Bushing

Abstract

To prevent a terminal of a bushing and a tank of an instrument transformer from being short-circuited by an arc without using a component for leveling.SOLUTION: One aspect of the present invention is a bushing for insulating a conductor for electrically connecting a gas-insulated switchgear and an instrument transformer for monitoring voltage and current in the gas-insulated switchgear. The bushing comprises a bushing body. The bushing comprises a terminal for connection to an instrument transformer. The bushing includes an electric field relaxation conductor that is provided between the bushing body and the terminal and relaxes an electric field with respect to the terminal. The electric field relaxation conductor has a disk shape. The side surface portion of the electric field relaxation conductor protrudes outward from the terminal.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a bushing. [Background technology]

[0002] The technology described in Patent Document 1 aims to eliminate internal stress caused by hardening and shrinkage of the resin in the insulating part of a cast bushing made of cast resin, and to provide a cast bushing of stable quality. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-256847 Summary of the Invention [Problem to be solved by the invention]

[0004] Because bushings are long in the axial direction of the conductor, metal parts are sometimes used to level them when connecting them to gas-insulated switchgear. The metal parts for leveling prevent short circuits caused by arcs between the bushing terminals and the tank of the instrument transformer. The metal parts for leveling can be omitted if the bushing is made shorter. However, if metal parts for leveling are not used, there is a possibility that the bushing terminals will short circuit with the tank of the instrument transformer due to arcs. [Means for solving the problem]

[0005] One aspect of the present invention is a bushing for insulating a conductor for electrically connecting the gas-insulated switchgear to an instrument transformer that monitors voltage and current in the gas-insulated switchgear. The bushing includes a bushing body. The bushing includes a terminal for connection to the instrument transformer. The bushing includes an electric field relaxation conductor that is provided between the bushing body and the terminal and relaxes an electric field relative to the terminal. The electric field relaxation conductor is disk-shaped. A side surface of the electric field relaxation conductor protrudes outward beyond the terminal. [Brief explanation of the drawings]

[0006] [Figure 1] 10 is a side view showing an example of a usage pattern of a U-phase bushing 100U, a W-phase bushing 100W, and a V-phase bushing 200. FIG. [Figure 2] 10 is a plan view showing an example of a usage pattern of a U-phase bushing 100U, a W-phase bushing 100W, and a V-phase bushing 200. FIG. [Figure 3] 1 is a front view showing an example of the configuration of a UW phase bushing 100. FIG. [Figure 4] 1 is a rear view showing an example of the configuration of a UW-phase bushing 100. FIG. [Figure 5] 1 is a side view showing an example of the configuration of a UW phase bushing 100. FIG. [Figure 6] 1 is a bottom view showing an example of the configuration of a UW-phase bushing 100. FIG. [Figure 7] 1 is a cross-sectional view showing an example of the configuration of a UW-phase bushing 100. FIG. [Figure 8] 10 is a perspective view showing an example of the configuration of a shield part 114. FIG. [Figure 9] 1 is a front view showing an example of the configuration of a V-phase bushing 200. FIG. [Figure 10] 1 is a side view showing an example of the configuration of a V-phase bushing 200. FIG. [Figure 11] 10 is a bottom view showing an example of the configuration of a V-phase bushing 200. FIG. [Figure 12] 2 is a cross-sectional view showing an example of the configuration of a V-phase bushing 200. FIG. [Figure 13]10 is a cross-sectional view showing another example of the configuration of the V-phase bushing 200. FIG. [Figure 14] 10 is a diagram showing the results of analyzing the potential distribution in the V-phase bushing 200. FIG. [Figure 15] 10 is a diagram showing the results of analyzing the electric field distribution in the V-phase bushing 200. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0007] The present invention will be described below using embodiments of the invention, but the following embodiments do not limit the scope of the invention according to the claims. Furthermore, not all of the combinations of features described in the embodiments are necessarily essential to the solution of the invention.

[0008] FIG. 1 is a side view showing an example of how the U-phase bushing 100U, W-phase bushing 100W, and V-phase bushing 200 are used. FIG. 2 is a plan view showing an example of how the U-phase bushing 100U, W-phase bushing 100W, and V-phase bushing 200 are used. The U-phase bushing 100U, W-phase bushing 100W, and V-phase bushing 200 are devices that insulate conductors for electrically connecting a gas-insulated switchgear G1 and an instrument transformer VC. The gas-insulated switchgear G1 uses sulfur hexafluoride gas as an insulating medium to provide high-voltage electrical switching functionality with a compact design. The instrument transformer VC is a current and voltage transformer used with a watt-hour meter, a reactive watt-hour meter, or a maximum demand watt-hour meter.

