Re: stacked poly cap

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <FutureT-at-aol-dot-com>

In a message dated 9/5/01 10:26:41 AM Eastern Daylight Time, tesla-at-pupman-dot-com 
writes:

> I was thinking of building a stacked poly cap using the HDPE sheets 
available 
> 
>  from McMaster-Carr. I wanted to use the 1/16" thick sheets. They are 
pretty 
>  cheap ($1.67 I think.) Does anyone know what voltage the sheets should be 
>  able to withstand? I haven't been able to find reliable information on the 
>  dielectric strength of HDPE. Almost everything I have seen has a had a 
>  different value for the dielectric strength. Also, I was wondering if 
> someone 
>  could give me the formula for calculating the capacitance of a plate cap.
>                                      Justin

Justin,

such a cap can handle a 9 or 10kV NST.  It may handle a 12kV NST,
but it may fail, *depending* on your gap spacing if you use static
gaps.  Many folks have had these caps fail with 12kV and
15kV NST's.  When I use these caps, I put two of them in series, for
12 or 15kV systems, and I've had no failures.  Of course the peak
voltage from a 12kV system can be much higher than 12kV, but
I'm taking that into account.

John Freau