# A quick question on three phase ac

1. Jan 3, 2012

### StephenD420

Hello everyone

I am trying to make a small three phase ac stator so a rotating magnetic field will be produced. I can use a ring with an outer diameter of 3 inches and an inner diameter of 1.5 inches with each of the six poles being 1 inch with about 100 turns of 24 magnet wire or a ring with an outer diameter of 8 inches and an inner diameter of 6 inches with each of the six poles being 2 inches with about 200 turns of 24 magnet wire. Since I live in the US we only have single phase ac, not three phase. I bought a variable frequency drive that produces three phase ac from single phase ac but it is only 4 amps and since I would like to make my magnetic field about .5 to 1 Tesla I do not know if that will be enough? Is it enough? Will this be enough turns to get the .5 to 1 Tesla?

The most important question I have regarding the three phase power is that I know you can use 3 individual single phase ac lines and use a capacitor to make two of the three legs 90 degrees apart. Is there a way to use capacitors to make the second leg 120 degrees out of phase from the first leg and the third leg 240 degrees out of phase from the first leg?

Thank you so much for your help.
Stephen

Last edited: Jan 3, 2012
2. Jan 3, 2012

### StephenD420

oh the small ring is about 1/8 inch in depth with 1/8 inch depth coil forms(iron or steel) and the larger ring is about 1/8 inch in depth with 1/2 inch depth coil forms(iron or steel)

Thanks
Stephen

3. Jan 3, 2012

### Bobbywhy

No, you cannot make 3 phase power using 3 individual single phase ac lines and capacitors.

4. Jan 3, 2012

### sophiecentaur

It was common to use a 'shaded pole' in order to get an induction motor to work by turning a single phase supply into two phases. All old tape recorders and record players used this cheap arrangement.

Using the right combination of R, L and C and a transformer (to get a phase reversal), you can produce any phase shift you want but it can involve dissipating a lot of power in your resistor (likewise, a shaded pole motor runs hot, although it only delivers very low mechanical power).

5. Jan 4, 2012

### StephenD420

How about just using two ac lines with one haivng a capacitor in series? Would that create a rotating magnetic field or would it be pulsing, as I want it to rotate counterclockwise in space around the inside of the stator ring?

Also, how do you layer coil turns for a coil? Do you just start at the top of the coil form and then coil over the top of the previous coil in the same direction and then just twist the two endings together for the leads at the top and bottom of the coil?

Thanks.
Stephen