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Re: Ballasting

Original poster: "Gregory Hunter by way of Terry Fritz <twftesla-at-qwest-dot-net>" <ghunter31014-at-yahoo-dot-com>

I've never used a variac as ballast, so I can't speak
to that. However, I recently tried the welder ballast
setup with a cheap, 230A AC stick welder and a 5KVA
pole transformer, and it seems to have improved the
efficiency of my Tesla coil sytem--I get longer sparks
with less current.  I can't quantify this improvement
as don't yet have a suitable panel meter, and the
digital clamp-on ammeter I was using gave ambiguous

I've tried it with the welding leads both open and
shorted, and it works pretty good either way.  The
shorted condition draws lots more current and pushes
longer sparks from the TC.  Although the welder has a
scale on the front that goes from 60 to 230A, I have
not yet tried it any higher than 90A due to lack of
guts.  The TC output gets really frantic as the
current goes up, and I'm concerned that a rogue
streamer is going to reach across the garage & pop me
if I turn the juice up any higher.



--- Tesla list <tesla-at-pupman-dot-com> wrote:
> Original poster: "Steve White by way of Terry Fritz
> <twftesla-at-qwest-dot-net>" <slwhite-at-zeus.ia-dot-net>
> I am facing that thorny issue when using a pole
> transformer and that is how to
> ballast. I have read that one can ballast a pole
> transformer with a suitably
> rated variac configured as a variable inductor. I
> have also read that this
> method is not ideal because the variac core does not
> have an air gap and is
> thus liable to saturate. Also, since the maximum
> number of variac wire turns
> may not be used, this does not fully utilize all of
> the core. I have read that
> other people use this method and it works fine. I
> have also read that using a
> constant-current arc welder is an ideal ballast. If
> so, how is it connected? Is
> the secondary left open or shorted? I assume that
> the pole transformer power is
> drawn through the arc welder primary in a series
> connection. Facts, not
> conjecture, would be greatly appreciated.

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