HK1071470B - Terminal structure of superconducting cable and superconducting cable line therewith - Google Patents

Description

End structure of superconducting cable and superconducting cable line using the same

Technical Field

The present invention relates to a terminal structure of a superconducting cable including a cable core having a superconducting layer, and a superconducting cable line including the terminal structure, and more particularly, to a terminal structure of a superconducting cable and a line including the terminal structure, which facilitate connection of a ground wire to the superconducting layer while preventing insulation of an electrically insulating layer from being impaired.

Background

As a superconducting cable manufactured using a superconducting conductor layer formed of, for example, a Bi-based high-temperature superconducting tape (tape), not only a single-phase cable including a single cable core but also a multi-core type superconducting cable manufactured by assembling a plurality of cable cores into one unit is under development.

Referring to fig. 5, a superconducting cable 100 includes three cable cores 102 wound and accommodated in a thermal insulation pipe 101. The thermally insulated pipe 101 has an outer pipe 101a and an inner pipe 101 b. A double pipe composed of these outer pipe 101a and inner pipe 101b is provided therein with a thermal insulating material (not shown), and a vacuum is generated in the double pipe.

Each of these cable cores 102 includes, in order from the innermost component, a former 200, a superconducting conductor layer 201, an electric insulation layer 202, a superconducting shield layer 203, and a protective layer 204. The superconducting conductor layer 201 is formed by spirally winding a plurality of layers of superconducting wires around the former 200. The electrical insulation layer 202 is formed by winding an insulation paper formed by laminating polypropylene kraft paper (polypropylene and kraft paper in lamination). The superconducting shield layer 203 is constituted by spirally winding a superconducting wire similar to that used for the superconducting conductor layer 201 around the electric insulation layer 202. In this superconducting shielding layer 203, in a stable state, a current is induced in substantially the same magnitude and in the opposite direction as a current flowing through the superconducting conductor layer 201. The induced current generates a magnetic field that can cancel the magnetic field generated from the superconducting conductor layer 201, and thus there is substantially no magnetic field leakage outside the cable core 102. A space 103 formed between the inner pipe 101b and each cable core 102 generally provides a passage through which the refrigerant flows. The thermal insulation layer 101 has a radially outer portion providing a corrosion resistant layer 104 of polyvinyl chloride.

In contrast to conventional electrically conductive multi-phase cables, it is known that each cable core normally has a grounded shield so that a ground potential is obtained for the phases. This technique has been described, for example, in Kihachiro Iizuka, Kabushiki Kaisha Denkishinon, march 25 1989, first edition, first printing, page 645 ", New edition Power Cable Technology Handbook. The ground wire is usually connected to the shielding layer by using typical solder soldering, pressure soldering, etc., having a melting point of about 190 c.

The superconducting cable also requires the superconducting shielding layer to be handled, and it is desirable to ground the superconducting shielding layer. If the superconducting cable has a superconducting shield layer grounded in a manner used for grounding the shield layer of a general conductive cable, however, problems arise: first, the superconducting layer is formed of a superconducting wire rod having no mechanical strength to be able to withstand pressure welding. As such, press forming as commonly used for conventional conductive cables cannot be used. If the superconducting cable has a superconducting shield layer connected to the ground line with the above-described typical solder, whose melting point is higher than the temperature limit of the electric insulation layer under the superconducting shield layer, the heat for melting the solder weakens the insulation of the electric insulation layer.

Furthermore, directly connecting the ground wire and the superconducting shielding layer of the superconducting cable may damage the superconducting wire material constituting the superconducting shielding layer and weaken the insulation of the electric insulation layer as described above. It is therefore desirable to indirectly connect the ground line to the superconducting shielding layer, rather than directly connecting the ground line to the superconducting shielding layer.

Disclosure of Invention

An object of the present invention is to provide a terminal structure of a superconducting cable such that the characteristics of a superconducting layer and a superconducting shield layer are not impaired when the superconducting layer is grounded, in particular, the insulation of an electric insulation layer is not impaired, and a superconducting cable line including the terminal structure. Another technical problem to be solved by the present invention is to provide a terminal structure of a superconducting cable in a polyphase cable, the superconducting cable having a superconducting shield layer appropriately processed to pass an induced current, and a superconducting cable line including the terminal structure.

The present invention achieves the above object by: a connection electrode is arranged radially outside the superconducting layer, and the superconducting layer and the connection electrode are also connected using a solder having a low melting point.

