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I have a motor thats rated for 220V single phase. My house has 240V single phase. Im trying to run this motor but it doesn't budge and I don't even hear a hum. I know power is getting to it from checking with a multimeter. Could it possibly have burned from too high of voltage?

Secondly, if wired improperly, say, ground was accidentally switched with one of the hot wires running to the motor, could this somehow burn the motor?

Not sure whats going on with this thing, and I don't see any reset buttons either or fuses either.

Thanks.

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  • $\begingroup$ Can you rotate the shaft manually (without any electricity wired in)? $\endgroup$
    – Carl Witthoft
    Commented Apr 30, 2018 at 17:50

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for short periods, 240VAC will not burn out a 220VAC motor. furthermore, switching the polarity of the wires will not blow up the motor. here are the things to check:

to begin with, disconnect the 240 VAC power and apply an ohmmeter to the SAME motor terminals to which you had applied the 240VAC power. your ohmmeter should read almost ZERO ohms. If it reads high ohms, either the windings of the motor are burnt open (throw the motor away) OR the terminals you chose are not those used to power the motor.

How can this be? in a single-phase motor, two of the wire terminals leading to the motor go to the stator winding and the third terminal (the green ground wire) is connected to the motor housing. connecting one of the 240VAC leads to one of the stator terminals and the other to ground will not power up the motor.

furthermore, in a single-phase motor there is a switch which temporarily patches in a capacitor (the start capacitor) which furnishes a phase lag to one set of stator coils in order to get the motor to start from zero RPM and spin up to speed, after which the capacitor is patched out of the circuit. if this switch is bad, applying power to the motor terminals will not start the motor. If your motor is of the "capacitor-start" type and it won't start, you must check the proper operation of the start switch as well.

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  • $\begingroup$ Thanks Niels, I checked the resistence i got 2 ohms (whew all good). But then I looked more closely at the wiring and became more confused. I have a green, a black and a white wire from my wall. When I check the voltage between the green and white, or the green and black I get 120 V. When I check between the black and white (the hot wires), I get like 3 volts. shouldn't I be getting 240 Volts? is this the problem? $\endgroup$
    – Troy C
    Commented Apr 30, 2018 at 22:24
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    $\begingroup$ @troyc, in the USA we get 240VAC single phase with two 120VAC lines that are 180 degrees out of phase, so that when one line is climbing towards +120 volts the other is dropping to -120 volts. ordinarily this means that a connection between either hot line and green (ground) will read 120VAC, which is what you report- However this means that you better be getting 240VAC between the two hot lines which you are not. it sounds like your outlet is miswired to two 120VAC hots that are in phase, which is wrongo-bongo. can you trace the two lines back to your breaker box? $\endgroup$
    – niels nielsen
    Commented Apr 30, 2018 at 22:55
  • $\begingroup$ Very wrongo-bongo. I plugged the motor into a different 240 outlet I have and it started right up. Something is definitely wrong with the outlet but i haven't had a chance to check the wiring yet. Ill have to get on that. Well thanks for helping me work through that. I actually learned a lot about AC induction motors through you and further researching topics you mentioned. Thanks $\endgroup$
    – Troy C
    Commented May 1, 2018 at 1:02
  • $\begingroup$ right on! bear in mind that although you and I might think house wiring is a solved problem, the errors that get made by the "professionals" are stunning. Best of luck with it! -NN $\endgroup$
    – niels nielsen
    Commented May 1, 2018 at 1:34
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Which country are you in? As UK used to be 240 but dropped to 230 to match with France, France and all EU moved from 220 to 230 for same reason.

The 240 did not fry your motor, something else is wrong / broken.

The variation of +10% -6% permitted on the actual voltage received at a property covers this variation anyway.

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  • $\begingroup$ in the US. Think houses used to be 110/220 but now days they are mostly 120/240. And for some reason we still say its 220V when its really 240Vs as common nomenclature :-/ I think at least. $\endgroup$
    – Troy C
    Commented Apr 30, 2018 at 22:27
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If it an efficiently designed motor, there will be a 'magnetisation current' component to the input current, which lags almost 90 deg., and a load current component. The magnetisation current (that provides the magnetic field) will increase, but this will give it more torque for the same load current, so the load current (which is greater) will decrease. This means, on full load, the motor will probably take a bit less current.

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