Troubleshooting
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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
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 parameters
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 parameters d3-01 to d3-04 or install
rubber padding on the motor base to reduce oscillation.
Oscillation and hunting are occurring.
The gain adjustment may be insufficient. Reset the gain to a more effective level by adjusting parameters C4-
02 (Torque Compensation Primary Delay Time parameter) and N1-02 (Hunting Prevention Gain) in order.
Lower the gain setting and raise the primary delay time setting.
Oscillation and hunting are occurring with PI control.
If there is oscillation or hunting during PI control, check the oscillation cycle and individually adjust P and I
parameters. (Refer to page 6-196)
If the Motor Rotates Even When Inverter Output is Stopped
If the motor rotates even when the Inverter output is stopped, the DC injection braking is insufficient. If the
motor continues operating at low speed, without completely stopping and after a deceleration stop has been
executed, it means that the DC injection braking is not decelerating enough. Adjust the DC injection braking
as follows:
•
Increase the parameter b2-02 (DC Injection Braking Current) setting.
•
Increase the parameter b2-04 (DC Injection Braking (initial excitation) Time at Stop) setting.