[0009] The potential transformer VC comprises a current transformer C1 and a voltage transformer VT. The current transformer C1 is a transformer that transforms a certain current value into a current value proportional to it. The voltage transformer VT is a transformer that transforms a certain voltage value into a voltage value proportional to it. The current transformer C1 and voltage transformer VT are housed in the tank T1 of the potential transformer VC and are immersed in insulating oil. The insulating oil is a medium that provides insulating and cooling functions. In other words, the potential transformer VC is an oil-filled potential transformer in which the main parts, such as the current transformer C1 and voltage transformer VT, are immersed in insulating oil. The insulating oil is filled up to around the upper bulkhead UB of the tank T1. Nitrogen gas is sealed above the insulating oil surface.

[0010] The U-phase bushing 100U, W-phase bushing 100W, and V-phase bushing 200 are provided through an opening O1 formed in an upper bulkhead UB of the instrument transformer VC. The U-phase bushing 100U and W-phase bushing 100W (hereinafter collectively referred to as UW-phase bushings 100) are connected to a current transformer C1. The V-phase bushing 200 is connected to a transformer VT.

[0011] 3 to 7 are diagrams showing an example of the configuration of the UW-phase bushing 100. FIG. 3 is a front view showing an example of the configuration of the UW-phase bushing 100. FIG. 4 is a rear view showing an example of the configuration of the UW-phase bushing 100. FIG. 5 is a side view showing an example of the configuration of the UW-phase bushing 100. FIG. 6 is a bottom view showing an example of the configuration of the UW-phase bushing 100. FIG. 7 is a cross-sectional view showing an example of the configuration of the UW-phase bushing 100.

[0012] The UW-phase bushing 100 includes a bushing body 110 , a gas-insulated switchgear terminal 120 , a current transformer terminal 130 , and an electric field relaxation conductor 140 .

[0013] The bushing body 110 includes a first central conductor 111 , a second central conductor 112 , an insulator 113 , a shielding portion 114 , and a plurality of mounting portions 115 .

[0014] The first central conductor 111 and the second central conductor 112 are conductors that pass through the center of the UW-phase bushing 100. The first central conductor 111 is an aluminum or copper conductor that allows current to flow from the gas-insulated switchgear G1 to the instrument transformer VC. The first central conductor 111 shown in FIG. 7 is formed in a cylindrical shape. The second central conductor 112 is an aluminum or copper conductor that allows current to flow from the instrument transformer VC to the gas-insulated switchgear G1. The second central conductor 112 shown in FIG. 7 is formed in a rod shape and inserted into the hollow portion of the first central conductor 111. The first central conductor 111 and the second central conductor 112 are insulated from each other by an inter-conductor insulator 116.

[0015] The insulator 113 is disposed around the first central conductor 111 and is a member that serves as the main insulator. The insulator 113 is formed of resin. That is, the UW phase bushing 100 is a resin bushing in which the insulator 113 is made of resin. For example, the insulator 113 is made of epoxy resin. That is, the UW phase bushing 100 is an epoxy resin bushing in which the insulator 113 is made of epoxy resin. The insulator 113 may be made of fiber-reinforced plastic or silicone. The insulator 113 is configured to have a substantially cylindrical outer shape and has a flange portion 113F. The flange portion 113F is disposed on the side surface of the insulator 113, closer to the current transformer C1 than the axial center portion. The radial size of the insulator 113 tapers from the flange portion 113F to both ends.

[0016] The shield portion 114 is a metal member that controls the electric field. For example, the shield portion 114 is made of aluminum or copper. The shield portion 114 is provided in the insulator 113 and spaced apart from the first central conductor 111. The shield portion 114 is provided closer to the current transformer C1 in the axial direction of the first central conductor 111 and the second central conductor 112.

[0017] 8 is a perspective view showing an example of the configuration of the shield part 114. The shield part 114 includes a first member 114A and two second members 114B.

