Cable termination structure

Abstract

A cable termination structure is provided to mitigate stress caused by heat or other factors during cable expansion and contraction, while also mitigating the electric field in the cable termination portion and minimizing leakage of insulating fluid from the insulating tube. The termination structure 1 of the cable 2 comprises: an insulating tube 3 housing the termination portion 20 of the cable 2 and filled with an insulating fluid; a lower metal flange 4 having a through hole 40 for insertion of the termination portion 20; a metal cylinder 5, which, when the through hole 40 is closed, can slide relative to the lower flange 4 in response to the expansion and contraction of the cable 2; a sealing structure 6 sealing the upper end portion 5a of the metal cylinder 5 and the stripped portion of the outer semiconductive layer 23; a buffer layer 7 covering the stripped portion of the outer semiconductive layer 23 located further from the termination 2a than the sealing structure 6; and a metal layer 8 covering the outer surface of the buffer layer 7 and at least the upper end portion 5a of the metal cylinder 5; wherein the metal cylinder 5 and the lower flange 4 are grounded via a conductor 51.

Description

Technical Field

[0001] This invention relates to the terminal structure of a cable. Prior Technology

[0002] At the termination of high-voltage cables, where the conductor and outer semiconductive layer are exposed in a stepped manner at the front end, an insulating tube is provided to cover the exposed area of ​​the conductor and outer semiconductive layer. This insulating tube is filled with an insulating fluid. Furthermore, at the cable termination, to improve voltage withstand characteristics, termination treatment is required to prevent electric field concentration. As an example of such cable termination structure, a termination structure using a stress cone can be cited.

[0003] However, when a cable with such a terminal is energized, the cable is heated and expands thermally, causing it to elongate. This puts stress on the parts that seal the insulating fluid at the top and bottom of the insulating tube and on components such as the stress cone at the terminal, which may shorten the lifespan of these parts and components.

[0004] Regarding this point, as a terminal structure for cables using insulating tubes, for example, Patent Document 1 describes a cable terminal structure comprising: a cylindrical housing component disposed on the outer peripheral surface of the cable at a position corresponding to the through hole of the base portion; a sealing component such as an O-ring that seals the outer peripheral surface of the housing component and the inner peripheral surface of the through hole; and a protruding component that protrudes radially outward from a portion disposed within the insulating tube on the outer peripheral surface of the housing component.

[0005] In this terminal structure, the housing component is configured to maintain the interior of the insulating tube while following the expansion and contraction of the cable, and the lower end of the insulating tube is sealed by a base and a sealing component. Furthermore, near the upper end of the housing component, a sealing structure made of insulating material is provided to prevent the insulating fluid filled in the insulating tube from seeping into the cable side, and to cover at least from the outer surface of the conductive part of the stress cone to the outer surface of the housing component. [Previous Technical Documents] (Patent Documents)

[0006] Patent Document 1: Japanese Patent Application Publication No. 2020-182270 Summary of the Invention

[0007] [The problem the invention aims to solve]

[0008] However, in the terminal structure described in Patent Document 1, the housing component and the base are sealed by a sealing component such as an O-ring, and the housing component and the cable are sealed by a sealing structure made of insulating material. Since both are sealed by non-conductive materials, the stress cone and the housing component are not grounded. Therefore, in the terminal structure described in Patent Document 1, when the cable is energized, electric field disturbances occur due to the charge, which may shorten the lifespan of the terminal connection.

[0009] The purpose of this invention is to provide a cable termination structure that mitigates stress caused by heat and other factors that accompany cable expansion and contraction, while also mitigating the electric field in the cable termination section and making leakage of insulating fluid from the insulating tube less likely to occur. [Methods used to solve problems]

[0010] In order to achieve the above objectives, the essential structure of the present invention is as described below.

[0011] (1) A cable termination structure, the cable having at least a conductor, an insulating layer covering the conductor, and an outer semiconductive layer covering the insulating layer, the cable termination structure being a structure having a cable termination portion formed by stripping the outer semiconductive layer, the insulating layer, and the conductor in sequence towards the termination side of the cable, the cable termination structure being characterized by comprising: an insulating tube housing the aforementioned termination portion of the cable and filled with an insulating fluid; a lower metal flange having a through hole for inserting the aforementioned termination portion of the cable; and a metal cylinder. With the aforementioned through hole of the aforementioned lower flange portion closed, it can slide relative to the aforementioned lower flange portion in response to the extension and retraction of the aforementioned cable; the sealing structure portion seals the upper end of the aforementioned metal cylinder and the stripped portion of the outer semiconductive layer of the aforementioned cable corresponding to the upper end of the aforementioned metal cylinder; a conductive buffer layer covers the stripped portion of the aforementioned outer semiconductive layer located further to the terminal side than the aforementioned sealing structure portion; and a metal layer covers the outer surface of the aforementioned buffer layer and at least the upper end of the aforementioned metal cylinder; wherein the aforementioned metal cylinder and the aforementioned lower flange portion are grounded via a wire.

[0012] (2) The cable terminal structure as described in (1) above, wherein the aforementioned buffer layer is a single layer.

[0013] (3) The cable terminal structure as described in (1) or (2) above, wherein the aforementioned buffer layer is formed by wrapping a semiconductive strip around the stripped portion of the aforementioned outer semiconductive layer.

[0014] (4) The cable terminal structure as described in (3) above, wherein the gap at the upper end of the aforementioned buffer layer and the upper end of the aforementioned semiconductive strip is approximately parallel to the extension direction of the aforementioned cable.

[0015] (5) The cable termination structure as described in any one of (1) to (4) above, wherein the aforementioned metal layer is formed by winding a metal strip at least from the outer surface of the aforementioned buffer layer to the outer surface below the upper end of the aforementioned metal cylinder.

[0016] (6) The cable terminal structure as described in (5) above, wherein the aforementioned metal layer, after the aforementioned metal strip is wound from a position lower than the upper end position of the aforementioned metal layer until it is wound to the aforementioned upper end position, covers the winding start end of the aforementioned metal strip by winding it in the direction toward the upper end of the aforementioned metal cylinder.

[0017] (7) The terminal structure of the cable as described in (5) or (6) above, wherein the aforementioned metal layer is formed by winding a metal strip made of fine metal wires.

