JPH1166980A - Oxide superconducting cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the capacity of an oxide superconducting cable by equalizing a current passing through respective superconductors and an effect of a self-magnetic field, restraining eddy current and increasing critical current density. SOLUTION: This oxide superconducting cable 10 is formed by insulating the element wires of a superconductor 20 formed by covering an oxide superconducting core with a sheath, and disposing a plurality of superconductors around a pipe-shaped former 40. Superconducting strand 30 with roughly retangular cross section consisting of a plurality of superconductor 20 with roughly rectangular cross section is formed into a block shape, and is wound around the former 40, thereby forming a superconducting strand layer 11. The respective superconductors 20 are stranded so as to be positioned on the front layer side and back layer side of the superconducting strand layer 11 alternately in order to equalize the effect of self-magnetic field.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oxide superconductor and an oxide superconducting cable which are being developed for use in power transmission, superconducting magnets, current leads, generators, medical equipment and the like.

[0002]

2. Description of the Related Art As an example of an oxide superconducting cable, a superconducting cable 3 in which a superconducting conductor 1 is spirally wound around a pipe 2 made of copper or the like as shown in FIG. The superconducting conductor 1 is formed by covering an oxide superconducting core 4 with a sheath 5 made of silver or the like, and winding the superconducting conductor 1 around the pipe 2 by a plurality of layers. In such a superconducting cable 3, as shown in FIG. 4, the first layer 6 of the superconducting conductor 1 wound on the surface of the pipe 2 is wound in the direction of so-called S (from the right), SZ wound in the opposite direction for each layer, such that the second layer 7 of the superconducting conductor 1 wound on the first layer 6 is wound in a direction from the so-called Z (from the left). The superconducting conductor stack 8 in a plurality of stacked states is utilized by using spiral winding in the direction of S, or spiral winding in the S-S direction, which is wound in a direction overlapping S.
Was formed.

[0003]

However, as described above, in the case of an oxide superconducting cable having a layered structure in which the superconducting conductor is wound in each layer, the cable superconducting cable is affected by the self-magnetic field of the oxide superconducting cable. A large amount of current flows through the superconducting conductor in the outer layer, and an interlayer current gradient in which the actual current decreases toward the inner layer cannot be avoided, and there is a problem that the critical current density tends to decrease. Therefore, in many cases, the above-mentioned problem has been solved by separately supplying a current to the superconducting conductor of each layer and interposing a resistor or a capacitor, a coil, or the like between the layers so that the current between the layers can be balanced. In these methods, there is a problem that the superconductivity characteristic of substantially zero resistance cannot be fully utilized.

[0004] The present invention has been made in view of the above circumstances, and aims to achieve the following objects. To equalize the value of the current flowing in each superconducting conductor and the effect of the self-magnetic field, and eliminate the interlayer current gradient of the superconducting conductor. To increase the capacity of the oxide superconducting cable by increasing the critical current density and reducing the eddy current loss generated when AC is applied. To provide an oxide superconducting cable having a simple structure. Reduce manufacturing costs.

[0005]

Means for Solving the Problems An oxide superconducting core is sealed.
Insulate the superconducting conductor formed by covering
Are placed around the pipe-shaped former,
An electrically conductive cable, comprising a superconducting conductor comprising the superconducting conductor.
The superconducting stranded wire layer is formed by the stranded wire being wound around the former.
Formed so that each superconducting conductor equalizes the effect of its own magnetic field.
In order to alternate between the surface side and the inner layer side of the superconducting stranded wire layer
Twisted to be located. Superconducting stranded wire has a roughly rectangular cross section
A superconducting conductor with a rectangular cross section
The superconducting stranded wire is formed in a
And wound in the radial direction. Where they are twisted
It is preferable that the number of superconducting conductors
Preferably, the number is nine. The core of the superconducting conductor is Bi_TwoS
r_TwoCa₁Cu_TwoO_x(Bi2212 phase), Bi_TwoSr _TwoCa
_TwoCu_ThreeO_y(Bi2223 phase), Bi_1.6Pb_0.4Sr_TwoC
a_TwoCu_ThreeO_x, Tl _TwoBa_TwoCa_TwoCu_ThreeO_y, Etc.
In particular, Bi-based 2223 phase
Or Bi-based 2212 phase Bi-based oxide superconducting material selected
Is preferably performed. The sheath is made of Ag, Pt, Au, etc.
Preferably, it is a noble metal. Twist of superconducting conductor
Is preferably 400 to 1000 times the wire diameter of the superconducting conductor.
More preferably, it is set to 400 times. Super electric
The secondary pitch at which the stranded conductor is wound around the former is
It is preferably 500 to 5000 times the wire diameter of the conductor, more preferably
More preferably, it is set to 1000 times. Inside the former
Is a flow path for a cooling medium such as liquid nitrogen,
Cooling takes place.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of an oxide superconducting cable according to the present invention will be described below with reference to the drawings. 1 to 3, reference numeral 10 denotes an oxide superconducting cable, 20 denotes a superconducting conductor, 30 denotes a superconducting stranded wire, and 40 denotes a former.

