Intermediate connection unit for power cables and method for connecting power cables

Abstract

To provide an intermediate connection unit for a power cable which enables easy formation of a shielding layer in a short time by extracting a large-diameter holding material, and a method for connecting a power cable.SOLUTION: An intermediate connection unit for a power cable is for assembling a cable intermediate connection structure for connecting the end of a first power cable and the end of a second power cable, and includes a large-diameter holding material, a rubber unit to which the large-diameter holding material is inserted and that has a diameter enlarged by the large-diameter holding material, and a shielding layer which is provided on the outer periphery of the rubber unit and is composed of a plurality of shielding wire materials arranged so as to be separated from each other.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an intermediate connection unit for power cables and a method for connecting power cables. [Background technology]

[0002] BACKGROUND ART Cable mid-span joint structures that connect the ends of power cables together have been known.

[0003] For example, Patent Document 1 describes an insulating cylinder with a diameter-expanding support cylinder, in which a cold-shrinkable insulating cylinder is supported by a diameter-expanding support cylinder for expansion. In the insulating cylinder with a diameter-expanding support cylinder of Patent Document 1, the expanding support cylinder is formed by stacking multiple cylindrical cores in inner and outer layers, and at least the cylindrical core on the side that comes into contact with the insulating cylinder is formed by a spiral core formed by spirally winding a string-like body.

[0004] As in Patent Document 1, in assembling a conventional cable middle joint structure, first, before connecting the ends of power cables, a rubber unit and a protective tube whose diameter has been expanded by a diameter expansion retaining member are passed through the power cables and left waiting in a portion other than the ends of the power cables. After connecting the ends of the power cables, the rubber unit that has been waiting on the power cables in advance is moved to the connection portion, the diameter expansion retaining member is pulled out of the rubber unit, and the rubber unit is attached to the connection portion. Next, a shielding layer is tightly wound around the outer periphery of the rubber unit, and a protective layer is tightly wound around the outer periphery of the shielding layer. After that, the protective tube that has been waiting on the power cables in advance is moved to the position of the rubber unit. Next, a liquid compound is injected through an injection hole provided in the protective tube, and the compound is allowed to harden.

[0005] However, as described above, in the assembly of conventional cable intermediate splice structures, the shielding layer is wound around the rubber unit on-site, and this winding work of the shielding layer takes a long time because it is performed while supporting the two connected power cables.

[0006] Furthermore, when the shielding layer is tightly wound around the outer periphery of a rubber unit whose diameter has been expanded by a diameter expansion retainer, the expanded rubber unit will shrink in diameter when the diameter expansion retainer is pulled out of the rubber unit. As the rubber unit shrinks in diameter, the state of the shielding layer that was previously tightly attached to the rubber unit will be disrupted, and it will be necessary to rewind the shielding layer. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-37065 Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present disclosure is to provide a power cable intermediate connection unit and a power cable connection method that can easily form a shielding layer in a short time by pulling out a diameter expansion retaining material. [Means for solving the problem]

[0009] [1] A power cable intermediate connection unit for assembling a cable intermediate connection structure that connects the end of a first power cable and the end of a second power cable, the power cable intermediate connection unit comprising: a diameter expansion retaining member; a rubber unit into which the diameter expansion retaining member is inserted and whose diameter is expanded by the diameter expansion retaining member; and a shielding layer provided on the outer periphery of the rubber unit and composed of a plurality of shielding wires arranged at a distance from each other. [2] The power cable intermediate connection unit according to [1] above, wherein the diameter expansion and retention member is a spiral core. [3] An intermediate connection unit for a power cable as described in [1] or [2] above, wherein the plurality of shielding wires extend along the axial direction of the diameter expansion retaining material and are arranged around the circumferential direction of the diameter expansion retaining material. [4] The power cable intermediate connection unit according to [1] or [2] above, wherein the plurality of shielding wires are a braid wound in a spiral shape. [5] The power cable intermediate connection unit according to any one of the above [1] to [4], wherein one of the plurality of shielding wires has a terminal at one end. [6] The power cable intermediate connection unit according to any one of [1] to [5] above, further comprising at least one metal roll spring that covers the outer periphery of a portion of the shielding layer in an expanded state and is electrically connected to the shielding layer. [7] The power cable intermediate connection unit according to any one of [1] to [6] above, further comprising at least one resin pressing portion that covers the outer periphery of a portion of the shielding layer in an expanded diameter state. [8] The power cable intermediate connection unit according to [7] above, wherein the holding portion includes at least one of an elastic rubber band and a rubber net. [9] A method for connecting power cables, comprising: a step (step 1) of connecting a first cable conductor of a first power cable and a second cable conductor of a second power cable with a conductor connection part; and a step (step 2) of installing a rubber unit and a shielding layer on the outer periphery of the conductor connection part using the power cable intermediate connection unit described in any one of [1] to [8] above. [Effects of the Invention]

