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Re: new caps (fwd) (comments on PVC) (fwd)
---------- Forwarded message ----------
Date: Sat, 17 Jan 1998 11:23:02 -0800
From: Jim Lux <jimlux-at-earthlink-dot-net>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: new caps (fwd) (comments on PVC)
> PVC pipes are rather excessively thick for this purpose, and as
consequence
> you get low capacitance per volume. The thickness of a PVC pipe can
sustain
> several million volts, but you need only a few tens of kV. PVC is also
> rather lossy at high frequency, and has significant surface conductance.
large PVC pipe also often has voids in the pipe wall or is even a very
dense foam. This is particularly true for ABS drain pipe by the way.
Furthermore, PVC pipe is often not made of virgin PVC (sand off that pretty
white (bleached) outer coating, and oft as not, the actual pipe is grey
inside), and may have conductive impurities. After all, they are making the
stuff as pipe not as an electrical insulator, so all they care about is
it's structural properties, not its electrical. There is virgin PVC pipe
available for the food industry, but I suspect it is more expensive.
>
> > i cant inject oil into them however as this would risk shorting the
caps
> > so i figured id run em dry. they work fine but i have 2 ques. 1 when i
> > fire em i hear the normal corona humm but also some random clicks. its
> > not shorting i know. also how would i figure how much im losing with
> > these caps. ive got 1800 watts at my disposal (120 v -at-15 amps max) and
i
> > wanna use alot of em
>
> Probably you can eliminate most of the corona and clicks by varnishing
the
> pipes with polyurethane varnish. Solves the problem with surface
conductance.
> I have made some Leyden jar capacitors in this way.
A good combination of PVC for structural strength (such as it is: don't get
it warm) and polyurethane for insulation....