Induction motor won't start

[potnis2000]

Hi fellow woodworkers:

I have a shop compressor with a 220V induction motor that would not start. It does not hum or create any noise whatsoever when I flip the switch. I browsed through groups and through Google but came with cases when the motors at lease hummed to indicate that they were getting a juice.

Here are a few diagnostics I ran:

Tested voltage at the switch terminals of the motor. The voltage across two out of phase leads is 240 volts when the switch is in off position. The voltage is almost zero when the switch is flicked on.

Power switch works fine and correctly makes and breaks the contacts.

What other tests I need to run before opening the motor housing.

Thanks

Shailesh

[Fred]

These motors have few parts to fail. The start capacitor and the start (centrofugal) switch are the most likely. Pretty much, the only other problem you would see is a loose or broken wire. Fred

[Frank Boettcher]

Could be but the centrifugal switch in most cases is closed at start and opens to take the start circuit out of the picture when the motor gets up to speed. then it is spring loaded to close when the motor comes down. Usually fails by getting dust between the contacts or a broken spring. But when it fails you still should get a hum with the motor trying to start without the start capacitor in the circuit and having a hard time doing it..

Are you sure there isn't a fault in the pressure switch circuit that is keeping the motor from starting. I'm not sure how that works but you might check all that wiring.

[potnis2000]

I do not think that the pressure switch is malfunctioning. This is because I see that it cprrectly opens and closes the circuits between the line and load terminals of both of the 110 out of the phase lines.

Any idea (This is for everybody in this group) whare I can buy the capacitor (do I have to go to the manufacturer? and get the part)

Thanks

Shailesh

[no(SPAM)vasys]

Do a search for "electric motor repair" in your area. The capacitor are pretty much standard and should run about $10.00. Take the old one with you. They can use it to match it up and they may test the old one before selling you a new one.

[potnis2000]

OK Thanks a bunch.

Shailesh.