JP6823941B2 - Cable branch structure and coating treatment tool - Google Patents

Description

The present invention relates to a cable branch structure and a coating treatment tool.

Conventionally, as a branch structure of a cable in which a plurality of branch cables are connected to a trunk cable, an electric field relaxation member is attached to a decoating portion of the branch cable (see, for example, Patent Document 1). In the branch structure of this cable, a plug-in type stress cone is inserted into the decoating portion of the branch cable as an electric field relaxation member.

Japanese Unexamined Patent Publication No. 2005-354843

Here, for example, in the above-mentioned cable branching structure, since a plug-in type stress cone is used, there is a problem that the covering work is troublesome and the construction time is long. Further, in the branch structure of the cable, it has been required to reduce the variation in the electric field relaxation performance for each product. Therefore, it has been required to easily cover the cable with the electric field relaxation member in a short time and to reduce the variation in the electric field relaxation performance.

The cable branching structure according to one embodiment of the present invention is a cable in which a first cable and a second cable are connected in a predetermined direction of a branch portion, and at least a third cable is connected in a direction opposite to the predetermined direction. It has a branched structure and includes an electric field relaxation member that covers the decoating portion of the first cable and the second cable, and the electric field relaxation member is a semi-conductive layer and an insulating layer of the first cable and the second cable, respectively. The stress cone is provided with a stress cone that covers the boundary portion between the cable and the stress cone, and an insulating member that covers the first cable and the second cable so as to be adjacent to the position on the branch side in the axial direction. , The insulating member is composed of a room temperature shrinkable insulating material.

According to such a form, the electric field relaxation member for relaxing the electric field is a stress cone covering the boundary between the semi-conductive layer and the insulating layer of each of the first cable and the second cable, and a stress cone. On the other hand, an insulating member for covering the first cable and the second cable is provided so as to be adjacent to the position on the branch portion side in the axial direction. Further, the stress cone is composed of a conductive material that is shrinkable at room temperature, and the insulating member is made of an insulating material that is shrinkable at room temperature. In this way, by using a member provided with a stress cone that shrinks at room temperature and an insulating member as the electric field relaxation member, when covering the coating stripping portion of the cable, the electric field relaxation member is aligned with the target position and the electric field is applied. By shrinking the relaxation member, it becomes possible to cover the coating removal portion. As a result, the coating with the electric field relaxation member can be performed easily and in a short time as compared with the case of using, for example, a plug-in type stress cone. Further, by using the stress cone of the conductive material as the electric field relaxation member, it is possible to reduce the variation in the electric field relaxation performance for each product as compared with the electric field relaxation by the high dielectric constant method, for example. From the above, the cable can be easily and quickly covered with the electric field relaxation member, and the variation in the electric field relaxation performance can be reduced.

In the branching structure of the cable according to another form, the insulating member may cover the outer peripheral surface of the stress cone in a part in the axial direction.

In the branch structure of the cable according to another embodiment, an insulating cylinder that covers the decoating portion of the first cable, the second cable, and the third cable and has a stress cone for the insulating cylinder is further provided, and the outer circumference of the stress cone is provided. The surface is exposed from the insulating member and may be in contact with the stress cone for the insulating tube.

The cable branching structure according to another embodiment further comprises a connecting fitting for connecting the first cable, the second cable, and the third cable to each other, and the connecting fitting is a first cable holding the first cable. A holding portion, a second holding portion that holds the second cable, a third holding portion that holds the third cable, and a first holding portion that is superposed on each other in a direction orthogonal to the axial direction. The head of the bolt inserted into the second holding portion and the third holding portion and the bolt inserted into the first holding portion, the second holding portion, and the third holding portion while inserting the bolt. A housing member for housing the unit may be provided.

The covering treatment tool according to one embodiment of the present invention covers a cable in which a first cable and a second cable are connected in a predetermined direction of a branch portion, and at least a third cable is connected in a direction opposite to the predetermined direction. A coating treatment tool for processing, which is a pullable tubular hollow first core member, a pullable tubular hollow second core member, and an outer peripheral side of the first core member and the second core member. The electric field relaxation member is provided with an electric field relaxation member that is held in a state of being expanded in diameter, and the electric field relaxation member is held in a state of being expanded in diameter on the outer peripheral side of the first core member and the second core member, and is shrinkable at room temperature. The stress cone composed of the above conductive material and the stress cone are held in a state of being expanded in diameter on the outer peripheral side of the first core member and the second core member so as to be adjacent to each other in the axial direction. , An insulating member made of a room temperature shrinkable insulating material.

According to the present invention, the cable can be easily and quickly covered with the electric field relaxation member, and the variation in the electric field relaxation performance can be reduced.

FIG. 1 is a cross-sectional view showing a branch structure of a cable coated by using the coating treatment tool according to the embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view showing a structure in the vicinity of the electric field relaxation member for the first branch cable and the second branch cable among the branch structures of the cables shown in FIG. FIG. 3 is a diagram showing an example of the structure of the electric field relaxation member. FIG. 4 is a diagram showing a coating treatment tool according to an embodiment of the present invention. FIG. 5 is a perspective view showing the connection fitting shown in FIG. FIG. 6 is a top view of the connection fitting shown in FIG. FIG. 7 is a front view of the connection fitting shown in FIG. FIG. 8 is a bottom view of the connection fitting shown in FIG. FIG. 9 is a left side view of the connection fitting shown in FIG. FIG. 10 is a right side view of the connection fitting shown in FIG. FIG. 11 is a rear view of the connection fitting shown in FIG. FIG. 12 is a cross-sectional view of the connection fitting shown in FIG. FIG. 13 is a perspective view of the accommodating member of the connection fitting shown in FIG. FIG. 14 is a cross-sectional view of the accommodating member shown in FIG. FIG. 15 is a diagram showing the relationship between the penetrating portion of the accommodating member and the head of the bolt. FIG. 16 is a diagram for explaining an assembly procedure of a branch structure of a cable according to an embodiment of the present invention. FIG. 17 is a diagram for explaining an assembly procedure of a cable branch structure according to an embodiment of the present invention. FIG. 18 is a diagram for explaining an assembly procedure of a branch structure of a cable according to an embodiment of the present invention. FIG. 19 is a diagram for explaining a procedure for assembling a branch structure of a cable according to an embodiment of the present invention. FIG. 20 is a diagram for explaining an assembly procedure of a branch structure of a cable according to an embodiment of the present invention. FIG. 21 is a diagram for explaining an assembly procedure of a branch structure of a cable according to an embodiment of the present invention. FIG. 22 is an enlarged cross-sectional view showing a branch structure of the cable according to the modified example. FIG. 23 is a diagram showing a structure of an electric field relaxation member having a branch structure of the cable shown in FIG. 22. FIG. 24 is a diagram showing the results of comparing Comparative Examples and Examples.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, the same or equivalent elements are designated by the same reference numerals, and duplicate description will be omitted.