[0018] (8) The cable terminal structure as described in any one of (5) to (7) above, wherein the aforementioned metal layer has an overlapping winding structure in which the aforementioned metal strips are partially overlapped with each other, and the winding end of the aforementioned metal strips is located on the outer surface of the aforementioned metal cylinder.

[0019] (9) The cable terminal structure as described in any one of (5) to (8) above, wherein the aforementioned metal layer has a solder fixing portion that fixes at least one end of the winding start end and the winding end end of the aforementioned metal strip.

[0020] (10) The cable terminal structure as described in (9) above, wherein the aforementioned solder fixing portion exists at a plurality of positions on the aforementioned metal layer at intervals in the extension direction of the aforementioned cable.

[0021] (11) The terminal structure of the cable as described in any one of (1) to (10) above, wherein the aforementioned metal layer forms the outermost layer of the aforementioned terminal portion of the cable.

[0022] (12) A cable termination structure, the cable having at least a conductor, an insulating layer covering the conductor, and an outer semiconductive layer covering the insulating layer, the cable termination structure being a structure having a cable termination portion formed by stripping the outer semiconductive layer, the insulating layer, and the conductor in sequence towards the termination side of the cable, the cable termination structure being characterized by comprising: an insulating tube housing the aforementioned termination portion of the cable and filled with an insulating fluid; a lower metal flange having a through hole for inserting the aforementioned termination portion of the cable; and a metal cylinder for inserting the aforementioned lower flange... With the aforementioned through hole closed, the lower flange portion can slide relative to the aforementioned lower flange portion in response to the extension and retraction of the aforementioned cable; the sealing structure portion seals the upper end of the aforementioned metal cylinder and the stripped portion of the outer semiconductive layer of the aforementioned cable corresponding to the upper end of the aforementioned metal cylinder; the conductive buffer layer covers the stripped portion of the aforementioned outer semiconductive layer located further to the terminal side than the aforementioned sealing structure portion; and the stress cone is provided at the boundary between the insulation layer and the outer semiconductive layer of the aforementioned cable, and is composed of an insulation portion and a semiconductive portion; wherein, the semiconductive portion of the aforementioned stress cone and the aforementioned lower flange portion are grounded by a wire. [Effects of the Invention]

[0023] According to the present invention, a cable termination structure can be provided that alleviates the stress caused by the expansion and contraction of the cable due to heat, etc., while also alleviating the electric field in the cable termination portion, and making it difficult for the insulating fluid to leak from the insulating tube. Simple Explanation of the Diagram

[0024] Figure 1(a) is a schematic longitudinal sectional view showing the terminal structure of the cable according to the first embodiment of the present invention; Figure 1(b) is an enlarged view of the portion enclosed by a frame with a dotted chain line in Figure 1(a). Figure 2 is a diagram showing the cable terminal structure of the first embodiment of the present invention after removing the insulating tube and metal layer, and in a manner that can be understood as having a buffer layer formed by winding a semiconductive strip. Figure 3 is a diagram showing the cable terminal structure of the first embodiment of the present invention with the insulation tube and the like removed, and in a way that it can be understood that a metal layer has been formed by winding a metal strip. Figure 4(a) is a schematic longitudinal sectional view of the cable terminal structure according to the second embodiment of the present invention; Figure 4(b) is an enlarged view of the portion enclosed by a dotted chain line in Figure 4(a). Figure 5(a) is a schematic longitudinal sectional view of the cable terminal structure according to the third embodiment of the present invention; Figure 5(b) is an enlarged view of the portion enclosed by a frame with a dotted chain line in Figure 5(a). Implementation

[0025] Hereinafter, specific embodiments of the present invention will be described in detail with reference to the accompanying drawings. Furthermore, the present invention is not limited to the following embodiments, and various modifications can be made without altering the spirit of the invention.

[0026] [First Implementation] Figure 1(a) is a schematic longitudinal sectional view showing the terminal structure of the cable according to the first embodiment of the present invention; Figure 1(b) is an enlarged view of the portion enclosed by the frame of a dotted chain line in Figure 1(a). Figure 2 shows the terminal structure of the cable according to the first embodiment of the present invention with the insulation tube and metal layer removed, in a manner that allows it to be understood that a buffer layer has been formed by winding a semi-conductive strip. Figure 3 shows the terminal structure of the cable according to the first embodiment of the present invention with the insulation tube removed, in a manner that allows it to be understood that a metal layer has been formed by winding a metal strip.

[0027] As shown in Figure 1, the cable 2 has at least a conductor 21, an insulation layer 22 covering the conductor 21, and an outer semiconductive layer 23 covering the insulation layer 22. The terminal structure 1 of the cable 2 of the present invention is a structure with a terminal portion 20 of the cable 2 formed by stripping the outer semiconductive layer 23, the insulation layer 22, and the conductor 21 in sequence towards the terminal 2a side of the cable 2. The terminal structure 1 includes: an insulating tube 3 that houses the terminal portion 20 of the cable 2 and is filled with an insulating fluid; a lower flange portion 4 made of metal with a through hole 40 for inserting the terminal portion 20 of the cable 2; and a metal cylinder. 5. With the through hole 40 of the lower flange portion 4 closed, it can slide relative to the lower flange portion 4 in response to the extension and retraction of the cable 2; the sealing structure portion 6 seals the upper end portion 5a of the metal cylinder 5 and the stripped portion of the outer semiconductive layer 23 of the cable 2 corresponding to the upper end portion 5a of the metal cylinder 5; the conductive buffer layer 7 covers the stripped portion of the outer semiconductive layer 23 located on the side closer to the terminal 2a than the sealing structure portion 6; and the metal layer 8 covers the outer surface of the buffer layer 7 and at least the upper end portion 5a of the metal cylinder 5; wherein the metal cylinder 5 and the lower flange portion 4 are grounded via the wire 51.

[0028] In the terminal structure 1 of this embodiment, since the metal cylinder 5 slides relative to the lower flange 4 in response to the expansion and contraction of the cable 2, the stress applied to the terminal structure 1 due to the expansion and contraction of the cable can be mitigated. Furthermore, a conductive buffer layer 7 is provided to cover the stripped portion of the outer semiconductive layer 23, and a metal layer 8 is provided to cover the outer surface of the buffer layer 7 and at least the upper end portion 5a of the metal cylinder 5. The metal cylinder 5 and the lower flange 4 are further grounded by a wire 51. Thus, the buffer layer 7 provided on the outer semiconductive layer 23 is grounded, thereby mitigating the electric field in the terminal portion 20 of the cable 2. Simultaneously, the inner surface of the through hole 40 of the lower flange 4 of the insulating tube 3 is sealed by the outer surface of the metal cylinder 5, and the upper end portion 5a of the metal cylinder 5 and the outer semiconductive layer 23 of the cable 2 located inside it are sealed by the sealing structure 6. Therefore, even if the metal cylinder 5 slides relative to the lower flange 4, leakage of insulating fluid from the insulating tube 3 is unlikely to occur.

