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Science Technology

The Fiber Age Meets The Power Grid 94

Posted by timothy from the not-quite-how-it-sounds dept.
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.
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The Fiber Age Meets The Power Grid More

The Fiber Age Meets The Power Grid

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  • And how long would it take to fix? (Score:1)

    by Anonymous Coward
    I had a power cable come down on my house a week ago. How long would it take to fix a fiber optic core line? Backbone fiber is too important to keep above ground, so this would only be cool for small area distribution. Neat idea though

  • Re:fiber optics? Try COMPOSITE FIBERS! (Score:1)

    by Anonymous Coward
    You are incorrect and inconsistent. Ignoring geometry, high stiffness = high modulus. Carbon fibre has a much higher elastic modulus than glass fibre, which is why it is used in applications requiring high stiffness. Carbon fibre is also brittle - the tensile strength of carbon fibre is generally a bit lower than glass fibre.

  • now, not 2003 (Score:2)

    by Anonymous Coward
    I work for Corning Cable Systems [corning.com], 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.
  • You might want to read the fabolucious article..

  • Re:fiber !=power ? (Score:3)

    by bwulf ( 325 ) on Monday June 04, 2001 @06:28AM (#178442)
    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.
  • Do they burry the high voltage lines?

  • Wow, that's fresh! (Score:3)

    by sphealey ( 2855 ) on Monday June 04, 2001 @06:47AM (#178445)
    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
  • This wont help the power problem? Shocking...
  • The US is still lagging largely behind the rest of the world, as usual...

    For more than 8 years, Hydro-Québec [hydroquebec.com] 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...

    --

  • 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.
    Actually, no. With AC current, cable capacity is not a function of it's cross-section area, but only of it's cross-section perimeter, since AC current only travels at the surface of the cable.

    This is why on big transmission lines, each phase is carried on two or four wires separated by spacers.

    --

  • No, we'd rather have the power-line towers fall over and black-out huge areas when the weather turns bad .. Yay..

    --
    Delphis
  • 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.
  • 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.

  • Tamper-resistant? (Score:3)

    by KFury ( 19522 ) on Monday June 04, 2001 @06:27AM (#178452) Homepage
    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
    --
  • I know I have heard about replacing the current tension wires (the top wires on the tower poles) with steel + fiber bundles. Seems to me that it would be a whole lot easier to deal with that wire (which isn't energized) than dealing with the wires which actually carry current.

  • NY Times article. (Score:3)

    by Matt2000 ( 29624 ) on Monday June 04, 2001 @08:44AM (#178454) Homepage

    The NY Times had a pretty good article [nytimes.com] about this recently too.
  • Actually, power consumption is down 7% per capita in 2001 over 2000. So, it's reall not Fat Chance.
  • The article misses the point. They do intend to use composite fibers.

    What they are trying to convey is that power transmission companies are considering using the same type of fiber-glass strength member that is currently being used in fiber-optic data cables as opposed to a steel strength member. This will make the cables lighter and sag less. Your point about composites is well taken, but carbon-fiber is a bit too expensive for applications such as this. Fiber-glass with intermediate strands of kevlar would probably work very nicely, which oddly enough is exactly how Siecor (and others) makes their fiber-optic cables.

    If you go to the link that Wired refers to [usc.edu] you will see the following:

    Approach: The simplest solution is to increase the volume of the aluminum strands without increasing the assembly diameter. This can be achieved by replacing the steel strands with fiber-reinforced composites that are more than twice as strong and far lighter. Thus, less material is needed to carry loads, and more Al can be incorporated into the design. USC is teaming with several industrial partners (Goldsworthy, SCE, Southwire, and ORNL), to develop a design and prototype called CRAC (Composite Reinforced Aluminum Conductor.)

    So yes, they really do intend to use composites and the though of putting actual data-transmitting fibers in the power cable is being overlooked. Justifiably so, I might add. There is already plenty of data transmission capacity between SoCal and NorCal and the costs aren't really in laying the fiber in the first place. Lighting the fiber gets way more expensive in the end.

    This is really just another example of bad journalism.

  • It's not quite the same thing, but there are some interesting tensile-strength comparisons - including a type of glass fiber - here [owenscorning.com].

  • If you want to be pedantic, it's spelled Aluminium

    Sometimes, but it's certainly not spelled "alluminum" and "steal" was just laughable.

  • it's not even spelt correctly in your dictionary

    You mean "spelled", right? Sorry, couldn't resist.

  • Alluminum pound for pound is stronger than steal.

    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".

  • It all depends on where you are...

