-----------------------------------------------------------------------------------------------

Picture this;
(It *really* did happen)

It's 'way-back-when' &, around 0200, the system operator has his feet up on his desk in the operators' office (a glassed-in room located in the middle of a very large room housing a really big mainframe), waiting for a routine periodic diagnostic run to complete. All of a sudden the power starts going off & on & off & on, continuing in rapid succession (we don't need no stinkin' backup power around here!). Luckily, & quite by accident, the main circuit breaker box for the entire room is fairly close. The startled operator leaps to his feet, toppling the roller chair he was reclining in & almost falling on his ass in the process. Lunges toward the door of his office, yanks the door open, runs into door (combo of door swinging inward & moving too fast), recovers nicely (still on his feet!), & manages to get to & throw the main breaker before any damage is done!

--------------------------------------------
On Mon, 3/27/17, via tml list <xxxxxx@simplelists.com> wrote:

 Subject: Re: [TML] starting your ship
 To: xxxxxx@simplelists.com
 Date: Monday, March 27, 2017, 11:47 AM

 On 26 Mar 2017 at 10:53,
 Greg Nokes wrote:

 > >
 On Mar 25, 2017, at 11:54 AM, (via tml list)
 > > More stories from the Great Blackout.

 > >
 > >
 > > So being required to have backup
 power or the ability to cold start
 > >
 just means that gear is installed. Doesn't mean that
 it'll actually
 > > *work* when the
 real thing comes along. Not even if it has been
 > > tested.
 > >
 > > Usually it's a *real* mess trying
 to *realistically* test emergency
 > >
 power. You can make sure the generator runs, but unless you
 actually
 > > cut the main power
 completely, and without warning, you can't *know*
 > > that everything will work.
 > >
 >
 > I used to work in an environment where the
 power systems were rather
 > important -
 we were "allowed" 5 min of planned downtime a
 year.
 >
 > We had
 batteries in each equipment rack with 1 hr run time each.
 A
 > room based battery for the datacenter
 with 2 hours runtime. A hydrogen
 > fuel
 cell which could run the facility for 2 months. A diesel
 > generator with 2 weeks fuel. And
 connections to two separate power
 >
 grids.
 >
 > We tested
 it monthly.
 >
 >
 First we would cut utility power, and wait for the generator
 to cut in
 > - that took a few minutes and
 tested the batteries. Then we would shut
 > down the generator and the fuel cell would
 take over.
 >
 > It
 was fun to watch the first few times - but then it became
 pretty
 > routine. :)

 One real world situation that your tests
 didn't cover and has killed
 more than
 one backup setup is having the utility power go away and
 come back several times in quick succession.

 This tends to fuck things up
 because the flucuating load does
 interesting things to the switching gear for
 the batteries, and the
 generator startup
 sequence won't like it much either.

 This, BTW is why some older surge suppressor
 power strips require a
 *manual* reset after
 a power failure. It protects the computer from
 damage from the rapid up/down/up sequence.

 I've had problems with
 power "flickers. My "best system would shut
 off at flickers that other system (including
 several digital clock)
 kept running
 thru.

 I've still to
 replace the big UPs that vanished when they remodeled
 my apartment a few years back, but I was able
 to replace the battery
 in an older, smaller
 one for only $25 and tthat's enough to keep it
 going thru a "blip". Even if it
 probably wouldn't give me as much as
 30
 seconds of run time if the power stayed off. As I can afford
 it,
 I'll be replacing the batteries in
 other old UPSes and evenhtually
 getting
 another big one.

 Oddly
 enough, the current cable modem has built-in battery backup.

 Which isn't much help since the router
 and switches aren't hooked to
 UPses
 yet.

 --
 Leonard Erickson (aka shadow)
 shadow at shadowgard dot com

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