Bushing structure and electric apparatus

Abstract

A ground shield (3) is configured to have: a cylindrical part (31) positioned coaxially on the outer peripheral side of a porcelain tube inner conductor (2); and an extension part (32) having a shape extending outward in the radial direction of a porcelain tube (1) from the cylindrical part (31) and interposed between a porcelain tube-side flange (4) and a container-side flange (6). A notch recess (7) having a shape capable of receiving at least an extension-direction end part (35) side of the extension part (32) is provided in one of: an inner peripheral side part (4a) of a porcelain tube-side opposing surface of an opposing surface (40) of the porcelain tube-side flange (4); and an inner peripheral side part (6a) of a container-side opposing surface of an opposing surface (60) of the container-side flange (6). The extension part (32) is configured such that, in a state of being supported on the inner peripheral side part (4a) of the porcelain tube-side opposing surface, at least the extension-direction end part (35) side of the extension part (32) is received in the notch recess.

Description

Bushing structures and electrical equipment

[0001] The present invention relates to a bushing structure and an electric device, and more particularly to a technique applicable when connecting an electric device such as a circuit breaker or a switchgear to a main circuit.

[0002] BACKGROUND ART It is known that electrical equipment such as circuit breakers and switchgears in power facilities are electrically connected to a main circuit or the like via a bushing (gas insulating bushing or the like).

[0003] The bushing structures shown in Patent Documents 1 and 2 are configured to include a conductor within a cylindrical porcelain tube that extends along the axis of the porcelain tube (hereinafter simply referred to as the porcelain tube axis), and a cylindrical grounding shield that is coaxially arranged within the porcelain tube on the outer periphery of the conductor within the porcelain tube.

[0004] In addition, a porcelain tube side flange is provided at one opening (hereinafter simply referred to as one-side opening) in the porcelain tube in the direction of both ends of the porcelain tube axis (hereinafter simply referred to as the porcelain tube both-end direction), and a container side flange is provided at a bushing communication port that can communicate with the one-side opening in an electrical equipment container (for example, a container such as a grounded tank that can accommodate electrical equipment elements such as a vacuum interrupter or a disconnecting switch (including a mode in which compressed air or the like is blown onto an arc generating part when the circuit is opened); hereinafter simply referred to as the container), and the porcelain tube side flange and the container side flange are configured to be flange-joined to each other.

[0005] In the case of the grounding shield of Patent Document 1, it is supported by a flange dedicated to the grounding shield (the flange indicated by the symbol 8 in Patent Document 1) interposed between the porcelain tube side flange and the container side flange.

[0006] The ground shield of Patent Document 2 is configured to be supported by a flange on the vessel side (the flange designated by reference numeral 5A in Patent Document 2).

[0007] JP-A No. 9-27225 JP-A No. 7-21861

[0008] The bushing structure disclosed in Patent Document 1 requires a flange dedicated to the grounding shield in addition to the porcelain tube flange and the container flange, which increases the number of parts, and therefore increases the number of assembly steps, which may lead to an increase in the size, complexity, and cost of the structure.

[0009] In the bushing structure disclosed in Patent Document 2, the container flange is supported by the ground shield, and then the container flange and the porcelain tube flange are flange-joined to connect one opening of the porcelain tube to the bushing communication opening. Therefore, for example, if the ground shield is positioned close to the inner peripheral surface of the porcelain tube, the inner peripheral surface of the porcelain tube and the ground shield are likely to interfere (contact, collision, misalignment, etc.) during flange joining. Assembling the bushing structure while preventing such interference between the two can be complex and difficult (making the flange joining process difficult).

[0010] The present invention has been made in consideration of the above-mentioned technical problems, and aims to provide a technique that can contribute to reducing the number of parts in a bushing structure and facilitating assembly.

