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Re: Lightning Surge Arrestors and MOVs



Original poster: "Terry Fritz" <twftesla-at-uswest-dot-net>

Hi David,

MOVs will not work on a pig transformer.  On an NST the power is very
limited and they can survive for a short while taking the full NST voltage
and current.  However, on a pole pig transformer, those little MOVs will
flame out like flies in a bug zapper!  Spark gaps and the arrestors you
mention can take the "big hits" a pole pig needs.

Cheers,

	Terry

At 11:29 AM 1/7/2001 -0500, you wrote:
>Hi all,
>I'm going to bug you guys with another little question that
>has been on my mind lately. As part of the safety gap sys-
>tem of my pole pig driven Tesla system, I have employed
>a 12 kV rated utility line lightning arrestor (the cigar shaped
>porcelan insulator with one "line hot" lead on top and one
>ground neutral lead on the bottom. I was wondering if this
>device worked like the MOVs that you can purchase from
>Digikey. I know from hi-pot testing of the arrestor that it safe-
>ly shunts serious overvoltages above its rating to ground with-
>out suffering any noticable damage to itself. It works pretty 
>well with my 14400 volt pig, but as the pig is slightly overdriven
>to up to 16800 volts from the 0-280 volts from the variac, it does
>start clipping the output of the pig when I turn up the variac past
>about 80 on its 0-100 scale dial. I was wondering if I could use
>a sufficient # of the 1800 volt rated MOVs from Digikey in series 
>for this same purpose or if I could just find I higher voltage rated
>utility line lightning arrestor for this. Also, where can I get some
>more of these lightning arrestors? I bought my current 12 kV 
>rated arrestor froman individual vender at the Richmond, VA Tes-
>lathon in ' 99 and I have no idea where he got it. I assume you 
>could probably obtain these arrestors from companies that sale 
>and rebuild pole pigs (T&R Electric,ect.). My local electrical utility
>uses 7.2 kV and 13.2 kV primary line voltages, so their 13.2 kV
>arrestors would probably still be a little low for my application. I
>was thinking  a 16 kV to 20 kV rating woulk be about my target 
>rating. 
>
>Thanks,
>David Rieben
>