Re: variac voltage out (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Thu, 14 Jun 2007 05:05:18 -0400
From: Dave Pierson <davep@xxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: variac voltage out (fwd)

 
>Maybe for a few seconds before it overheats and gets destroyed.
>I believe that the impedance of a transformer's primary is carefully
>matched to the input voltage.  If your voltage is too high the current
>flowing through will be too high and overheat the transformer.  If it's
>too low, not enough current will flow to provide enough current to the
>secondary output.

>Correct me if I'm wrong. :-)
     Maybe a tad overcautious.  I'd not try doubling up, but, depending on the
     transformer, rating, etc, might be doable.  I'd expect lots of 'stray turn
     on surge' circuit breaker/fuse activity.

     Depending on details of application, power levels needed, (and what in the
     junk box) I might look at whether a 110/200 transformer on the OUTPUT of
     the variac would be applicable, pondering any stray transformers with
     universal primaries (jumperable for 110/220....) 

>>      can you put 240V through a 0-140V variac to get 280 out, or will it 
>> melt or saturate or any other bad things happen to it?

    best
     dwp