[0011] A bushing structure according to one aspect of the present invention includes a cylindrical porcelain bushing, a conductor disposed within the porcelain bushing so as to extend along the axis of the porcelain bushing, a cylindrical grounding shield disposed within the porcelain bushing coaxially around the conductor, an annular porcelain bushing flange disposed at an opening of the porcelain bushing on one side of the axial center, and an annular container flange disposed at a bushing communication opening that can communicate with the opening of a container of an electrical device and is flange-joined to the porcelain bushing flange. The grounding shield includes a cylindrical portion disposed coaxially around the conductor and extending from the cylindrical portion radially outward of the porcelain bushing and interposed between the porcelain bushing flange and the container flange. A notched recess is provided on one of an inner peripheral portion of the surface of the porcelain tube-side flange facing the container-side flange, which is on the radially inner side, and an inner peripheral portion of the surface of the container-side flange facing the porcelain tube-side flange, which is on the radially inner side. The notched recess is open to the other of the two sides and to the axis center, and extends in the circumferential direction of the axis center. The extending portion is supported by the inner peripheral portion of the porcelain tube-side facing surface, and at least the extending end side of the extending portion is received in the notched recess.

[0012] Furthermore, the extension portion is supported by being fastened to the inner peripheral side of the opposing surface on the porcelain tube side via a shield fastening member that can fasten the extension portion to the inner peripheral side of the opposing surface on the porcelain tube side, and the shield fastening member has a protruding portion that protrudes from the extension portion toward the inner peripheral side of the opposing surface on the container side when the extension portion is fastened, and the cutout recess may be shaped to accommodate at least the end side of the extension portion in the extension direction and the protruding portion of the shield fastening member when the extension portion is fastened.

[0013] The container flange and the bushing communication opening may be separate bodies.

[0014] The electrical wiring may further comprise a current detector having an annular core through which the bushing communication opening passes and capable of detecting a current flowing through the conductor inside the insulator tube.

[0015] Furthermore, the porcelain tube side flange outer peripheral side portion, which is on the radially outer side of the porcelain tube side flange, and the container side flange outer peripheral side portion, which is on the radially outer side of the container side flange, may be fastened and fixed by a flange fastening member capable of fastening the porcelain tube side flange outer peripheral side portion and the container side flange outer peripheral side portion together.

[0016] One aspect of the electrical equipment is an electrical equipment provided with any of the above bushing structures, characterized in that at least one of a vacuum interrupter and a circuit breaker is electrically connected to the conductor inside the insulator tube while being housed in the container.

[0017] As described above, the present invention can contribute to reducing the number of parts in a bushing and facilitating assembly.

[0018] 1 is a schematic diagram illustrating the bushing structure according to Example 1 (a cross-sectional view taken along the axis of the porcelain tube); FIG. 4 is a schematic diagram illustrating an enlarged view of a main portion of FIG. 1; FIG. 2 is a schematic diagram illustrating an enlarged view of a main portion of FIG. 2 ((a) is a view showing the porcelain tube side flange 4 and the container side flange 6 in a flange-joined state, and (b) is a view showing only the porcelain tube side flange 4 and the container side flange 6 before the flange-joining); FIG. 4 is a schematic diagram illustrating the bushing structure according to Example 2 (a cross-sectional view taken along the axis of the porcelain tube); FIG. 5 is a schematic diagram illustrating an enlarged view of a main portion of FIG.

[0019] The bushing structure and electrical equipment of the embodiments of the present invention are completely different from configurations such as those described in Patent Document 1, in which the ground shield is supported on a flange dedicated to the ground shield, or those described in Patent Document 2, in which the ground shield is supported on a container-side flange.

[0020] That is, in this embodiment, the ground shield has a cylindrical portion that is positioned coaxially on the outer periphery of the conductor inside the porcelain tube, and an extension portion (hereinafter simply referred to as the shield extension portion) that extends outward from the cylindrical portion in the radial direction of the porcelain tube (hereinafter simply referred to as the porcelain tube radial direction) and is interposed between the porcelain tube side flange and the container side flange.

