Napa brand 82378vat 7.5HP tripping the breaker at startup (much more info below)

by Jeff
(Maine)

We have an air compressor, Napa brand 82378vat 7.5HP that recently burnt the windings of the back of the motor after 9 years of daily use - we had it re-wrapped, new capacitors etc and we then threw the heavy SOB back into place, had it all hooked up.. it initially starts for maybe 4 seconds then blows the breaker (30 amp, we've tried 40,50 also with same effect) If you take the belts off - it starts and runs fine. We removed the feed tube from the compressor to the tank, same things happens.

It freely turns by hand (the compressor) and it drawing *crazy* amps when hooked up(I dont remember the numbers now Obviously, if it's tripping those big breakers) With the belts off it's drawing 12.5 on each lead, which is fine.

We took the end cap off the compressor to see if the weights had come apart and bound up, but they're fine other than being a little dirty.

Any ideas what could be causing this? I ordered a new compressor but i'd rather find out it was the pressure switch on the tank (from reading the posts here it seems that's a likely culprit) But I just wanted to see what you all had for ideas.

I hope the information was enough to be helpfull - thanks in advance.

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Bill says....

I don't think it's the pressure switch, Jeff. If the switch was shorting on startup, it wouldn't take 4 seconds to blow the breakers.

Very difficult to assess, but I'm wondering about the capacitors?

Anyone else?

Bill