FIG. 1 is a cross-sectional view showing a branch structure of a cable coated by using the coating treatment tool according to the present embodiment. FIG. 2 is an enlarged cross-sectional view showing a structure in the vicinity of the electric field relaxation member for the first branch cable and the second branch cable among the branch structures of the cables shown in FIG. In the branch structure 1 according to the present embodiment, the first branch cable (first cable) 2B and the second branch group (second cable) are connected in a predetermined direction of the branch portion, and the direction is opposite to the predetermined direction. The trunk cable (third cable) is connected. In the present embodiment, the branch structure 1 is a branch structure of a cable 2 in which a plurality of branch cables are connected to the trunk cable 2A. Of the plurality of branch cables, the first branch cable 2B and the second branch cable 2C extend in the direction opposite to the extending direction of the trunk cable 2A (left side of the paper in FIG. 1). The cables 2A, 2B and 2C are power cables. In this embodiment, the number of branch cables is two, but may be three. That is, the third branch cable may be branched from the trunk cable 2A. In this case, the third branch cable may extend in the extending direction of the trunk cable 2A. Further, the trunk cable may extend in the predetermined direction and the opposite side of the predetermined direction, and the branch cable may extend in the predetermined direction. In the following description, the direction in which the cable 2 extends is referred to as "axial direction". Of these, the extending direction of the trunk cable 2A (direction opposite to the predetermined direction) is referred to as "first direction D1", and the direction opposite to the extending direction of the trunk cable 2A (predetermined direction) is referred to as "second direction D1". It is referred to as "direction D2".

The cables 2A, 2B, and 2C include a conductor portion 2a, an insulating layer 2b, a semiconducting layer 2c, a cable shielding layer 2d, and a cable sheath 2e. The conductor portion 2a, the insulating layer 2b, the semi-conductive layer 2c, the cable shielding layer 2d, and the cable sheath 2e are arranged in this order from the inner circumference to the outer circumference. Further, the conductor portion 2a, the insulating layer 2b, the semi-conductive layer 2c, the cable shielding layer 2d, and the cable sheath 2e are exposed in this order from the tip side. The insulating layer 2b is a portion made of an insulating resin or the like, and covers the outer peripheral surface of the conductor portion 2a. Of the cables 2A, 2B, and 2C, the portion exposed from the cable sheath 2e, that is, the portion of the conductor portion 2a, the insulating layer 2b, the semiconductive layer 2c, and the cable shielding layer 2d is referred to as the coating removing portion 2f. There is. The trunk cable 2A is arranged so that the tip of the coating removing portion 2f, that is, the exposed conductor portion 2a is located on the side in the second direction D2. The branch cables 2B and 2C are arranged so that the tip of the coating removing portion 2f, that is, the exposed conductor portion 2a is located on the first direction D1 side. Then, the exposed conductor portion 2a of the trunk cable 2A and the exposed conductor portion 2a of the branch cables 2B and 2C are arranged so as to face each other, and are connected by a connection fitting 8 described later. In the present embodiment, the portion where the conductor portions 2a are connected to each other, that is, the portion of the connection fitting 8, corresponds to the branch portion.

The conductor portion 2a is formed by bundling a plurality of conductive wire rods. The insulating layer 2b is a tubular member made of an insulating material provided so as to cover the conductor portion 2a. The insulating layer 2b has a function of ensuring insulation on the outer periphery of the conductor portion 2a.

The semi-conductive layer 2c is a layer having semi-conductive property, and is composed of, for example, a cloth or paper impregnated with a conductive substance such as carbon. The semi-conductive layer 2c is arranged on the inner peripheral side of the cable shielding layer 2d to make the local high electric field portion generated by the overlap between the cable shielding layers 2d uniform and enhance the insulation of the cables 2A, 2B, and 2C. Has an effect.

The cable shielding layer 2d is a conductive layer provided to prevent electric shock and to allow leakage current of cables 2A, 2B, and 2C to flow. The material of the cable shielding layer 2d is, for example, copper tape, and in this case, the cable shielding layer 2d is also referred to as a shielding copper tape. The cable shielding layer 2d covers the outer periphery of the semiconductive layer 2c. The cable sheath 2e is made of, for example, vinyl chloride or polyethylene. The cable sheath 2e covers the outer periphery of the cable shielding layer 2d.

A grounding spring 5A is provided on the cable shielding layer 2d of the trunk cable 2A. A grounding spring 5B is provided on the cable shielding layer 2d of the branch cables 2B and 2C. The grounding spring 5B connects the cable shielding layer 2d of the first branch cable 2B and the cable shielding layer 2d of the second branch cable 2C in a state of being arranged in parallel with each other. Further, the waterproof tape 10 is wound around the cable sheath 2e of the first branch cable 2B and the cable sheath 2e of the second branch cable 2C in a state of being arranged in parallel with each other. A branching spacer (not shown) is provided between the cable sheath 2e of the first branch cable 2B and the cable sheath 2e of the second branch cable 2C.

Next, the branch structure 1 will be described with reference to FIGS. 1 and 2. The branch structure 1 includes electric field relaxation members 3A and 3B, an insulating cylinder 4, a shielding mesh 6, waterproof tubes 7A and 7B, and a connecting metal fitting 8.