[0029] Therefore, based on this terminal structure 1, a terminal structure for a cable 2 can be provided, which can alleviate the stress caused by the expansion and contraction of the cable 2 due to heat, etc., while also alleviating the electric field in the terminal portion 20 of the cable 2, and making it difficult for the insulating fluid to leak from the insulating tube 3.

[0030] The terminal structure 1 of the cable 2 in this embodiment, as shown in FIG1, includes a cable 2, an insulating tube 3, a lower flange portion 4, a metal cylinder 5, a sealing structure portion 6, a buffer layer 7, and a metal layer 8.

[0031] (cable) The cable 2 has at least a conductor 21, an insulation layer 22 covering the conductor 21, and an outer semiconducting layer 23 covering the insulation layer 22. Here, the cable 2 may also have a shielding layer 24 formed by copper tape or the like and electrically grounded on the outer surface of the outer semiconducting layer 23. Furthermore, the cable 2 may also have a cable sheath 25 forming the outermost layer on the outer surfaces of the outer semiconducting layer 23 and the shielding layer 24. Moreover, the cable 2 may also have an inner semiconducting layer (not shown) between the conductor 21 and the insulation layer 22.

[0032] Here, cable 2 can be a CV cable, for example, a high-voltage cable or an ultra-high-voltage cable that transmits power at a voltage of 66kV or higher. In particular, cable 2 can also include ultra-high-voltage cables with a voltage of 400kV or higher and 500kV or higher.

[0033] The conductor 21 of cable 2 is typically located in the center of cable 2, serving as the path for electrical current. The insulation layer 22 is a layer that covers the conductor 21 and electrically insulates the conductor 21 from the external semiconducting layer 23, which will be described later. Furthermore, the external semiconducting layer 23 is a layer constructed by covering the insulation layer 22, shielding the electric field generated when cable 2 is energized.

[0034] As the material for conductor 21, conductive metals such as copper or aluminum can be used. As the material for insulating layer 22, electrically insulating resins such as cross-linked polyethylene can be used. As the materials for the outer semiconductive layer 23 and the inner semiconductive layer, semiconductive resins can be used. As the shielding layer 24, strips or braids of conductive metals such as copper and aluminum can be used. As the material for cable sheath 25, polyethylene resin, for example, can be used.

[0035] The cable 2 has a terminal portion 20, which is formed by stripping the outer semiconductive layer 23, the insulation layer 22, and the conductor 21 in sequence, facing the terminal 2a side of the cable 2. This makes it easier to connect the conductor 21 to conductive components such as the conductor lead-out rod 33 located inside the insulating tube 3. At the same time, when the buffer layer 7 is used to cover the terminal portion 20 of the cable 2 (described later), the buffer layer 7 can be easily electrically connected to the outer semiconductive layer 23 while ensuring electrical insulation between the conductor 21 and the outer semiconductive layer 23.

[0036] The material of cable 2 is not particularly limited and can be determined according to the necessary current carrying capacity, rated voltage, and the heat that may occur in the terminal structure 1 of cable 2.

[0037] (Insulating tube) The insulating tube 3 houses the terminal portion 20 of the cable 2 and is filled with an insulating fluid. In this way, the stripped portions of the conductor 21, insulation layer 22, and outer semiconducting layer 23 constituting the terminal portion 20 of the cable 2 are covered by the insulating tube 3 and filled with insulating fluid, thereby protecting the terminal portion 20 of the conductor 21.

[0038] The material of the insulating tube 3 can be any insulating material, and there are no particular limitations. For example, in addition to ceramics and porcelain, glass, and rubber, plastics such as fiber-reinforced plastic (FRP) can also be used. As an example of the insulating tube 3, the insulating tube shown in FIG1 can be used, which is constructed by forming a hollow cylindrical frame 31 made of fiber-reinforced plastic (FRP), and is covered by a rubber or plastic corrugated outer sleeve 32.

[0039] The insulating tube 3 forms the upper conductor fixing part 34 and the lower flange part 4, which will be described later, and also forms the internal space S, which is filled with an insulating fluid. Here, the insulating fluid filling the internal space S is not particularly limited; for example, it can be an insulating oil such as silicone oil, an insulating gas such as SF6 (sulfur hexafluoride) gas, etc. To prevent leakage of the insulating fluid from the insulating tube 3, the upper opening 31a and the lower opening 31b of the frame 31 of the insulating tube 3 are respectively closed.

[0040] (Upper conductor fixing part) The terminal structure 1 can also have an upper conductor fixing part 34 in a manner that closes the opening 31a on the upper side of the frame 31 of the cylindrical insulating tube 3. This upper conductor fixing part 34 can be used to install a conductive conductor lead-out rod 33. In this case, the conductor lead-out rod 33 is configured such that the terminal 2a of the conductor 21 is fixed and simultaneously connected to the outside of the insulating tube 3 (the upper side of FIG. 1).

[0041] Here, on one side (the lower side of FIG. 1), the conductor lead-out rod 33 has the terminal 2a of the conductor 21 fixed by compression connection. On the other side (the upper side of FIG. 1), the conductor lead-out rod 33 extends from the upper conductor fixing part 34 to the outside of the insulating tube 3. Since the conductor lead-out rod 33 is fixed to the upper conductor fixing part 34, the conductor 21 is fixed to the insulating tube 3 via the conductor lead-out rod 33.

[0042] The upper conductor fixing part 34 is constructed, for example, by a plate-shaped component through which the conductor lead-out rod 33 is inserted, and is fixed to the insulating tube 3 by connecting components such as screws. Furthermore, the portion of the upper conductor fixing part 34 through which the conductor lead-out rod 33 is inserted and the portion between the upper conductor fixing part 34 and the frame 31 of the insulating tube 3 are constructed in a manner that prevents leakage of insulating fluid; therefore, it is preferable to provide sealing components in these portions.