More specifically, the present invention is a terminal structure of a superconducting cable including a cable core having a superconducting layer and an electrically insulating layer, and further including a connection electrode arranged radially outside the superconducting layer, and the connection electrode and the superconducting layer are connected by a low melting point solder. Further, when the superconducting layers are a superconducting conductor layer and a superconducting shielding layer, the connection electrode is disposed radially outside the superconducting shielding layer, and the connection electrode has a ground line mounted thereon. Further, when the superconducting cable is a polyphase cable including a plurality of cable cores, the connection electrode is arranged radially outside the superconducting shielding layer of each cable core, and such connection electrodes are connected by the conductive coupling member.

In connection with the present invention, the superconducting cable has a superconducting layer provided with a conductive connecting member (connecting electrode) radially outside, the connecting electrode being fixed to the superconducting layer by using a low melting point solder to prevent the electrically insulating layer from having impaired insulation when the connecting member is installed. The connection electrode may have a ground wire already mounted thereon in advance, and the connection electrode having the wire can be connected to the superconducting layer and the superconducting shielding layer, in particular, avoiding the need to mount the ground wire directly to the superconducting shielding layer. This prevents the superconducting shield layer from being damaged when the ground wire is installed and also prevents the insulation of the electrically insulating layer from being weakened.

Further, if the superconducting cable is a multi-phase cable including a plurality of cable cores, each cable core may have a superconducting shielding layer provided with a connection electrode radially outside, and the superconducting shielding layer and the connection electrode may be connected by a low melting point solder, and each superconducting shielding layer may be grounded. The inventors of the present invention studied and found that when each cable core has a superconducting shielding layer grounded, the following problems arise: superconducting cables pass significantly more current than conventional conductive cables. If the superconducting shielding layer of each cable core is grounded through the ground, the superconducting shielding layer of each cable core may be disadvantageously connected through the ground. If this is done, the superconducting shield layer (large connection resistance) passes a smaller amount of current than the current flowing through the superconducting layer. Thus, the superconducting shielding layer of each cable core cannot generate a magnetic field that can cancel out the magnetic field generated by the superconducting conductor layer of each cable core, and a large magnetic field is generated outside each cable core. Thus, in the present invention, if the superconducting shielding layers of the cable core are each provided with a connection electrode on the radially outer portion thereof, the superconducting shielding layers are respectively connected together by a conductive coupling member to reduce connection impedance and short the superconducting shielding layers. A magnetic field that can cancel the magnetic field generated from the superconducting conductor layer of each cable core can be generated at each superconducting shielding layer. The magnetic field leakage from each cable core can thus be reduced.

The present invention will be described in more detail below.

The present invention relates to a superconducting cable including a cable core having a superconducting layer and an electrical insulating layer. Thus, it may be a single-phase cable comprising a single one of said cable cores, or a multi-phase cable comprising a plurality of said cable cores. A multiphase cable includes a 3-phase superconducting cable having three cable cores wound together and housed within a thermally insulated pipe. The cable may be one of any known superconducting cable.

The superconducting layer includes a superconducting conductor layer and a superconducting shield layer. It is suggested that these superconducting layers are formed by spirally winding a wire formed of a Bi 2233-based superconducting material, and that they may be provided as a single layer or a plurality of layers. For the multiple layers, an insulating paper formed of a laminated polypropylene kraft paper is wound between the layers to be provided as an insulating layer. And an electric insulating layer is interposed between the superconducting conductor layer and the superconducting shielding layer. Recommended by windingOr the like, formed by laminating polypropylene kraft paper. Further, in the present invention, a connection electrode is disposed radially outside the superconducting layer, and the superconducting layer and the connection electrode are joined together by a low-melting-point solder.

Solder has a melting point that varies depending on its chemical composition. The present invention uses a low melting point solder having a melting point of about 190 c lower than that of a commonly used solder (hereinafter referred to as a typical solder). More specifically, a solder having a melting point below the temperature limit of the electrically insulating layer is used. The electrically insulating layer is made ofOr similar insulating paper formed from polypropylene laminated kraft paper, with a temperature limit of 130 c. I.e. the typical solder, has a melting point above the temperature limit of the electrically insulating layer, which would cause the insulation of the electrically insulating layer to be impaired. Accordingly, solder having a melting point of less than 130 c (more preferably at most 120 c) is used to prevent deterioration of the insulation of the electrically insulating layer. On the other hand, it is required that the solder does not melt and has a certain level of mechanical strength in a range from a normal temperature to a particularly low temperature (temperature of the refrigerant freezing cable). The solder has such properties including a melting point of at least 60 ℃. Such a low melting point solder may be a commercially available solder.