[0018] The first member 114A is a mesh-like member formed in a cylindrical shape concentric with the first central conductor 111 and the second central conductor 112. The first member 114A is tin-plated. The mesh size of the first member 114A may vary depending on the type of resin that constitutes the insulator 113. For example, the mesh size of the first member 114A may vary depending on whether the insulator 113 is made of epoxy resin, fiber-reinforced plastic, or silicone. For example, the mesh size of the first member 114A may be set depending on the viscosity of the liquid before the resin that constitutes the insulator 113 hardens. For example, the mesh size of the first member 114A may be increased as the viscosity of the liquid before the resin that constitutes the insulator 113 hardens increases.

[0019] The second member 114B is a member formed in a spiral shape with the circumferential direction of the first member 114A as its axis. The second member 114B is provided on the outside of each open end of the first member 114A. The second member 114B is tin-plated.

[0020] Returning to the description of Figures 3 to 7, the multiple mounting portions 115 are metal members for mounting the UW-phase bushing 100 to the upper bulkhead UB of the instrument transformer VC. The multiple mounting portions 115 are provided on the flange portion 113F of the insulator 113. The multiple mounting portions 115 are provided spaced apart from one another at positions concentric with the first center conductor 111 and the second center conductor 112. The multiple mounting portions 115 are each connected to the shield portion 114 using a metal connecting member 117. The connecting members 117 connected to the multiple mounting portions 115 each have the same length.

[0021] The shield portion 114 is provided between the first and second central conductors 111, 112 and the mounting portion 115. The shield portion 114 is provided closer to the current transformer C1 in the axial direction of the first and second central conductors 111, 112, with the position of the mounting portion 115 as a reference.

[0022] The gas-insulated switchgear terminal 120 is a terminal for connecting the UW-phase bushing 100 to the gas-insulated switchgear G1. The gas-insulated switchgear terminal 120 includes a first terminal portion 121 and a second terminal portion 122. The first terminal portion 121 is connected to the first central conductor 111. The second terminal portion 122 is connected to the second central conductor 112.

[0023] The current transformer terminal 130 is a terminal for connecting the UW-phase bushing 100 to the current transformer C1. The UW-phase bushing 100 includes a first L-shaped terminal 131 and a second L-shaped terminal 132 as the current transformer terminals 130. The first L-shaped terminal 131 is connected to the first center conductor 111. The second L-shaped terminal 132 is connected to the second center conductor 112. The first L-shaped terminal 131 and the second L-shaped terminal 132 have a shape formed by bending a rectangular plate into an L shape. The first L-shaped terminal 131 and the second L-shaped terminal 132 are arranged so that the plate surfaces extending in the axial direction of the bushing body 110 face each other.

[0024] The electric field relaxation conductor 140 is a conductor that relaxes the electric field with respect to the current transformer terminal 130. The electric field relaxation conductor 140 is provided between the bushing body 110 and the current transformer terminal 130. The electric field relaxation conductor 140 is disk-shaped. The side surfaces of the electric field relaxation conductor 140 protrude outward beyond the bent portions of the first L-shaped terminal 131 and the second L-shaped terminal 132.

[0025] The axial length of the bushing body 110 is shorter than when the UW-phase bushing 100 does not include the electric field relaxation conductor 140 .

[0026] 9 to 13 are diagrams showing one example of the configuration of the V-phase bushing 200. FIG. 9 is a front view showing one example of the configuration of the V-phase bushing 200. FIG. 10 is a side view showing one example of the configuration of the V-phase bushing 200. FIG. 11 is a bottom view showing one example of the configuration of the V-phase bushing 200. FIG. 12 is a cross-sectional view showing one example of the configuration of the V-phase bushing 200. FIG. 13 is a cross-sectional view showing another example of the configuration of the V-phase bushing 200.

[0027] The V-phase bushing 200 includes a bushing body 210 , a gas-insulated switchgear terminal 220 , a transformer terminal 230 , and an electric field relaxation conductor 240 .

[0028] The bushing body 210 includes a center conductor 211 , an insulator 213 , a shield portion 214 and a plurality of mounting portions 215 .

[0029] The central conductor 211 is a conductor that passes through the center of the V-phase bushing 200. The central conductor 211 is a conductor made of aluminum or copper. The central conductor 211 shown in Figs. 12 and 13 is formed in a rod shape. The central conductor 211 has a small diameter portion 211B that is smaller in diameter than end portions 211A on both sides.

