shorted motor windings 1HP motor

[sdowney717]

motor has a red button breaker on top.
Motor can be wired 120 or 240 volt
motor plate says 12 amps for 120 volts.
motor pops gfci breaker instantly when plugging into a gfci circuit without the on switch turned on.
motor runs for about 20 seconds before blowing 20 amp normal breaker
motor runs about 10 seconds before blowing 15 amp breaker.
motor never blows its own red button breaker.
motor gets quite hot, especially noticed the capacitor on the side, the metal shell feeling very hot.
motor spins freely, no problem with bearings.
motor sat outside for a few years when it rained it got wet.
So what is the most likely thing wrong?
When it starts up it seems a little sluggish ( does not spin up real fast), runs at normal RPM, and you can hear the centrifugal speed switch clicking in the motor when it shuts off.
motor was only used one time then not used for about 10 years.

 

[phbsales]

Is the motor rotation correct?

Is it wired for 240 (and you're feeding it 120)?

Have you ohmed out each winding, and have you checked for continuity to ground?

 

[fefarms]

If the GFCI pops "instantly" it is very likely that there is a low resistance path from Hot or Neutral to the metal case of the motor. Confirm this with an ohmeter. Track it down and fix it, resistance from either lead to the case should be several 1000 ohms at least. There may be other problems with the motor, but they are moot until this issue is fixed.
I'd consider removing the start and run capacitors as a first step in trying to find the low resistance path.

 

[fefarms]

The red button on the motor is a thermal trip; it is not a circuit breaker and not meant to detect short circuits.

 

[rkevins]

I would take the motor apart if posible and clean (if you have not done so) you may have rust build up somewhere shorting to the case. also clean the contacts on the cint. switch.

 

[G_P]

Sounds to me that either you are running a 240v motor on 120v. Not good.

Or you are running your motor on the correct voltage with a failed start/run capacitor. Very Bad.

If it's not one of these then start checking your windings for shorts to ground.

AC motors are pretty simple devices. You should be able to find the problem with a cheap DMM with our help.

BTW... did you check for dry bearings? Physical drag could be causing the motor to pull high amps and trip the breaker.