Re: 3-phase current - you don't need caps or ider motors!
Date forwarded: Thu, 10 Dec 1998 14:00:19 -0700
Date sent: Thu, 10 Dec 1998 11:33:48 -0700
Subject: Re: 3-phase current - you don't need caps or ider motors!
Forwarded by: tesla-at-pupman-dot-com
From: Tesla List <tesla-at-pupman-dot-com>
> Original Poster: "Jim Lux" <jimlux-at-jpl.nasa.gov>
> > I knew I had this somewhere, but it took me a while to find it. There is
> > way
> > to change 2 phase power to 3 phase using only two transformers! It is
> > called a Scott transformer, and was used by power companies to go from 2
> > phase to 3 phase or 3 phase to 2 phase power. You do not have the puny
> > power limitations of capacitor systems, nor do you have to use a large
> > motor/generator setup. I found this in my 1939 Coyne home electrial
> The Scott connection requires true 2 phase power, with the phases 90
> degrees apart. Residential service is, of course, center tapped single
> phase. You can make the 90 degree phase shift with capacitors, but then,
> why not just make 3 phase power.
> For driving a power supply, an RC phase shift network like they use in
> welders has to be the way to go. No moving parts, etc. Sure, the phase
> balance gets terrible at low loads (why you wouldn't want to do this for
> running a motor), but for a power supply, it isn't even an issue. I'll
> figure out the equations and post them in the next couple of days.
I'm disappointed this won't work with existing power systems, but we find
and offer what we can to solve problems. Maybe next time I'll be more help!