Dear Expert

Recently one of the customer facing a problem with Over voltage trippin during ON command for pump application

Whenever ON command being issued , VFD is tripping on " Over Voltage"

Customer has replace the VFD with spare VFD but same issue.

Also customer has replace VFD with running VFD - No tripping ( CU is same, programe is same).

What could be the issue,."?

G120,30 Kw, CU240E-2DP

I've gotten this problem before. When the drive tries to slow down a large amount of inertia too fast you can pump the voltage on the capacitors.

Try increasing the deceleration time.

The drive is tripping with over Voltage as the run command is provided, even before the motor starts to move.

This is a short circuit in the cable assembly between the drive and the motor. The screen will be connected to one of the phase cables.

This makes the screen of the cable into a capacitor which feeds back into the DC link, via the misconnected power cable, raising the voltage, and tripping the drive.

This may be caused by cable damage or miss connection.  My latest incident was a 'chap' cut the motor power cable with an angle grinder, then covered the cable in the duct. The cable in a steel works was long, and it took some persuading the client that the cable had to be replaced..