On Fri, 17 Dec 2004 15:25:00 GMT, "Al MacDonald"
wrote:

I latched onto an older horizontal mill that runs on 3hp 440V 3ph power. My
plan is to hook up a 220V rotary phase converter to a 3KVa 3ph transformer
220/440 and then to the mill. Does anyone see anything obviously wrong with
my plan? I suppose I could try and find a 220/440 single phase transformer
and then a 440V single to 3ph rotary converter but I think this way might be
much more expensive. Thanks, al.

Check the motor nameplate in the mill, see if it's straight 480V or
240V/480V dual voltage (which is more common) and also check if it is
"inverter duty" rated.

Stepping voltage up for big tools is a problem, as you may not have
enough power feed at your house to drive it after you figure in
transformer losses and start surges - especially if your house only
has a 100A 120/240V 1PH panel. "Watts is watts", and you double the
current going in to double the voltage going out.

Instead of a phase converter, you may be better off with an inverter
drive that will run the 3PH motor off 1PH power, and can 'soft start'
the motor to reduce the start current surge to something your power
service can handle.

-- Bruce --

--
Bruce L. Bergman, Woodland Hills (Los Angeles) CA - Desktop
Electrician for Westend Electric - CA726700
5737 Kanan Rd. #359, Agoura CA 91301 (818) 889-9545
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