As stated, it's rare but it has happened. When a major storm hits, power is out for _days_; a really major storm, for _weeks_.. I watched them restring power wires after a bad storm, it is not trivial work.
In such circumstances the telephone is needed more than ever.
The traditional Central Office had a diesel generator in addition to its batteries, so a few days is not a problem.
I think your memory is failing you. All the #1 ESS offices in Illinois that I visited/worked in ... which were a LOT, had battery power for about 4 hours and were routinely tested on batteries for an hour. Most had diesel generators that were manual start only.
That was pretty much state of the art when the original ESS machines went in. I suspect that the recent vintage digital offices rely more on generators and less on batteries but the total current drain is MUCH less and I've only seen a few of them ... and didn't pay much attention to the power plants.
Not really practical to start a diesel that quickly ... because it (usually) needs to warm up a bit for the speed to stabilize before you cut the load to it. Something like a backup system powered by natural gas may not have that limitation but when you have any battery backup at all, it isn't desirable to start the generator that quickly, to prevent false starts on momentary "hits".
That seems very doubtful. First, Morris, IL was not an "ESS1" but a laboratory experiment. Second, since electronic switching must have constant power or everything fails I would suspect the battery would be much longer lasting
There was a post divesture case in NYC where a central office was, by agreement, cut off from commercial power. But they forget to certain tasks. The switch ran about four hours until the batteries ran out but the staff was aware at a training class. Kind of a big scandal for AT&T since it was a planned shutdown.
I can recall touring an Illinois Bell ESS CO southwest of Chicago back in the 70s. Memory fades over time, but I recall the basement filled with the largest lead acid battery farm I'd ever seen. Wooden floors/shelves everywhere.
I don't recall the expected life of that battery backup capacity, but it seems to me it was on the order of days, not minutes.
If I recall correctly, too much testing could greatly shortened those expensive battery's lives. They were (are) designed to "float" rather than operating on a current-draining load.
I have see some computer room backup diesels that start up that fast, heated cooling system to keep the block at operating temperature, and hydraulic starters that will spin fast enough that there is power output even if the diesel doesn't start on the 1st rotation.
The Diesels at a nuke plant are kept heated and have "start & provide power" times in the low single-digit seconds; they are how you power an emergency shutdown...
Ahem. No battery is designed to float. They are designed to provide power ... and float when not doing that. I worked in those offices for 25 years and I assure you that their capacity to provide that power WAS tested regularly.
Except for a bomb or fire, there isn't really much that will damage a 2.1 volt CELL that stands 4 feet high and is about 16 inches square; they really aren't fragile, mechanically OR electrically!
The biggest battery backup I've ever seen was in the early 1980's while taking a tour of a AT&T satellite feed [antenna] farm in Kimbles, PA near Lake Wallenpaupak. The dishes were more than huge.
Again, I respectfully disagree. As I recall the history, "a few years before Morris went live" there wasn't much of anything, just designs on paper. I'd have to check the Bell Labs history. Once again, Morris was _not_ a production installation, but a special test site. They knew at the onset the hardware would not be used in production; it was more of testing the concept of stored program control.
Once again, in electronic terms, 1/3 of a second is a very long time, far too long for electronic circuits to wait for a power stoppage. Even back then electronic clock [cycles] were [measured] in thousandths of a second.
Further, diesel technology back then was still crude enough that "1/3 second fast start" was quite advanced and not dependable enough for a mission critical function like a C.O. They simply couldn't take the chance that the generator engine might have to "crank" a few times before kicking in.
But, unlike an unattended central office, hopefully the operators will have brought the diesel generators on-line at a nuclear power plant while [implementing] a check-list that gets them running before they are actually required to be brought on-line.
If, on the other hand, the starting of diesel generators at a nuclear power plant [has to be on] that [kind of] "hair trigger" then perhaps the opponents of nuclear power generating stations are correct, and our next TMI could happen any time.
[moderator snip]
***** Moderator's Note *****
This thread is getting hotter than a loose bus bar in busy hour: let's tone it down an octave or two. I _DON'T_ want to have a debate about nuclear power!
And, _PLEASE_, pay more attention to spelling and grammar! I know it's Spring, and I know it's hard to review your posts when you're (pun intended) charged up, but have mercy on the moderator, OK?
Bill Horne Temporary Moderator
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Been there, done that, 1400 amp hour cell and a 6 inch Crescent wrench, lucky for me, the wrench was dropped onto the posts, not slipped while in use. Anyone need a spare movable jaw & 3/4s of a hanging ring?