[0010] According to the present disclosure, it is possible to provide a power cable intermediate connection unit and a power cable connecting method that can easily form a shielding layer in a short time by pulling out a diameter expansion retaining material. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram showing an example of a power cable intermediate connection unit according to an embodiment. [Figure 2] FIG. 2 is a cross-sectional view taken along line AA in FIG. [Figure 3] FIG. 3 is a cross-sectional view taken along the line BB in FIG. [Figure 4] FIG. 4 is a schematic view showing a state after the diameter expansion holding member has been pulled out from the power cable intermediate connection unit shown in FIG. [Figure 5] FIG. 5 is a vertical cross-sectional view showing an example of a cable intermediate connection structure assembled using the power cable intermediate connection unit of the embodiment. [Figure 6] FIG. 6 is a schematic view showing another example of the power cable intermediate connection unit according to the embodiment. [Figure 7] FIG. 7 is a schematic view showing the state after the diameter expansion holding member has been pulled out from the power cable intermediate connection unit shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, a detailed description will be given based on an embodiment.

[0013] As a result of extensive research, the present inventors have focused on the configuration of the shielding layer, thereby facilitating the formation of the shielding layer by drawing out the diameter expansion holding material and shortening the formation time.

[0014] The power cable intermediate connection unit of the embodiment is a power cable intermediate connection unit for assembling a cable intermediate connection structure that connects an end of a first power cable and an end of a second power cable, and includes a diameter expansion retaining material, a rubber unit into which the diameter expansion retaining material is inserted and whose diameter is expanded by the diameter expansion retaining material, and a shielding layer provided on the outer periphery of the rubber unit and composed of a plurality of shielding wire materials arranged at a distance from each other.

[0015] Fig. 1 is a schematic diagram showing an example of a power cable intermediate connection unit of an embodiment. Fig. 2 is a cross-sectional view taken along line AA in Fig. 1. Fig. 3 is a cross-sectional view taken along line BB in Fig. 1. Fig. 4 is a schematic diagram showing a state after a diameter expansion retaining member has been withdrawn from the power cable intermediate connection unit shown in Fig. 1. Fig. 5 is a longitudinal cross-sectional view showing an example of a cable intermediate connection structure assembled using a power cable intermediate connection unit. Fig. 6 is a schematic diagram showing another example of a power cable intermediate connection unit of an embodiment. Fig. 7 is a schematic diagram showing a state after a diameter expansion retaining member has been withdrawn from the power cable intermediate connection unit shown in Fig. 6.

[0016] 1, 4, and 6 to 7, details of the rubber unit 3 are omitted. For convenience, the terminal 50, roll spring 60, and pressing portion 70 are omitted in Fig. 5. In Fig. 5, the first cable conductor 11a, first cable insulator 12a, first outer semiconductive layer 13a, first semiconductive tape layer 14a, first cable shielding layer 15a, and first cable sheath 16a of the first power cable 10a, and the second cable conductor 11b, second cable insulator 12b, second outer semiconductive layer 13b, second semiconductive tape layer 14b, second cable shielding layer 15b, and second cable sheath 16b of the second power cable 10b are shown in side views.

[0017] 1 to 5, the power cable intermediate connection unit 1 of this embodiment is a jig for assembling a cable intermediate connection structure 1a that connects an end of a first power cable 10a and an end of a second power cable 10b. The power cable intermediate connection unit 1 includes a diameter expansion retaining member 10, a rubber unit 3, and a shielding layer 4.

