Greg Dermer wrote...

I didn't see where he explicitly said he disconnected the pony motor.
*IF* it's still connected to the line, and *if* the belting arrangement
will run the pony motor faster than synchonous speed while being driven
by the idler motor, then it will act like an induction generator and be
loaded by the power line, causing heating.

In the third paragraph of the original post, I said "whenever the idler
contactor is engaged, the pony motor contactor is disengaged. I double-
checked and there is no line current into the pony motor when the idler
is running."

Wherefor the conundrum.

Jim