[0043] Furthermore, the terminal structure 1 may not have a separate upper conductor fixing part 34, for example, it may be integrally formed with the insulating tube 3.

[0044] (Lower flange portion) The lower flange 4 is provided in such a way that it closes the opening 31b on the lower side of the frame 31 of the cylindrical insulating tube 3. The lower flange 4 has a through hole 40 for inserting a cable 2. The cable 2 terminal structure 1 of this embodiment has a metal lower flange 4, which has a through hole 40 for inserting the terminal portion 20 of the cable 2.

[0045] Here, the lower flange portion 4 is fixed to the inner or outer circumference of the insulating tube 3, and includes: a cylindrical portion 41 fixed in such a way as to close the opening 31b on the lower side of the insulating tube 3, and a flange portion 42 extending radially inward and outward from the cylindrical portion 41. The portion of the flange portion 42 extending radially outward from the cylindrical portion 41 is fixed to a support bracket 43 (not shown) provided on a support frame platform by means of a connecting member such as screws.

[0046] The lower flange 4 is made of metal and is electrically grounded by a grounding wire (not shown) provided on the lower flange 4. In this way, when the metal cylinder 5, to which the external semiconductive layer 23 is electrically connected, is connected to the lower flange 4 by a wire 51, the metal cylinder 5 connected to the lower flange 4 can be grounded through the wire 51.

[0047] The shape of the through hole 40 in the lower flange portion 4 is not particularly limited as long as it allows the metal cylinder 5 to be inserted. However, based on the viewpoint of making it more difficult for the insulating fluid to leak from the insulating tube 3, and at the same time making the sliding movement of the metal cylinder 5 relative to the lower flange portion 4 in the vertical direction smoother, it is preferable to have a shape that is approximately the same as the outer shape of the metal cylinder 5.

[0048] Furthermore, the lower flange portion 4 can also be constructed by extending the metal shell 44. In this way, the direction of cable 2 extension is guided downwards by the metal shell 44. Therefore, an anti-corrosion layer 26 can be easily formed on the lower side of the insulating tube 3.

[0049] Furthermore, the term "metallic" in this disclosure includes not only components made of metal, but also components made of alloys.

[0050] (Metal cylinder) The metal cylinder 5, with the through hole 40 of the lower flange portion 4 closed, is configured to slide relative to the lower flange portion 4 in response to the expansion and contraction of the cable 2. In this way, with the thermal expansion of the outer jacket 32, the metal cylinder 5 slides relative to the lower flange portion 4 in the vertical direction. Therefore, even if the outer jacket 32 ​​of the insulating tube 3 thermally expands due to heat generated when the cable 2 is energized, the internal structure of the insulating tube 3, apart from the frictional force with the insulating fluid, can suppress the generation of forces acting in the vertical direction, such as resistance forces.

[0051] Here, the outer surface of the metal cylinder 5 is formed in a manner close to the inner surface of the through hole 40, and the through hole 40 is sealed by an O-ring or similar shaft seal. Furthermore, a cable 2 is inserted into the metal cylinder 5, and the upper end 5a of the metal cylinder 5 and the stripped portion of the outer semiconductive layer 23 of the cable 2 are sealed by the sealing structure 6 described later.

[0052] The metal cylinder 5 is made of metal, such as aluminum, stainless steel, copper, and brass.

[0053] Ideally, the inner and outer diameters of the metal cylinder 5 should be equal throughout, based on the viewpoint of ensuring smooth sliding movement relative to the lower flange 4. However, to prevent detachment from the through hole 40 of the lower flange 4, the outer diameter of the upper or lower end of the metal cylinder 5 may be locally increased. Furthermore, to prevent detachment from the through hole 40 of the lower flange 4, a stop (not shown) may be provided on the outer surface of the upper or lower end of the metal cylinder 5 to define the range of sliding movement of the metal cylinder 5.

[0054] (Sealing structure section) The sealing structure 6 seals the upper end 5a of the metal cylinder 5 and the stripped portion of the outer semiconductive layer 23 of the cable 2 corresponding to the upper end 5a of the metal cylinder 5. This prevents the infiltration of insulating fluid into the inner part of the metal cylinder 5, thus making leakage of insulating fluid from the insulating tube 3 through the metal cylinder 5 less likely.

[0055] The sealing structure 6 is preferably formed to cover the outer surface of the upper end portion 5a of the metal cylinder 5, and the outer surface of the metal cylinder 5 located below it is not covered by the sealing structure 6. In this way, in the area of ​​the outer surface of the metal cylinder 5 that is not covered by the sealing structure 6, since the outer surface of the metal cylinder 5 is in contact with the inner surface of the metal layer 8 (described later), the metal layer 8, the buffer layer 7 connected to the metal layer 8, and the outer semiconductive layer 23 can be grounded through the metal cylinder 5 connected to the lower flange portion 4.

[0056] The sealing structure 6 is preferably constructed of a material capable of seamlessly covering both sides of components with different outer diameters, thereby seamlessly covering both the outer surface of the metal cylinder 5 and the outer surface of the peeled portion of the outer semiconductive layer 23. Examples of such materials include self-adhesive tape and heat shrink tubing.

[0057] (Buffer layer) The buffer layer 7 is made of a conductive material and is provided to cover the stripped portion of the outer semiconductive layer 23 located further from the terminal 2a than the sealing structure portion 6. This mitigates the electric field concentration in the stripped portion of the outer semiconductive layer 23 located further from the terminal 2a than the sealing structure portion 6. Furthermore, since the buffer layer 7 is electrically connected to the lower flange portion 4 and grounded via the metal layer 8 (described later), the voltage withstand characteristics of the terminal portion 20 of the cable 2 are improved.

[0058] In particular, from the viewpoint of further improving the mitigation effect of electric field concentration in the peeled portion of the outer semiconductive layer 23, the buffer layer 7 preferably covers the peeled portion of the outer semiconductive layer 23 located from the position adjacent to the lower end 9a of the stress cone 9 (described later) to the upper end of the sealing structure portion 6.

[0059] As shown in FIG2, the buffer layer 7 is preferably a semiconductive strip layer 71 formed by winding a semiconductive strip at the peeling portion of the outer semiconductive layer 23. This allows the buffer layer 7 to be easily formed at the peeling portion of the outer semiconductive layer 23. Alternatively, the buffer layer 7 can also be formed using a heat-shrinkable tube or the like.

