communication with the RS-485 terminals. E.SER Check the RS-485 terminal wiring. Perform wiring of the RS-485 terminals properly.
Analog input error
Appears when 30mA or more is input or a voltage (7.5V or more) is input with the terminal 2/4 set to current input. E.AIE
Either give a frequency Check the settings of Pr. 73 and command by current input or Pr. 267. set Pr. 73 and Pr. 267 to voltage input.
USB communication error
Appears when communication has broken for the period of time set in Pr. 548. E.USB
Check the USB communication cable.
Change the setting of Pr. 548. Check the USB communication cable.
Opposite rotation deceleration error
Appears when reverse deceleration cannot be performed during the real sensorless vector control due to difference in the motor constant. E.11
Check the setting of Pr. 71. Check that both the offline and online auto tunings were performed.
Check the Pr. 71 setting. Perform offline auto tuning, then enable online auto tuning.
Internal error
circuit Appears when an internal circuit error occurred.
Replace the inverter.
If protective functions of E.ILF, E.PTC, E.PE2, E.PE, E.OD, E.CDO, E.IOH, E.SER, E.AIE, E.USB are activated when using the FR-PU04, "Fault 14" is displayed. Also when the alarm history is checked on the FR-PU04, the display is "E.14".
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8.8 Exercising with the Training Kit
There is a training kit (the FR-A demonstration machine) available, which is to confirm motor performance and inverter controllability/function in the operating condition that a motor is connected to an inverter and a load. Use the training kit to obtain experiential knowledge in the said contents.
8.8.1 Test operations
The following items can be confirmed with the FR-A demonstration machine. (1) Difference in generated torque between low-speed operations by the advanced magnetic flux vector control, real sensorless vector control, and V/F control. (2) Acceleration/deceleration performance in accordance with the load weight (3) Inverter operation, monitor (for terminal I/O status, troubleshooting functions), etc. by the interactive parameter unit (4) Output terminals assignment function (5) Life check
8.8.2 Configuration of the demonstration machine
Demonstration machine body
R Power supply 1 100V NFB Tr MC1 R1 S,T
Operation panel
Instantaneous power failure switch
Speed meter
Frequency setting
Compensation input Powder brake MC2 Load ON/OFF DA Load torque adjustment VR
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8.8.3 Description of the demonstration machine
The demonstration machine consists of an operation panel and a power supply load box. (1) Operation panel The operation panel is as shown below.
FR-A実習機 (FR-A demonstration machine)
FM端子出力 端子出力 (FM terminal output) (AM terminal output) 出力端子状態 (Output terminal status)
出力切換 (Switch output)
高速RH (High 中速RM (Middle 低速RL (Low speed RL) speed RH) speed RM)
周波数設定 (Frequency setting)
出力停止 補正入力 第2加減速 (Second (Compensation input) (Output stop) acceleration/deceleration)
正転STF (Forward STF)
逆転STR 瞬停 (Reverse STR) (Instantaneous power failure)
Fig. 8.1 Operation panel 1) FM 端子出力(FM terminal output)............ Displays output frequency (pulse output) from the inverter. 2) AM 端子出力(AM terminal output) ........... Displays output frequency (analog output) from the inverter. 3) 出力切換(Switch output)........................... Switches the terminal enabled for inverter output frequency between FM 端子出力(FM terminal output) and AM 端子出力(AM terminal output). 4) RUN ............................................................. Turns on when output frequency becomes higher than the starting frequency, indicating that the inverter is in operation. 5) SU................................................................. Turns on when output frequency enters in the range of 10% of the set frequency, indicating that frequency increase has completed. 6) IPF................................................................ Turns on when the instantaneous power failure function or the undervoltage protective function is activated, indicating that an instantaneous power failure occurred.
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7) OL ................................................................. Turns on when the current limit function activated the stall prevention function, indicating an overlord alarm. 8) FU ................................................................. Turns on when output frequency reaches or exceeds the optionally set detection frequency, indicating a frequency detection. 9) 周波数設定(Frequency setting) ...............Allows the set frequency to be output with analog voltage. 10) 補正入力(Compensation input) ............ Allows extra voltage to be added to the analog voltage set with 周波数設定(Frequency setting). 11) 高速(High speed)..................................... Selects "高速(High speed)" from the multi-speed setting. RH Note that up to seven different speeds are available in combination with "中速(Middle speed)" and "低速(Low speed)". 12) 中速(Middle speed) .................................Selects "中速(Middle speed)" from the multi-speed setting. R Note that up to seven different speeds are available in combination with " 高 速 (High speed)" and " 低 速 (Low speed)". 13) 低速(Low speed)...................................... Selects "低速(Low speed)" from the multi-speed setting. RL Note that up to seven different speeds are available in combination with "高速(High speed)" and "中速(Middle speed)". 14) 出力停止(Output stop) ............................Stops the inverter output. MRS 15) 第2加減速(Second acceleration/deceleration) RT .............................................. Selects second acceleration/deceleration time. 16) 正転(Forward)...................................... Forward rotation start signal STF 17) 逆転(Reverse) ...................................... Reverse rotation start signal STR 18) 瞬停(Instantaneous power failure) ........Shuts off the power supply for the inverter. (2) Power supply load box The power supply load box is as shown below.
