Re: Continued Problems (fwd)
---------- Forwarded message ----------
Date: Wed, 6 May 1998 10:54:47 EDT
From: Esondrmn <Esondrmn-at-aol-dot-com>
Subject: Re: Continued Problems (fwd)
In a message dated 98-05-03 17:45:32 EDT, you write:
Let me preface this by stating that I am a relative "newbie" and I have not
worked with a pole pig yet, so it could be my lack of understanding causing
your cap to stand out like a sore thumb to me. You state that you are using
a 0.025 uF 15kv (A.C. or D.C. rating?) cap in conjuction with a 5kva 14,400
volt pole pig.
My understanding states that 14,400 (eff) x 1.414 (pk) x 2 (pk to pk)
would equal 40,723 volts peak to peak and when tossed into a coil, the
returned peaks would greatly exceed even this.
Mike Hammer has stated that above 12kv you should use three caps in series
in oorder to limit the high voltage strain across each individual cap. I am
just starting to understand why.
I believe at 5kva, you are putting out around 0.347 A -at- 14400 volts which
would need a total capacitance of around 0.064 uf at about a 60kvdc rating.
I am sorry that I do not understand the effect of the current control
method that you are using has on Xc but it seems that Xc would change as you
change the current output. If this is so, the capacitance would need to
change according to the current output. Perhaps someone can jump in and
explain this to me.
Your 0.025 uf cap should work best at a current output of 0.140 amps , or a
little less than half of your full 5kva output.
Your safety gap is firing when the voltage reaches the breakdown voltage of
the gap. I am not sure what 5/8" is voltage wise, but if someone said use
5/8" I would stick with it. By increasing the capacitance, you can increase
the current throughput without changing the voltage (i.e. causing the safety
gap to fire).
Just my semi-informed 2 cents!! Bill Turbett
P.S. I do not know what you are spending on commercial caps, but if it is
anywhere near the prices I have seen you would be better off building your
If you are interested in building your own or in having one built, I am
presently designing an easily made, modular and variable capacitor
specifically for tesla coils. email me directly ( Fxphoto-at-centuryinter-dot-net )
for details as I would rather not make an untested design public.
A couple of people have commented on the rating of the Condenser Products cap
that I am using. I was incorrect in stating a 15 kv rating. It is rated at
20 kv RMS and C.P. says it was designed for a maximum of 34 kv peak including
safety. It is designed for this purpose and should work ok with a 14.4 kv
supply. I will keep you posted. I have built three home made caps and may
build some more some day.