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Re: Tube coil capacitors
These caps are probably fine (economical) for tube coilers operating at
much lower voltages than typical disruptive TCs. But they don't appear
very economical for the latter.
Based on Terry's experience, let's assume the caps can actually withstand
twice their rated voltage. So each cap is .0056 uF at 3200 VDC. If we
string 16 in series, we get .00035 uF at about 53 KV DC. So a hundred of
them would give us 6 times that or .0021 uF. For most coils we would need
an order of magnitude more capacitance, or about 1000 caps in
series-parallel. So the cost would be probably $600 per 1000, based on the
$69.75 per hundred price in the posts below. That's expensive, and a lot
of soldering!
Bottom line, probably more economical to buy a Maxwell or other commercial
pulse cap. Comments?
--Steve
----------
> From: Tesla List <tesla-at-pupman-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: Re: Tube coil capacitors
> Date: Thursday, February 18, 1999 5:18 PM
>
> Original Poster: Terry Fritz <twf-at-verinet-dot-com>
>
> Hi Dave,
>
> The ECWH(V) series on page 324 of the Jan-Mar. catalog look great. They
> were not available when I bought mine (pg. 322 P3521-ND ECQP(U)). The
> things to watch for are dissipation factor and the word polypropylene.
> These are both 0.1% at 1kHz. The suggested applications of "high
voltage,
> high frequency, and high pulses" is another clue that they are made to
> deliver high currents quickly with low loss. Just the ticket for our
> stuff. These caps are probably better than the old micas. One may have
to
> figure out which cap gives the needed value for the best price, but
either
> series should work very well.
>
> Terry
>
>
>
> At 09:34 AM 2/18/99 -0500, you wrote:
> >Terry,
> > Your testimony is encouraging. I really like the idea of combining
many
> small
> >value caps to produce just about any value desired. Let's make sure
we're
> >talking about the same thing. These caps are found in Digikey's online
> catalog
> >at http://info.digikey-dot-com/EC/V3/324.pdf (Don't have their current paper
> >catalog) and are called "High voltage Metallized Polypropylene Film
> >Capacitors"--ECWH(V). The 1600 Vdc, .0056 uF caps sell for $69.75 for a
> hundred.
> >
> > Are we on the same page?
> >Dave
> >
> >Tesla List wrote:
> >
> >> Original Poster: Terry Fritz <twf-at-verinet-dot-com>
> >>
> >> At 05:10 PM 2/17/99 -0500, you wrote:
> >> snip........
> >>
> >> > I've considered one option: Digikey has Panasonic polypropylene
caps
> >> >rated at .0056 uf, 1600 vdc. They're fairly inexpensive, so multiple
units
> >> >could be purchased and series/parallel combined to produce just about
any
> >> >value needed. The ability to vary capacitance is of obvious value.
> Also, I
> >> >wonder if the use of polyprop units will result in a higher circuit
Q
> over
> >> >that which would be effected by using Mica caps? snip....
> >>
> >> Other things have pulled me away from my many caps primary cap project
but
> >> I wanted to say that those Panasonic poly caps have performed with
> >> excellence for me! They run cold and have very high margin. I think
> >> mixing them together to get a desired value will provide a very good
and
> >> reliable device! The 630 volt ones I use break at around 2400 volts.
When
> >> I take them apart (I am a failure analysis engineer), their internal
> >> construction is very good. I would not hesitate using them for any TC
use.
> >>
> >> Terry
> >
> >
> >
> >
>