Re: Run a 120v variac on 240???

John & all,
    I did a little test with a 165va 1.25A variac I have. I put 244v
on it with no load. It immediately drew 3A and continued to until it
got so hot that my workbench started smoking. This took about 10
minutes and there is a nice charred spot on my workbench now. More
then 2X the rated current with 244 on it no less for about 10
minutes. 732va in and it lived. I let it cool, it got so hot that
the plastic know was to hot to touch, and put 120v on it and it
still works fine. It's a tuff little variac. I can imagine if I put
a load on it that it would be toast now. So I'll try that later
today or Monday. After posting my first little thought I looked at a
240v 3Kva variac on ebay and noticed the core was a lot larger in
diameter then my 120v 2.5Kva variac. If the little variac starts on
fire while I'm abusing it I'll put up some cool pics. If it doesn't
I'll just have a few pics of the aftermath.
> >Hi everyone,
> >     I got to thinking again, shame on me, and thought what would
> > happen if I ran my 120v 20A Powerstat on 240v. It's rated at
> > so that would limit me to 240v -at- 10A. There is probably some
> > that I can't think of right now why this can't be done.  >>
> Shaun,
> If you apply 240 volts to a 120 volt powerstat, the core will
> and the unit will draw too much current and heat up, and probably
> burn up.  (I've never actually tried it, and I don't intend to.)
For a
> certain
> core size, there can't be over a certain amount of volts per turn.
For a
> given core size, a 240 volt variac is built with a greater number
of turns
> to take care of this.  This applies to any transformer, and
explains why
> you can't apply 240 volts to a 120 volt NST (for example).  (not
> toasting it anyway).
> Cheers,
> John Freau