Dielectric Breakdown of Polypropylene

From:  Michael Nolley [SMTP:mhnolley-at-willamette.edu]
Sent:  Friday, June 12, 1998 9:58 AM
To:  Tesla List
Cc:  'Tesla List'
Subject:  Re: Dielectric Breakdown of Polypropylene

On Wed, 10 Jun 1998, Tesla List wrote:

> ----------
> From:  Brandon Shaw [SMTP:bshaw-at-monmouth-dot-com]
> Sent:  Tuesday, June 09, 1998 5:41 AM
> To:  Tesla-at-pupman-dot-com
> Subject:  Dielectric Breakdown of Polypropylene
> All,
>     I am in the process of constructing a plate cap  and need to know
> the
> breakdown voltage of polypropylene. I know that as the thickness
> decreases the
> breakdown voltages increases but have no way of getting a good estimate
> for how
> much of a safety margin I should build into my caps. I'd like to
> over-engineer these
> babies a little bit but on the other hand don't want to waste a ton of
> money.
>     I plan on using two layers of 2.4 mil poly between each layer of
> foil and building a number of sections that will will connected in
> series to obtain the proper voltage rating.
> Any help would be appreciated.
> Brandon Shaw
	I'm working on a similar project right now-- you can get the 
specs on poly in most of the texts on homemade caps.  With 2.4 mil you 
may have to wire 10-15 capacitors in series to have enough margin.  This 
is what I'm doing, although I'm not too excited about the prospect of 
spending my summer with aluminum foil and ziplocs...