JP2013140691A - Structure of interconnecting superconducting cable, and method of connecting superconducting cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low loss structure of interconnecting superconducting cables, and a method of connecting superconducting cables for use in configuring the interconnection structure.SOLUTION: A structure 1 of interconnecting superconducting cables comprises: a connecting sleeve 2 interconnecting formers 110A and 110B and having about the same outside diameter as the formers; connection part wire rod layers 31, 32, ... including a plurality of parallel connecting superconducting wire rods 3 and interconnecting superconducting wire rods constituting cable wire rod layers 121A and 121B (122A, 122B, ...) constituting superconductors; and connection part insulating layers 41, 42, ... arranged so as to bridge interlayer insulating layers 131A, 131B, ... and interposed between the connection part wire rod layers 31, 32, .... With the connection insulating layers 41, 42, ..., the interconnection structure 1 can reduce a loss due to a skin effect. Helical winding of the connecting superconducting wire rods 3 can reduce a connection resistance, so that the interconnection structure 1 also implements a low loss in this regard.

Description

  The present invention relates to a superconducting cable intermediate connection structure for connecting superconducting cables having superconducting conductors on the outer periphery of a former, and a superconducting cable connection method for constructing a connecting structure for connecting the superconducting cables. In particular, the present invention relates to an intermediate connection structure of a low-loss superconducting cable.

  Superconducting cables are being developed as power cables constituting power supply paths. A superconducting cable typically includes a cable core having a former, a superconducting conductor, and an electrically insulating layer in order from the inside, and a heat insulating tube that houses the cable core and is filled with a refrigerant such as liquid nitrogen. The superconducting conductor is typically constituted by spirally winding a superconducting wire, and by laminating this winding layer (hereinafter referred to as a cable wire layer) in multiple layers (such as FIG. 2 of Patent Document 1). Can be a large capacity cable.

  When constructing a superconducting cable line over a long distance, an intermediate connection for connecting different superconducting cables is required in the middle of the line. Patent Document 1 discloses that a plurality of cable wire layers laminated in multiple layers constituting a superconducting conductor are connected by a plurality of superconducting wires vertically connected (superconducting wire for connection), and laminated cable wire layers. A structure in which the connection superconducting wires stacked in the same manner as above are integrated with solder or the like (hereinafter referred to as a multilayer integrated structure) is disclosed. In constructing this multi-layered integrated structure, Patent Document 1 describes that a plurality of laminated bodies in which a plurality of connecting superconducting wires having different lengths are laminated and integrated with solder or the like are prepared, and the plurality of laminated bodies are arranged in parallel. It is proposed to use a fixed interdigital connecting member.

  By using the connection member having the multilayer structure described above, the construction time of the intermediate connection structure can be shortened and the workability is excellent. In addition, since the connection member of this multilayer structure is integrated with solder as described above and has excellent strength, when forming a reinforcing insulating layer on the outer periphery of the connection member, an insulating paper tape or the like can be wound. Even if the generated torque is loaded, the connecting superconducting wire can be prevented from buckling or being damaged.

JP 2008-245477

  Reduction of the loss in the location which connects superconducting cables is desired.

  When the power supply path having the above-mentioned multilayer integrated structure is used for AC power transmission, a skin effect in which current concentrates on the wires arranged on the outer peripheral side among the laminated superconducting wires for connection occurs, and AC loss increases. To do. In particular, when the connecting superconducting wire is a thin film wire having a superconducting thin film on a metal substrate, the AC loss due to the skin effect tends to be larger than that of a wire having a superconducting phase covered with a metal matrix.

  In addition, since the entire laminated superconducting wire for connection cannot be fully utilized, current is shunted to a place other than the superconducting phase (for example, when the connecting superconducting wire is the above-described thin film wire, a metal substrate, etc.). There is a risk that energization loss will increase.

  Accordingly, one object of the present invention is to provide an intermediate connection structure for a superconducting cable with low loss. Another object of the present invention is to provide a superconducting cable connection method capable of constructing a low-loss intermediate connection structure.

  When the outer diameter of the connection sleeve is large, for example, when a connection sleeve having an outer diameter larger than the outer diameter of the outermost cable wire layer constituting the superconducting conductor is provided, electric field stress is generated in the stacking direction of the superconducting wire. . In Patent Document 1, a connection sleeve having a relatively large outer diameter is used, but by forming a reinforcing insulating layer including a stress cone on the outer periphery of the connection superconducting wire integrated in the above-described multilayer, Electric field stress can be reduced. However, since the reinforcing insulating layer having a large stress cone becomes large in the radial direction and the longitudinal direction, the torque due to the winding of the insulating paper tape becomes large. In order to prevent buckling of the connecting superconducting wire due to this torque, the multilayer integrated structure described above is adopted.

  Therefore, the present invention achieves the above object by using a connection sleeve having a small outer diameter and providing an insulating layer between layers of a superconducting wire for connection that bridges between cable wire layers.

  The superconducting cable intermediate connection structure of the present invention includes a superconducting conductor in which a cable wire layer formed by spirally winding a superconducting wire around the former is laminated in multiple layers, and an interlayer insulating layer interposed between the cable wire layers. To connect the superconducting cables. This intermediate connection structure is composed of a conductive material, and is composed of a connection sleeve for connecting the formers included in each superconducting cable, and a plurality of superconducting wires for connection arranged in parallel, and the cable included in each superconducting cable. A connection portion wire layer that connects the superconducting wires constituting the wire layer and a connection portion insulation layer that is made of an insulating material are provided. The connection sleeve has an outer diameter equal to or greater than the outer diameter of the former and equal to or smaller than the outer diameter of the cable wire layer located on the outermost side of the superconducting conductor. Further, this intermediate connection structure includes a plurality of connection portion wire layers, and these connection portion wire layers are laminated, and the connection portion insulation layers are arranged so as to cross the interlayer insulation layers provided in each superconducting cable. In addition, it is interposed between the connection part wire layers stacked in multiple layers.

  Since the connection sleeve has the above specific size, the reinforcing insulating layer provided on the outer periphery of the connection superconducting wire provided between the cable wire layers included in the superconducting cable can have a small stress cone. That is, the outer diameter of the reinforcing insulating layer can be reduced, the torque due to the winding of the insulating paper tape constituting the reinforcing insulating layer is small, and the connecting superconducting wire is not easily buckled by the torque. Therefore, it is not necessary to integrate the laminated superconducting wires for connection, and a connection insulating layer can be provided. Moreover, since the said torque is small, the insulating paper which comprises a connection part insulating layer cannot shift | deviate easily, and can insulate a connection part wire material layer favorably.

