Spark problem of DC motor

[PAP]

Dear all
Anyone please help me about the problem of a lot of spraking at commutator - carbon brush of a large DC motor.
- Can I use abrasive material to resurface commutator? What material that I can use?
- I found some dull surface on commuatator occur consecutively but not all of commutators ,how about this evidence?

The spec. of motor :400hp, Arm 500V,640A / Excite 300V ,8.71A , 1750/2000 rpm . Operating current is around 440A.
Thank you in advace for your kindly reply.
Best regards
Prasit P.

 

[hacksaw]

resurfacing the commutator os common, but you need to get specific instructions form your motor supplier.

 

[gpedens]

Prasit try looking at this website.

http://www.helwigcarbon.com/index.asp?PID=12

Many things can cause brush problems. The commutator should have a film on it, but some chemicals or weather conditions can damage the film. You could have the wrong brush, the grooves between the commutator bars may be filled with carbon dust from the brush or you could have a armature winding problem. Does the film appear to be smooth or does it have light and dark lines. Is there vibration?

Thank You,Radar. Duke Power

 

[rewindr]

A few reasons for sparking include; Low spring tension, poor brush seating, wrong brush grade, too lightly or too heavily loaded, shorted interpoles, off neutral brush location, commutator condition including roundness, film, undercutting and edge condition, vibration and poor quality DC power.

Just to name a few but there are about a thousand more.

Get to a competent motor repair shop and get advice. Sparking will definitely lead to premature motor failure.

 

[prewrathrap]

" I found some dull surface on commuatator occur consecutively but not all of commutators ,how about this evidence?"

Sounds like you might have some type of misalignment between commutators and brushes such as shaft not being prefectly round bent shaft or problem with alignment of brushes. I would check these clearances with manufacturers spec.