The electric field relaxation member 3B is a member that covers a part of the insulating layer 2b and the semi-conductive layer 2c of the coating removing portion 2f of the branch cables 2B and 2C. The electric field relaxation member 3B includes a stress cone 21 and an insulating member 22. The stress cone 21 is a tubular member that covers the boundary between the semi-conductive layer 2c and the insulating layer 2b of the branch cables 2B and 2C, respectively. The stress cone 21 includes a tubular first stress cone 21A that covers a part of the insulating layer 2b and the semi-conductive layer 2c of the coating removing portion 2f of the first branch cable 2B, and a coating removing portion of the second branch cable 2C. A tubular second stress cone 21B that covers a part of the insulating layer 2b of 2f and the semiconductive layer 2c is provided. In the present embodiment, the end portion of the stress cone 21 on the second direction D2 side is arranged at an intermediate position in the axial direction of the semiconductive layer 2c. The end portion of the stress cone 21 on the first direction D1 side is arranged at an intermediate position (near the end portion on the second direction D2 side) of the insulating layer 2b in the axial direction. However, the axial length of the stress cone 21 is not limited, and it is sufficient that at least the boundary portion between the semiconductive layer 2c and the insulating layer 2b can be covered and the electric field can be sufficiently relaxed. The ends of the stress cones 21A and 21B on the first direction D1 side have a curved shape so that the inner diameter expands toward the outer peripheral side. As a result, the electric field spreads toward the outer periphery along the curved ends of the stress cones 21A and 21B. The stress cone 21 is composed of a conductive material that shrinks at room temperature. Specifically, as the conductive material that shrinks at room temperature, a conductive silicone rubber, a conductive EPDM rubber, or the like, or an insulating silicone rubber or an insulating EPDM rubber coated with a conductive coating is adopted. In FIGS. 1 to 3, the stress cones 21A and 21B are separated from each other, and the insulating member 22 is interposed in the gap. However, the stress cones 21A and 21B may be in contact with each other.

The insulating member 22 covers the outer peripheral surface of the stress cone 21 with respect to the stress cone 21, that is, the first insulating member 22 covers the outer peripheral surface of the stress cone 21 in a part in the axial direction. In the present embodiment, the insulating member 22 is adjacent to the stress cone 21 on the first direction D1 side, and the outer peripheral portion 23, which is a part extending toward the second direction D2 side, covers the stress cone 21 from the outer peripheral side. There is. In particular, as shown in FIG. 3B, the insulating member 22 is integrally formed so as to collectively cover the stress cones 21A and 21B, which are independent of each other as one tubular member. When viewed from the axial direction, the insulating member 22 is formed in a substantially circular or elliptical shape so as to include stress cones 21A and 21B arranged in parallel with each other. Therefore, the insulating member 22 has two through holes 22a and 22b that communicate with the through holes 21a of the first stress cone 21A and the through holes 21a of the second stress cone 21B, respectively. In the present embodiment, the end portion of the outer peripheral portion 23 of the insulating member 22 on the second direction D2 side is arranged at the same position as the end portion of the stress cones 21A and 21B on the second direction D2 side. The end portion of the insulating member 22 on the first direction D1 side is arranged at an intermediate position (near the end portion on the first direction D1 side) of the insulating layer 2b in the axial direction. However, the axial length of the insulating member 22 is not limited, and it is sufficient that the insulating performance can be sufficiently ensured. The insulating member 22 is made of a room temperature shrinkable insulating material. Specifically, insulating silicone rubber, insulating EPDM rubber, and the like are used as room temperature shrinkable insulating materials.

In the electric field relaxation member 3B, as shown in FIGS. 3A and 3B, the first stress cone 21A and the second stress cone 21B may have the same diameter. Such an electric field relaxation member 3B can be applied when the diameters of the branch cables 2B and 2C are substantially the same. Alternatively, as shown in FIGS. 3C and 3D, the first stress cone 21A and the second stress cone 21B may have different diameters. Here, the diameter of the second stress cone 21B is smaller than that of the first stress cone 21A. Such an electric field relaxation member 3B can be applied when the diameters of the branch cables 2B and 2C are different. In the examples shown in FIGS. 1 and 2, the electric field relaxation members 3B having different diameters of the stress cones 21A and 21B are used.

Here, the electric field relaxation member 3B is configured as a coating treatment tool 100 as shown in FIG. 4 before coating. As shown in FIGS. 4A and 4B, the covering treatment tool 100 includes a pullable tubular hollow first core member 101A, a pullable tubular hollow second core member 101B, and a first pullable tubular hollow core member 101B. The electric field relaxation member 3B is provided on the outer peripheral side of the core member 101A and the second core member 101B, which are held in an expanded state. The stress cone 21 is held in a state of being enlarged on the outer peripheral side of the first core member 101A and the second core member 101B. That is, the first stress cone 21A is held in a state of being expanded in diameter by the first core member 101A. The second stress cone 21B is held in a state of being expanded in diameter by the second core member 101B. The insulating member 22 is held in a state of being expanded to the outer peripheral side of the first core member 101A and the second core member 101B so as to be adjacent to the stress cone 21 in the axial direction.

The first core member 101A is a cylindrical tubular hollow member having a dismantling line formed on the wall surface over the entire length. The dismantling line is provided so as to orbit around the axis of the first core member 101A, or to gradually advance in the axial direction while orbiting and reversing. In the present embodiment, as a disassembly line, a continuous spiral groove 101a provided so as to gradually advance in the axial direction (axial direction of the diameter-expanding holding member) while rotating around the axis of the first core member 101A is provided. It is provided. Hereinafter, the “disassembly line” will be described as being a continuous spiral groove 101a. As the material of the first core member 101A, for example, a resin such as polyethylene, polypropylene, or ABS is used. Further, if necessary, these resins can be used to form a multilayer structure. The first core member 101A can be pulled out as a core ribbon 101b which is a string-like body along the continuous spiral groove 101a. The portion where the continuous spiral groove 101a is formed has a smaller thickness than the periphery of the continuous spiral groove 101a and is easily broken. Further, the dismantling line is not limited to the form formed in a spiral shape such as the continuous spiral groove 101a, and may be formed in an SZ shape, for example, and may have any shape as long as it can be pulled out.

