Troubleshooting
7-19
îš‹ If peripheral devices like PLCs or other are influenced
by the starting or running inverter
If electrical noise is generated by Inverter perform the following countermeasures:
• Change the Inverter's Carrier Frequency Selection (C6-02) to lower the carrier frequency. This will help to
reduce the amount of transistor switching noise.
• Install an Input Noise Filter at the Inverter's power input terminals.
• Install an Output Noise Filter at the Inverter's motor terminals.
• Use shielded cables or a conduit. Metal shields electrical noise.
• Separate main circuit wiring from control circuit wiring.
îš‹ If the Earth Leakage Breaker Operates when a RUN Command is Input
The Inverter’s output is pulse modulated, i.e. the output voltage consists of high frequency pulses (PWM).
This high frequency signal causes a certain amount of leakage current which may cause the earth leakage
breaker 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 higher, with an operating time of 0.1 s or more), or one
that incorporates high frequencies countermeasures (i.e., one designed for use with Inverters). It will also help
to some extent to lower the Inverter's Carrier Frequency Selection (C6-02). In addition, remember that the
leakage current increases as the cable is lengthened.
îš‹ If There is Mechanical Oscillation
îš„The machinery is making unusual sounds.
There may be resonance between the mechanical system's natural frequency and the carrier
frequency.
This is characterized by the motor running with no noise generation, but the machinery vibrates with a high-
pitched whine. To prevent this type of resonance, adjust the carrier frequency with parameters C6-02 to
C6-05.
There may be resonance between a mechanical system’s natural frequency and the output fre-
quency of the Inverter.
To prevent this resonance frequency use the Jump Frequency Function in parameters d3-, or have the
driven motor and load balanced to reduce vibration.
îš„Oscillation and hunting occur.
The torque compensation parameter settings may be incorrect for the machine. Adjust parameters C4-01
(Torque Compensation Gain) and C4-02 (Torque Compensation Delay Time). Decrease C4-01 carefully in
steps of 0.05 and/or increase C4-02.
Furthermore the Hunting Prevention Gain (n1-02) can be increased if the problems occur in light load condi-
tions and the Slip Compensation Delay Time (C3-02) can be decreased.
îš„Oscillation and hunting occur 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 6-87, Using PI Control).
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