Battery power support today [telecom]

Objection! Assumes facts not in evidence.

There are inverter control arrangements readily available that will open the connection to the grid and divert the solar output to batteries on the loss of synchronization with the grid. These are not in common use but they do exist. As for the connection of generators to household wiring it is readily and inexpensively done. Listed transfer interlocks are available for sixty dollars or so from most electrical panel manufacturers. They are manual in operation but so long as the physical interlock is not tampered with in some radical way it is not possible to cross connect the utility and the localized power source. Thus I would quarrel with the statement that "The disconnect from the grid needs to be automatic and complete." It does not need to be either automatic or complete to be completely safe. In fact most transfer arrangements are not complete because between having a switch, or additional switch pole, to open the neutral conductor and isolating the neutral from ground at the generator the later is always cheaper although it is not always done.

Let me take a moment to say that the real risk of relying on the main breaker alone comes from two problems. The one you have addressed is human error. The other is the common existence of sneak current paths in many home wiring to grid connections. Examples of such paths include; power theft by a previous owner of the property, peek period metering arrangements for certain loads that were discontinued by simply paralleling the service conductors to a single meter; and the most common one, which is the existence of hundreds of thousands of split buss panels where the main disconnecting means is up to six breakers, switches, or pull outs rather than just one. When the back fed outlet is supplied from one of those six main breakers its utility supply pathway is always connected to the grid. Thus in order to get power into the home you have to close the disconnect that supplies the back fed outlet and the one that serves the lower portion of the panel that contains all of the single pole circuits. Doing that causes a grid back feed every time.

As for matching the load to the power source "second by second", that is where an inverter generator, or equivalent assembly such as a pup, battery, and inverter arrangement really shines. The inverter can adjust to the load much faster than any mechanical device and the Motor Generator (MG) does not have to adjust at all. The MG just keeps running at the same rate and leaves the battery to power the start up swings in the load. The MG need only be capable of carrying all of the running loads and can adjust to those loads at any rate that it can handle.

-- Tom Horne

Automotive Starting Lighting and Ignition (SLI) batteries that are used that way are rapidly destroyed. They are unlikely to survive more than a few deep discharge cycles before becoming useless. They are built with thinner plates than deep cycle batteries in order to permit them to provide a lot of current for the starting motor in a very short time. That is why they are rated in Cold Cranking Amps.

-- Tom Horne

[Moderator snip] [Moderator snip]

[Moderator snip]

It should be noted that perhaps my choice of "automatic" was misleading in the sense that a properly designed transfer switch can be manually operated. The specific technical requirements are in the listing specifications and, I believe (I don't have my code book with me...) that the NEC requires listed inverter and/or transfer equipment. In my area the utility also requires listed inverters for solar or wind power connections. That is the basic safety standard. Most inverters used with small wind or solar units shut the unit down on loss of utility power. Some inverters are capable of "island" operation, but are more expensive and not nearly as common. Special care must be taken when re-connecting to the grid as the frequency and phase of the inverter output will have shifted.

Transfer switches generally are required to "break" the utility connection before "making" the alternate supply connection. There are some types that do allow for a small interval of common connection, but again these are specially designed for specific situations and are tested to assure safety.

The neutral is grounded at the service entrance and the utility transformer (among other places...), so it can be treated differently than the phase conductors. Commonly it is not disconnected. There are circumstances where it is desirable to disconnect the neutral, but as was pointed out the transfer switch to accomplish this requires an extra pole. Timing of the neutral transfer with respect to the phase transfers may also be an issue.

The point of the original post was that gerry rigged connections that do not use the appropriate, listed equipment connected correctly are, in fact, very dangerous and should not be used in any circumstances.

ET

But presumably could handle "drop on top" accessories, if that capability were desirable enough to have been designed in from the beginning . . .

***** Moderator's Note *****

I think this is one of those "solution looking for a problem" situations. The subset of people who are willing to pay a premium to obtain a lawnmower with a PTO _AND_ the needed extra only-works-with-the-lawnmower alternator is, IMHO, too small for any company to make money at it.

Not to mention the frightening accident statistics associated with PTO's on tractors...

Bill Horne Moderator

I just want to note that when I talked to Verizon about FIOS, they were crystal clear on two aspects: 1) a big ugly box is attached to your house, and some people find those boxes objectionable, and 2) they depend on a battery in case of commercial power failure and in an extended power failure the battery will run out.

I forgot to ask if the battery runs down regardless if one is using the phone, or only when the phone is in use.

***** Moderator's Note *****

The battery will discharge at a lower rate when you're not using the phone, but as to how much time you'll save by staying on-hook, that depends on how much power the electronics draw compared to how much it takes to power the phone.

If you have a carbon microphone in your phone, the difference could be appreciable, but most phones use less power-hungry components now.

Bill Horne Moderator

I agree with [your statement about the] need [for] more quantification of this issue.