[0030] 12 is formed over the entire space between both end portions 211A. When formed over the entire space between both end portions 211A, small diameter portion 211B has a diameter that is 30% to 60% of the diameter of end portion 211A.

[0031] 13 is formed closer to the gas-insulated switchgear G1 than the central portion in the axial direction. When formed closer to the gas-insulated switchgear G1 than the central portion in the axial direction, the small diameter portion 211B has a diameter that is 30% to 40% of the diameter of the end portion 211A.

[0032] The insulator 213 is a member that is provided around the central conductor 211 and serves as a main insulator. The insulator 213 has a flange portion 213F. The insulator 213 has the same shape as the insulator 113 of the UW-phase bushing 100.

[0033] The shield portion 214 is a metal member that controls the electric field. The shield portion 214 has a first member 214A and a second member 214B. The shield portion 214 has a similar shape to the shield portion 114 of the UW-phase bushing 100. The first member 214A has a similar shape to the first member 114A of the shield portion 114 of the UW-phase bushing 100. The second member 214B has a similar shape to the second member 114B of the shield portion 114 of the UW-phase bushing 100.

[0034] The multiple mounting portions 215 are metal members for mounting the V-phase bushing 200 to the upper bulkhead UB of the instrument transformer VC. The mounting portions 215 have the same configuration as the mounting portions 115 of the UW-phase bushing 100. The multiple mounting portions 215 are each connected to the shield portion 214 using a metal connecting member 217. The connecting member 217 has the same configuration as the connecting member 117 of the UW-phase bushing 100.

[0035] The gas-insulated switchgear terminal 220 is a terminal for connecting the V-phase bushing 200 to the gas-insulated switchgear G1. The gas-insulated switchgear terminal 220 is connected to the central conductor 211.

[0036] The transformer terminal 230 is a terminal for connecting the V-phase bushing 200 to the transformer VT.

[0037] The electric field relaxation conductor 240 is a conductor that relaxes the electric field with respect to the transformer terminal 230. The electric field relaxation conductor 240 is provided between the bushing body 210 and the transformer terminal 230. The electric field relaxation conductor 240 is disk-shaped. The side surfaces of the electric field relaxation conductor 240 protrude outward beyond the transformer terminal 230.

[0038] The axial length of bushing body 210 is shorter than that in the case where V-phase bushing 200 does not include electric field relaxation conductor 240. The radial size of bushing body 210 is greater than that in the case where V-phase bushing 200 does not include electric field relaxation conductor 240.

[0039] FIG. 14 is a diagram showing the results of analyzing the potential distribution in the V-phase bushing 200. The potential is high near the center conductor 211, particularly near the end 211A of the center conductor 211. The potential decreases with increasing distance from the center conductor 211. The potential approaches zero on the outer circumferential side of the first member 214A of the shield portion 214, with the first member 214A as the boundary. The second member 214B of the shield portion 214 prevents the potential from spreading to the outer circumferential side of the shield portion 214. The analysis of the potential distribution shown in FIG. 14 reveals that the insulator 213 and the shield portion 214 effectively insulate the center conductor 211. Similar potential distribution results are obtained in the UW-phase bushing 100.

[0040] FIG. 15 is a diagram showing the results of analyzing the electric field distribution in the V-phase bushing 200. The electric field is stronger near the center conductor 211 and near the center of the center conductor 211. The electric field weakens with increasing distance from the center conductor 211. The electric field approaches zero on the outer periphery of the first member 214A of the shield portion 214, with the first member 214A as the boundary. The second member 214B of the shield portion 214 prevents the electric field from wrapping around the outer periphery of the shield portion 214. The analysis of the electric field distribution shown in FIG. 15 reveals that the insulator 213 and the shield portion 214 effectively insulate the center conductor 211. Similar electric field distribution results are obtained in the UW-phase bushing 100.

