motor contactor failure

by Jim
(Kansas)

I have a dual stage compressor with a 15 hp 220v motor. The control contactor has failed for the third time in 2 years. The control is motor rated for 20 hp, but one of the contacts has been burned all three times. When I check line voltage it is 110 per leg.

I've asked several electricians and none have much idea.

After 1st failure I took motor to specialty motor shop and it tested fine.

2nd time I thought perhaps vibration of contactor was problem so moved control box to wall.

Third time I'm clueless. Suggestions would be greatly appreciated!

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Bill says...

Jim, your problem is way beyond my capability to diagnose on line, or even in person, for that matter.

Point chatter is a recognized cause of burnt points.

I'm throwing this open to the gallery. Anyone help Jim out, please?

Cheers,

Bill