Battery power support today [telecom]

semi-offtopic

Battery technology was previously discussed in this newsgroup.

The NYT reported that the Phila transit system will use battery packs to pick up power generated by braking subway trains and return it when trains acceleration. (Electric motors can be easily switched to become generators).

Also, some power could be fed back into the general power grid and help control frequency deviations from the desired 60.000 Hz.

see:

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Historically, telephone switching offices as well as PBXs had large battery supplies which were kept charged on a 'float current' from power supplied by rectifying commercial power. If commercial power failed, the batteries would be charged by large diesel engines and generators. All of this power plant was a major installation as part of the central office.

It has been suggested that some central offices, remote switching nodes, and cell phone antenna sites, no longer have generators to supply power in a commercial outage after the batteries run down. This is troubling. Plenty of relatively normal nasty snowfalls can bring down commercial lines requiring more an eight hours to restore. A tough weather event would generate greatly increased telephone and datacomm usage, further taxing the power supply.

Hopefully the new battery technology referred to in the article could perhaps allow telephone plant to _economically_ have greater standby capacity, especially when there isn't a diesel engine available.

(Anyone know how many kilowatts of power are consumed by a telephone central office at the busy hour?)

Reply to
Lisa or Jeff
Loading thread data ...

On Mon, 13 Jun 2011 14:25:19 -0700, Lisa or Jeff wrote: .........

But what level of weather (or other major) event do people *expect* comms to keep functioning?

With the increasing quantity of major natural disasters affecting population centres all around the world, I'd like to see some data on what ends up being the more reliable and available voice comms infrastructure - either old POTS or Wireless?

Does anyone know if there have been studies done to show what actually happens in disaster areas, rather than what we all individually may

*think* happens because one day our own lives may depend on the reality rather than the perception?
Reply to
David Clayton
[Moderator snip]

Very few cell towers are equipeed with generators these days. Gensets tend to be maintenance intensive & prone to failure when called on to run for more than a few hours. The current practice is to have, depending on the location & how critical the site is to the transmission network, between 8 & 24 hours battery backup. During major power outages, operators will move portable generators between sites, charging the batteries up then moving on to the next site. This is labour intensive but cheaper & more reliable in the long run.

As for how much current a CO uses that's very much dependant on the size of the office. I've seen medium sized offices drawing 1500-2000 amps [at] 48 volts, I wouldn't even want to guess what a large site would use.

H.

Reply to
Howard Eisenhauer

It varies with the number of line appearances. At a given number of line appearances (urban size office) SxS consumes a hughe amount of power, then 5XBAR much less, and 5ESS/DMS-100 far less tthan 5XBAR.

I saw the power meter in the main Pasadena, CA CO when all but one office code was SxS (the one code was 5XBAR for toll common control). This was early 1970s. I don't remember the power being consumed but it was humgeous (at about 2:00 PM).

Reply to
Sam Spade

[Moderator snip]

In much of the US the most common type of widespread weather emergency is an ice storm. Since these storms cause both trees and power utility poles to collapse into the street, that poses obvious problems to mobile crews attempting to restore service or to keep sites operational by recharging batteries with mobile generators. The other weather caused threats to service availability include flooding, wildfire (bush fire to Australians) and Hurricanes / Typhoons. I deliberately left out tornadoes because tornadoes are not wide area events and adjacent area infrastructure can usually provide service except in the actually struck area. I also left out blizzards and other major snow events because in the absence of ice they generally effect transportation a lot more than communications and power.

Earthquakes can hardly be called weather but they do cause widespread damage to communications infrastructure. If you think about how earthquakes and wide-area weather events damage communications infrastructure, you will probably come to the conclusion that all types of communications infrastructure will be damaged by these types of events. The wires and fibers on which all of these systems depend are turned into plates of cut up spaghetti laying on or buried in the ground by such events. A cell site can be completely intact but without connections to other towers and the computers that operate the system that makes no difference.

What may be driving public concern is the greater dependance that people have on these systems and the fact that modern communications has become more brittle with it's increasing sophistication. In 2003 my land line POTS telephone was the only utility that remained working after Hurricane Isabel came through my area. It stayed working because it was a wire line and it was powered from the exchange. I had always made it a point to have one wired telephone connected on the busiest floor of my home. Now I have FIOS or Fibre Optic Service for the sake of the much faster data rate it gives me. Since fiber cannot carry power my phone will die as soon as the battery in my Customer Service Unit (CSU) is exhausted. The CSU has a button to engage the remaining battery power in order to make an emergency call after the CSU has shut itself down to avoid damaging the battery but I only learned about it by studying the unit. Most Customers will not even know of that button's existence. I also have a generator that I maintain and test quite regularly but not many homes are so well equipped.

