Insulating tube units, cable terminations and equipment bushings

Abstract

To provide a porcelain tube unit capable of reducing its weight while securing insulation performance, a cable end edge connection part, and a bushing for equipment.SOLUTION: A porcelain tube unit includes: a porcelain tube where a shade section is formed on an outer peripheral surface; an insulation unit disposed in the porcelain tube; and a gelatinous or solid insulation medium disposed in the porcelain tube to encircle the insulation unit. An interface between the insulation medium and the internal space is formed by an internal space on an end side of the insulation medium in the porcelain tube, an inner peripheral edge of the interface contacts a central conductor drawn from the insulation unit, and the insulation medium is formed so that an interface height of the interface becomes lower as it goes outward in a radial direction from the central conductor.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a hollow insulator unit, a cable termination connection part, and a bushing for equipment. [Background technology]

[0002] Conventionally, air terminations that perform air insulation using an insulating tube have been known as cable terminations provided at the ends of power cables (see, for example, Patent Documents 1 to 3). In air terminations, an insulating medium such as insulating oil (e.g., silicone oil) is generally enclosed within the insulating tube. In particular, in the air terminations disclosed in Patent Documents 1 to 3, etc., a solid insulator that has hardened into a gel state (also called a gel state) is used as the insulating medium. In this specification, an insulating unit disposed within an insulating tube and containing an insulating medium is referred to as an "insulating tube unit."

[0003] When a solid insulator is used as the insulating medium, there is little risk of the insulating medium leaking out, and therefore, from a structural standpoint, it is suitable for assembling the hollow insulator unit in a factory and transporting it to the construction site. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5804948 [Patent Document 2] JP 2010-016986 A [Patent Document 3] Patent No. 5804684 [Patent Document 4] Patent No. 5606252 [Non-patent literature]

[0005] [Non-Patent Document 1] Showa Electric Wire Review, "Development and Practical Application of 66 / 77kV Direct Molded Through Bushings", Vol. 56, No. 1 (2006) pp. 15-19 Summary of the Invention [Problem to be solved by the invention]

[0006] However, hollow insulator units using solid insulators are disadvantageous in terms of weight when transported. Also, in order to ensure a certain level of insulation performance, the solid insulator needs to be formed at a certain height, and simply lowering the position of the interface between the solid insulator and the space inside the hollow insulator (the height of the solid insulator) may result in a decrease in insulation performance.

[0007] An object of the present invention is to provide a hollow insulator unit, a cable termination connection part, and a bushing for equipment that can be made lighter while ensuring insulation performance. [Means for solving the problem]

[0008] The hollow insulator unit according to the present invention comprises: an insulator having a cap portion formed on an outer circumferential surface; an insulating unit disposed in the hollow insulator; a gel or solid insulating medium disposed in the hollow insulator so as to surround the insulating unit; an internal space on a tip side of the insulating medium in the hollow insulator forms an interface between the insulating medium and the internal space, an inner peripheral edge of the interface contacts a central conductor drawn out from the insulating unit; The insulating medium is formed such that the interface height decreases from the central conductor toward the outside in the radial direction.

[0009] The cable termination according to the present invention comprises: A cable termination including the above-mentioned insulator unit, The insulating unit includes at least an inner conductor and an insulating sleeve body that is integrally provided on an outer periphery of the inner conductor, a cable terminal portion of a cable to be attached to the hollow insulator unit is connected to a rear end side of the insulating unit, The rear end side of the inner conductor and the cable conductor of the cable are electrically connected.

[0010] The bushing for an equipment according to the present invention comprises: A through bushing for equipment comprising the above hollow insulator unit, The insulating unit includes at least an inner conductor and an insulating sleeve body that is integrally provided on an outer periphery of the inner conductor, a head portion having a shape tapering toward the rear end side and disposed within the device is disposed on the rear end side of the insulating unit, The internal conductor has a structure that penetrates and protrudes from the head portion. Effect of the Invention

[0011] According to the present invention, it is possible to reduce the weight of an insulating tube unit while ensuring the insulation performance of the insulating tube unit. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a cross-sectional view showing a cable connection portion according to an embodiment of the present invention. [Diagram 2] FIG. 2 is an enlarged schematic diagram showing the vicinity of the tip face of the insulating medium. [Diagram 3] FIG. 3 is a diagram showing an example of the relationship between the interface angle and the electric field intensity at the inner edge of the interface (triple junction). [Figure 4] FIG. 4 is a diagram showing an example of the relationship between the height of the insulating medium and the electric field intensity at the inner periphery of the interface. [Diagram 5] FIG. 5 is a diagram showing an example of the electric field intensity at the midpoint of the interface and the height of the insulating medium. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0014] FIG. 1 is a cross-sectional view showing a cable connecting end A to which a hollow insulator unit 1 according to an embodiment is applied.

