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Small-ish polyprop. caps
I'm a newcomer, working on my first coil, even. I'm curious about using
these caps in a TC (which I seem to have a source for - not cheap, but good
things never are...) They are BHC Aerovox (RBPS Series) polypropylene caps,
designed to protect IGBT modules from large voltage transients. Besides being
high voltage, they are rather higher capacitance than other dry pulse caps
I've seen thus far, and also have rated dV/dt...
So, the biggest ones are 3 uF at 1000V, 2 uF at 1250V and 1.5 uF at 1600V.
They're rated at (dV/dt, in V/us) 400, 475, and 600, respectively, and at
peak voltages of 1400, 1600, and 2100 VDC respectively. I did some simplistic
calculations, I could just about use them at 200 kHz, 1000 V peak-to-peak and
be just a bit over 600 V/us at zero-crossing point. (They're rated for a
million pulses at 2 times rated dV/dt, 1000 pulses at 4 times, 100 at 6
times).
So this means, if my math went right, that I'd need at least 12 of them in
series to withstand operation with a 4 kV NST (my first setup), or perhaps
even more with two 2 kV MOT's (my possible next setup). But how will it be
in reality, the primary side I think doesn't have nice and clean sine-wave
signals. How long will it work without blowing :-)