Re: I don't understand (fwd)

---------- Forwarded message ----------
Date: Thu, 18 Dec 1997 20:58:25 -0500 (EST)
From: Charles Brush <cfbrush-at-interport-dot-net>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: I don't understand (fwd)

>Hi All,
>I have my Coil up and running with really good performance,
>(37" Discharges).  I am using 2 variacs. One for voltage
>control and the other for current limiting. Both variacs are
>rated at 30 amps. I'm using an EMI filter ran in revervse
>between the current variac and the PT, to help my home AC
>lines. I'm using a Westinghouse potential transformer, 100 to
>1 ratio, 15,000 Vac. I am also using 50,000 volt rated high
>performance neon sign wire running from the PT to the series
>spark gap consisting of 6 tungsten tig welding tips. I also
>have a safety gap right before the spark gap
>I placed an Amp meter in line after the current limiting
>variac and before the PT.  What I noticed is  that it takes
>about 17 amps for the spark gap to fire and the coil runs.
>Then the amp meter starts to peg and wildly swing back and
>forth.  ???
>*Is this what is called "kick back"?
>*Is this coming from the spark gap and is feeding RF or energy
>back through my power system?
>*Is this why chokes are used between the PT and the spark gap?
>Please help me understand?
>Thanks to all,
>Mark Bean

Hi Mark,

When your gap is conducting, it's acting like a dead short across your
transformer.  You'll see this when using a static gap with a high current
source like a PT or pig.  The gap simply doesn't want to extinguish after
the cap fires, resulting in a briefly shorted condition.  A rotary would
smooth this out, and it might be time to move up to one considering the
kind of power level you are running.  Also how is your current limiting
variac set up?  Variacs don't make very good current limiters without some
heavy modifications.  If you must use one, some resistance in series might
help mellow things out.  Good luck!


Charles Brush