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From: nelson@bolyard.wpd.sgi.com (Nelson Bolyard)
Newsgroups: sci.electronics
Subject: wanted: device to turn brownouts into blackouts
Keywords: brownout blackout
Message-ID: <1991Apr15.180755.19771@odin.corp.sgi.com>
Date: 15 Apr 91 18:07:55 GMT
Sender: news@odin.corp.sgi.com (Net News)
Distribution: na
Organization: Silicon Graphics, Inc., Mountain View, CA
Lines: 57

This morning at 6:19 AM PDT, a power line went down in the city of
Milpitas, causing a brownout condition that lasted for 58 minutes
before the power went out completely.  During the brownout, we got 60
volts AC out of the wall sockets.  This did nasty things to my
computer equipment, and to the compressor motors in my fridge and
freezer, and to the furnace blower.  Motors just don't like low
voltage.  

We were alerted to the problem because the telephone answering machine
started speaking the time of day out loud continuously until my wife
got up and shut it off.  Then she noticed that none of the fluorescent
lights in the house worked, and that the computer (that we leave on
around the clock) seemed to be continuously rebooting.  The
refrigerator was trying very hard to start up, and I heard the little
self-resetting circuit breaker opening with its distinct pop and
closing a few minutes later.  It did this until I shut it off.  I also
shut off the freezer in the garage and the furnace.

When the power finally came on an hour after it went completely out,
it blinked a few times.  It didn't come on cleanly.  I suppose the
blinking was caused by tremendous surge currents as every motor in
Milpitas came on at once.  I sure was glad that I had shut off all my
computer equipment before the power came back on.

I don't want or need a UPS.  I wouldn't mind occasional clean power
failures.  None of my computer equipment reacts badly to complete power
failures.  My disks all park themselves, and my disk cache is
write-through, not write-back, so I don't have the **ix problem of
trashed file systems after power failures.  But brownouts and power
blinking can't be doing anything good to my computer equipment nor to
my motorized appliances.

So I'm looking for a device that I can hook into the power line for my
computer equipment that will cut all power off completely if the power
quality drops below some threshold (say 90% of normal), and will remain
shut off until the power has been restored to normal for at least a
minute or so (to guard against blinking and surges).

I already have all my computer equipment plugged into a power outlet
strip that supposedly pretects it from "surges and spikes".  I can
envision a unit that plugs into the wall outlet that contains a big
relay (or a little relay with big contacts) and a little circuit
board, and a single switched outlet into which I can plug my power
strip.

If you know of such a device ready-made, please let me know.
If you're interested in designing such a beast, I'd appreciate the
schematics so I can build one.  Who knows, maybe there's a business
opportunity here.

Thanks in advance for your replies.  Please post them, or email to the
address below.

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Nelson Bolyard      nelson@sgi.COM      {decwrl,sun}!sgi!whizzer!nelson
Disclaimer: Views expressed herein do not represent the views of my employer.
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