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The Fiber Age Meets The Power Grid
tulare writes: "According to this story at Wired, a research team is developing a way to replace the steel core inside high-capacity electrical power transmission lines with a fiberoptic core, which apparantly could provide a dual benefit: a 200% increase in emergency transmission capacity along with the ability to "carry several gigabits of data per second." (Per line?) There are a few kinks to work out - like how to splice the data in and out of the lines, but the story talks about an initial rollout date in 2003. Not soon enough to bail Californians out of the current crunch, but considering the benefits (less line sag, greater capacity without building new towers/routes), the effort certainly seems worthwhile." There's some more info from the researchers at this site as well.
I work for Corning Cable Systems, and we've been making this kind of cable for awhile. It's called "optical ground wire," or OPGW for short. The Europeans have installed lots; there's less here in the US. Though this particular deployment in California may not go up until 2003, you can go out and buy OPGW right now. Other questions answered: Yes, you can push many gigabits per second (Gb/s) down a single fiber. Telcos commonly run 16 Gb/s, 40 Gb/s, or more. Optical fiber is made of glass and therefore doesn't conduct electricity. The outside diameter of a standard fiber is 125 microns, which is about as thick as a hair and definitely thinner than common steel wires. A fiber does indeed have greater tensile strength than a steel wire of the same size.
The fiber cabling does not carry the power, they support the aluminium cabling which carries the power (previously, steel would support the aluminium lines)
The British tried to run TCP/IP over their power grid. Only problem: The street lights were broadcasting the signal.
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
This "new" technology is about 20 years old. Various utilities have been doing it for a long time, mostly using the static wire (the thin wire at the top of the tower that is used primarily for lightning protection). There are problem other than the obvious ones already mentioned, the big one being that when the static wire (or conductor in this case) is hit by lightning, the thermal shock tends to shatter the fiber (unless the conductive element is just melted, in which case the fiber breaks since it isn't strong enough to carry the two ends of the conductor).
For this reason, utilities have preferred to use their ROW to bury the fiber, rather than string it up on the towers.
If the researchers are claiming that an electric utility can achieve 25% better efficiency by exchanging more data, I have bad news there: utilites have been very heavy users of data processing at every level of the operation since the 1920's. The utility I used to work at had many joint projects with IBM in the 1950's and 60's, in fact, due to their heavy volume of transaction processing. A lot of new stuff (like check scanners) in the computing world was driven by utility requirements.
This doesn't even scratch the surface of the utilities' power flow management efforts. So I really doubt there is much in the way of SCADA that hasn't been thought of by now.
sPh
For more than 8 years, Hydro-Québec has been laying new electric cable whose core is fiber optic bundles.
Since they already go to the "last mile", they're bound to make a killing once the market is opened...
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This is why on big transmission lines, each phase is carried on two or four wires separated by spacers.
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The current power crisis in California is an aritficial construct. It is true that in a few years it would have been a reality, but this time it was orchestrated by the owners of the power companies. They did this by taking power plants off line without any technical reason, and simultaneously, to force an artificial shortage. (Check the court documents.)
Perhaps we should be grateful to those coniving (fill in perjorative plural noun). This may get us acting in time to do something to prevent the real problem from occuring. But this time it's an artifical problem, and I'm about as grateful toward them as I am toward the oil cartel for those artificial shortages a decade or two ago.
Caution: Now approaching the (technological) singularity.
I think we've pushed this "anyone can grow up to be president" thing too far.
This problem was caused because a prior governor took a public utility and "deregulated" it without any safeguards. This was a power system that was in a monopoly position in the state. Now the power system acquired a few debts in return for being deregulated, so it divided in half, took to cash into the parent organization, and left all the debts in a subsidiary. They it decided not to pay those debts. And since all the profitable assets had been given to the parent, the subsidiary had no way to earn the money.
It was financial manipulation. I'm sorry that the press hasn't been very forthcoming about this, but that's what happened.
Caution: Now approaching the (technological) singularity.
I think we've pushed this "anyone can grow up to be president" thing too far.
I like it. The Echelon guys would be in for a nasty shock when they try to splice that fiber...
OTOH, the next thing you know, California's internet fees go up to $1900 a month, compared with $30 for the average user.
Kevin Fox
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Kevin Fox
The NY Times had a pretty good article about this recently too.
It's not quite the same thing, but there are some interesting tensile-strength comparisons - including a type of glass fiber - here.
Slashdot - News for Herds. Stuff that Splatters.