Also, when attaching the connection electrode, the temperature sensor can be bonded on, for example, an electrically insulating layer, a superconducting shielding layer, and/or the like to determine the temperature of each layer to better prevent the insulation of the electrically insulating layer from being weakened. The temperature sensor includes a thermocouple or the like. It is recommended that the temperature sensor may be attached with a tape, solder, or the like, and removed after the connection electrode is connected to the radially outer portion of the superconducting layer with a low melting point solder.

The connection electrode is used to connect a ground line, a superconducting layer and/or the like together. Such a connection electrode is preferably made of a conductive material such as copper or aluminum (both of which have a specific impedance ρ of 2 × 10 at 77K)^-7Ω · cm) or the like, which has a small electric power at a refrigerant temperature used for the superconducting cable (for example, around a liquid nitrogen temperature when liquid nitrogen is used as the refrigerant)Impedance. The connection electrode is preferably shaped to contact at least a part of the superconducting layer in the circumferential direction. If the superconducting layer is formed of a plurality of superconducting wires, in particular, the connection electrode is preferably in a shape capable of being electrically connected together with all the constituent superconducting wires. For example, it comprises a cylindrical shape capable of covering the entire outer periphery of the superconducting layer. If the connection electrode is cylindrical, it is preferably formed by bonding together sheets having an arc-shaped cross section to form a cylinder to facilitate attachment of the connection electrode at the periphery of the superconducting layer. More specifically, combined sheets each having a semicircular arc sectional shape are included in the connection electrode.

The connection electrode preferably has a ground wire connected thereto, and by connecting the connection electrode connected to the ground wire to the superconducting layer radially outside the superconducting layer, the superconducting shielding layer can be particularly prevented from being damaged when the ground wire is connected, and the insulation of the electrically insulating layer can be prevented from being impaired. Moreover, the use of the connection electrode connected to the ground wire can facilitate grounding of the superconducting shielding layer. The ground wire is connected to the connection electrode by means of solder or bolts or pressure bonding or similar mechanical connection means. In the present invention, the superconducting layer has a ground line connected thereto through a connection electrode. Thus, such a mechanical connection as described above can also be employed, and the ground wire is easily and reliably connected. Moreover, the connection electrode can be connected to the superconducting cable at any desired position, providing good operability. Further, the degree of freedom in selecting the connection position of the connection electrode can be improved for the multi-phase cable.

For a multi-phase cable including a plurality of cable cores, it is recommended that the superconducting layers (particularly, superconducting shielding layers) of the respective cable cores be provided thereon with connection electrodes, respectively, as described above, and that these connection electrodes be connected by a conductive coupling member to short the superconducting shielding layers, and that a ground line attached to the connection electrode associated with any one cable core be able to be grounded to commonly ground the plurality of cable cores. It is sufficient to note that any single cable core is provided with a connection electrode to which a ground wire is mounted. The other cable cores may be provided with connection electrodes to which no ground wire is attached, respectively.

For example, for a 3-phase superconducting cable including three cable cores, the connection electrode and the coupling member are connected by a form of so-called Y-connection. More specifically, the radially outer portions of the cable cores are respectively provided with respective connection electrodes, one ends of respective coupling members are respectively mounted on the respective connection electrodes, and the respective other ends of the coupling members are connected toward the center of a triangle having the connection electrodes as vertexes. Alternatively, a form of connection known as a delta connection is also conceivable. More specifically, the radially outer portions of the cable cores are respectively provided with respective connection electrodes which serve as vertices and to which the coupling members are connected such that the coupling members correspond to the sides of the connection vertices (or connection electrodes). For the Y-connection form, the coupling parts may be connected by using a separate center electrode to connect the respective other ends of the coupling parts to the center electrode so that the respective other ends are connected.

The coupling member is preferably made of a flexible material. More particularly, it includes materials made of, for example, a woven material. Such a flexible coupling member allows to follow the movement of the cable core when the cable core is cooled down to contract. When the cable core contracts, tension is induced. However, the tensile force is exerted mainly on the flexible coupling member and rarely on the low melting point solder having a lower mechanical strength than the above-mentioned typical solder. Thus, the portion of the low melting point solder can be effectively protected. Moreover, if the present terminal structure corresponding to the multi-phase cable is accommodated in the distribution box, the flexible coupling member can provide good operability when connecting the connection electrodes in the distribution box having a limited space, and can absorb dimensional errors such as positional deviation, deformation, and the like, which are generated when the electrodes are connected. If such a flexible coupling member is used, for example, the connection electrodes are connected in the above-described Y-connection manner, the coupling member may be mounted such that the portion of the connection electrode where the coupling member is mounted and the portion (or center electrode) connecting such coupling members together have the same position as viewed along the cable core, even if the portion is offset as viewed along the core, which may facilitate mounting of the coupling member.

