We have recently installed vfd's in exixting circuits and now one of the motors has burned out and they are blaming our VFD. The vfd s are not even programmed to do any control as of yet just off and on.
Can it be the VFD the controls company is saying that our VFD's are causing a voltage across the bearings?

What is the motor driving? Is there any chance voltage is getting transferred to the motor shaft?
I really don't see this being a VFD problem.

That isn't logical.

However, blaming the competition for everything from bearings to bad weather is quite normal.

I vaguely remember reading something about this in a trade magazine (maybe EC&M). As I recall, it has to do with current spikes from the VFD's output inducing a voltage on the motor shaft via the windings, and the current arcing across the bearings and burning them.

Here's a paper on the topic:
http://www.aemc.fr/index.php?page=t...mp;file=200710291112-BearingCurrents.pdf

Thanks Albert

Another timely subject! Got a call this afternoon regarding a sewage lift station pump/VFD/panel meltdown, on a 'fairly new' install. That's Mondays problem child. This PDF may be interesting reading.

interesting stuff. Surprised me.

I recall this conversation not too long ago.

Wait For RENO Or Frenchelectrician. I believe they have the skinny on it.

Yes it did have something to do with induction.

I think the real answer is the EMI filter mentioned in the article. I would be surprised that a decent VFD wouldn't have that, just for FCC compliance.

Thanks for the vote of confidence ... but the issue is beyond my experience.

I've only seen bearings damaged by current flow, either through a fault condition, or when someone did some welding on the machine.