Re: 200:1 Potential Transformer

["Tesla list" <tesla-at-xxxxxxxxxx>]

Original poster: "Metlicka Marc" <mystuffs-at-orwell-dot-net> 



Tesla list wrote:

> Original poster: "Barton B. Anderson" <tesla123-at-pacbell-dot-net>
>
> Hi Jason,
>
> Smart question (hope I can give a smart answer):
>
> Higher voltage at the cap can be very desirable, but over-voltage is a
typical
> failure for caps in disruptive high voltage tesla service. How far you
push the
> tranny depends on two things. (1) The cap rating and (2) your over-volt
safety
> factor. Periodially, the cap may see Vp-p voltages as well as high
> transients. At
> 24KVrms your looking at a cap rating of 24kv x 1.414 x 2 = ~68kv minimum! A
> typical safety factor is 3 times the cap rating. For example, if a cap is
> rated at
> 60kv(AC), then don't pump in less than 20KV at the tranny. Some like to
> extend the
> factor higher than 3 depending on their experience and/or fear of loosing a
> high
> dollar cap. Safety gaps of course help to prevent popping a cap. Don't rely
> on the
> safety gap to limit the cap voltage. Rely on your design.
>
> Take care,
> Bart

hi jason,
this info that bart gave is very sound. in using my 300-1 pt the most i
have run
through it in tc service is 100v. this was only with home made flat plate caps
rated at 99kv minimum, with my present pulse cap that is rated for
55kvdc-at-52nf i
cringe every time i push the button at 72v in, giving 21600v and 31kv p-p.
the fact
that this is a good cap has been proven in that it hasn't died yet, but
that is a
big yet!
since it is plate rated at 110v out from 33kv in, i could rely on it
providing 30kv
in tc service dependably but the caps are a deciding factor for me, i have some
33kv dual 48nf pulse caps that i got off of a kind member of the list, but
until i
get my sync. rotary finished, i will not try them.
as a suggestion i would say, start with 70v or so  to get things rock solid and
then go to what you can in the way of caps.
marc

>
>

snip