DC motor risers break 2

[Skogsgurra]

Two 500 V 1500 kW DC motors for a reversing rolling mill have had catastrophic failures in that the risers have broken and (as it is assumed) caused a collector round-flash. In both cases it happened after around three months of operation and there is no sign of arcing or other electrical damage to the breaks. They look like fatigue breaks.

There are some speculations as to the reason for the breaks. I do not disclose what the thoughts are, because we would like some unbiased and fresh thoughts. What are the more common reasons for a case like this?

Gunnar Englund

http://www.gke.org

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Half full - Half empty? I don't mind. It's what in it that counts.

 

[panter]

Hello, everyone
I mentioned that we have a lot of electric motors with a similar form of risers .Yesterday we had inspection of several DC motors and I send a picture how does it look this part on them.


Good luck!

 

[waross]

Hello Gunnar;
I may be missing something that has been reported already.

Need to add that the fan is on in all the pictures in the 2 Feb 16 20:43 post.

Have you done a test without the fan running, to isolate the cause to air flow?
I am sure that you have, but it will be nice to have that information stated.
Apologies if I have missed this information in previous posts.

Bill
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"Why not the best?"
Jimmy Carter