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From: mrb@psueclb.BITNET
Newsgroups: comp.misc
Subject: Surge Protection on Power Lines
Message-ID: <882@PSUECLB>
Date: Sat, 28-Nov-87 09:02:23 EST
Article-I.D.: PSUECLB.882
Posted: Sat Nov 28 09:02:23 1987
Date-Received: Mon, 30-Nov-87 07:20:40 EST
Organization: Engineering Computer Lab, Pennsylvania State University
Lines: 32

Hi --

With all the recent postings about surge protection on power lines, it is
important to restate/emphasize one thing ---

Make sure you fuse (or otherwise overload protect) any circuits leading to
surge protective devices.....or, in other words, don't just hang 'em across
the power lines without a fuse in the way.

Now sure, the fuse can blow and you'll be left without that surge absorber
in service...that's why some people put indicators (neon lamps, etc.) across
the surge protector so you can tell when they are in circuit.  Won't tell
you if the movistor is "worn out" --- just if it is across active lines.
When the fuse blows, the lamp goes out.  Of course, you have to look at the
indicator every once in a while, but that's another story.

One particular episode convinced me of this...back in the mid-1970s, I worked
at a TV/FM station.  We were always losing rectifier stacks, etc. with every
big thunderstorm that came our way.  So the boss bought these mammoth
thyristor-type surge protectors in a big steel box, and hooked them (as
intended by the mfr.) across the incoming 480 V - 3 phase AC.  No fuses, etc.
in the way.  Well, comes the first big thunderstorm and BLAMMMMMO!  One of the
devices couldn't hack a surge (maybe a direct hit, who knows?) but in any
event it failed and became a dead short.  Blew the steel cover right off the
box!!  Complete with smoke and sparks and all.  Impressive!

So fuse those surge suppressors, even the little ones on distribution
circuits.  It's cheap protection.

MRB @ PSUECL