[0018] The diameter expansion retaining material 10 constituting the power cable intermediate connection unit 1 supports the rubber unit 3 from the inner peripheral side of the rubber unit 3 while maintaining the expanded diameter state of the rubber unit 3. The diameter expansion retaining material 10 has a hollow tubular shape, for example, a hollow cylindrical shape.

[0019] The inner diameter of the diameter expansion retaining material 10 is larger than the outer diameter of the end portions of the stepped-stripped first power cable 10a and second power cable 10b. If the inner diameter of the diameter expansion retaining material 10 is smaller than or the same as the outer diameter of the stepped-stripped end portions of the first power cable 10a and second power cable 10b, it will be difficult to pass the power cable intermediate connection unit 1 through the first power cable 10a and second power cable 10b when assembling the cable intermediate connection structure 1a for the power cables.

[0020] At the end of the first power cable 10a that has been subjected to the step-stripping process, the first cable conductor 11a, the first cable insulation 12a, the first outer semiconductive layer 13a, the first semiconductive tape layer 14a, and the first cable shielding layer 15a are exposed from the first cable sheath 16a, as shown in Fig. 5. Similarly, at the end of the second power cable 10b that has been subjected to the step-stripping process, the second cable conductor 11b, the second cable insulation 12b, the second outer semiconductive layer 13b, the second semiconductive tape layer 14b, and the second cable shielding layer 15b are exposed from the second cable sheath 16b.

[0021] When assembling the cable intermediate connection structure 1a, the diameter expansion holding material 10 is preferably an inner core or an expanding pipe so that it can be easily pulled out from the power cable intermediate connection unit 1. If the inner core is a spiral core, the diameter expansion holding material 10 can be pulled out even more easily.

[0022] The rubber unit 3 constituting the power cable intermediate connection unit 1 is expanded in diameter by a diameter expansion retaining material 10. The rubber unit 3 has a hollow tubular shape, for example, a hollow cylindrical shape. The diameter expansion retaining material 10 is inserted into the rubber unit 3. In this way, the diameter expansion retaining material 10 inserted into the rubber unit 3 allows the rubber unit 3 to maintain its expanded diameter state.

[0023] When assembling the cable intermediate joint structure 1a for power cables, the diameter expansion retaining member 10 is pulled out from the expanded rubber unit 3, thereby contracting the diameter of the rubber unit 3 and bringing the rubber unit 3 into close contact with the outer peripheries of the first power cable 10a and the second power cable 10b including the conductor connection portion 2, for example, the outer peripheries of the first cable insulator 12a, the first outer semiconductive layer 13a, the second cable insulator 12b, and the second outer semiconductive layer 13b. In this way, the restored force of the rubber unit 3 contracts the expanded rubber unit 3. To contract the expanded rubber unit 3, the rubber unit 3 has radial contractibility at room temperature, for example, in a temperature range of 0°C to 40°C.

[0024] The shielding layer 4 constituting the power cable intermediate connection unit 1 is made up of a plurality of shielding wires 40. The plurality of shielding wires 40 are provided on the outer periphery of the expanded rubber unit 3. The plurality of shielding wires 40 provided on the outer periphery of the expanded rubber unit 3 are spaced apart from one another. The shielding layer 4 is made of a highly conductive metal such as copper, copper alloy, aluminum, or aluminum alloy. Note that an adhesive (not shown) may be provided between the outer surface of the rubber unit 3 and the inner surface of the shielding layer 4 to temporarily secure the shielding layer 4 to the outer surface of the rubber unit 3.

[0025] 1, the multiple shielding wires 40 extend along the axial direction of the diameter expansion holding material 10 and are arranged around the circumferential direction of the diameter expansion holding material 10. For example, the multiple shielding wires 40 extending along the axial direction of the diameter expansion holding material 10 are arranged around the entire circumference of the diameter expansion holding material 10.

[0026] As shown in FIG. 6, the plurality of shielding wires 40 may be braided and wound in a spiral shape.

