Creating a 3-phase circuit

I've never messed with 3 phase , but I'd have though you would need 3 separate cores.
I don't think the separate phases will stay separate once they are magnetising a common core.
EG. 3 separate phases in.... 3 virtually identical jumbled waveforms (all in phase with eachother) out?

I'm quite happy to be enlightened if I'm under some missaprehension about this.
Del

I will keep this short (in part because I am simultaneously watching a movie), to create this demonstration rig you need a three-phase supply.

I am going to stop there as working with three-phase 220V is extremely dangerous and I seriously advise against trying to replicate this rig unless you know what you are doing (have electrical training), have the proper safety equipment and circuit protection and work in a controlled and monitored environment with a handy fire extinguisher.

Just enjoy the You-Tube videos and don't believe everything you see on the internet.

Good point!

If you really want to experiment with phasing, do it at low powers from a signal generator or with pulses or higher frequencies using ferrite torroids.... much safer/cheaper.
I wouldn't bother unless you have a decent oscilloscope and know how to use it.

Del

You could have three separate windings on the one toroid. What you will have is (assuming you are using household power socket of 110 or 240 volts, single phase coming in and single phase coming out.

I believe you want to imitate a rotating magnetic field. Attaching a three phase switch to your idea will not generate three phase power or even a rotating magnetic field if you attach your power source to household electricity.

To get a three phase supply out of a single, you would need some type of switching to control phase angle.

I recommend that you avoid such dangerous voltages and instead make your own DC MCU (Motor Control Unit).

There are heaps of IC's available that require minimal extra components to get a three phase DC switching motor controller. All you have to do is wind your toroid accordingly. Again heaps of info on the web regarding this.

Play it safe with low amperage DC and you can start spinning...

Why?

I was planning to use 110v starting out. I have tried this with Dc but the field doesn't rotate like AC would because of its sin wave output and DC wouldn't create the kind of field I want, which is the field that is demonstrated in the youtube video, as I have tried doing this experiment with DC current. It did not work very well at all. And I have used AC and DC currents for years. Many members of my family are engineers. So I know how to use equipment safely.

So how would I connect each separate coil to one another and to the 3-way switch to create the effect that is modeled on the youtube video?

Thanks for all of the help.
Stephen

I am trying to make a stator ring like the ones described in:
http://www.tpub.com/neets/book5/18a.htm
http://www.geocities.com/vijayakumar777/inductionmotor/inductionmotor.html
http://www.mpoweruk.com/motorsac.htm

How many windings per inward notch do I need to wind with the wire to make a strong field using AC? Thanks.
Stephen

Dude, looks to me like you are trying to replicate a rotating magnetic field similar to the field in a common induction motor. You are going about all wrong. The MMF (magneto motive force) produced by your coil as drawn will be confined to your toroid core. The MMF produced by three phase AC when confined to a single toroid, since they are all confined to the toroid will all add to a whopping zero! You need to orient your magnetic axes at 120 degrees to each other to get the cool rotating field. Buy a book or google some entry level text on electric circuits and magnetic circuits instead of risking a mondo fire and personal injury. There is no shame in reading and doing your research before you hurt yourself or someone else. By the way all this electrical and magnetic stuff makes sense after a while and if you go to a good school will even make you a good living.

Ok, first I'll state what should be obvious just to get this out of the way.

Three phase power is three electric power sources with identical oscillation frequency and amplitude but different phase relationships. Choosing one power phase as the zero, or reference phase; one the other two phases leads the reference by 2*π/3 radians and the other phase lags behind the reference by 2*π/3 radians (font makes an odd looking pi). This is also known as ±120°.

Winding multiple exciter coils on a single core toroidal transformer will produce one and only one magnetic flux current loop. So one and only one secondary output voltage can be generated from this. (Often this approach is done to compare current balance of the three phases, but not the point I think you are reaching for.) Three phase transformers have three magnetic field loops. The primary and secondary windings exist on the same loop of magnetic material.

To produce three voltage phases from one voltage phase something must delay the current flow. To create the rotating magnetic field you wish to create, two capacitors are used to delay the current running through the stator windings. Remember, the magnetic field is proportional to the current through a coil and not the voltage across the coil.

The three phase system is interesting and not so complicated, as many would think. I know three ways of connecting windings in this system: Y, delta and Z connection. The most common are delta(D) and Y connections. Using these connections, your transformer could have its primary and secondary coils connected as follows:Dd; Dy;Yd;Yy;(Capital letter represents the primary connection) the neutral for the y connection may or may be not accessible, depending on the load mostly.

The image shows a Dy connection. For delta connection just connect the end of one winding with the beginning of the next winding; for Y connection you just connect the ends together(or the beginnings); and you can switch between these types of connections.

A three phase transformer provides 3phase voltage and current only if you feed it in a 3 phase.

Another aspect to consider is the magnetising current or the idling current. This translates in the quality of the core and in the number of turns for the primary winding. If the core is ferrite is ok; Next consider the number of primary turns which for this voltage level is important (maybe over 100 or 200 turns for each phase).

Eventually, as the other guys said, electrosecurity is important so use fuses, circuit breakers, earthing for the core of the transformer and proper insulation.