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Motor Questions

Motor Questions

Motor Questions

(OP)
I have a couple of IEEE 841 motor questions as below,
1. Is it necessary to insulate both DE and NDE bearing for Non VFD motor?
2. Motor space heater and RTD terminals are located in the same terminal box with a barriar in between.

Any comments on the above statements? Thanks in advance.

 

RE: Motor Questions

Quote:

I have a couple of IEEE 841 motor questions as below,
1. Is it necessary to insulate both DE and NDE bearing for Non VFD motor?
To the best of my knowledge, IEEE841 does not require insulation of either bearing. And in this size range, for non-vfd motors, insulated bearing is not required imo.

Quote:

2. Motor space heater and RTD terminals are located in the same terminal box with a barriar in between.
I am used to seeing power and instrument cables routed separately for larger motors (we don't have rtd's on our small motors).  But I didn't see anything about that in IEEE 841.  
 

=====================================
(2B)+(2B)'  ?

RE: Motor Questions

(OP)
Agree. These seem to be weired statements that need to corrected. For VFD driven motors, in my opinion, NDE bearing needs to be insulated. Also. A grounding brush shall be provided to drain the stray current in non-hazadous area. In hazadous area, what would you recommend to do?
 

RE: Motor Questions

IEEE 841 was not specifically written for motors fed from VFDs - it is more general.  So any motor requirements specific to VFD applications would have to be added to your specification.  

 

David Castor
www.cvoes.com

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