[0027] 1 and 6, the multiple shielding wires 40 provided on the outer periphery of the diameter-expanded rubber unit 3 are spaced apart from one another. When the multiple shielding wires 40 are spaced apart from one another, the side surfaces 40a of the shielding wires 40 extending along the longitudinal direction of the shielding wires 40 are not in close contact with one another. However, when the shielding wires 40 are spaced apart in this manner, the multiple shielding wires 40 may cross each other.

[0028] The shielding layer 4 is provided on the outer periphery of the rubber unit 3, which has been expanded in diameter. When assembling the cable intermediate joint structure 1a, the diameter of the rubber unit 3 is reduced by pulling out the diameter expansion retaining material 10 from the expanded rubber unit 3. At this time, as the rubber unit 3 reduces in diameter, the multiple shielding wires 40 that were spaced apart are brought into close contact with each other. In this way, the shielding layer 4 can be formed in a state in which the side surfaces 40a of the multiple shielding wires 40 are in close contact with each other. Because the state of the shielding layer 4 is not disturbed, there is no need to re-form the shielding layer 4. In this way, the shielding layer 4 can be easily formed in a short time by pulling out the diameter expansion retaining material 10.

[0029] On the other hand, if the multiple shielding wires 40 in the power cable intermediate connection unit 1 are arranged in close contact with each other without being spaced apart, the multiple shielding wires 40 that were previously arranged in close contact will randomly overlap as the rubber unit 3 shrinks in diameter, causing the state of the formed shielding layer 4 to become distorted. Depending on the state of the shielding layer 4, the shielding layer 4 may need to be formed again.

[0030] The spacing between the plurality of shielding wires 40 arranged at intervals is set appropriately depending on the diameter expansion rate of the rubber unit 3.

[0031] Furthermore, one of the multiple shielding wires 40 may have a terminal 50 at one end 41. The terminal 50 provided at one end 41 of one shielding wire 40 is connected to the protective tube 7 shown in Fig. 5. For convenience, Fig. 5 does not show the connection between the terminal 50 and the protective tube 7.

[0032] The terminal 50 is attached in advance to the shielding wire 40 of the power cable intermediate connection unit 1. Therefore, the task of attaching the terminal 50 to the shielding wire 40 is not required at the assembly site of the cable intermediate connection structure 1a.

[0033] The power cable intermediate connection unit 1 may further include at least one metal roll spring 60 that covers a portion of the outer periphery of the shielding layer 4 in an expanded state and is electrically connected to the shielding layer 4. The roll spring 60 is a cylindrical metal member. The expanded roll spring 60 covers the entire outer periphery of the shielding layer 4.

[0034] As shown in the figure, the roll spring 60 covers the outer periphery of a portion of the shielding layer 4 in the axial direction of the diameter expansion retaining material 10. Here, three roll springs 60 are arranged at predetermined intervals across the axial direction of the diameter expansion retaining material 10.

[0035] When assembling the cable intermediate joint structure 1a, the diameter expansion retaining member 10 is pulled out from the expanded rubber unit 3, thereby reducing the diameter of the rubber unit 3. At this time, as the rubber unit 3 reduces in diameter, the multiple shielding wires 40 are brought into close contact with each other, and the roll spring 60 supports the multiple shielding wires 40 from their outer surfaces and comes into close contact with the outer surfaces of all of the closely-contacted shielding wires 40. In this way, the multiple shielding wires 40 can be brought into close contact with each other, and the roll spring 60 can be attached to the outer surfaces of all of the shielding wires 40. All of the shielding wires 40 that make up the shielding layer 4 are reliably electrically connected via the roll spring 60.

[0036] The power cable intermediate connection unit 1 may further include at least one resin pressing portion 70 that covers a portion of the outer periphery of the shielding layer 4 in an expanded diameter state. The pressing portion 70 is annular. The expanded diameter pressing portion 70 covers the entire outer periphery of the shielding layer 4.

[0037] As shown in the figure, the pressing portion 70 covers the outer periphery of part of the shielding layer 4 in the axial direction of the diameter expansion holding material 10. Here, two pressing portions 70 are arranged at a predetermined interval across the axial direction of the diameter expansion holding material 10.

