RE: caps

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

Original poster: "Lau, Gary by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Gary.Lau-at-compaq-dot-com>

I think you may have missed my point.  I fully agree that there is no
"universal" cap that is good for all applications.  My point was that
one cannot conclude that a cap with an AC voltage rating is good for TC
use, or that one with only a DC rating is not good for TC use.  Only by
looking at the dielectric type, plate construction, and dV/dt ratings
can a cap's suitability be judged.

As an aside, I have to wonder about Maxwell's recommendation about not
using pulse caps for DC applications.  I wonder if the concern is that
an unequal DC bias might form across the series-connected elements of a
Maxwell cap, which might be similar in thinking to the use of 10M
resistors across MMC caps?  But then, with the exception of DC coils,
MMC's are charged on a 60Hz AC schedule...

Gary Lau
MA, USA




>Original poster: "Crow Leader by way of Terry Fritz
<twftesla-at-qwest-dot-net>"<presence-at-churchofinformationwarfare-dot-org>

 >> Original poster: "Lau, Gary by way of Terry Fritz
<twftesla-at-qwest-dot-net>"
 <Gary.Lau-at-compaq-dot-com>
> >
>> Don't dismiss a cap just because it has a DC voltage rating.  The
only
 >> voltage rating on the label of a Maxwell pulse caps is a DC voltage,
and
 >> these have been known to be useful in Tesla coils!

> Maybe those ones are "ok" but a DC cap is not an AC cap.

 >> The problem is that "AC" by itself is not at all specific.  A motor
run
 >> cap has an AC voltage rating because it's assumed that it will run
at
 >> 50/60 HZ -at-100% duty cycle.  For anything else, are we talking about
60
 >> Hz and 100% duty cycle, 100KHz at 100% duty cycle, or 100KHz at some
 >> small duty cycle?  The same cap would have very different ratings
for
 >> these different applications.

> There would be no "same cap" for motor run applications and 100kHz.
Low
> frequency caps are cheaper to make, and that is how motor run caps are
> built. There is no univeral capacitor that is magic for all
applications.
> You will notice that Maxwell Labs warns against using their pulse
>capacitors
> as entended use DC filter caps evn though they might seem rough and
tough
> enough for the "ligher" job.
>
> KEN