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#181987 - 11/14/08 12:59 PM VFD BURNING OUT MOTOR BEARING  
GETELECTRIC  Offline
Member
Joined: Oct 2003
Posts: 172
toronto canada
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?


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#181990 - 11/14/08 03:04 PM Re: VFD BURNING OUT MOTOR BEARING [Re: GETELECTRIC]  
gfretwell  Offline


Member
Joined: Jul 2004
Posts: 9,122
Estero,Fl,usa
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.


Greg Fretwell

#181994 - 11/14/08 09:26 PM Re: VFD BURNING OUT MOTOR BEARING [Re: gfretwell]  
twh  Offline
Member
Joined: Mar 2004
Posts: 919
Regina, Sask.
That isn't logical.

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


#181995 - 11/14/08 10:12 PM Re: VFD BURNING OUT MOTOR BEARING [Re: GETELECTRIC]  
Albert  Offline
Member
Joined: Aug 2006
Posts: 76
Falls Church, VA
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.


#181996 - 11/14/08 10:22 PM Re: VFD BURNING OUT MOTOR BEARING [Re: GETELECTRIC]  
Albert  Offline
Member
Joined: Aug 2006
Posts: 76
Falls Church, VA


#181997 - 11/14/08 11:28 PM Re: VFD BURNING OUT MOTOR BEARING [Re: Albert]  
HotLine1  Offline


Member
Joined: Apr 2002
Posts: 6,872
Brick, NJ USA
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.



John

#181999 - 11/14/08 11:58 PM Re: VFD BURNING OUT MOTOR BEARING [Re: HotLine1]  
gfretwell  Offline


Member
Joined: Jul 2004
Posts: 9,122
Estero,Fl,usa
interesting stuff. Surprised me.


Greg Fretwell

#182000 - 11/15/08 12:36 AM Re: VFD BURNING OUT MOTOR BEARING [Re: gfretwell]  
leland  Offline
Member
Joined: Aug 2007
Posts: 853
Lowell area, Ma. USA
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.


#182009 - 11/15/08 02:41 PM Re: VFD BURNING OUT MOTOR BEARING [Re: leland]  
gfretwell  Offline


Member
Joined: Jul 2004
Posts: 9,122
Estero,Fl,usa
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.


Greg Fretwell

#182011 - 11/15/08 08:50 PM Re: VFD BURNING OUT MOTOR BEARING [Re: leland]  
renosteinke  Offline
Cat Servant
Member
Joined: Jan 2005
Posts: 5,316
Blue Collar Country
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.


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