Therefore, when the core ribbon 101b is pulled, the first core member 101 is sequentially broken at the portion of the continuous spiral groove 101a and is continuously pulled out as a new core ribbon 101b. Since the continuous spiral grooves 101a are formed at a constant pitch, the width of the core ribbon 101b to be pulled out is also constant. However, it does not have to be constant. The continuous spiral groove 101a may be formed only on the inner peripheral surface of the first core member 101, may be formed only on the outer peripheral surface, or may be formed on both the inner peripheral surface and the outer peripheral surface. Good. Further, in the production of the first core member 101 having the continuous spiral groove 101a, for example, the core ribbon 101b is spirally swirled and the adjacent core ribbons 101b are fixed by adhesion, welding, engagement, or a combination thereof. It may be performed by directly forming the continuous spiral groove 101a in the cylindrical member. Further, as a tubular hollow diameter-expanding holding member that can be pulled out, the diameter-expanding holding member has a ribbon shape as described above, and the diameter of the first stress cone 21A and the insulating member 22 are sequentially reduced by unraveling the ribbon. In some embodiments, the diameter-expanding holding member slides with respect to the electric field relaxation member 3B and is pulled out from the electric field relaxation member 3B to be detached.

The first core member 101A has a first end portion 101c that is a start end side that is pulled out as a core ribbon 101b, and a second end portion 101d that is a end end side that is pulled out as a core ribbon 101b. An exposed portion is formed in the vicinity of the first end portion 101c where the electric field relaxation member 3B is not wound and the outer peripheral surface of the first core member 101A is exposed, and the electric field relaxation member 3B is also formed in the vicinity of the second end portion 101d. Is not wound, and an exposed portion is formed in which the outer peripheral surface of the first core member 101A is exposed.

The core ribbon 101b disassembled from the first end 101c is passed through the inside of the first core member 101A and pulled out from the second end 101d side. By pulling out the core ribbon 101b on the side of the second end 101d, the first core member 101 is sequentially disassembled from the first end 101c toward the second end 101d. In the present embodiment, since the continuous spiral groove 101a is formed over the entire length of the first core member 101, the first end 101c to the second end 101d are completely the first. It is possible to disassemble the core member 101. However, it suffices if a continuous spiral groove is formed at least in the portion of the first core member 101A that expands and holds the electric field relaxation member 3B. For example, a predetermined position on the second end 101d side is formed. There may be a portion in the range where the continuous spiral groove is not formed. Since the second core member 101B has the same configuration as the first core member 101A, the description thereof will be omitted.

Returning to FIG. 1, the electric field relaxation member 3A is a member that covers a part of the insulating layer 2b and the semi-conductive layer 2c of the coating removal portion 2f of the trunk cable 2A. The electric field relaxation member 3A includes a stress cone 11 and an insulating member 12. The stress cone 11 is a tubular member that covers the boundary between the semi-conductive layer 2c and the insulating layer 2b of the trunk cable 2A. In the present embodiment, the end portion of the stress cone 11 on the first direction D1 side is arranged at an intermediate position in the axial direction of the semiconductive layer 2c. The end portion of the stress cone 11 on the second direction D2 side is arranged at an intermediate position in the axial direction of the insulating layer 2b (near the end portion on the first direction D1 side). The end portion of the stress cone 11 on the second direction D2 side has a curved shape so that the inner diameter expands toward the outer peripheral side, and has the same function as the stress cone 21. However, the axial length of the stress cone 11 is not limited, and it is sufficient that at least the boundary portion between the semiconductive layer 2c and the insulating layer 2b can be covered and the electric field can be sufficiently relaxed. The stress cone 11 is configured to contain a room temperature shrinkable conductive material similar to the stress cone 21.

The insulating member 12 is a tubular member that covers the trunk cable 2A so as to be adjacent to the position of the branch portion side in the axial direction, that is, the position on the second direction D2 side with respect to the stress cone 11. The insulating member 12 is a member for preventing the electric field spreading along the stress cone 11 from going in the axial direction. The insulating member 12 covers the outer peripheral surface of the stress cone 11 in a part in the axial direction. In the present embodiment, the insulating member 12 is adjacent to the stress cone 11 on the second direction D2 side, and the outer peripheral portion 13 which is a part extending toward the first direction D1 side covers the stress cone 11 from the outer peripheral side. There is. The insulating member 12 has a through hole that communicates with the through hole of the stress cone 11. In the present embodiment, the end portion of the outer peripheral portion 13 of the insulating member 12 on the first direction D1 side is arranged at the same position as the end portion of the stress cone 11 on the first direction D1 side. The end portion of the insulating member 12 on the second direction D2 side is arranged at an intermediate position (near the end portion on the second direction D2 side) of the insulating layer 2b in the axial direction. However, the axial length of the insulating member 12 is not limited, and it is sufficient that the insulating performance can be sufficiently ensured. The insulating member 12 is made of a room temperature shrinkable insulating material similar to the insulating member 22.

The electric field relaxation member 3A is configured as a coating treatment tool 110 as shown in FIG. 17 before coating. The covering treatment tool 110 includes a core member having the same meaning as the above-mentioned covering treatment tool 100, and an electric field relaxation member 3A held in a state of being expanded on the outer peripheral side of the core member.

Returning to FIG. 1, the insulating cylinder 4 is a member that covers the entire coating removing portion 2f of the trunk cable 2A and the coating removing portion 2f of the branch cables 2B and 2C. In the present embodiment, the insulating cylinder 4 includes an internal conductive layer 4A, a reinforcing insulator 4B, and an external conductive layer 4C. Ethylene propylene rubber, silicone rubber, or the like having high insulating properties and excellent molding processability is used as the base rubber for the insulating cylinder 4, and the internal conductive layer 4A, the reinforcing insulator 4B, and the external conductive layer 4C are used, for example. , A component integrally molded so as to have a spindle shape, or a component integrally molded with an internal conductive layer 4A and a reinforcing insulator 4B and subjected to conductive coating as an external conductive layer 4C. .. However, depending on the voltage, the insulating cylinder 4 may have a simple cylindrical shape instead of a spindle shape. The internal conductive layer 4A is provided so as to cover the vicinity of the tips of the connection fitting 8 and the electric field relaxation members 3A and 3B in the coated state. The reinforcing insulator 4B is arranged on the outer peripheral side of the internal conductive layer 4A, and is provided in a wider range in the axial direction than the internal conductive layer 4A. The external conductive layer 4C is arranged on the outer peripheral side of the reinforcing insulator 4B. In the present embodiment, the length of the external conductive layer 4C is set to be substantially the same as that of the reinforcing insulator 4B.

