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

To: tesla-at-pupman-dot-com
Subject: Re: Run a 120v variac on 240???
From: FutureT-at-aol-dot-com (by way of Terry Fritz <twftesla-at-uswest-dot-net>)
Date: Thu, 08 Jul 1999 16:47:05 -0600
Approved: twftesla-at-uswest-dot-net
Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme

In a message dated 99-07-08 05:29:47 EDT, you write:

<< 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 2500va
> so that would limit me to 240v -at- 10A. There is probably some reason
> 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 saturate,
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 without
toasting it anyway).

Cheers,
John Freau