Omron VARISPEED G7 -, Instruction Manual

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Troubleshooting
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23
If the Ground Fault Interrupter Operates When the Inverter is Run
The Inverter performs internal switching, so there is a certain amount of leakage current. This may cause the
ground fault interrupter to operate and cut off the power supply. Change to a ground fault interrupter with a
high leakage detection level (i.e., a sensitivity current of 200 mA or greater per Unit, with an operating time of
0.1 s or more), or one that incorporates high frequency countermeasures (i.e., one designed for use with Invert-
ers). It will also help to some extent to change the Inverter's Carrier Frequency Selection (C6-02) to lower the
carrier frequency. In addition, remember that the leakage current increases as the cable is lengthened.
If There is Mechanical Oscillation
Use the following information when there is mechanical oscillation.
The machinery is making unusual sounds.
The following causes are possible.
There may be resonance between the mechanical system's characteristic frequency and the
carrier frequency.
If the motor is running with no problems and the machinery is oscillating with a high-pitched whine, it may
indicate that this is occurring. To prevent this type of resonance, adjust the carrier frequency with constants
C6-02 to C6-05.
There may be resonance between a machine's characteristic frequency and the output fre-
quency of the Inverter.
To prevent this from occurring, either use the jump frequency functions in constants d3-01 to d3-04 or install
rubber padding on the motor base to reduce oscillation.
Oscillation and hunting are occurring with open-loop vector control 1.
The gain adjustment may be insufficient. Reset the gain to a more effective level by adjusting constants C4-02
(torque compensation time constant), C2-01 (S-curve Characteristic Time at Acceleration Start), and C3-02
(Slip Compensation Primary Delay Time) in order. Lower the gain setting and raise the primary delay time
setting.
Vector control will not perform if autotuning has not been performed. Perform autotuning separately for the
motor, or set the motor constants through calculations. Alternatively, change the control method selection (A1-
02) to V/f control (0 or 1).
Oscillation and hunting are occurring with V/f control.
The gain adjustment may be insufficient. Reset the gain to a more effective level by adjusting constants C4-02
(Torque Compensation Primary Delay Time Constant), N1-02 (Hunting Prevention Gain), and C3-02 (Slip
Compensation Primary Delay Time) in order. Lower the gain setting and raise the primary delay time setting.
Oscillation and hunting are occurring with V/f w/PG control.
The gain adjustment may be insufficient. Adjust the various types of speed control loop (ASR) gain.
If the oscillation cannot be eliminated in this way, set the hunting prevention selection (constant N1-01) to 0
(disabled) and then try adjusting the gain again.