Before coating, the insulating cylinder 4 is configured as a coating treatment tool 120 as shown in FIG. The covering treatment tool 120 includes a core member having the same meaning as the above-mentioned covering treatment tool 100, and an insulating cylinder 4 held in a state of being expanded on the outer peripheral side of the core member.

Returning to FIG. 1, the shielding mesh 6 is a member that covers the outer periphery of the insulating cylinder 4. The shielding mesh 6 is a member for shielding electromagnetic waves from the coating removing portion 2f of the cables 2A, 2B, and 2C. The end of the shielding mesh 6 on the first direction D1 side is held by the grounding spring 5A, and the end of the shielding mesh 6 on the second direction D2 side is held by the grounding spring 5B. The shielding mesh 6 is made of, for example, a material such as copper or a copper wire whose surface is tin-plated.

The waterproof tube 7A is a member for ensuring the waterproofness of the branch structure 1 by covering the entire branch structure 1. The waterproof tube 7 covers the entire portion covered with the shielding mesh 6 and covers the vicinity of the end of the cable sheath 2e of the cables 2A, 2B, and 2C. The end of the waterproof tube 7 on the D1 side in the first direction covers the vicinity of the end of the cable sheath 2e of the trunk cable 2A. The end of the waterproof tube 7 on the D2 side in the second direction covers up to the position of the waterproof tape 10 provided near the end of the cable sheath 2e of the branch cables 2B and 2C. The waterproof tube 7B is a member that further covers the vicinity of the end portion of the waterproof tube 7A on the first direction D1 side. The waterproof tube 7B covers the vicinity of the end of the cable sheath 2e of the trunk cable 2A and the vicinity of the grounding spring 5A. The waterproof tubes 7A and 7B are made of materials such as insulating silicone rubber and insulating EPDM rubber.

Before coating, the waterproof tubes 7A and 7B are configured as coating treatment tools 130A and 130B as shown in FIG. The coating treatment tools 130A and 130B include a core member having the same purpose as the above-mentioned coating treatment tool 100, and waterproof tubes 7A and 7B held in a state of being expanded on the outer peripheral side of the core member.

Returning to FIG. 1, the connection fitting 8 is a fitting for connecting the trunk cable 2A, the first branch cable 2B, and the second branch cable 2C to each other. The connection fitting 8 includes a first holding portion 31 for holding the first branch cable 2B, a second holding portion 32 for holding the second branch cable 2C, and a third holding portion for holding the trunk cable 2A. A 33, a bolt 34 (see FIG. 12), and a housing member 36 for accommodating the head 34a of the bolt 34 are provided.

The configuration of the connection fitting 8 will be described in detail with reference to FIGS. 5 to 14. In the present embodiment, the conductor portion 2a of the trunk cable 2A is sandwiched between the conductor portion 2a of the first branch cable 2B and the semiconducting layer 2c of the second branch cable 2C. It is connected to 2B and 2C. Therefore, the third holding portion 33 is overlapped so as to be sandwiched between the first holding portion 31 and the second holding portion 32. The holding portions 33 are superposed on each other in a direction orthogonal to the axial direction. In the following description, the direction will be referred to as a "superimposition direction". The stacking order of the cables 2A, 2B, and 2C, that is, the stacking order of the holding portions 31, 32, and 33 is not particularly limited and may be changed as appropriate. The bolts 34 are inserted into the holding portions 31, 32, 33 that are overlapped with each other in the overlapping direction. The bolt 34 is inserted from the direction in which the head 34a is arranged on the side of the second holding portion 32. Therefore, in the present embodiment, the accommodating member 36 is arranged outside the second holding portion 32. However, the insertion direction of the bolt 34 is not particularly limited. That is, the accommodating member 36 may be arranged outside the first holding portion 31. In order to prevent the cables 2A, 2B, and 2C from rotating with each other, the bolts 34 are inserted into the holding portions so that a plurality of bolts 34 are arranged in the axial direction. In this embodiment, two bolts 34 are inserted, but one or three or more bolts 34 may be inserted.

The first holding portion 31 includes a connecting portion 41 connected to the conductor portion 2a of the first branch cable 2B, and an insertion portion 42 through which the bolt 34 is inserted. The connecting portion 41 is arranged in the second direction D2, and the insertion portion 42 is arranged in the first direction D1. The connecting portion 41 has a cylindrical shape extending in the axial direction so as to have an internal space 41a for receiving the conductor portion 2a of the first branch cable 2B. The internal space 41a of the connecting portion 41 is opened at the end on the second direction D2 side in order to receive the conductor portion 2a, and is sealed at the end on the first direction D1 side. The insertion portion 42 is formed so as to extend from the end portion of the connecting portion 41 in the first direction D1 toward the first direction D1. The insertion portion 42 is formed with a through hole 42a penetrating in the overlapping direction in order to insert the bolt 34 (particularly see FIG. 12). Two through holes 42a are formed so as to be arranged in the axial direction. Further, in the insertion portion 42, a seat surface 42b for surface contact with the third holding portion 33 is formed inside in the overlapping direction. The seat surface 42b is a plane extending in a direction orthogonal to the superposition direction. Of the insertion portions 42, the outer outer peripheral surface 42c in the overlapping direction is an arcuate curved surface that is continuous with the outer peripheral surface of the connecting portion 41. The through hole 42a has a large diameter portion 42d whose inner diameter is enlarged by counterbore processing or the like on the outer peripheral surface 42c side. A nut 35 connected to the bolt 34 can be accommodated in the large diameter portion 42d.

The second holding portion 32 includes a connecting portion 43 connected to the conductor portion 2a of the second branch cable 2C, and an insertion portion 44 through which the bolt 34 is inserted. The connecting portion 43 is arranged in the second direction D2, and the insertion portion 44 is arranged in the first direction D1. The connecting portion 43 has a cylindrical shape extending in the axial direction so as to have an internal space 43a for receiving the conductor portion 2a of the second branch cable 2C. The internal space 43a of the connecting portion 43 is opened at the end on the second direction D2 side in order to receive the conductor portion 2a, and is sealed at the end on the first direction D1 side. The insertion portion 44 is formed so as to extend from the end portion of the connecting portion 43 in the first direction D1 toward the first direction D1. The insertion portion 44 is formed with a through hole 44a penetrating in the stacking direction in order to insert the bolt 34 (particularly see FIG. 12). Two through holes 44a are formed so as to be arranged in the axial direction. Further, a seat surface 44b for surface contact with the third holding portion 33 is formed inside the insertion portion 44 in the overlapping direction. Further, a seat surface 44c for surface contact with the accommodating member 36 is formed on the outer side of the insertion portion 44 in the overlapping direction. The seat surfaces 44b and 44c are planes extending in a direction orthogonal to the superposition direction.