Sometimes, but it's certainly not spelled "alluminum" and "steal" was just laughable.
Slashdot - News for Herds. Stuff that Splatters.
You mean "spelled", right? Sorry, couldn't resist.
Slashdot - News for Herds. Stuff that Splatters.
Spelling: aluminum, steel. Yeah, I know, you probably think spelling doesn't matter, but misspelling the core terms in what you're talking about makes you look like an idiot.
As the article you obviously didn't read thoroughly enough points out, aluminum is not stronger than steel in the way that matters. Pound for pound, aluminum has a 4-5% higher tensile strength than steel. However, the pound of aluminum will have a much greater volume, which means a wider cable, which means greater stresses from wind etc. and from ice in colder climates. Aluminum is also notoriously brittle, and has a smaller difference between yield vs. ultimate tensile strength. In other words, it will break where steel will stretch, and again the difference becomes even more important at lower temperatures. In conclusion, then, while aluminum does have advantages over steel for some applications, it is inferior to steel as a load-carrier for power lines.
It would actually be interesting to see the same sorts of comparisons between steel and the proposed glass fiber. Some kinds of glass have amazing tensile strength, but it's not clear whether those kinds are compatible with data transmission and glass in general is even more notoriously brittle than aluminum. It's likely to be far more complicated than "X is stronger than Y".
Slashdot - News for Herds. Stuff that Splatters.
Californians also want it out of their sight, and they want it to be totally enviroment friendly - aka, no cutting down trees or blocking a mountain lion's cave to put up a transmission tower. And if they could demand such a thing, they would want each new power line to be blessed with good karma.
I think the power crisis is the reality check they need, before something truly dangerous happens out there. It's a good thing that they get motivated to act by minor inconveniences like rolling blackouts. (Although I do have to say that no blackout has affected my life, but they all have served to annoy the crap out of me, so I can't diss CA too much on that one)
OK, first off, I want to make it clear that I am talkin' out my ass...
/. - I first thought - sending power down fiber optic cable (ie, using a multi megawatt laser pumping the fiber), and modulating the beam with data packets.
I didn't read the article - but from the comments, I understand that there isn't fiber optics in the cable, and that it is fiber reinforcment, blah blah - and maybe fiber alongside in some installations.
However...
Upon seeing the blurb on
At the home end - you would need some kind of light to electric converter (like a solar cell, only able to stand the load), and then tap the datastream off the modulated beam.
Ok, so this isn't what is going on - but do any of you see the idea? Would this even be possible? Something tells me that currently it wouldn't be at all practical, if it is possible to some degree. But the idea seems like a fantastic (if unworkable) use of fiber optics - to "carry" electricity and data at the same time...
Ok, I'll stop toking now...
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Hmmm, you're right about the higher elasticity of fiberglass, now that I think about it.
OTOH, we'd still talking about fiberglass composites rather than the types of glass we use for optics, IIRC.
After carefully reading the project page link, I think the author over at wired missed the point entirely. FiberOptics are glass -- low tensile strength, while the core of a transmission line's primary purpose is to provide load carrying capacity in tension. Thus, using fiber optic cable for a transmission line core makes no sense.
On the other hand -- recent advances in carbon composites have resulted in some amazingly good fibers with strength/weight ratios that are hard to believe. Replacing the steel core with carbon composite fibers would allow more current carrying aluminium in the same diameter cable.
The splicing question now makes much more sense -- splicing metal cables is a simple mechanical proposition -- not so with joining composites.
Why don't they use a layer of copper, which has a much higher conductivity than aluminum. The only reasons I see for aluminum are:
Slightly higher tensile strength than copper, but then that's what the steel core is for.
Aluminum exposed to oxygen forms an aluminum oxide (a.k.a. sapphire) passivation layer, then furthur oxidation stops. Scratch through the passivation layer, and a new one forms automatically. Copper doesn't do this.
However, you could plate the copper with a thin layer of aluminum. At 60 Hz, the skin effect should allow the copper to carry most of the current for a reasonably thin aluminum layer.
The other point that is valid is that normally, fiber optics have less tensile strength than steel. However, I assume (since the article really doesn't say) that the core will be an arimid fiber (a.k.a. Kevlar) with a possible plastic or glass core.