  The intermediate connection structure of the present invention includes a connection part insulating layer that electrically insulates the stacked connection part wire layers, so that a current can flow uniformly through each connection part wire layer. Therefore, even when the power supply path having the intermediate connection structure of the present invention is used for AC power transmission, AC loss due to the skin effect can be reduced. Further, by reducing the diameter of the connection sleeve, the outer diameter of the reinforcing insulating layer can be reduced as described above, and the intermediate connection structure of the present invention is small.

  As one form of this invention, the form by which each superconducting wire for connection which comprises the said connection part wire layer was helically wound with the helical pitch similar to the helical pitch of the superconducting wire which comprises the said cable wire layer is mentioned. .

  In the above-described form, the superconducting wires wound at a predetermined helical pitch, which are constituent elements such as a superconducting conductor included in the superconducting cable, are connected by connecting superconducting wires arranged at a similar helical pitch, Connection resistance between wires can be reduced. Therefore, the said form can anticipate reduction of the loss by reduction of connection resistance.

  As one form of this invention, the form whose said superconducting wire and said connection superconducting wire are thin film wires which provide a superconducting thin film on a metal base material is mentioned. In this embodiment, the superconducting wire is disposed with the superconducting thin film facing the outer peripheral side, the connecting superconducting wire is disposed with the superconducting thin film facing the inner peripheral side, and the two superconducting thin films are bonded together facing each other. It is preferable.

  In the above configuration, although the cable wire layer and the connection portion wire layer are constituted by the thin film wire that tends to have a large AC loss due to the skin effect, the loss can be reduced by providing the connection portion insulating layer as described above. . In addition, the thin film wire has a higher critical current density at the liquid nitrogen temperature than the wire in which the superconducting phase is covered with a metal matrix, and the above form is expected to be particularly preferable for high current applications. Especially, the form joined as the above-mentioned superconducting thin films face each other can reduce the connection resistance between the wires, and can be expected to reduce the loss due to the reduction of the connection resistance.

  As one aspect of the present invention, the connection part insulating layer is formed by winding at least one kind of insulating paper of wide insulating paper, narrow insulating paper, and crepe insulating paper, and the insulating paper is made of a bonding material. The form fixed to the said interlayer insulation layer is mentioned. The wide insulating paper has a length of one side arranged substantially along the axial direction of the superconducting cable equal to or longer than the length between the interlayer insulating layers provided in each superconducting cable, and the narrow insulating paper is It has a width equal to or greater than the width of the insulating paper constituting the interlayer insulating layer and equal to or smaller than the length of the one side of the wide insulating paper. In this embodiment, it is preferable that the insulating paper is spirally wound at a helical pitch similar to that of the insulating paper constituting the interlayer insulating layer. The length between the interlayer insulating layers is the distance between the end surfaces of the interlayer insulating layers included in each superconducting cable (the length along the axial direction of the superconducting cable).

  The connection part insulating layer is made of insulating paper, thereby satisfying desired insulation characteristics and sufficiently immersing a coolant such as liquid nitrogen to cool the connection superconducting wire and maintain the superconducting state. .

  In particular, the configuration in which the connecting portion insulating layer is configured by the specific wide insulating paper is such that the connecting portion wire layer is not easily exposed even when the insulating paper is displaced, and the connecting superconducting wires stacked at the exposed portion are connected to each other. Can be avoided, and the connection portion wire layer can be well insulated. Further, when the specific wide insulating paper is used, the connection portion insulating layer can be formed with a small number of windings, and the formation time can be shortened and the workability is excellent.

  In particular, the configuration in which the connection portion insulating layer is formed of the specific narrow width insulating paper can have, for example, a uniform specification of the connection portion insulating layer and the interlayer insulating layer included in the superconducting cable. The connection location can be treated as uniform. In addition, by setting the connection portion insulating layer to the same specifications as the interlayer insulating layer, it is easy to adjust the winding conditions and the like in forming the connection portion insulating layer, and the workability is excellent.

  In particular, the form in which the connecting portion insulating layer is configured by the crepe insulating paper makes use of the cushioning property to cause the connecting portion insulating layer to function as a protective layer of the connecting superconducting wire, to absorb dimensional errors, etc. can do.

  In any of the above-described insulating papers, in the form wound at a spiral pitch similar to the spiral pitch of the insulating paper constituting the interlayer insulating layer included in the superconducting cable, the winding of the insulating paper constituting the connecting portion insulating layer is used. The torque due to the rotation can be made about the same as that of the superconducting cable (the degree that the superconducting wire is not buckled). Therefore, the buckling of the connecting superconducting wire due to the torque can be prevented.

The intermediate connection structure of the present invention can be constructed, for example, by using the following connection method of the present invention. The superconducting cable connection method of the present invention comprises a superconducting conductor in which a cable wire layer formed by spirally winding a superconducting wire around the former is laminated in multiple layers, and an interlayer insulating layer interposed between the cable wire layers. The present invention relates to a method for connecting superconducting cables, and includes the following steps.
A step of stripping the connection end of each superconducting cable to expose the former, the cable wire layer, and the interlayer insulating layer in a stepped manner.
The former included in each superconducting cable is inserted into a connecting sleeve made of a conductive material, and the outer diameter of the connecting sleeve is equal to or larger than the outer diameter of the former, and the cable wire layer layer located on the outermost side of the superconducting conductor A step of compressing the connection sleeve so as to be equal to or less than the outer diameter and connecting the formers.
A connecting member formed by temporarily fixing a plurality of connecting superconducting wires arranged in parallel in a comb shape is wound around the outer periphery of the connecting sleeve, and the connecting superconducting wires are provided between the cable wire layers provided in each superconducting cable, The process of joining the said cable wire material layers by joining the superconducting wire which comprises the said cable wire material layer, and the said superconducting wire for a connection.
A step of disposing an insulating material on an outer periphery of the connecting superconducting wire to form a connecting portion insulating layer across the interlayer insulating layers provided in each superconducting cable;

  In the connection method of the present invention, by using the above-described connection member, a plurality of connection superconducting wires can be easily and simultaneously disposed on the outer periphery of the connection sleeve, and the workability is excellent. In the connection method of the present invention, a small intermediate connection structure can be constructed by compressing the connection sleeve to a specific size. A plurality of connection members as described above are prepared, and a multi-layer structure corresponding to the number of cable wire layers and the number of interlayer insulation layers is obtained by repeatedly constructing the connection portion wire layers and the connection portion insulation layers using the prepared connection members. The intermediate connection structure of the present invention having a low loss can be formed by including the connection portion wire layer and at least one connection portion insulating layer.