The third holding portion 33 includes a connecting portion 45 connected to the conductor portion 2a of the trunk cable 2A, and an insertion portion 46 through which the bolt 34 is inserted. The connecting portion 45 is arranged in the first direction D1, and the insertion portion 46 is arranged in the second direction D2. The connecting portion 45 has a cylindrical shape extending in the axial direction so as to have an internal space 45a for receiving the conductor portion 2a of the trunk cable 2A. The internal space 45a of the connecting portion 45 is opened at the end on the first direction D1 side in order to receive the conductor portion 2a, and is sealed at the end on the second direction D2 side. The insertion portion 46 is formed so as to extend from the end portion of the connecting portion 45 in the second direction D2 toward the second direction D2. The insertion portion 46 is formed with a through hole 46a penetrating in the stacking direction in order to insert the bolt 34 (particularly see FIG. 12). Two through holes 46a are formed so as to be arranged in the axial direction. Further, on one side of the insertion portion 46 in the overlapping direction, a seat surface 46b for surface contact with the first holding portion 31 is formed. Further, on the other side of the insertion portion 46 in the overlapping direction, a seat surface 46c for surface contact with the second holding portion 32 is formed. The seat surfaces 46b and 46c are planes extending in a direction orthogonal to the superposition direction.

The accommodating member 36 is a member through which the bolt 34 is inserted and accommodates the head 34a of the bolt 34 inserted into the first holding portion 31, the second holding portion 32, and the third holding portion 33. The accommodating member 36 is a semi-cylindrical member extending in the axial direction. As shown in FIGS. 12 to 14, the accommodating member 36 is formed with a penetrating portion 47 penetrating in the overlapping direction in order to insert the bolt 34. Two penetrating portions 47 are formed so as to be lined up in the axial direction. Further, a seat surface 36a for surface contact with the second holding portion 32 is formed inside the accommodating member 36 in the overlapping direction. The seat surface 36a is a plane extending in a direction orthogonal to the superposition direction. Of the accommodating members 36, the outer outer peripheral surface 36b in the overlapping direction is an arcuate curved surface.

Next, the penetrating portion 47 of the accommodating member 36 will be described with reference to FIGS. 13 to 15. The penetrating portion 47 has an accommodating portion 48 for accommodating the head portion 34a of the bolt 34 and a through hole 49 for inserting the shaft portion 34b of the bolt 34 in this order from the outer peripheral surface 36b side to the seat surface 36a side. ing. The through hole 49 has a circular shape when viewed from the through direction. The diameter of the through hole 49 is smaller than the first dimension W1 (see FIG. 15) of the head 34a and larger than the diameter of the shaft portion 34b. For the sake of explanation, as shown in FIG. 15A, among the hexagonal shapes of the head 34a of the bolt 34, the dimension between the pair of sides facing each other is referred to as "first dimension W1", and each other is referred to as "first dimension W1". The dimension between the pair of opposing vertices is referred to as "second dimension W2".

The accommodating portion 48 has a substantially rectangular shape when viewed from the penetrating direction. The accommodating portion 48 has a pair of inner wall surfaces 48a and 48a facing each other in the axial direction (direction in which the accommodating member 36 extends) and a pair of inner wall surfaces 48b and 48b facing each other in the direction orthogonal to the axial direction. ing. Here, the accommodating portion 48 has a function of accommodating the head portion 34a of the bolt 34 and preventing contact with other members or the like. Further, the accommodating portion 48 allows accommodating the head 34a of the bolt 34, but has a function of preventing the accommodated head 34a from rotating, that is, restricting rotation. Specifically, as shown in FIG. 14, the depth dimension H2 of the accommodating portion 48 is larger than the height dimension H1 of the head 34a. The depth dimension H2 of the accommodating portion 48 includes a portion (here, the upper end of the inner wall surface 48b) arranged at the lowest position among the edges of the outer peripheral surface 36b of the opening of the accommodating portion 48 and the accommodating portion. It is a dimension between the bottom surface 48c of 48 and. The width dimension L1 between the inner wall surfaces 48b and 48b is larger than the first dimension W1 of the head 34a and smaller than the second dimension W2. Further, the width dimension L2 between the inner wall surfaces 48a and 48a is larger than the second dimension W2 of the head 34a. However, the width dimension L2 between the inner wall surfaces 48a and 48a is larger than the first dimension W1 of the head 34a and smaller than the second dimension W2, and the width dimension L1 between the inner wall surfaces 48b and 48b is the head. It may be larger than the second dimension W2 of 34a. Further, the shape and dimensional relationship of the accommodating portion 48 are not particularly limited as long as the head 34a of the bolt 34 can be accommodated and the accommodated head 34a can be prevented from rotating.

Next, a method of assembling the branch structure 1 of the cable 2 according to the present embodiment will be described with reference to FIGS. 16 to 21. As shown in FIG. 16A, the cable sheath 2e of each cable 2A, 2B, 2C is removed to expose the conductor portion 2a, the insulating layer 2b, the semiconductive layer 2c, and the cable shielding layer 2d, and cover the cables. The removal portion 2f is formed. Next, as shown in FIG. 16B, the conductor portions 2a of the cables 2B, 2C, and 2A are connected to the connecting portions 41, 43, 45 of the holding portions 31, 32, 33. The connection is made by compression. Further, a waterproof spacer is attached to the branch cables 2B and 2C, and the waterproof tape 10 is wrapped around the branch cables 2B and 2C.

