High-Temperature Superconducting Cable Technology

8/2/2019 High-Temperature Superconducting Cable Technology

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High-temperature SuperconductingCable Technology



1. IntroductionBecause superconducting cable is compact and can transmit alarge amount of electric power, it can utilize more effectivelycongested underground space where a lot of pipings and otherunits already exist.

Superconducting cable also makes overall construction costsmaller than that of conventional cable.

In the development of Bi-based superconducting wires, a newlydeveloped pressurized sintering method allowed mass

production of a low-cost long wire with a high critical current.The critical current of supercon-ducting wire exceeds 130 A perwire (4 mm x 0.2 mm),and it has an increased tensile strengthof 140 MPa (atRT), which is an important mechanical propertyfor



From 2001 to 2002, Sumitomo Electric Industries,Ltd. (SEI)successfully conducted a long-term test of a 66kV, 1 kA, 114MVA class superconducting cable in collabo-ration with Tokyo

Electric Power Company (TEPCO) and the Central ResearchInstitute of Electric Power Industry (CRIEPI) at CRIEPI’ sYokosuka Laboratory, to verify its practical performance and toidentify problems.

Buoyed by these results, SEI is aiming for theearly commercialization of practical superconducting cable, andis participating in a superconducting cable demonstrationproject (Albany Cable Project) in the United States.



2. Superconducting Cable Construction

The conductor is formed by laying the Bi-basedsuperconducting wires in a spiral on a former. PolypropyleneLaminated Paper (PPLP) is used for the electrical insulationdue to its good insulation strength and low dielectric loss at

low temperatures, and liquid nitrogen works as a compoundinsulation in addition to coolant.On the outside of the insulation layer, a super-conducting wireof the same conductor material iswound in a spiral to form ashield layer.Each shield layer of each core is connected to each other at

both end of the cable, so that an electrical current of the samemag-nitude as that in the conductor is induced in the shieldlayer in the reverse direction, thus reducing the electro-magnetic field leakage outside the cable to zero.



Structure of SC cable



Three cores are stranded together, and this is placed inside adouble-layered SUS corrugated piping. Thermal insula-tion is placedbetween the inner and outer SUS corrugat-ed pipings wherevacuum state is maintained to improve the thermal insulationperformance.

The superconducting cable line construction cost, calculatedassuming that current construction tech-niques are used andcooling system is in every 5 km, is likely to be much lower than thecost of constructing a new conduit line of a conventional cable.

From the above reason, the superconducting cable is expected tobe cost competitive.



3. Advantages of SuperconductingCable

compactness and High Capacity

Low Transmission Loss and EnvironmentalFriendliness

Low Impedance and Operatability



Compactness and High Capacity

Superconducting cable can transmit electricpower at an effective current density of over100 A/mm2 which is more than 100 times thatof copper cable. This allows high-capacitypower transmission over the cables with morecompact size than conventional cables, which

makes it possible to greatly reduceconstruction costs.



Compactness and High Capacity







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High-Temperature Superconducting Cable Technology