Compressor & Voltage Questions

[Sleeper]

A while ago I got my first compressor, it is an old Kellogg American compressor that I got for $100. When I bought it, it was running and was wired for 220V power. When I got it home I rewired it for 110V according to the diagram on the control box but I can’t get it to run in my garage.

The power situation is this: I have a detached garage with NO permanent electrical power. Everything in the building is run from a 120V 20A GFI outlet, through a 100 foot long 10 Gauge 3 wire extension cord. To try to run the compressor I plugged only the compressor into the extension cord and all I get is a humming sound from the motor.

The compressor specs are: 2 stage Kellogg American with a 321TV pump,
the motor is an old GE single phase motor with the following specs;
HP 1 ½
Volts 115/230
Amp 20.8/10.4
RPM 1725

I think the motor is a capacitor start motor, but I can’t tell if I have wired it wrong or if I simply can’t pull enough amperage through the cord to run it? I know very little about electrical wiring and less about compressors so any ideas or advice would help.
Thanks

 

[D.J.]

Re: Compressor & Voltage Questions

Some of those motors had a switch on the side of the motor with a screw holding the switch in either the 115 or the 240 setting. It would be a "w" shaped device with the screw holding it in a setting inside one of the V's of the W. Man this is hard to explain with out a picture. I see what I can find later today but I don't have good luck with pictures on this site! You will need to look on ther side of the motor instead of the control box for this item!
Thanks D.J.
________
The Cigar Boss

 

[rburke65]

Does it work when you plug it in up by the house. Do you have a meter to read the voltage ai the end of the 100' cord?

 

[Cryptic1911]

not a bad idea, but i wouldn't think 100ft of 10ga would have that much voltage drop

 

[Sleeper]

Does it work when you plug it in up by the house. Do you have a meter to read the voltage ai the end of the 100' cord?

I have never had it down by the house since it has been wired for 110V. When I brought it home it was 220 then I tucked it into the back of the garage and re-wired it for 110. It's pretty big with a 60 or 80 gallon horizontal tank so moving it across the yard to the house to check isn't too tempting. I will check the line voltage with my multi-meter next time I'm there but I don't know if that will tell me what I need to know or if I need to be able to test the amperage draw under load, which I have no idea how to do?

 

[APEowner]

Even if you get that to start you shouldn't run it. You're trying to run a 20.8 amp motor off a 20 amp circuit. I suspect that you've got a voltage drop problem in both the cord and the wires run to the outlet. They're probably not 10GA and I bet if you could reach them their pretty darn hot when you try and run the compressor. In my mind the real question is why the breaker didn't kick.

 

[Torque1st]

Breakers have a time-current relationship. Nevertheless that motor is too big for that circuit.

The capacitor may also be bad.

 

[wineslob]

The cap (as said before) could be bad, or you got the motor wiring wrong. Recheck the motor leads.

 

[Sleeper]

Would the capacitor need some charge time to build up enough current to start the motor?

 

[RPH]

No, the cap is sized to give the proper phase shift to get rotation going. So long as it's the original. Caps go bad though. Does the motor make any noise or attempt to rotate? Does it sit there and kind of vibrate the shaft?

 

[911garage]

I think you should think about input voltage as you are trying to run a 1.5 hp on 120. This will greatly reduce the life of the motor not to mention the efficiency. It is my experience running the motor on 120 will not only reduce the motor life but the pressure switch as well. Even though the motor is dual voltage the compressor controls may not be heavy enough to handle the load.