[0060] Furthermore, from the viewpoint of preventing air bubbles from forming inside the buffer layer 7, it is preferable that the buffer layer 7 is a single layer. In particular, when the buffer layer 7 is constructed by means of a semiconductive strip layer 71, the semiconductive strip layer 71 is preferably constructed by means of a single layer of semiconductive strip. Here, as a method for forming the semiconductive strip layer 71 by winding the single layer of semiconductive strip constituting the buffer layer 7 onto the peeled portion of the outer semiconductive layer 23, in addition to the gap winding method shown in FIG2, which winds the semiconductive strip without overlapping and with gaps, a butt winding method that winds the semiconductive strip without overlapping and without gaps can also be cited. In particular, in the gap winding method of winding semiconductive tape with a gap, from the viewpoint of preventing interference between the metal tape constituting the metal layer 8 (described later) and the outer semiconductive layer 23 of the cable 2, when the thickness of the semiconductive tape is about 0.5 mm or more and 1.0 mm or less, the buffer layer 7 is preferably formed by providing a gap of 5 mm or less along the extension direction X of the cable 2 and by winding the semiconductive tape layer 71.

[0061] When the buffer layer 7 is constructed using a semiconductive strip layer 71, the upper end 7a of the buffer layer 7, with its upper end slit 7b of the semiconductive strip, as shown in FIG. 2, is preferably approximately parallel to the extension direction X of the cable 2. In this case, the upper end 7a of the buffer layer 7, independently of the portion further down, at the stripping point of the outer semiconductive layer 23, is wound laterally (towards the direction of the cut line when cut perpendicularly to the extension direction X). This increases the adhesion area of ​​the semiconductive strip in the upper end 7a of the buffer layer 7, making the formed semiconductive strip layer 71 difficult to peel off. Furthermore, the increased adhesion force on the outer semiconductive layer 23 generated by the semiconductive strip layer 71 in the upper end 7a of the buffer layer 7 suppresses the infiltration of insulating fluid into the inner portion of the buffer layer 7. On the other hand, the lower portion of the buffer layer 7 is wound at an angle relative to the extension direction X of the cable 2, thereby efficiently forming the semiconductive strip layer 71.

[0062] As the material for the buffer layer 7, a conductive material can be used, such as a resin mixed with conductive carbon powder. In particular, by using resin to form the buffer layer 7, the buffer layer 7 can easily follow the thermal expansion of the outer semiconductive layer 23, etc., when the cable 2 is energized.

[0063] (Metal layer) As shown in FIG. 1, the metal layer 8 is provided in such a way that it covers the outer surface of the buffer layer 7 and at least the upper end portion 5a of the metal cylinder 5. This improves the voltage withstand characteristics of the terminal portion 20 of the cable 2 because the buffer layer 7 is electrically connected to the lower flange portion 4 and grounded via the metal cylinder 5. At this time, the sealing structure portion 6 is covered on the outside by the metal layer 8. Here, the metal layer 8 only needs to be provided in a way that covers at least a portion of the outer surface of the buffer layer 7 and at least the upper end portion 5a of the metal cylinder 5; for example, it can be wound along the extension direction X of the cable 2 at intervals to cover a portion of the outer surface of the buffer layer 7. Alternatively, the metal layer 8 can be provided in a way that covers the entire outer surface of the buffer layer 7 and at least the upper end portion 5a of the metal cylinder 5.

[0064] At this time, the metal layer 8 is preferably provided at least from the outer surface of the buffer layer 7 to the outer surface that is lower than the upper end 5a of the metal cylinder 5. The metal layer 8 is preferably provided lower than the position adjacent to the lower end 9a of the stress cone 9 (described later). Furthermore, from the viewpoint of reliably implementing the provision of the semi-conductive portion 92 of the stress cone 9, the metal layer 8 is preferably provided in a manner that engages with the lower end 9b of the semi-conductive portion 92 of the stress cone 9.

[0065] Here, the metal layer 8 is preferably a metal strip layer 81 formed by winding a metal strip. By using the metal strip layer 81 to form the metal layer 8, the metal layer 8 can be easily formed on the outer surface of the buffer layer 7, the sealing structure part 6, and the metal cylinder 5.

[0066] In particular, the metal layer 8 is preferably formed by winding a metal strip made of fine metal wires to form a metal strip layer 81. By using a metal strip made of fine metal wires, the clamping force on the buffer layer 7 generated by the metal strip layer 81 is enhanced, thereby improving the contact condition between the metal layer 8 and the buffer layer 7. Furthermore, by using a metal strip made of fine metal wires, even if air bubbles enter the inner surface of the metal layer 8 during the assembly of the terminal structure 1, the air bubbles are easily removed from between the fine metal wires constituting the metal layer 8. Therefore, it is particularly effective in suppressing local discharge in the high electric field region near the stress cone 9, resulting in improved insulation performance of the terminal structure 1.

[0067] When the metal layer 8 includes a metal strip layer 81, the metal layer 8 preferably has an overlapping winding structure in which the metal strips are wound together with partial overlap, and the winding end 81b of the metal strip is located on the outer surface of the metal cylinder 5. In particular, the metal strip layer 81 has an overlapping winding structure, thereby making it difficult for gaps to form in the metal layer 8 even if the cable 2 expands and contracts due to heat during energization, thus improving the shielding performance of the terminal structure 1 of the cable 2.

[0068] Furthermore, when the metal layer 8 has a metal strip layer 81, it is preferable that, as shown in FIG3, the metal strip is wound from a position lower than the upper end of the metal layer 8 until it reaches the upper end position, and then wound towards the upper end 5a of the metal cylinder 5 to cover the starting end 81a of the winding of the metal strip. At this time, the metal strip forming the metal strip layer 81 preferably starts from the outer surface of the buffer layer 7 located lower than the lower end 9a of the stress cone 9, and is wound upwards. After completely covering the upper end 7a of the buffer layer 7, it is reversed downwards, covering the end of the metal strip that started winding while passing through the outer surfaces of the buffer layer 7 and the sealing structure portion 6, and ending the winding on the metal surface of the metal cylinder 5 where the sealing structure portion 6 is not formed. By winding the metal strip in this manner, it is difficult to peel off the end of the metal strip.

