UPS (Uninterruptable Power Supplies)... kinda long.

[Dan Watts]

In article <9007220923.AA22348 at mcirps2.med.nyu.edu> root at MCIRPS2.MED.NYU.EDU writes:
>   ... stuff deleted ...
>I don't feel the need to use my iris in a power failure by candle light.
>+-----------------------------------------------------------------------------+
>| karron at nyu.edu                          Dan Karron                          |
>| . . . . . . . . . . . . . .             New York University Medical Center  |
>| 560 First Avenue           \ \    Pager <1> (212) 397 9330                  |
>| New York, New York 10016    \**\        <2> 10896   <3> <your-number-here>  |
>| (212) 340 5210               \**\__________________________________________ |
>+-----------------------------------------------------------------------------+

I too don't care to use my PI by candle light.  I can touch type, but it is
difficult in the dark.

Where I work here in Derry NH, the local electric companys power isn't all
that great.  It's not uncommon to have brownout conditions one a month or
more.  I've solved this in two ways.  One other computer I have is a Data
General MV/2000.  Since I don't really care if it shuts off during a power
outage, I've got it hooked into a Radio Shack surge supressor outlet that
will turn off if the voltage goes below a certain point.  Once off, it can't
come back on without manual intervention (push a button to reset).  This
solves a problem that caused my MV to fry it's memory once.  The power
browned out, then came back, then browned out. This cycle repeated a few
times and the end result was a dead memory board.  Now, my system just shuts
off at the first brown out and I wait till the power seems better.

For my PI, I took a different route.  This machine is my main development
system and as such, I don't want to rely on Unix's fsck to recover it.
For this system, I purchased a Para Systems 600 watt standby ups.  It has
an LED bar graph to show me the current usage (right now I'm using about
200 watts for the PI, QIC-24, QIC-150, 350MB, 600MB, 19" color monitor,
modem, fax/phone).  When power goes below an acceptable limit, the unit
generates an audible alarm (which can be silenced by pressing a button
on the front of the unit).  I then have a bar graph display showing me
the current battery life.  I tend to continue working, though I start to
terminate jobs that I can start back up later.  If the power doesn't return
soon, I perform an orderly shutdown and turn everything off.

As protection against when I'm not around, I've got another Radio Shack
power outlet in-line between the PI and the UPS.  If the UPS uses up all
the battery supply, it will shut itself off before the batteries are
damaged.  This then causes my RS outlet to turn off so at least I won't
have to worry about the PI having the power fluctuate any.  I will have
to deal with fsck when I reboot, but that's life.  I may eventually
get the external power fail indicator that Para Systems sells and try
to interface it to the PI.

Hope this helps.  The UPS cost us $930 with shipping ($899) and I got
a free load tester outlet too.  The load tester comes in handy to measure
current load of new equipment when I get it.

Dan
-- 
#####################################################################
# CompuServe: >INTERNET:uunet.UU.NET!ki!dwatts    Dan Watts         #
# UUCP      : ...!uunet!ki!dwatts                 Ki Research, Inc. #
############### New Dimensions In Network Connectivity ##############