[TCML] PFC question
drieben at comcast.net
Fri May 16 17:56:57 MDT 2008
I ran the specs of my medium PT powered coil through JavaTC
and came up with something like 675 uFd for suggested PFC.
I tied in (7) paralleled 100 uFd run caps in parallel with the
main input to the PT and the saturable reactor ballast. The
added 700 uFd actually caused the transformer/sat reactor
to draw about 40 to 45 amps with 120 volts input before I
even started gradually ramping up the voltage to the control
coil of the sat. reactor. The only "real" load was the insigni-
ficant SG cooling fan. Now what was really strange is that
as I cranked the input voltage to the PT/sat. reactor (not
the control voltage) to beyond about 140 volts, the current
draw suddenly begun to DECREASE and if I kept increasing
the voltage beyond this point, the coil would start to spit
out sparks without any voltage into the sat. reactor's control
coil. Normally, the PT cannot pass enough current to fire
the coil when there is zero voltage to the control coil of the
saturable reactor, even with 140 volts of input. Of course the
abrupt sparking would cause the current to once again increase.
Question - can anyone explain these effects and should I
only parallel the PFC with the input of the PT only and not
the main input to the PT and its ballast? Do PFCs really work
for non-shunted transformers in SG driven Tesla coil circuits?
The PT is a 120:1 (14,400 volt) 1.5 kVA @ 30*C GE instrument
transformer and the saturable reactor is rated at 12 kVA and was
originally paired with a 15 kVA, 240V/20 KV dry neon bombarder
transformer (which I in fact still have ;^). Sorry but I don't really
know the exact inductance ratings of the transformer or reactor.
The secondary coil is wound with about 28" on a 6.5" OD PVC
pipe with #22 AWG magnet wire. The primary C is .04 uFd driven
through an air-cooled stationary SG and the topload is a 6 x 30"
Thanks in advance for any advice,
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