RE: spark gap spacing

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

Original poster: "Pete Komen by way of Terry Fritz <twftesla-at-qwest-dot-net>" <pkomen-at-zianet-dot-com>

Hello Jeremiah,

It would help to know more about your setup.  What is the HV transformer?
Is the 11.5 KV AC or peak?  Are the 10 caps in one string all that you have?
That would be 6.8nF at 12.5 KV.  If the 11.5 KV is AC then the peak voltage
is 1.414 * 11.5 KV = 16.26 KV or well over the limit for your caps.  I don't
know the breakdown voltage of air but for my 12/60 NST, the spark gap is set
about 1/4 to 1/3 of an inch.  With sharp edges I can get more than 1/2 inch,
but a 1 inch gap is much too large.  I would worry about resonant voltage
build up with a gap so large.

I set the gap as follows:  with the NST connected to the protection circuit,
connect the spark gap to the output (after the protection circuit).  Set the
gap so that it always arcs across but if opened farther, it doesn't arc.
Leave it there.

Regards,

Pete Komen

-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Saturday, June 09, 2001 10:29 AM
To: tesla-at-pupman-dot-com
Subject: spark gap spacing

Original poster: "Jeremiah by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<jmeizis-at-kc.rr-dot-com>

Hi,
I was wanting to know how far you should set your gap?  Today i was doing
some
testing and i set my gap real close together and it was a very poor
performance.  I noticed the more i opened up the gap the better the
performance.  When i opened it up all the way, and i was turning up the
variac
it finally started arcing at 11.5 KV then one of the capacitors on my MMC
blew
up.  It didn't actually explode but part of the insulation popped off, it
was
kind of weird.  Why did that happen in the first place?  The caps i'm using
are
10 .068uF 1.25 KV and the gap is an inch wide at full open.
Thanks
Jeremiah