One real barrier to public understanding of these systems is that the folks in charge of them use security concerns to shield their actions from public scrutiny. I volunteer in Fire and Rescue, and some years ago my county was rendered radio dark by a shrew chewing through a fiber optic cable. Since the details of the system are considered a security matter I was threatened with disciplinary action for even inquiring about the resilience measures of a system that I depend on for my very life while crawling down long snotty hallways at 0-dark-30 in the blessed AM searching for other peoples relatives. When the Volunteer Firefighters Association threatened political action the Department of Information Technology pulled in their horns and claimed it was all a misunderstanding.

-- Tom Horne

Reply to
Tom Horne

Per Tom Horne:

After reading about the aftermath of Katrina (and knowing nothing much technical...) I started thinking it would be a good thing if there could be some sort of standard for cell towers and internet connection hardware where, in a pinch, every box could be operated from 12v DC. Seems like automobile batteries would be in pretty good supply in almost any disaster...

Reply to
Pete Cresswell

Since the thoughtful discussion by Tom Horne at , contains the following sentence

1) I'll toss in the following idea which my wife actually suggested some years ago, and which I think is remarkably ingenious.

Suppose your gasoline-powered lawn mower included access to its drive shaft in some way _from the top_, and the mower manufacturer also sold a small free-standing (unpowered) generator with a matching fitting _on the bottom_.

When the power fails, pull off a small cap on the top of the mower housing, opening up access to the motor shaft a small distance down inside a 1" or so diameter hole.

Drop the generator onto the top of the mower, firmly held in place with some matching brackets or fittings on top of the mover enclosure, and with its shaft making a mating connection to the mower shaft. Pull the starting cord, and you've got electricity -- and in many parts of the country your new primary power source will have been not just tested but usefully employed once a week, most of the weeks in the past year.

[I've in fact been making use of a smaller but analogous single power source, multiple accessory tool combination earlier this morning, in the form of one of a remarkably useful hand-held Braun electric gadget which a shaft which matches up to and powers a whole variety of kitchen blenders and stirrers. And Honda in fact actually both gas-powered mowers and gas-powered home generators, does it not?] 2) As another take on the same residential emergency power backup theme: I have 10 kW of solar on my roof (large 4-household residence, all on one meter, hence most of our usage would otherwise be at premium rates that are much are than the baseline rate in our area). But, this system goes out and becomes useless for generating 110 VAC if the local utility power fails (and I understand why).

But suppose the inverters for this system included some very modest additional electronics that could also divert a small fraction of the juice from these panels to directly charge, _DC to DC_, a small array of a half dozen or dozen of the standard 18 V or 24 V batteries that power ordinary hardware-store variety power tools (drills, small saws, etc), all sitting in a rack right beside the inverters.

Our local power company is knocked out for a week, but there's still some sunshine? ­­ we could at least glean some renewable energy every day to power small tools, maybe communications gear, lights for after dark, maybe even some cooking.

And all the rest of the time, we could still keep these batteries charged without the DC-to-AC-back to DC efficiency that's otherwise involved in doing this.

I think I'll go talk to my patent attorney . . .

Reply to
AES

In any disaster and the immediate aftermath, I would assume that people would be trying to use the remaining comms infrastructure far more than normal, so would any (probably) degraded infrastructure be able to handle the demand?

There may not be much point in keeping one or two cell towers up if thousands of people - including emergency workers - hammer them with demand that cannot be fulfilled. Same goes with any Internet infrastructure, if some survives it may be totally saturated (and virtually useless) because we expect it to be there 24/7 these days.

Reply to
David Clayton

In very general terms, my impression from the news media and informal conversation is that old landline POTS is more reliable than Wireless or Cable phones. How 'much more' I can't say. In some plain old regular snowstorms that snarl traffic my cellphone wouldn't work on account of busy circuits, but I always got dial tone on landlines.

That is a good question. As we know from the literature, the old Bell System went to great lengths to assess and minimize that risk against economic realities.

But to answer such a question we must first define what a "disaster" is. My town was flooded by the river three times in four years after not having a problem in 50 years (and fortunately none in a few years since). Each flood was deemed a "disaster". But our flooding wasn't as bad as the midwest very recently, and of course no where near as bad as Katrina and New Orleans. (Our C.O. is on a main street above the flood plain.)

