Re: Looking for an 18KV distribution arrester

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "J. Aaron Holmes" <jaholmes@xxxxxxxxxxxxxxxxxx>

Fascinating.  Yes, the 3kV ones are by Kearney, but I
too broke one open (literally--with a sledgehammer)
and I didn't see such a thing.  All I saw was a
silicon carbide disc about 1.5" long and 1.5" in
diameter with spring-loaded contacts to hold it in
place.  Could have missed something in the rubble,
though! ;-)  Unfortunately, this was years ago and I
didn't take any pictures.  I played with one using a
15/30 NST and variac and found that I could hear a
faint buzzing when the thing went into conduction.
Seemed to work great.

I've heard of explosive charges being used in fuses,
but not in arresters.  That is interesting.  I may
have to break another one open now! :-))  Of course,
if there's rim-fire ammunition in there, a
sledgehammer may not be the best tool to use this
time!!! :-O

The larger 21kV units are all MOV+gap types, I'm
pretty certain.  I've got a couple of units made by
Ohio Brass (Type GP Series 3 "Dynagap"--can't find any
literature on them, unfortunately), and a couple by
McGraw Edison units (buried under a bunch of junk now,
or I'd cite the model#).  I did at one point find
literature for the McGraw Edison ones, and it had a
nice cutaway diagram of the innards, which employed no
explosives IIRC.  I've lately acquired a 24kV PT, but
haven't tested these larger arresters yet.  I need to
do that!  Should be fun :-)

Regards,
Aaron, N7OE

--- Tesla list <tesla@xxxxxxxxxx> wrote:

> Original poster: FIFTYGUY@xxxxxxx
>
> In a message dated 4/28/07 7:56:22 P.M. Eastern
> Daylight Time,
> tesla@xxxxxxxxxx writes:
>
>  >I've also got a dozen or so 3kV
>  >ceramics the size of soda cans.  These latter ones
> are
>  >brand new in boxes with mounting hardware.
>
>      Those wouldn't happen to be the "Kearney"
> arrestors, would they?
> A local surplus buddy of mine gave me one to check
> out. 3kV, new in
> the box with hardware. He has a bunch.
>      I've posted this before, but I'll say it again:
>
>      I dissected one of those 3kV Kearneys, after I
> tested it with a
> NST. Did its job with the NST across it. However,
> when I dissected
> it, I found a .22 LR blank was designed into it. I
> presume when the
> current level gets high enough, the blank is
> supposed to blow the
> endcap off the thing and quench the arc.
>
>      So be careful how you mount those.
>
> -Phil LaBudde
>
>
>
>
> ----------
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>
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>