Re: Variac turn-on surge solution

I think the problem is in the choice of manufacturer of circuit breaker.
It sounds like you have Square-D breakers.  These are extremely sensitive
to inrush currents from electronic equipment.  I have seen this with
Variacs and 1000W audio amps with toroid transformers.  The breakers that
are the most difficult to blow are the Federal Pacific.  The GE types seem
to be the best. I have had these and have never had any problems with
anything that I have ever plugged in.

If I were you, I would try to find another manufacturers breaker that will
work in your new box.  I would think that anything you do to lower your
inrush current can only reduct your available power.

Skip Malley

At 05:34 PM 10/27/99 -0600, you wrote:
>Original Poster: "Lau, Gary" <Gary.Lau-at-compaq-dot-com> 
>Dear List:
>I use a 15 Amp variac on my system, and after my house was upgraded from a
>fuse box to circuit breakers, I had a problem.  About half of the time when
>I turn on the variac, even though the knob was at 0%, the breaker would
>trip.  The reason for this is that when the variac was last turned off, the
>core may be left in either of two magnetic orientations.  If that
>orientation is counter to the phase of the AC voltage the next time it's
>turned on, the turn-on surge current can be huge, large enough to trip a 20
>Amp breaker.
>Hope this helps,
>Gary Lau
>Waltham, MA USA