負荷トルク モータ速度 (Load torque) (Motor speed) 負荷装置(Load unit) 過熱(Overheat)
サーマルリセット (Thermal reset)
負荷設定 負荷ON/OFF (Load setting) (Load ON/OFF)
Fig. 8.2 Power supply load box
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1) 負荷トルク(Load torque) ......................... Indicates the load torque applied to the motor. 2) モータ速度(Motor speed) ........................ Indicates the motor speed. 3) 負荷設定(Load setting)............................. Sets the load applied to the motor. 4) 負荷 ON/OFF(Load ON/OFF) ................. A switch to turn on and off the load on the motor. 5) 過熱(Overheat) .......................................... Turns on when overheat is generated on the motor's load. 6) サーマルリセット(Thermal reset) ............. Resets the thermal relay when overheat is generated on the motor's load. 7) 電源 NF(Power supply noise filter) ......... Power supply noise filter for the demonstration machine 8) Outlet ........................................................... 100VAC outlet for external output 9) Connector 1 ................................................ 100VAC input connector 10) Connector 2 ............................................... Connector for motor output and load (3) Precautions for use (1) Set the maximum frequency to 60Hz. (2) Set the acceleration/deceleration time to one second or longer. Technically, frequency can be set higher than 60Hz and acceleration time can be set shorter than 1 second. However, setting those values may damage the machine due to the use of the powder brake, pilot generator (PG) and timing belt.
(3) Do not leave the demonstration machine for a long time with the 負荷 ON/OFF(Load ON/OFF) switch set to ON and the 負荷設定(Load setting) VR high.
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8.8.4 How to use the operation panel FR-DU07
(1) Basic operation
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(2) All clear
• Set "1" in "ALLC parameter clear" to initialize all parameters. (Parameters are not cleared if "1" is set in
Pr. 77 "Parameter write selection".)
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(3) Parameter copy Parameter settings can be copied to multiple inverters.
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8.8.5 How to use the parameter unit FR-PU07
Appearance and names of the FR-PU07
POWER lamp Lit when the power turns on. Monitor
Liquid crystal display (16 characters&drcross4 lines, with backlight) Interactive parameter setting Help function Troubleshooting guidance Monitor (frequency, current, power, etc.)
Connection connector Connector to be connected to the inverter. Connect directly to the PU connector of the inverter.
60.00Hz STF FW D PU
ALARM lamp
Lit to indicate an inverter alarm occurrence.
Cable connection connector Connect using the connection cable (FR-CB2 )
Operation keys
[The squares below indicate the keys on the parameter unit.] (1) Parameter clear PU FUNC Select Pr. Clear READ Select Clear All
↑Press the up-down key. ↑Press the up-down key.
(2) Operation PU operation → PU Stop → STOP Jog operation → PU PU SHIFT ↑e.g.60
↓LCD flickers to indicate the completion of writing. Enter the target frequency WRITE FWD or REV WRITE FWD or REV
Enter the target frequency ↑e.g .1 0
Cancel Jog operation
External operation → EXT Set the frequency setting potentiometer provided on the demonstration machine panel, and turn on the switch for forward rotation or reverse rotation.
Press the up-down key.
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(3) Monitor MON (4) Parameter read PU PrSET
DC Peak V
READ , press the WRITE key.
To display the target data before any other data after pressing MON Enter the target parameter No. ↑e.g. 9 (5) Parameter setting change Overwrite the read parameter value by the target parameter value ↑e.g. 1.3 (6) Frequency meter calibration 1) Using the PU, perform operation in 60Hz. 2) PU PrSET 9 0 0 READ READ
3) Press the up-down keys ↑ and ↓ to move the reading of the frequency meter. Set the reading to the command value (60Hz), and press WRITE . (7) Parameter copy Setting values of up to three inverters can be copied. Read parameters from the source inverter. PU FUNC FRCpy set READ Copy area1 Press the up-down key. Example READ
The set parameter value of individual inverters can be copied to each of areas 1, 2, and 3.