It is recommended that the connection electrode be mounted such that the protective layer is removed and the superconducting layer (particularly, the superconducting shielding layer) is exposed. In this way, the insulating property of the electrically insulating layer is more effectively prevented from being impaired, and it is preferable that the connection electrode and the electrically insulating layer are thermally insulated. Such as a tape, sheet, or the like formed of a thermally insulating material, is wound between the superconducting shielding layer and the electrically insulating layer. The thermal insulation material includes glass, Fiber Reinforced Plastic (FRP), and the like. If the superconducting shielding layer has a plurality of layers each having a connection electrode connected thereto at different axial length portions, connection resistance may vary and bias current distribution may be introduced. Thus, it is desirable that the axial lengths be equal. Thus, if the superconducting shielding layer is a plurality of layers, each layer may be segmented at a portion connected to the connection electrode, and the innermost layer (the layer located closest to the electrically insulating layer) is cut so that the axial length of the innermost layer is equal to the axial length of the other segmented layers to partially expose the electrically insulating layer. Preferably, the exposed electrically insulating layer has the periphery described above, around which a thermally insulating tape or the like is wound, and the connection electrode is mounted thereon. Also, the exposed electrically insulating layer may further have a temperature sensor attached thereto to determine the temperature of the layer when a low melting point solder is used to mount the connection electrode to the radially outer portion of the superconducting layer.

The terminal structure is used in a superconducting cable line, such as in a connection of a superconducting cable and a general conductive cable, a connection of a superconducting cable, or a portion where a terminal structure is provided such that the terminal structure is provided at both ends of the superconducting cable. Such a portion is a portion where the cable termination is processed to form a connection structure, a termination structure, etc., and the connection electrode can be easily arranged.

For a multi-phase cable comprising a plurality of cable cores, the above-described connection structure, termination structure, and the like are formed by separating each phase, i.e., each cable core. The separated cable cores are accommodated in a distribution box. More specifically, the more the multiphase cable cores assembled in the assembly portion become wider as they extend therefrom, the wider the spacing therebetween, the cable cores then being accommodated in the distribution box. The distribution box has a thermal insulation structure, and is filled with a refrigerant such as liquid nitrogen to cool the core.

Each cable core protruding from the inside of the tank is provided with a heat insulating pipe filled with a refrigerant such as liquid nitrogen to maintain a superconducting-like state held in the tank. Thus, it is very troublesome to mount the connection electrodes to the superconducting shielding layers of the respective cable cores extending from the distribution box. The connection electrodes may be mounted to the superconducting layers of the respective cable cores extending from the distribution box. Preferably, however, the connection electrode is also mounted on the cable core in the distribution box, thus allowing excellent workability in mounting the connection electrode.

It is recommended that each cable core in the distribution box is held by a holding tool. The holding means comprise means capable of holding each cable core and also keeping each cable core separate. In particular, the holding tool preferably has a structure capable of moving within the distribution box when the cable core is extended and retracted.

Also for a multiphase cable, the superconducting layers (in particular the superconducting shielding layers) are preferably grounded only at one end of the cable head and not at the other end of the cable head, since for a superconducting cable, grounding at both ends will form a closed loop via earth and connect the superconducting shielding layers together through earth.

Therefore, as described above, in the terminal structure of the present superconducting cable, the radially outer portion of the superconducting layer of the cable core may be provided with the connection electrode having the ground wire mounted thereon to effectively prevent the superconducting layer from being damaged when the ground wire is mounted and to prevent the insulation of the electrically insulating layer from being weakened. Also, for a multi-phase cable, the connection electrodes can be connected together to short the superconducting shielding layer. In this manner, the superconducting shielding layer of each cable core can generate a magnetic field that cancels out the magnetic field generated from each superconducting conductor layer, and can prevent a large magnetic field from being generated outside each cable core. In particular, in the present invention, the superconducting layer and the connection electrode can be connected with a low-melting-point solder, and the mounting of the connection electrode does not impair the insulation of the electrically insulating layer.

The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.

Drawings

Fig. 1 schematically shows a terminal structure of a superconducting cable related to the present invention;

fig. 2A schematically shows the structure of the connection electrode arranged around the superconducting shielding layer, and fig. 2B shows a partial cutaway view of the connection electrode arranged on the radially outer portion of the superconducting shielding layer on a portion of the cable core;

FIG. 3 is a schematic cross-sectional view of a Y-shaped connection pattern connecting electrodes and coupling members;

FIG. 4 is a schematic cross-sectional view of a delta connection pattern connecting the electrodes and the coupling member;

fig. 5 is a sectional view of a 3-phase superconducting cable simultaneously using three cores.