[0038] The retaining portion 70 in the expanded diameter state covers the shielding layer 4 from the outer periphery. The retaining portion 70 presses the multiple shielding wires 40 toward the outer periphery of the rubber unit 3. Therefore, the retaining portion 70 can further prevent the shielding wires 40 from coming off from the outer periphery of the rubber unit 3.

[0039] When the power cable intermediate connection unit 1 includes the pressing portion 70, the power cable intermediate connection unit 1 may or may not include the roll spring 60. When the power cable intermediate connection unit 1 includes the roll spring 60 and the pressing portion 70, as shown in the figure, the attachment positions of the roll spring 60 and the pressing portion 70 on the shielding layer 4 do not overlap but are separated from each other.

[0040] When assembling the cable intermediate joint structure 1a, the diameter expansion retaining member 10 is pulled out of the expanded rubber unit 3, thereby reducing the diameter of the rubber unit 3. At this time, as the rubber unit 3 reduces in diameter, the multiple shielding wires 40 are brought into close contact with each other, and the pressing portion 70 presses the multiple shielding wires 40 from the outer surface side. In this way, the pressing portion 70 further prevents the shielding wires 40 from falling, and multiple shielding wires 40 that are in close contact with each other can be formed.

[0041] When the power cable intermediate connection unit 1 is equipped with a roll spring 60 and a clamping portion 70, one end 41 of one shielding wire 40 and the terminal 50 provided at the one end 41 are not restrained by the roll spring 60 or the clamping portion 70, as shown in the figure.

[0042] The retaining portion 70 preferably includes at least one of a stretchable rubber band and a rubber net. When the retaining portion 70 is configured with a rubber band or a rubber net, the retaining portion 70 is easy to attach, and the state of the shielding wire 40 can be visually observed when assembling the cable middle joint structure 1a.

[0043] 5 is a longitudinal cross-sectional view showing an example of a cable intermediate connection structure 1a assembled using the power cable intermediate connection unit 1. The first power cable 10a has, from the center, a first cable conductor 11a, a first cable insulator 12a covering the outer periphery of the first cable conductor 11a, a first cable shielding layer 15a covering the outer periphery of the first cable insulator 12a, and a first cable sheath 16a covering the outer periphery of the first cable shielding layer 15a. An internal semiconductive layer (not shown) is provided on the inner periphery of the first cable insulator 12a. The outer periphery of the first cable insulator 12a is provided, from the inside, with a first external semiconductive layer 13a and a first semiconductive tape layer 14a.

[0044] Like the first power cable 10a, the second power cable 10b also has, from the center, a second cable conductor 11b, a second cable insulator 12b, a second cable shielding layer 15b, and a second cable sheath 16b. An inner semiconductive layer (not shown) is provided on the inner periphery of the second cable insulator 12b. A second outer semiconductive layer 13b and a second semiconductive tape layer 14b are provided on the outer periphery of the second cable insulator 12b, in that order from the inside.

[0045] The first cable conductor 11a and the second cable conductor 11b are made of a highly conductive metal such as copper, copper alloy, aluminum, or aluminum alloy. The first cable insulator 12a and the second cable insulator 12b are made of a highly electrically insulating resin such as cross-linked polyethylene. The inner semiconductive layer, the first outer semiconductive layer 13a and the second outer semiconductive layer 13b, and the first semiconductive tape layer 14a and the second semiconductive tape layer 14b are made of a semiconductive resin or the like. The first cable shielding layer 15a and the second cable shielding layer 15b are made of a highly conductive metal such as copper, copper alloy, aluminum, or aluminum alloy. The first cable sheath 16a and the second cable sheath 16b are made of a resin such as polyethylene or polyvinyl chloride.

[0046] The first power cable 10a and the second power cable 10b are, for example, CV cables (cross-linked polyethylene insulated vinyl sheath cables), and such first power cable 10a and second power cable 10b are suitable for use as high voltage cables and extra high voltage cables.

