Re: MMC

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

Original poster: "Peter Lawrence by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Peter.Lawrence-at-Sun-dot-com>

Mike,
     handy formula for "resonance" sized cap is
        mA / kV * 2.652 => nF
for example 46 / 10 * 2.652 => 12-nF, so yes your .012-mF cap is resonant.

23 long strings is 434 volts per cap, which is way conservative. I've been
using 12 long strings on 9kV (750v/cap) since I got my MMC caps a year ago 
and have not had any problems, I'ld use 12 long for 10kV also, maybe 13 if
you're being overly careful, and 14 if you're superstitious!!!.

Cutting the strings down almost in half will almost double your cap, this
will be very LTR, and you might even want to experiment with only 4 or 5
strings also.

BUT, if you're burning out your transformers the most probable cause is
not having a safety gap. I run "resonance" sized caps and have not burned
out a transformer since I built and installed a safety gap.

Peter Lawrence.


>
>Hello,
>
>This is slightly off topic, but about a week ago I tried to post on a similar
>topic. I never did see it on the list so I thought I'd try responding to this
>one instead.
>
>I have a 4.25" X 25" coil driven by 2 10KV 23mA OBITS (60 Hz) in parallel for
>46mA. The cap is an MMC array consisting of 6 strings of 23 caps each that
>works
>out to .012 mfd and 27KV. According to my calculations (possible errors?) this
>is resonant with the OBITS. After burning out 3 OBITS, I am wondering if
>running
>in LTR mode would be a good idea. I can get .018 mfd and 18KV by removing 4
>caps
>from each string and using most of them to make a 7th string. Does anybody out
>there see disaster lurking in this idea? I'm not an experienced coiler and
>would
>appreciate any help from those who are.
>
>Thanks,
>
>Mike Kiser
>