Likewise, last winter we had a nasty 20" snowstorm that brought down power lines. Landline phones kept working. Restoration of electric power took between six hours and 60 hours, depending on where the crews got to first. That was a 'borderline disaster' and they were ready to open schools as emergency shelters. But it is not at all unusual in the US for a large area to get hit with a very severe snow or thunderstorm causing power outages of 96 hours. Then we have the really bad, but fortunately rare tornados.

(I suppose they have some official rating scale, but I don't know it.)

Reply to
Lisa or Jeff

[Moderator snip]

Try the Bedini generator website.... Richard Powderhill------------------------------

Reply to
Richard Powderhill

You may be able to get a patent, but the reality is that all of these schemes have very serious safety issues. Your solar array is connected to the grid and backfeeding the grid poses serious safety issues to the linemen (linefolks???) trying to restore your service. The same logic applies to the lawn mower generator as it will likely be plugged into the house electrical system, with the same backfeed issues. BTW, lots of folks say they'll flip the main breaker, but that's not a guarantee that they will in a blackout. The disconnect form the grid needs to be automatic and complete. That is a fundamental safety requirement.

The proper way to do standby generators is to connect them through a listed transfer switch to prevent any backfeed issues. Also, your inverter on the solar array needs a 60 Hz source to sync to, so without utility power it needs to shut down. The power it generates is dependent on the sunlight reaching the array, therefore it varies from minute to minute (clouds anyone??). Connecting to an almost infintie bus (the power grid) allows proper operation. Standalone operation requires matching the load to the generated power, second by econd. Not a trivial or cheap task.

All appliances expect 60 Hz power with reasonable voltage regulation. Great care needs to be had to make sure that is not violated to avoid safety issues. Do things "right" and live long and prosperous... ET

Reply to
Eric Tappert

If you run a lawnmower engine constantly for a day or so, it will fail. The bearings on them are very cheaply made, they are not intended for continuous operation.

I have used improvised PTOs on lawnmowers to drive VW bug alternators for emergency power. It works, but it's not a long-term thing, and by long term I mean a couple days.

--scott

Reply to
Scott Dorsey

But dial tone doesn't mean you can call anywhere. During the Northeast blackout in the 60s I was in Rhode Island and when the lights went out it seemed like everyone was trying to call their relatives. We had dial tone 90% of the time (other 10% dead air) but no calls were going through. We got the famous "Please try your call later." recording. After a couple of hours we were able to call Maine which was mostly unaffected by the blackout.

Mark Smith

Reply to
Mark Smith

[Moderator snip]

Although admittedly off topic for this group I thought I would add...

Amateur Radio Operators (Hams) have made so called pup generators for many years. They take a lawnmower engine; or any small engine for that matter; and install a metal plate on to it through which the drive shaft protrudes. They then install a truck alternator through the same plate and with a drive belt and the correct pulleys you have a very large supply of DC current to keep batteries charged. Hams have used pups to power radios and other station equipment that runs on twelve volts DC but with the addition of an appropriately sized inverter you can also run AC loads. The use of somewhat larger batteries allows you to use an inverter that is quite a bit larger than the alternator alone could supply. That is because the inverter needs to be sized so as to be able to start loads rather than just to run them. A refrigerator, as one example, is much greedier in it's use of electricity during starting than it is when running. So the batteries supply the peak starting load to the alternator and get recharged by the pup which is sized only to carry the charging and running loads. The plates are available ready made by mail order from . My only relationship to them is in using their instructions.

There are additional possibilities. A few high end ride on lawnmowers are available with power take offs. There are generator heads available that are designed to run from power take off shafts. That combination produces a lot more power than the pup inverter combination which maxes out at about 3000 watts. High end riding mowers can power generator heads with capacities to 10,000 watts. Full sized tractors can power much larger generator heads. There are also 120 Volt alternators in the 10,000 watt range that can be fitted into the engine compartment of pick up trucks and full sized vans.

-- Tom Horne

Reply to
Tom Horne

In the US, and possibly elsewhere, there is a system in place to provide emergency workers with priority access to the cellular network during emergencies. In the US the cell phone to be used must be programmed into the system in advance. When the emergency feature is engaged that call goes to the head of the cue.

I devised a somewhat more devious approach which I used on localized large incidents. I would pass the word to the incident commander to be ready to make his call. I would then plug a carbon arc light bulb into the inverter on one of the apparatus at the scene. That creates a radio dead zone several hundred feet across. The commander was told to hit send as soon as the light went out. It worked pretty well. What we were dealing with was that the news people would get a circuit and hold it open in order to insure an out of band talk path to their producer, editor, or whoever. That would saturate the available capacity of the nearest cell towers. The interference caused by the arc would blow the news people off line freeing enough capacity to allow the incident commander to make his call.

