Re: Stretch film capacitors?

To: tesla-at-poodle.pupman-dot-com
Subject: Re: Stretch film capacitors?
From: Tesla List <tesla-at-stic-dot-net>
Date: Thu, 27 Mar 1997 23:40:26 -0600
Approved: tesla-at-stic-dot-net
Subject: 
            Re: Stretch film capacitors?
       Date: 
            Thu, 27 Mar 1997 23:01:59 -0800
       From: 
            Bert Hickman <bert.hickman-at-aquila-dot-com>
Organization: 
            Stoneridge Engineering
         To: 
            Tesla List <tesla-at-pupman-dot-com>
 References: 
            1


Tesla List wrote:
> 
> Subject:
>         Stretch film capacitors?
>   Date:
>         Wed, 26 Mar 1997 23:32:30 -0500 (EST)
>   From:
>         "Kelly Seuferer" <seuf-at-freenet.tlh.fl.us>
>     To:
>         tesla-at-pupman-dot-com
> 
> I have been recently preparing to build a rolled poly capacitor and
> searching for a reasonable supplier of the poly sheeting.  Browsing
> through
> a plastics catalog, I noticed they had stretch film at a real cheap
> price.
> This is the stuff warehouses use to wrap up pallets of boxes with.  It
> comes
> in a variety of sizes (60, 70, 80, and 90 mil) and lengths.
> 
> Would this material be a suitable replacement for poly?  If so, how
> could I
> find out the dielectric constant and breakdown voltage?  If not, does
> anybody have a good source for poly sheeting?
> 
> Kelly

Kelly,

While this material IS polyethylene, it is much thinner than the 60 - 90
mils. This film is provided in 0.6, 0.8, 0.9, and 1.2 mil thicknesses.
This material probably would be prestty good... you'd just need to use
lots of sheets to get to the right overall thickness (typically 60 - 120
mils for operation in the range of 7500 - 15000 volts AC supply
voltage). The effective dielectric constant is about 2 due to looseness
and mineral oil filling the interface between the metal plates/foil and
the dielectric.

Regular polyethylene sheeting (like for drop cloths) is typically in the
range of 1 mil to 7 mils, and can be used to make very robust flat plate
or wound capacitors. Thicker material can also be purchased from
plastics suppliers. Most useful for rolled capacitors are sheets in 20,
30, 40, or 60 mil thicknesses.

Safe cappin' to you!

-- Bert H --