  The connecting member can be formed as follows, for example. Using a cut piece of the superconducting wire cut from the superconducting cable by stripping, a paper pattern having a spiral pitch similar to that of the superconducting wire is produced. Next, the superconducting wire prepared separately is cut along the pattern, and the superconducting wire for connection is produced. And the produced some said superconducting wire for a connection is arranged in parallel along the said pattern, and is integrated with a temporary fixing material.

  A superconducting wire for connection having the same helical pitch as that of the superconducting wire is produced by making a pattern using a cut piece formed by cutting the superconducting wire constituting the superconducting conductor included in the superconducting cable. Can be prepared easily and accurately. Further, by arranging the connecting superconducting wires prepared along the pattern, a plurality of connecting superconducting wires having a predetermined helical pitch can be easily and accurately arranged in parallel. Furthermore, by temporarily fixing, it is possible to easily maintain a state in which a plurality of superconducting wires for connection having the helical pitch are arranged. And the intermediate connection structure where the helical pitch of the superconducting wire which comprises the cable wire layer mentioned above and the helical pitch of the superconducting wire for connection which comprises the connection part wire layer are equal by using the obtained interdigital connecting member Can be built easily.

  The intermediate connection structure of the superconducting cable of the present invention has low loss. The superconducting cable connection method of the present invention can construct a low-loss intermediate connection structure.

FIG. 3 is a longitudinal sectional view showing a main part in the intermediate connection structure for a superconducting cable according to the first embodiment. FIG. 3 is a plan view showing an outline of a connection member used for constructing the intermediate connection structure of the superconducting cable of the first embodiment. It is a process explanatory view showing the construction procedure of the intermediate connection structure of the superconducting cable of Embodiment 1, (A) is a state in which a plurality of superconducting wires for connection are arranged, (B) is a connection part insulating layer on the outer periphery thereof The state which has comprised the insulating paper which comprises is shown. It is a schematic perspective view which shows the cut model of a 3 core lump superconducting cable.

  Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, only the upper half is shown from the center line of the intermediate connection structure, and the lower half is omitted. Moreover, the same code | symbol shows the same name thing in the following drawings.

(Embodiment 1)
The superconducting cable intermediate connection structure 1 of Embodiment 1 is provided at a location where a superconducting conductor is formed of a multi-layered cable wire layer and a pair of superconducting cables in which an interlayer insulating layer is interposed between the cable wire layers is connected. Yes, the cable wire layers are connected by the superconducting wire 3 for connection. The intermediate connection structure 1 includes a plurality of connection portion wire layers 31, 32,... Composed of connection superconducting wires 3, and is interposed between the connection portion wire layers 31, 32 arranged in multiple layers. The most characteristic feature is that it includes partial insulating layers 41, 42. First, a superconducting cable will be described with reference to FIG.

[Superconducting cable]
The superconducting cable 1000 includes a cable core 100 including a superconducting conductor 120, and a heat insulating tube 200 that houses the cable core 100 and is filled with a refrigerant such as liquid nitrogen. The superconducting cable 1000 shown in FIG. 4 shows a multi-core cable (in this case, a 3-core collective cable) in which a plurality of cable cores 100 are housed in one heat insulation tube 200, but one cable core is housed in one heat insulation tube. It can be a single core cable.

  The cable core 100 includes a former 110, a superconducting conductor 120, an interlayer insulating layer 130, an electric insulating layer 140, a superconducting shield layer 150, a normal conducting layer 160, and a protective layer 170 in order from the center.

  The former 110 is used for supporting the superconducting conductor 120, the tensile strength material of the cable 1000, and other current paths for diverting an accident current in case of an accident such as a short circuit or a ground fault. For this purpose, the former 110 can be a solid body or hollow body (tubular body) made of a normal conducting material such as copper or aluminum. Examples of the solid body include a stranded wire obtained by twisting a plurality of copper wires each having an insulation coating such as polyvinyl formal (PVF) or enamel. Here, the former 110 is made of a stranded wire, and can be easily compressed by the connecting sleeve 2 described later.

  On the outer periphery of the former 110, at least one of insulating paper such as kraft paper or insulating material such as semi-synthetic insulating paper in which kraft paper and plastic are combined, crepe carbon paper, metal carbon paper, and metalized paper A cushion layer 112 formed by winding a conductive tape made of a conductive material can be provided. When a conductive material is used, the cushion layer 112 can function as a semiconductive layer. Here, the cushion layer 112 is made of crepe carbon paper, metal carbon paper, and metallized paper.

  Each of the superconducting conductor 120 and the superconducting shield layer 150 includes a single layer or a multilayer including a cable wire layer in which a superconducting wire is spirally wound. In the present invention, at least the superconducting conductor 120 includes a plurality of cable wire layers. Here, the superconducting conductor 120 includes four cable wire layers 121 to 124, and the superconducting shield layer 150 includes two cable wire layers, both of which have a multilayer structure. The number of cable wire layers constituting the superconducting conductor 120 can be appropriately selected according to the capacity of the cable, and the larger the number of layers, the larger the capacity of power transmission. The superconducting shield layer 150 functions as a magnetic shielding layer by flowing a current in a direction opposite to that of the superconducting conductor 120 due to electromagnetic induction from the superconducting conductor 120 in an AC power transmission application, and is used as a return conductor in a DC power transmission application, for example. (The superconducting conductor 120 is the forward path). Therefore, the number of the cable wire layers constituting the superconducting shield layer 150 may be selected according to the capacity of the superconducting conductor 120. The size (width, thickness) and number of superconducting wires constituting one cable wire layer can be appropriately selected according to the desired capacity.

Examples of the superconducting wire include a wire having an oxide superconducting phase. Specifically, when RE is a rare earth element, it is called RE2 wire with a rare earth oxide superconducting phase such as REBa ₂ Cu ₃ O _x (for example, YBCO, HoBCO, GdBCO, etc.) called RE123, or Bi2223. A high-temperature superconducting wire such as a Bi-based wire including a Bi-based oxide superconducting phase such as Bi ₂ Sr ₂ Ca ₂ Cu ₃ O _{10 + δ} and Ag or an Ag alloy as a metal matrix can be mentioned. The RE-based wire includes a superconducting thin film made of the above-described oxide superconducting phase containing a rare earth element on a metal substrate made of a metal such as nickel, copper, silver, and alloys thereof, and is generally called a thin film wire. The thin film wire typically has a multilayer film structure including the above-described metal substrate, intermediate layer, superconducting thin film, and stabilizing layer in this order. RE-based wire has a higher critical current density than Bi-based wire, and can construct a thin superconducting wire.

