Converting 3 phase power into single phase, possible?

Question

Hello, I have a problem in which I need to provide a 220V single phase from a 220V 3 phase supply. Is this type of conversion possible using a transformer?

Specifically, I have a single phase motor that draws lots of current. If I just connect it to one of the phases from the utility, I'd create too much of an imbalance, and most likely one of the breakers will interrupt. If I can somehow draw an equal amount of current on the 3 phases, then I am probably within the "circuit breaker" budget.

Thanks for any comments/answers.

Answer 1

Yes, it is possible, but not with a transformer, I'm afraid. Transformer is for stepping of voltage to a higher or lower magnitude, it's not for reducing the phase.

Now here is what we've got. You said you have a single phase motor. I'll consider it to be an induction motor as it is drawing a lot of current from the 3phase supply. It's very obvious because that's how they actually behave. To start a single phase induction motor, you'll need a starter. Most widely used starter is the capacitor starter. It's a capacitor box which will actually store the additional electrical charge drawn by the motor and then it will let the motor run at its own speed. Note that you'll need the starter only to get the motor started. Right after the motor has obtained a constant speed, you'll have to disconnect the starter from the circuit. I believe the company from which you'll but a starter will show you the connections (if you want to know that) and also when and how to disconnect. All the best.

Answer 2

I think what your looking for is a Scott-T transformer.

It is used to derive 2 phase current from 3 phase without imbalance.

220V circuits, at least in the US are actually 110V 2 phase.

So a Scott-T designed to convert 220V 3 phase to 110V 2 phase should theoretically work.  But it maybe an expensive solution.

I hope this gives you a start in the right direction.

Good Luck.

Answer 3

I assume you have a reason not the use the obvious option of replacing the motor with a three phase one, but I suggest you give it serious thought, if there is any way you can do it, it will be by far the better solution. Otherwise you might look into a soft start device for the motor which can help with the starting current, but it won't change the full load current.

The "Scott-T Transformer" is probably not a solution, it gives 2 phase output, which is different from 2 pole single phase, in 2 phase the phases are 90° apart (and 4 wires are used) , in the 2 pole single phase the two lines are 180° apart.