JP2018137071A - Superconductive cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a superconductive cable that suppresses a current accompanying arc discharge due to ground fault occurred in a cable core from branching to an inner tube to suppress the inner tube from being damaged.SOLUTION: A superconductive cable includes: a superconductive layer; a cable core having a grounding layer provided via an electric insulation layer on an outer periphery of the superconductive layer; an inner tube that houses the cable core and is filled with a liquid coolant; a heat insulation tube having an external tube forming a heat insulation layer on the outside of the inner tube; an arc resistant member that includes a fiber material in which a plurality of fibers are densely arranged, is interposed between the cable core and the inner tube and suppresses a current accompanying the arc discharge due to the ground fault generated at the cable core from branching to the inner tube; and an aperture suppression structure that suppresses formation of gaps between the fibers of the fiber material by volume expansion when a constituent member located in the neighborhood of the ground fault point of the cable core is vaporized.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a superconducting cable.

  In Patent Document 1, when an accident such as a ground fault occurs in the superconducting cable itself, an arc-resistant layer is formed on the outermost layer of the cable core in order to prevent the heat insulation tube from being damaged by arc discharge resulting from the accident. Is disclosed. This arc resistant layer is formed by winding a tape material made of a material excellent in arc resistance around the outer periphery of the cable core.

JP 2016-110988 A

  However, in the technique described in Patent Document 1, it has been found that a hole is opened in the inner pipe depending on the ground fault condition. In addition, it has been found that even when the number of arc-resistant layers is increased under the ground fault condition, it is not possible to significantly increase the time until a hole is opened in the inner tube or a hole is opened in the inner tube.

  Therefore, it is an object of the present invention to provide a superconducting cable that suppresses the shunting of the current due to the arc discharge caused by the ground fault generated in the cable core and suppresses the damage of the inner tube.

The superconducting cable according to the present disclosure is:
A cable core having a superconducting conductor layer and a ground layer provided on the outer periphery of the superconducting conductor layer via an electric insulating layer;
A heat insulating tube having an inner tube that houses the cable core and is filled with a liquid refrigerant, and an outer tube that forms a heat insulating layer outside the inner tube;
It is composed of a fiber material in which a plurality of fibers are densely arranged, and is interposed between the cable core and the inner tube, and a current accompanying an arc discharge caused by a ground fault generated in the cable core is shunted to the inner tube. An arc-resistant member that suppresses this,
Fibers of the fiber material by volume expansion when the arc-proof member and a component member provided near at least one of the arc-proof member and the cable core and positioned near the ground fault point of the cable core are vaporized. And an opening suppression structure that suppresses the formation of a gap therebetween.

  The superconducting cable suppresses the current accompanying the arc discharge caused by the ground fault generated in the cable core from being shunted to the inner tube, and suppresses damage to the inner tube.

FIG. 2 is a transverse cross-sectional view illustrating an outline of the superconducting cable of the first embodiment. It is a cross-sectional view which shows the outline of the superconducting cable of Embodiment 2. 6 is a cross-sectional view illustrating an outline of a superconducting cable of Modification Example 1. FIG. It is a cross-sectional view showing an outline of the superconducting cable of Embodiment 3. It is a cross-sectional view showing an outline of the superconducting cable of the fourth embodiment. FIG. 10 is a transverse cross-sectional view illustrating an outline of a superconducting cable according to a fifth embodiment.

[Description of Embodiment of the Present Invention]
Arc discharge occurs from a superconducting conductor layer having a high potential toward a grounding layer having a zero potential when grounded or other accident occurs in the cable core and electrical breakdown occurs. When arc discharge occurs, constituent members (insulating paper, conductor, liquid refrigerant, etc.) located near the ground fault point of the cable core are vaporized. As a phenomenon that occurs when the above constituent members are vaporized, the present inventors, when the arc-resistant layer is wound around the cable core, surrounds the internal pressure of the arc-resistant layer (the arc-resistant layer) by volume expansion during vaporization. We focused on the fact that the pressure on the cable core side rises more instantaneously. The arc-resistant layer (arc-resistant member) is generally composed of a fiber material in which a plurality of fibers are densely arranged like a woven fabric. Therefore, when the internal pressure of the arc-resistant member rises, the arc-resistant member receives the internal pressure, so that a gap (opening) is formed between the fibers of the fiber material constituting the arc-resistant member, and vaporized gas is released from the gap. At the same time, the current accompanying the arc discharge flows through the inner tube. Then, the structure which suppresses that a clearance gap is formed in the fiber material which comprises an arc-resistant member by the internal pressure rise of an arc-resistant member was examined, and it came to complete this invention. The contents of the embodiments of the present invention will be listed and described below.

(1) A superconducting cable according to an embodiment of the present invention,
A cable core having a superconducting conductor layer and a ground layer provided on the outer periphery of the superconducting conductor layer via an electric insulating layer;
A heat insulating tube having an inner tube that houses the cable core and is filled with a liquid refrigerant, and an outer tube that forms a heat insulating layer outside the inner tube;
It is composed of a fiber material in which a plurality of fibers are densely arranged, and is interposed between the cable core and the inner tube, and a current accompanying an arc discharge caused by a ground fault generated in the cable core is shunted to the inner tube. An arc-resistant member that suppresses this,
Fibers of the fiber material by volume expansion when the arc-proof member and a component member provided near at least one of the arc-proof member and the cable core and positioned near the ground fault point of the cable core are vaporized. And an opening suppression structure that suppresses the formation of a gap therebetween.

