Cause : Overvoltage comes when DC bus voltage has exceeded the peak level or the maximum continuous level for 15 seconds.

1. Increase deceleration ramp (Pr 0.04).
2. Decrease braking resistor value (staying above the minimum value).
3. Check nominal AC supply level.
4. Check for supply disturbances which could cause the DC bus to rise – voltage overshoot after supply recovery from a notch induced by DC drives.
5. Check motor insulation.