Name example: 112 to 223 ヨミダシ READ 112 2 1 2 READ 2 2 2 READ 2 2 3 WRITE WRITE
Up-down key Up-down key Up-down key
Write to the target inverter. PU FUNC FRCpy set READ Copy area1
Up-down key
Example READ
Name example Write VFD
Up-down key
Reset the inverter
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(8) User group function This function allows only setting-required parameters to be displayed. Among all parameters, max. 16 parameters can be registered.
Register Example PU PrSET 8
Pr. 8
Example 5 WRITE
5 sec.
Delete PU PrSET User List READ Select the parameter to be deleted.
Continue the same process for another parameter.
Press the up-down key
Press the up-down key
Continue the same process for another parameter.
Confirm registration PrSET User List READ
Press the up-down key
To display, read and write only registered parameters, preset "1" in Pr. 160. PU PrSET 160 READ
Pr. 160
Parameter numbers displayed change from all parameter numbers to the parameter numbers that are registered in the user group. To reset this setting, change the set value in Pr. 160 from "1" to "0". PU PrSET 160 READ 0 WRITE
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8.8.6 Basic tasks before starting up an inverter
(1) Clear all parameters (when using an inverter that has previously been used) (2) Check input and output signals (sequence check) Use the FUNC function of the PU to check that signals are input or output. PU FUNC Selectop READ
Press the up-down key
(3) Set the basic parameters Examples: 1) Maximum frequency (Pr. 1) PU PU PU PrSET PrSET PrSET 1 9 READ READ 6 1 0 . 6 WRITE 3 0 WRITE WRITE 2) Electronic thermal O/L relay (Pr. 9) 3) Frequency setting signal gains (Pr. 125) 125 READ
↑50 in Tokyo
(4) Calibrate the frequency meter (5) Select an operation mode In Pr. 79, select one of the followings: only external operation, only PU operation, both external and PU operations. (External operation and PU operation can be switched over with factory setting.) The key here is to select an operation mode after parameters are set for each function.
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8.8.7 Operation of inverter (principle-related matter)
(1) Confirming the behavior of inverter DC voltage (V/F control) Confirm how the DC voltage in the inverter behaves in the following conditions. Use a monitor function to read the values. Operating condition 1) When an inverter is at a stop 2) During operation at 60Hz DC voltage Vdc (V) Reference value 313 303
(without loads) 3) During operation at 60Hz (with 100% load) Operation procedure: PU FUNC モニタ READ Vdc READ 290
Press the up-down key. (2) Regenerative overvoltage Check how the DC voltage behaves in the condition that the motor decelerates to a stop from the speed of 60Hz in the deceleration time of 0.5 seconds. (Display the peak Vdc on the monitor.) DC voltage Vdc(V) 1) Without loads 2) With 100% load Operation procedure: PU FUNC モニタ READ DC Peak V READ
Press the up-down key.
After the operation is finished, set the deceleration time back to the original value. (3) Confirming output voltage (V/F control) Confirm output voltage with the torque boost (Pr. 0) set to 6%. Use a monitor function to read output voltage. Check the relation between the logical value and the monitored value. PU SHIFT Vモニタ MON SHIFT
Calculated value … Calculated output voltage value to the output frequency Monitored value 1) ........... When "9999" is set in Pr. 19 Monitored value 2) ........... When the value of power supply voltage is set in Pr. 19 (output voltage is 200V during operation at 60Hz) PU PrSET 19 READ 200 WRITE
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Output frequency (Hz)
Calculated value V (Monitored value 2))
Monitored value 1) (V)
Monitored value 2) (V)
6 10 20 30 50 60
Logical calculation value V = [(a-b)/60] F + b (v)
Output voltage
6% b[V] 0
Output frequency F
For parameters, refer to the catalog of FREQROL-A700.
