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Joined: Oct 2002
Posts: 482
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Zapped Offline OP
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Just ran across this article and would like to know if anyone here can shed some more light on this subject. The picture at the bottom of the article is quite interesting - they show the size of the superconductor as compared to the same ampacity conductor in copper.

http://spectrum.ieee.org/jul08/6428

Any thoughts, comments, or further info on this development?

Joined: Jul 2004
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G
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Scientific American had an article about this several years ago. They see the biggest use being in cities where underground duct "real estate" is limited and being underground it is easier to hold the 60K temperatures needed.
They can get a whole lot more power in a small duct this way.


Greg Fretwell
Joined: Jan 2005
Posts: 5,316
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To a certain extent, I think this development is inevitable. There's no denying that we need ever-increasing amounts of power - and that we've reached the practical limits of wire size and voltage.

It's also yet another suggestion that the days of the single, massive generation plant are gone forever.This isn't some feel-good greenie wish for "co-generation;" it's reality. For a variety of reasons, we better get used to the idea of receiving power from a variety of sources, of varying scale.

What's that mean for you and I? It means we need to really understand bonding, LOTO, and over-current protection principles. It means that the top part of our panels will soon be as cluttered as the area near the breaker terminals.

On the "political" level, it means we can no longer expect generation / distribution equipment to be located far away and out of sight.

Finally, it means that more of us will have to learn to work on systems well beyond 600 volts. "Power quality" and "corona" are terms that will no longer be trivia questions in apprentice courses.

Joined: Mar 2005
Posts: 1,213
S
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Long-hault superconcucting transmission line will still face inductive and capacitive losses, no freebie there. Maybe supercapacitors combined with superconductors? Ah well, one can always dream!

Superconductors do saturate at a point, and can only carry so much current, but because there's no resistance, voltage drop and transmission efficiency is not a limiting factor. Transmission line efficiency will jump to nearly 100%.

The problem with superconductors is that even "high temperature" superconductors still need to be cooled by liquid nitrogen. (They're high temperature only when compared to those other superconductors that need cooled with liquid helium.) Sounds like the wires they're using here still need to be held at temperatures that would freeze liquid nitrogen, though.

The cooling is rather counter-intuitive; it's not to cool heat generated by the cable, as electrical resistance is so close to 0 that no heat is generated. (Superconducting wires would not require thermal derating for raceway fill.)

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Zapped Offline OP
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The cooling requirement brings up and interesting factor. HOw will the cost of maintaining the cooling system(s) factor into the overall cost? When this is factored in, will this new technology really be more efficient and cost effective than a large copper wire?

What about when, inevitably, the cooling system fails somewhere in the grid? Disaster, or easily remedied maintenance?

It's not that I fear change. In fact, far from it. I believe whole-heartedly in moving forward and exploiting our collective progress in technology. I'm just curious...

Joined: Jul 2004
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Originally Posted by SteveFehr
... as electrical resistance is so close to 0 that no heat is generated.

A minor technical point: The resistance is actually zero, not just "close to 0." You can induce a current in a ring of superconducting wire, and it will retain the current for forever, because there is no resistance.

Joined: Mar 2005
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S
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Yes, but not for high temp superconductors. All known high-temperature superconductors are Type II superconductors in which vortices form in the electron superfluid, which gives it a very small resistance. (Small enough to be negligible by any real-world metric, but important for laboratory results.) There is also some resistive loss associated with the typical inductive/capacitive reactance when used as a transmission line, I don't see how superconducting lines can escape that.

Proper superconductors don't suffer the vortices. Lab experiments on superconductors suggest a current induced in a superconductor will continue on for 100,000 years. Calculations for some are in the tens of billions of years: if you get the current flowing, it will continue until the end of the universe.

Originally Posted by Zapped
What about when, inevitably, the cooling system fails somewhere in the grid? Disaster, or easily remedied maintenance?
At this point, I don't see it anywhere close to cost effective. But with, what, 10% transmission line loss and fuel prices the way they are... maybe a few $billion is a drop in the bucket?

If coolant is lost and the critical temperature is exceeded, the superconductor ceases to superconduct and becomes a fuse that will very quickly blow. I'd imagine the damage would be isolated to a short section of line.

