Re: Spark Gap Width

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

Original poster: "Daniel Barrett" <dbarrett1-at-austin.rr-dot-com> 

     Chris, let me throw in that you can approach this the opposite way also:
With the gap directly across the xfmr as Matt describes, start with the gap
open (no arc) and then adjust the gap closer until an arc is struck. Turn it
off, open the gap just a bit more and you're done.
     Matt, the issue I was worried about is that you can strike an arc and
pull it out much longer than the initial strike distance, giving a setting
that is much too wide...
db


----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Tuesday, May 25, 2004 6:02 PM
Subject: Re: Spark Gap Width


 > Original poster: Mddeming-at-aol-dot-com
 >
 > In a message dated 5/25/04 3:20:49 AM Eastern Daylight Time,
 > tesla-at-pupman-dot-com writes:
 > Original poster: "Chris Fanjoy" <zappyman-at-hotmail-dot-com>
 >
 >     Perhaps this is a rather basic question, but I'm hoping someone can
 > enlighten this newbie. I've looked around on the web and haven't been able
 > to get much help.
 >     My specific question is, how does one determine what width of spark
gap
 > is needed? Is there a specific guideline, such as so many mm per kilovolt?
 > This is for an air-cooled static gap BTW (actually several gaps in
series).
 >     Thanks for any advice.
 >
 > Hi Chris,
 >       For an AC powered coil, I have found a reasonable first
approximation
 > to be 0.5 mm/kV of rated (rms) transformer output. The precise mm/kV is
 > difficult to predict. It is dependent on temperature, humidity,
cleanliness
 > and geometry of electrodes, altitude, barometric pressure, smog level,
(and
 > often moon-phase, planet alignment, size of audience, etc.etc.)
 > This is the quick & dirty, math-free easy way:
 >      Place a simple gap across your transformer without the coil tank
 > circuit connected. Open the gap to where it will just not fire. Measure
 > this distance. This is your critical safety gap upper limit. Your main gap
 > can be set as wide as possible to give consistent operation without
 > exceeding this number. In the case of a multigap, the sum of all the
 > individual gaps must not exceed this limit.
 >      If you're into resonant rise or other run-to-destruction fetishes,
 > then all bets are off.. Just go for it and use a little less gap on your
 > next transformer ;^)
 >
 > Hope this helps,
 >
 > Matt D.
 >
 >