[0021] In addition, a cutout recess having a shape capable of accepting at least the extension direction end side of the shield extension portion is provided in one of the following areas: a portion of the surface of the porcelain tube side flange facing the container side flange that is inside in the porcelain tube radial direction (hereinafter simply referred to as the inner peripheral side portion of the porcelain tube side facing surface), and a portion of the surface of the container side flange facing the porcelain tube side flange that is inside in the porcelain tube radial direction (hereinafter simply referred to as the inner peripheral side portion of the container side facing surface).

[0022] The shield extension is supported by the inner peripheral side of the facing surface of the porcelain insulator tube, and at least the end of the shield extension in the extension direction is received in the cutout recess.

[0023] According to the configuration of this embodiment, a flange dedicated to the ground shield is not required, which reduces the number of parts and assembly steps, contributing to a smaller, simpler, and less expensive structure.

[0024] Furthermore, when the bushing flange is flange-joined to the vessel flange with the shield extension already supported on the inner peripheral side of the bushing flange, at least the end of the shield extension in the extension direction can be received in the notched recess. Therefore, even when the bushing flange is flange-joined to the vessel flange, interference between the shield extension and the vessel flange can be prevented, and interference (contact, collision, misalignment, etc.) between the inner peripheral surface of the bushing and the ground shield can also be prevented. This facilitates assembly of the bushing structure as desired (facilitating flange joining).

[0025] The bushing structure and electrical equipment of this embodiment can be modified in various ways as long as the shield extension portion can be supported on the inner peripheral side of the surface facing the porcelain tube as described above and at least the extension direction end side of the shield extension portion can be received within the cutout recess.

[0026] That is, it is possible to appropriately apply common technical knowledge in various fields (for example, the field of bushings, circuit breakers, switchgears, and power equipment) and, as necessary, to appropriately refer to prior art documents and the like to modify the design, examples of which are given in Examples 1 and 2 below.

[0027] 1 to 3 are schematic diagrams illustrating a bushing structure according to a first embodiment, showing an example in which the bushing structure is provided in a container 10 of an electrical device such as a circuit breaker or a switchgear.

[0028] In the bushing structure shown in Figures 1 to 3, a conductor 2 inside the insulating cylindrical porcelain tube 1 is provided so as to extend along the axis, and a cylindrical grounding shield 3 is further provided so as to be positioned coaxially on the outer periphery of the conductor 2 inside the porcelain tube.

[0029] In the porcelain tube 1, a circular porcelain tube side flange 4 is provided at one side opening 11 located on one side (the lower side in the figure) in the direction of both ends of the porcelain tube, and a circular connecting flange 13 is provided at an opening (hereinafter simply referred to as the other side opening) 12 on the other side (the upper side in the figure) in the direction of both ends of the porcelain tube.

[0030] The other opening 12 is sealed by providing a conductive sealing end plate 14 on the connection flange 13, which makes it possible to suppress leakage of, for example, the insulating gas sealed in the porcelain tube 1. The sealing end plate 14 is electrically connected, for example, to the main circuit side of an electric power facility (not shown).

[0031] The one side opening 11 is in communication with the bushing communication port 5 of the container 10 by flange-joining the porcelain tube side flange 4 to the annular container side flange 6 provided at the bushing communication port 5 .

[0032] [Example of Porcelain Tube 1] The porcelain tube 1 may be, for example, a tube formed into a cylindrical shape using an insulating polymer material or a porcelain material. In the case of the porcelain tube 1 shown in FIGS. 1 to 3, the outer surface of a cylindrical inner wall portion 1a made of a polymer material is covered with a cylindrical outer wall 1b made of the same polymer material, forming a two-layer structure. However, this is not limiting. For example, a single-layer structure may be used, as shown in FIGS. 4 and 5 (described later). Furthermore, the outer surface of the porcelain tube 1 may have a bellows shape by providing a plurality of annular fins 1c extending circumferentially along the outer surface of the outer wall 1b, as in the outer wall 1b shown in FIGS. 1 to 3.