[0069] Preferably, the metal layer 8 has a solder-attaching portion 82 on its outer surface. In particular, when the metal layer 8 is formed by a metal strip layer 81, the metal layer 8 preferably has a solder-attaching portion 82 that attaches at least one of the winding start end 81a and winding end end 81b of the metal strip. In this way, since the end of the metal strip is attached to the metal surface of the adjacent metal strip and metal cylinder 5 by means of the solder-attaching portion 82, the end of the metal strip is difficult to peel off.

[0070] Here, the solder fixing part 82 can also be formed on the outer surface of the buffer layer 7 from the viewpoint of reducing thermal stress when the cable 2 is energized. The solder fixing part 82 can also be used to fix the starting end 81a of the metal strip winding to the outer surface of the buffer layer 7.

[0071] Furthermore, the solder adherence portions 82 are preferably present at multiple locations on the metal layer 8 at intervals L along the extension direction X of the cable 2. In particular, by having multiple solder adherence portions 82 at multiple locations on the metal layer 8, the metal layer 8 can be made more difficult to peel off. Here, the interval L of the solder adherence portions 82 is not particularly limited, for example, it can be set in the range of 20 mm or more and 100 mm or less.

[0072] The metal layer 8 is preferably the outermost layer in the terminal portion 20 of the cable 2 after the insulation tube 3 has been removed. In this way, when the terminal structure 1 is assembled, even if air bubbles enter the inner surface of the metal layer 8, the air bubbles can be easily removed from the inner surface of the metal layer 8. Therefore, it is particularly effective to suppress the partial discharge of the high electric field near the stress cone 9, thereby improving the insulation performance of the terminal structure 1.

[0073] (Stress cone) In this embodiment, the termination structure 1 of the cable 2 can also be terminated at the boundary between the insulation layer 22 and the outer semiconductive layer 23 without causing electric field concentration. Therefore, as shown in FIG1, the termination structure 1 of this embodiment can have a stress cone 9 composed of an insulating part 91 and a semiconductive part 92 at the boundary between the insulation layer 22 and the outer semiconductive layer 23.

[0074] Here, as an example of stress cone 9, a stress cone can be described as follows: a cylindrical semiconducting portion 92, made of a semiconducting material, which is closely attached to and covers the outer surface of the outer semiconducting layer 23 of the cable 2; and a cylindrical insulating portion 91, made of an insulating material, which is closely attached to and covers at least the portion from the outer surface of the semiconducting portion 92 to the outer surface of the insulating layer 22. By providing such a stress cone 9, the electric field concentration in the stripped portion of the outer semiconducting layer 23 is mitigated by the semiconducting portion 92, thereby improving the withstand voltage characteristics of the terminal portion 20 of the cable 2.

[0075] (wire) In this embodiment, the terminal structure 1 of the cable 2 has a grounding wire 51 connected between the metal cylinder 5 and the lower flange 4. At this time, the metal cylinder 5 and the lower flange 4 are grounded via the grounding wire 51. Thus, the metal cylinder 5 is connected to the grounded lower flange 4 via the grounding wire 51, and simultaneously, the metal cylinder 5 is connected to the metal layer 8. Furthermore, since the metal layer 8 is connected to the buffer layer 7 already provided on the outer semiconductive layer 23 of the cable 2, the outer semiconductive layer 23 of the cable 2 and the buffer layer 7 provided on the outer semiconductive layer 23 can be grounded.

[0076] As for the material of the conductor 51, conductive metals can be cited as examples, and more specifically, copper and aluminum can be cited as examples. Furthermore, the conductor 51 can be a single wire, or, from the point of view of ease of operation, a braided wire.

[0077] The length of the conductor 51 is preferably longer than the straight-line distance between the connection points of the conductor 51 and the lower flange 4 when the cable 2 is energized and extended. This allows the length of the conductor 51 connecting the metal cylinder 5 and the lower flange 4 to be adjusted to a length that does not impede the sliding movement of the metal cylinder 5 relative to the lower flange 4.

[0078] (other) In this embodiment, at least the stripped portions of the shielding layer 24 and cable sheath 25 of the cable 2 located on the lower side of the lower flange 4 can also be covered by the anti-corrosion layer 26. Here, the anti-corrosion layer 26 can be made of epoxy resin, for example. The epoxy resin can be impregnated in glass tape or the like, and the glass tape or the like can be wound around the stripped portions of the shielding layer 24 and cable sheath 25 of the cable 2. Furthermore, the anti-corrosion layer 26 may further have a fastening layer (not shown) made of heat shrink tubing.

[0079] [Second Implementation] Figure 4(a) is a schematic longitudinal sectional view showing the terminal structure of the cable according to the second embodiment of the present invention; Figure 4(b) is an enlarged view of the portion enclosed by a dotted chain line in Figure 4(a). Furthermore, in the following description, the same components as those in the first embodiment described above will be marked with the same symbols and their descriptions will be omitted or simplified; the main focus will be on the differences.

[0080] In the terminal structure 1 of cable 2 shown in Figure 1, the metal layer 8 is shown as the outermost layer (after removing the insulating tube 3) forming the terminal portion 20 of cable 2, but it is not limited to this form. For example, in the terminal structure 1A shown in Figure 4, a metal wire 83, such as a flat braided copper wire with a larger cross-sectional area than the metal wire, can be arranged on the outer surface of the metal layer 8, which has a metal strip layer 81 formed by winding a metal strip made of metal wire. By arranging the metal wire 83 in this way, when a large current passes through the metal layer 8 during grounding tests, the current can continue to pass through the cable 2 without breaking the metal wire of the metal strip layer 81. In this case, the range of the location of the metal wire 83 is preferably from the position corresponding to the upper end 7a of the buffer layer 7 to the position where the metal surface of the metal tube 5 is exposed. Furthermore, the metal wire 83 can be joined to the surface of the metal layer 8 along the extension direction X of cable 2, or it can be wound on the surface of the metal layer 8 at an angle relative to the extension direction X of cable 2. The end of the metal wire 83 can be joined to the metal layer 8 by well-known means such as welding.

[0081] [Third Implementation] Figure 5(a) is a schematic longitudinal sectional view showing the terminal structure of the cable according to the third embodiment of the present invention; Figure 5(b) is an enlarged view of the portion enclosed by a frame with a dotted chain in Figure 5(a). Furthermore, in the following description, the same components as those in the first or second embodiment described above will be marked with the same symbols and their descriptions will be omitted or simplified, and the differences will be mainly described.

