With some trepidation, I have to say that I don't think it's "just a
rotary transformer". Energy must be stored and released somewhere to
create a third phase, because a third phase provides power when there
is none available from the mains (during zero crossings).

One way to check this (and perhaps prove me wrong) would be to make
measurements of phase currents (with no "tuning" capacitors) with
various loads with and without additional mass (flywheel) on the rotor
of the idler motor.

It would also be interesting to observe rotor speed on the idler as
load is increased on the driven motor. If it decreases, that would
suggest that some exchange between mechanical power and electric
power is taking place in the idler, with the process of generating
the third phase creating countertorque that slows the idler rotor.

Fitch is *very* busy designing his new house at the moment, but he'll
be done with that eventually and have time again for thinking about
other things.

On 30 Aug 2004 18:34:58 GMT, (Charles A.
Sherwood) wrote:

I probably first saw the number from Fitch Williams. Likewise
the old saw that the 3600 rpm motors don't make good converters.

I looked at some of Fitch's old posts. He contents that any good
motor will make a good RPC. The original theory was that a 3600
RPM motor will have more mass and hold more energy for that peak.
Fitch debunks that theory with his own theory. His theory is that
the idler motor is a rotary transformer not a flywheel. If the motor
is big enough and has enough copper and iron to make the transformation
the motor RPM doesn't matter.

I have been following this thread and experimenting a bit on my own.
I now believe that a RPC isn't doing much until the load motor has
a significant load. Both motors are pretty much running on single
phase. At some point, the load motor starts to slow down(ie slip)
and the RPC motor is still running at full speed and starts suppling
some power to the load motor on the third leg.
Maybe my theory is all wet, but I have tried connecting up three
different motors without balancing caps and I see almost no current
in the third leg when the motors are unloaded.

chuck