Don sez:

Not quite. The balance is a function of the load. Tune it
for proper balance with one machine (load) and if you turn on a
different one with a different horsepower, the balance will be off a
bit, as will it be when you turn on a second machine while the first is
running. (Each extra machine adds to the rotary transformer capability,
but does not add to the tuning capacitance.)

Well, it depends on how sensitive to additional "load" your RPC is. Tuning, (actually power factor
correction) in a well designed RPC is quite broad and is proportional to the ratio of load to idler
motor HP. In a good RPC voltage regulation over minor load variations is no problem. Don's
implication is correct; balance is a function of load. Good RPCs are designed to operate with a
fairly constant load to idler ratio. That is reason is it good practice to have a 1.5 to 2, or
greater, ratio.

A RPC is a strange animal, indeed. Think about it. The load(s) and idler are connected in parallel
but in order to feed a 3-phase load from a single-phase source the currents do not flow in parallel
! Balancing caps provide series resonant tuning from each side of the single-phase line to the
manufactured phase. Current flow is quite complex and defies simple math reasoning. It can be
shown that currents try to flow in opposite directions at the same time. The math system of
"symmetrical compoinents" is required to sort it all out.

Bob Swinney