Re: Egg of Columbus

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Ed Phillips <evp@xxxxxxxxxxx>


> Original poster: Daniel Kline <daniel_kline@xxxxxxxxxxx>
>
> It's not a toroidal winding. It's four separate polyphase windings.


...on a toroidal form.
Right?
I knew it was multiphase, didn't realize it used four phases though!
I assume it's possible to build one which uses only three.  I'd love
to build one, but I'd have to synthesize the multiphase power.  If it
can be done with only two phases and windings, it gets lots easier-
just add a capacitor, like a squirrel cage motor!

- G.

......................................
Is it weird in here, or is it just me?"

   Not weird at all.  Consider this:  Take a 
ring of magnetic material and wind one coil on 
the left side, with wire going clockwise around 
it.  Wind a second one on the other side with 
wire going CCW.  Hook the wires coming from the 
top of the coils together and hook the wires 
coming from the bottom together and feed current 
into the parallel combination.  No net flux "runs 
around " the core but there will be a net 
magnetic field from top to botton.  Wind another 
set of two turns on top and bottom and connect 
together; they will form a magnetic field which 
is oriented horizontally across the core.  Draw a 
picture and you'll see what I mean.  Now excite 
the two pairs of windings with voltages 90° out 
of phase (in other words, a two-phase system) and 
you'll have a rotating field as viewed from the 
axis of the core.  Put a conducting object at the 
center and eddy currents will be induced which 
can cause it to rotate.  I'm pretty sure this is what Tesla described.
It's also possible to use three windings and three-phase excitation.
   Obviously you can wind all coils in the same 
direction and reverse connections to the leads 
but I think the description above is simpler.

Ed