[0015] 1, the cable termination connection part A includes an insulator unit 1 including an insulator 10, an insulating unit 20, an electric field mitigation part 30, a fixing metal fitting 41, a terminal mounting metal fitting 42, an insulating medium 43, a conductor pull-out rod 44, etc., and a cable terminal part 50. In the following description, the side from which the conductor pull-out rod 44 is pulled out is referred to as the "front end side," and the side to which the cable terminal part 50 is attached is referred to as the "rear end side."

[0016] The hollow insulator 10 has a hollow insulator body 11 having a cap portion 11a (see FIG. 2A) formed on the outer circumferential surface, an upper metal fitting 12 that seals the tip end side of the hollow insulator body 11, and a lower metal fitting 13 that is integrally provided on the rear end side of the hollow insulator body 11. The tip end side of the upper metal fitting 12 is covered with an upper protective metal fitting 14.

[0017] The hollow insulator body 11 may be, for example, a polymer hollow insulator (also called a composite hollow insulator) in which a polymer covering made of a polymer insulating material such as silicone rubber is integrally formed on the outside of a cylindrical body made of fiber reinforced plastics (FRP) as shown in Fig. 1, or may be a porcelain hollow insulator. The length of the hollow insulator body 11, i.e., the effective insulation length, is set so as to satisfy the lightning impulse withstand voltage required for the cable termination connection part A.

[0018] The insulating unit 20 has an inner conductor 21 extending in the axial direction, an insulating sleeve body 22 disposed on the outer circumferential surface of the inner conductor 21, and a shielding portion 23 formed on the outer circumferential surface of the insulating sleeve body 22, and functions as a reinforcing insulating portion of the cable termination connection portion A. The inner conductor 21 and the insulating sleeve body 22 are integrally formed by molding. The shielding portion 23 is formed, for example, by applying a conductive paint to the outer circumferential surface of the insulating sleeve body 22.

[0019] The inner conductor 21 is made of a conductive material suitable for electrical conduction, such as copper, aluminum, a copper alloy, or an aluminum alloy. The inner circumferential surface on the rear end side of the inner conductor 21 is exposed from the insulating sleeve body 22, and is provided with a conductor insertion portion 21a for electrically connecting the cable conductor 511. The end on the front end side of the inner conductor 21 passes through the insulating sleeve body 22 and is connected to the conductor lead-out rod 44.

[0020] The insulating sleeve body 22 is formed of a hard plastic resin material (e.g., epoxy resin or FRP) with high mechanical strength. A cone-shaped terminal insertion portion 22a that receives the cable terminal portion 50 is provided on the rear end side of the insulating sleeve body 22. The terminal insertion portion 22a communicates with the conductor insertion portion 21a of the inner conductor 21. The conductor insertion portion 21a and the terminal insertion portion 22a form the cable receiving portion 24 to which the cable terminal portion 50 is attached.

[0021] The shielding portion 23 is formed, for example, on the outer circumferential surface of the insulating sleeve body 22, from the large diameter portion at the rear end side to the middle position of the small diameter portion at the front end side of the insulating unit 20. By providing the shielding portion 23, the electric field is not concentrated between the internal conductor 21 and the shielding portion 23, and the internal electric field of the insulating sleeve body 22 is made uniform, thereby stabilizing the electrical characteristics.

[0022] The electric field mitigation section 30 is formed of a cylindrical elastic body having an insulating section 31 on the tip side and a conductive section 32 on the rear end side. The insulating section 31 is concentrically connected to the conductive section 32 on the rear end side, and is formed into a cylindrical shape from an insulating rubber material such as ethylene propylene rubber (EP rubber).