[0047] The cable intermediate joint 1a comprises, from the center outward, a conductor connection part 2, a rubber unit 3, a shielding layer 4, a protective layer 5, a compound part 6, and a protective tube 7. The conductor connection part 2 constituting the cable intermediate joint 1a connects an end of the first cable conductor 11a of the first power cable 10a and an end of the second cable conductor 11b of the second power cable 10b. For example, the cable intermediate joint 1a is generally symmetrical about its central axis, and at the connection part between the first cable conductor 11a and the second cable conductor 11b, it is also generally symmetrical about a direction perpendicular to the axial direction of the cable intermediate joint 1a.

[0048] The conductor connection portion 2 connects the end of the first cable conductor 11a and the end of the second cable conductor 11b, which are exposed by step-stripping the end portions of the first power cable 10a and the second power cable 10b. For example, the conductor connection portion 2 is cylindrical. By inserting the first power cable 10a into one end of the conductor connection portion 2 and the second power cable 10b into the other end of the conductor connection portion 2 and compressing the conductor connection portion 2, the conductor connection portion 2 electrically connects the first cable conductor 11a of the first power cable 10a and the second cable conductor 11b of the second power cable 10b.

[0049] From the viewpoint of high electrical conductivity and compressibility, the conductor connection portion 2 is preferably made of copper, a copper alloy, aluminum, or an aluminum alloy. A semiconductive tape layer or the like may be provided on the outer peripheral surface of the conductor connection portion 2 and the outer peripheral surfaces of the exposed first cable conductor 11a and second power cable 10b.

[0050] The rubber unit 3 constituting the cable intermediate joint structure 1a covers the outer periphery of the conductor connection portion 2. The rubber unit 3 is cylindrical and serves as the main insulating portion of the cable intermediate joint structure 1a. Here, the rubber unit 3 continuously covers the outer periphery from the first outer semiconductive layer 13a of the first power cable 10a to the second outer semiconductive layer 13b of the second power cable 10b. The rubber unit 3 is attached in an expanded state, covering the outer periphery of the first power cable 10a and the second power cable 10b, including the conductor connection portion 2. Therefore, the restoring force of the rubber unit 3 causes the inner periphery of the rubber unit 3 to adhere closely to the outer periphery, including the conductor connection portion 2.

[0051] The rubber unit 3 has a main insulating portion 31, a cylindrical inner semiconductive portion 32 provided on the inner circumferential portion of the center of the main insulating portion 31 in the axial direction of the cable intermediate connection structure 1a, end semiconductive portions 33 provided on both ends of the main insulating portion 31, and a cylindrical outer semiconductive portion 34 provided on the outer circumferential portion of the axial center of the main insulating portion 31.

[0052] The main insulating portion 31 of the rubber unit 3 covers the outer periphery from the first cable insulator 12a of the first power cable 10a to the second cable insulator 12b of the second power cable 10b. The main insulating portion 31 is made of rubber with high electrical insulation, preferably insulating silicone rubber or insulating ethylene propylene rubber.

[0053] The inner circumferential semiconductive portion 32 covers the outer periphery of the conductor connection portion 2. Each end semiconductive portion 33 is connected to the first outer semiconductive layer 13a and the second outer semiconductive layer 13b, respectively. A part of the main insulating portion 31 is interposed between each end semiconductive portion 33 and the outer circumferential semiconductive portion 34. The end semiconductive portion 33 and the outer circumferential semiconductive portion 34 are electrically insulated. The inner circumferential semiconductive portion 32, the end semiconductive portion 33, and the outer circumferential semiconductive portion 34 are made of semiconductive rubber, preferably semiconductive silicone rubber or semiconductive ethylene propylene rubber.

[0054] Furthermore, a pedestal spacer 36 is provided on each end of the rubber unit 3. The pedestal spacer 36 forms an inclined surface between the outer peripheral surface of the first outer semiconductive layer 13a or the second outer semiconductive layer 13b and the outer peripheral surface of the main insulating part 31. A semiconductive tape layer 35 is provided in the gap around the pedestal spacer 36.

