Electric Motors/Compressor motor
I have an old sears air compressor with a 1hp GE motor & 12g tank. Always worked fine, I have it plugged in on its own 20amp circuit breaker alone, direct with no extension cord, one day i went to turn it on and it just made a clicking noise, so i left it for a while then tried it again now it runs for about 20 seconds then it shuts off because it trips the breaker. does this sound like one of the capacitors is bad (it has 2)? If so witch one? Or does the whole motor need to be rebuilt?
About the largest motor that will start on a 15 amp 120 residential system is 1/2 HP
NEMA rates a 1HP 115/120 volt at 16 amps it might be the motor is too much for the circuit
Not sure about the clicking noise, is it still there ?
20 seconds should get it out of locked rotor which can pull from 4 to 10 times full load, so it could be creating a voltage drop, and the breaker is just not taking the load from start,
I would have it tested on a larger system say a 50 amp system where they can get the running current no load, right there should tell if you the 20 amp breaker is going to hold it,
16 amps NEMA is average so this one might pull 20 amps depending on the ACTUAL VOLTAGE at the motor,
The clicking sound sounds like it was trying to trip the centrifugal switch and then falling below before it dropped the start circuit, so you have multiple caps are both metal cans or one plastic and one metal ? Or two plastic?
One of each is a cap start cap run, two plastic is probably a cap start with two caps wired in parallel. and if any of them on the top has a round hole and that round area is pushed out of puffed up the cap is bad, if one is bad replace all
No load or belts on the motor right?
Make sure you get it running with nothing on it first 1HP is tough in a residential circuit,
If it is dual voltage and it can be ran on 220 that might help with the wire size for a new circuit
But I would get it tested on a test circuit so you know what the running current is and then measure the voltage at the outlet and make sure if you have 114 or 121 volts utilties are not consistent even though they swear they never made a bad volt ever mine runs from 116 to 119 and even lower depending on day time of year time of day so on,
a few volts can bring the motor over the knee of the curve and that is that
There is not a good way to soft start a single phase cap motor, the low voltage is not a help
Now if it is on the compressor with a belt it could be the load of compressed air is too much to overcome PAST the start current then you would need some kind of unloader on the compressor to cure that
Find out what the exact voltage is at the outlet then find out what the running current is no load from there we can figure out what way to attack this problem