Convert 4 wire electric motor to 3 wire?


Old 01-27-13, 04:22 AM
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Question Convert 4 wire electric motor to 3 wire?


I have just bought an older electric .5 HP motor. It is marked as 250v, 3.7 A, AC 1 phase.

It has four wires in the cord (the plug was missing) red, blue, green and white.

What I am wondering is, is it possible to convert this to a three pin plug, positive, negative and neutral?
I live in Australia where our standard power supply is 240 v, AC 2 phase.

If it cant be done, I will get rid of it.


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Old 01-27-13, 05:21 AM
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It is very likely that this could be done. But based on your assessment, you may be better off taking this to a motor shop for wiring. At the very least, we will need some motor nameplate/wiring diagram and your ability to do continuity checks.
Old 01-27-13, 08:30 AM
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Welcome to the forums! This is mainly a US site but I will try to help.

In the US we have two common electrical systems in use. Single phase, which is derived from a single transformer that is center taped and grounded for the neutral for 120 volt loads. This is used mostly in residential. The other is three phase, which uses three transformers tied together and either corner grounded, or one transformer is center tapped.

Do you have a single transformer serving your home?

A single phase motor should only have 3 wires to it, either hot/hot/ground, or hot/neutral/ground. Are you sure all the wires are connected to the motor? Is the a multi-speed motor?
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