  By providing the structure to suppress opening, the internal pressure of the arc-resistant member (pressure on the cable core side relative to the arc-resistant member) increases due to volume expansion when the component near the ground fault point of the cable core is vaporized by arc discharge. Even if it does, it can suppress that a clearance gap is formed in the constituent material of an arc-resistant member. Therefore, the superconducting cable can suppress the current accompanying the arc discharge caused by the ground fault generated in the cable core from being shunted to the inner tube, and can suppress damage such as opening of a hole in the inner tube.

  (2) As one form of the superconducting cable, the opening prevention structure is configured such that the arc-resistant member surrounds the outer periphery of the cable core and expands by volume expansion when the component member is vaporized. For example, it may be provided with a surplus portion that is in close contact with the inner surface.

  By providing the arc-resistant member with an extra length portion as the mesh opening suppression structure, the arc-resistant member can spread outward due to volume expansion when the constituent members near the ground fault point of the cable core are vaporized. The surplus portion has a spread length (a length formed by slack or overlap) that allows the arc-resistant member to be in close contact with the inner surface of the inner tube. When the arc resistant member is in close contact with the inner tube, the internal pressure of the arc resistant member can be received by the inner tube through the arc resistant member. Therefore, the arc resistant member can suppress the formation of a gap in the constituent material of the arc resistant member by the constituent material being crushed toward the inner tube by the internal pressure. Note that the arc-resistant member is not particularly limited as long as it can be brought into close contact with the inner surface of the inner tube by volume expansion when the constituent members are vaporized.

  (3) As one form of the said superconducting cable, the said mesh opening suppression structure is provided with the spacer which forms a space between the surface of the ground fault point vicinity of the said cable core, and the said arc-resistant member.

  By providing the spacer as the mesh opening restraining structure, it is possible to form a space in which the vaporized gas can flow when the component near the ground fault point of the cable core is vaporized. By allowing the vaporized gas to flow, the pressure difference between the inside and outside of the arc-resistant member (the difference between the pressure on the cable core side and the pressure on the inner tube side of the arc-resistant member) can be reduced. Therefore, even if the internal pressure of the arc resistant member rises momentarily, the pressure received by the arc resistant member can be reduced, so that formation of a gap in the constituent material of the arc resistant member can be suppressed.

  (4) As one form of the superconducting cable, the opening prevention structure includes the arc-resistant member having an opening through which the vaporized gas when the constituent member is vaporized flows to the inner tube side. .

  By providing the arc-resistant member with an opening as an opening suppression structure, a continuous space can be formed on the cable core side and the inner tube side with the arc-resistant member interposed therebetween. By this space, the vaporized gas when the component near the ground fault point of the cable core is vaporized can flow to the inner tube side. By allowing the vaporized gas to flow to the inner tube side, the pressure difference between the inside and outside of the arc-resistant member can be reduced. Therefore, even if the internal pressure of the arc resistant member rises momentarily, the pressure received by the arc resistant member can be reduced, so that formation of a gap in the constituent material of the arc resistant member can be suppressed.

  (5) As one form of the superconducting cable, the superconducting cable may be a single core cable having one cable core.

  As an opening suppression structure, the form provided with the extra length part in the arc-resistant member and the form provided with the spacer can be easily configured regardless of the number of cable cores, and can be suitably used for a single-core cable.

  (6) As one form of the superconducting cable, the superconducting cable may be a multi-core cable having a plurality of the cable cores.

  As an opening suppression structure, an arc-resistant member having an extra length or an opening or a spacer can be easily configured regardless of the number of cable cores and can be suitably used for a multi-core cable. .

  (7) As one form of the superconducting cable, which is a multi-core cable, an electric current caused by an arc discharge caused by a ground fault occurring in one of the cable cores is interposed between the cable cores facing each other. It is mentioned to provide an intervening arc-resistant member that suppresses diversion.

  In the case of a multi-core cable, when one of the cable cores breaks down and arc discharge occurs, the current accompanying the arc discharge is shunted to the other cable cores facing each other, and the cable cores are short-circuited. There is a fear. The superconducting cable includes an intervening arc resistant member between the opposing cable cores, so that the current accompanying the arc discharge in one cable core can be prevented from being diverted to the other cable core. Therefore, the superconducting cable can prevent the opposing cores from being short-circuited by arc discharge from one of the plurality of cable cores.

  An intervening arc-resistant member that suppresses the current accompanying arc discharge caused by a ground fault generated in a certain cable core from being shunted to another cable core is provided independently of the arc-resistant member that suppresses the shunting to the inner pipe. And increase in the size of the cable can be suppressed. For example, if the thickness of the arc-resistant member necessary to suppress the shunting of current due to arc discharge to the inner tube is t, and the arc-resistant member is wound directly above the cable core, it is interposed between the cable cores. The thickness of the arc-proof portion to be applied is 2 × t. By making the arc-resistant member that suppresses the shunt to the inner pipe and the intervening arc-proof member that suppresses the shunt to the other cable core as separate members, the thickness of each arc-resistant member can be t, Both the diversions can be suppressed, and the thickness between the cable cores can be set to t, so that an increase in the size of the cable can be suppressed.

  (8) As one form of the said superconducting cable, it is mentioned that the said arc-resistant member is comprised with the fiber material containing at least one of an aramid and a silica.

  A fiber material containing aramid or silica is excellent in arc resistance. Therefore, when the arc resistant member is made of the above-mentioned material, it is difficult to divert the current accompanying the arc discharge due to the ground fault generated in the cable core to the inner tube, and the thickness of the arc resistant member can be easily reduced.

  (9) As one form of the superconducting cable, it may be applied to a resistance grounding system.

  When the power transmission system is a resistance grounding system (in Japan, 154 kV or less), the ground fault current is 1 kA class, and the superconducting cable can suitably suppress the shunting of the ground fault current to the inner pipe, and damage the inner pipe. Can be suppressed.