As shown in FIG. 1, an oxide superconducting cable 10 is provided with a plurality of superconducting conductors 20 whose surfaces are insulated around a pipe-shaped former 40 and a cylindrical superconducting twisted wire layer 11, for example. It is formed. The superconducting stranded wire layer 11
The superconducting conductor 20 is formed in a substantially rectangular block shape by a twisted superconducting stranded wire 30 having a substantially rectangular cross section, and the superconducting stranded wire 30 is wound around the former 40 with its width direction directed in the radial direction of the former 40. It is formed by doing.
Outside the oxide superconducting cable 10, a semiconductor layer, an insulating layer, and / or a sealing layer (not shown) are formed.

The superconducting conductor 20 has a width of about 0.5 to 2 mm and a thickness of about 0.05 to 0.7 mm. For example, the superconducting conductor 20 has a width of 1 mm and a thickness of 0.7 mm.
As shown in FIG. 3, the oxide superconducting core 21 is formed by covering it with a sheath 22 and has a thickness of, for example, 1 μm to 20 μm.
It is covered with an insulating layer 23 composed of a certain amount of enamel layer.
The oxide superconducting core 21 is made of Bi ₂ Sr ₂ Ca ₁ Cu ₂ O
_x (Bi-based 2212 phase), Bi ₂ Sr ₂ Ca ₂ Cu ₃ O
_y (Bi 2223 phase), Bi _1.6 Pb _0.4 Sr ₂ Ca ₂ C
It has a composition represented by u ₃ O _x , Tl ₂ Ba ₂ Ca ₂ Cu ₃ O _y , and the like. For example, it is formed of a Bi-based 2223 phase or a Bi-based 2212 phase among Bi-based oxide superconducting materials. You. The sheath 22 is made of a noble metal such as Ag, Pt, or Au or an alloy thereof, for example, a silver sheath.

As shown in FIGS. 1 to 3, the superconducting stranded wire 30 is formed into a substantially rectangular cross section by twisting, for example, nine superconducting conductors 20 so as to have a thickness of the superconducting stranded wire layer 11. . At this time, the twist pitch of the superconducting conductor 20 is 400 to 1000 times the wire diameter (width) of the superconducting conductor 20,
Preferably, it is set to about 400 times, for example, 0.4 m
It is said. As shown in FIG. 1, the superconducting stranded wire 30 has a long side direction (width direction) in a substantially rectangular cross section directed in a radial direction of the former 40 and a short side direction (thickness direction) in the cross section. The former 40 is wound around the former 40 in the circumferential direction. At this time, for example, 70 superconducting stranded wires 30 are spirally wound around the former 40, and at this time, the secondary pitch when the superconducting stranded wire 30 is wound around the former 40 depends on the superconducting conductor. 500 times to 5000 times, preferably 1000 times, the wire diameter (width) of 20
It is set to about twice, for example, 1 m.

The former 40 is formed in a pipe shape as shown in FIG. 1 and has, for example, an inner diameter of 32 mm and an outer diameter of 35 m. The inside of the former 40 is used as a flow path for a cooling medium such as liquid nitrogen, for example, to cool the superconductor 20.

With the above configuration, the superconducting conductors 20 are twisted to form a superconducting stranded wire 30, and the superconducting stranded wire 30 is wound around the former 40. For each twist pitch, the radial position of the superconducting stranded wire layer 11 extends in the axial direction of the oxide superconducting cable 10 while repeatedly passing from the innermost position to the outermost position. Therefore, when a current flows through the oxide superconducting cable 10, a self-magnetic field having a different strength in the radial direction of the oxide superconducting cable 10 is generated, but one superconducting conductor 20 is affected by the self-magnetic field. Is changed corresponding to the radial position change of the oxide superconducting cable 10 at each twist pitch, and is offset for each superconducting stranded wire 30. Therefore, in each superconducting conductor 20, the influence of the self-magnetic field in the axial direction of the oxide superconducting cable 10 is equalized. As a result, a current of the same value can flow through each superconducting conductor 20, and the current gradient in the radial direction of superconducting stranded layer 11 is eliminated.

Further, as shown by BB in FIG. 3, the magnetic field generated around each superconducting stranded wire 30 cancels out for each adjacent superconducting stranded wire 30. As a result, the vortex generated in the alternating current electromagnetic field. Current loss can be reduced.

