Re: variac size and flashover

Hi Paul,

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.



>     thanks,
>     paul mathus