[Details of the embodiment of the present invention]
Hereinafter, specific examples of embodiments of the present invention will be described with reference to the drawings. The same code | symbol in a figure shows the same name thing.

<Embodiment 1>
〔overall structure〕
With reference to FIG. 1, the superconducting cable 1A of Embodiment 1 is demonstrated. As shown in FIG. 1, the superconducting cable 1 </ b> A includes a plurality of cable cores 10 having a superconducting conductor layer 12, an electrical insulating layer 13, and a ground layer 14, and a heat insulating tube 20 that houses the plurality of cable cores 10. It is a batch cable. In this example, it is a three-core collective cable configured by twisting three cable cores 10a, 10b, and 10c. Superconducting cable 1A is laid to construct a power transmission path.

  Each cable core 10 has the same configuration, and includes a former 11, a superconducting conductor layer 12, an electrical insulating layer 13, a ground layer 14, and a protective layer 15 in order from the center. The heat insulating tube 20 is a double structure vacuum heat insulating tube including an inner tube 21 and an outer tube 22. The superconducting cable 1A is a low-temperature insulating cable in which both the superconducting conductor layer 12 and the electrical insulating layer 13 are accommodated in a heat insulating tube 20 and cooled by a liquid refrigerant L such as liquid nitrogen. The basic configuration of the superconducting cable 1A is similar to a conventional superconducting cable.

  The superconducting cable 1A according to the first embodiment has an arc-resistant member 30A that collectively surrounds the outer periphery of the three cable cores 10a, 10b, and 10c, and an opening suppression structure 40 that maintains the arc resistance of the arc-resistant member 30A. One of the features is that The arc-resistant member 30 </ b> A is interposed between the cable core 10 and the inner tube 21, and suppresses the current accompanying the arc discharge caused by the ground fault generated in the cable core 10 from being diverted to the inner tube 21. The arc-resistant member 30A is made of a fiber material in which a plurality of fibers are densely arranged. When the arc discharge occurs in the cable core 10, constituent members (the constituent members of the cable core 10 such as the electrical insulating layer 13 and the liquid refrigerant L) that are located near the ground fault point of the cable core 10 are vaporized. The opening suppression structure 40 suppresses the formation of a gap between fibers of the fiber material constituting the arc-resistant member 30 </ b> A due to volume expansion when these constituent members are vaporized.

  In addition, the superconducting cable 1 </ b> A of the first embodiment is characterized in that it includes an intervening arc-resistant member 50 interposed between the cable cores 10. The intervening arc-resistant member 50 prevents the current accompanying the arc discharge caused by the ground fault generated in one of the cable cores 10, 10 facing the current from being shunted to the other cable core 10.

  Hereinafter, each configuration will be described in detail.

(Cable core)
Former The former 11 is a support member that supports the superconducting conductor layer 12. Specific examples include solid bodies such as a hollow body such as a tube material, a twisted wire obtained by twisting a plurality of strands, and a twisted product obtained by further twisting a plurality of twisted wires. Main constituent materials include normal conducting materials such as copper, aluminum, and alloys thereof. Examples of the element wire include a covered wire in which a metal conductor wire is covered with an insulating coating.

-Superconducting conductor layer The superconducting conductor layer 12 includes a wire layer formed by winding a plurality of superconducting wires around the outer periphery of the former 11. Examples of the superconducting wire include a tape-shaped wire such as an oxide-based silver sheathed wire containing bismuth such as Bi2223 and an oxide-based thin film wire containing a rare earth element such as RE123. The number of wires used, the number of wires used, and the like can be selected according to a predetermined amount of power. The wire layer can be either a multilayer or a single layer. In the case of multiple layers, an interlayer insulating layer (not shown) in which insulating paper or the like is wound can be provided. Further, a cushion layer (not shown) may be interposed between the former 11 and the superconducting conductor layer 12. The cushion layer can be formed by winding kraft paper or the like.

-Electrical insulation layer The electrical insulation layer 13 is interposed between the superconducting conductor layer 12 and the ground layer 14 disposed outside thereof, and ensures electrical insulation between them. Examples of the electrical insulating layer 13 include a wound layer formed by winding insulating paper such as kraft paper or semi-synthetic paper including resin and kraft paper around the outer periphery of the superconducting conductor layer 12. Semi-synthetic paper includes polypropylene resin and kraft paper, such as PPLP (Polypropylene Laminated Paper) (registered trademark). A semiconductive layer (not shown) can be provided inside and outside the electrical insulating layer 13.

Grounding layer The grounding layer 14 is a conductive portion that is provided on the outer periphery of the superconducting conductor layer 12 via the electrical insulating layer 13 and takes a ground potential. Examples of the ground layer 14 include a winding layer formed by appropriately winding the above-described superconducting wire, a wire made of a normal conducting material such as copper, a tape material, a braided material, and the like. When the ground layer 14 is formed of a superconducting wire, the ground layer 14 can be used as a superconducting shield layer in AC power transmission.

  A grounding layer 14 having an outer superconducting conductor layer formed of a superconducting wire and a normal conducting conductor layer formed of a normal conducting material can be provided on the outer periphery of the electrical insulating layer 13. By providing a normal conductor layer in addition to the outer superconductor layer, when the outer superconductor layer is quenched by an accident current during an accident such as a short circuit or ground fault, the fault current is diverted to the normal conductor layer. Temperature increase due to a large accidental current flowing through the outer superconducting conductor layer can be suppressed. An interlayer insulating layer can be provided between the outer superconducting layer and the ground layer 14 of normal conducting material.