[Embodiment] Bi-based Bi consisting of 2223 phases
A superconducting conductor 9 having a width of 1 mm and a thickness of 0.7 mm, comprising an oxide superconducting material as an oxide superconducting core, 19 cores of the oxide superconducting core, Ag as a sheath wire, and an enamel having a thickness of 10 μm as an insulating layer. According to the book, the twist pitch is set to 0.
A superconducting stranded wire was formed to have a length of 4 m, and 70 superconducting stranded wires were wound around a stainless steel former having an outer diameter of 35 mm and an inner diameter of 32 mm at a secondary pitch of 1 m to prepare an oxide superconducting cable. A measurement experiment was performed on the oxide superconducting cable under the following conditions. External magnetic field: 0T Temperature: 77K Critical current value of one superconducting conductor: 5A Critical current value of one superconducting stranded wire: 45A Critical current value of oxide superconducting cable: 3150A Current value of one superconducting conductor: 4 0.5A Current value of one superconducting twisted wire: 40.5A Current value of oxide superconducting cable: 2835A As a result, it was measured that a current of about 90% of the critical current value flows through each superconducting conductor.

Further, in the above-described oxide superconducting cable, a cable in which the twist pitch of the superconducting conductor was changed was prepared, and a measurement experiment was performed. Table 1 shows the results.

[0015]

[Table 1]

As a result, the twist pitch L of the superconducting conductor becomes
It has been measured that the current value flowing can be improved by setting the wire diameter (width) of the superconducting conductor to 400 to 4000 times, preferably about 400 times.

[0017]

According to the oxide superconducting cable of the present invention, the following effects can be obtained. (1) The superconducting stranded wire is formed by the superconducting conductor, and the width direction of the superconducting stranded wire is directed in the radial direction of the oxide superconducting cable, so that the superconducting conductor alternates between the innermost and outermost layers of the superconducting stranded wire layer. , It is possible to equalize the value of the current flowing through each superconducting conductor and the effect of the self-magnetic field. (2) Since the current flowing in each superconducting conductor and the influence of the self-magnetic field are equal, the current gradient in the superconducting twisted wire layer is eliminated, and the current flows through the superconducting conductor located inside and the critical current density increases. In addition, the eddy current loss generated when AC current is applied can be reduced, and the capacity of the oxide superconducting cable can be increased. (3) Since it is not necessary to equalize the current gradient generated in each layer of the superconducting conductor by a capacitor, a resistor, or the like, the value of the current flowing through each superconducting conductor and the effect of the self-magnetic field are equalized, and Further, it is possible to provide an oxide superconducting cable having a simple structure, while maintaining a large capacity of the oxide superconducting cable by eliminating a current gradient in the superconducting stranded wire layer. (4) The manufacturing cost can be reduced by the above.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of an oxide superconducting cable according to the present invention.

FIG. 2 is an enlarged perspective view showing a superconducting stranded wire in the oxide superconducting cable of FIG.

FIG. 3 is a schematic sectional view showing a reduction in eddy current loss in the superconducting stranded wire layer of FIG.

FIG. 4 is a perspective view showing a conventional oxide superconducting cable.

[Explanation of symbols]

10: oxide superconducting cable, 11: superconducting stranded wire layer, 2
0: superconducting conductor, 21: oxide superconducting core, 22: sheath, 23: insulating layer, 30: superconducting stranded wire, 40: former

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Nobuyuki Sadakata 1-5-1 Kiba, Koto-ku, Tokyo Inside Fujikura Co., Ltd. (72) Inventor Takashi Saito 1-1-5-1 Kiba, Koto-ku, Tokyo Stock Inside Fujikura Corporation (72) Inventor Tatsuya Suematsu 42-1 Shintomi, Futtsu City, Chiba Prefecture Inside Fujikura Futtsu Plant (72) Inventor Shigeo Nagaya 20-1, Kitakanyama, Odaka-cho, Midori-ku, Nagoya City, Aichi Prefecture Chubu Electric Power Co., Ltd.

Claims (3)

[Claims] A superconducting conductor formed by covering an oxide superconducting core with a sheath is insulated by wires, and the superconducting conductor is a plurality of oxide superconducting cables arranged around a pipe-shaped former, wherein the superconducting conductor is provided. A superconducting stranded wire having a substantially rectangular cross section is wound around a former to form a superconducting stranded wire layer. An oxide superconducting cable characterized in that the cable is twisted so as to be alternately positioned on the side. 2. The oxide superconducting cable according to claim 1, wherein the width direction of the superconducting stranded wire is oriented in the radial direction of the former. 3. The oxide superconducting cable according to claim 1, wherein the twist pitch of the superconducting conductor is set to 400 to 1000 times the wire diameter of the superconducting conductor.