Saylor Beall air compressor trips circuit breaker immediately after starting
Saylor Beall air compressor
I have a really perplexing problem with an older air compressor. The compressor is an old 2-stage Saylor Beall 80 gallon with a 240v 5HP Dayton electric motor.
When the compressor is plugged in, the motor starts and begins to turn the compressor pump, but then trips the circuit breaker right away. I have checked the current with an AC clamp meter, and the motor is drawing a peak of 213 amps on startup with the belts hooked up to the compressor.
I have tried unhooking the compressor from the tank so that the compressor head cannot build up pressure. This did not change my results. I still tripped the breaker with the tank unhooked.
If I remove the belts so that the motor is not coupled to the compressor head, the motor will start and run fine, but does make a lot of noise like the bearings may not be in the best shape. When I remove power to the motor, the motor keeps spinning for a LONG time. As the motor spins down, there is a point at which I hear a click and the speed decreases quite suddenly. It's almost as if there is a brake inside the motor that kicks in at this point.
When I hook the belts back up after running the motor by itself as described above, I can start and run the compressor successfully one time. The compressor will run until it reaches the cutout pressure and then shut down. After this one successful run, I cannot start the compressor again without tripping the breaker.
There are three capacitors on top of the electric motor. One is a 25MFD oval cap, and the other two are round 1070MFD. I have tested these with the capacitance function on my AC clamp meter, and they all test OK.
I would greatly appreciate any help, as I am really stumped with this.