Protective layer The protective layer 15 is disposed on the outermost periphery of the cable core 10 and is mainly used for mechanical protection of members disposed inside the cable core 10 and ensuring electrical insulation between the grounding layer 14 and the heat insulating tube 20. As provided. Examples of the protective layer 15 include an insulating paper tape such as kraft paper, a semi-synthetic insulating paper in which kraft paper and plastic are combined, for example, PPLP wound in a tape shape.

[Insulated pipe]
The heat insulating tube 20 is a dual structure tube having an inner tube 21 and an outer tube 22 provided on the outer periphery of the inner tube 21, and a vacuum in which a vacuum heat insulating layer is formed between the inner tube 21 and the outer tube 22. It is an insulated pipe. The inner space of the inner tube 21 is a storage space for the cable core 10 and is filled with a liquid refrigerant L for maintaining the superconducting state of the superconducting conductor layer 12 and the outer superconducting layer (the refrigerant flow path). It is. The inner tube 21 and the outer tube 22 are metal tubes made of stainless steel or the like, and are excellent in flexibility when used as a corrugated tube (this example) or bellows tube, and have a small surface area and excellent heat insulating properties as a flat tube. The pressure loss of the refrigerant L can be reduced. When a heat insulating material (not shown) such as a super insulation is provided between the inner tube 21 and the outer tube 22, it has higher heat insulating properties.

  On the outer side of the outer tube 22 of the heat insulating tube 20, an anticorrosion layer 24 made of an anticorrosion material such as vinyl or polyethylene is provided.

(Arc-resistant members)
-Material The arc-resistant member 30 </ b> A suppresses the current that accompanies arc discharge caused by the ground fault generated in the cable core 10 from being diverted to the inner tube 21. The arc resistant member 30A has arc resistance that maintains insulation performance when exposed to arc discharge, that is, tracking resistance or heat resistance. The arc-resistant member 30A is made of a fiber material in which a plurality of fibers are densely arranged. The constituent material of the arc resistant member 30A preferably includes a high arc resistant material having excellent arc resistance and tracking resistance.

  Examples of the high arc resistant material include fibers (organic fibers) made of a resin (organic material) such as aramid fibers, and fibers (inorganic fibers) made of an inorganic material such as carbon fibers, glass fibers, and ceramic fibers. In particular, high-performance and high-performance fibers that have excellent mechanical properties such as strength and rigidity, and excellent heat resistance and flame retardancy can be mentioned. High-performance and high-performance fibers are called high-strength fibers and super fibers that are excellent in strength, especially high-strength and high-modulus fibers that are excellent in strength and rigidity, especially high-heat-resistant fibers that are excellent in heat resistance and flame resistance. Etc.

Examples of the high-strength fiber, high-strength / high-modulus fiber include para-aramid fiber, ultrahigh molecular weight polyethylene fiber, polyarylate fiber, polyparaphenylenebenzobisoxazal (PBO) fiber, and carbon fiber. Examples of the high heat resistant fiber include meta-aramid fiber, PPS fiber, PI fiber, and fluorine fiber. Examples of non-combustible fibers include glass fibers and ceramic fibers. A typical example of the constituent material of the glass fiber is silica (SiO ₂ ). Examples of the ceramic constituting the ceramic fiber include metal oxides such as aluminum oxide (alumina), boron oxide, and other metal carbides and metal nitrides. Examples thereof include fibers containing silica and ceramics, for example, ceramic fibers containing silica and alumina, and fibers containing a plurality of types of ceramics, for example, ceramic fibers containing silica, boron oxide, and alumina. Glass fiber and ceramic fiber can form an arc resistant member that is more excellent in arc resistance. Therefore, the thickness etc. of arc-resistant member 30A can be made thinner. Aramid fibers can form an arc-resistant layer that is also excellent in strength. Therefore, it is preferable that the constituent material of the arc resistant member 30A includes at least one high arc resistant material of glass fiber, ceramic fiber, and aramid fiber. At least one of glass fiber and ceramic fiber and an aramid fiber can be included.

-Form The arc-resistant member 30A is arranged by covering the outer periphery of an assembly in which a plurality of cable cores 10 are appropriately twisted with a tape material or a sheet material in which the above-described fibers are densely arranged like a woven fabric or the like. The arc-resistant member 30 </ b> A is disposed so as to be interposed between the cable core 10 and the inner tube 21 in an area where at least a current due to a ground fault generated in the cable core 10 may be diverted to the inner tube 21. The In this example, the arc-resistant member 30A is a cylindrical member that surrounds the aggregate of the three cable cores 10a, 10b, and 10c over the entire circumference and the entire length, and is normally arranged in a slack state (see FIG. 1 is provided with a surplus portion 42A that expands outward due to volume expansion when a component located near the ground fault point of the cable core 10 is vaporized (lower view in FIG. 1). The extra length portion 42A will be described in detail in an opening suppression structure 40 described later.

  As the arc resistant member 30A is thicker, it is easier to improve the arc resistance. However, when the thickness is too thick, the superconducting cable 1A is increased in size. Although it depends on the material of the arc-resistant member 30A and the like, the thickness of the arc-resistant member 30A is preferably thin, and may be 20 mm or less, further 10 mm or less, and 5 mm or less. Specifications such as the thickness of the arc-resistant member 30A can be selected as appropriate.

