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Re: Unexplained arcing current
There WAS a resistor between the bypass capacitor and the gap. The
two 450pF bypass caps were each across the NST terminals and ground, and
the two 1.6K/113W resistors were from the NST terminals to the main gap
terminals.
I believe this situation where the tank was disconnected resulted in MUCH
hotter resistors than in normal operation. I think the explanation that
I gave where the bypass cap energy is dissipated in the R's adequately
explains the heating. The same thing occurs in normal operation, but
since the BPS is so much lower, the additional power from this is not
that significant. If I assume my main gap fires at 25KV 150 times per
second, my bypass caps would only contribute about 10.5 Watts to the two
resistors.
Regards, Gary Lau
Waltham, MA USA
>Original Poster: "B**2" <bensonbd-at-erols-dot-com>
>
>Hi Gary, All,
> What happens when you put a resistor between the bypass capacitor
>and the gap?
>>Original Poster: Gary Lau 25-May-1999 1022 <lau-at-hdecad.ENET.dec-dot-com>
>>
>>I believe I've figured out why my resistors get so hot. Well, almost.
>>
>>Recapping, with my tank circuit disconnected so that my 15KV/60mA NST
>>just fires my 0.36" static gap through my RC protection network, the
>>series resistors (1.6K/113W non-inductive film) get hot very quickly, but
>>if I disconnect the 450pF bypass caps, they do not.
>>
>>I realized that with my tank cap no longer in place, the bypass caps will
>>charge many, MANY times per mains half cycle. I quick simulation showed
>>that if the static gap were set to 15KV, it would charge and discharge
>>128 times per half-cycle. The RMS current through the resistors is over
>>250mA! That will do it!
>>
>>Only problem is, I also have this hot resistor problem to a similar
>>degree when my tank circuit is in place and the bypass caps may only
>>charge the same number of times as my main cap does, a couple of times
>>per half-cycle at most. Still looking...