On Sat, 27 Sep 2008 19:23:28 -0700 (PDT), Vernon
wrote:


To everybody who answered. Thanks! Upon reflection a rotary phase
converter will suit us to a tee. I have already started googling and
quickly found some "how to" instructions. About a year ago, when I
went to pick up an auction item I bought, the auctioneer gave me a
huge plenum box that sat atop a multi-story commercial building. It
was the cooler / blower for the entire building! It is a large, well
insulated box, containing a large blower driven by a 3 phase motor. I
don't know the horse power of the motor. But I'm guessing about 15
HP.

I also don't know the voltage. But I will find out tomorrow when we
go to our farm. For purposes of discussion and assuming that it IS a
15 HP, 240V 3 phase motor, would this be overkill as an idler motor?
I actually have a couple of other 3 phase tools I've had forever that
I haven't been able to use for the same reason. One of these is a
very large band saw!

It sounds like with a properly designed and built unit I can power all
of this stuff simultaneously. These a a 48" bandsaw, a Delta
Unisaw, and the newly acquired mill. The band saw probably has the
biggest motor. But I'm pretty sure all of these motors are smaller
than the motor in the air conditioner blower box.

Tomorrow I will get the technical specs off the motor data plate.

Depending on the building size it could be anywhere from 10HP to
50HP - and anything over 15 would most likely be 480V or 240/480V.
Unless you are talking Canada, then it could be 575V.

Be careful to provide cooling if needed - some of those motors are
rated "Air Over" on the nameplate, and have to have external forced
air cooling flow. The motor mounted inside the fan plenum would have
cooled itself, but not if you reuse it as a rotary converter - you
will need a fan.

Even if you get a small propeller style fan for a condensing unit
and put it on the output shaft - they make "Universal" blades and hubs
that mix and match, because you will have a Big Shaft and only need a
little blade.

-- Bruce --