I agree with some other posters. Screw that, get buckytubes working. Then you will be able to greatly increase the current carrying part of the wire.
www.eFax.com are spammers
If you read the Wired article, you see a link to the real article. Congrats to Wired for citing their source. Too bad they blew their article, and so did Slashdot. It is not "fiber optics" in the center of the wire. This is *so* *obviously* *wrong*. Fiber optics are glass! Is glass stronger than steel? The real article clearly says that they are "fiber-reinforced composites". That is, newfangled materials that are indeed stronger than steel. Not glass! Have some common sense, people.
So yes, soon, all of California will be addicted to CRAC.
Sometimes, you just can't make this stuff up.
So I guess these power companies should double check the fine print before laying any fiber optics alongside their power lines.
They don't bury the other ones because of heat dissipation needs (High voltage lines can get REALLY hot in times of high system loads and you don't want the insulation melting underground causing a 220KV line to short directly to ground because that would be REALLY bad.)
UPS Sucks
Composite cores aren't going to be a major breakthrough in power distribution. They might be used for unusually long wire spans, as when lines cross rivers. Higher voltages and DC transmission are more promising technologies.
As for fibre to the home, it can be done that way, but the initial enthusiasm of power companies for getting into retail data distribution seems to have subsided, probably because the other broadband players aren't making much money.
Here's an explanation of what happens which will probably be unclear due to my lack of physics lecturing experience:
Don't worry, it was pretty darned unclear. Specifically, this is where you lost me:
Imagine a conductor going in and out of your screen, in the middle.
OK, I can see him. He's got those denim overalls and the funny cap, but I don't know why he's going in and out of my monitor..
As you can see, if the time-constant of the eddy currents in the wire is a lot smaller than the frequency of the power in the wire, skin effect will be pretty small.
I don't normally count my self as stupid, but that made about as much sense to me as Geordi explaining how the deflector dish is going to create a reverse tackyon pulse to break the hold of the tractor beam while negating the subspace turbulance to disrupt the localized positron field surrounding the enemy ships.
I'm not trying to say that your explanation wasn't appreciated (Slashdot could use a few more researched explanations like that), just that it was way over my head, which isn't your fault.
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Isn't California's problem lack of power at the power plants (lack of power plants), rather than lack of infrastructure to carry that power? I think the idea is to provide backup for major power line cuts, which isn't at all the California problem.
ok then your [sic] infringing on my copyright! Could you as [sic] me next time before STEALING my comments for your own?
It's sort of weird... data and electricity sharing the same line -- the phrase "information is power" rings errily true here!!
But, if information is power, and power corrupts, does this mean we're going to have unreliablt data connections over these lines :)
I use to work in the test lab at Burndy Connectors, where we tested connectors for these types of connections. Most of these (99.9%) are compression, or crimp connectors.
... as the link in the original article explains this is one of the many hurdles...
... It could grab a cable and pull both ends with up to 100,000 ft-lbs of force ... and we got up into that range testing these types of connectors. We had big shields to stand behind during these tests ... as the device (cable & connector) under test would/could send stuff flying when it pulled apart.
.2 seconds in duration. Two pulses withing a couple of minutes would raise the temp of the cable to over 100C and turn it black.....
I would think the fiber would have to be quite sturdy to withstand this type of compression
I remember our test (pulling) machine
I remember the crimp had to crimp enough to really grab the steel core (to provide 95% of the cables rated tensile strength). A really good design (connector & crimp tool) could actually exceed the cables rated strength.
Now for some real fun, we use to test grounding grid connectors. Imagine a 10 meter circle of 2500mcm stranded copper cable (about 2.5 inches in diameter; with connectors every 3 meters. We would hook it up to a huge power source (usually a sub-station) and pulse high currrent thru it [I dont remember exactly somewhere around 50,000 amps, but I remember it was in the 5 to 20 megawatt range. The pulses were
-- www.globaltics.net
Political discussion for a new world
California's problem is more of an infrastructure problem based on contradictory laws, many of which seek to avoid the consequences of the laws of nature. Mix that in with corporate and civic oportunism, and there is enough blame to go around to tar and feather everyone.
They have run into the classic "Pick two out of thre problem": Cheap, Reliable, Easy/Fast
They want to have all three, and it isn't there.
Check out the Vinny the Vampire comic strip
"It is a greater offense to steal men's labor, than their clothes"
No, but the Fiber lines are much smaller so you can pack them in. The steel cores are much stronger then they need to be, to limit the amount of sag. Maybe they should try kevlar/nylon mix to support the cables it would be costly but much stronger.
