In article , Old Nick says...

RPCs seem complex and prone to all sorts of vagaries

You have to understand that most of the designs you
see are highly optimized. Using an oversized idler
motor that is started with a pony motor means you
don't need any power factor correction, no balancing,
and no starting circuitry.

It gets built for free, runs forever, and never
has to be thought about. Example is the patented
"jim's stone age converter" seen he

http://www.metalworking.com/DropBox/_2000_retired_files/Conv.jpg

Your idea of using a large single phase motor to power an
excited field 3~ alternator is in principle the best way
to do this.

However because hardly anyone ever actually purchases a 3~ alternator
in the 5 hp range, and likewise 5 hp single phase motors, the
trouble is that those two things are incredibly expensive and never
available on the surplus market.

5 to 10 hp three phase motors on the other hand are literally
given away for scrap value on a regular basis. Likewise the small
1/4 hp pony motors to start the thing.

Folks build what they can afford, and what works. If you advocate
the more correct design, be prepared to put your wallet into the
breech to implement it. At the end of the day, nobody will be
able to tell the difference between the power on your wires, and
the power on my wires.

Your wires will wind up costing well over $1K. Mine are under
ten bucks.

Jim


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