Re: capacitor safety gaps

• To: tesla-at-pupman-dot-com
• Subject: Re: capacitor safety gaps
• From: Doug Brunner <dabrunner-at-earthlink-dot-net> (by way of Terry Fritz <terryf-at-verinet-dot-com>)
• Date: Tue, 06 Oct 1998 08:09:05 -0600
• Approved: terryf-at-verinet-dot-com

If you want to cut it close, set the gap at .9 inches. That'll break down,
in most locales, at precisely 27 kV, which is your cap's rating (poly
breaks down at 450V/mil). To be safe, set it at .8 or so. However, I don't
have experience with this, so don't trust me too much!

If you want to know how I calculated it, I took the 60 mil figure,
multiplied it by 450V/mil, divided it by 30V/mil, and got 900 mils or .9".

Dg: gap distance in mils
Wd: dielectric width in mils
Bd: dielectric breakdown per mil
Bg: gap breakdown per mil (varies with atmospheric conditions)
Dg = Bd * Wd / Bg

Tesla List wrote:

> 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!
>
>                                  Frankensteins Helper
>                                         Max



--
           --Mr. Postman (Doug Brunner)
                <dabrunner-at-earthlink-dot-net>

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