[0033] [Example of the conductor 2 inside the insulator tube] The conductor 2 inside the insulator tube may be, for example, formed into a wire shape using a conductive material. In the case of the conductor 2 inside the insulator tube shown in Figures 1 to 3, an end 21 on one end side is joined to a conductor inside the container 10 (for example, the in-container conductor 10b in Figures 4 and 5 described below), and an end 22 on the other end side is joined to and supported by the center of the sealed end plate 14. This allows electrical equipment elements such as a vacuum interrupter or circuit breaker (not shown) placed inside the container 10 to be electrically connected to, for example, the main circuit side of a power facility (not shown).

[0034] [Example of Grounding Shield 3] The grounding shield 3 may be, for example, a conductive material suitably molded into a cylindrical shape, etc. The grounding shield 3 shown in Figures 1 to 3 has a cylindrical portion 31 positioned coaxially with the outer periphery of the conductor 2 inside the insulator tube, and a flange-shaped shield extension portion 32 extending radially outward from the cylindrical portion 31.

[0035] 1 to 3, the shield extension 32 has a shape that extends outward in the radial direction of the porcelain insulator tube from the open end 33 on one side of the tubular portion 31 in the direction of both ends of the porcelain insulator tube, but is not limited to this. For example, the shield extension 32 may have a shape that extends outward in the radial direction of the porcelain insulator tube from the center of the tubular portion 31 in the direction of both ends of the porcelain insulator tube.

[0036] Furthermore, at the open end 34 on the other side of the tubular portion 31 in the direction of both ends of the porcelain insulator, the end 34a side may be curved and expanded outward in the radial direction of the porcelain insulator, as shown in the figure, in order to further alleviate the electric field at the open end 34. Specifically, in the case of the open end 34 shown in the figure, the end 34a side expands outward in the radial direction of the porcelain insulator, while curving back in the opposite direction to the extension direction of the open end 34 itself, so as to approach the open end 34 itself.

[0037] The shield extension portion 32 is interposed between the porcelain tube side flange 4 and the container side flange 6, and is supported by the porcelain tube side flange 4. Specifically, the shield extension portion 32 is supported by an inner peripheral side portion 4a of the porcelain tube side facing surface 40 of the porcelain tube side flange 4 facing the container side flange 6, which is on the inner side in the porcelain tube radial direction. In addition, in this supported state, at least the extension direction end portion 35 side of the shield extension portion 32 is received in a cutout recess 7 described below.

[0038] Furthermore, the ground shield 3 and the inner peripheral surface of the porcelain tube 1 are appropriately set so as not to come into contact with each other. Specifically, the dimensions of the ground shield 3 (e.g., the dimension in the radial direction of the porcelain tube) and the support position of the shield extension 32 relative to the porcelain tube-side flange 4 are appropriately set to form a small gap between the ground shield 3 and the inner peripheral surface of the porcelain tube 1 as shown in the drawing.

[0039] [Examples of the porcelain bushing flange 4, the container flange 6, and the connection flange 13] The porcelain bushing flange 4, the container flange 6, and the connection flange 13 may each be suitably formed into a circular ring shape using a conductive material, for example.

[0040] 1 to 3, the porcelain tube-side flange 4 has a flange portion 41 that extends outward in the porcelain tube radial direction from one side opening 11 and extends circumferentially about the porcelain tube axis, and a tubular portion 42 that extends from the inner peripheral side of the flange portion 41 to the other side along the outer peripheral surface of the porcelain tube 1 in the direction of both ends of the porcelain tube. A reduced-diameter portion 43 having a smaller diameter than the inner peripheral surface of the tubular portion 42 is formed on the inner peripheral side of the flange portion 41. As a result, the one-side opening 11 of the porcelain tube 1 is fitted between the inner peripheral surface of the tubular portion 42 and the reduced-diameter portion 43 (on the inner angle side) and supported.

[0041] The connection flange 13 has a configuration similar to that of the porcelain tube-side flange 4, and includes a flange portion 13a extending outward in the porcelain tube radial direction from the other-side opening 12 and extending circumferentially about the porcelain tube axis, and a tubular portion 13b extending from the inner peripheral side of the flange portion 13a along the outer peripheral surface of the porcelain tube 1 to one side in the direction of both ends of the porcelain tube. A reduced-diameter portion 13c having a smaller diameter than the inner peripheral surface of the tubular portion 13b is formed on the inner peripheral side of the flange portion 13a. As a result, the other-side opening 12 of the porcelain tube 1 is fitted between the inner peripheral surface of the tubular portion 13b and the reduced-diameter portion 13c (on the inner angle side) and supported.