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8.8.8 Torque boost function and real sensorless vector function (Confirming operations of V/F control and real sensorless vector control)
(1) Changes in current and voltage in accordance with the V/F control and torque boost setting value Calculate output current and output voltage when the setting value of the torque boost is changed. 1) Multi-speed operation in various frequencies Conditions: V/F control
F(HZ) Voltage (V) Pr0=6 Current (A) No load V/F Voltage (V) Pr0=3 Current (A) 0 V/F V2 A2 6
Standard torque boost
10 20 30
Pr. 14=0
40 50
(Rated torque load)
60 Abbreviation V1 A1
Voltage (V) 90% Pr0=6 Current (A) load V/F Pr60=4
Voltage (V) No Pr0=6 load Current (A)
2.0 1.5 1.0
0.5 0
6 10 20 30 Hz 40 50 60
20 Hz
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2) PU operation at 2Hz Torque boost setting 6% 30% Load 0 100 0 100 Output current (A) Output voltage (V)
<Confirming generated torque> 1) Increase the load magnitude with torque boost 6% until the motor stops. Stop the inverter when the motor stopped. 2) Set the torque boost to 30% and start the inverter. Check the motor rotation. 3) Increase the load, and confirm the current value of when the motor has stopped. (2) Real sensorless vector control 1) Record the load torque value (percentage of the meter) of when the motor has stopped in the above torque boost 30% operation. 2) Perform auto tuning in the real sensorless vector control. (Refer to the following.) Confirm the followings in the operation of the real sensorless vector control mode.
• Operation frequency 2Hz
Load (%) 0 100 <Confirming generated torque> Provide the motor with the load that stopped the motor in the torque boost 30% operation. Check the motor rotation in this case. Output current (A) Output voltage (V) Output frequency (Hz)
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How to perform auto tuning in the real sensorless vector control
1) Parameter setting -1) Motor type setting -2) Motor setting -3) Control method -4) Torque limit Pr. 71=3 (for a standard motor) Pr.80=0.4(kW) Pr.81=4(P) Pr. 800= 10 (for speed control) Pr.810=0、Pr.22=200(%)
-5) Tuning method setting Pr. 83=200(V), Pr. 84=60(Hz), Pr. 96=101. (tuning with rotation) Setting "1" in Pr .96 allows tuning without rotation. -6) Electronic thermal relay settingPr.9=1.3(A) 2) Tuning operation Press MON . -1) In the PU operation mode, press FWD or REV to start tuning. After the tuning completes, the display shows TUNE Completed 103 or 3. Press STOP to terminate the operation. -2) In the external operation mode, turn on the forward rotation switch or reverse rotation switch provided on the operation panel. After completed, turn off the forward rotation switch or reverse rotation switch. 3) Exiting the real sensorless vector control (Returning to the V/F control) Set "9999" in Pr. 80 and Pr. 81. For parameters, refer to the catalog of FREQROL-A700.
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8.8.9 Inverter-protection-related matter (V/F control)
(1) Electronic thermal relay (motor overheat protection) 1) Operate the electric thermal relay Set 0.6A in Pr. 9 (electric thermal relay) and perform operation at 6Hz. A trip will occur in 20 to 30 seconds. Confirm Hz, I and V of when a trip is occurred by pressing MON … SHIFT … SHIFT . 2) Set "1" in Pr. 76 (alarm code output selection) and make a trip occur. Check the result. IPF and FU of the demonstration machine turn on. after this exercise. 3) Use the retry function Set Pr. 67 to three times and Pr. 68 to 5 seconds, and then check a result of pressing FWD . Perform retry. 4) During operation, check the operation status of the electric thermal relay. Set "10" in Pr. 52 (monitor output signal selection) and press FWD . Check the display status on the monitor. Hz A % Pu 5) Check the pre-alarm function. In addition to step 4, set "8" in Pr. 191 (output terminal function selection) and make the lamp SU turn on. 6) Reset signal The followings are how to enable external reset signals during abnormal operation as well as disable the signals when they are input during normal operation.
→ Set Pr. 76 back to "0"
• Use the reset switch on the operation panel to use reset signals. • Confirm that "15" is set in Pr. 75 (reset selection).
After the above exercise, set Pr. 9 (electric thermal relay) back to 1.3A. (2) Operation of the stall prevention function (V/F control) Check the operation status at motor start in the condition that 35% is set in Pr. 22 (stall prevention activation level) and 0.5 seconds is set as acceleration time. Rotate the motor with 100% load at 60Hz. --OL appears on the PR display. Check the motor rotation status.-After the operation is finished, set the acceleration time back to the original value. For parameters, refer to the catalog of FREQROL-A700.
