[TCML] Bleeder for a Pulse Cap - how to?
jimlux at earthlink.net
Mon Jul 26 07:10:09 MDT 2010
Joe Mastroianni wrote:
> Hi All,
> Another question, if I may.
> So far I've been using MMCs built in strings of 18 made of the illustrious 942C CDE caps. Each one is fitted with it's personal 10M bleeder resistor.
> I've been recently toying with the idea of picking up a pulse cap or two from eBay, but then I wondered what would be the safe way to "escape" the cap. I'm used to a 30-sec approach time when I stop the coil and have to go fiddle. With a pulse cap, I'd probably get myself zapped.
> What do you guys use for bleeders on those things?
On my HV gear using pulse caps, I have a HV relay that shorts the cap
when power is not applied. There's a big 300W resistor in series to
limit the discharge current (and excitement when the relay closes.
OTOH, we're talking about 30 uF at 20-30kV here, which is probably more
energy than you'll have in a tesla coil.
Also, before actually touching anything, I use a pair of grounding hooks
with series 1k resistors to limit the current to about 20A. Attach
hooks to cap terminals, wrap wire across terminals, done.
On a MMC, it's nice to have resistors because shorting the ends of a
string of capacitors does not guarantee that the capacitors in the
string are discharged (imagine two caps charged to 1kV and -1kV in series).
You could just string a bunch of 10 Meg resistors in series and use it
as a bleeder.
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