(Opening suppression structure)
The opening suppression structure 40 is a volume expansion when a component located near the ground fault generated in the cable core 10 is vaporized, and there is a gap (opening) between fibers of the fiber material constituting the arc-resistant member 30A. Suppresses formation. The opening suppression structure 40 is configured by an extra length portion 42A (upper view in FIG. 1) provided in the arc resistant member 30A. The surplus length portion 42A is a volume expansion when a component located in the vicinity of the ground fault point of the cable core 10 is vaporized, and has a spreading length (sagging) that allows the arc-resistant member 30A to be in close contact with the inner surface of the inner tube 21. . The perimeter of arc-resistant member 30A is longer than the perimeter of the envelopes of the three cable cores 10a, 10b, 10c. The extra length portion 42A referred to here is a portion having a length obtained by subtracting a length corresponding to the circumferential length of the envelope of the cable core from the circumferential length of the arc-resistant member 30A. In the upper diagram of FIG. 1, for convenience of explanation, an extra length portion 42 </ b> A is attached to a portion that crosses between adjacent cable cores 10.

  By providing the arc-resistant member 30A with the extra length portion 42A, the arc-resistant member 30A comes into close contact with the inner surface of the inner tube 21 when the cable core 10 is grounded, as shown in the lower diagram of FIG. In this state, the inner pressure of the arc-resistant member 30A (pressure on the cable core 10 side with respect to the arc-resistant member 30A) increased by the volume expansion when the constituent members are vaporized is caused by the inner tube 21 via the arc-resistant member 30A. Can receive. By receiving the internal pressure with the internal pipe 21, the arc resistant member 30A can suppress the constituent material from being crushed by the internal pressure toward the internal pipe 21 and forming a gap.

  The circumferential length of the arc-resistant member 30A is preferably equal to or greater than the circumferential length of the inner surface of the inner tube 21. By doing so, the arc resistant member 30 </ b> A can be in close contact with the entire surface of the inner tube 21, and a portion that is not in close contact can be prevented from being formed. When the circumference of the arc resistant member 30A is longer than the circumference of the inner surface of the inner tube 21, the overlap portion 440 (the lower diagram in FIG. 1) is formed with the arc resistant member 30A in close contact with the inner surface of the inner tube 21. The

  The arc-resistant member 30A may be in close contact with the inner surface of the inner tube 21 when the cable core 10 is grounded, and may be disposed in a slack state as described above (see FIG. 1). The upper figure) may be arranged in a state of being substantially in contact with the inner surface of the inner tube 21. In addition, the arc resistant member 30A may be arranged in close contact with the inner surface of the inner tube 21 from the time of manufacturing the superconducting cable 1A.

[Intermediate arc-resistant members]
The intervening arc-resistant member 50 includes a cable core 10b, in which when a certain cable core 10a among the three cable cores 10a, 10b, 10c breaks down and an arc discharge occurs, a current associated with the arc discharge is opposed. The diversion to 10c is suppressed. The intervening arc resistant member 50 is made of the same material as the arc resistant member 30A described above.

  As shown in FIG. 1, the intervening arc resistant member 50 is disposed between the cable cores 10a, 10b, and 10c. Specifically, the intervening arc-resistant member 50a is disposed between the cable cores 10a and 10b, and the shunt current of the arc current from the cable core 10a to the cable core 10b and the shunt current of the arc current from the cable core 10b to the cable core 10a. Suppress. The intervening arc-resistant member 50b is disposed between the cable cores 10b and 10c and suppresses the shunting of the arc current from the cable core 10b to the cable core 10c and the shunting of the arc current from the cable core 10c to the cable core 10b. The intervening arc-resistant member 50c is disposed between the cable cores 10c and 10a and suppresses the shunting of the arc current from the cable core 10c to the cable core 10a and the shunting of the arc current from the cable core 10a to the cable core 10c. In this example, the three intervening arc resistant members 50a, 50b, 50c are configured independently without mechanically connecting each end. The three intervening arc-resistant members 50a, 50b, 50c may all have the same shape and material, or the shapes and materials may be different as long as the arc current diversion between the cable cores 10a, 10b, 10c can be suppressed. Also good.

〔Production method〕
The above-described superconducting cable 1A is typically produced in a factory or the like in an assembly of cable cores 10 having intervening arc-resistant members 50, and the aggregate of cable cores 10 is stored in a cylindrical arc-resistant member 30A. At the same time, the assembly of the cable core 10 provided with the arc-resistant member 30 </ b> A can be manufactured by being housed in the heat insulating tube 20. For example, when the cable cores 10a, 10b, and 10c are twisted together, the aggregate of the cable cores 10 that include the intervening arc-resistant members 50 includes tape-shaped intervening arc-resistant members 50a and 50c, respectively, between the cable cores 10a, 10b, and 10c. It can be easily manufactured by twisting together while interposing 50b and 50c. When the aggregate of the cable cores 10 is stored in the cylindrical arc-resistant member 30A, it is preferable that the extra-length portion 42A of the arc-resistant member 30A is attached to the cable core 10. In addition, after the assembly (an assembly of the cable core 10 including the intervening arc-resistant member 50) manufactured in a factory or the like is transported to the installation site and the heat insulation pipe 20 is installed in the installation path, the assembly of the cable core 10 is formed into a cylinder. The superconducting cable 1 </ b> A can be manufactured by housing the cable core 10 provided with the arc-resistant member 30 </ b> A in the heat insulating tube 20.