  Here, both the superconducting conductor 120 and the superconducting shield layer 150 are made of a thin film wire. More specifically, the superconducting conductor 120 is on the former 110, the superconducting shield layer 150 is on the electrical insulating layer 140 described later, and the above-described superconducting thin film is on the outer peripheral side and the metal substrate is on the inner peripheral side. As described above, the thin film wire is wound at a predetermined spiral pitch.

  Interlayer insulating layers 131, 132, 133 are provided between the cable wire layers 121, 122, 122, 123, 123, 124 constituting the superconducting conductor 120. Each of the interlayer insulating layers 131 to 133 is configured by winding insulating paper such as kraft paper or semi-synthetic insulating paper at a predetermined spiral pitch. By providing the interlayer insulation layers 131 to 133, the superconducting cable 1000 can flow a current uniformly to each of the cable wire layers 121 to 124 constituting the superconducting conductor 120 when used for AC power transmission. Loss can be reduced. It is preferable to provide an interlayer insulating layer also between the cable wire layers constituting the superconducting shield layer 150.

  In addition, a semiconductive layer can be provided immediately above the superconducting conductor 120 by appropriately winding carbon paper or the like.

  The electrical insulating layer 140 can be configured by winding a tape made of insulating paper such as kraft paper or semi-synthetic insulating paper. Here, the electrical insulating layer 140 is configured by winding semi-synthetic insulating paper (PPLP: registered trademark manufactured by Sumitomo Electric Industries, Ltd.) at a predetermined spiral pitch.

  The normal conducting layer 160 is mainly used for a flow path of a large accident current that occurs instantaneously when quenched due to an accident or the like. Therefore, the normal conductive layer 160 can be formed of the above-described normal conductive material, similar to the former 110. More specifically, a configuration in which a copper tape is spirally wound in multiple layers is exemplified.

  The protective layer 170 is provided to mechanically protect the superconducting shield layer 150, the normal conductive layer 160, and the like. Examples of the protective layer 170 include a configuration in which semi-synthetic insulating paper such as kraft paper or PPLP (registered trademark) is wound around the outer periphery of the normal conductive layer 160.

  The heat insulating tube 200 is a double heat insulating tube 200 composed of an inner tube 201 and an outer tube 202, and typically has a vacuum heat insulating structure in which a vacuum is drawn between the inner tube 201 and the outer tube 202. During operation, the inner tube 201 is filled with a refrigerant (not shown) such as liquid nitrogen to maintain the superconducting conductor 120 and the superconducting shield layer 150 in a superconducting state. Between the inner tube 201 and the outer tube 202, a heat insulating material 203 such as a super insulation, and a spacer (not shown) for maintaining a distance between the two tubes 201 and 202 can be arranged.

  The anticorrosion layer 210 provided on the outer periphery of the outer tube 202 enhances corrosion resistance. The anticorrosion layer 210 can be formed by extruding a material having excellent corrosion resistance such as polyvinyl chloride (PVC).

[Intermediate connection structure]
The connecting ends of the cable core 100 drawn out from the ends of the pair of superconducting cables 1000 having the above-described configuration are stepped off, and the cable wire layers 121, 122, 123, and 124 constituting the former 110 and the superconducting conductor 120, the layers between the cable wire layers. The intermediate connection structure 1 is constructed where the insulating layers 131, 132, 133, the electrical insulating layer 140, the superconducting shield layer 150, and the normal conductive layer 160 are exposed in a stepped manner. Hereinafter, the configuration of the intermediate connection structure 1 will be described with reference to FIG. In FIG. 1, only the vicinity of the connection portion of the superconducting conductor is shown. Further, in FIG. 1, only two layers on the former side are shown among the cable wire layers constituting the superconducting conductor, and two layers on the outer peripheral side are omitted.

  The main part of the intermediate connection structure 1 is composed of a connection sleeve 2 that connects the formers 110A and 110B, and a superconducting wire 3 for connection that connects the cable wire layers {121A, 121B}, {122A, 122B},. Are a plurality of connecting portion wire layers 31, 32,... And a plurality of connecting portion insulating layers 41, 42,... Interposed between the connecting portion wire layers {31, 32}. Hereinafter, each configuration will be described in detail.

  The connection sleeve 2 is a cylindrical member having a through hole and is made of a normal conductive material such as copper or a copper alloy. The connection sleeve 2 is disposed on the outer periphery of both of the formers 110A and 110B provided in each cable core (hereinafter referred to as core A and core B) drawn from a pair of superconducting cables to be connected. In particular, in the present invention, the outer diameter of the connecting sleeve 2 is equal to or greater than the outer diameter of the formers 110A and 110B in the core A and the core B, and is equal to or smaller than the outer diameter of the outermost cable wire layer (here, the fourth layer). Is one of the characteristics. Here, the outer diameter of the connection sleeve 2 is substantially equal to the outer diameter of the formers 110A and 110B.

In the connecting sleeve 2, the formers 110A and 110B are inserted and disposed in the through holes, and compressed in a state of being abutted, so that the former is joined to both the formers 110A and 110B and also connects the formers 110A and 110B. The connection sleeve 2 is selected and the compression force is adjusted so that the outer diameter after compression satisfies the specific range. The smaller the outer diameter after compression, the smaller the stress cone and the smaller the outer diameter, so the outer diameter R _{f of the} former is the thickness of the superconducting conductor t _s (the difference between the outer diameter of the superconducting conductor and the outer diameter of the former. 1/2 was added magnitude _{of) (R f + (1/2)} × t s) or less, further, 1/3 was added magnitude of thickness t _s of the superconducting conductor (R _f + (1 / 3) × t _s ) or less is preferable, and it is more preferable that the outer diameter of the former is about the same as in this example. The outer diameter of the connection sleeve after compression can be less than the outer diameter of the former.

  Here, the intermediate connection structure 1 includes a connection portion cushion layer 7 on the outer periphery of the connection sleeve 2. The connecting portion cushion layer 7 covers the outer periphery of the connecting sleeve 2 and is provided so as to cross the cushion layers 112A and 112B provided on the outer periphery of the formers 110A and 110B. The connecting portion cushion layer 7 is made of crepe paper having cushioning properties, and the cushioning property can achieve mechanical protection of the connecting portion wire layers 31, 32,... And absorption of dimensional errors. In particular, the connection portion cushion layer 7 can function as a semiconductive layer when it is made of a conductive tape such as the above-mentioned crepe carbon paper. Here, the connection portion cushion layer 7 is formed by winding crepe carbon paper, metal carbon paper, and metallized paper in the same manner as the cushion layers 112A and 112B.

