Intermittent Vibration in motor connect to VFD
Intermittent Vibration in motor connect to VFD
(OP)
I have a VFD connected to a small motor (5 HP). The motor operates fine when its not connected to the VFD, but when it operates connected to the VFD (and with no load) it intermittently vibrates and it has a frame-to-ground voltage of about 50 Volts. What could be the problem, and how do I fix it?





RE: Intermittent Vibration in motor connect to VFD
"An 'expert' is someone who has made every possible mistake in a very narrow field of study." -- Edward Teller
RE: Intermittent Vibration in motor connect to VFD
RE: Intermittent Vibration in motor connect to VFD
Please describe more fully what and how you are measuring.
RE: Intermittent Vibration in motor connect to VFD
As DickDV, I'm suspicious of your 50V reading if the motor is well grounded.
"An 'expert' is someone who has made every possible mistake in a very narrow field of study." -- Edward Teller
RE: Intermittent Vibration in motor connect to VFD
I also tested other motors and I keep having the same issue.
RE: Intermittent Vibration in motor connect to VFD
RE: Intermittent Vibration in motor connect to VFD
If it goes away, I would attribute it to some minor resonance in the motor and not worry about it any further. If it does not go away, I would consider it a mechanical issue. First thing would be to check the dynamic balance of the rotor.
50V on an ungrounded motor frame is no concern at all. I'm surprised it isn't more.
RE: Intermittent Vibration in motor connect to VFD
I suspect the 50V measured could be a different issue to the vibration.