Condenser Products Caps and max BPS??

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

Original poster: "Dave Hartwick by way of Terry Fritz <twftesla-at-qwest-dot-net>" <ddhartwick-at-earthlink-dot-net>

I've got 2 Condenser Products, TC503-34-300 0.05 mfd 20,000 VAC capacitors
(300$ each iirc). Purchased about 7 years ago, these units were designed
specifically for coil duty.

They've not been used in 5+ years and have been sitting in the same
horizontal position. Concerned about oil penetration after such extended
none-use, I talked to CP. Engineer Gene said to rotate them occasionally and
then bring the voltage up slowly. Sounds logical. Do you guys have any
experience with this?

Most interestingly, he told me that those caps are rated for a max break
rate of 120 BPS. I was not told this at the time of purchase. The problem is
that I had been using an air-blast gap and the break rate was/is unknown to
me. Gene suggested that the caps very well may have been compromised because
of possible excessively high break rates, as much as 4-5 cycle for that type
gap.

I wonder if this is the case? They were only fired for a total of maybe 20
minutes at about 3 KVA (5KVA 14.4 kV pole pig). I noticed no deterioration
in performance, but he suggested that any excessive internal
heating--related to the "Tab" configuration connecting multiple internal
series caps--could have resulted in damage that may not show up until one
fails catastrophically and explodes.

The 2 caps were run in balanced series config at < 100 KHz, the coil
producing about 5' sparks. Not very efficient for 3 KVA, at least measured
against the current Coiling state-of-the-art.

So what do you guys think of this potential damage problem? The only thing I
can do is try them again with a great deal of care. I guess I'll have to
encase them in a blast proof container of some sort. My hunch is that Gene's
caution was a bit overblown, but who knows?

I really thought these caps were supposed to be quite durable. They really
should have included literature specifically stating the operational
limitations, don't you think? Maybe I'll just go back to polyethylene salt
water caps, which surprisingly seemed to work nearly as well.
Dave Hartwick
Chambersburg, PA