  The connection portion wire layers 31, 32,... Are cable wire layers 121A, 122A,... Constituting the superconducting conductor provided in the core A, and cable wire layers 121B, 122B,... Constituting the superconducting conductor provided in the core B. Connect each. Since the basic configuration of the connection portion wire layers 31, 32,... Is the same, the connection portion wire layer 31 will be described below as an example.

  As shown in FIG. 3 (A), the connecting portion wire layer 31 is composed of a plurality of connecting superconducting wires 3 connected in parallel. Each connection superconducting wire 3 is sufficiently longer than the length between the cable wire layers 121A and 121B to be connected (the distance in the left-right direction in FIG. 3A) and crosses between the cable wire layers 121A and 121B. Has been placed. One end of each connection superconducting wire 3 is joined to the superconducting wire 12A constituting the cable wire layer 121A via the wire joining layer 5 (FIG. 1), and the other end is joined to the superconducting wire 12B constituting the cable wire layer 121B. Bonded via the wire bonding layer 5.

  As the superconducting wire 3 for connection, the above-described thin film wire or Bi-based wire used for the cable wire layers 121A and 121B can be used. In addition, the connection superconducting wire 3 and the superconducting wires 12A and 12B can have different specifications (size, material such as width and thickness). For example, if the connecting superconducting wire 3 is made wider than the superconducting wires 12A and 12B, the number of joints can be reduced. On the other hand, if the superconducting wire 3 for connection and the superconducting wires 12A, 12B have the same specifications (size, material such as width and thickness), the superconducting wire 12A and the cable constituting the cable wire layer 121A by the wire 3 The superconducting wire 12B constituting the wire layer 121B can be reliably connected, and the connection resistance can be reduced. Here, the superconducting wire 3 for connection and the superconducting wires 12A and 12B have the same specifications. Therefore, the number of superconducting wires 3 for connection constituting the connecting wire layer 31 is the same as the number of superconducting wires 12A, 12B constituting the cable wire layers 121A, 121B.

  Here, the connecting superconducting wire 3 is a thin film wire similar to the superconducting wires 12A and 12B. However, in the superconducting wire 3 for connection, the superconducting thin film is arranged facing the inner peripheral side. That is, the connecting superconducting wire 3 and the superconducting wires 12A and 12B are arranged with the superconducting thin film facing each other, and are joined by the wire joining layer 5. With this configuration, the intermediate connection structure 1 can effectively reduce the connection resistance.

  Further, here, the connecting superconducting wire 3 constituting the connecting wire layer 31 is spirally wound at the same helical pitch as the superconducting wire 12A, 12B constituting the connecting cable wire layers 121A, 121B. Configured. Therefore, the superconducting wire 12A that constitutes the cable wire layer 121A, the superconducting wire 3 for connection, and the superconducting wire 12B that constitutes the cable wire layer 121B are apparently one continuous superconducting wire having no connection point. It is the state wound by the helical pitch. With this configuration, a plurality of connecting superconducting wires 3 are arranged in parallel in the axial direction of the cores A and B, and compared with a configuration in which the connecting superconducting wires 1 are arranged between the superconducting wires 12A and the superconducting wires 12B. Can further reduce the connection resistance between the wires.

  A plurality of connecting superconducting wires 3 may be arranged in parallel in the axial direction of the cores A and B as described above. In this embodiment, a connecting member can be easily produced using the connecting superconducting wire 3 cut to a predetermined length without using a pattern to be described later.

  The wire bonding layer 5 can be formed of a bonding material having conductivity such as solder. In particular, when a bonding material having a low melting point of 160 ° C. or lower (for example, In or In—Ag alloy) is used, it is difficult to deteriorate the characteristics of the wire due to heat at the time of melting.

  The connecting portion insulating layers 41, 42,... Are arranged so as to cross between the interlayer insulating layers 131A,... Provided in the core A and the interlayer insulating layers 131B provided in the core B, and are stacked. Insulating between the wire layers 31, 32, between the connecting portion wire layers 32, ..., respectively. Since the basic configuration of the connection portion insulating layers 41, 42,... Is the same, the connection portion insulating layer 41 will be described below as an example.

  The connection insulating layer 41 is configured by winding an insulating material that can be permeable to a refrigerant such as liquid nitrogen, typically, an insulating paper such as the above-mentioned kraft paper or a semi-synthetic insulating paper such as PPLP (registered trademark). . For example, the connection portion insulating layer 41 may be formed by winding a wide insulating paper (including semi-synthetic insulating paper). Specifically, the length of one side arranged substantially along the axial direction of the superconducting cables (formers 110A, 110B) is between the interlayer insulating layer 131A provided in the core A and the interlayer insulating layer 131B provided in the core B. An insulating paper having a length equal to or longer than the distance (distance between end surfaces of the interlayer insulating layers 131A and 131B) can be given. Specific values for the length of the one side include about 300 mm to 1000 mm. By using this wide insulating paper, the connection part insulating layer 41 can be formed with a small number of turns, so that the workability is excellent and a wide range can be covered at a time. It is difficult to be exposed, and it is easy to avoid contact between the connection portion wire layers 31 and 32 at the exposed portion.

  Alternatively, the connecting portion insulating layer 41 is an insulating paper having a width equal to or larger than the width of the insulating paper constituting the interlayer insulating layers 131A and 131B and not more than the length of one side of the wide insulating paper: narrow insulating paper ( (Including semi-synthetic insulating paper). A specific width is about 10 mm to 20 mm. When this narrow insulating paper is used, in forming the connection portion insulating layer 41, the winding conditions can be set to the same conditions as the interlayer insulating layer included in the cable, and the same mechanical properties as the interlayer insulating layer. The connecting portion insulating layer 41 having strength can be obtained.

  Alternatively, for example, the connection portion insulating layer 41 may be formed by winding crepe insulating paper. This form is mechanical protection of the connecting superconductor wire 3 constituting the connecting wire layer 31 located on the inner peripheral side of the connecting portion insulating layer 41 and the connecting wire material layer 32 located on the outer peripheral side, of the connecting wire layer. An effect such as absorption of dimensional errors generated during the formation can be expected.

