Subject: Re: VAX7000 3-phase
To: Brian Hechinger , vax <>
From: Chuck Dickman <>
List: port-vax
Date: 03/04/2002 19:13:36
Brian Hechinger wrote:
> On Mon, Mar 04, 2002 at 03:06:22PM -0800, Chuck McManis wrote:
> > Of course something like a TEMCo phase converter could also be used.
> that's cool and all, but how do i convert HP to A?  i would need to be able to
> figure out how much HorsePower my VAXen have.  how does one do that?  is it
> based on size?  it takes three horses to pull my vax?  so it's a 3HP model? ;)

A 3HP motor puts out about 2.2kW. Motor efficiency means that it will
draw more
power than that. Starting current can be much higher (6x) until the
motor is
up to speed.

The thing about running on single phase is that you will derate the
supply output
to 2/3. I guess whether this will work or not depends on how close to
capacity the
supply is running at.

3phase motors will run on 2phase power, they just won't start or put out
full rated HP.
These rotary converters are just 3phase motors with some means of
getting them
spinning. Probably an extra winding or phase shifter that drops out once
rotor starts spinning.   

What are the name plate power requirements for this "big" machines? I am
what they have in the computer room, 208-3-60 probably in the US. 

> -brian