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Re: [TCML] Strike rings - to use or not to use; was: Newbie Grounding Question
Hi Adam,
I'm not sure as to the previous use that my arrester saw since
it was an "ebay special" picked up from some female ebay
seller in Canada whose main merchadise was yard sale finds.
I got it for next to nothing (I think the $1.99 opening bid +
S&H) and the S&H was about 80 to 90% of my total cost for
it IIRC. I do know that it was the new generation butyl rubber
exterior type instead of the older style glazed porcelain exterior,
though. I ended up just purchasing a 36 KV rated arrester to re-
place it so it will take twice as much voltage to fry it this time. I
think with a 110 kV biL rating, my 14,400 volt pig should still be
relatively safe ;^) As far as using an open ball gap for the safety
gap, I've always had trouble with the arc not wanting to "shut off"
at these power levels once it did fire. That's the reason that I
prefer distribution arresters to open ball gaps for this prupose.
David Rieben
----- Original Message -----
From: "Yurtle Turtle" <yurtle_t@xxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Saturday, December 29, 2007 1:05 PM
Subject: Re: [TCML] Strike rings - to use or not to use;was: Newbie
Grounding Question
Just theorizing here...
Your lightning arrestor is purely voltage driven,
without regard to energy. However, a big coil like
yours could have a theoretical instantaneous output
power in the hundreds of kW. While it may not be
enough to hurt your transformer or cap, the
instantaneous event (or series of events) may have had
enough energy to fry your arrestor. It probably did
what it was supposed to, once it saw >18 kV. Once the
arrestor clamped to ground, all those hundreds of kW's
saw a very low impedance path to ground.
My arrestor consists of a series air gap, followed by
MOV's. As I understand it, MOVs can only take a
certain number of overvoltage events before they
finally fail short. My arrestor was very old, and may
have already seen some real world lightning events
before I got it. Was yours used as well? Mine's seen a
number of primary strikes without failing. However,
I'm currently only running at around 6-7 kVA.
Adam
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