Cause : Regenerative overvoltage trip during constant speed comes when the inverter's internal main circuit DC voltage to reach or exceed the specified value, the protection circuit is activated to stop the inverter output. The circuit may also be activated by a surge voltage produced in the power supply system.

1. Check for sudden load change.
2. Check that the Pr.22 Stall prevention operation level is not set to the no load current or lower.
3. Check if the stall prevention operation is frequently activated in an application with a large load inertia.
4. Check that acceleration/deceleration time is not too short.