Next, as shown in FIG. 17, necessary covering treatment tools 100, 110, 120, 130A, and 130B are attached to the cables 2A, 2B, and 2C in advance. Specifically, the covering treatment tool 110 of the electric field relaxation member 3A, the covering treatment tool 120 of the insulating cylinder 4, and the covering treatment tool 130B of the waterproof tube 7B are attached to the trunk cable 2A. Further, the coating treatment tool 100 of the electric field relaxation member 3B and the coating treatment tool 130A of the waterproof tube 7A are attached to the branch cables 2B and 2C. A folded shielding mesh 6 is attached to the branch cables 2B and 2C.

Next, as shown in FIG. 18A, the holding portions 31, 32, 33 and the accommodating member 36 are overlapped with each other, and the bolt 34 is inserted to fasten each member. As a result, the cables 2A, 2B, and 2C are connected by the connection fitting 8. Further, by aligning the covering treatment tool 100 and the branch cables 2B and 2C and disassembling the core member, the branch cables 2B and 2C are covered with the electric field relaxation member 3B as shown in FIG. 18B. .. Further, the trunk cable 2A is covered with the electric field relaxation member 3A. At this time, the core members are disassembled so that the electric field relaxation members 3A and 3B contract from the semiconductive layer 2c side.

Next, as shown in FIG. 19A, the branch portions of the cables 2A, 2B, 2C and the covering treatment tool 120 are aligned (both ends of the insulating cylinder 4 are the ends of the electric field relaxation members 3A, 3B). The branch portion is covered with the insulating cylinder 4 by disassembling the core member by performing (alignment so as to match with). Next, as shown in FIG. 19B, the insulating cylinder 4 is covered with the shielding mesh 6. At this time, both ends of the shielding mesh 6 are fixed by grounding springs 5A and 5B, respectively.

Next, as shown in FIGS. 20A and 20B, the covering treatment tool 130A is aligned with the shielding mesh 6 and the core member is disassembled to cover the portion with the waterproof tube 7A. At this time, the ends of the waterproof tube 7A on the branch cables 2B and 2C sides are aligned with the waterproof tape 10. Next, as shown in FIGS. 21 (a) and 21 (b), the covering treatment tool 130B is aligned with the end of the waterproof tube 7A on the trunk cable 2A side, the core member is disassembled, and the waterproof tube 7B is covered. .. As described above, the branch structure 1 of the cable 2 is completed.

Next, the operation / effect of the branch structure 1 of the cable 2 according to the present embodiment will be described.

According to the branch structure 1 of the cable 2 according to the present embodiment, the electric field relaxation member 3B for relaxing the electric field includes the semi-conductive layer 2c and the insulating layer of the first branch cable 2B and the second branch cable 2C, respectively. The stress cone 21 that covers the boundary portion with 2b, and the insulating member 22 that covers the first branch cable 2B and the second branch cable 2C so as to be adjacent to the position on the branch portion side in the axial direction with respect to the stress cone 21. And have. Further, the stress cone 21 is made of a room temperature shrinkable conductive material, and the insulating member 22 is made of a room temperature shrinkable insulating material. As described above, when the electric field relaxation member 3B is provided with the room temperature shrinkable stress cone 21 and the insulating member 22, the electric field is applied to the target position when the coating removing portion 2f of the branch cables 2B and 2C is covered. By aligning the relaxation member 3B and shrinking the electric field relaxation member 3B, it is possible to cover a part of the insulating layer 2b and the semi-conductive layer 2c of the coating removing portion 2f.

For example, when the branch cables 2B and 2C are covered with a plug-in type stress cone, the operator must apply force to insert the stress cone into the branch cables 2B and 2C, which requires labor and time. Was hanging. On the other hand, when the tightening force by the stress cone is loosened in consideration of ease of attachment, sufficient electric field relaxation property may not be ensured. On the other hand, by adopting the structure of the present embodiment, the coating with the electric field relaxation member 3B can be performed easily and in a short time as compared with the case of using the plug-in type stress cone. Further, the electric field relaxation member 3B is tightened to the branch cables 2B and 2C with a sufficient force, so that sufficient electric field relaxation property can be ensured. Further, by using the stress cone 21 made of a conductive material as the electric field relaxation member 3B, it is possible to reduce the variation in the electric field relaxation performance for each product as compared with the electric field relaxation by the high dielectric constant method, for example. For example, in the high dielectric constant method, the electric field relaxation performance of each product varies greatly due to variations in materials and molding. On the other hand, by using the stress cone 21 of the conductive material as the electric field relaxation member 3B, it is possible to reduce the variation in the electric field relaxation performance due to the variation in the material and molding as compared with the high dielectric constant method. Since the electric field relaxation performance of the stress cone depends on the shape of the conductive material, it is possible to reduce the variation in the electric field relaxation performance for each product by correctly designing the shape. From the above, according to the present embodiment, the branch cable can be easily and quickly covered with the electric field relaxation member 3B, and the variation in the electric field relaxation performance can be reduced. The coating treatment tool 100 also has the same action and effect.

In the branch structure 1 of the cable 2, the insulating member 22 covers the outer peripheral surface of the stress cone 21 in a part in the axial direction. In this case, since it is not necessary to provide a stress cone in the insulating cylinder, the number of parts can be reduced.

The branch structure 1 of the cable 2 further includes a connection fitting 8 for connecting the trunk cable 2A, the first branch cable 2B, and the second branch cable 2C to each other. The connection fitting 8 includes a first holding portion 31 for holding the first branch cable 2B, a second holding portion 32 for holding the second branch cable 2C, and a third holding portion for holding the trunk cable 2A. The bolt 34 inserted into the first holding portion 31, the second holding portion 32, and the third holding portion 33, which are overlapped with each other in the direction orthogonal to the axial direction, and the bolt 34 are inserted into the 33. , A first holding portion 31, a second holding portion 32, and a housing member 36 for accommodating the head 34a of the bolt 34 inserted into the third holding portion 33. In this case, the head 34a of the bolt 34, in which the holding portions are overlapped and fixed, is accommodated in the accommodating member 36. As a result, it is possible to prevent the head 34a of the bolt 34 from coming into contact with other members or the like. Further, by accommodating the head 34a in the accommodating member 36, the head 34a can be prevented from rotating, so that the burden of tightening the bolt 34 can be reduced.

