Electrician Talk banner

Funny voltage on load side of VFD

7740 Views 5 Replies 4 Participants Last post by  Big John
I need some assistance diagnosing a problem on a Delta drive on our saw.

We were getting an over load fault on our drive and we found some bad bearings on the shaft. But even after we disconnected the belt and there is no load we were still getting the same fault.

It is a 6 lead part winding motor and I rang it out and all the windings had continuity were it should and none were going to ground so I think the motor is good

I pulled the motor leads off the drive and checked voltage and I am getting 119 volts to ground on my A and C phase but only 63 volts to ground on the B phase. Phase to phase I get 198 volts from A to C but only 165 volts from my B phase. This is at 58 hertz. Could I have a problem with the drive?

The incoming voltage is 218 volts three phase. And the drive is rated at 230 volts three phase.
1 - 2 of 6 Posts
Maybe a stupid question but did you try spinning the motor by hand once uncoupled?
Yes. The motor spins fine.
1 - 2 of 6 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.