Re: [TCML] Spark gaps (again)

["David Rieben" <drieben@xxxxxxxxxxx>]

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 
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>
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