Detailed Description

Embodiments of the present invention will be described below.

Fig. 1 shows a superconducting cable line 300 including a termination structure of a superconducting cable 100. The termination structure of the superconducting cable 100 is a termination structure of a multiphase superconducting cable including a plurality of cable cores 102 having superconducting layers and electrical insulating layers, and each cable core 102 has a superconducting layer (a superconducting shielding layer in the present embodiment) surrounded by the connection electrode 1. The superconducting shield layer and the connection electrode 1 are joined by a low melting point solder. In the present embodiment, a 3-phase superconducting cable 100 including three cable cores 102 will be used as an illustrative example.

The present embodiment uses a 3-phase superconducting cable 100 having a structure similar to that of the 3-phase superconducting cable shown in fig. 5. More specifically, looking radially outward, cable core 102 includes former 200, superconducting conductor layer 201, electrical insulation layer 202, superconducting shield layer 203, and protective layer 204. For 3In a phase superconducting cable 100, three cable cores 102 are wound together and housed in a thermal insulation pipe 101. The form 200 is constructed by winding a plurality of copper wires, each covered with an insulator. The superconducting conductor layer 201 and the superconducting shield layer 203 are constituted by spirally winding a Bi 2223-based superconducting strip line (Ag — Mn shield line) in layers around the former 200 and the electrical insulating layer 202, respectively. The electrically insulating layer 202 is formed by winding kraft paper (polypropylene laminated paper manufactured by Sumitomo electronics limited) laminated with polypropylene around the superconducting conductor layer 201) Formed of insulating paper. The protective layer 204 is constituted by winding kraft paper around the superconducting shield layer 203. The heat-insulating pipe 101 is an SUS corrugated pipe. Insulators are arranged in layers between the outer pipe 101a and the inner pipe 101 b. The pipes 101a and 101b form a double pipe, the inside of which is vacuum. More specifically, the thermally insulated pipe 101 has a vacuum multi-layer thermally insulated structure. The radially outer portion of the thermally insulated pipe 101 is provided with a corrosion resistant layer 104 of polyvinyl chloride.

The above-mentioned 3-phase superconducting cable 100 is twisted and accommodated in a thermal insulation pipe 101, and at the end portion, a cable core 102 is divided and thereby divided and accommodated in a branch box 3009. The separate cable cores 102 thus each have a respective superconducting shielding layer on the radially outer side of which the connection electrode 1 is respectively arranged, and the connection electrode 1 and the conductive coupling member 2 are connected to electrically connect the superconducting shielding layers or the shorting layers together.

Referring to fig. 2A and 2B, the connecting electrode 1 comprises semicircular arc-shaped pieces 1a and 1B, seen in cross-section, joined together to provide a cylindrical geometry. The tabs 1a and 1b each have an open edge of a flange 1c arranged extending along the connection electrode 1. The flanges of the respective sheets 1a and 1b face each other, bolts or similar fasteners are inserted through holes (not shown) and clamped together by screwing nuts to form the cylindrical geometry. One sheet 1a has a fixing member 1d to which a coupling member 2 described below is connected, and a hole 1e introduces a low melting point solder between the connection electrode 1 and the superconducting shielding layer. In the present embodiment, two holes 1e are shown as an example, and a single hole 1e may be provided. In the present embodiment, the connection electrode 1 is formed of copper.

Bonding the connection electrode 1 causes the protective layer 204 of the cable core 102 to be removed to expose the superconducting shielding layer 203. In the present embodiment, the superconducting shielding layer 203 is provided as two layers having an inner layer 203a and an outer layer 203 b. It is recommended that the layer be peeled off stepwise so that the superconducting wires constituting each of the layers 203a and 203b can contact the low melting point solder 5.

Further, the connection electrode 1 not only short-circuits the superconducting shielding layer 203 but also can be connected to the ground line 3. In the present embodiment, as shown in fig. 2A and 2B, the ground line 3 is connected to the segment 1B. Alternatively, the ground wire 3 may be connected to the segment 1 a. The ground wire 3 may be connected using a typical solder.

Referring to fig. 1, in the present embodiment, the coupling member 2 is formed of a braided material of copper. Also, in the present embodiment, the connection electrode 1 and the coupling member 2 are connected in a Y-connection, and the coupling members 2 are connected together by the center electrode 4 which is separately provided. In the present embodiment, the fixing member 1d and the center electrode 4 are disposed offset as viewed in the length direction, and the coupling member 2 is connected at one end to the fixing member 1d and at the other end to the center electrode 4 such that the coupling member 2 is arranged along the cable core 102.

