Re: High Voltage / Current Coil

[Tesla729-at-cs-dot-com (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

Hi Cameron,

I am responding to your question on the Tesla list about building a
Tesla system for your 15 kVA pole pig. I will also try to respond to
your inquiry on the list, but the last couple of responses that I have 
sent to the list have never shown up on the list. So if you see this
response both in your personal mail and on the Tesla list, you'll know
why.

There is really no tirck to using a 15 kVA pig as opposed to using
a 10 kVA or even a 5 kVA for that matter. the bottm line is that a
pole pig is a non-current limited poiwer xfmr that is very conserva-
tively rated and it must be externally ballasted for Tesla service. A
typical pole pig can easily and safely provide 2-3 times its name-
plate rated power for the intermittent Tesla coil service. I use a 225
amp Lincoln arc welder only to ballast my 10 kVA, 14.4 kV pole pig
for my large Tesla system. I simply place the input (240 v) side of
the welder in series with the 240 v input side of the pig. The output
leads of the welder are kept shorted and I usually keep the ampe-
age selector switch on the welder -at- 150 amps. With this setup, my
coil draws around 8 kVA with an 82.5 nF tank cap, and throws very
loud and bright 8 to 10 ft. sparks!

There is no reason that this same welder ballast setup shouldn't work
just the same with your 15 kVA pig. The only thing that you may need 
to do differently is to use a larger primary cap (say 100 to 150 nF) and
go ahead and set your welder ballast -at- 225 amps so you can use more 
of the available powere from your larger xfmr. Remember, with your larg-
er xfmr, you can always limit your power output down to your specific
power needs but you will always have more available power when you
need it. The analogy is similar to driving a Ferrari Testarosa. You can
drive it thru a school zone at a legal 15 mph just as well as driving it
down the autobahn at 180 mph! As a matter of fact, I recall seeing a
coil web page that showed a medium-sized system throwing what ap-
peared to be 4 to 5 ft sparks. The amazing thing was that its power sup-
ply was a 25 kVA pole pig! I think that's rather extreme and I compared
it to placing an Indy race car engine in a go-cart, but I think this does
emphasize the point that I'm tyring to get across.

If you have anymore questions, I would be glad to try to answer them,
if I can. If you'd like, I can send you some more detailed specs on my
large Tesla system (Medusa). Take care.

                                                    Keep it 'a Sparkin,
                                                    David Rieben