  In addition, the connecting portion insulating layer 41 can be formed by combining the above-described wide insulating paper, narrow insulating paper, and crepe insulating paper. Further, the connection portion insulating layer 41 can be formed by an insulating material having sufficient adhesiveness in the refrigerant immersion state. In this form, (1) the insulating material can be easily fixed to the connection portion wire layer 31, (2) peeling and displacement hardly occur after formation, and (3) the connection portion wire layer 32 on the connection portion insulating layer 41. Has the advantage of being easy to form.

  The insulating paper constituting the connecting portion insulating layer 41 is preferably wound at a spiral pitch similar to the spiral pitch of the insulating paper constituting the interlayer insulating layers 131A and 131B. In this case, the torque due to the winding of the insulating paper constituting the connecting portion insulating layer 41 is approximately the same as the torque due to the winding of the insulating paper constituting the interlayer insulating layers 131A and 131B. That is, the torque in the connecting portion insulating layer 41 has such a magnitude that the superconducting wires 12A and 12B constituting the cable wire layers 121A and 121B below the interlayer insulating layers 131A and 131B are not buckled. Therefore, in this case, it is possible to prevent the connecting superconducting wire 3 from being buckled by the torque described above.

  Here, the connecting portion insulating layer 41 is made of kraft paper, and the wide insulating paper 4 having a length of about 400 mm on one side has the same spiral pitch as the spiral pitch of the insulating paper constituting the interlayer insulating layers 131A and 131B. It is wound and configured. The length of the other side of the insulating paper 4 is not less than the length in the circumferential direction of the connection portion wire layers 121A and 121B, and can be appropriately selected depending on the number of windings.

  The ends of the insulating paper 4 constituting the connection part insulating layer 41 can be fixed, for example, by being sandwiched between the insulating papers constituting the interlayer insulating layers 131A and 131B. Alternatively, if the end portion of the insulating paper 4 is fixed by a bonding material made of a material having resistance to a refrigerant such as liquid nitrogen, the connecting portion insulating layer 41 is not easily displaced, and is sufficient as an interlayer insulating layer at the connecting portion. Can function. As the bonding material, for example, a meltable adhesive tape, a tape having an adhesive layer (for example, a tape made of a fluororesin), or the like can be used. Here, a bonding material 6 constituted by a commercially available adhesive tape that can be melted is provided. Specifically, each end portion (periphery) of the insulating paper 4 constituting the connecting portion insulating layer 41 is disposed on the interlayer insulating layers 131A and 131B, respectively, and the adhesive tape is wound in the circumferential direction of the cores A and B. Both end portions of the adhesive tape are overlapped, and the overlapping portion is melted.

  The intermediate connection structure 1 includes the same number of connection wire layers as the number of the cable wire layers constituting the superconducting conductor included in the pair of superconducting cables to be connected (here, four layers), and the same number as the interlayer insulating layers. It has a connection insulation layer (here 3 layers). In addition, the intermediate connection structure 1 includes a reinforcing insulating layer (not shown) on the outer periphery of the outermost connection portion wire layer. The reinforcing insulating layer can be formed by winding insulating paper such as kraft paper or semi-synthetic insulating paper such as PPLP (registered trademark). In the intermediate connection structure 1, by providing the connection sleeve 2 having a relatively small diameter as described above, the stress cone provided in the reinforcing insulating layer can be made small, and a small and thin reinforcing insulating layer can be obtained. An electric field shielding layer formed by winding a conductive material such as crepe carbon paper or annealed copper wire can be provided on the outer periphery of the reinforcing insulating layer.

  Further, the intermediate connection structure 1 further includes a normal conductive connection portion when the outer periphery of the reinforcing insulating layer (or the electric field shielding layer) includes a shield connection portion and a normal conductive layer between the superconductive shield layers. The shield connection part is formed of a member made of a normal conductive material such as a copper tape, and the normal conductive connection part is formed of a member made of the above-mentioned superconducting wire or normal conductive material.

[Connection method of intermediate connection structure]
Next, a procedure for constructing the intermediate connection structure 1 and a connection member 30 (FIG. 2) used for construction will be described.

  First, the cable core (core A, core B) is pulled out from the ends of the pair of superconducting cables to be connected, the connecting ends of the cores A, B are stepped off, and the former 110A, 110B, the cable wire layer constituting the superconducting conductor 121A, 122A, ..., 121B, 122B, ..., interlayer insulating layers 131A, ..., 131B, ..., the electric insulating layer, the superconducting shield layer, and the normal conductive layer are exposed in a stepped manner.

  .., 121B, 122B,..., The cut pieces obtained by cutting the superconducting wires constituting the cable wire layers 121A, 122A,... 121B, 122B,. The connection member 30 is used for the production of the connection portion wire layers 31, 32,..., And as shown in FIG. 2, a plurality of connection superconducting wires 3 arranged in parallel are provided at a plurality of temporary intervals. This is an interdigital member integrated by the fixing member 30t. Here, the connecting portion wire layers 31, 32,... Pass the superconducting wire 3 for connection one by one between the cable wire layers {121A, 121B}, between {122A, 122B},. It can be constructed by repeating the process of fixing both ends of the wire to the superconducting wire constituting the cable wire layer by the wire joining layer 5 respectively. However, in this case, the number of processes is large. Further, if the connecting superconducting wires 3 are wound and arranged one by one in a spiral according to a predetermined spiral pitch as described above, manufacturing errors tend to increase. On the other hand, when the connection member 30 is produced and used in advance, a plurality of parallel superconducting wires 3 for connection can be arranged at once on the outer periphery of the connection sleeve 2 (FIG. 1), etc. In addition to being easy, manufacturing errors are small, and the connecting portion wire layers 31, 32,... Can be formed with high accuracy.

  First, a pattern 30p having a parallelogram shape in plan view is produced using the above-described cut piece as a spiral pitch mold. One side of the pattern 30p has an angle corresponding to the spiral pitch and a length necessary for the connection wire layer (the likelihood corresponding to the spiral pitch is added to the length between the cable wire layers connected by the connection wire layer). The other side is a side having a length corresponding to the outer peripheral length of the cable wire layer connected by the connection portion wire layer. Cut the superconducting wire prepared separately along one side of the above-mentioned pattern 30p, and the required number of superconducting wires 3 for connection having a predetermined length (the same number as the number of superconducting wires constituting the cable wire layer as described above) prepare. Then, the connecting superconductor wires 3 are arranged along the obtained pattern 30p, and the temporary fixing members 30t are appropriately arranged so as to cross the parallel wires 3, whereby the connecting member 30 is obtained. In FIG. 2, although it looks flat, depending on the helical pitch, the connecting superconducting wire 3 is arranged in a wavy state.