The center electrode 4 is formed of a conductive material (copper in the present embodiment) and includes a ring 4a at the center and connection portions 4b arranged at equal intervals on the periphery of the ring 4a to connect the coupling parts 2. The long bolt 305 is fixed between the first and second holding tools 301b and 302 that hold the cable core 102, as described below, the long bolt 305 is inserted into the ring 4a, and the center electrode 4 is fixed to the long bolt 305. In this way, when the cable is cooled and the cable 102 is thus moved by contraction, the connection electrode 1 and the center electrode 4 can follow the movement of the core 102 when the coupling part 2 is bent and extended while being fixed. Moreover, the tension caused by the contraction of the cable core 102 is mostly applied to the flexible coupling member 2, and the low melting point solder is hardly subjected to the tension. It is therefore possible to prevent the connection electrode 1 from being removed from the superconducting shielding layer 203 when the cable core 102 is extended and contracted.

The connection electrode 1 is arranged on the radially outer portion of the superconducting shielding layer 203 in the process described below with reference to fig. 2A and 2B. At the end portion of the superconducting cable, the cable cores 102 are separated and each cable core 102 is removed with the protective layer on the portion provided with the connection electrode 1 to expose the superconducting shielding layer 203. In the present embodiment, the cable core is stripped in sections to allow both the inner and outer layers 203a and 203b of the superconducting shielding layer 203 to be exposed, and the interlayer insulating layer (layer formed by winding the electrically insulating paper) between the inner and outer layers 203a and 203b is removed. Also in the present embodiment, the inner layer 203a is cut to expose a portion of the electrical insulating layer 202 so that the inner layer 203a has an axial length equal to that of the outer layer 203b at a portion connected to the connection electrode 1. The exposed superconducting shielding layer 203 and the electrically insulating layer 202 may have a thermocouple bonded thereto to determine the temperature of each layer.

The exposed electrical insulation layer 202 preferably has a radially outer portion provided with a thermal insulation layer 6 to prevent the insulation from being impaired by the transferred heat at the time of welding. The thermal insulation layer 6 is formed of, for example, a glass fiber cloth tape (glass fiber tape). Further, if the low melting point solder 5 is not used on a portion of the superconducting shielding layer 203, it is recommended that the portion be masked. If solder 5 is used on a portion of layer 203, the portion is preferably plated with solder (solder-plated) to help the low melting point solder 5 adhere to the portion. Further, it is possible to perform the solder plating easily by, for example, polishing or washing the surface of the superconducting shielding layer. The layers may be solder plated as the temperature of each layer is determined by a thermocouple.

The connection electrode 1 is arranged on the radially outer portion of the superconducting shielding layer 203. The connection electrode 1 passes a current to the superconducting shielding layer 203 at the fixing piece 1 d. And thus the connection resistance of the portion near the fixing member 1d is small. In the superconducting tape line (superconducting tape line) constituting the inner layer 203a and the outer layer 203b of the superconducting shielding layer 203, the line connection resistance close to the anchor 1d is small, and the line connection resistance far from the anchor 1d is large. In other words, both the inner and outer layers 203a and 203b change the circumferential connection resistance depending on the relative position with the mount 1 d. Therefore, in the present embodiment, as shown in fig. 2B, the connection electrode 1 is disposed such that the connection position of the connection electrode 1 and the superconducting shielding layer 203 is as far away from the fixing member 1d as possible. Also in the present embodiment, the pieces 1a and 1b are arranged to cover the superconducting shielding layer 203, and the flanges 1c of the pieces 1a and 1b face each other and are clamped with bolts to fixedly connect the electrodes 1 at the radially outer portions of the superconducting shielding layer 203. As such, in the vicinity of the hole 1e for introducing the low melting point solder formed in the connection electrode 1, it is possible to attach a thermocouple by a tape or the like to determine the temperature of the connection electrode 1. Furthermore, it is possible to insert a spacer or wind a thermal resistance tape or provide a similar sealing member to prevent the low melting point solder from leaking between the flanges 1c of the two sheets 1a and 1b and from the opposite ends of the connection electrode 1. The spacers arranged between the flanges 1c comprise silver, indium or other similar soft material. The thermal impedance band includes a glass band or the like.