-Hudson
***** Moderator's Note *****
OK, it's time for the annual retelling of the story of my Central Office Technician Rating examination!
New England Telephone had a rating system for technicians: after about five years of experience, techs could take an examination given by two supervisors, to obtain "Rated" status. As a rated tech, you got first pick of vacations, preference in tour assignments, and ~$50 additional
- 1980 money, mind you - in you paycheck every week. Trust me: it wasn't for show, and you had to have a sponsor - another rated tech - recommend you for the test and accompany you to the exam.
Part of the exam is on power room operations, usually a fairly short section for all but Power techs: since I was in Toll, I only had to study some basic fire safety and general rules.
Unfortunately, after an hour explaning duplex circuit operation and the proper procedure to compensate for ground resistance in EMX-1 and EMX-2 equipment (yes, I'm that old), my mind went totally blank, just when one of the examiners asked me "Bill, what can you tell me about tools used in the power room"?
I sat there, feeling like I could hear (pun intended) a pin drop, with my mind's gears grinding. Instinct kicked in: I reached into my head's gearbox and hit the BS Overdrive switch.
"Ah, OK, well, it would have to be a tool manufactured and approved for use in an explosive atmosphere, under current inspection, and properly maintained".
My sponsor kicked me under the table. I looked right at him. The supervisors were holding their hands in front of their mouths, trying not to laugh. Time stood still for a great many very long seconds.
... and my mental transmission finally caught, and I said "of course, you need to make sure the handle is properly insulated", at which point the supervisor guffawed, and asked me "How do you do that, Bill"? I answered, "Well, ah, you can put tape on it".
They shook my hand, still laughing, and I was a made man.
Bill Horne Temporary Moderator
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Cripes, folks. The 1/3 second was the 'reaction time' for the genny to _begin_ the start-up sequence. They were *NOT* producing stable power after 1/3 second.
If the power was out for -less- than 20 cycles, the generators did not [even] *try* to start.
Telco "backup" power configuration varied widely depending on the situation at the particular C.O. -- how likely it was to have a 'more than momentary' failure, duration of a 'typical' failure, etc. Also taken into consideration was how long it would take to get a 'spare' generator there, if required.
"Manned" C.O.s did tend to have primarily "operator-started" generators -- i.e. somebody had to 'push the button' before it turned over. ('policy' was to engage the generators ASAP after utility power was confirmed 'down'.)
Hoever, "unmanned" offices did rely on "auto-start on power-fail" generators. They did have several hours of battery run-time -- *but* the generators kicked in 'immediately', so that the battery power could be saved for 'last resort' use -- e.g. if the generator _failed_, the C.O. could stay operational "for a while", while waiting for "people" to arrive.
By definition, emergency shutdowns are unplanned, unscheduled, events. There are tight standards on the backup power for that reason. I vaguely recall triple-redundancy; i.e. 3 large Diesels, where one of the three can do the shutdown.
In telco ops; by history and design, everything runs from -48V. I've seen KS-number fluorescent lamps, etc. I suspect there was a 48V soldering iron somewhere. I believe the goal was the battery plant could keep essential services up (without the generator working) long enough for a truck-mounted unit to arrive.
In the early 1990's, I know of a CO feeding a large local ISP. Ma had to run fiber in from a more distant CO to provide the expansion channel banks needed -- She had run out of -48V capacity in the nearby one.
There was a great deal of back & forth testimony in the Maryland PSC case about FIOS & other changes. One topic was how Ma pawns off the power issue to the homeowner, and won't maintain the Battery Backup Unit. All the CO generators in the world won't help you when you have no local power.
Biggest one I ever saw was PaeTech's Providence, RI switch. They had a
6' high rack that had to be about 30 feet long and maybe 4' or 5' deep of batteries for the 5ESS/2000 switch.
***** Moderator's Note *****
Real battery rooms cover the entire floor of the building, as did the batteries for the panel exchange in use at Back Bay in Boston until
1972. They were Exide black monoliths, about 18 inches on a side, and they could provide a busy-hour load in excess of 500 amps.
Every time I saw them, I half-expected to find an ape with a bone in his hand and "Also Sprach Zarathustra" playing.
Bill Horne Temporary Moderator
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Diesel is definitely not the way to go. I remember when we were doing disaster scenarios the first thing to go would be transport of diesel fuel.
Natural gas however would remain on for a slightly longer duration. That's why we went with a natural gas fired 125kW generator for our server and IT space.
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