1Ph or 3 Ph electric motor - How do I tell which ?

I am trying to use an electric motor for a band saw but am not sure if it is 1Ph or 3Ph or both! The plate gives information for both

220-240volts and 380-420 volts.

There six wires coming out of the motor connected to a block. On one side of the block there are Blue, Grey and Red wires. On the otherside there are White, Black and Brown these three are wired together. By connecting across the Blue,Grey and Red with 240v the motor runs.

Question? If I have got the motor to run does that mean it is 1Ph or is it just running on much reduced power ?

Will the motor run happily on either 1Ph or 3Ph (with a reduced power output)

Reply to
Poor fruit cake
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Is there a capacitor on it? Can you post a picture?

You mean you connect three terminals with three phases, or what?

When it runs, do you hear any unusual sounds from it (kind of hard due to the noise of the saw, but maybe you can remove the belt or some such)?

Reply to

Check the amps to see if its pulling what the plate says...

Reply to

Hi to answer your questions.....

I just connected to the domestic 240 volts. I assumed Red was +'ve and Blue -'ve that left grey which I connected to earth. No capacitor.

It ran OK no noises, I just don't know if this is at full power or full speed. I havn't connected to the band saw yet, it is just sat on the kitchen table I have a very understanding wife, so far .

Re add a picture,,,,,, don't know how to do that. I will ask my son.


Reply to
Poor fruit cake

I will try tomorrow and let you know.

Thanks, Regards,

Reply to
Poor fruit cake

If it has a centrifugal starting switch then it is a 1-phase motor. If it has no centrifugal switch, then there are several possibilities. But, the big one is the motor RUNS on single phase (I assume that is what you are saying above). If it starts briskly in the same direction every time on single phase power, that pretty much guarantees it is truly a single-phase motor. I'm wondering if it is a multi-speed motor.


Reply to
Jon Elson

If it starts under load on single phase, it is NOT a 3 phase motor.

Reply to
clare at snyder.on.ca

Since the voltage range is related by sq.root of 3 (220 x 1.7320 = 381) it appears to be a 3-phase motor connected in delta for the low voltage and connected in star for the high voltage input. It appears that both ends the 3 windings are brought out so that either connection can be easily made. An ohmmeter check will verify my supposition quickly. In the UK, is residential supply 3-phase 220V, with one leg grounded? If so that should explain why you are able to get it to run.


Reply to
Randal O'Brian

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