[0042] The container side flange 6 has a flange portion 61 that extends inward and outward in the radial direction of the porcelain tube from the opening end 51 on the other side of the bushing communication port 5 in the direction of both ends of the porcelain tube, and extends circumferentially around the porcelain tube axis.

[0043] A notched recess 7 is provided on an inner peripheral side 6a of the container-side flange 6, which is on the inner side in the radial direction of the porcelain tube, of the surface 60 of the container-side flange 6 that faces the porcelain tube-side flange 4. This notched recess 7 has a shape that can receive at least the extension direction end 35 of the shield extension portion 32 when the shield extension portion 32 is supported by the porcelain tube-side flange 4. The shape of the notched recess 7 may be any shape that can receive at least the extension direction end 35 of the shield extension portion 32 as described above, and can be set appropriately (for example, the dimensions in the directions toward both ends of the porcelain tube or the dimensions in the radial direction of the porcelain tube may be set appropriately).

[0044] 2, when the shield extension 32 is fastened and supported to the inner peripheral side portion 4a of the surface facing the porcelain insulator tube by a fastening member 36 having a bolt 36a, and a portion of the fastening member 36 (such as a screw head 36b in the figure) protrudes from the shield extension 32 to one side toward both ends of the porcelain insulator tube, the cutout recess 7 may have a shape that can receive at least the extension direction end 35 side of the shield extension 32 and the protruding portion (hereinafter simply referred to as the protruding portion). Specifically, in the case of the cutout recess 7 in FIGS. 1 to 3, a receiving hole 71 shaped to be able to receive the protruding portion of the fastening member 36 is provided in a position on the inner peripheral surface of the cutout recess 7 that faces the fastening member 36.

[0045] [Example of Container 10] The container 10 may be, for example, a metal material suitably molded into a housing shape or the like (for example, a grounded tank, etc.) The container 10 contains at least one electrical device element (not shown), such as a vacuum interrupter or disconnecting switch (including a device in which compressed air or the like is blown onto an arc generating portion to extinguish an arc when the circuit is opened) that is used in electrical devices such as circuit breakers (including gas circuit breakers, etc.) and switchgears, and is filled with insulating gas.

[0046] The bushing communication opening 5 provided in the container 10 can be formed as appropriate depending on the intended electrical equipment. The bushing communication opening 5 shown in Figures 1 to 3 has a cylindrical side wall 50, and a container-side flange 6 is integrally formed at the other open end 51 of the side wall 50 in the direction of both ends of the porcelain bushing.

[0047] [Others] The elements of the bushing structure of Example 1 can be joined and fixed or integrally formed using various joining means (adhesives, fastening members, welding, etc.), or can be assembled appropriately by disposing a sealing material in a predetermined position (for example, disposing a sealing material S as shown in Figures 4 and 5 described below).

[0048] The joining means is not particularly limited, and any means suitable for fixing each element of the bushing structure may be used.

[0049] 1 to 3, for example, the porcelain tube flange 4 and the connection flange 13 are bonded and fixed to the porcelain tube 1 (one-side opening 11, the other-side opening 12) with an adhesive (not shown). In addition, the outer peripheries of both the connection flange 13 and the sealing end plate 14 are fastened and fixed by fastening members 15 having bolts 15a and nuts 15b.

[0050] The outer peripheries of both the porcelain tube side flange 4 and the container side flange 6 (the porcelain tube side flange outer periphery side portion 4b and the container side flange outer periphery side portion 6b) are fastened and fixed by fastening members 16 having bolts 16a.

[0051] According to the above-described embodiment 1, a dedicated flange for the ground shield as in, for example, Patent Document 1 is not required, which reduces the number of parts and assembly steps, and contributes to miniaturization, simplification, and cost reduction of the structure.

