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Re: Halloween night, CP cap {con,de}struction
Hi Chip, Bert,
> Original Poster: Bert Hickman <bert.hickman-at-aquila-dot-com>
>
> Tesla List wrote:
> >
> > Original Poster: Chip Atkinson <chip-at-pupman-dot-com>
> >
> <SNIP>
> >
> > My Condenser Products 0.025uF/20,000V tesla coil cap blew up! I'm glad it
> > was on the roof because it could have really hurt someone.
> >
> > Luckily, I had another CP cap and decided to try it too, since the coil
> > was going well and perhaps it was a fluke that it blew up. Nope! The
> > second one blew, and even more violently than before.
> >
> <SNIP>
>
> Chip,
>
> Sorry to hear about the death of your two caps! As you know, Condenser
> Products had apparently issued a recall for the batch of caps built as
> part of the last Tesla Builders group buy, apparently because of a
> manufacturing (or design?) defect. Do you happen to know which vintage
> yours were? CP applied some type of derating scheme to their caps, and
> claimed that the 20 KVDC ones should be good for use with a 14.4 kV pig
> source. However, if these were _actually_ 20 KVDC caps, this was
> probably not sufficient for the stress they'd actually see! I agree with
> John that they should actually rated for considerably higher voltage -
> more like 50 kV or above.
>
> Good luck on the home-builts!
>
> -- Bert --
The ratings on mine stated that they were good for 20kVAC. I read
that to mean 28kVDC. However, in TC use I will never push mine above
20kVDC. For two units that gives me 10J to play with. Not a lot, but
one of my coils is scoring a peak of 4-1/2 feet with barely 3J at
100BPS and that's with dry-fired poly to boot. At the moment, I'm
using mine for key experiments only where the best is demanded.
I bought two as that gives me a range between 50nF at 20kV and
40kV at 12.5nF which allows considerable latitude in primary L at
different frequencies.
Malcolm