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Commutator Arcing!!

Posted By: williams

Commutator Arcing!! - 02/08/11 12:48 AM

What I have is an old Rigid Pipe Threader unit 535 series. My original problem with this was that it was tripping the breaker. After doing a few quick checks and found nothing really wrong I took the motor out to find the Stator windings had arced and had a short. Thinking this was the problem I ordered a new field, bearings, brushes and brush wires would solve this issue. After reinstalling the motor to give her a try there was some sparking going on the commutator between the brushes and then 10 seconds later a tripped breaker. Now this obviously is now pointing to the armature and com but is there any thing I can do for testing before I order a new one or at least learn something for the next time.
Thanks
Posted By: williams

Re: Commutator Arcing!! - 02/09/11 11:26 PM

Ok here is what I have found. This motor is universal AC or DC and I am using 120 V AC. The first test I did was use a Ohm Meter to see if there was any continuity between the commutator and the shaft and was in fact open. Then I use a test lamp and applied 120v to the shaft and tested to each commutator bar to see if I would get a light and I did which means the insulation was broken down. The reason why the ohm test never worked was because it only applies 10VDC were the test light is 120VAC. I never used this test light before and it worked well.
Posted By: Tesla

Re: Commutator Arcing!! - 02/10/11 01:56 AM

Over time the two components that wear are the brushes -- which are cheap and easy to swap -- and the commutator.

Without the trick equipment most commutators can't be 'tuned up.'

A worn commutator will just ruin new brushes in short order.
Posted By: twh

Re: Commutator Arcing!! - 02/10/11 04:40 AM

For next time, a megger is a better tool for testing a motor.
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