The present invention is not limited to the above-described embodiment. For example, the modes shown in FIGS. 22 and 23 may be adopted. That is, the outer peripheral surface of the stress cone 21 is exposed from the insulating member 22, and may be in contact with the stress cone 4D for the insulating cylinder. The stress cone 4D for an insulating cylinder extends further toward the first direction D1 side than the end portion of the stress cone 21 on the first direction D1 side, and the end portion extends toward the outer peripheral side. When such a configuration is adopted, since the electric field relaxation is performed by including the stress cone 4D for the insulation cylinder on the insulation cylinder 4 side and the electric field relaxation member 3B, the thickness of the electric field relaxation member 3B itself can be reduced.

Further, the branch structure of the cable is not limited to the above-described embodiment, and the positional relationship of various members and the like may be appropriately changed. Further, the order of assembly is not particularly limited.

[Example]
Next, an example and a comparative example are compared with reference to FIG. 24. As an example, the trunk cable, the first branch cable, and the second branch cable each have a conductor cross-sectional area of 150 mm ^2, and the insulating material of the electric field relaxation member for the trunk cable and the electric field relaxation member for the branch cable is silicone rubber, which is conductive. A branch structure of a cable using silicone rubber as the sex material was prepared. As a comparative example, the trunk cable, the first branch cable, and the second branch cable each have a conductor cross-sectional area of 150 mm ^2, and the insulating material of the electric field relaxation member for the trunk cable and the electric field relaxation member for the branch cable is silicone rubber. A branch structure of a cable using silicone rubber as the dielectric material was prepared.

For examples and comparative examples, a lightning impulse withstand voltage test (JCAA A503) of "22kV / 33kV cross-linked polyethylene insulated power cable linear connection performance standard 33kV section (JCAA A503)" of "Japan Electric Power Cable Connection Technology Association" The test was conducted in accordance with 305 kV (negative electrode property), 3 times). When the test was cleared under the condition of −305kV, 3 times, the test voltage was boosted by -10kV until the connection of the branch structure or the terminal was broken, and the test was carried out. Tests were conducted on Examples and Comparative Examples relating to a plurality of molding lots. The results of this test are shown in FIG.

As shown in FIG. 24, in the examples, the same results were obtained regardless of the molding lot. On the other hand, in the comparative example, variations were confirmed in the results depending on the molding lot. From this, it is understood that in the examples, stable electric field relaxation performance can be obtained without depending on the variation of the molding lot.

1 ... Branch structure, 2 ... Cable, 2A ... Trunk cable, 2B, 2C ... Branch cable, 2f ... Coating removal part, 3B ... Electric field relaxation member, 4 ... Insulation cylinder, 4D ... Insulation cylinder melted stress cone, 8 ... Connection bracket , 21 ... stress cone, 22 ... insulating member, 31 ... first holding part, 32 ... second holding part, 33 ... third holding part, 34 ... bolt, 34a ... head, 36 ... accommodating member, 100 ... Coating treatment tool, 101 ... Core member.

Claims (6)

It is a branch structure of a cable in which a first cable and a second cable are connected in a predetermined direction of a branch portion, and at least a third cable is connected in a direction opposite to the predetermined direction.
An electric field relaxation member for covering the decoating portion of the first cable and the second cable is provided.
The electric field relaxation member is
A first stress cone and a second stress cone that cover the boundary between the semi-conductive layer and the insulating layer of the first cable and the second cable, respectively.
The first stress cone and the second stress cone are integrally formed so as to be adjacent to the position on the branch side in the axial direction, and cover the first cable and the second cable. With an insulating member,
The stress cone is composed of a conductive material that shrinks at room temperature.
The insulating member is a branch structure of a cable made of a room temperature shrinkable insulating material. The cable branching structure according to claim 1, wherein the insulating member covers the outer peripheral surface of the stress cone in a part in the axial direction. An insulating cylinder that covers the decoating portion of the first cable, the second cable, and the third cable and has a stress cone for an insulating cylinder is further provided.
The cable branching structure according to claim 1, wherein the outer peripheral surface of the stress cone is exposed from the insulating member and is in contact with the stress cone for the insulating cylinder. Further provided with connecting fittings for connecting the first cable, the second cable, and the third cable to each other.
The connection fitting
A first holding portion for holding the first cable and
A second holding portion for holding the second cable and
A third holding portion for holding the third cable and
A bolt inserted into the first holding portion, the second holding portion, and the third holding portion, which are superposed on each other in a direction orthogonal to the axial direction.
1. A claim 1 comprising inserting the bolt and accommodating the first holding portion, the second holding portion, and the head of the bolt inserted into the third holding portion. The branch structure of the cable according to any one of 3 to 3. A coating treatment tool that coats a cable in which a first cable and a second cable are connected in a predetermined direction of a branch portion and at least a third cable is connected in a direction opposite to the predetermined direction.
With a retractable tubular hollow first core member,
With a retractable tubular hollow second core member,
The first core member and the electric field relaxation member held on the outer peripheral side of the second core member in an expanded state are provided.
The electric field relaxation member is
A stress cone that is held on the outer peripheral side of the first core member and the second core member in an expanded state and is composed of a conductive material that shrinks at room temperature.
The stress cone is held in a state of being expanded in diameter on the outer peripheral side of the first core member and the second core member so as to be adjacent to each other in the axial direction, and is composed of a room temperature shrinkable insulating material. A coating treatment tool including an insulating member. It is a branch structure of a cable in which a first cable and a second cable are connected in a predetermined direction of a branch portion, and at least a third cable is connected in a direction opposite to the predetermined direction.
An electric field relaxation member for covering the decoating portion of the first cable and the second cable is provided.
The electric field relaxation member is
A stress cone that covers the boundary between the semi-conductive layer and the insulating layer of each of the first cable and the second cable,
The stress cone is provided with an insulating member that covers the first cable and the second cable so as to be adjacent to the position on the branch side in the axial direction.
The stress cone is composed of a conductive material that shrinks at room temperature.
The insulating member is made of a room temperature shrinkable insulating material.
An insulating cylinder that covers the decoating portion of the first cable, the second cable, and the third cable and has a stress cone for an insulating cylinder is further provided.
A cable branch structure in which the outer peripheral surface of the stress cone is exposed from the insulating member and is in contact with the stress cone for the insulating cylinder.

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