[0023] The conductive part 32 has a shape curved in a bell-mouth shape at the tip end, gradually expanding from the inner periphery near the tip end toward the tip side. The conductive part 32 is formed in a cylindrical shape from a semiconductive rubber material such as semiconductive EP rubber, and is connected to the insulating part 31 at the tip side of the inner periphery and at the part from the tip side to the rear end of the outer periphery. The inner periphery of the conductive part 32 is exposed as the inner periphery of the electric field mitigation part 30 except for the tip side part integrated with the insulating part 31, and is connected to the inner periphery of the insulating part 31. The insulating part 31 and the conductive part 32 are integrally formed by molding.

[0024] 1, the electric field mitigation section 30 has an outer shape that is cylindrical with the rear end side of the conductive section 32 exposed, but the outer shape is not particularly limited. The electric field mitigation section 30 is arranged so that it overlaps with the outer peripheral surface of the small diameter portion on the tip side of the insulating unit 20 so that the inner peripheral surface of the conductive section 32 and the shielding section 23 are conductive, and the tip of the shielding section 23 does not protrude from the inner peripheral surface of the conductive section 32 to the tip side. The electric field mitigation section 30 suppresses electric field concentration at the tip of the shielding section 23 and relieves electrical stress on the insulating sleeve body 22.

[0025] The fixing metal fitting 41 is a flange-shaped member having an opening for passing the insulating unit 20 therethrough. The fixing metal fitting 41 is disposed on the rear end side of the hollow insulator body 11, and is fastened to the lower metal fitting 13 of the hollow insulator 10, for example, by bolting. In addition, a support insulator 45 is disposed on the rear end side of the fixing metal fitting 41, and is fastened to the lower metal fitting 13 by bolting, for example.

[0026] The terminal mounting bracket 42 is a cylindrical member with a bottom that is arranged on the outer circumferential surface of the rear end (large diameter portion) of the insulation unit 20. An opening 42b for inserting the cable terminal portion 50 is provided in a bottom portion 42a of the terminal mounting bracket 42. The terminal mounting bracket 42 is arranged on the rear end side of the fixing bracket 41, and is fastened to the fixing bracket 41 and the insulation unit 20 by, for example, bolting.

[0027] The inner diameters of the fixing bracket 41 and the terminal mounting bracket 42 are approximately the same as the outer diameter of the rear end of the insulation unit 20. A seal member 46 such as an O-ring is disposed between the fixing bracket 41 and the insulation unit 20. By interposing the seal member 46 between the fixing bracket 41 and the insulation unit 20, the inside of the hollow insulator body 11 can be kept airtight or liquidtight to prevent the insulating medium 43 from leaking, and bending stress generated in the hollow insulator body 11 can be alleviated. It is preferable that a plurality of seal members 46 are provided at predetermined intervals in the axial direction.

[0028] The insulating medium 43 is filled in the space inside the hollow insulator 10 (hollow insulator body 11). Specifically, it is filled in at least the space between the hollow insulator 10 (hollow insulator body 11) and the insulating unit 20, and functions as a part of the main insulating part of the cable termination connection part A. The insulating medium 43 is a gel-like or solid insulating material arranged in the hollow insulator body 11 so as to surround the insulating unit 20. The insulating medium 43 is formed, for example, by injecting an insulating material having fluidity into the inside of the hollow insulator 10 (inside the hollow insulator body 11) and then hardening it. The insulating medium 43 is, for example, silicone gel or silicone rubber. "So as to surround the insulating unit 20" means that the insulating medium 43 is filled in the hollow insulator 10 to at least the height of the insulating unit 20 or more.

[0029] The insulating medium 43 is filled in the hollow insulator 10 at a predetermined height h. In this embodiment, the insulating medium 43 is filled in the space between the hollow insulator 10 (hollow insulator body 11) and the insulating unit 20, as well as in a part of the space between the hollow insulator 10 (hollow insulator body 11) and the conductor drawing rod 44 above the hollow insulator 10. By filling the insulating medium 43 in the space between the hollow insulator 10 (hollow insulator body 11) and the conductor drawing rod 44, an internal space 45 is formed in the hollow insulator 10 (hollow insulator body 11) on the tip side of the insulating medium 43. In this embodiment, an interface 431 (tip surface of the insulating medium 43) between the insulating medium 43 and the internal space 45 has a predetermined shape such as a tapered shape, rather than a horizontal interface. In this embodiment, the internal space 45 is formed by an air layer.