Power transmission has been basically unchanged for years. The last big change was moving to steel core aluminum from copper, and that was a cost issue, not through put. In order to meet future power demands there need to be changes at all levels production, distribution, and consumption. This is the first productive change in distribution I can remember.
As x approaches total apathy I couldn't care less.
Energis here in the UK are already doing something like this. Whilst they don't have fibre optic cores to cables, they took the opportunity (at least initially, they have have moved on now) to string fibre along the earth cables on transmission pylons. (UK pylons have an earth cable at the top to lessen damage from lightning strikes).
The beauty of such a method is that they already have legal rights-of way onto private land where the pylons may be situated.
(If you're REALLY bored you can visit this website for some pylon pictures!)
Links for goatsephobics: www.energis.net www.pylonofthemonth.co.uk
Matt
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"The nice thing about this is you don't have to replace the whole line, just the lines with sag," Rodriguez said. "For a few hundred thousand dollars you can fix an existing line in a few weeks time so it wouldn't be a bottleneck."
So they're only replacing some of the lines, wouldn't that mean it would be impossible to transmit data, since only some of the lines are being replaced?Still, it provides a roadmap for the future for full conversion, I just think that 2003 is probably way too early to expect data transmission
You crazy man? You piss off supahfly!
If you increase efficiency of the lines, more power will get to the customers.
In the article they say that 30,000 megawatts are lost due to line sag. Though I'm sure that such losses can never be completely negated, they can be minimized. Yes, california needs more generating capacity, but that doesn't mean it won't help to waste less of that energy in transmission.
as I reread your comment, I'm not even sure you read the article...
It looks as though the data transmission isn't high on the agenda. The initial plan is to only replace bits of lines that are sagging, so it will be a good long time before there's enough contiguous cable in there to form a backbone.
Anyone know the operational lifetime of steel cored cables?
If you were blocking sigs, you wouldn't have to read this.
Maybe you should take the time to read the article. There's an optimum cable diameter above which wind and ice becomes a hazard. The can't make it thicker, but they need to get more current carrying aluminium in that diameter as possible.
I do agree with you about the data though, it's more of an "Oh gee, I guess we could do that," sort of consideration.
Anyway, they'd be better paying the up front cost and burying the whole damn lot. Then they could make it as thick as they like, and lay some nice new fibre in there while they're at it. No, wait, that would require a long term viewpoint, like thinking 2, maybe 3 years into the future... ;)
If you were blocking sigs, you wouldn't have to read this.
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Scientists restrict study to entire physical universe; creationist
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Scientists restrict study to entire physical universe; creationist
If you're going to run optical fiber along a power cable, it would make more sense to replace one of the outer aluminum strands with a jacketed bundle of fiber. That puts the fiber right where it's easy to work with, instead of in the structural center of the cable beneath the conductors.
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Scientists restrict study to entire physical universe; creationist
Imagine a conductor going in and out of your screen, in the middle. Now assume an increasing current through that conductor, going into the screen. Since the magnetic fields from a conductor form circles around it (by the right-hand rule), you'll have a magnetic field going clockwise around the conductor.
You can assume that this current flows only on the very surface of the conductor, but that would imply an arbitrarily small depth and a rather large resistance. This is pretty obviously not the case in reality, so it's worth analyzing the situation to see what really happens. If you have a step-function increase in current along the conductor, you'll have a lot of current flowing in the surface layer, a big magnetic field around the outside, and a smaller current in the bulk of the conductor with a smaller field there. The bigger field tries to penetrate the conductor, along with its associated current. It can't do this all at once; as the field flows into the conductor it sets up eddy currents like smoke rings blowing down a pipe. These currents flow in the forward direction (the direction of the change in current) on the outside and in the reverse direction (against the change in current) on the inside. The eddy currents have to fight the resistance of the wire, and they decay exponentially with time. After a few time constants, the current is flowing pretty much evenly through the whole wire.
As you can see, if the time-constant of the eddy currents in the wire is a lot smaller than the frequency of the power in the wire, skin effect will be pretty small. The construction of the wire has an effect, too. Since the time-constant of the eddy damping is a function of the thickness of each individual piece of conductor, winding strands in thinner shells will reduce the skin effect. The trapezoidal arrangement of conductors in the aluminum-clad-steel wires may be designed for this purpose (or maybe it was just a convenient way to squeeze more aluminum into the cross-section than a single layer of pie-shaped wires would have been; my guess is, a little of both).
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Scientists restrict study to entire physical universe; creationist