JPH09180553A - Former for high temperature superconductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To hold flexibility while a superconductor can be cooled directly by a refrigerant, by forming a former with its material as a copper spiral band. SOLUTION: In a superconductive cable comprising a former 1, superconductor 2 and an electric insulation layer 3 successively from the center, the conductor 2 is formed by helically winding a superconductive wire, coated with a silver sheath, around the periphery of the former 1. Here, the former 1 is formed into a pipe shape by helically winding a band-shaped unit of copper material, the band-shaped unit is wound by opening a space 4 between the adjacent windings. When a refrigerant (liquid nitrogen or the like) is circulated inside a spiral band, the coolant flows out in the peripheral direction from this space, the superconductor 2 can be directly cooled, also flexibility can be provided in the cable. The former 1 is of copper, so that it can be utilized as the bypass of a current, also electrocorrosion with the conductor 2 can be suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductor former forming a high temperature superconducting cable.

[0002]

2. Description of the Related Art As a high temperature superconducting cable, a former, a superconducting conductor, an electric insulating layer, which form a refrigerant flow path in order from the center
Some are equipped with magnetic shields and heat insulation tubes. Some cable formers use stainless steel pipes or aluminum pipes. In addition, there is a high-temperature superconducting cable that uses an aluminum corrugated pipe to make it flexible (53rd 1995 Spring Low Temperature Engineering / Superconductivity Society Preliminary Report: p164).

[0003]

However, all of the above-mentioned formers are pipe-shaped, and the refrigerant filling the inside thereof does not directly contact the superconducting wire around the former. That is, the superconducting wire is cooled through the heat conduction of the former,
Not necessarily efficient cooling. In particular, when a corrugated pipe is used, there is a problem that the superconducting wire and the former are contacted only at the mountain portion of the pipe, and sufficient cooling cannot be performed.

[0004]

The present invention has been made in view of the above problems, and a first feature thereof is that a strip-shaped body is spirally wound into a pipe-shaped overall shape (spiral strip). ) In the former, the material is copper. The second feature is that the former is made of aluminum spiral band,
This is because a protective layer having high thermal conductivity is provided on the contact surface with the high temperature superconducting wire.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below. FIG. 1 is a side view showing a terminal of a superconducting cable using the former of the present invention, and FIG. 2 is an end view thereof. This superconducting cable has a former 1, a superconducting conductor 2,
It comprises an electrically insulating layer 3. As the superconducting conductor 2, a superconducting wire covered with a silver sheath was spirally wound around the outer periphery of the former 1. Here, the former 1 is formed in a pipe shape by spirally winding a band-shaped body. In this example, the strip was wound with a gap 4 between adjacent windings. When a refrigerant (liquid nitrogen or the like) is circulated inside the spiral band, the refrigerant flows out from this gap in the outer peripheral direction to directly cool the superconducting conductor 2. The thickness and the length of the strip may be appropriately selected in consideration of the mechanical strength of the former 1 and the required length.

As described above, by forming the former 1 in the spiral band, the cable can have flexibility like the corrugated pipe. Further, since the refrigerant flows out from the gap 4 of the spiral band toward the outer circumference of the cable, the superconducting conductor can be directly cooled. Furthermore, the former 1
By using copper as the material, there is an effect that it can be used as a current bypass and that electrolytic corrosion with the superconducting conductor can be suppressed. Since copper is a good conductor, even if the superconducting conductor changes to normal conduction (quenching), it functions as a current bypass, and the temperature rise of the conductor can be suppressed. Liquid nitrogen is generally an electrical insulator and does not cause electrolytic corrosion problems between the metals in contact with it. However, a considerable period of time may elapse after the cable is manufactured and before it is laid, cooled, and impregnated with liquid nitrogen, and moisture may penetrate between the metals. Generally, silver is used for the sheath of the superconducting conductor, and if the former is copper, the difference in electronegativity between the two metals is small and corrosion can be suppressed as much as possible.

It should be noted that it is not necessary to intentionally open a gap between adjacent turns of the spiral band. This is because even if the strip-shaped body is wound so that adjacent windings come into contact with each other, a gap in which the refrigerant flows in the outer peripheral direction of the cable is inevitably formed.

Next, the aluminum former will be described (not shown). This is also formed in a spiral band like the copper former. The difference is that the former is provided with a protective layer. The protective layer may be formed at least at a portion in contact with the superconducting conductor. Similar to copper, aluminum also functions as a current bypass when a quench occurs with a good conductor. However, there is a large difference in electronegativity from silver, which is the sheath material of the superconducting conductor, and it is considered that aluminum corrodes. For this reason, a protective layer is provided at a portion of the former that comes into contact with the superconducting conductor to prevent direct contact between aluminum and copper. As the protective layer, one having good thermal conductivity is selected. For example, Apiezon grease can be used.

[0009]

As described above, by forming the former in the spiral band, the superconducting conductor can be directly cooled by the refrigerant, and the cable can be made flexible. Therefore, the temperature rise of the conductor can be suppressed even when an insulator having a poor thermal conductivity is provided on the outer periphery of the conductor and cooling from the outer periphery of the conductor cannot be expected, or when a large current passes due to a short circuit accident or the like. Also, by using copper or aluminum for the former, the former can function as a current bypass at the time of quenching. In particular, when copper is used, the problem of electrolytic corrosion with silver used for the sheath material of the superconducting conductor can be solved. Further, even when the former is made of aluminum and the protective layer is provided, the problem of electrolytic corrosion can be similarly solved.

[Brief description of the drawings]

FIG. 1 is a side view showing a terminal of a superconducting cable using a former of the present invention.

FIG. 2 is an end view showing a terminal of a superconducting cable using the former of the present invention.

[Explanation of symbols]

 1 former 2 superconducting conductor 3 electrical insulating layer 4 gap

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hideo Ishii, 4-1, Egasaki-cho, Tsurumi-ku, Yokohama-shi, Kanagawa, Tokyo Electric Power Technology Laboratory (72) Inventor Shoichi Honjo 4 Egasaki-cho, Tsurumi-ku, Yokohama-shi, Kanagawa No. 1 Inside the Electric Power Technology Laboratory, Tokyo Electric Power Company

Claims (2)

[Claims] 1. A former for a high-temperature superconducting wire, wherein the former is a spiral band made of copper. 2. A former in which a high-temperature superconducting wire is packaged, wherein the former is a spiral band made of aluminum and has a high thermal conductive protective layer on a contact surface with the high-temperature superconducting wire. For former.