〔effect〕
The superconducting cable 1A according to the first embodiment includes a cylindrical arc-resistant member 30A that surrounds the aggregate of the three cable cores 10a, 10b, and 10c over the entire circumference and the entire length, so that which cable core 10a, 10b, Even if a ground fault occurs at 10c, it is possible to suppress the current accompanying arc discharge caused by the ground fault from being shunted to the inner tube 21. In particular, the superconducting cable 1A is provided with the extra length portion 42A as the opening restraining structure 40 in the arc-resistant member 30A, so that the volume expansion when the component near the ground fault point of the cable core is vaporized by arc discharge, The arc-resistant member 30 </ b> A spreads outward and can adhere to the inner surface of the inner tube 21. Since the arc-resistant member 30A is in close contact with the inner tube 21, even if the internal pressure of the arc-resistant member 30A is increased due to the volume expansion, the inner pressure can be received by the inner tube 21 via the arc-resistant member 30A. It is possible to suppress the formation of gaps (openings) in the constituent material of the arc resistant member 30A. Therefore, while the arc discharge continues, the fibers of the constituent material of the arc resistant member 30 </ b> A can be kept dense, the shunting of the arc current to the inner tube 21 can be suppressed, and damage such as opening of a hole in the inner tube 21 can be suppressed.

  In addition, the superconducting cable 1A according to the first embodiment includes the arc-resistant members 50a, 50b, and 50c interposed between the three cable cores 10a, 10b, and 10c. When it occurs, it is possible to suppress the current accompanying the arc discharge from being shunted to the opposing cable cores 10b and 10c. Therefore, the superconducting cable 1A can prevent a short circuit from occurring between adjacent cable cores due to the arc discharge. That is, it is possible to prevent a transition from a ground fault accident to a short-circuit accident.

<Embodiment 2>
In the second embodiment, as shown in FIG. 2, the arc-resistant member 30B is a sheet-like member that wraps and surrounds an assembly of three cable cores 10a, 10b, and 10c over the entire circumference and the entire length. The cable 1B will be described. Superconducting cable 1 </ b> B includes an arc-resistant member 30 </ b> B having a surplus length portion 42 </ b> B as an opening suppression structure 40. The superconducting cable 1B is different from the superconducting cable 1A of the first embodiment in that the arc-resistant member 30B is a sheet-like member having both ends in the circumferential direction.

  The arc-resistant member 30B is normally arranged in a state where the end regions of the sheet-like member overlap each other (upper view in FIG. 2), and the volume expansion when the constituent member located near the ground fault point of the cable core 10 is vaporized. In FIG. 2, an extra length portion 42 </ b> B (opening suppression structure 40) is provided that spreads outward by sliding the overlapping portion (the lower diagram in FIG. 2). The surplus portion 42B is a volume expansion when a constituent member located in the vicinity of the ground fault point of the cable core 10 is vaporized, and has a spreading length (overlap) that allows the arc-resistant member 30B to adhere to the inner surface of the inner tube 21. . If the arc-resistant member 30B can be brought into close contact with the inner surface of the inner tube 21 due to the above volume expansion, the surplus portion 42B may have a slack portion (corresponding to the surplus length portion 42A in FIG. 1) in addition to the overlapping portion. it can.

  The arc-resistant member 30B is not connected end portions. Therefore, even if the surplus length portion 42B is swelled by the above volume expansion and the overlapping portion of the end region slides and the arc-resistant member 30B spreads outward, the extra-length portion 42B is spaced between the end portions along the longitudinal direction of the arc-resistant member 30B. It is configured to overlap so that no gap is formed. Specifically, the surplus length portion 42B has such a length that the overlap portion 440 (the lower diagram in FIG. 2) is formed in a state where the arc-resistant member 30B is in close contact with the inner surface of the inner tube 21. By doing so, the arc-resistant member 30B can be in close contact with the entire surface of the inner tube 21, and a portion that is not covered with the arc-resistant member 30B can be prevented from being formed on the inner tube 21.

  The superconducting cable 1B is typically produced at a factory or the like by producing an assembly of cable cores 10 including intervening arc-resistant members 50, and wrapping the assembly of cable cores 10 with a sheet-like arc-resistant member 30B. The assembly of the cable core 10 provided with the arc-resistant member 30B can be manufactured by being housed in the heat insulating tube 20. When the aggregate of the cable cores 10 is wrapped with the sheet-like arc resistant member 30B, it is preferable to lengthen the overlapping portion of the extra length portion 42B so that the arc resistant member 30B contacts the cable core 10. In addition, an assembly (an assembly of the cable core 10 including the intervening arc-resistant member 50) manufactured at a factory or the like is transported to the installation site, and the insulation pipe 20 is installed in the installation path, and then the assembly of the cable core 10 is a sheet. The superconducting cable 1B can also be manufactured by housing the assembly of the cable core 10 provided with the arc-resistant member 30B in the heat insulating tube 20 while wrapping it in the arc-shaped arc-resistant member 30B.

<Modification 1>
As another form of the intervening arc-resistant member 50, as shown in FIG. 3, a superconducting cable 1C in which three intervening arc-resistant members 50a, 50b, and 50c are individually arranged in the cable cores 10a, 10b, and 10c, respectively. Good. Specifically, the intervening arc-resistant member 50a is a belt-like member disposed along the longitudinal direction of the cable core 10a, and covers the surface of the cable core 10a that faces the cable core 10b and the cable core 10c. Is arranged. The intervening arc resistant member 50b is a belt-like member disposed along the longitudinal direction of the cable core 10b, and is disposed so as to cover the surface of the cable core 10b that faces the cable core 10a and the cable core 10c. The intervening arc resistant member 50c is a band-shaped member disposed along the longitudinal direction of the cable core 10c, and is disposed so as to cover the cable core 10b and the surface facing the cable core 10a in the cable core 10c. That is, in this example, there is a portion where the intervening arc-resistant member 50 is disposed in two layers between the adjacent cable cores 10. The shunting of the arc current in the adjacent cable core 10 can be suppressed by combining the intervening arc-resistant members 50 respectively arranged in the adjacent cable core 10. An optical unit such as an optical fiber for temperature measurement can be arranged in a space having a triangular cross section surrounded by the intervening arc resistant members 50a, 50b, 50c.

