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Re: [TCML] Spark gaps (again)



Hi all,

It seems from the discussion that an optimum SG design is kind of a
"balancing act" between maximum quenching and minimum losses.
With my large Green Monster Tesla system, I originally used a single
point asynch rotary gap and found that when the power has really
cranked up, I began to have quenching problems. So I upgraded the RSG to a pair of SG points, set 180 degrees apart on the ro-
tor (a total of 4 gaps now, instead of 2). This greatly improved the
quenching but intoduced excessive heating of the flying electrodes
(eight 3/8" x 2" long tungsten rods) because they are now each
taking on 2 bangs per revolution instead of one. The heating was
so severe that I was getting blistering of the G-10 disc material
around the flying electrodes! I addressed this problem by chang-
ing my ballasting as well as adding adjustable collars to each end of each of the flying electrodes, butted up to the surface of the ro- tary disc. The collars are made of aluminum and add to thermal mass as well as thermal conduction. These measures seems to have pretty well corrected this problem. BTW, I cannot tell any
difference in the output of my coil with 4 gaps as opposed to 2
gaps but then again, I am running some pretty high power levels.

http://www.flickr.com/photos/33464569@N05/
http://www.youtube.com/watch?v=GGb-qWIqx7g&feature=related

David Rieben



----- Original Message ----- From: "jimlux" <jimlux@xxxxxxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Wednesday, March 04, 2009 10:13 PM
Subject: Re: [TCML] Spark gaps (again)


otmaskin5@xxxxxxx wrote:
I've been following earlier discussions about higher losses
associated with multi-segmented?spark gaps (i.e., Richard Quick type)
compared to a?single gap.? It's clear that the experience of this
group has been power losses are significantly less with?a single gap
style with adequate airflow.? But I'm not sure I caught why that is.?
What is the reason that a 0.27" single gap loses less power than an
9-gap / 10 pipe RQ gap that has total gap size of 0.27"?? If total
gap spacing is the same for both, why would one be more lossy than
the other?

The voltage drop across a gap is the sum of a fixed cathode drop (on the order of 50-100V) plus a "arc column" loss which is quite small (for high current arcs).

So multiple gaps in series has about the same arc column loss, but multiple cathode drops.

Good quenching though.



One other question, has anyone experimented with a RQ style using
only 2 parallel pipes for a single gap???If so, what were the
results.? With good air flow, it seems this set up?would be good for
keeping the gap cool considering airflow goes between, around and
through the pipes.? And you could make the pipes longer, say 4 to
5?inches for better heat sinking ability.?


I use 3 sections of pipe arranged in a triangle. Two are fixed, and the one in the middle is adjustable.

Sorry to take everyone back to an old topic, but I've been away for a
while.? Thanks, Dennis Hopkinton MA _______________________________________________ Tesla mailing list Tesla@xxxxxxxxxxxxxx http://www.pupman.com/mailman/listinfo/tesla


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