Re: Lightning Arrestors (was Geek Pig)

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

Original poster: "Christopher Boden by way of Terry Fritz <twftesla-at-uswest-dot-net>" <chrisboden-at-hotmail-dot-com>

Interspersed.....


>Original poster: "Bert Hickman by way of Terry Fritz <twftesla-at-uswest-dot-net>" 
><bert.hickman-at-aquila-dot-net>
>
>Chris,
>
>Turns out they ARE a bit more complicated than that - remember that
>arrestors are designed to provide a safe path to ground for HV
>transients, but should open back up once the surge has gone. They must
>be able to rapidly recover and hold off normal line voltage. Ideally,
>they should pull little or no current at normal line voltage.

Thus a spark gap would be the perfect, cheap, simple solution. That's why it 
made sense.

>
>To meet these requirements, most arresters are actually a combination of
>spark gaps and MOV's, with the MOV element actually made of silicon
>carbide. I happen to have a clear glass 9 kV (Pyrex) arrestor that I use
>for demos - it has a MOV that's about  9" long by 3" in diameter, in
>series with eight spark gaps (each about 1/16"). Will be interesting to
>see what you find inside yours... :^)
>
>-- Bert --



It's killing me........I'm half temped to accidently "drop" it to open it up 
:) I have a pair of the little ones, so I can open one, but they're REALLY 
proud of their sealing mechanisms. The big ones have what looks to have once 
been a liquid (like tar), and poured in around the base. The insulator 
actually sets inside a 4" deep aluminum base, and is held in with this black 
nastiness. It works like glass, very brittle, powdery when it shatters, has 
a grainy, flaky property (like creosote, flint, or mica) and smells terrible 
when filed. What IS it? and how do I get rid of it? I want to open this 
without destroying the insulator....and cutting the case does not look like 
fun as I don't know what's on the other side.

I hate a puzzle in progress. :)

Thank's for the info, I could use any MOV inside, but it still doesn't make 
any sense to me why they would go to the trouble (and expense) of building 
anything more than a simple spark gap in a sealed container (these don't 
appear to be vented in any way).

Can the gaps be used as a static gap? What are they made of?

Constantly learning......constantly changing opinion :)

Christopher A. Boden Geek#1
President / C.E.O. / Alpha Geek
The Geek Group
www.thegeekgroup-dot-org
Because the Geek shall inherit the Earth!





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