[0030] Hereinafter, the height of interface 431 based on the end portion on the rear end side of hollow insulator body 11 (the end portion on the front end side of lower metal fitting 13) is referred to as the "interface height". When the interface between insulating medium 43 and internal space 45 is a horizontal interface, the interface height of insulating medium 43 is constant, and therefore the interface height and height h of insulating medium 43 are the same. On the other hand, when the interface between insulating medium 43 and internal space 45 is not a horizontal interface as in this embodiment, the interface height differs depending on the position on interface 431. In this embodiment, for convenience, the interface height of interface inner periphery P1 (see FIG. 2) of insulating medium 43 is treated as height h of insulating medium 43. The shape of interface 431 of insulating medium 43 will be described later.

[0031] The conductor lead rod 44 is an example of a central conductor in which a uniform electric field is generated, and the rear end of the conductor lead rod 44 is connected to the internal conductor 21 of the insulating unit 20, and the front end passes through the upper metal fitting 12 and the upper protective metal fitting 14 of the hollow insulator 10 and is led out to the outside. The conductor lead rod 44 is connected to the internal conductor 21 of the insulating unit 20, for example, via an appropriate conductor connecting member.

[0032] The portion of the conductor pull-out rod 44 disposed inside the hollow insulator body 11 may be made of a flexible conductor such as a cable. In this case, the front end of the cable is connected to the rear end of the conductor rod that penetrates the upper metal fitting 12 and the upper protective metal fitting 14 and is drawn out to the outside, and the conductor pull-out rod 44 is formed by a plurality of members including the conductor rod and the cable disposed inside the hollow insulator body 11. By forming the portion of the conductor pull-out rod 44 disposed inside the hollow insulator 10 with a cable, the flexible cable can absorb the bending stress generated in the hollow insulator body 11, and excessive stress can be prevented from being generated in the insulating unit 20 inside. Furthermore, by using a cable covered with an insulating coating, the electric field generated on the surface of the conductor pull-out rod 44 can be suppressed.

[0033] The internal conductor 21 of the insulating unit 20 may be formed long, and may be configured to be drawn out from the upper metal fitting 12. In this case, the internal conductor 21 and the conductor lead-out rod 44 are formed from the same material, eliminating the need for the conductor lead-out rod 44, which is a separate material from the internal conductor 21, and the internal conductor also functions as a conductor lead-out rod.

[0034] That is, the "center conductor" in the present invention is not limited to the conductor pull-out rod 44, but may be a cable conductor in the case where the inner conductor 21 and the conductor pull-out rod 44 constituting the insulating unit 20 are configured as a cable. When the above-mentioned inner conductor 21 and the conductor pull-out rod 44 are formed of the same material, the same material is the "center conductor".

[0035] The cable terminal portion 50 is configured by attaching connecting materials such as a conductor connecting terminal 52, a stress cone 53, and a compression device 54 to the tip portion of a power cable 51.

[0036] The power cable 51 is, for example, a 275 kV class extra-high voltage power cable insulated with rubber or plastic. The power cable 51 includes, in order from the center, a cable conductor 511, a cable insulator 512, a cable outer semiconductive layer 513, a cable shielding layer 514, and a cable sheath 515. At the cable terminal 50, each layer is exposed by step-stripping a predetermined length from the tip of the power cable 51.

[0037] A conductor connection terminal 52 is connected to the tip of the cable conductor 511 by compression. The conductor connection terminal 52 is made of a conductive material suitable for current flow, such as copper, aluminum, a copper alloy, or an aluminum alloy. A stress cone 53 is attached to the outer circumferential surface ranging from the cable insulator 512 to the tip of the cable outer semiconductive layer 513.

[0038] The stress cone 53 is formed in a spindle shape, and has an insulating portion (reference number omitted) at the tip end side and a conductive portion (reference number omitted) at the rear end side, similar to the electric field mitigation portion 30. The insulating portion is formed in a cylindrical shape from an insulating rubber material such as EP rubber, and the conductive portion is formed in a cylindrical shape from a semiconductive rubber material such as semiconductive EP rubber. The insulating portion and the conductive portion are integrally formed by molding.