  Since the temporary fixing member 30t is removed after the connecting superconducting wire 3 is joined to the cable wire layer, an appropriate adhesive tape that does not have electrical insulation or resistance to a refrigerant can be used. Also, as described in Patent Document 1, the wire bonding layer 5 can be formed in advance at both ends of the connecting superconducting wire 3 with solder paste or the like.

  Note that the insulating paper constituting the connecting portion insulating layer can also be produced by using a cut piece obtained by cutting the insulating paper constituting the interlayer insulating layer as a mold.

  A pair of formers 110A and 110B to be connected are inserted into the through holes of the connection sleeve 2, the end surfaces of the formers 110A and 110B are butted together, and the formers 110A and 110B and the connection sleeve 2 are compressed at the same time. Connecting. Here, the connection sleeve 2 is compressed so that the outer diameter of the connecting sleeve 2 is substantially equal to the outer diameter of the formers 110A and 110B.

  A conductive tape such as the above-mentioned crepe carbon paper is wound around the outer periphery of the cushion layer 112A of the core A, the outer periphery of the connection sleeve 2, and the outer periphery of the cushion layer 112B of the core B, and connected so as to cross between the cushion layers 112A and 112B. Part cushion layer 7 is formed. The ends of the conductive tape are difficult to slip when sandwiched between the tapes constituting the cushion layers 112A and 112B or fixed with an appropriate adhesive tape.

  The connection member 30 described above is wound around the outer periphery of the cable wire layer 121A of the core A, the outer periphery of the connection portion cushion layer 7, and the outer periphery of the cable wire layer 121B of the core B. Then, one end of each connecting superconducting wire 3 provided in connecting member 30 is connected to each superconducting wire 12A (FIG. 3A) constituting cable wire layer 121A, and the other end of each connecting superconducting wire 3 is cabled. It joins to each superconducting wire 12B (FIG. 3 (A)) constituting the wire layer 121B. As described above, since the plurality of superconducting wires 3 for connection are integrated by the temporarily fixing material 30t, each wire 3 is easily wound at a time on the same helical pitch as the helical pitch of the cable wire layers 121A and 121B. Can turn. Further, since the connecting superconducting wire 3 is integrated by the temporary fixing member 30t, the adjacent wires 3 are not displaced in the above-described joining operation, and can be joined to the superconducting wires 12A and 12B with high accuracy.

  When all the superconducting wires 3 for connection provided in the joining member 30 have been joined, the temporary fixing material 30t is removed. By this step, as shown in FIG. 3 (A), the connecting portion composed of the connecting superconducting wire 3 arranged at the same helical pitch as the superconducting wire 12A, 12B constituting the cable wire layers 121A, 121B. A wire layer 31 can be constructed. The end portion and the intermediate portion of the connecting superconducting wire 3 may be appropriately fixed by the bonding material 9 so that the connecting superconducting wire 3 does not come apart. The bonding material 9 can be the same as the bonding material 6 described above.

  Next, as shown in FIG. 3B, the interlayer insulating layers 131A and 131B are formed on the outer periphery of the interlayer insulating layer 131A of the core A, the outer periphery of the connecting portion wire layer 31, and the outer periphery of the interlayer insulating layer 131B of the core B. A wide insulating paper 4 having a spiral pitch similar to the spiral pitch of the insulating paper is disposed and wound, and both edges of the insulating paper 4 are fixed by the bonding material 6 (FIG. 1). By this step, the connection part insulating layer 41 (FIG. 1) can be constructed on the outer periphery of the connection part wire layer 31.

  In the same manner, the connecting portion between the superconducting conductor of the core A and the superconducting conductor of the core B can be constructed by alternately producing the connecting portion wire layer 32, the connecting portion insulating layer 42,. A reinforcing insulating layer, a shield connection part, and the like are constructed on the outer periphery of the connection part. A known method can be used to construct a reinforcing insulating layer, a shield connection portion, and the like.

  The intermediate connection structure 1 that connects the cable cores of the pair of superconducting cables can be constructed by the above-described steps. In the case of a multi-core cable, the above steps are repeated. On the outer periphery of the intermediate connection structure 1, a connection box (not shown) filled with a refrigerant such as liquid nitrogen is constructed. In the case of a multi-core cable, a plurality of intermediate connection structures may be housed in a single connection box, or each intermediate connection structure may be housed in a separate connection box. A known connection box can be used.

[effect]
The intermediate connection structure 1 having the above configuration includes an interlayer insulation layer (connection insulation layers 41, 42,...) Not only in the cable portion but also in the connection place, so that even when used for AC power transmission. The loss due to the skin effect is small and the loss is low. In particular, in the intermediate connection structure 1 of the first embodiment, the cable wire layers and the connection portion wire layers 31, 32,... Are provided by including the connection portion insulating layers 41, 42,. Current can be made to flow uniformly, and AC loss can be reduced.

  Further, in the intermediate connection structure 1 of the first embodiment, the connection superconducting wire constituting the connecting portion wire layer connecting the cable wire layers included in the superconducting conductor is the same as the helical pitch of the superconducting wire constituting the cable wire layer. The connection resistance is small by being spirally wound at the helical pitch. Also from this point, the intermediate connection structure 1 has low loss.

  Further, in the intermediate connection structure 1 of the first embodiment, the insulating paper 4 constituting the connecting portion insulating layers 41, 42,... Is spirally wound at a helical pitch similar to that of the insulating paper constituting the interlayer insulating layer. By being turned, it is possible to prevent buckling and damage of the connecting superconducting wire 3 constituting the connecting portion wire layers 31, 32,...

  In addition, when the intermediate connection structure 1 is constructed, the connection member 30 is used, so that when the plurality of connection superconducting wires 3 are arranged in a spiral shape as described above, the wires 3 are easy to handle and have excellent workability. In particular, in producing the connection member 30, by using a cut piece of the superconducting wire cut as a pattern, and preparing the connection superconducting wire 3 based on this pattern, the one corresponding to the actual helical pitch can be accurately produced. it can. As a result, the superconducting wire constituting the cable wire layer and the connecting superconducting wire 3 can be joined with high accuracy, and manufacturing errors can be reduced.

  In addition, the intermediate connection structure 1 is small because the outer diameter of the connection sleeve 2 is small, so that the reinforcing insulating layer can be small.