    M-W:
    Main Entry: aluminum
    Pronunciation: &-'lü-m&-n&m
    Function: noun
    Usage: often attributive
    Etymology: New Latin, from alumina
    Date: 1812
    : a bluish silver-white malleable ductile light trivalent metallic element that has good electrical and thermal conductivity, high reflectivity, and resistance to oxidation and is the most abundant metal in the earth's crust where it always occurs in combination

    Oxford:
    aluminium n. (US aluminum) a silvery light and malleable metallic element resistant to tarnishing by air. Symb.: Al. aluminium bronze an alloy of copper and aluminium. [aluminium, alt. (after sodium etc.) f. aluminum, earlier alumium f. ALUM + -IUM]

    So the spelling of Al depends on the spelling of color(colour) and theater(theatre)...
    --
  • Guys, this doesn't mention anything about fiber-OPTIC stuff. It's all about fiber-reinforced composites--you know, like fiberglass?? Does anyone read the freaking stories before posting these headlines?
  • 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 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 /. - 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.

    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...

    Worldcom [worldcom.com] - Generation Duh!
  • It's been a few years since I worked in this area (about 5) so advanced materials may have changed some. It is often a misconception that carbon fiber is stronger than fiberglass. It is (was) not. Glass fibers (S-glass) have a higher modulus of elasticity than carbon fiber (cheap E-glass is lower). Carbon fiber is primarily used for its stiffness, not its strength.

    SuperID
    Free Database Hosting [freesql.org]

  • Wow, you sound informed ... "good karma" ... kind
    of like how all Californians eat only granola and
    nuts and drink bottled water.

    Oh, wait, everyone else is doing that now, too.

    DAMN THOSE CALIFORNIANS!
  • 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.

  • fiber optics? Try COMPOSITE FIBERS! (Score:4)

    by J.Random Hacker ( 51634 ) on Monday June 04, 2001 @06:39AM (#178468)
    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.

  • I'm reading the article, but how does fiber optic give electricity?

  • How about titanium?

    Lighter than aluminum, stronger than steel. Ask Apple.

  • 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.
  • Several people have pointed out the price difference between copper and aluminum. I ignored that difference because:

    a) The cost of the power lost vs. the delta cost of the conductors has changed from when the move to aluminum was made.
    b) The cost of simple AL/CU/Fe cables vs. these new AL/Fiber cables should swamp out the increase. In other words, AL/CU/Fe would probably be cheaper than AL/Fiber.

  • First of all. You aint runnin no data through the core. Splicing fiber is already difficult without a wrapper of high voltage current. Second, why not just make the wires thicker? Alluminum pound for pound is stronger than steal. If you need more alluminum, just make the thing all alluminum. Maybe this wont work, but dont even joke about running data through this thing.
  • Glass is still brittle. While in a lab the higher tensile strength might be interesting, it is of little practical benefit for most common applications.
  • If you read the Wired article, you see a link to the real [usc.edu] 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.
  • This is being done in Spain since 10 years or so. In fact, the power companies tried to become ISPs, and the CNMT (National Telecom Market Comission) ruled them out, they said they would severely disrupt the telecom market.

  • California's power addiction (Score:4)

    by BobGregg ( 89162 ) on Monday June 04, 2001 @06:46AM (#178477) Homepage
    According to the research link [usc.edu], today's wires are known as Aluminum Conductor Steel Supported (ACSS) wires. However, USC is working with the industry to develop these fiber-composite wrapped wires, which will be known as Composite Reinforced Aluminum Conductors.

    So yes, soon, all of California will be addicted to CRAC.

    Sometimes, you just can't make this stuff up.

  • There is a company that has been running fiber in the core of the ground wire on top of high voltage transmission lines for a number of years, it is NEON Communications [neoninc.com] (http://www.neoninc.com). In fact, one of our OC3s runs from Portland, ME to Boston, MA via this link, so the bits that make up this posting are probably transversing such a line.
  • I stand corrected. No need to be rude, however.
  • depending on the contracts involved, this might not work in the US. Recently [slashdot.org] a bunch of telcos get slammed for running data lines over land leased from railroad operators. Apparently, the right-of-way for a railroad track does not confer any right of way for data lines, which had to be licensed separately from each property owner along the route.

    So I guess these power companies should double check the fine print before laying any fiber optics alongside their power lines.

  • No.. They don't bury the high voltage lines (they may bury the 220V lines instead of having light poles).

    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.)

  • Typical Wired confusion. There are two unrelated concepts here. One is using some kind of composite fibre (probably something like Kevlar) to carry the weight of high-tension transmission lines. The other is using fibre optics alongside, or wrapped with, distribution lines going to houses, which is safe electrically because glass fibre doesn't conduct electricity.

