# Quickie Commutator Cleaning Solution



## DLG (Dec 3, 2010)

125hp 500v DC Motor: I was called to check out a motor failure. Brushes were worn down to nothing, arcing around the brush holders, commutator splattered with molten brass beads and pitted. Trying to make a temp fix until timing is better. Vacuumed, cleaned, and raked the grooves clean. Used contact polishing stick to brighten the commutator. Afterward, used contact cleaner to attempt a more thorough cleaning. Afterward, brush holders and hardware all meggered good except the commutator. It actually decreased in value to less than 1 meg(+/- .6 meg). 

I assume the contact cleaner may have contaminated the commutator by flowing carbon dust into/around it. Was unable to place portable heater on it in attempt to dry out if needed but was only able to muster up a fan.

Will return in the am to re-megger the com in hopes its resistance value has increased. If not, I am considering to flush it with alcohol in hopes of washing out carbon dust. Re-dry and pray. This has worked before for emergency repair of water immersed motors to dry out and return to service due to critcal situation.

This is a press motor for a newspaper. They don't have a spare and little maintainence budget. Trying to buy time until a trip to a motor shop is better for their production.

Have any of you tried to flush the com for a quick fix of insulation value and if so, what did you use? Any other successful approach would be greatly appreciated.

Respectfully,
Under the gun.........


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## nitro71 (Sep 17, 2009)

If you're going to flush parts you need a electrical solvent designed for electrical parts. Could try distilled water I suppose..


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## DLG (Dec 3, 2010)

First, this media is new to me. Having trouble navigating this thing. I do appreciate being able to share thoughts and experience with like people.

Understand, not sure what might wash it out if the carbon has contaminated the commutator. That is why I used the contact cleaner. But I am beginning to question my logic. I hope the ohms have increased in the am to where I don't have to try option B.

Thanks,
DLG


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## John Valdes (May 17, 2007)

I do not recommend you use any solvents on this commutator. Your description of what happened should have prompted you to start disconnecting the motor and getting your motor shop in route. If all it was was brushes worn down to the comm and it was not to bad you could have had the motor back by now. Or at least by this afternoon. You wasted all night. If your motor shop does not provide emergency 24/7 service, find another shop that does.

125 Hp is not that big. Expensive? Yes. Why no spare? It cannot be that important if they did not have enough foresight to have something to fall back on. A spare 125 Hp is not that big a deal. I bet they have more than one running just like it? Talk to them about a spare. I used to leave my DC spares at the motor shop. That way if they sat on my shelf for several years I had no warranty issues with them. I was good tool for them and a ready motor was just a phone call away.

The motor shop would have disassembled it and pressure washed it with a solvent soap, rinsed and put in the bake out oven set at 350 for around 4 -8 hours. If it megged clear, they would have resurfaced the comm and under cut it. Machine work check*, new bearings, balance and back to you today if all went well. 

* Could cause severe delay.


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## DLG (Dec 3, 2010)

Thanks for taking time to respond to my situation. I had the same response when I first cracked open the motor. I agree, the motor shop fix is the best way to go for a reliable outcome and I respect their service.

Maybe it was the moon or a senior moment, but for various reasons I decided to attempt field repair hoping to put it back into service. Following the initial readings after cleaning, I also was beginning question my decision.

This morning the readings were not what I hoped for and flushing made little improvement. But after redrying and cursory tests, voltage was reapplied to the motor. Runs good and is stable......what a relief. 

Now they can plan to send the motor to the pros at the motor shop when their schedule allows. Your points about the spares and their storage is well taken. Thanks. I hope the young manager sees the value, especially now.

This grey hair is going to exhale and celebrate with Mother tonight. Maybe I'll take her out tonight for pizza and hope it doesn't interfer with a good nights sleep.

This is my first stab at this vehicle to reach other like-minded people to discuss matters. I appreciate this service and intend to visit more often.

Thanks to all for your assistance and willingness to help.

Respectfully,
DLG


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