Re: Polyester Film Capacitors

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

Original poster: "Barton B. Anderson by way of Terry Fritz <twftesla-at-uswest-dot-net>" <tesla123-at-pacbell-dot-net>

Hi Terry,

I run CSI 60kv polystyrene pulse caps and have yet to warm them in pig usage. I
don't run at long lengths, but they've seen lots of usage over the past 3
years.
Dimensions are 3" x 17" with large 3/8" bolt/ 5/8" nuts (the good stuff) at
each
end. When first picked up, I've always been curious to see these get warm, but
they don't. I check for this during all runs.

Take care,
Bart A.

Tesla list wrote:

> Original poster: "Terry Fritz" <twftesla-at-uswest-dot-net>
>
> Oops!  The dissipation is 0.0007 not 0.07 so it only runs 7 times hotter :-)
>
> Cheers,
>
>         Terry
>
> ----------------------------------------
>
> Hi Duncan,
>
> Polystyrene is alive and well and is commonly available as a capacitor
> dielectric.  However, the newer films are much more popular and are getting
> designed in as just the defacto standard.  Polystyrene's dissipation factor
> is 0.07 compared to polypropylene at 0.0001  That means they would run 700
> times hotter in our favorite application ;-)  There are many high voltage
> films out there, but we need super low dissipation factors.  Such caps also
> have high dV/dT and low inductance which we love too.
>
> Cheers,
>
>         Terry
>
> At 03:49 PM 3/27/2001 +0100, you wrote:
> >Hi All!
> >
> >
> >
> >>Polypropylene caps are the lowest-dissipation high-voltage
> >high-current
> >>caps out there
> >
> >They probably are, but I can't help wondering . . .
> >
> >Purely out of idle curiosity, has anyone ever seen high voltage high
> >current rated polystyrene caps?  Based on the dielectric properties of
> >polystyrene they ought to be pretty good too.  I have an illustration
> >in a book from 40+ years ago showing metal-cased polystyrene caps of
> >generous dimensions with the usual massive ceramic standoffs on them
> >and evidently intended for HT valve circuitry, but the British company
> >which made them (TMC in Orpington) no longer exists.  Just wondered if
> >anyone still produces such things.  The only polystyrene caps I've
> >seen recently are the small signal, low loss 160V jobs for your
> >average silicon circuitry.  I'm just wondering if there's a good
> >reason why we don't see hefty polystyrene caps, but from a polymer
> >chemistry view of things I can't think of a single reason why they
> >shouldn't be made.
> >
> >Dunckx
> >