Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!nwnexus!apex!chuckh
From: chuckh@apex.com (Chuck Huffington)
Newsgroups: sci.electronics
Subject: Re: 1 phase to 3 phase conversion
Keywords: phase conversion
Message-ID: <1991Apr9.004732.8605@apex.com>
Date: 9 Apr 91 00:47:32 GMT
References: <1991Mar28.191005.1653@rodan.acs.syr.edu> <3613@polari.UUCP> <4725@osc.COM>
Reply-To: chuckh@apex.UUCP (Chuck Huffington)
Distribution: na
Organization: Apex Computer Co., Redmond  WA
Lines: 24

In article <4725@osc.COM> jgk@osc.COM (Joe Keane) writes:
|Why would you want to do such a thing?  One example is electric trains.
|Clearly you can only get a single phase from a catenary or power rail.  But
|you may still want to use three-phase motors, just because they're so nice.
|So this is a good application for phase conversion.
|Joe Keane, not a real EE
|jgk@osc.com (...!uunet!stratus!osc!jgk)

Another really good reason is that you can't always get 3 phase power
when you need it.  A lot of machine tools have 3 phase motors.
People who have home machine shops often find it nearly impossible to
get three phase power.  If the area you live in was not wired 3 phase
it will cost a fortune to get it.  A lot of residential areas are NOT
supplied with three phase and you will pay by the foot to the nearest
three phase power.  I've seen it to be miles away.

Rotary converters are not that hard to get.  They aren't free but they
aren't that expensive either.  I've seen some pretty cheap solid state
stuff, but have never tried one.  I have third hand reports that they
are not very reliable.  The rotary ones are.  The cheap solid state ones
also only work on lightly loaded motors (<75% load).

As I recall a rotary unit to run a 7hp motor will weigh about 100 lbs and
cost under $1000.