[0041] As described above, the UW-phase bushing 100 in the embodiment is a device that insulates the first central conductor 111 and the second central conductor 112 that electrically connect the instrument transformer VC and the gas-insulated switchgear G1. Similarly, the V-phase bushing 200 is a device that insulates the central conductor 211 that electrically connects the instrument transformer VC and the gas-insulated switchgear G1. The UW-phase bushing 100 includes the first central conductor 111 and the second central conductor 112 that pass through the center. Similarly, the V-phase bushing 200 includes the central conductor 211. The UW-phase bushing 100 includes an insulator 113 that is provided around the first central conductor 111 and serves as the main insulator. Similarly, the V-phase bushing 200 includes an insulator 213 that is provided around the central conductor 211 and serves as the main insulator. The UW-phase bushing 100 is provided within the insulator 113 at a distance from the first center conductor 111 and includes a metallic shield portion 114 that controls the electric field. Similarly, the V-phase bushing 200 is provided within the insulator 213 at a distance from the center conductor 211 and includes a metallic shield portion 214 that controls the electric field. The shield portion 114 includes a first member 114A that is formed in a cylindrical shape concentric with the first center conductor 111 and the second center conductor 112. Similarly, the shield portion 214 includes a first member 214A that is formed in a cylindrical shape concentric with the center conductor 211. The shield portion 114 includes a second member 114B that is provided at an open end of the first member 114A and that is formed in a spiral shape with the circumferential direction of the first member 114A as its axis. Similarly, the shield portion 214 includes a second member 214B that is provided at an open end of the first member 214A and that is formed in a spiral shape with the circumferential direction of the first member 214A as its axis.

[0042] This embodiment includes a shield portion 114 that has good adhesion to the insulator 113 and high resistance to deformation, and can provide a highly reliable UW-phase bushing 100. Similarly, this embodiment includes a shield portion 214 that has good adhesion to the insulator 213 and high resistance to deformation, and can provide a highly reliable V-phase bushing 200.

[0043] In the embodiment, the first member 114A of the shield portion 114 of the UW-phase bushing 100 is a mesh member. Similarly, the first member 214A of the shield portion 214 of the V-phase bushing 200 is a mesh member.

[0044] This embodiment can provide a UW-phase bushing 100 that includes a shield portion 114 that has high adhesion to the insulator 113. Similarly, this embodiment can provide a V-phase bushing 200 that includes a shield portion 214 that has high adhesion to the insulator 213.

[0045] In the embodiment, the insulator 113 of the UW-phase bushing 100 is made of resin. Similarly, the insulator 213 of the V-phase bushing 200 is made of resin. The mesh size of the first member 114A of the shield portion 114 of the UW-phase bushing 100 differs depending on whether the insulator 113 is made of a specific resin or a resin other than the specific resin. Similarly, the mesh size of the first member 214A of the shield portion 214 of the V-phase bushing 200 differs depending on whether the insulator 213 is made of a specific resin or a resin other than the specific resin.

[0046] This embodiment can provide a UW-phase bushing 100 that includes a shield portion 114 that has good adhesion to a desired resin even when the insulator 113 is made of a desired resin. Similarly, this embodiment can provide a V-phase bushing 200 that includes a shield portion 214 that has good adhesion to a desired resin even when the insulator 213 is made of a desired resin.

[0047] In the embodiment, the second member 114B of the shield portion 114 of the UW-phase bushing 100 is provided outside the first member 114A. Similarly, the second member 214B of the shield portion 214 of the V-phase bushing 200 is provided outside the first member 214A.

[0048] This embodiment can provide a UW-phase bushing 100 that includes a shield portion 114 that effectively controls the electric potential and electric field. Similarly, this embodiment can provide a V-phase bushing 200 that includes a shield portion 114 that effectively controls the electric potential and electric field.

[0049] In the embodiment, the insulator 113 of the UW-phase bushing 100 is made of resin. Similarly, the insulator 213 of the V-phase bushing 200 is made of resin. The first member 114A of the shield portion 114 of the UW-phase bushing 100 is tin-plated. Similarly, the first member 114A of the shield portion 214 of the V-phase bushing 200 is tin-plated.

[0050] This embodiment can provide a UW-phase bushing 100 that includes a shield portion 114 that has high adhesion to the insulator 113. Similarly, this embodiment can provide a V-phase bushing 200 that includes a shield portion 214 that has high adhesion to the insulator 213.

[0051] In the embodiment, the insulator 113 of the UW-phase bushing 100 is made of resin. Similarly, the insulator 213 of the V-phase bushing 200 is made of resin. The second member 114B of the shield portion 114 of the UW-phase bushing 100 is tin-plated. Similarly, the second member 214B of the shield portion 214 of the V-phase bushing 200 is tin-plated.

[0052] This embodiment can provide a UW-phase bushing 100 that includes a shield portion 114 that has high adhesion to the insulator 113. Similarly, this embodiment can provide a V-phase bushing 200 that includes a shield portion 214 that has high adhesion to the insulator 213.