But I want to note that the phone co long considered 24/7 availability to be critical.

In a report describing a 1930s cutover from manual to dial, a carefully worked out schedule was prepared to minimize downtime and keep lines and trunks available for emergency calls. I was amazed at the checklist and detail. The switchboard was not disconnected until the last possible moment. If an emergency call happened to come through the cutover was held until the emergency call was completed.

Unfortunately, no one seems to be interested and the issue is taken for granted.

Actually, I think the public has been "dumbed down" in expectations over the last few lines. People seem to accept without complaint cellphone cutoffs, poor quality connections, or no service. Doctors are hard to get a hold of; they seem to dump urgent situations onto

911, even though one may be clearly ill, but not ill to require an ambulance.

(Some health insurers provide a nurse consultation 24/7, I think that's a good idea.)

As another data point on the preceding sentence:

Labs quite well. Not all were in telephony directly, more like electron device research; but several of them were old timers or senior figures with long careers at Bell who had been heavily involved in telephony throughout their careers.

Riding up a Squaw Valley chairlift with one of these old timers in the late 1980s, motivated by recent multi-day electrical power failures at my California house, and my inability to get any published standards for residential service reliability out of PG&E, I asked him what if any published standards for residential telephone reliability had existed in the now departed Bell System.

Answer: "No residential customer was to be without dial tone for more than 18 minutes total per year, for any reason under the control of the local phone company". [This is from now distant memory, but it was pretty close to this exact wording.]

Also, any call to an Operator or to Bell services like Repair was to be answered within 4 rings; and other similar explicit performance standards.

Wow! Were things like this actually monitored and recorded by the local telco? Was the resulting information made use of in any way?

Answer: "You bet! They had programs that monitored actual performance against these standards; these numbers went into performance reviews for managers; and they definitely impacted the promotions for managers at all levels, including upper levels."

Some years later I was visited by a former student who was at the time developing the hardware for some new form of telephone service to be delivered by a cable TV company over their residential TV cables. Thinking of my earlier exchange I asked him more or less the same question. The answer was that they were developing their hardware to a reliability standard of not more than 45 minutes/year downtime for any reason [I think that was the number; it was definitely under an hour/year.]

Finally, I recall that every once in a while I'd hear one of the black dial phones in one of my early houses give a single little "ping", often in the stillness of the night. Somewhere I acquired the impression that this was the telco, checking that we did indeed have dial tone. Other old timers may be able to say if this is correct.

Per Lisa or Jeff:

"Big" and "Ugly" might be subject to judgment of reasonable people.

But on our house's FIOS install, the outdoor box isn't much different from the box that handled the POTS interface.

Indoors, however, there is a box that is not there for POTS. I wouldn't call it big or ugly... but YYMV.

The trick with that box is to make sure they install it somewhere that it is convenient/easy to get to for battery replacement - yet out of sight.

I didn't think of this when they installed our first box and it wound up in the crawl space. Bad Idea....

I since got them to move it to the closet where I keep my NAS box and router. No problem there.....

Probably because while the central offices were fully backed up, the T carriers probably had no redundant power at the repeater points. That resulted in trunk losage, no doubt.

[call blocked during NE Blackout]

I've never seen T-carrier run off anything but loop voltage, aka span power. That's why there's 130 vdc to bite you when you are on the pair...

And since that span power is appled by/at the CO..

:[call blocked during NE Blackout]

:>Probably because while the central offices were fully backed up, the T :>carriers probably had no redundant power at the repeater points. That :>resulted in trunk losage, no doubt.

:I've never seen T-carrier run off anything but loop voltage, aka :span power. That's why there's 130 vdc to bite you when you are :on the pair...

48Vdc, I'm pretty sure. In any event, in the 60s there were still lots of L and N (analog FDM) trunks around. Since one of the driving reasons behind the T-carrier system was saving Ma money on her electric bills, it wouldn't surprise me to learn the L and N stuff got turned off, at least partly, when the power went off.

That is my recollection as well.

The exception was a pair-gain provision such as the Bell Systems SLC 96, which was used in rural areas and in areas of rapid residential construction. I believe the terminating SLC 96 box had to have local power. Anyone know differently?

I imagine SLC 96s are long gone for residential suburban areas but they likely still exist in some rural areas.

Oh yes, SLC's need power.

I was just in Aptos/Watsonville CA region, and there are SLC-96's on every other corner. The giveway is the line of shiny T1 repeater cans feeding same.

I'd be far happier if they were SLC-FO's as then I could get Hi-Cap from them.

But that's not to say the SLC powers the T1 feeding it. I assume that if the T span was long enough, it would be powered from both ends. [I don't know how many repeaters you could run on span power but it had to be a lot...]

[Moderator snip]

It all boils down to exposure levels and time. You simply need to put the antennas where the regions of ultra high RF fields are not readily accessible by people, and/or in places where they wouldn't naturally spend much time.

