Here's the situation. I have a lathe which currently
uses a single phase motor with a 145T frame. I want
to replace it with a 3 phase unit with the same frame
type, but the only motors I can find with that frame
and in the less-than-2-horse-power range run at
1140 RPM. I have a (1725 RPM) rotary phase converter
which powers another 3 phase motor in my miller. The
miller's motor is a dual speed motor (I don't know
the RPM of the two speeds, but "fast" is double the
speed of "slow". This is the stock motor in a Hardinge
TM/UM miller).

I know that adding idling motors into the circuit of a
rotary phase converter will effectively increase the
capacity of the converter, so the various motors do have
an effect on the 3 phase generation system. My question is,
will all of these different RPM motors adversely effect the
operation of the rotary converter or the quality of the
3 phase power it generates? I doubt I'll ever have both
machines running at the same time, but who knows.