[0055] The shielding layer 4 constituting the cable intermediate joint structure 1a covers the outer periphery of the rubber unit 3. The shielding layer 4 covering the rubber unit 3 connects the first cable shielding layer 15a of the first power cable 10a or the second cable shielding layer 15b of the second power cable 10b to the outer periphery semiconductive part 34 of the rubber unit 3.

[0056] The protective layer 5 that constitutes the cable intermediate joint structure 1a covers the outer periphery of the shielding layer 4. The protective layer 5 that covers the shielding layer 4 protects the shielding layer 4. The protective layer 5 is made of rubber with high electrical insulation properties, such as butyl rubber.

[0057] The resin compound part 6 that constitutes the cable intermediate joint structure 1a covers the outer periphery of the protective layer 5. The compound part 6 is preferably made of a thermosetting resin that has high heat dissipation and electrical insulation properties, and more preferably made of insulating silicone rubber, urethane resin, or insulating ethylene propylene rubber.

[0058] A protective tube 7 is attached to the outer periphery of the compound portion 6. The protective tube 7 is cylindrical and covers the outer periphery of the compound portion 6. Here, the protective tube 7 continuously covers the outer periphery from the first cable shielding layer 15a of the first power cable 10a to the second cable shielding layer 15b of the second power cable 10b.

[0059] Next, a method for connecting the power cables according to the embodiment will be described.

[0060] The power cable connecting method of the embodiment includes a step (step 1) of connecting a first cable conductor of a first power cable and a second cable conductor of a second power cable with a conductor connection portion, and a step (step 2) of installing a rubber unit and a shielding layer on the outer periphery of the conductor connection portion using the above-mentioned power cable intermediate connection unit.

[0061] In step 1, the first cable conductor 11a exposed from the end of the first power cable 10a and the second cable conductor 11b exposed from the end of the second power cable 10b are inserted into the conductor connection part 2, and the conductor connection part 2 is compressed to connect the first cable conductor 11a of the first power cable 10a and the second cable conductor 11b of the second power cable 10b.

[0062] At the end of the first power cable 10a, the first cable conductor 11a, the first cable insulator 12a, the first outer semiconductive layer 13a, the first semiconductive tape layer 14a, and the first cable shielding layer 15a are exposed from the first cable sheath 16a by step stripping. Similarly, at the end of the second power cable 10b, the second cable conductor 11b, the second cable insulator 12b, the second outer semiconductive layer 13b, the second semiconductive tape layer 14b, and the second cable shielding layer 15b are exposed from the second cable sheath 16b by step stripping.

[0063] Before connecting the first power cable 10a and the second power cable 10b, the power cable intermediate connection unit 1 is passed through the first power cable 10a or the second power cable 10b and is made to wait at a portion other than the end of the power cable.

[0064] In step 2, which is performed after step 1, a power cable intermediate connection unit 1 is used to install a rubber unit 3 and a shielding layer 4 on the outer periphery of the conductor connection portion 2, and the outer periphery of the conductor connection portion 2 is covered with the rubber unit 3. After the first power cable 10a and the second power cable 10b are connected with the conductor connection portion 2, the power cable intermediate connection unit 1 is moved to the outer periphery of the conductor connection portion 2. Next, the diameter expansion retaining member 10 is removed from the power cable intermediate connection unit 1. In this way, the rubber unit 3, which has been expanded, contracts in diameter due to its restoring force, and the rubber unit 3 comes into close contact with the outer periphery of the first power cable 10a and the second power cable 10b including the conductor connection portion 2, for example, the outer periphery of the first cable insulator 12a, the first outer semiconductive layer 13a, the second cable insulator 12b, and the second outer semiconductive layer 13b.

[0065] Furthermore, as the rubber unit 3 shrinks in diameter, the shielding wires 40 that were spaced apart come into close contact with each other. Therefore, by removing the diameter expansion and retaining member 10 from the power cable intermediate connection unit 1, the rubber unit 3 is attached to the outer periphery of the first power cable 10a and the second power cable 10b, each including the conductor connection portion 2, and the shielding layer 4 made up of the shielding wires 40 that are in close contact with each other is attached to the outer periphery of the rubber unit 3. In this way, by using the power cable intermediate connection unit 1, the first power cable 10a and the second power cable 10b are connected, and a cable intermediate connection structure for power cables that includes the rubber unit 3 and the shielding layer 4 can be easily assembled in a short amount of time.