There's a *reason* they fence off exclusion areas immediately under an omnidirectional broadcast tower, and it's only partly to keep people from trying to climb the tower - which would probably end badly anyway, as the would-be climber gets electrocuted to ground trying to climb over the huge ceramic base insulator. Also why the power coupling transformer for the navigation beacon looks like two interlinked hula hoops, so the RF voltage doesn't jump the 12" gap. They don't want you hanging out under the antenna in that zone of ultra high RF - which decreases logarithmically with distance, so the people working 2,000' away or living 3,000' away are fine.

As to levels of microwave radiation around cellular tower sites, or the "Turnstile" antennas for Broadcast TV and FM radio - those are not omnidirectional antennas. The Sectional Panel antennas they hide in sets of three up in tall building elevator penthouses and church steeples and fake palm trees are rather directional and the vast majority of the energy is going out almost horizontally, there are no near-field issues in the building below them or ground level outside. Standing on the roof, inches in front of the antenna with the transmitters energized, is when it turns into a bad idea - which is why they lock the roof door.

But rational discussion is not in the mind of the "Fear Uncertainty and Doubt" (FUD) Crowd, there's money to be made in selling you their book or the latest snake oil scam as protection. Or in the case of medical FUDsters like the "childhood vaccinations cause (Autism, etc.)..." crowd, they don't have the answers but they want to scare you away from beneficial vaccinations anyway. These people are about to unleash nasty things like Polio on the world again, because they have achieved a critical mass of unprotected children. I have a feeling the problem is in the thimerosal (mercury) preservative and they have been phasing it out, but we need to let science determine it for sure.

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Both of those areas are a mix of suburban and remote rural areas. I can understand the SLC 96 on a road back in the hills of Aptos where the there are long distances with no houses, then a cluster of house. But, if pair gain is being used in the suburban part of Aptos I would think AT&T would be getting heat from the CPUC.

Sam Spade wrote: :David Lesher wrote: :> Sam Spade writes: :> :> :>>The exception was a pair-gain provision such as the Bell Systems SLC 96, :>>which was used in rural areas and in areas of rapid residential :>>construction. I believe the terminating SLC 96 box had to have local :>>power. Anyone know differently? :> :> :> Oh yes, SLC's need power. :> :> :>>I imagine SLC 96s are long gone for residential suburban areas :>>but they likely still exist in some rural areas. :> :> :> I was just in Aptos/Watsonville CA region, and there are :> SLC-96's on every other corner. The giveway is the line of :> shiny T1 repeater cans feeding same.

:Both of those areas are a mix of suburban and remote rural areas. I can :understand the SLC 96 on a road back in the hills of Aptos where the :there are long distances with no houses, then a cluster of house. But, :if pair gain is being used in the suburban part of Aptos I would think :AT&T would be getting heat from the CPUC.

Why? Modern nodes support all the services that are expected, like DSL, television, etc. They're fed with high speed backhaul (often fiber in dense areas).

Interestingly the only places I've ever seen pair-gain used is in the suburbs of RI. Never seen it used in the cities.

The CPUC regulates phone service. They have no control over DSL & beyond. It's up to PacBell [1] how they get get dialtone to

28 Barbary Line or similar. And since the DS1 fed SLC's are sunk cost; why would they change them out?

As for "pair gain" in suburban parts; what's your definition of same? I saw several in areas that may not compete with the Upper East Side or tract-LA, but are not Death Vally -- take 'downtown' Corralitos, for one. And in urban areas, it's VERY commonly used; a typical hi-rise will have a LightSpan or other SONET-fed terminal in the basement.

And thanks to Andrew for reminding me; I was pretty sure T's were powered with the +/- 130 series stunt, but could not find a good cite. Suffice to say it's enough so you *know* you got across something you shouldn't have... I seem to recall they could have 10-15 miles reaches easily; but the spec for signal [jitter etc, not power] went out to 150 miles.

1] or whatever their legal name is this week.

One word: concentration. It's been a long time, but my recollection is that the concentration ratio is 6:1. So, no more than 16 subscribers out of the 96 that are likely connected in a suburban area will get dial tone at any given time. For suburban areas SLC 96s were only suppose to be used until the LEC could provide dedicated subscriber loop.

***** Moderator's Note *****

IIRC, SLC-96's in "Mode 2", at least the way N.E.T. used them, were able to provide 100% dialtone (within the limits of the associated CO, of course), because they used "half rate" sampling to allow 48 channels per T-1 span. SLC-96 units had special common boards, and if they were inserted into "Mode 3" SLC-96 carriers by mistake, a 1000 Hz test tone would be received at 2000 Hz.

I don't think N.E.T. ever concentrated subscriber lines going through SLC-96 in a way that would deny dial tone at any time, but that may have been only in Massachusetts: in the 1960's, the company had installed electromechanical concentrators to maximize cable usage in low-profit areas, but the DPU made N.E.T. remove them because of political backlash.

Bill Horne Moderator