The low melting point solder is introduced through the hole 1 e. Thus, a heating device for keeping the solder in a liquid state is required. If the heating means is a burner, a soldering iron, or the like, a part of the connection electrode 1 is heated to a high temperature and the insulation of the thermal insulation layer 202 under the part may be weakened. Therefore, the heater is used as a heating means, and is bonded to cover the radially outer portion of the heating electrode 1. The connection electrode 1 can thus be heated uniformly. It is desirable to monitor the thermocouple and adjust the output of the heater to prevent the temperature of the thermally insulating layer 202 from exceeding 130 c, with a preferred temperature setting of 120 c or less, while introducing low melting point solder. The low melting point solder in this embodiment is a solder having a melting point of about 78 deg.c (chemical composition: Sn 9.3% by mass, Pb 34.5% by mass, Bi 50% by mass, and Cd 6.2% by mass). When solder is introduced, the thermocouple and seal, etc. are removed. Therefore, a structure for joining the electrode 1 and the superconducting shielding layer 203 by low-melting-point solder can be provided.

After the connection electrodes 1 are respectively provided on the radially outer portions of the superconducting shielding layers 203 of the cable core 102, the connection electrodes 1 are connected together by the coupling member 2 to short-circuit the superconducting shielding layers 203. More specifically, the coupling member 2 has one end connected to the fixing member 1d of the connection electrode 1 by a bolt and the other end connected to the center electrode 4 at the connecting portion 4b by a bolt. The cable cores 102 can thus each have a superconducting shielding layer 203 shorted together.

With the 3-phase superconducting cable described in the present embodiment, one of the three cable cores 102 is provided with the connection electrode 1 to which the ground wire 3 has been connected first. Since the three cable cores 102 each have the superconducting shielding layer 203 shorted by the connection electrode 1, the coupling member 2, and the center electrode 4, the grounded ground line 3 can commonly ground the superconducting shielding layers 203 of the three cable cores 102. Preferably, the termination structure of fig. 1 is disposed at opposite ends of superconducting cable 100, which is grounded at only one end, so that cable core 102 does not ground superconducting shield 203.

In the present terminal structure, the connection electrode can be disposed on the radially outer portion of the superconducting shielding layer and have a ground line connected thereto to prevent the superconducting shielding layer from being damaged at the time of connecting the ground line and to prevent the insulation of the electrical insulation layer under the superconducting shielding layer from being damaged. In particular, when the connection electrode and the superconducting shielding layer can be connected by the low melting point solder, it is possible to effectively prevent the insulation of the electrically insulating layer from being weakened when the connection electrode is attached. Further, when a current flows in the cable, the conductive coupling member connecting the electrode and the respective superconducting shielding layers of the cable core provides a short between the superconducting shielding layers. In other words, in the present invention, the connection of the superconducting shielding layers has a small interconnection resistance, and the magnitude of the current flowing through each superconducting shielding layer is substantially equal to the current flowing through each superconducting conductor layer, respectively. In this manner, a magnetic field sufficient to cancel the magnetic field generated from each superconducting layer can be generated to prevent a large magnetic field from being generated outside each cable core. Also, the shorted superconducting shielding layers can be commonly grounded and thus effective.

Note that the portion of the cable core 102 that is separated and provided with the connection electrode 1 is accommodated in the distribution box 3009. The distribution box 3009 accommodates 3 cable cores 102 such that the spacing therebetween is widened more. Also, it is preferable that the distribution box 3009 has a thermal insulation structure when it is filled with liquid nitrogen or a similar refrigerant to cool the core 102 accommodated therein. The reticle pod 3009 is cylindrical in geometry in this embodiment. The ground wire 3 connected to the connection electrode 1 is drawn out from the distribution box 3009 and grounded. It is recommended that the earth wire 3 and the distribution box 3009 be sealed to maintain airtightness.

The cable cores 102 accommodated in the distribution box 3009 extend from one side of the box 3009 (or an assembled portion of the cores 102, see the right-hand side of fig. 1) to the other side of the box 3009 (or a separated end of the cores 102, see the left-hand side of fig. 1) such that the cable cores 102 are spaced apart more and maintain a fixed distance therebetween. In the example of fig. 1, a first holding tool 301a holds the assembled part, a first holding tool 301b holds the intermediate part, a second holding tool 302 holds the separated end, and an intermediate holding tool 303 holds the cable core 102 between the first holding tools 301a and 301b, all holding the cable core 102.

The first holding tool 301a is provided with a ring-shaped portion in the middle. The outer periphery of the ring-shaped portion is equally spaced apart by three intermediate holding means 303, to which the sectors arranged between the intermediate holding means 303 are fixed. The first holding means 301a is disposed between the cores 102 such that the center of the annular portion is substantially at the center of the space surrounded by the three cable cores 102, and by disposing the cable cores 102 on the intermediate holding means 303, respectively, the cable cores 102 are spaced apart and held thereby. In the present embodiment, a sliding portion 304, which substantially touches the inner surface of the box 3009, is provided to the sector member, so that the first holding tool 301a can also move within the box 3009 with the expansion and contraction of the cable core 102. The first holding tool 301b is substantially similar in construction to the first holding tool 303a, except that the former has a larger diameter annular portion than the latter. The first holding means 301a and 301b are connected by intermediate holding means 303.

