Since the running idler and load motors are directly connected in parallel,
wouldn't plug reversing with identical motors and no mechanical load have an
equal chance of reversing either motor? When running free, it seems to me
that either motor could be considered to be the source or load for the third
phase leg. I tend to believe that the idler requires more mechanical inertia
than the load to maintain the best functioning.

If an induction motor does not "generate", is induced counter EMF imaginary
and the use of common induction motors as generators impossible? There are
many ways to understand and describe how things work and I like to think of
the RPC as simply a running induction motor with the magnetized rotor
inducing EMF not only into the line energized windings (counter EMF) but
also into the unenergized and phase displaced windings. Note that, when
disconnected and still turning, an induction motor still has voltage across
its windings and loading this voltage with "braking" resistors will
mechanically load the rotor. I do not claim that this is the only way to
describe it or that any description can change the operating principles
involved.

Don Young
"Christopher Tidy" wrote in message
...
Hi all,

I'm trying to figure out if there is any benefit in adding a flywheel to a
rotary phase convertor. I've heard varying opinions on the subject. Having
thought about it myself, I've reached the following conclusions:

(i) The sag in voltage on the third line is caused by the fact that it is
not connected directly to the supply. The flywheel doesn't change this.
Nor will it change the steady speed at which the rotor turns, so unless it
has some averaging effect on a cycle-by-cycle basis which I haven't
considered, it won't affect the quality of the three phase output when the
convertor is running in a steady state.

(ii) It might be an advantage when trying to plug reverse the load motor.
As far as I can see (on the most simplistic level), the motor with the
most kinetic energy will win.

I can't seem to find any used flywheels to fit my motor, but I can get a
brand new flywheel for £40. I'm not sure if it is worth it in order to
satisfy my scientific curiousity. If I get a different motor, I can get a
flywheel for next to nothing, but that will involve lots of effort,
bartering and deals in order to get a motor which isn't quite so cool.

Any opinions and arguments? Thoughts would be appreciated...

Best wishes,

Chris