[0053] In the embodiment, the UW-phase bushing 100 and the V-phase bushing 200 are provided to pass through an opening O1 formed in an upper bulkhead UB of the instrument transformer VC. The UW-phase bushing 100 is provided on an insulator 113 and includes a metal mounting portion 115 for mounting to the upper bulkhead UB. Similarly, the V-phase bushing 200 is provided on an insulator 213 and includes a metal mounting portion 215 for mounting to the upper bulkhead UB. The shield portion 114 of the UW-phase bushing 100 is provided between the first center conductor 111 and the mounting portion 115. Similarly, the shield portion 214 of the V-phase bushing 200 is provided between the center conductor 211 and the mounting portion 215.

[0054] This embodiment can provide a UW-phase bushing 100 that includes a shield portion 114 that effectively suppresses the influence of an electric field on the mounting portion 115. Similarly, this embodiment can provide a V-phase bushing 200 that includes a shield portion 214 that effectively suppresses the influence of an electric field on the mounting portion 215.

[0055] In the embodiment, the shield portion 114 of the UW-phase bushing 100 is provided closer to the instrument transformer VC in the axial direction of the first center conductor 111 and the second center conductor 112. Similarly, the shield portion 214 of the V-phase bushing 200 is provided closer to the instrument transformer VC in the axial direction of the center conductor 211.

[0056] This embodiment can provide a UW-phase bushing 100 that includes a shield portion 114 that more effectively suppresses the influence of electric fields on the side of the potential transformer VC. Similarly, this embodiment can provide a V-phase bushing 200 that includes a shield portion 214 that more effectively suppresses the influence of electric fields on the side of the potential transformer VC.

[0057] The UW-phase bushing 100 in the embodiment includes a plurality of mounting portions 115. Similarly, the V-phase bushing 200 includes a plurality of mounting portions 215. The plurality of mounting portions 115 of the UW-phase bushing 100 are spaced apart from one another and located concentrically with the first center conductor 111 and the second center conductor 112. Similarly, the plurality of mounting portions 215 of the V-phase bushing 200 are spaced apart from one another and located concentrically with the center conductor 211. The plurality of mounting portions 115 of the UW-phase bushing 100 are connected to the shield portion 114 using metal connecting members 117. Similarly, the plurality of mounting portions 215 of the V-phase bushing 200 are connected to the shield portion 214 using metal connecting members 217. The connecting members 117 of the UW-phase bushing 100 have the same length. Similarly, the connecting members 217 of the V-phase bushing 200 have the same length.

[0058] In this embodiment, the shield portion 114 is provided so that the distance between the first center conductor 111 and the shield portion 114 is uniform in the circumferential direction, thereby providing a UW-phase bushing 100 that effectively suppresses the influence of an electric field. Similarly, in this embodiment, the shield portion 214 is provided so that the distance between the center conductor 211 and the shield portion 214 is uniform in the circumferential direction, thereby providing a V-phase bushing 200 that effectively suppresses the influence of an electric field.

[0059] The shield portion 114 of the UW-phase bushing 100 in this embodiment is provided closer to the instrument transformer VC in the axial direction of the first center conductor 111 and the second center conductor 112, with the position of the attachment portion 115 as the reference. Similarly, the shield portion 214 of the V-phase bushing 200 is provided closer to the instrument transformer VC in the axial direction of the center conductor 211, with the position of the attachment portion 215 as the reference.

[0060] This embodiment can provide a UW-phase bushing 100 that includes a shield portion 114 that suppresses the influence of an electric field more effectively on the side of the instrument transformer VC than on the position of the mounting portion 115. Similarly, this embodiment can provide a V-phase bushing 200 that includes a shield portion 214 that suppresses the influence of an electric field more effectively on the side of the instrument transformer VC than on the position of the mounting portion 215.