[0052] Furthermore, even if the shield extension 32 is supported on the porcelain tube flange 4 in advance and then the porcelain tube flange 4 is flange-joined to the container flange 6, at least the extension direction end 35 of the shield extension 32 can be received in the cutout recess 7. This prevents interference between the shield extension 32 and the container flange 6, and also prevents interference (contact, collision, misalignment, etc.) between the inner peripheral surface of the porcelain tube 1 and the ground shield 3. As a result, the bushing structure can be easily assembled as desired.

[0053] 4 and 5 are schematic diagrams illustrating a bushing structure according to a second embodiment, showing an example of a case where the bushing structure is provided in the container 10, similar to the first embodiment. Note that the same components as those in the first embodiment will be denoted by the same reference numerals, and detailed descriptions thereof will be omitted as appropriate.

[0054] [Example of bushing communication port 5 and current detector 8] The bushing communication port 5 shown in Figures 4 and 5 is configured separately from the container side flange 6 and is configured to allow the installation of a current detector 8.

[0055] Specifically, the side wall 50 of the bushing communication opening 5 stands on the opening edge of a through hole 10 c formed through the peripheral wall 10 a of the container 10 .

[0056] The current detector 8 has an annular core 80 capable of detecting a current flowing on the axial side. The annular core 80 is disposed between the container 10 and the open end 51 on the outer periphery of the side wall 50, with the side wall 50 penetrating the axial side of the annular core 80.

[0057] The container-side flange 6 is supported on the open end 51 of the side wall 50 via an annular connection adapter 52 provided on the open end 51. In the case of the container-side flange 6 shown in Figures 4 and 5, fastening holes 82 for fastening members (not shown) are provided on the outer periphery of the container-side flange 6 so as to support a protective cover 81 that can cover the outer periphery of the annular core 80.

[0058] [Others] As with the first embodiment, the elements of the bushing structure of the second embodiment can be joined and fixed or integrally molded using various joining means (adhesives, fastening members, welding, etc.), or can be assembled appropriately by disposing a sealing material S in a predetermined position, etc.

[0059] 4 and 5, for example, the sealing end plate 14 has a seal groove 14b extending circumferentially around the axial center of the insulator tube on a joining surface 14a with the connection flange 13. The sealing end plate 14, with a seal material S such as an O-ring disposed in the seal groove 14b, is joined and fixed to the connection flange 13 via an adhesive (not shown).

[0060] The container-side flange 6 is fastened and fixed to the connection adapter 52 by a fastening member 53 having a bolt 53a.

[0061] 4 and 5, a receiving hole 72 shaped to receive the screw head 53b of the bolt 53a is provided at the fastening position of the fastening member 53 on the inner peripheral surface of the cutout recess 7. As a result, when the container-side flange 6 and the connection adapter 52 are fastened with the fastening member 53, the screw head 53b of the bolt 53a can be received in the receiving hole 72, so that, for example, interference between the shield extension 32 and the screw head 53b can be prevented.

[0062] In addition, a seal groove 62 extending circumferentially around the porcelain tube axis is provided on the opposing surface 60 of the container side flange 6 at a position between the cutout recess 7 and the fastening member 16, and a seal material S is arranged in the seal groove 62.

[0063] In addition, a seal groove 64 extending circumferentially around the porcelain tube axis is provided on the joint surface 63 of the container side flange 6 with the connection adapter 52, and a seal material S is arranged in the seal groove 64.

[0064] 4 and 5, the positional relationship between the seal groove (and seal material S) 64 and the fastening member 53 is depicted as being interchanged, but either positional relationship may be applied.

[0065] According to the second embodiment described above, in addition to the same effects as those of the first embodiment, the following can be said: Since the bushing communication port 5 and the container-side flange 6 are configured separately, the annular core 80 of the current detector 8 can be appropriately positioned on the outer periphery of the bushing communication port 5 before joining them. This allows the annular core 80 to have an inner diameter smaller than the outer diameter of the container-side flange 6, which may contribute to the miniaturization, simplification, and cost reduction of the bushing structure.

