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Re: Tolerances and Study on Rotary Spark Gap spacing . . .



Original poster: "Terry Blake by way of Terry Fritz <teslalist-at-qwest-dot-net>" <tb3-at-att-dot-net>

Hi Captain,

The spacing is more an issue at low voltages.  If you have a close spacing
(like a total gap space of 1/8" or less), you can play with tuning the
primary or adjusting the sync of a synchronous rotary.  You notice I did say
total gap spacing. If you have a propeller rotor like my stuff, then there
are 2 gaps, which would share the 1/8" total for say 1/16" per gap.  But if
you have more gaps in series (4, 6, 8, etc) then they will all add to the
total gap spacing.

If I recall, it is 25 KV to 1 inch.  Even though that is subject to all
kinds of conditions, I'll plug in that number.  Lets say that you have a
14.4 KV PT.  At full capacitor charge, it will break a gap at 14.4 / 25 =
5/8".  This is the largest total gap you could have and still get the rotary
fire consistently.

For a 2 series gap rotary spark gap;
At low power, the spark fires when the gaps are closest together, say 1/16".
But at high power, the spark fires when the total gap is about 5/8", or
about 3/8" at each gap.  This happens well in advance of the gaps actually
lining up.

Here are some photos to show what is going on.

http://www.tb3-dot-com/tesla/sparkgaps/sparks/index.html

If you set the total gap spacing to say 1/2", then nothing would happen
until you got the power up pretty high, and then it go on at near full
power.  Not as nice as the slow crank up.  IMHO.

Terry Blake
Coiling in Chicago
http://www.tb3-dot-com


----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Tuesday, January 21, 2003 3:21 PM
Subject: Tolerances and Study on Rotary Spark Gap spacing . . .


 > Original poster: "Mccauley, Daniel H by way of Terry Fritz
<teslalist-at-qwest-dot-net>" <daniel.h.mccauley-at-lmco-dot-com>
 >
 >
 >
 > Has anyone done a study on the tolerancing of electrode spacing in rotary
 > spark gaps in the closed circuit position.
 > Basically, I'm trying to determine a operational tolerance on the gap
 > electrode spacing and what
 > the performance vs. electrode spacing function would look like it.
 >
 > Or more simply put, how much difference would it make of say 50 mils
 > electrode spacing vs. say 200 mils electrode
 > spacing be during actual operation.  Or doesn't it matter that much as
long
 > as the arc can jump the gap?
 > I'd try the actual experiment myself, however, my four inch coil is
 > disassembled at the moment and my time is very
 > limited.
 >
 > Thanks for your help.
 >
 > Captain Corona
 >
 >