RE: Counterpoise and MMC demise

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

Original poster: "Malcolm Watts by way of Terry Fritz <teslalist-at-qwest-dot-net>" <m.j.watts-at-massey.ac.nz>

On 19 Jun 2003, at 8:08, Tesla list wrote:

 > Original poster: "Peter Lawrence by way of Terry Fritz 
<teslalist-at-qwest-dot-net>" <Peter.Lawrence-at-Sun.COM>
 >
 > Chris,
 >        your 6kV-30mA NST has a Res Cap value of 13.26-nF, and your cap is
 > (22 / 6) * 4 = 14.67-nF which is too close for a static gap - the Res
 > Cap value is the value at which the NST-Cap combination can resonate up
 > to absurdly high voltages.  Static gaps are notorious, if the gap for
 > whatever reason fail to fire once the voltage on the cap doubles, if it
 > fails to fire for twice in a row the voltage on the cap triples.

??  If the gap is set to fire at some voltage it will fire at that
voltage. The cap can't ring up beyond that voltage.

Malcolm

  You
 > were probably just "lucky" that your cap did not fail while running with
 > the earth ground, switching to a counterpoise probably had nothing to do
 > with it.  My first recommendation is to use about 1.5 * the NST Res Cap
 > value for your primary cap when using a static gap, add at least one and
 > maybe two strings to your cap.  My second recommendation is to use
 > caps that have already been tested in TC service, I'm using the panasonic
 > ones that I got though Terry and have never had one fail.  Lastly, I'm
 > I'm using longer strings and only putting 750VAC per cap, even though
 > Terry and others report long life using the DC rating in TC-AC service.
 >
 > good luck,
 > -Pete.
 >
 > (ps, the Res formula for 60-Hz NSTs is nF = 2.652 * mA / kV).
 >
 >
 >