Joined: Jul 2004
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G
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I think these issues are why the SciAm article said the most likely use would be short runs in big cities where they simply don't have the duct space to run as much copper as they would need for the load.
I am sure there would have to be an array of thermal sensors and monitors that trip out the conductor if the cooling fails.


Greg Fretwell
Joined: Oct 2000
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Maybe the HVDC Interties (High Voltage Direct Current Transmission Circuits) will benefit more from the usage of the Conductors, than the standard HV 3 Phase AC Transmission Circuitry.

I do not know too much about these DC Transmission Circuits, other than they are rectified from a 3 Phase 3 wire source, and use an Earth-Ground "Return" (Opposite Polarity via Earth / Dirt).

I don't even know if the Earth-Return is Positive or Negative Polarity!!!

Whatever Polarity it is, the "Opposite Side" is hung via Two (2) sets of Parallel Conductor bundles.
In other words, each Pole has Two or Three Parallel Conductors hanging from each Insulator, with Two Circuits per Pole (Two Insulators hanging per Pole).

Looks like a normal single circuit 345 KV 3 Phase 3 Wire Transmission Circuit, only with 2/3 of the Circuit!!!

We have pictures somewhere on ECN of these Animals.

Question: Even if used on AC, would there need to be additional Conductor cooling provided, to anticipate for the Inductive issues of the Transmission Circuitry?

Seems like a "wide" variable when it comes to Reactive Power values in long distance heavy Load Transmission Circuitry.

The Technology might be more suited to applications such as Dry-Type Transformers and Motors, where heat values and Power Factors can be more closely estimated.

I would like to gain more knowledge regarding this Technology.
Remember it back in the late 1980's, early 1990's when it became known in the public sector, and I studied it only as far as the basic theory - then pushed it to the back in pursuit of other stuff (Quantum Theory of Fields, Computer Technologies, trying to make better / more improved practical jokes, etc.).

Would like to learn the advanced tech. stuff - and as mentioned by someone else regarding a "Super Capacitor", maybe the "Super Conductor" its self will act as a "Super Capacitor" too!
If there are minimal Series R2 losses in the Conductor, maybe there will also be minimal Series Xc KVAR, and possibly minimal Capacitor drainage - keeping the Xc more steady in the Conductors.
The Parallel Fields will still be an issue, but maybe these can be stabilized within Cable formers, twisted pairs, and encapsulated conductors.

If there was a way to almost eliminate the value for a given circuit's charge to external entities - more precisely, Earth Ground, then the technology might work out overall!

When I first heard about the technology + studied it, it appeared as if the intent was something like "perpetual motion", so I kind of lost interest in the "Snake-Oil Concepts".

By this I mean the proposed information was oriented towards:
"Initially shoving / moving charges, with no loss of kinetic inertia (due to no internal resistance), with the ability to produce constant output work without adding additional energy"

If the above is "do-able", please let me know of which Planet this physical science is a reality, and I will begin travel plans to go observe it first hand!
Just need a Vehicle capable of Interstellar Transportation, which may also travel greater than 300,000 KM / s, and the Transportation Company accepts Visa Credit Cards (or a post-dated check).

If the above physical sciences are do-able on this Planet, please explain how to create energy from nothing!

All joking aside, I would like to study the more advanced areas of the technology, and its applications to Alternating Currents of Low Hz (25 Hz to 20kHz).

Scott


Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!
Joined: Mar 2005
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The capacitive and inductive losses with superconducting cables are not within the conductors themselves, but induced on the environment- capacitance between the cables and ground, and magnetic fields inducing currents in the earth, towers, other wires, etc- all conventional conductors that would have a resistance associated with the induced current, and would thus represent some "real" transmission loss, even though reactive current in a superconductor would still be ideal and lossless.

DC transmission is an extremely interesting idea! Given that so much equipment now is DC... I wonder if there is a future for DC power distribution? If we can mass produce cheap room-temp superconducting wire, you could probably power an entire house at 12VDC off a #24 wire. The difficulty lies in voltage conversion; it would still be economical to use high voltages for long distances to decrease cable size.

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