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#181987 - 11/14/08 08:59 AM VFD BURNING OUT MOTOR BEARING
GETELECTRIC Offline
Member
Registered: 10/22/03
Posts: 172
Loc: 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 11:04 AM Re: VFD BURNING OUT MOTOR BEARING [Re: GETELECTRIC]
gfretwell Offline


Member
Registered: 07/20/04
Posts: 9039
Loc: 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.
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Greg Fretwell
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#181994 - 11/14/08 05:26 PM Re: VFD BURNING OUT MOTOR BEARING [Re: gfretwell]
twh Offline
Member
Registered: 03/11/04
Posts: 901
Loc: Regina, Sask.
That isn't logical.

However, blaming the competition for everything from bearings to bad weather is quite normal.
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#181995 - 11/14/08 06:12 PM Re: VFD BURNING OUT MOTOR BEARING [Re: GETELECTRIC]
Albert Offline
Member
Registered: 08/16/06
Posts: 76
Loc: 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.
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#181996 - 11/14/08 06:22 PM Re: VFD BURNING OUT MOTOR BEARING [Re: GETELECTRIC]
Albert Offline
Member
Registered: 08/16/06
Posts: 76
Loc: Falls Church, VA
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#181997 - 11/14/08 07:28 PM Re: VFD BURNING OUT MOTOR BEARING [Re: Albert]
HotLine1 Offline


Member
Registered: 04/03/02
Posts: 6778
Loc: 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.

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John
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#181999 - 11/14/08 07:58 PM Re: VFD BURNING OUT MOTOR BEARING [Re: HotLine1]
gfretwell Offline


Member
Registered: 07/20/04
Posts: 9039
Loc: Estero,Fl,usa
interesting stuff. Surprised me.
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Greg Fretwell
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#182000 - 11/14/08 08:36 PM Re: VFD BURNING OUT MOTOR BEARING [Re: gfretwell]
leland Offline
Member
Registered: 08/20/07
Posts: 853
Loc: 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.
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#182009 - 11/15/08 10:41 AM Re: VFD BURNING OUT MOTOR BEARING [Re: leland]
gfretwell Offline


Member
Registered: 07/20/04
Posts: 9039
Loc: 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
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#182011 - 11/15/08 04:50 PM Re: VFD BURNING OUT MOTOR BEARING [Re: leland]
renosteinke Offline
Cat Servant
Member
Registered: 01/22/05
Posts: 5316
Loc: 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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