[0039] The rear end (semiconductive portion) of the stress cone 53 is connected to the cable external semiconductive layer 513 of the power cable 51. As long as the rear end of the stress cone 53 has a predetermined performance as a cable termination connection portion, it may be directly connected to the cable external semiconductive layer 513, or may be connected to the end of the cable external semiconductive layer 513 via an end of an external semiconductive layer reproduced by molding or conductive paint. The tip portion (insulating portion) of the stress cone 53 has a shape corresponding to the cable receiving portion 24 of the insulating unit 20. A compression device 54 and a cable protection metal fitting 55 are attached to the rear end side of the stress cone 53.

[0040] The compression device 54 has, for example, a pressing fitting (symbol omitted) that abuts against the stress cone 53, a coil spring (symbol omitted) that urges the pressing fitting toward the stress cone 53, and a pressing fitting flange (symbol omitted) that supports the pressing fitting and the coil spring.

[0041] After the tip of the power cable 51 is stripped in stages, the cable protection fitting 55, the compression device 54, and the stress cone 53 are inserted into the power cable 51, and the conductor connection terminal 52 is attached to the cable conductor 511. Then, the tip of the cable terminal portion 50 is inserted into the cable receiving portion 24 of the insulation unit 20, and while compressing the coil spring of the compression device 54, the pressing fitting flange is bolted to the bottom portion 42a of the terminal mounting fitting 42, and the cable protection fitting 55 is bolted to the pressing fitting flange, thereby mounting the cable terminal portion 50 to the cable receiving portion 24.

[0042] The tip of the stress cone 53 is pressed against the inner surface of the insulating sleeve body 22, and the conductor connection terminal 52 is electrically connected to the conductor insertion portion 21a of the inner conductor 21. In addition, a corrosion-resistant layer (reference number omitted) for waterproofing is disposed on the rear end of the cable protection metal fitting 55. In this manner, the cable termination connection part A can be assembled with a relatively simple operation by plug-in connection.

[0043] In a conventional hollow insulator unit (see, for example, Patent Document 1), the interface between the insulating medium sealed in the hollow insulator and the internal space of the hollow insulator is a horizontal interface perpendicular to the axial direction. In contrast, in the present embodiment, interface 431 of insulating medium 43 is formed at an angle with respect to conductor lead rod 44 arranged along the axial direction.

[0044] FIG. 2 is an enlarged schematic diagram showing the vicinity of the tip surface of the insulating medium 43 (interface 431 between the insulating medium 43 and the internal space 45).

[0045] 2, at an interface 431 between the insulating medium 43 and the internal space 45, the interface height of an interface inner periphery P1 in contact with the conductor pull-out rod 44 is higher than the interface height of an interface outer periphery P2 in contact with the hollow insulator body 11. In other words, the insulating medium 43 is formed so that the interface height decreases toward the outside in the radial direction. The interface inner periphery P1 is called a "triple junction" because the insulating medium 43, the conductor pull-out rod 44, and the internal space 45 are in contact with each other.

[0046] For example, after injecting a fluid insulating material into the inside of the hollow insulator 10 (inside the hollow insulator body 11), a die is abutted against the tip end surface of the insulating material and the insulating material is hardened while applying pressure, whereby the tip end surface of the insulating medium 43, i.e., the interface 431 between the insulating medium 43 and the internal space 45, can be formed into a predetermined shape corresponding to the abutment surface of the die.

[0047] By forming insulating medium 43 so that the interface height decreases toward the outside in the radial direction, the electric field strength (particularly the electric field strength of the triple junction) at interface 431 between insulating medium 43 and internal space 45 is reduced compared to when interface 431 is a horizontal interface (see the dashed line in FIG. 2). Therefore, the amount of insulating medium 43 filled to achieve a desired insulation strength can be reduced compared to when the interface is a horizontal interface, and the weight of hollow insulator unit 1 can be reduced.

[0048] Preferably, the interface height of the insulating medium 43 monotonically decreases from the conductor pull-out rod 44 toward the outside in the radial direction. Typically, the term "monotonically decreasing interface height" means that the shape of the interface 431 is a tapered shape that linearly expands toward the rear end side, as shown in FIG. 2, formed on the surface of a rotating body rotated around the conductor pull-out rod 44 according to a function that linearly decreases from the interface inner periphery P1 toward the outside in the radial direction from the conductor pull-out rod 44. The shape of the interface 431 may be a shape that curves toward the front end side or curves toward the rear end side, formed on the surface of a rotating body rotated around the conductor pull-out rod 44 according to an upwardly convex or downwardly convex function that curvedly decreases from the interface inner periphery P1 toward the outside in the radial direction from the conductor pull-out rod 44. As shown in FIG. 2, the angle θ between the conductor pull-out rod 44 and the interface 431 when the interface 431 has a tapered shape is referred to as the "interface angle θ". The angle between the conductor lead rod 44 and the interface 431 has a front end side (internal space 45 side) and a rear end side (insulating medium 43 side), and the interface angle θ indicates the angle on the insulating medium 43 side (rear end side).

