[TCML] Pig safety gaps - was Winding the primary
Gary.Lau at hp.com
Wed Jul 9 08:24:17 MDT 2008
Correct - I no longer use a strike ring.
I'm curious how a streamer striking your secondary could have caused primary-side damage. I would guess that it must have also struck the primary, causing the arrestor to avalanche, and with the current of the charged cap (or maybe just the pig secondary) behind it, smoked the arrestor.
That's an interesting report that normal safety gaps don't extinguish with a pig driving it! I'm surprised that this hasn't come up before. Sounds like the standard practice of using drawer knob electrodes (?) doesn't cut it in your application! Have you tried a horn gap? Sorry, but I have no experience at that power level.
Regards, Gary Lau
> -----Original Message-----
> From: tesla-bounces at pupman.com [mailto:tesla-bounces at pupman.com] On
> Behalf Of David Rieben
> Sent: Wednesday, July 09, 2008 9:44 AM
> To: Tesla Coil Mailing List
> Subject: Re: [TCML] RE: Winding the primary
> Hi Gary,
> Nice and aesthetically pleasing coil. I assume that you're
> NOT using a strike ring with your newer 2-layer primary?
> IIRC, you were one the main proponents of the idea that
> a strike ring was not really necessary. The physics would
> seem to back up your thoughts on this issue but I think
> many coilers just don't like the idea of the output sparks
> power arcing directly to the primary coil. In my personal
> experience, I once fired my coil outdoors on a windy day
> and the wind blew one of the power arcs back into the
> lower end of the SECONDARY coil, in spite of a well
> placed and RF grounded strike ring. Good thing I had
> a decent safety gap (actually an 18 kV rated distribution
> arrester) in place across the output of my pole pig trans-
> former as the arrester failed as a dead short! At first I
> feared that my pig or my primary capacitor had bit the
> dust but isolation showed the arrester to be the culprit.
> Glad the arrester sacrificed itself over the transformer
> or the capacitor as it was much cheaper to replace.
> BTW, I use sufficinetly rated arresters in place of a
> physical safety gap because when running coils in the
> multi-kVA power range, I've always had trouble with
> resultant arc not extinguishing once the safety gap fired.
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