Motor bearing temperatures

[stratford]

Hello to all. On site we have a 6.3kV motor with Drive end bearing D625-6322-C3. On this bearing we experience temperatures to 61 oC. Is this normal wroking temperature? The protection relay of the motor trips at 70 oC. I think this is a little bit more sensitve than usuall. In other applications we have motor tripping at 90-100 oC temperature of bearings. Can you help on this? Also i want to ask how can i understand the type of baring from the part number.

 

[Skogsgurra]

The 90-100 C is OK. If it is bearing temperature. Sometimes, it is difficult to measure bearing temperature directly. The temperature measured will then be lower than actual bearing temperature and the trip temperature must be set accordingly.

Translation can be done using the manufacturer's cataloge. In your case, it seems to be a DGBB (63xx and 62xx are DGBBs) with a 110 mm shaft diameter (the yy22 tells shaft diameter if you multiply with 5). Tolerance is C3, which is a normal tolerance.

The D625 is something that I cannot say off the top of my head. See manufacturer's catalog.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[electricpete]

Not to nitpick... but C3 is an internal clearance, not a tolerance. ABEC-5 is a tolerance class. The rest I agree with... don't know about D625 either.

I agree 70C sounds ridiculously low for a trip. Particularly if you're measuring the outer ring temperature, but also even if it were a housing temperature. Unless there were some very unique considerations or experience associated with this motor.





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[Skogsgurra]

My wrong. I mix these two words up quite often.

Welcome back, Pete! ;-)

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...