[0049] The effectiveness of forming the insulating medium 43 so that the interface height decreases toward the outside in the radial direction will be described below.

[0050] Fig. 3 is a diagram showing an example of the relationship between the interface angle θ and the electric field strength at the interface inner periphery P1 (triple junction). Fig. 3 shows the case where the interface 431 is formed in a tapered shape. Fig. 3 also shows the electric field strength with respect to the interface angle θ as a percentage, with the electric field strength being 100% for a horizontal interface with an interface angle θ of 90°.

[0051] As shown in Fig. 3, by making the interface angle θ smaller than 90°, it is possible to reduce the electric field strength at the interface inner edge P1 where the electric field is most concentrated. Specifically, when the interface angle θ is set to 10 to 60°, the electric field strength can be reduced to 70% or less, and in particular, when the interface angle θ is set to 45°, the effect of reducing the electric field strength is maximized. It has been confirmed that the tendency shown in Fig. 3 does not depend on the height h of the insulating medium 43 (interface height of the interface inner edge P1) (see Fig. 4, for example).

[0052] Fig. 4 is a diagram showing an example of the relationship between the height h (see Fig. 1) of insulating medium 43 and the electric field strength at the interface inner edge P1. In Fig. 4, a case where interface 431 is formed in a tapered shape with an interface angle of 45° is indicated by "●", and a case where the interface is a horizontal interface with an interface angle of 90° is indicated by "○". Also, in Fig. 4, the electric field strength relative to the height h of insulating medium 43 is shown as a percentage, with the electric field strength at interface inner edge P1 at the horizontal interface where the height h of insulating medium 43 is 75% of the effective insulation length (the length of hollow insulator body 11) being taken as 100%.

[0053] From Figure 4, it can be seen that when the interface angle of interface 431 is 45° (see "●"), the electric field strength at the inner edge P1 of the interface can be reduced by 30 to 40% compared to the case of a horizontal interface (see "○"), regardless of the height h of insulating medium 43.

[0054] Fig. 5 is a diagram showing an example of the height h (see Fig. 1) of insulating medium 43 and the electric field intensity at interface midpoint P3 (see Fig. 2). Fig. 5 shows a case where interface 431 is formed in a tapered shape with an interface angle of 45°. Fig. 5 also shows the electric field intensity relative to height h of insulating medium 43 as a percentage, with the electric field intensity at interface midpoint P3 being 100% when height h of insulating medium 43 is 50% of the effective insulation length.

[0055] As shown in Fig. 5, increasing the height h of the insulating medium 43 enhances the effect of reducing the electric field strength. On the other hand, increasing the height h of the insulating medium 43 means that the amount of the insulating medium 43 filled in increases, leading to an increase in the weight of the hollow insulator unit 1. In order to reduce the weight of the hollow insulator unit 1 while ensuring the desired insulation strength, it is preferable that the height h of the insulating medium 43 is 60% or more and 80% or less of the effective insulation length. In addition, in all of Figs. 3, 4, and 5, the internal space 45 in the hollow insulator 10 (hollow insulator main body 11) is an air layer.

[0056] As described above, the hollow insulator 10 applied to the cable connection termination A according to the present embodiment has the following characteristics either alone or in appropriate combination.

[0057] That is, the hollow insulator unit 1 according to the embodiment includes a hollow insulator 10 having a cap portion 11a formed on its outer circumferential surface, an insulating unit 20 disposed in the hollow insulator 10, and a gel or solid insulating medium 43 disposed in the hollow insulator 10 so as to surround the insulating unit 20. An interface 431 between the insulating medium 43 and the internal space 45 is formed by an internal space 45 on the tip side of the insulating medium 43 in the hollow insulator 10, and an inner peripheral edge P1 of the interface 431 contacts a conductor pull rod 44 (center conductor) drawn out from the insulating unit 20. The insulating medium 43 is formed such that the interface height of the interface 431 decreases as it moves radially outward from the conductor pull rod 44 (center conductor).