    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.

    --
  • Both I think.

    Southern California has power but there is a bottleneck somewhere between LA and San Fran (I know, that's about 500 miles apart, not exactally precise)

    Northern California is plagued by lack of rain (hydro), maintenance on current plants, huge demand (biggest factor) and the worst deregulation procedure ever. Funny how in PA, NJ, TX, and other states that have deregulated they haven't even seen a hint of a crisis. In fact, they now have choices in how "clean" there power is (coal, hydro, wind, bio-mass, gas, etc) and have seen rates drop slightly due to open competition.

    Normally, power plants only transmit power about 300 miles (I think, correct me if I'm wrong) after that losses become too big. But I read in the U.S. News and world report, that b/c prices are so high, some power is being transmitted from as much as 600 miles away. (disclaimer, I don't know how accurate this info is, if someone has any more insight, please post)
  • It keeps saying fiber is thinner than steel. Do they mean that it has a higher tensile strength than steel, allowing less cross-section to carry the same load? Is this true?
  • TYCO or Tycom makes cable to do just that undersea. The cables just happen to power the repeaters on the line instead of homes. There are 5 to 10 fibers woven in the middle of the steel core which is then sealed in plastic. So I wouldn't call this an earthshattering breakthrough.
  • 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.
  • This is pretty cool, sort of reminds me of running data over conventional electrical lines. [ecommercetimes.com] By a German power company [rwe.com] are planning to do this summer.

    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 :)

  • From the article "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 :)

    I think it's a case of an author writing an article on a subject on which they know very little. The 'sag' would include all high tension lines. The lines on the 'towers' 'sag' because of being highly susceptable to contraction and expansion and the distance between the towers. The 'little lines' he was talking about, I guess, in saying 'they'd branch off'...wouldn't actually. He probably means intermediate lines, carrying much lower (albeit higher than the normal 12k or so transmission lines) voltage stepped down at a substation. They wouldn't have any fiber in them at all. The fiber would be terminated at the substation or connected to another fiber run, etc. (The author thought maybe they were going to run fiber right on through the transformers? hmm) This really is a very OLD topic. Other companies, like AEP, etc, have been working on using their high power transmission easements for fiber. They were talking about this (fiber core) several yeras ago.

  • Funny how in PA, NJ, TX, and other states that have deregulated they haven't even seen a hint of a crisis. In fact, they now have choices in how "clean" there power is (coal, hydro, wind, bio-mass, gas, etc) and have seen rates drop slightly due to open competition.

    I think you'll find that's due to a couple of reasons (though deregulation is different between NY, PA, etc.) First, there's plenty of power here, and transmission capabilities in the PA-NJ-MA grid. Second, at least here, the incumbant utilities weren't forced to buy at spot prices. They sold transmission facilities like in CA, but they can have contracts for power purchases.

    Normally, power plants only transmit power about 300 miles (I think, correct me if I'm wrong) after that losses become too big. But I read in the U.S. News and world report, that b/c prices are so high, some power is being transmitted from as much as 600 miles away.

    Bingo. and that's what the politicians like Davis forget to tell everyone when he says how much it costs to buy power from TX. Prices are already high from the producers in CA. If you have to buy it long distance, they have to 'ship' a LOT more than you end up getting. Let's say you want 5000MW from TX. Hell, they may have to ship 10000MW or more? They ain't going to give that to CA for free. So even if the prices were the same, it's going to cost a LOT more for that power all the way from Texas. If there was a lot of surplus, that might not be the case, they'd probably be willing to take a hit just to sell the power. But in these days, they just don't have to.

  • The dream of being able to send leathal voltages back down the data line and fry the Script Kiddie's Machine as they tap at your ports is here!

  • ...In addition, for this substation testing
    1) this huge copper loop was set on 3/4" plywood on sawhorses, and held to the plywood with pretty hefty U-bolts. All this inside what looked like a huge concrete garage (single 2.5 story room open on one side)

    2) We were in a facing blockhouse about 60 meters away with the control & data recording equipment.

    3) when the current was pulsed, it sounded like a stick of dynamite going off.

    4) the most impressive thing to me, was that the pulse (AC) would try and make the copper loop a perfect circle (?) and this translated into a physical force which, by the third and final pulse, ripped almost half the U-bolts out and up [2 1/2 stories] to embed themselves in the ceiling.

  • Compression Connectors (Score:4)

    by ReidMaynard ( 161608 ) on Monday June 04, 2001 @07:03AM (#178493) Homepage
    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.

    I would think the fiber would have to be quite sturdy to withstand this type of compression ... as the link in the original article explains this is one of the many hurdles...