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8.8.10 Operation-related matter (V/F control)
(1) Confirm how many seconds it takes to reach 30Hz with acceleration time set to 5 seconds. sec. Note that the setting of Pr. 20 (acceleration/deceleration reference frequency) is relevant. (2) Perform multi-speed operation of seven speeds. Set any, different frequency in Pr. 4 to 6 and Pr. 24 to 27, and perform the operation. (Note that the demonstration machine does not have terminals for multi-speed operation of 15 speeds.) Set "1" in Pr. 28 to make auxiliary input variable. (3) Use the parameter unit (PU) to start a motor (forward or reverse rotation). Adjust the frequency setting potentiometer on the operation panel or set multi-speed operation mode to make frequency settings. -- Set "4" in Pr. 79 (operation mode selection). -(4) To make the electric brake activate smoothly, inverter output must be turned off immediately after the start signal is turned off. Use Pr. 250 (stop selection) to realize this. Perform the following and check the resulting operation. -- Set Pr. 250 to 0.1(S). --- Alternatively, set Pr. 250 to 0(S). -(5) Check the operation of DC control. Set "3" and "10" in Pr. 10, "0.5" and "5" in Pr. 11, and "0" and "4" in Pr .12.
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(6) Check detected output frequency. Set Pr. 13, 41 and 42.
33Hz Pr.41=10%
Rotation frequency (e.g. 30Hz) Output frequency
Pr.13 =0.5Hz 27Hz Pr.42=6Hz
(7) Change the monitor display and frequency setting to the machine speed. Example: Change Pr. 37 from "0" to "50" or change Pr. 144 from "4" to "104". For parameters, refer to the catalog of FREQROL-A700.
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8.8.11 Safety-measure-related functions
(1) [Overspeed prevention] by applying a limit to the maximum output frequency 1) Check the set value of the maximum frequency setting (Pr. 1). 2) Make a gain frequency setting for frequency setting signals (e.g. Pr. 125).
Set a gain so that the output frequency is 65Hz when the frequency setting potentiometer is
turned to max. When Pr. 125 is set to 65Hz. Remark: Gain can be adjusted in C4 (Pr. 903). The parentheses indicate the procedures for the FR-PU07. Pr. 903 (FR-PU07) PU PrSET 903 READ READ 6 5 Turn the frequency setting potentiometer to max. C.4 (operation panel FR-DU07)
65 Hz
Turn the dial
Turn the frequency setting potentiometer to max.
(2) [Minimum speed guarantee] by applying a limit to the minimum output frequency 1) Use the minimum frequency setting (Pr. 2).
• Check the running frequency when turning the start signal on with the minimum frequency set to
10Hz. Set Pr. 7 (acceleration time) to approximately 20 seconds for this exercise. (3) [Overrun prevention, drop prevention] by the timing that the electromagnetic brake activates 1) Output frequency detection (Pr. 42, Pr. 43) 2) Brake sequence function (Pr. 278 to 285) (4) [Incorrect input prevention] 1) Reset input selection (Pr. 75) 2) Reverse rotation prevention (Pr. 78) (5) [Misoperation prevention] 1) Disconnected PU detection, PU stop selection (Pr. 75) 2) PU operation interlock, operation mode external signal switching (Pr. 79)
• Set "0" in Pr.76 and Pr.191 so that the lamp SU turns on during PU operation. (RUN function
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(6) [Resonance operation prevention] 1) Frequency jump (Pr. 31 to 36) (7) [Automatic restart after instantaneous power failure] Set "0" in Pr. 57 and Pr. 162, and "6" in Pr. 183. Turn on the second acceleration/deceleration (CS function) switch. Set the operation mode to the external operation mode, and make an instantaneous power failure occur. For parameters, refer to the catalog of FREQROL-A700.
8.8.12 Life check of inverter parts (FREQROL-A700)
(1) Measuring a capacity of the main circuit capacitor and displaying a service life 1. Confirm that the motor is connected and at a stop. 2. Set "1" in Pr. 259. 3. Turn off the power supply. Measure a capacity of the capacitor at this time. 4. Confirm that the POWER lamp has been turned off, and then turn the power supply on again. 5. Confirm that "3" (measurement completion) is set in Pr. 259, and then confirm Pr. 258 for life display. (2) Confirm Pr. 256 for life display of the inrush current control circuit and Pr. 257 for life display of the control circuit capacitor. For parameters, refer to the catalog of FREQROL-A700 series.
8.8.13 Selection-related matter
(1) Select the inverter capacity most suitable for the parallel operation shown below.
200V 60Hz Power supply Inverter
2.2kw 4P Rated current 10A 2.2kw 4P
Inverter FR-A720-
(Note) The rated motor current is 10A.
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When exported from Japan, this manual does not require application to the Ministry of Economy, Trade and Industry for service transaction permission.
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