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Re: Looking for an 18KV distribution arrester
Original poster: FIFTYGUY@xxxxxxx
In a message dated 5/1/07 12:36:51 A.M. Eastern Daylight Time,
>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.
I didn't notice it until the end - it was the last thing I saw after I
had tested it, dissected it, and inspected it. It was a little unnerving,
since I wasn't wearing eye or ear protection in my crowded garage.
> 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.
IIRC it was a Winchester/Olin .22 blank (big "X" headstamp).
> 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 also checked with a 15/30 NST, hi-volt probe on DMM, and noted the same.
>I've heard of explosive charges being used in fuses,
>but not in arresters.
I've seen some supplemental coordinating distribution fuses blow (500A
at 32kV rating), but I think they blew in half due to internal
You have to have done something pretty stupid to blow one of those up,
> 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
It's a blank, but even the lowly .22 LR has a nominal chamber pressure of
24,000 psi. I've heard that the ones for powder-actuated tools have
pressure ratings. A "little" .22 is capable of a lot!
>The larger 21kV units are all MOV+gap types, I'm pretty certain.
I *did* notice some sparks shooting out of my larger arrestor when I was
running a mis-tuned 6" coil with my pig last week. So an internal
gap would make
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