[0058] According to the hollow insulator unit 1, the electric field strength at the interface 431 (particularly the electric field strength at the triple junction) is reduced compared to when the interface 431 is formed horizontally, so that the amount of insulating medium 43 required to realize a desired insulation strength can be reduced. Therefore, the hollow insulator unit 1 can be made lighter, which is advantageous for transportation to the construction site. In addition, the hollow insulator unit 1 can handle high voltages while suppressing an increase in weight.

[0059] Furthermore, according to the hollow insulator unit 1, the insulating medium 43 can be filled in advance at a factory and then transported to the construction site, eliminating the need for the work of filling the hollow insulator unit 1 with the insulating medium 43 at the construction site and shortening the construction period of the cable termination connection part A. In addition, since the insulating medium 43 is a gel or solid, leakage of the insulating medium 43 can be prevented even if the hollow insulator 10 is damaged, improving safety.

[0060] In addition, even if the insulating medium 43 leaks, the insulating medium 43 is in a gel or solid state, so that the soil is not contaminated as compared to the case where insulating oil is used, and therefore this is an environmentally friendly clean energy technology. In addition, when a polymer hollow shell is applied as the hollow shell unit 1 as in the embodiment, it is more earthquake-resistant and resistant to disasters than a porcelain hollow shell. Therefore, it is possible to contribute to the Sustainable Development Goals (SDGs), which are international goals aimed at a sustainable and better world by 2030 as stated in the "2030 Agenda for Sustainable Development" adopted at the United Nations Summit in September 2015, including Goal 7 "Ensure access to affordable, reliable, sustainable and modern energy for all," Goal 9 "Build resilient infrastructure, promote inclusive and sustainable industrialization and foster innovation," and Goal 11 "Make cities and human settlements inclusive, safe, resilient and sustainable."

[0061] In the hollow insulator unit 1, the interface height monotonically decreases from the conductor pull-out rod 44 (center conductor) toward the outside in the radial direction, thereby stabilizing the electric field distribution in the hollow insulator 10 and improving the insulation performance.

[0062] In the hollow insulator unit 1, interface 431 has a tapered shape that linearly expands in diameter toward the rear end side. This simplifies the shape of interface 431, stabilizing the quality of the interface shape and further improving the insulation performance.

[0063] In the insulator unit 1, the interface angle θ (the angle between the interface 431 and the conductor lead rod 44 (center conductor) on the insulating medium 43 side) is 10° or more and 80° or less. This makes it possible to effectively reduce the electric field intensity regardless of the height h of the insulating medium 43.

[0064] More preferably, the interface angle θ is 30° or more and 60° or less. This makes it possible to reduce the electric field intensity more effectively. Note that these interface angles θ are assumed to be in a tapered shape in which the interface 431 linearly expands in diameter toward the rear end side, but it is considered that the same effect can be obtained even if the shape of the interface 431 expands in a curved shape toward the front end side or recesses in a curved shape toward the rear end side based on the interface angle θ due to expansion / contraction of the insulating medium 43, etc.

[0065] In the hollow insulator unit 1, the hollow insulator 10 has at least a hollow insulator body 11 having a cap portion 11a formed on its outer circumferential surface, and the height h of the insulating medium 43 is 60% to 80% of the effective insulation length based on the end portion on the rear end side of the hollow insulator body 11. This makes it possible to reduce the weight of the hollow insulator unit 1 while ensuring the desired insulation performance.

[0066] In the hollow insulator unit 1, the insulating medium 43 is silicone gel or silicone rubber. This makes it possible to easily form the interface 431 of the insulating medium 43 into a predetermined shape using an existing insulating material.

[0067] Moreover, the cable termination connection part A in the embodiment is a cable termination connection part equipped with an insulator unit 1, and the insulating unit 20 has at least an inner conductor 21 and an insulating sleeve body 22 integrally formed on the outer periphery of the inner conductor 21, and a cable terminal part 50 of a power cable 51 attached to the insulator unit 1 is connected to the rear end side of the insulating unit 20, and the rear end side of the inner conductor 21 and a cable conductor 511 of the power cable 51 are electrically connected to each other.

