Re: A reVOLTing development.

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Dr. Resonance" <resonance-at-jvlnet-dot-com> 


Chris:

With a standard 12 or 15 kV, 60 mA, xmfr, we usually employ a twin spark gap
with 1/2 inch dia tungsten electrodes.  With electrodes this large the
quenching is very efficient and the gap has adequate cooling without a
blower or fan.

For caps we use MMC with a 2.5:1 ratio, so Erms = 15 kV, then Erms * 2.5 =
37.5 kV DC rating which leads to 37.5 kV / 2 kV per cap = 18.75 caps.  It's
safe to round off to 18 caps per string which equals .15 uF / 18 caps per
string = .0083 uF at 37.5 kV DC.  Two series strings of 18 caps in each
string are connected in parallel for .0167 uF at 37.5 kV DC.  This combo
will run for over 60 years without failure as long as you keep your spark
gap total setting within reasonable limits, ie, approx 0.200 inch or less.

For a 60 mA current source, .0083 uF * 2 = .0167 uF at 37.5 kV DC.  This is
a near perfect match for a 60 mA xmfr with Cbest = Cres value * 1.6.

Gerry's comments are right on target with regard to the peak current.  Take
care not to exceed.

Dr. Resonance

 >
 > Yes on the 16.7 nf, but be careful on the string of 9.  Nine is OK, I
think,
 > if each is rated at 3KVdc.   I use strings of 14 - 2KVdc caps and I feel
 > comfortable with that for a 15KVrms transformer (over 21KVpeak).  You will
 > find different opinions on voltage ratings amonst the group.  Also don't
 > exceed the peak current rating of the cap.  Total peak current (assuming
no
 > losses) will be:
 >
 > Imax = Vmax / sqrt (Lp/Cp)
 >
 > This current will split between the number of strings either equally (if
all
 > strings are alike) or unequally if the string capacitance differs between
 > strings.  For example, the current thru string 1 (of 3) strings will be:
 >
 > Ipeak_1 = Imax * C1/(C1+C2+C3)
 >
 > Gerry R.
 >  >
 >  >
 >  >
 >  >  > -----Original Message-----
 >  >  > From: Tesla list [mailto:tesla-at-pupman-dot-com]
 >  >  > Sent: Monday, August 02, 2004 9:31 PM
 >  >  > To: tesla-at-pupman-dot-com
 >  >  > Subject: Re: A reVOLTing development.
 >  >  >
 >  >  >
 >  >  > Original poster: "Gerry Reynolds" <gerryreynolds-at-earthlink-dot-net>
 >  >  >
 >  >  > Hi Chris,
 >  >  >
 >  >  > Cres = 10.6 nf
 >  >  > Cp for static gaps = 17 nf
 >  >  > Cp for SRSG = 30 nf
 >  >  >
 >  >  > Gerry R.
 >  >  >
 >  >  >
 >  >  >  > Original poster: "Christopher 'CajunCoiler' Mayeux"
 >  >  > <cajuncoiler-at-cox-dot-net>
 >  >  >  >
 >  >  >  > I'm using a pair of 15/30 NST's, paralleled.
 >  >  >  > So my limit would be????????
 >  >  >  >
 >  >  >
 >  >  >
 >  >
 >  >
 >
 >
 >