Bad mag starter on 5hp 2electric air compressor motor?

by John

Bend pack 80 gal upright air air compressor model LS508V-501

Serial # 500000570b-005

It has a Baldor Industrial 5hp electric motor

Approx 1 month ago the compressor popped the 30 amp breaker but did not trip the magnetic stater reset.

So when main breaker was reset the breaker automatically popped again.

So upon typical visual and proper voltage tests to motor all was at 240v.

I removed capacitor cover and found 5 capacitors. 3 start capacitors and 2 run capacitors. All 3 start capacitors had blown and oil was leaking from them.

The 2 run capacitors tested ok with my Micro fared meter and showed no signs of leakage.

Replaced all 3 start capacitors and bingo all was good with zero issues for about 45 days +/-.

Now same problem again other than 2 of the 3 start capacitors went bad and one was still in spec with the run capacitors still ok.

So I purchased another brand of 3 new start capacitors from packard electric and hooked it all back up and now compressor labors to turn with zero air in tank and pops main breaker within a couple seconds.

I can run the electric motor which i removed from compressor and put on my bench and hard wired it with no mag stater and obviously no load on it and starts up and runs and runs with no issue.

Can I have a faulty mag starter causing motor not to start properly?

When compressor switch is turned on you and hear the mag clunk and then it does supply the 240v to motor.

My next test was going to temporally eliminate the mag starter and see if motor will turn compressor pump with the mag eliminated. If it does work I would assume I have a bad mag starter but this is where I'm looking for advice. Thanks for any help in advance.

Comments for Bad mag starter on 5hp 2electric air compressor motor?

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Sep 22, 2018
Mag starter ?
by: Doug in

Maybe. Are the contacts burned?

Question - are those start caps wired series or parallel?
What rating?

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