D-shaping Of Dc Motor Commutator

[AB2005]

Dear Engineers

 

“D-Shaping of commutator” (deep lines on commutator with passage of time) is a common problem which has to be faced by people with DC motors. This problem is more critical in such region where environment is dusty like us. Although we daily clean the motor filter and replace the filter in monthly based but we could not overcome on this “Virus”. Attached is the picture of a commutator of a 49KW DC motor Leroy Somer brand which D-Shaped just after 18,000 working hours. We did a “Clean Cut” process on a lath machine and installed but if this (D-Shaping) would be continues, I think commutator would have to be ruin just after two more “Clean Cuts”.

 

Is there any idea to overcome on this problem?

D-Shaped Commutator

[Eurybates]

The reason why nobody has replied to your post is most likely because it is very hard to see details of comm wear in the photo. It simply looks like a roller coaster. I can see there are dust grooves which is good!. The question should be "why has this happened now?" Have you recently had the machine serviced? Did you replace brushes and are they the correct grade? What about brush spring tension? When it was undercut, were the comm segments bevelled? You should have a ducting result sheet for exact (or to 2 decimal places) resistances. As for foreign contaminent ..there would be lots of thin little lines around comm. I think (going by the picture) that you have premature wear, where the brushes have been running!.

 

In other words, I don't really know. You should take this machine to a motor rewinder/repairer shop or ring up a company who deals in supplying brushes to industry such as morganite carbon (thats not a plug) they are just an example I know of. They will take one look at the comm and tell you why. Sometimes it is worth spending the money now to get problems sorted before they get out of hand.

 

Apart from the above...all I can suggest, is that you upload a better photo.

[AB2005]

That motor had been serviced in last year i.e. CLEAN CUT on its commutator, changed its bearings and cleand all the motor. Up to that time, it is ok. Lets see what happen in future.