-- Tom Horne

Reply to
Tom Horne

After an Arkansas ice storm some years back; Bell South deployed portable generators at SLC's and such; and soon discovered that if/when the power was down for multiple days, there was no chain&lock big enough to keep them from being stolen.

One thing that DOES work well [outside of shake&bake states located on fault lines..] are in-place natural-gas driven generators at the SLC. Even in the worst weather, natural gas is VERY dependable outside of earthquake regions. But they are not free; either to install or maintain.

True, but lots of outside plant will survive; not ALL earthquakes crack the earth wide open, and even downed poles often have intact trunkage. Power, however...

We are far less self-reliant than we were a few decades ago.

{FIOS vs POTS} This is a valid issue. It's not helped by the fact that Verizontal tries to whitewash concerns with "no one will ever be dialtone-less" bell juice when we know the truth; no power, no talk.

The best answer is discard the 7.2 AH battery and buy a 60-75AH battery at WalMart; and a few lengths of wire. THAT will outlast a multi-day outage. [It will take a week to recharge, but so what?]

Gads yes.... Always kill the messenger....

BTW, vertical shaft lawn mower engines are ill-suited to driving belts; they lack bearing designed for side loads.

Reply to
David Lesher

My question is based on the rapid changes in comms technology and the way we increasingly rely on 24/7 availability these days, you would think that this is the sort of thing that needs some solid quantification (is that a word?) of what works and what doesn't so we know if we building more or less resilient infrastructure.

I would have thought that this would be the sort of thing industry/governments would be finding out as a matter of urgency, or Universities would be pursuing as a matter of public importance (versus researching slight increases in cancer risks using cellphones, for instance).

If I was 20 years younger I might initiate a study myself! ;-)

Reply to
David Clayton

I suspect some areas of the old BOCs have maintained their backup standards, while others have not. As to grade of service, I suspect most old BOCs have more options now to control the network and trunk availability because of all the vast amount fiber they now have. I also suspect much of this is a closely quarded secret.

I have a Vonage line and two cell phones. I also have an AT$T wireline line, which I am not about to get rid of for any number of reasons, E911 being one of them. My AT&T wireline is toll restricted based on the premise, why pay for that when the Vonage line is toll free to much of the world.

Reply to
Sam Spade
+--------------- | In 2003 my land line POTS telephone was the only utility that remained | working after Hurricane Isabel came through my area. It stayed working | because it was a wire line and it was powered from the exchange. I | had always made it a point to have one wired telephone connected on | the busiest floor of my home. Now I have FIOS or Fibre Optic Service | for the sake of the much faster data rate it gives me. Since fiber | cannot carry power my phone will die as soon as the battery in my | Customer Service Unit (CSU) is exhausted. +---------------

The good news is that you can power the CSU from a small local UPS if you like. The bad news is that it may not help very much if there's a remote DSLAM between you and the CO, since *its* batteries have a limited hold-up time as well (~8 hrs, I've been told) if city utility power goes off wherever the DSLAM is.

[A friend of mine had this happen to him during one of the Colorado fires not to long ago. *He* had plenty of UPS, solar, and even backup generators, but the fire fighters told the local power company to shut off distribution to that whole area and the Qwest remote DSLAM feeding him died a short while later. (*sigh*)]

-Rob

+--------------------------------------------------------------+ Rob Warnock 627 26th Avenue San Mateo, CA 94403
Reply to
Rob Warnock

This sounds like a scaled-down version of what the a store down the road here sells: generators that can be hooked on the 3-point hitch of a farm tractor, and generate 15 or 20kW AC. The nicer ones also have a 300A welder output, all for about 1/2 the price of an equivalent diesel generator.

Problem with scaling it down to lawnmower size is that the governor on a lawnmower isn't as quick and reliable as the one on 'real' generator, so keeping the output at a reasonably constant voltage at 50 or 60Hz under varying load might be a bit of a challenge. Switching power supplies don't have much of a problem with that though, so for comms gear it could work well.

If such a contraption existed, I'm sure I could sell a bunch of them here (.za), but I wouldn't consider selling this to the US - way too much potential for getting sued by some idiot who lost the cover, got some piece of clothing caught in the shaft while mowing the lawn, and lost an arm (or worse)

-j

Reply to
jack

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