    I remember our test (pulling) machine ... 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.

    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 .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.....
  • It's over 10 years since I did this and E-M was never my string point but ISTR that at 50Hz (Yup I know the US uses 60) the useful current was carried in a skin of about 1cm. Therefore, I would suspect that the principle problem is cross-section to wind.

  • For the future, not now! (Score:3)

    by Alien54 ( 180860 ) on Monday June 04, 2001 @06:29AM (#178495) Journal
    We need to think of this as a infra-structure solution for the future, not for now. It would take too long to put in place to be able to use as an immediate solution for the current California solution.

    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 [eplugz.com] comic strip

  • Well, whatever these people are doing, I remember a prediction from a few years ago. It seems the power company has to control it's substations remotely, but all that electricity tends to corrupt data over copper. As a result, many of the power companies installed fiber, which is of course, underutilized by their low bandwidth needs. It was predicted in the article ( I think it was Wired, back in '95 or so) that power companies would become strong providers of broadband internet service thanks to their large fiber network.

    Haven't heard anything since.

  • Yes it is - glass has a higher tensile strength than steel. Don't just trust me though, look it up. Remember that tensile strength is not equal to toughness. Glass is nowhere near as tough as any steel, if you hit a plate of steel with a hammer it will dent, if you hit plate glass it will shatter. With fibres you need to break them one at a time, so toughness is not an issue with glass fibre.
  • I'm surprised that the industry changed from copper to aluminum, considering the electronics/microchip manufacturers are just switching from aluminum to copper. I thought the conductivity benefits of copper outweighed the cost drawbacks. I guess not...
  • optics are glass! Is glass stronger than steel?

    It has a higher tensile strength, yes. This means, for example, you could hang more weight from a fiber strand than you could from a steel strand of the same weight. Since fiber is much lighter than steel, this seems obvious. People seem to miss the weight piece of the equation, though.
    --
  • But your carbon/steel wire will cost up to 100 times what the steel wire will cost. Carbon fiber can be made to ~1000 ksi but would shatter like glass if struck, and would cost and unreal amount of money.
  • Is glass stronger than steel?

    It can be, depends on grade of steel and grade of glass. But, the steel will be much cheeper.

  • 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.
  • 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 ...
    aluminum oxide passivation layer ...

     They used to use copper, but changed for two reasons:
    1) cost
    2) weight

    Find a trick to make copper light and cheap, and I'm sure they'll go for it.
  • Ultimately though, the solution is to decrease demand by increasing efficiency at the consumption end (i.e. turn down the damn air conditioning). Fat chance.

    Californians, on average, use 15% less power than people in other states. There is already a strong conservation ethic at work here. The problem is that there hasn't been a new power plant built in the state for ten years, and in that time we've had considerable growth. We need more generating capacity, period.

  • 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.

  • Energis [energis.net] 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 [pylonofthemonth.co.uk] for some pylon pictures!)

    Links for goatsephobics: www.energis.net www.pylonofthemonth.co.uk

    Matt

  • How long to get full data? (Score:3)

    by TimeTrip ( 254631 ) on Monday June 04, 2001 @06:24AM (#178507) Homepage
    From the article
    • "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 :)

  • Let's look at this objectively.

    We are looking at putting a few fiber optic strands that are difficult to interconnect. Each fiber optic strand can carry a few giga-bits of transmission capacity. It is only going to be used along high power transmission corridors.

    I really don't see us getting a lot of bandwidth or getting it in the places that we need. This looks like another "Wired Wet Dream". Though it would be interesting to use the fiber to interconnect the information backbone for the grid. Given that California ISO spent a fortune on a fiber backbone, I could see this as a benefit.

  • 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...
    • Isn't California's problem lack of power at the power plants

    Because they're turned off for political and financial reasons, not because they can't generate the power. They do need some extra capacity, but they've been adding generator capacity faster than transmission capacity, and need to get caught up on the latter before they can really crank up the former.

    What I like about this idea is that it's increasingly efficiency, which is always good. Ultimately though, the solution is to decrease demand by increasing efficiency at the consumption end (i.e. turn down the damn air conditioning). Fat chance.

  • 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?

  • Correction to myself - I didn't mean increased efficiency in California, I meant globally. Fat chance. ;)

  • Re:Why not use copper (Score:3)

    by Rogerborg ( 306625 ) on Monday June 04, 2001 @06:56AM (#178513) Homepage
    • Why don't they use a layer of copper, which has a much higher conductivity than aluminum.

    Same reason they don't use gold or platinum... Wires used to be copper, though, before economics changed the laws of physics.

