Cause : Over voltage comes when the inverter turns off its output if the DC voltage of the main circuit increases higher than 400 V when the motor decelerates. This fault can also occur due to a surge voltage generated at the power supply system.

1. Increase the Decel time.
2. Regenerative load is at the inverter output.
3. Use Dynamic Brake Unit.
4. Line voltage is too high.
5. Check whether line voltage exceeds its rating.