<Embodiment 3>
In the third embodiment, as shown in FIG. 4, the arc-resistant member 30D is a cylindrical member that surrounds the aggregate of the three cable cores 10a, 10b, and 10c over the entire circumference and the entire length. A superconducting cable 1D whose length does not substantially change between the normal time and the ground fault of the cable core 10 will be described. The superconducting cable 1 </ b> D includes an opening 44 in the arc-resistant member 30 </ b> D as the opening suppression structure 40. The superconducting cable 1 </ b> D is that the arc-resistant member 30 </ b> D is a cylindrical member whose circumference does not change, and that the arc-resistant member 30 </ b> D is provided with an opening 44 as the opening restraining structure 40. And different.

  The arc-resistant member 30D is composed of a cylindrical member whose circumferential length does not substantially change before and after volume expansion when the structural member located near the ground fault point of the cable core 10 is vaporized. Are provided with openings 44 at appropriate positions. Since the cable core 10 is formed by being twisted together, the openings 44 are formed in a dispersed manner in the spiral direction along the twisted groove of the cable core 10. In FIG. 4, three openings 44a, 44b, and 44c are provided in the circumferential direction, and the arc-resistant member 30D appears to be divided, but the openings 44a, 44b, and 44c are formed to be dispersed in the spiral direction. The arc-resistant member 30D is one member that is continuous in the longitudinal direction.

  The openings 44a, 44b, and 44c are formed in regions where currents associated with ground faults generated in the cable core 10 are difficult to divert to the inner tube 21, respectively. Specifically, it is formed at a position facing a twisted groove formed between adjacent cable cores 10a, 10b, 10c. In this example, in the envelopes of the three cable cores 10a, 10b, 10c, an opening 44 is formed in the other region so that the vicinity of the region in contact with each cable core 10 is covered with the arc-resistant member 30D. Yes. The shape of the opening 44 can be selected as appropriate, such as a circle, an ellipse, or a polygon. The size of the opening 44 can be selected as appropriate so that the pressure difference between the inside and outside of the arc-resistant member 30D can be reduced, and the arc-resistant member 30D can have a strength that is difficult to be damaged during manufacture or use.

  By providing the arc-resistant member 30D with the openings 40a, 40b, and 40c, a continuous space can be formed on the cable core 10 side and the inner tube 21 side with the arc-resistant member 30D interposed therebetween. Since the openings 40a, 40b, and 40c are formed on substantially triangular sides enclosing the three cable cores 10a, 10b, and 10c, a ground fault occurs in which cable core 10a, 10b, and 10c. In addition, the vaporized gas when the component near the ground fault point of the cable core is vaporized can quickly flow to the inner tube 21 side. By allowing the vaporized gas to flow to the inner tube 21 side, the pressure difference between the inside and outside of the arc resistant member 30D can be reduced, and the pressure received by the arc resistant member 30D can be reduced. Opening) can be suppressed. Therefore, while the arc discharge continues, the fibers of the constituent material of the arc resistant member 30 </ b> D can be kept dense, the shunting of the arc current to the inner tube 21 can be suppressed, and damage such as opening of a hole in the inner tube 21 can be suppressed.

  The superconducting cable 1D is typically produced in the same manner as in the first embodiment in a factory or the like by producing an assembly of the cable cores 10 including the intervening arc-resistant members 50, and the assembly of the cable cores 10 is formed into a cylindrical arc-proofing. While being housed in the member 30D, the assembly of the cable core 10 provided with the arc-resistant member 30D can be housed in the heat insulating tube 20. However, since the cable core 10 is twisted together, the opening 44 is also formed according to the twist of the cable core 10, and when the assembly of the cable cores 10 is housed in the arc resistant member 30 </ b> D, the cable core 10 is This is performed so that the opening 44 is not disposed in a region that may come into contact with the inner tube 21.

<Embodiment 4>
In the fourth embodiment, as shown in FIG. 5, the arc-resistant member 30E is a tape-like member that winds the aggregate of the three cable cores 10a, 10b, and 10c over the entire circumference and the entire length. A superconducting cable 1E including a spacer 46, which is a member different from the arc-resistant member 30E, will be described as the opening suppression structure 40. The spacer 46 forms a space 460 between the surface of the cable core 10 near the ground fault point and the arc resistant member 30E. That is, the arc resistant member 30 </ b> E is configured to be wound on the spacer 46. The superconducting cable 1E is different from the superconducting cable 1A of the first embodiment in that the arc-resistant member 30E is a tape-like member and that the spacer 46 is provided as the opening suppression structure 40. In FIG. 5, interposition members (see FIG. 1 and the like) interposed between the cable cores 10 are omitted.

  The spacer 46 is for forming a space 460 between the surface of the cable core 10 near the ground fault point and the arc-resistant member 30E disposed on the spacer 46. Therefore, the size of the spacer 46 may be appropriately selected so that the desired space 460 is obtained. For example, the thickness is 1 mm or more and 6 mm or less, and further, 2 mm or more and 4 mm or less. The spacer 46 is made of, for example, silicon resin that hardly changes in quality due to immersion in the coolant, and can be arranged by being spirally wound around the outer periphery of the cable core 10. The spacer 46 may be wound or vertically attached to the outer periphery of the cable core 10 using, for example, a ladder-like member in which a plurality of bar members are held in parallel by a connecting member. The spacer 46 may further be provided with a pressing tape for fixing the spirally wound or vertically attached outer periphery of the cable core 10, and the pressing tape is made of a member similar to the arc-resistant member 30E. Also good. In this example, in each of the cable cores 10a, 10b, and 10c, the spacer 46 is formed by spirally winding a long material having a semicircular cross section at a position that divides the outer periphery into four equal parts.

