Re: How could a pulse cap operate in TC?

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "father dest" <dest@xxxxxxxxxxx>


he-he-he - give me some time to think about "100 bps vs 500 bps" - too much 
information,
and now - comments about caps :-)

Original poster: Terry Fritz 
<<mailto:teslalist@xxxxxxxxxxxxxxxxxxxxxxx>teslalist@xxxxxxxxxxxxxxxxxxxxxxx>

>It is purely a function of the RMS current which usually has to be
>calculated with circuit simulators.  It used to be about 8 amps but there
>is a new dielectric out now that does far better so 13.5 amps is the number
>for CD caps.

ok, see - 942C20P15K gives us 13.5 a - at what frequency?
let the loses be 0.0005, on 10 khz cap`s resistance would be 106.16 ohm, 
then loses
in in would be 9.67 watt - the cap couldn`t face such heat in any case.
in datasheet 
(<http://www.cornell-dubilier.com/catalogs/PULSE-942C.pdf>http://www.cornell-dubilier.com/catalogs/PULSE-942C.pdf) 
they don`t mention
the frequencies, where rms current was measured - maybe they were measuring 
at 500 khz,
where reactive power is 5 times less, than at 100 khz.
it`s useless to write rms rating without its frequency!

>5. Peak voltage - For Tesla coils, we can use the DC rated voltage value
>and ignore the AC voltage rating.

are you sure? i can imagine 100  942C20P1K caps for 2 kw 100 bps tc, but if 
2000 volts
is maximum peak-to-peak rf voltage, then i need 400 caps - it`s stupid - so 
for the price, so
for the size of MMc :-)

>Now days, with our help, the data the manufacturers give is very very
>good!!  They are better at testing and specing them than "we" are now ;-))

i don`t think so - in datasheet 
(<http://www.cornell-dubilier.com/catalogs/PULSE-942C.pdf>http://www.cornell-dubilier.com/catalogs/PULSE-942C.pdf) 
they
didn`t mention neither the frequency, at what rms was measured, nor the 
temperature resistance
"dielectric-air" or the maximum power dissipation.

>The caps should not get hotter than 10C above
>the air temperature or the dielectric deep inside may start to melt.

let`s imagine i`ve calculated loses power - how could i convert it into 
overheating?
where did you take the values of

"Ko = Small Capacitor Thermal Dissipation Factor (? C / Watt)"
<http://hot-streamer.com/TeslaCoils/MMCInfo/MMCPower4.html>http://hot-streamer.com/TeslaCoils/MMCInfo/MMCPower4.html

?

>A lot of work has gone into it.  We try to make it simple for everyone with
>charts and programs.

and where are (except those on your site) these charts and programs? maybe 
a link?

p.s.
942C20P10K -  nowadays do we have something better by the price/quality value?

p.p.s.
2 kw 942C20P10K  mmc`s size is too big, what should i do at 5 kw? at 10 kw?
maybe it`s better just to find a maxwell and don`t bother? something like 
37330 from here:
<http://www.gaep.com/series-s-ss-de-capacitors.html>http://www.gaep.com/series-s-ss-de-capacitors.html
:-)

---

Your not coiling unless your blowing capacitors! Then when you get things
worked out to where the capacitors stop blowing, you start blowing 
transformers.
(c) Richard Quick 11-03-93 20:42