    Anyone know if aluminium runs hotter (i.e. more transmission loss) than copper? That wouldn't be a problem for utilities, they'd just crank up the meter price to cover it. ;)

  • Re:stupidest thing I've ever heard (Score:4)

    by Rogerborg ( 306625 ) on Monday June 04, 2001 @06:40AM (#178514) Homepage
    • Second, why not just make the wires thicker?

    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... ;)

  • so irritating...

    they answer your question, completely, totally, and effectively, on the first page of the article.

    make some kind of effort.
  • in the defense of the researchers' efforts, isn't this primarily positioned to be a low down-time/lower-cost fix for more efficient redistribution of power across longer distances?

    the main upside, as i read it, is that for a couple hundred thousand and a few weeks of work, they can make a 15% increase in the normal capacity of a high tension wire, with much higher peak carrying capacity.
  • the beautiful part is that this plan is thinking 2-3 years into the future. i'd settle for them just thinking ..
  • I thought the spelling was "Aluminium". Then again, what the hell do those people in England know about the english language.
  • 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?
    Depends on where you are. If you're in the middle of the Si Valley, then no, you won't be able to benefit that much from this potentially very fat pipe. But if you want to set up your new data center in Gorman (town about 60-70 miles north of LA), then you may be able to tap into this bandwidth. Of course, like you said, right now is just the stage where they brace up a collapsing system, not when they upgrade the entire grid.

    Besides, do you really want your bandwidth from SCE anyways?

  • As Bill Maher said, "Don't feel sorry for the Californians, they can get power all day long from the sun." Really though, get your neighborhood together, have a meeting and just buy a fuel cell about the size of a semi's trailer, and start saving money. Have the local Boy Scout troop be put in charge of restocking the H2... Forget those darn power cords that the power company want you to suckle milky electrons through and be indie.
  • (That was actually a back-handed complement; your post had errors no worse than the Wired article, which means that you could easily beat their level of accuracy and professionalism if you wanted to. What this says about Wired is not something I'll speculate about here.)
    --
  • 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.
    Except that what I was trying to describe is real physics, and it's not balonium, it's supposed to be understandable and quantifiable. Good thing I don't teach physics for a living, I guess.

    It's said that you lose about half your audience with each equation you put in a piece. This may be true for the public in general, but maybe not for Slashdot... yet Taco et alii have decided not to allow the use of the <sup> tag and other things that are needed to write even elementary exponential equations in a fashion that displays clearly. What can you do?
    --

  • This is why on big transmission lines, each phase is carried on two or four wires separated by spacers.
    Maybe one of the reasons, but the other one is that the multi-wire configuration has lower electric field strengths and less corona losses than a single conductor does.
    --
  • In the ZDNet article [zdnet.com] cited for the Slashdot story, it's made clear that the problem was that the railroads did not own the sub-surface rights where the cables actually ran. I quote:
    ... in many cases railroads bought the surface rights from original property owners to lay tracks. But those rights didn't include so-called subsurface rights, which traditionally allow for activities such as mining or oil drilling.
    Next time, read a little more carefully. It wouldn't do for you to have as much egg on your face as a certain Wired author and his editor, would it?
    --

  • Moreover, what's the point? (Score:3)

    by Spamalamadingdong ( 323207 ) on Monday June 04, 2001 @01:34PM (#178525) Homepage Journal
    If you are replacing structural steel in a power line, you'd want to replace it with something that is stronger and lighter (Kevlar or graphite or maybe Spectra). What's the point in using a core material that's not as strong (glass is weaker than graphite)? It increases the weight, reduces the amount of aluminum you can put in the wire, and reduces your advantage.

    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.
    --

  • Actually, no. With AC current, cable capacity is not a function of it's cross-section area, but only of it's cross-section perimeter, since AC current only travels at the surface of the cable.
    Unfortunately, that's a rather large over-simplification of the actual physics. Each material has a characteristic skin depth for a particular frequency. This skin depth is determined by the magnetic and electrical characteristics. Here's an explanation of what happens which will probably be unclear due to my lack of physics lecturing experience:

    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).
    --

  • Um almost. There was an idea for supplying broadband through the power network by sending a high frequency through the power cable. Unfortunatly it was dropped due to the low bandwith available / cost and ADSL/Cable modems arriving first.
  • If you want to be pedantic, it's spelled Aluminium
  • Damn phonetic spellers! Chop off their fingers, the lot of them.

  • Due to the high voltage, the NSA guy who splices this line [slashdot.org] will be in for a rather shocking experience. Talk about instant karma...

  • I doubt we (United States) would be without enemies, but I have to admit that our government/intelligence agencies seem to stir up more trouble than they solve.

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