The second holding means 302 is substantially similar in structure to the first holding means 301 b. The first and second holding tools 301b and 302 are connected by a plurality of long bolts and held at a fixed distance from each other. Further, the first and second holding tools 301b and 302 each have an annular portion provided with a cylindrical insulating member 307 formed of FRP or the like insulating material and receiving the long bolt 305.

The intermediate holding tool 303 includes an elongated semi-circular arc-shaped or pipe-shaped (tubular) member 303a and a plurality of short semi-circular arc-shaped members 303b, the member 303a being fixed to a radially outer portion of the annular portion of the first holding tool 301a, 301b, the arc-shaped members 303b and the pipe-shaped member 303a being joined together to form a cylindrical body around the outer periphery of the cable core 102. In this embodiment, the components 303a and 303b are first arranged radially outside on the cable core 102 and then clamped to the radially outside on the cable core 102 by a band (not shown) or similar clamping means for fastening to hold the core. The intermediate holding tool 303 may be suitably provided with a through hole to assist in receiving the cable core 102 therein in contact with the refrigerant.

In the example of fig. 1, the connection electrodes are attached at separate ends of the cable core that are sufficiently separated. The connection electrodes can be easily and thus efficiently connected.

In the structure of fig. 1, the center electrode 4 and the fixing member 1d connecting the electrodes 1 are disposed offset as viewed in the longitudinal direction. Alternatively, as shown in fig. 3, the connection electrode 1 and the center electrode 4 may have a fixing member 1d and a connection portion 4b provided at a single position, respectively, and the fixing member 1d and the connection portion 4b may be connected in a Y-shaped pattern by the coupling member 2. More specifically, the fixing pieces 1d of each of the three connection electrodes 1 are respectively arranged radially outside the cable core 102, and the connection portions 4b connected to the rings 4a of the center electrode 4 may be arranged oppositely and connected by the coupling member 2. Alternatively, as shown in fig. 4, the center electrode may be dispensed with, the tabs 1a and 1b each having a fixing member 1d attached thereto or only one of them having two fixing members 1d attached thereto, such tabs 1a and 1b may be used to allow the respective fixing members 1d of the connecting electrode 1 and the other connecting electrode 1 to be connected by the coupling member 2 to provide a delta connection. In other words, the three coupling parts 2 may form three sides of a triangle whose apexes correspond to the three connection electrodes 1 arranged radially outward on the cable core 102, respectively.

The present terminal structure is suitable for constructing a terminal portion of a superconducting cable. Moreover, the present termination structure is also applicable to the construction of a superconducting cable line including the termination structure.

Although the invention has been described and illustrated in detail, it is understood that the foregoing is by way of example only and is not to be taken by way of limitation, the spirit and scope of the invention being limited only by the terms of the appended claims.

Claims (5)

1. A terminal structure of a superconducting cable (100) comprising a cable core (102) having superconducting layers (201, 203) and an electrically insulating layer (202), comprising a connection electrode (1) disposed on a radially outer portion of one superconducting shielding layer (203), the connection electrode (1) and the superconducting shielding layer (203) being connected by a low melting point solder; the melting point of the low-melting-point solder is 60 ℃ at minimum and 120 ℃ at maximum; wherein

The superconducting layers (201, 203) are superconducting conductor layers (201) and the superconducting shielding layers (203), the superconducting shielding layers (203) being located outermost of the superconducting layers (201, 203);

the electrically insulating layer (202) is disposed between the superconducting conductor layer (201) and the superconducting shielding layer (203);

the connection electrode (1) is provided to each of the cable cores (102) at a position radially outside the superconducting shielding layer (203); and is

The connection electrode (1) is connected to another connection electrode (1) by a conductive coupling member (2).

2. Termination structure for a superconducting cable (100) according to claim 1, wherein

The connection electrode (1) is thermally insulated from the electrically insulating layer (202).

3. Termination structure for a superconducting cable (100) according to claim 1, wherein

The connection electrode (1) has a ground line (3) mounted thereon.

4. A termination structure for a superconducting cable (100) according to claim 1, wherein said coupling member (2) is formed of a braided material.

5. A superconducting cable line comprising a termination structure of a superconducting cable (100) according to claim 1.