We would remove these caps from the bank once they migrated outside a specific tolerance, typically 2-3 per year, and hopefully before an internal rupture occurred (bulging).
Sent from my iPhone
On May 20, 2017, at 10:15 AM, David Rieben <drieben@xxxxxxx> wrote:
Hi Bert, (and Terry, if you're still following this thread),
Yes, I was rather pleasantly surprise to find that the more updated dielectric system of these types of caps renders their latent dissipation factor suitably low for the rapid cycle pulse discharge duty of being employed as the main tank cap of a large RSG/pole pig driven Tesla coil. I was also quite surprised to locate this type of cap in a relatively low capacitance, thus rendering their C within a suitable range for Tesla coil usage in combo with an adequate ceiling voltage rating (13.8 kVAC). Locating more than one of these identical 0.25 uFd rated (single phase) units meant the possibility of seriesing just two to obtain 0.125 uFd @ a whopping 27.6 kVAC rating! Their GE model # is 9L18CCL101 (whatever that means) and the only drawback is the single bushing (w/casing ground). However, this minor caveat can easily be addressed by simply 'floating' their seriesed outer casings and using the two bushings as the inputs. Not that I really needed these, but considering the o
ft
en fickle nature of availability of affordable capacitors of this caliber, I like to keep a good supply of suitable replacements in case the 0.1 uFd @ 75 kVFD Maxwell pulse cap that I am currently using in my big coil lets out its 'magic smoke' ;-))
I have two of these ~33 lb. beasts on their way to me now. They are used with no guarantee, but having no visible 'bulging' of the outer casing and having been simply removed from decommissioned switch gear in a fully operational environment, I figure the odds are pretty high that these beauties are still quite functional and well within their nameplate specs. The real kicker is that I will have <$150 in both of them, including S&H :-) Gotta love that!
Happy sparking,
David
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On May 18, 2017, at 11:22 AM, Bert Hickman <bert@xxxxxxxxxxxxxxxxxxxxx> wrote:
Hi David,
Your plan sounds excellent. As Terry mentioned, you really don't want to tear into these caps. I've also been there, done that, while autopsying a failed/ruptured 175 pound GE pulse cap. NEVER again - what a MESS... :^/
Even worse, unlike castor oil or mineral oil, many of the low-flammability dielectric fluids that GE (and others) used were really nasty, foul-smelling solvents. When the cap failed, the leaking fluid literally "ate" the backing off the indoor-outdoor carpeting below.
Your two caps in series should work great just as they are, while increasing the bang size a bit. A little tweak on tuning and ballasting and they work great. And, they should be virtually bullet-proof.
Play safely and make big sparks,
Bert
David Rieben wrote:
Hi Bert, (and Terry O),
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