Re: how many geek group caps?

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

Original poster: "Dr. Resonance by way of Terry Fritz <teslalist-at-qwest-dot-net>" <resonance-at-jvlnet-dot-com>


It depends on how "hard" you want to run your PT.  PT's are not current
limited and external inductive reactance is required to limit the PT's
current.  PT's in Tesla coil duty (60 sec. a run or less) can usually be run
up to 3.6 kVA without problems.

At 14.4 kV a good value would be 14 x .15 MFD 2 kV MMC units in series for
each string so the rated voltage would be .0107 MFD at 28 kV DC peak for the
single string.  Strings are then connected in parallel to achieve the best
match for your circuit parameters.

If the PT's current is set at 180 mA output (using a climbing arc to set it
up) then a good match is .03 MFD at 28 kV, ie, 3 strings of 14 pcs/string
connected in parallel.  Without power factor correction caps the PT will
pull 20 Amps on the pri. side, so I would advise using approx 80 MFD power
factor correction cap on primary side of PT (4 pcs x 20 MFD 240 VAC rating
connected in parallel).  This will reduce current draw enough to allow you
to run your RSG on the same circuit.

Use a 9 inch dia. RSG rotor w/ 6 electrodes on a 8 in. dia. circle (8 pcs
1/4 inch tungsten rod x 1.5 in. long) running at 1800 RPM (185 bks/sec).
Use a variable speed DC motor so you can adjust the bks/sec. to get best
match.

8 in. dia. sec. coil x 40" long winding of 22 AWG 200 degree C. wire with 20
turn pri tapped around 15 turns  will produce a nice 60 inch output spark.
Sec. coil is elevated above primary plane approx 3 inches.

Some experimenters only rate their cap strings at the value of the Erms of
the transformer but this is asking for trouble.  We always rate the cap
string at twice the Erms rating of the transformer and they last for many
years.  Wire two 5 meg 1/2 watt resistors in series across each cap in the
string.

Dr. Resonance

Resonance Research Corporation
E11870 Shadylane Rd.
Baraboo   WI   53913
 >
 > How many geek group caps would you say i would need for a 14.4Kv 1.5KVA
 > potential transformer?
 > thanks
 > Adam