RE: Shorted turn?

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

Original poster: "Mark Broker by way of Terry Fritz <twftesla-at-qwest-dot-net>" <mbroker-at-thegeekgroup-dot-org>

Steve,

I believe you are talking about the strike ring, typically located several
inches above with a diameter several inches larger than the OD of the
primary.  A gap  is left in this 
ring.  If the ring is intact, then it would act as a shorted turn.  Since
the strike ring is relatively close to the primary, the coupling would be
very high.  This would essentially 
shunt the primary energy directly to ground.  I initially left the ring
intact, but added a gap after reading a post on this list....  It saved me
hours of frustration and cursing.....

As for your "vision of 'potential' problems...." (hehe, I love a good punny
;-)   I had BAD arcover problems between the outer turn of my primary and
the strike ring during a 
demo (second public demo).  I was able to get icky little purple sparks,
but not the nice fat, blue 120Hz streamers I'd become accustomed to.  As I
recall, it was hot and 
VERY humid (probably 85F, 90+%).  There were 3 or so "extra turns" on the
primary (total of about 11), and the strike ring was about 2 inches away
from the primary (so in 
theory, the max voltage differential was about 15kv*1.4*11/8 = 29kV).....
After the failed demo, I removed about half a turn, increasing the gap
approximately .5".  I've never 
had taht problem again, though I HAVE had turn-to-turn arcing (no sharp
points, 3/8" tubing spaced 3/8"), which I never was able to figure out (esp
after running the Geek 
Group's coil with no problems with 1/4" tubing spaced 1/4" with no topload,
giving a tune point of about 2.5 of 15 turns!)  But never had any problems

Mark B.
G-5 #10
The Geek Group's Chief engineer


(My first post from my new apartment (yes, I FINALLY found a real job!))



10-15-2001 6:45:04 PM, "Tesla list" <tesla-at-pupman-dot-com> wrote:

>Original poster: "Steve Greenfield by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <alienrelics-at-yahoo-dot-com>

<snip>

>Now: What are people doing to avoid circulating
>currents in the guard ring? I mean that ring I
>sometimes see just above the primary, grounded to
>protect the primary windings from strikes. I don't
>mean the secondary smaller toroid I often see on
>larger coils just below the main toroid at the top of
>the secondary.
>
>If you can get arcs across a gap in a toroid where the
>current is at it's lowest, I can see potentials for
>problems in a guard ring located right above the
>primary.
>
>Steve Greenfield


<snip>