[0066] The shielding wires 40 may be held in close contact with one another by roll springs 60 to ensure that all of the shielding wires 40 are electrically connected.

[0067] Furthermore, in order to electrically connect the end of the shielding wire 40 on the rubber unit 3 to the first cable shielding layer 15a of the first power cable 10a and the second cable shielding layer 15b of the second power cable 10b, the shielding wire 40 is wound, if necessary, so as to be in close contact with each other to form the shielding layer 4.

[0068] A terminal 50 provided at one end 41 of the shielding wire 40 is connected to the protective tube 7 .

[0069] After step 2, a protective layer 5, a compound part 6, and a protective tube 7 are attached as needed.

[0070] As described above, according to the embodiment of the power cable intermediate connection unit and the power cable connecting method, by focusing on the configuration of the shielding layer and arranging a plurality of shielding wires at intervals around the outer periphery of the rubber unit in an expanded diameter state, the shielding layer can be easily formed in a short time.

[0071] Although the embodiments have been described above, the present invention is not limited to the above embodiments, but includes all aspects encompassed by the concept and scope of the claims of the present disclosure, and can be modified in various ways within the scope of the present disclosure. [Explanation of symbols]

[0072] 1. Power cable intermediate connection unit 1a Cable intermediate joint structure 2 Conductor connection 3 Rubber Unit 4 Shielding layer 5 Protective layer 6 Compound section 7 Protection tube 10 Diameter expansion retainer 10a First power cable 10b Second power cable 11a First cable conductor 11b Second cable conductor 12a First cable insulator 12b Secondary cable insulator 13a First outer semiconducting layer 13b Second outer semiconducting layer 14a First semiconductive tape layer 14b Second semiconductive tape layer 15a First cable shielding layer 15b Second cable shielding layer 16a First cable sheath 16b Second cable sheath 31 Main insulation section 32 Inner circumference semiconductive part 33 Semiconductive end part 34 Semiconductive outer periphery 35 Semiconductive tape layer 36 Base spacer 40 Shielding wire 40a Side of shielding wire 41 One end of the shielding wire 50 terminals 60 roll spring 70 Presser foot

Claims

1. A power cable intermediate splice unit for assembling a cable intermediate splice structure that connects an end of a first power cable and an end of a second power cable, comprising: a diameter expansion holding material; a rubber unit having a diameter expansion retaining member inserted therein and expanded by the diameter expansion retaining member; a shielding layer provided on the outer periphery of the rubber unit and composed of a plurality of shielding wires spaced apart from each other; 1. A power cable intermediate connection unit comprising:

2. 2. The power cable intermediate connection unit according to claim 1, wherein the diameter expansion and retention member is a spiral core.

3. 2. The power cable intermediate connection unit according to claim 1, wherein the plurality of shielding wires extend along the axial direction of the diameter expansion holding member and are arranged around the circumferential direction of the diameter expansion holding member.

4. The power cable intermediate connection unit according to claim 1 , wherein the plurality of shielding wires are a braid wound in a spiral shape.

5. The power cable intermediate connection unit according to claim 1 , wherein one of the plurality of shielding wires has a terminal at one end.

6. The power cable intermediate connection unit according to claim 1 , further comprising at least one metallic roll spring that covers an outer periphery of a portion of the shielding layer in an expanded state and is electrically connected to the shielding layer.

7. The power cable intermediate connection unit according to claim 1 , further comprising at least one pressing portion made of resin and covering an outer periphery of a portion of the shielding layer in an expanded diameter state.

8. The power cable intermediate connection unit according to claim 7 , wherein the pressing portion includes at least one of an elastic rubber band and a rubber net.

9. a step (step 1) of connecting a first cable conductor of a first power cable and a second cable conductor of a second power cable by a conductor connection part; a step (step 2) of installing a rubber unit and a shielding layer around the outer periphery of the conductor connection part using the power cable intermediate connection unit according to any one of claims 1 to 8; 1. A power cable connecting method comprising:

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