[0066] Although the present invention has been described in detail above only with respect to the specific examples, it will be apparent to those skilled in the art that various modifications are possible within the scope of the technical concept of the present invention, and it is natural that such modifications fall within the scope of the claims.

[0067] For example, instead of forming the notched recess 7 on the inner peripheral side portion 6a of the container-side facing surface of the facing surface 60 as shown in Figures 1 to 5, the notched recess 7 may be formed on the inner peripheral side portion 4a of the porcelain tube-side facing surface of the facing surface 40. Even in this case, the shield extension portion 32 can be supported on the porcelain tube-side flange 4 in advance (supported on the inner peripheral surface of the notched recess 7), and the porcelain tube-side flange 4 can be flange-joined to the container-side flange 6, and at least the extension direction end portion 35 of the shield extension portion 32 can be received within the notched recess 7. This makes it possible to achieve the same effects as those of Examples 1 and 2.

[0068] DESCRIPTION OF SYMBOLS 1... Porcelain tube 2... Conductor inside porcelain tube 3... Grounding shield 32... Extension portion 35... Extension direction end portion 4... Porcelain tube side flange 5... Bushing communication port portion 6... Housing side flange 7... Notched recess 8... Current detector 10... Container (grounded tank, etc.)

Claims

1. A cylindrical porcelain tube, a conductor within the porcelain tube extending along the axis of the porcelain tube, a cylindrical grounding shield disposed within the porcelain tube coaxially on the outer periphery of the conductor within the porcelain tube, an annular porcelain tube side flange disposed at an opening on one side of both ends of the axis of the porcelain tube, and an annular container side flange disposed at a bushing communication port capable of communicating with the opening in a container of an electrical device and flange-joined to the porcelain tube side flange, wherein the grounding shield comprises a cylindrical portion located coaxially on the outer periphery of the conductor within the porcelain tube, and an extension portion extending from the cylindrical portion radially outward of the porcelain tube and interposed between the porcelain tube side flange and the container side flange, A bushing structure characterized in that a cutout recess is provided on one of the inner circumferential side portion of the porcelain tube side facing surface of the porcelain tube side flange, which is the radially inner side of the surface of the porcelain tube side flange facing the container side flange, and the inner circumferential side portion of the container side facing surface of the container side flange, which is the radially inner side of the surface of the porcelain tube side flange facing the container side flange, the cutout recess is open to the other of the two sides and to the axis center side, and extends circumferentially along the axis center, and the extension portion is supported by the inner circumferential side portion of the porcelain tube side facing surface, and at least the extension direction end side of the extension portion is received within the cutout recess.

2. The bushing structure described in claim 1, characterized in that the extension portion is supported by being fastened to the inner periphery of the opposing surface on the porcelain tube side via a shield fastening member that can fasten the extension portion to the inner periphery of the opposing surface on the porcelain tube side, the shield fastening member has a protruding portion that protrudes from the extension portion toward the inner periphery of the opposing surface on the container side when the extension portion is fastened, and the cutout recess is shaped to be able to receive at least the extension direction end side of the extension portion and the protruding portion of the shield fastening member when the extension portion is fastened.

3. A bushing structure according to claim 1, wherein the container side flange and the bushing communication opening are separate bodies.

4. A bushing structure according to claim 3, further comprising a current detector having an annular core through which the bushing communication opening passes and capable of detecting a current flowing through the conductor inside the porcelain tube.

5. A bushing structure as described in claim 1, characterized in that the outer circumferential side portion of the porcelain tube side flange, which is the radially outer side of the porcelain tube side flange, and the outer circumferential side portion of the container side flange, which is the radially outer side of the container side flange, are fastened and fixed by a flange fastening member capable of fastening the outer circumferential side portion of the porcelain tube side flange and the outer circumferential side portion of the container side flange.

6. An electrical device provided with a bushing structure according to any one of claims 1 to 5, characterized in that at least one of a vacuum interrupter and a disconnecting switch is electrically connected to the conductor in the porcelain tube while being housed in the container.

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