Maybe my imagination but motors running under load on a static converter
seem to vibrate. My imagination? Anybody else?

bob g.

Charles A. Sherwood wrote:

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.



I assume you are refering to me because I proposed the motor
driving alternator design a while back. (but you quoted someone else)

I have looked for surplus motors to build a phase converter but
frankly I have not found the oasis where they are available for cheap.
The shipping costs are usually the killer.

One of the reasons I proposed building a motor alternator setup
is exactly what you quote above. I already have the alternator
and a 5HP motor to drive it. So to me it is cheap.

I started experimenting with a static phase converter because I
found a used one and a couple people here stated it would
be adequate for my needs. So far it seems to be working; but
running a 3ph motor on 2 windings rubs me the wrong way; Especially
when the run current in those two windings is higher than the
full load current spec of the motor.

Someday I will build that motor alternater setup and experiment
with it too. But for now, I got lots of projects ..

chuck