[0061] In the embodiment, the UW-phase bushing 100 includes a bushing body 110. Similarly, the V-phase bushing 200 includes a bushing body 210. The UW-phase bushing 100 includes a current transformer terminal 130 for connection to the instrument transformer VC. Similarly, the V-phase bushing 200 includes a transformer terminal 230 for connection to the instrument transformer VC. The UW-phase bushing 100 includes a field relaxation conductor 140 that is provided between the bushing body 110 and the current transformer terminal 130 and relaxes the electric field relative to the current transformer terminal 130. Similarly, the V-phase bushing 200 includes a field relaxation conductor 240 that is provided between the bushing body 210 and the transformer terminal 230 and relaxes the electric field relative to the transformer terminal 230. The electric field relaxation conductor 140 of the UW-phase bushing 100 and the electric field relaxation conductor 240 of the V-phase bushing 200 are disk-shaped. The side surface of the electric field relaxation conductor 140 of the UW-phase bushing 100 protrudes outward beyond the current transformer terminal 130. Similarly, the side surface of the electric field relaxation conductor 240 of the V-phase bushing 200 protrudes outward beyond the transformer terminal 230.

[0062] This embodiment can provide a UW-phase bushing 100 that prevents the current transformer terminal 130 from shorting out with the tank T1 of the instrument transformer VC due to arcing, even without using any metal parts for leveling. Similarly, this embodiment can provide a V-phase bushing 200 that can prevent the transformer terminal 230 from shorting out with the tank T1 of the instrument transformer VC due to arcing, even without using any parts for leveling.

[0063] In the embodiment, the axial length of the bushing body 110 of the UW-phase bushing 100 is shorter than when the electric field relaxation conductor 140 is not provided. Similarly, the axial length of the bushing body 210 of the V-phase bushing 200 is shorter than when the electric field relaxation conductor 240 is not provided.

[0064] This embodiment can provide a UW-phase bushing 100 and a V-phase bushing 200 that can be easily leveled without using any parts for leveling.

[0065] In this embodiment, the current transformer terminal 130 of the UW-phase bushing 100 is connected to the current transformer C1 of the instrument transformer VC. The current transformer terminal 130 of the UW-phase bushing 100 has a rectangular plate shape bent into an L shape.

[0066] This embodiment provides a UW-phase bushing 100 that includes a current transformer terminal 130 with a simple configuration and that can reduce costs.

[0067] The UW-phase bushing 100 in the embodiment includes a first central conductor 111 that allows current to flow from the gas-insulated switchgear G1 to the instrument transformer VC. The UW-phase bushing 100 includes a second central conductor 112 that allows current to flow from the instrument transformer VC to the gas-insulated switchgear G1. The UW-phase bushing 100 includes a first L-shaped terminal 131 that serves as a current transformer terminal 130 and is connected to the first central conductor 111. The UW-phase bushing 100 includes a second L-shaped terminal 132 that serves as a current transformer terminal 130 and is connected to the second central conductor 112. The first L-shaped terminal 131 and the second L-shaped terminal 132 of the UW-phase bushing 100 are arranged so that the plate surfaces extending in the axial direction of the bushing main body 110 face each other.

[0068] This embodiment can provide a UW-phase bushing 100 that can be installed so that the plate surfaces of the terminals of the current transformer C1 and the plate surfaces of the first L-shaped terminal 131 and second L-shaped terminal 132 are parallel to a vertical plane.

[0069] In the UW-phase bushing 100 of the embodiment, the side surface of the electric field relaxation conductor 140 protrudes outward beyond the bent portions of the first L-shaped terminal 131 and the second L-shaped terminal 132 .

[0070] This embodiment can provide a UW-phase bushing 100 that prevents the first L-shaped terminal 131 and the second L-shaped terminal 132 from short-circuiting with the tank T1 of the instrument transformer VC due to arcing.

[0071] In this embodiment, transformer terminal 230 of V-phase bushing 200 is connected to transformer VT of instrument transformer VC. Center conductor 211 of V-phase bushing 200 has small diameter portion 211B having a diameter smaller than both end portions 211A.

[0072] This embodiment can increase the amount of resin in the insulator 213 without increasing the overall size, and can provide a V-phase bushing 200 with improved insulating effect.

[0073] The small diameter portion 211B of the central conductor 211 of the V-phase bushing 200 in the embodiment shown in FIG. 12 is formed over the entire area between the end portions 211A on both sides.

[0074] This embodiment can provide a V-phase bushing 200 in which the amount of resin in the insulator 213 is increased over the entire bushing body 210 .

[0075] In the embodiment shown in FIG. 12, the small diameter portion 211B of the central conductor 211 of the V-phase bushing 200 has a diameter that is 30% to 60% of the diameter of the end portion 211A.

[0076] This embodiment can provide a V-phase bushing 200 that has an improved insulating effect by increasing the amount of resin and that has excellent thermal and thermal performance and atmospheric power frequency voltage resistance performance.

