Motor Arcing

[tw/nci]

Just came from replacing a motor for a pnuematic air compressor. This would be the 3rd motor in 2 years. The motor is a Baldor 2HP motor 115/230V it is wired for 230. RLA are under nameplate by about 2 amps. Was wondering why sometimes there would be an excessive arc in the back end of the motor coming from the centrifugal switch. The motor shop has said that the failed motors show arcing to the rear bearing causing bearing failure. I was wondering what could be causing this. Thanks for any help.

 

[Cold Fusion]

... Was wondering why sometimes there would be an excessive arc in the back end of the motor coming from the centrifugal switch. ...

Assusmption: the motor shop has checked the start/run capacitor(s).

The unloader valve isn't working. The motor is starting with the compressor loaded.

cf