Re: variac size and flashover
Subject: Re: variac size and flashover
From: Terry Fritz <twftesla-at-uswest-dot-net>
Date: Fri, 12 Nov 1999 22:30:47 -0700
At 04:38 PM 11/10/1999 -0500, you wrote:
> 2 questions for the gurus:
> 1) How big a variac do i need? 5 amps? 15 amps? I'm going to be
> running a 12kv 60ma NST.
My 12/60 neon draws about 12 amps. With PFC caps (200uf) that drops to
about 7.5 amps. A 10 amp variac is just right. A 5 amp is probably
pushing things too much since it may saturate even if you have PFC caps.
also the brush my fail. A 15 amp would be bullet proof.
> 2) What's the recommended distance between the first turn of the
> primary and the secondary to prevent flashover? I was thinking 2",
> (for a 6" secondary) but now i'm wondering if that's too much. . .
As close as you can get without sparks racing up and down the secondary
coil (racing arcs). Or, without the secondary arcing to the primary. 2
inches is probably pretty close but I would make it easy to adjust as
needed. Better too far than too close.
> paul mathus