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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.
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".
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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.
So yes, soon, all of California will be addicted to CRAC.
Sometimes, you just can't make this stuff up.
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
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.