  The arc resistant member 30 </ b> E is formed of a wound layer that winds a tape-shaped member on the spacer 46. In this example, the arc resistant member 30E has a shape substantially similar to the envelope shape of the three cable cores 10a, 10b, and 10c when the superconducting cable 1E is viewed in a cross section (see FIG. 5). By winding the arc-resistant member 30E on the spacer 46, the three cable cores 10a, 10b, 10c can be made into one aggregate and easy to handle. For example, the winding layer may be configured such that the cable core 10 is not exposed by covering the tape-like member with a plurality of layers by winding the tape-like member and covering the inner layer gap with an outer-layer tape-like member. It is possible to make a structure by wrapping. The arc-resistant member 30E may be a cylindrical member having an extra length as in the first embodiment or a sheet-like member having an extra length as in the second embodiment, and an opening as in the third embodiment. May be provided.

  By providing the spacer 46 as an opening suppression structure, a space 460 can be formed between the surface near the ground fault point of the cable core 10 and the arc resistant member 30E disposed on the spacer 46, and the ground of the cable core 10 can be formed. When the constituent member near the entanglement point is vaporized, the vaporized gas can flow through the space 460. By allowing the vaporized gas to flow, the pressure difference between the inside and outside of the arc resistant member 30E can be reduced, and the pressure received by the arc resistant member 30E can be reduced, so that a gap (opening) is formed in the constituent material of the arc resistant member 30E. Can be suppressed. Therefore, while the arc discharge continues, the fibers of the constituent material of the arc resistant member 30E can be kept dense, the shunting of the arc current to the inner tube 21 can be suppressed, and damage such as opening of a hole in the inner tube 21 can be suppressed.

<Embodiment 5>
In the fifth embodiment, as shown in FIG. 6, a superconducting cable 1 </ b> F that is a single-core cable including one cable core 10 will be described. The superconducting cable 1F is different from the superconducting cable 1A of the first embodiment in that the number of the cable core 10 is one and no interposition member is required. In the case of a single-core cable, since there is a possibility of contacting the inner tube 21 over the entire circumference of the cable core 10, the arc-resistant member is configured by a cylindrical member that surrounds the entire circumference and the entire length of the cable core 10. It is necessary to Therefore, in the case of a single-core cable, the arc-resistant member 30F is normally arranged in a slack state (upper view in FIG. 6) or in an overlapping state, like the arc-resistant member described in the first or second embodiment. In the case of a ground fault of the cable core 10, a form that spreads outward and is in close contact with the inner surface of the inner tube 21 (the lower diagram in FIG. 6) can be suitably used.

  The present invention is not limited to these exemplifications, but is defined by the scope of the claims, and is intended to include all modifications within the scope and meaning equivalent to the scope of the claims. For example, the number of cable cores housed in the heat insulating pipe in the first to fourth embodiments can be two or four or more.

1A, 1B, 1C, 1D, 1E, 1F Superconducting cable 10, 10a, 10b, 10c Cable core 11 Former 12 Superconducting conductor layer 13 Electrical insulating layer 14 Ground layer 15 Protective layer 20 Heat insulating tube 21 Inner tube 22 Outer tube 24 Anticorrosion layer L Liquid refrigerant 30A, 30B, 30D, 30E, 30F Arc resistant member 40 Opening suppression structure 42A, 42B Extra length portion 440 Overlap portion 44, 44a, 44b, 44c Opening portion 46 Spacer 460 Space 50, 50a, 50b, 50c Intervening arc resistant member

Claims (9)

A cable core having a superconducting conductor layer and a ground layer provided on the outer periphery of the superconducting conductor layer via an electric insulating layer;
A heat insulating tube having an inner tube that houses the cable core and is filled with a liquid refrigerant, and an outer tube that forms a heat insulating layer outside the inner tube;
It is composed of a fiber material in which a plurality of fibers are densely arranged, and is interposed between the cable core and the inner tube, and a current accompanying an arc discharge caused by a ground fault generated in the cable core is shunted to the inner tube. An arc-resistant member that suppresses this,
Fibers of the fiber material by volume expansion when the arc-proof member and a component member provided near at least one of the arc-proof member and the cable core and positioned near the ground fault point of the cable core are vaporized. A superconducting cable comprising an opening suppression structure that suppresses the formation of a gap therebetween.   The said opening suppression structure is provided with the surplus length part which the arc-resistant member surrounds the outer periphery of the cable core, and spreads by volume expansion when the component member is vaporized, and is in close contact with the inner surface of the inner tube. The superconducting cable according to 1.   The superconducting cable according to claim 1, wherein the opening suppression structure includes a spacer that forms a space between a surface of the cable core near a ground fault point and the arc-resistant member.   The said opening prevention structure is provided with the opening part which the said arc-resistant member flows into the said inner tube | pipe side when the said arcuate member vaporizes. Superconducting cable.   The superconducting cable according to any one of claims 1 to 3, wherein the superconducting cable is a single-core cable having one cable core.   The superconducting cable according to any one of claims 1 to 4, wherein the superconducting cable is a multi-core cable having a plurality of the cable cores.   7. An intervening arc-resistant member interposed between the cable cores facing each other and suppressing an electric current accompanying an arc discharge caused by a ground fault generated in one of the cable cores from being shunted to the other cable core. The superconducting cable described.   The superconducting cable according to any one of claims 1 to 7, wherein the arc-resistant member is made of a fiber material containing at least one of aramid and silica.   The superconducting cable according to any one of claims 1 to 8, which is applied to a resistance grounding system.

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