[0077] In the embodiment shown in FIG. 13, a small diameter portion 211B of a central conductor 211 of a V-phase bushing 200 is formed closer to the gas-insulated switchgear G1 than the central portion in the axial direction.

[0078] In this embodiment, by making the diameter on the side of the instrument transformer VC rather than the central portion in the axial direction the same as the diameter of the end portion 211A, it is possible to provide a V-phase bushing 200 that has greater strength and stability than the structure shown in Figure 12.

[0079] In the embodiment shown in FIG. 13, the small diameter portion 211B of the central conductor 211 of the V-phase bushing 200 has a diameter that is 30% to 40% of the diameter of the end portion 211A.

[0080] This embodiment can provide a V-phase bushing 200 that has an improved insulating effect by increasing the amount of resin and that has excellent thermal and thermal performance and atmospheric power frequency voltage resistance performance.

[0081] Although the present invention has been described above using embodiments, the technical scope of the present invention is not limited to the scope described in the embodiments. It will be apparent to those skilled in the art that various modifications and improvements can be made to the embodiments. It is clear from the claims that such modifications and improvements can also be included within the technical scope of the present invention. [Explanation of symbols]

[0082] 100 UW phase bushing 100U U-phase bushing 100W W-phase bushing 110 Bushing body 111 First central conductor 112 Second central conductor 113 Insulator 113F flange 114 Shield part 114A First member 114B Second member 115 Mounting part 116 Interconductor insulator 117 Connecting member 120 Gas-insulated switchgear terminals 121 1st terminal section 122 2nd terminal section 130 Current transformer terminal 131 1st L-shaped terminal 132 2nd L-shaped terminal 140 Electric field relaxation conductor 200 V phase bushing 210 Bushing body 211 Center conductor 211A End 211B Small diameter section 213 Insulator 213F flange 214 Shield part 214A First member 214B Second member 215 Mounting part 217 Connecting members 220 Gas-insulated switchgear terminals 230 Transformer terminal 240 Electric field relaxation conductor C1 current transformer G1 Gas Insulated Switchgear O1 opening T1 Tank UB upper bulkhead VC instrument transformer VT transformer

Claims

1. 1. A bushing for insulating a conductor for electrically connecting an instrument transformer that monitors voltage and current in a gas-insulated switchgear to the gas-insulated switchgear, comprising: a bushing body; a terminal for connecting to the instrument transformer; an electric field relaxation conductor provided between the bushing body and the terminal, for relaxing an electric field relative to the terminal; the electric field relaxation conductor is disk-shaped, A bushing, wherein a side portion of the electric field buffer conductor projects outward beyond the terminal.

2. The bushing according to claim 1 , wherein the axial length of the bushing body is shorter than when the electric field relaxation conductor is not provided.

3. The terminals include current transformer terminals connected to the current transformers of the instrument transformers, 2. The bushing according to claim 1, wherein the current transformer terminal has a shape formed by bending a rectangular plate into an L-shape.

4. The conductor may be: a first central conductor for passing a current from the gas insulated switchgear to the instrument transformer; a second central conductor for passing current from the instrument transformer to the gas-insulated switchgear; The current transformer terminals include: a first L-shaped terminal connected to the first central conductor; a second L-shaped terminal connected to the second central conductor, The bushing according to claim 3 , wherein the first L-shaped terminal and the second L-shaped terminal are provided such that plate surfaces extending in the axial direction of the bushing body face each other.

5. 5. The bushing according to claim 4, wherein the side surface portion of the electric field buffer conductor projects outward beyond the bent portions of the first L-shaped terminal and the second L-shaped terminal.

6. The terminals include transformer terminals to be connected to the transformer of the instrument transformer, 2. The bushing according to claim 1, wherein the conductor has a small diameter portion having a diameter smaller than that of both end portions.

7. 7. The bushing of claim 6, wherein the reduced diameter portion is formed entirely between the opposite ends.

8. 8. The bushing of claim 7, wherein the reduced diameter portion has a diameter that is 30% to 60% of the diameter of the end portion.

9. 7. The bushing according to claim 6, wherein the small diameter portion is formed closer to the gas-insulated switchgear than a central portion in the axial direction.

10. 10. The bushing of claim 9, wherein the reduced diameter portion has a diameter that is 30% to 40% of the diameter of the end portion.

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