[0068] The invention made by the inventor has been specifically described above based on an embodiment, but the present invention is not limited to the above embodiment and can be modified within the scope of the gist of the invention.

[0069] For example, in this embodiment, the case has been described where the cable terminal portion is plug-in connected using an inner cone type having a stress cone and a compression device, etc., but it may also be connected using an outer cone type in which the cable terminal portion and the insulation unit are connected with a rubber block.

[0070] In the embodiment, an example in which the hollow insulator unit according to the present invention is applied to a cable termination connection portion has been described, but the present invention is not limited to this, and may be applied to, for example, an air portion of an equipment bushing (also called an "equipment penetration bushing"). The equipment side of the equipment bushing has a known shape compatible with oil insulation and / or gas insulation, and can be used for transformers or GIS (gas insulated switchgear).

[0071] When applied to an equipment bushing, the rear end side of the insulating sleeve body of the insulating unit arranged in the insulator body 11 has a head portion that can withstand oil insulation and / or gas insulation in the equipment, rather than a cable receiving port structure like the receiving portion 24. The head portion is formed in a known shape including a portion that tapers in diameter from the front end side to the rear end side (in other words, tapers in diameter toward the inside of the equipment to which it is attached) (for example, see the equipment side shape of the through bushing in Figure 1 of Non-Patent Document 1 and the structure below the flange portion in Figure 1 of Patent Document 4).

[0072] That is, when the insulator unit of the present invention is applied to an equipment bushing, the rear end side of the inner conductor does not have a conductor insertion portion for connecting a cable conductor, and the rod-shaped inner conductor penetrates and protrudes from the head portion at the rear end side of the insulating sleeve body. The protruding rear end of the inner conductor may remain rod-shaped or may have a shield shape as a countermeasure against partial discharge. Also, a shielding metal fitting may be provided as appropriate to relieve the electric field of the head portion.

[0073] In the embodiment, the internal space 45 in the hollow insulator 10 (hollow insulator body 11) is described as an air space, but an insulating gas may be filled in as long as the effects of the present invention are achieved. Also, the pressure in the internal space 45 may be adjusted.

[0074] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0075] 1. Insulator unit 10 Insulator 11 Insulator body 20 Isolation Unit 21 Inner conductor 22 Insulating sleeve body 43 Insulating Media 431 Interface A Cable termination connection

Claims

1. an insulator having a cap portion formed on an outer circumferential surface; an insulating unit disposed in the hollow insulator; a gel or solid insulating medium disposed in the hollow insulator so as to surround the insulating unit; an internal space on a tip side of the insulating medium in the hollow insulator forms an interface between the insulating medium and the internal space, an inner peripheral edge of the interface contacts a central conductor drawn out from the insulating unit; The insulating medium is formed such that an interface height of the interface decreases from the central conductor toward the outside in the radial direction. Insulator unit.

2. the interface height monotonically decreases from the central conductor toward the outside in the radial direction; The hollow insulator unit according to claim 1 .

3. The interface has a tapered shape that linearly expands in diameter toward the rear end side. The hollow insulator unit according to claim 2 .

4. an angle between the interface and the central conductor on the insulating medium side is 10° or more and 80° or less; The hollow insulator unit according to claim 3 .

5. The hollow insulator has at least a hollow insulator body having the cap portion formed on an outer circumferential surface, The height of the insulating medium is 60% or more and 80% or less of the effective insulation length based on the end portion on the rear end side of the hollow insulator body. The hollow insulator unit according to claim 4.

6. The insulating medium is silicone gel or silicone rubber. The hollow insulator unit according to claim 1 .

7. A cable termination comprising the insulator unit according to claim 1, The insulating unit includes at least an inner conductor and an insulating sleeve body that is integrally provided on an outer periphery of the inner conductor, a cable terminal portion of a cable to be attached to the hollow insulator unit is connected to a rear end side of the insulating unit, a rear end side of the inner conductor and a cable conductor of the cable are electrically connected to each other; Cable termination connection.

8. A through bushing for equipment comprising the hollow insulator unit according to claim 1, The insulating unit includes at least an inner conductor and an insulating sleeve body that is integrally provided on an outer periphery of the inner conductor, a head portion having a shape tapering toward the rear end side and disposed within the device is disposed on the rear end side of the insulating unit, The internal conductor has a structure penetrating and protruding from the head portion. Equipment bushings.

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