Re: high voltage resistors

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

Original poster: "Mark Broker by way of Terry Fritz <teslalist-at-qwest-dot-net>" <mbroker-at-thegeekgroup-dot-org>

Wow, more responses than I thought I'd get!

The resistors are for stage-seperation in a small Marx Generator, 
admittedly rather
OT for this list. . . .  So the duty cycle is about a 20kV pulse for a couple
microseconds followed by about one second of charging currents (less than 20mA
max based on the latest info on NST loading).

Failure of a resistor (or cap) would be a huge pain, since the whole thing 
will
eventually be submerged in transformer oil.  Due to its intended use, I would
actually prefer a high-L reisistor a la wirewound.  I was actually 
deliberately
overlooking wirewounds, since I was affraid of arcover inside the 
resistor.  :o  I'm
looking for a body lenght of 1 inch or less, as this will fit best in the 
design.  (The
caps are rated for 22kV in oil and have a 1.0" lead spacing, FWIW.)

Although not a terribly elegant solution, it looks like a few carbon comp 
in series
may be the best way to go afterall!

Thanks for all the responses!

Mark Broker
Chief Engineer, The Geek Group


1/21/2003 3:19:45 PM, "Tesla list" <tesla-at-pupman-dot-com> wrote:

 >Original poster: "Jim Lux by way of Terry Fritz <teslalist-at-qwest-dot-net>"
<jimlux-at-earthlink-dot-net>
 >
 >Sure enough, WW resistors aren't great for pulses (although, maybe the high
 >L isn't a problem in an application), but they do work just fine in lots of
 >other HV applications like bleeders, etc.  And, they are really cheap as
 >surplus. You just need to look at your application and decide if failure is
 >a problem or relatively benign.
 >
 >Mark didn't say whether he was actually trying to pulse through the resistor
 >and what the pulse characteristics are.  I would interpret this as a
 >requirement for low duty cycle, high peak power, but not necessarily a fast
 >pulse application. An example of such an application would be an energy dump
 >for a stored energy system.
 >