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Re: capacitor safety gaps
Hi Roderick,
Did you read my posts about PE destruction testing? I have found that at TC
frequency a 500v/mil is a very acceptable value with a good safety margin
included.
So at 60 mil I would go for a 30kV rating. This will keep you on the safe
side. If you want to be really, really safe do the following:
a.) Make another capacitor, just like the one you already made, except use
smaller plates (width and length). You only need the 60 mil thickness really.
Now roll this cap and let her have it on a (reso tuned) tc. (run it dry and in
the dark). Keep making the safety gap wider and wider. You will find a
setting, where the cap starts to arc internally. Measure the safety gap
setting. Calc the aprox. voltage. Go down say about 5kv. This will give you an
absolute safety margin (because remember, you are running your test cap dry).
It is a little more work, but as you arenīt workin with messy oil and itīs
not another huge cap, I would go for it. This lets you rate the safety gap to
YOUR capacitor.
Coiler greets from germany,
Reinhard
Original Poster: RODERICK MAXWELL <tank-at-magnolia-dot-net>
I have just finished building my largest (and most expensive)
capacitor yet and I don't want to punch a hole through the dielectric.
The capacitor is 55nf using 60mil poly between the plates. How wide
should I set a safety gap across the cap to prevent overvoltage?
Talk about big and heavy it must weigh 50lbs!