[0082] In the terminal structure 1 of cable 2 in Figure 1, a form is shown that has a metal layer 8 covering the outer surface of the buffer layer 7 and at least the upper end 5a of the metal cylinder 5, but it is not limited to this form. For example, in the terminal structure 1B shown in Figure 5, the lower end of the semi-conductive portion 92 of the stress cone 9 can be electrically connected to the metal cylinder 5 using wires 52a and 52b, and the semi-conductive portion 92 of the stress cone 9 and the lower flange portion 4 can be grounded via the metal cylinder 5 using wires (grounding wires) 51, 52a, and 52b.

[0083] That is, the cable 2 has at least a conductor 21, an insulation layer 22 covering the conductor 21, and an outer semiconductive layer 23 covering the insulation layer 22. The terminal structure 1B of the cable 2 of the present invention is a structure with a terminal portion 20 of the cable 2 formed by stripping the outer semiconductive layer 23, the insulation layer 22 and the conductor 21 in sequence towards the terminal 2a side of the cable 2. The terminal structure 1B includes: an insulating tube 3, which houses the terminal portion 20 of the cable 2 and is filled with an insulating fluid; a lower flange portion 4 made of metal, which has a through hole 40 for inserting the terminal portion 20 of the cable 2; and a metal cylinder 5, which is used to insert the through hole 40 of the lower flange portion 4. In the closed state, it can slide relative to the lower flange portion 4 in response to the extension and retraction of the cable 2; the sealing structure portion 6 seals the upper end portion 5a of the metal cylinder 5 and the stripped portion of the outer semiconductive layer 23 of the cable 2 corresponding to the upper end portion 5a of the metal cylinder 5; the conductive buffer layer 7 covers the stripped portion of the outer semiconductive layer 23 located on the side closer to the terminal 2a than the sealing structure portion 6; and the stress cone 9 is provided at the boundary between the insulation layer and the outer semiconductive layer of the cable, and is composed of an insulation portion 91 and a semiconductive portion 92; wherein, the semiconductive portion 92 of the stress cone 9 and the lower flange portion 4 are grounded by wires 51, 52a, 52b.

[0084] In the terminal structure 1B of this embodiment, wires 52a and 52b are wired from the semiconducting portion 92 of the stress cone 9, across the sealing structure portion 6 and the buffer layer 7, to a component such as a metal cylinder 5 that is grounded on the lower flange portion 4. In this way, even if the metal cylinder 5 slides relative to the lower flange portion 4 in response to the extension and retraction of the cable 2, the conduction between the semiconducting portion 92 of the stress cone 9 and the metal cylinder 5 can be maintained, so the grounding state of the semiconducting portion 92 of the stress cone 9 can be maintained, and the electric field in the terminal portion 20 of the cable 2 can be mitigated.

[0085] Here, the materials used for conductors 52a and 52b can include conductive metals, and more specifically, copper and aluminum. Furthermore, conductors 52a and 52b can be single wires, or, from an ease of operation perspective, braided wires.

[0086] In the terminal structure 1B shown in Figure 5, one end of the wire 52a is connected to the semiconductive portion 92 of the stress cone 9. Similarly, one end of the wire 52b is connected to a component such as a metal cylinder 5 that is grounded to the lower flange 4. Here, it is preferable that the connection points of the wires 52a and 52b with the semiconductive portion 92 and the component grounded to the lower flange 4 are fixed separately. This ensures more reliable electrical continuity between the wires 52a and 52b and the semiconductive portion 92 and the component grounded to the lower flange 4. Besides welding, methods such as fastening using binding members can be used to fix the wires 52a and 52b to the semiconductive portion 92 and the component grounded to the lower flange 4. Furthermore, binding members can include metal wires, metal straps, metal strips, and semiconductive strips.

[0087] Furthermore, the ends of wires 52a and 52b that are not connected to the semiconductive portion 92 and the metal cylinder 5 are preferably made detachable by means of crimp terminals or the like. In this way, when the terminal structure 1B is assembled onto the terminal portion 20 of the cable 2, it is easy to form a wire that is grounded on the lower flange portion 4 from the stress cone 9.

[0088] Wires 52a and 52b extend from the semi-conductive portion 92 of the stress cone 9, across the sealing structure portion 6 and the buffer layer 7, and are wired to a component such as a metal cylinder 5 that is grounded to the lower flange portion 4. Here, to prevent wire breakage due to sliding movement of the metal cylinder 5, wires 52a and 52b are preferably configured so as not to come into contact with either or both of the sealing structure portion 6 and the buffer layer 7.

[0089] Furthermore, the combined length of conductors 52a and 52b is preferably longer than the straight-line distance between the connection points of conductors 52a and 52b when they extend due to energization of cable 2. This allows the lengths of conductors 52a and 52b to be adjusted to a length that does not impede the sliding movement of the metal cylinder 5 relative to the lower flange 4.

[0090] Furthermore, in the terminal structure 1B of cable 2 in Figure 5, it is shown that the lower end of the semi-conductive portion 92 of the stress cone 9 is connected to the metal cylinder 5 by two wires 52a and 52b, but it is not limited to this configuration. For example, the lower end of the semi-conductive portion 92 of the stress cone 9 can also be connected to a component such as the metal cylinder 5 that is grounded on the lower flange portion 4 by a single wire (not shown).

[0091] Furthermore, in the cable 2 terminal structure 1B of Figure 5, a configuration is shown where the semiconducting portion 92 of the stress cone 9 is grounded to the lower flange portion 4 via the metal cylinder 5 and wires 51, 52a, and 52b, without the metal layer 8. However, this configuration is not limited to this configuration. For example, a metal layer 8 covering the outer surface of the buffer layer 7 and at least the upper end 5a of the metal cylinder 5 may be provided, and the semiconducting portion 92 of the stress cone 9 may be grounded to the lower flange portion 4 via the metal layer 8 and wires 51, 52a, and 52b. That is, the wires 52a and 52b may also be used for wiring between the semiconducting portion 92 of the stress cone 9 and the metal layer 8, spanning the sealing structure portion 6 and the buffer layer 7. In this way, the semiconducting portion 92 of the stress cone 9 and the buffer layer 7 can be electrically connected to the lower flange portion 4 for grounding via the metal layer 8 and the metal cylinder 5, thereby improving the voltage withstand characteristics of the cable 2 terminal portion 20.

