12" coil first light (7 foot arcs!), amazing mmc, problems, etc!!!

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Original poster: "Mr Gregory Peters by way of Terry Fritz <twftesla-at-qwest-dot-net>" <s371034-at-student.uq.edu.au>

Hello all,

Well, I couldn't wait. I jusy HAD to fire my new 12" pig powered coil. I
have just made my sync gap (400/200/100 BPS) and am waiting for a
truckload of mmcs to arrive. But in the meantime, I just had to fire my
coil!!! So I got my old MMC, which has 4 strings of 8 arcotronics
1500vdc, 0.1uF capacitors. I usually wire these in series/parallel for
24kV peak and 0.01uF. So I tried this with my 12" coil, but didn't have
enough primary to get a tune. So I figured "bugger it, I'll just put the
strings in parallel, it was cheap anyway". This gave me 12kV peak and
0.04uF. Believe it or not these actually took the full 12.5kV RMS output
from my pig with no problems. They did get pretty warm, but not a single
failure. Boy these caps are tough! Anyway, in a VERY rough state of
tune, and the gap not yet properly syncd in at 400BPS I was getting EASY
7 foot point to point arcs. Total power draw was 15-20 amps from the
240v outlet. I ran it for a few minutes, then, nothing....... The earth
leakage detector had tripped. I reset it and the coil ran fine for about
2-3 seconds, then the detector tripped again. I don't know what is going
on. I have had this problem before. My power cabinet seems to be
electrically sound (it will run a jacobs ladder fine, and tonight was
the first time I have used it with a coil). It only happens when running
a big coil. I can't find any arcing to any house wiring or anything. Is
it possible that the coil is inducing a current in nearby house wiring?
I don't know what is going on. I had this problem the last time I fired
my six inch coil. There are no shared parts with the old 6" coil and the
new 12" coil except the arc welder ballast, which leads me to suspect
the welder. Maybe it gets warm and the insulation fails? It's pretty
old. Any tips would be great!!

Cheers, 

Greg Peters
Department of Earth Sciences,
University of Queensland, Australia
Phone: 0402 841 677
http://www.geocities-dot-com/gregjpeters