Induction motor won't start

[email protected] wrote:
> 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
>
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

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

OK Thanks a bunch.

Shailesh.

[email protected] wrote:

> 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)

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.

--
Jack Novak
Buffalo, NY - USA
[email protected]
(Remove -SPAM- to send email)

On Fri, 16 Sep 2005 20:41:28 -0400, Fred <[email protected]> wrote:

>[email protected] wrote:
>> 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
>>
>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


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.