[0092] In this case, when the semiconductive portion 92 of the stress cone 9 is grounded to the lower flange portion 4 via the metal layer 8 and wires 51, 52a, and 52b, wire 52b is preferably fixed to the metal layer 8 by soldering. In this case, the connection point of wires 52a and 52b is preferably located near the lower end of the semiconductive portion 92 of the stress cone 9. Furthermore, from the viewpoint of forming the terminal structure in fewer steps, wire 52b is preferably fixed together with the metal layer 8 by the solder fixing portion 82 of the metal layer 8.

[0093] The above describes the embodiments of the present invention. However, the present invention is not limited to the above embodiments, but includes all the forms covered by the concept of the present invention and the scope of the claims, and various changes can be made within the scope of the present invention.

[0094] 1,1A: Cable termination structure 2: Cable 2a: Cable termination 20: Cable termination 21: Conductor 22: Insulation layer 23: External semiconductive layer 24: Shielding layer 25: Cable sheath 26: Anti-corrosion layer 3: Insulating tube 31: Frame 31a: Opening on the upper side of the frame 31b: Opening on the lower side of the frame 32: Jacket 33: Conductor lead-out rod 34: Upper conductor fixing part 4: Lower flange portion 40: Through hole in the lower flange 41:Tubular part 42: Flange portion 43:Support the yinzi 44: Metal casing 5: Metal cylinder 5a: Upper end of the metal cylinder 51: Wire (Grounding Wire) 6: Sealing structure section 7: Buffer layer 71: Semiconducting band layer 7a: Upper end of the buffer layer 7b: Gap at the upper end of the semiconducting band 8: Metal layer 81: Metal strip layer 81a: Starting end of metal strip winding 81b: End of winding of metal strip 82: Solder adhesion part 83: Metal wire 9: Stress cone 9a: Lower end of the stress cone 9b: Lower end of the semiconducting part 91: Insulation part of the stress cone 92: Semiconducting part of the stress cone S: Internal space of the insulating tube X: Cable extension direction L: Spacing of solder fixation area

[0095] Domestic storage information (please note in order of storage institution, date, and number) none Overseas storage information (please note in the order of storage country, institution, date, and number) none

Claims

1. A cable termination structure, the cable having at least a conductor, an insulating layer covering the conductor, and an outer semiconductive layer covering the insulating layer, the cable termination structure being a structure having a cable termination portion formed by stripping the outer semiconductive layer, the insulating layer, and the conductor in sequence toward the termination side of the cable, characterized in that it comprises: an insulating tube housing the termination portion of the cable and filled with an insulating fluid; a lower flange portion made of metal having a through hole for inserting the termination portion of the cable; a metal cylinder that, when the through hole of the lower flange portion is closed, can slide relative to the lower flange portion in response to the extension and retraction of the cable; a sealing structure portion sealing the upper end of the metal cylinder and the stripped portion of the outer semiconductive layer of the cable corresponding to the upper end of the metal cylinder; a conductive buffer layer covering the stripped portion of the outer semiconductive layer located further toward the termination side than the sealing structure portion; and, A metal layer covers the outer surface of the aforementioned buffer layer and at least the upper end of the aforementioned metal cylinder; wherein, The aforementioned metal cylinder and the aforementioned lower flange are grounded via a wire.

2. The cable termination structure as described in claim 1, wherein, The aforementioned buffer layer is a single layer.

3. The cable termination structure as described in claim 1, wherein, The aforementioned buffer layer is formed by winding a semiconductive strip around the peeled portion of the aforementioned outer semiconductive layer.

4. The cable termination structure as described in claim 3, wherein, The gap at the upper end of the aforementioned buffer layer, at the upper end of the aforementioned semiconductive strip, is approximately parallel to the extension direction of the aforementioned cable.

5. The cable termination structure as described in claim 1, wherein, The aforementioned metal layer is formed by winding a metal strip at least from the outer surface of the aforementioned buffer layer to the outer surface that extends to a point lower than the upper end of the aforementioned metal cylinder.

6. The cable termination structure as described in claim 5, wherein, The aforementioned metal layer is formed by winding the aforementioned metal strip from a position lower than the upper end of the aforementioned metal layer until it reaches the aforementioned upper end position, and then winding it towards the upper end of the aforementioned metal cylinder to cover the starting end of the winding of the aforementioned metal strip.

7. The cable termination structure as described in claim 5, wherein, The aforementioned metal layer is formed by winding a metal strip made of fine metal wires.

8. The cable termination structure as described in claim 5, wherein, The aforementioned metal layer has an overlapping winding structure in which the aforementioned metal strips are wound in a state where they partially overlap each other, and the winding end of the aforementioned metal strips is located on the outer surface of the aforementioned metal cylinder.

9. The cable termination structure as described in claim 5, wherein, The aforementioned metal layer has a solder-fixing portion that fixes at least one of the winding start end and winding end end of the aforementioned metal strip.

10. The cable termination structure as described in claim 9, wherein, The aforementioned solder-attached portions exist at multiple locations on the aforementioned metal layer at intervals along the extension direction of the aforementioned cable.

11. The cable termination structure as described in claim 1, wherein, The aforementioned metal layer forms the outermost layer of the aforementioned terminal portion of the aforementioned cable.

12. A cable termination structure, the cable having at least a conductor, an insulating layer covering the conductor, and an outer semiconductive layer covering the insulating layer, the cable termination structure being a structure having a cable termination portion formed by stripping the outer semiconductive layer, the insulating layer, and the conductor in sequence toward the termination side of the cable, characterized in that it comprises: an insulating tube housing the termination portion of the cable and filled with an insulating fluid; a lower flange portion made of metal having a through hole for inserting the termination portion of the cable; a metal cylinder that, when the through hole of the lower flange portion is closed, can slide relative to the lower flange portion in response to the extension and retraction of the cable; a sealing structure portion sealing the upper end of the metal cylinder and the stripped portion of the outer semiconductive layer of the cable corresponding to the upper end of the metal cylinder; a conductive buffer layer covering the stripped portion of the outer semiconductive layer located further toward the termination side than the sealing structure portion; and, A stress cone, disposed at the boundary between the insulation layer and the outer semiconductive layer of the aforementioned cable, is composed of an insulating portion and a semiconductive portion; wherein, The semi-conductive part of the aforementioned stress cone and the aforementioned lower flange are grounded using a wire.

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