<Modification 1>
In the first embodiment, the form in which both the superconducting wire constituting the cable wire layer and the connecting superconducting wire constituting the connecting portion wire layer are thin film wires has been described. In addition, it can be set as the form whose both wires are Bi type | system | group wires. Since the Bi-based wire does not have a metal substrate like a thin film wire, there is no need to consider the front and back when joining the wires, and the workability at the time of connection is excellent. Also in this embodiment, the connection superconducting wire constituting the connecting portion wire layer is spirally wound at the same helical pitch as the superconducting wire constituting the cable wire layer. Resistance can also be reduced.

  Or the superconducting wire which comprises a cable wire layer, and the connection superconducting wire which comprises a connection part wire layer can be made into a different form. For example, when a Bi-based wire is used for the superconducting wire for connection, the connection work can be easily performed as described above.

<Modification 2>
In the first embodiment, the connection superconducting wire constituting the plurality of connecting portion wire layers has been described as being of the same material. In addition, among the plurality of connecting portion wire layers, a part of the layers may be formed of a different kind of wire such as a thin film wire and the other layer may be a Bi-based wire. In this embodiment, in particular, when the thin film wire is disposed on the outer peripheral side, even when the thin film wire is used for AC power transmission, current can be passed efficiently. Further, in this embodiment, the workability can be improved by providing the Bi-based wire material having excellent workability at the time of connection as described above.

  The present invention is not limited to the above-described embodiment, and can be modified as appropriate without departing from the gist of the present invention.

  The intermediate connection structure of the superconducting cable of the present invention can be suitably used at a connection location between the superconducting cables, particularly at a connection location between the superconducting cables provided in the power supply path used for AC power transmission. The connection method of the superconducting cable of the present invention can be suitably used when a connection point between the superconducting cables is constructed at a laying site or in a factory (when a factory joint is constructed).

1 Intermediate connection structure of superconducting cable 2 Connection sleeve 3 Superconducting wire for connection
4 Insulating paper 5 Wire bonding layer 6,9 Bonding material 7 Cushion layer of connecting part
12A, 12B superconducting wire
30 Connecting material 30t Temporary fixing material 30p
31,32 Connection wire layer 41,42 Connection insulation layer
1000 Superconducting cable 100 Cable core
110,110A, 110B Former 112,112A, 112B Cushion layer 120 Superconducting conductor
121,122,123,124,121A, 122A, 121B, 122B Cable wire layer
130,131,132,133,131A, 131B Interlayer insulation layer
140 Electrical insulation layer 150 Superconducting shield layer 160 Normal conducting layer 170 Protective layer
200 Heat insulation pipe 201 Inner pipe 202 Outer pipe 203 Heat insulation 210 Corrosion protection layer

Claims (8)

A superconducting cable for connecting superconducting cables having a superconducting conductor in which a cable wire layer formed by spirally winding a superconducting wire around the former is laminated and an interlayer insulating layer interposed between the cable wire layers. Intermediate connection structure of
Constructed from a conductive material, connecting the formers included in each superconducting cable, and having an outer diameter equal to or greater than the outer diameter of the former and not more than the outer diameter of the cable wire layer located on the outermost side of the superconducting conductor A connection sleeve;
A connection portion wire layer that connects the superconducting wires that constitute the cable wire layer included in each superconducting cable, and is composed of a plurality of superconducting wires for connection arranged in parallel,
It is composed of an insulating material, is arranged so as to cross between the interlayer insulating layers included in each superconducting cable, and includes a connecting portion insulating layer interposed between the connecting portion wire layers stacked in multiple layers. Intermediate connection structure for superconducting cables.   2. The connection superconducting wire constituting the connection portion wire layer is spirally wound at a spiral pitch similar to that of the superconducting wire constituting the cable wire layer. Intermediate connection structure of the described superconducting cable.   3. The superconducting cable intermediate connection structure according to claim 1, wherein the superconducting wire and the connecting superconducting wire are thin film wires each having a superconducting thin film on a metal substrate.   The superconducting wire is disposed with the superconducting thin film facing toward the outer peripheral side, and the superconducting wire for connection is disposed with the superconducting thin film facing toward the inner peripheral side, and the superconducting thin films are joined with both superconducting thin films facing each other. The intermediate connection structure for a superconducting cable according to claim 3, wherein: The connection part insulating layer is constituted by winding at least one kind of insulating paper of wide insulating paper, narrow insulating paper, and crepe insulating paper,
5. The intermediate connection structure for a superconducting cable according to claim 1, wherein the insulating paper is fixed to the interlayer insulating layer with a bonding material.
However, the wide insulating paper is such that the length of one side arranged substantially along the axial direction of the superconducting cable is not less than the length between the interlayer insulating layers provided in each superconducting cable, and the narrow insulating paper The paper has a width equal to or greater than the width of the insulating paper constituting the interlayer insulating layer and not more than the length of the one side of the wide insulating paper.   6. The intermediate connection structure for a superconducting cable according to claim 5, wherein the insulating paper is spirally wound at a helical pitch similar to that of the insulating paper constituting the interlayer insulating layer. A superconducting cable comprising a superconducting conductor in which a cable wire layer formed by spirally winding a superconducting wire on the outer periphery of the former is laminated and an interlayer insulating layer interposed between the cable wire layers is connected between the superconducting cables. A superconducting cable connection method for constructing a connection structure,
Step of stripping the connection end of each superconducting cable, exposing the former, the cable wire layer, and the interlayer insulating layer in a stepwise manner,
The former included in each superconducting cable is inserted into a connection sleeve made of a conductive material, and the outer diameter of the connection sleeve is equal to or greater than the outer diameter of the former, and is outside of the cable wire layer located on the outermost side of the superconducting conductor. Compressing the connection sleeve so as to have a diameter or less, and connecting the formers;
A connection member formed by temporarily fixing a plurality of parallel connection superconducting wires in an interdigital shape is wound around the outer periphery of the connection sleeve, and the connection superconducting wire is provided between the cable wire layers provided in each superconducting cable, Joining the superconducting wire constituting the cable wire layer and the superconducting wire for connection, and connecting the cable wire layers;
A method of connecting a superconducting cable, comprising: disposing an insulating material on an outer periphery of the connecting superconducting wire to form a connecting portion insulating layer across the interlayer insulating layers included in each superconducting cable.   The connecting member uses a cut piece of the superconducting wire cut from the superconducting cable by stripping to produce a paper pattern having a helical pitch similar to that of the superconducting wire, and the superconducting wire prepared separately is used as the paper pattern. The connection superconducting wire is produced by cutting along the line, and the plurality of produced connection superconducting wires are arranged in parallel along the pattern and formed by integrating with a temporary fixing material. 8. The method for connecting a superconducting cable according to claim 7.

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