Re: 240 vac variac observation

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "davep by way of Terry Fritz <twftesla-at-qwest-dot-net>" <davep-at-quik-dot-com>

Tesla list wrote:
> 
> Original poster: "Allanh by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<allanh-at-starband-dot-net>
> 
> If you are speaking of normal house wiring, you drawing
> of the 240AC is wrong. A 240 variac varies each phase of the line
> voltage in reference to neutral. That means 120
> volts AC on each side of nutral 180 degrees out of phase.

	In phase.
	If out of phase, they would sum to zero across the
	two hots....

	Hint:  Measure phasing differentially....

	best
	dwp
=====================================================================
> ----- Original Message -----
> From: "Tesla list" <tesla-at-pupman-dot-com>
> To: <tesla-at-pupman-dot-com>
> Sent: Wednesday, February 06, 2002 6:43 AM
> Subject: 240 vac variac observation
> 
> > Original poster: "Yurtle Turtle by way of Terry Fritz
> <twftesla-at-qwest-dot-net>" <yurtle_t-at-yahoo-dot-com>
> >
> > I'm probably stating the obvious to most of you guys,
> > but this is something I recently discovered, regarding
> > > 120 volt variacs.
> >
> > In my neck of the woods, neutral = ground.
> >
> > With a 120 volt variac, we are varying the output
> > potential relative to neutral. No problem. See below:
> >
> > --------)
> >         )
> >         )<------  0 - 120 vac
> >         )
> > 120 vac )
> >         )
> >         )
> >         )
> > --------)--------  common
> >
> > -----------------  ground
> >
> >
> >
> > In a 240 volt variac setup, we are varying the
> > potential relative to one phase, from 0 to 240 volts.
> > This results in an unsymmetric 0 - 240 volts relative
> > to neutral/ground. See below
> >
> >
> > --------)
> >         )
> >         )<------  0 - 240 vac
> >         )
> > 240 vac )
> >         )
> >         )
> >         )
> > --------)--------  common
> >
> > ------------------ ground
> >
> > For example, I have a 34 kV DC PSU which wants 208
> > vac. If I feed it from my big variac, one leg will be
> > at a higher potential relative to neutral/ground, than
> > the other.
> >
> > Perhaps that's not a problem, but it might be for
> > some.