JPS62105320A - Bushing - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a bushing, and more particularly to an improvement in the ground shield of a bushing using an insulating gas as an insulating medium.

[Technical background of the invention and its problems]

In recent years, the dimensions of gas-insulated electrical equipment have been significantly reduced compared to conventional equipment by using an insulating medium with excellent insulating properties, such as an insulating gas such as SF or gas. Bushings are no exception; with the aim of reducing the installation area and weight, there is a growing demand for bushings that are compact and easy to handle. In addition, the length of the bushing is determined by the insulation class y4 and d/↑contamination specifications, so when downsizing, the diameter of the bushing must be reduced. Determined by the center conductor and the ground shield installed to improve potential distribution, the electric field at the center conductor and ground shield surfaces tends to increase as the diametrical dimension is reduced. For this reason, it has become necessary to arrange a grounding shield within a limited space without degrading insulation performance and so as to optimize the potential distribution of the bushing.

In a conventional bushing, a center conductor serving as a current-carrying conductor is inserted into a hollow insulator tube, and one end of the center conductor is fixed to the inside of a cover plate that is attached via an upper flange provided on the upper side of the insulator tube.

The lower flanges provided on the lower edge of the straddle pipe are airtightly fixed to the cylindrical grounding fittings via the annular grounding shield mounting members by 5, and as described later, the &-L and ``C grounding shields are grounded. It is attached to the shield mounting member.The inside of the insulator tube and the grounding fitting are insulating medium.
An insulating gas such as SFG gas is sealed. Further, an upper air shield is attached to the upper flange, and a lower air shield is attached to the lower flange.

The installation state of the ground shield in the conventional bushing) f is shown in Figure 5 1. It seems to show. That is, the F section flange 13b, which is attached to the lower end of the skeleton 11 by cementing 15, is attached to the cylindrical grounding fitting 17 so as to sandwich the annular grounding shield mounting member 16.
They are tightened and fixed together via the . At this time, a backing 19 is interposed between the end of the lower insulator 1 and the ground shield mounting member 16, and between the ground shield mounting member 16, respectively, to maintain airtightness. In addition, near the bottom of the center conductor 12 and the inner side of the insulator tube 11, a grounding shield holder which protrudes somewhat from the end of the insulator tube 11 is formed concentrically with the center conductor work 2 by means of a mounting bolt 26 on the upper side of the protrusion 16a of the member 16. A cylindrical ground shield 2:5 is attached.

The inner diameter of the insulator tube 11 above the tip of the grounding shield 25 inside the insulator tube 11 is φIJ, and the radius of the tip of the grounding shield 25 is
That is, the rounded portion 25a having a radius of curvature of the insulator tube 11
Let φA be the diameter to the end bent to the side, let Q□ be the interval for tolerance for installation work of the mounting bolt 26, and let φB be the diameter of the mounting bolt 26 on the insulator tube side, then φB
〉φB〉φA.

However, with the recent downsizing and weight reduction of equipment, the diameter of the insulator tube has been reduced, that is, the inner diameter of the insulator tube has been reduced due to the structure of mounting the ground shield. That is, the fastening space of the mounting bolt 25 is connected to the ground shield 25 and the insulator tube 1.
1, and as a result, the inner diameter of the grounding shield 25 is constrained to be small, so that the electric field on the inner surface and upper end surface of the grounding shield 25 and the surface electric field of the center conductor 12 facing the grounding shield 25 are It gets expensive. In particular, there is a problem in that a very high electric field is generated at the upper end of the grounding shield 25, degrading the insulation performance. In addition, the distance Q1 between the end of the mounting collar 27 of the grounding shield 25 and the end face of the insulator tube 11 becomes smaller, and there is a risk that the end face of the insulator tube 11 will be damaged due to dimensional errors in both the inner diameter of the insulator tube 11 and the grounding shield 25. .

[Purpose of the invention]

The present invention has been made in consideration of the above points, and its purpose is to make it possible to effectively utilize the intraosseous space when installing a grounding shield for improving potential distribution, and to reduce the size of the insular canal. Our objective is to provide bushings with improved insulation and insulation performance.

[Summary of the invention]

In order to achieve this object, according to the present invention, the grounding shield at the bottom of the insulator tube is fixed to the surface of the grounding shield mounting member opposite to the insulator tube via a mounting bolt, thereby reducing the size of the insulator tube. It is characterized by improved insulation and insulation performance.

[Embodiments of the invention]

Examples of the bushing of the present invention are shown in Figures 1 and 2 below.
The process will be explained with reference to the diagram. The same parts and parts having the same functions as those in FIG. 5 are given the same reference numerals. .

The bushing 10 is constructed as follows. The center conductor 12, which serves as a current-carrying conductor, is inserted into the hollow insulator 11 and is attached to the upper mounting flange 13a fixed to the upper part of the insulator 11 by cementing. One end of the conductor 12 is fixed.

Also, attach cement 15 to the R part of the insulator tube 11.
13h is the annular grounding shield mounting member 1.fi is also sandwiched between the 110il-shaped grounding fittings 17, and the bolts 18 are tightened and fixed 6. The plate 14 and the upper end surface of the insulator tube 11 are airtightly fixed through gaskets (!, f, not shown). A backing 19 is interposed between the grounding fitting I7 and the grounding fitting I7 to maintain airtightness.External shields 1, 3, and 13 are attached to the upper and f-section flanges 13a and 13b, respectively.

Further, a cylindrical grounding shield 20 is attached to the grounding seam II throat attachment portion iFA'16 via attachment bolts 21 as will be described later. The sides of the insulator tube 11 and the grounding fitting 17 are filled with a near insulating medium, for example, an insulating gas 10a such as SF or gas.

The manner in which the grounding shield '2Q' is attached to the grounding shield mounting member 1G will be described in detail. That is, the grounding shield mounting member 16 is formed in the shape of a single ring, that is, a circular ring, and is mounted with the protruding portion 16a protruding inside the insulation pipe 11 in the attached state.

The cylindrical ground shield ZO, which has an L-shaped cross section on one side, has one T-shaped mounting portion 21a fixed to the ground fitting 17 side of the ground shield mounting member 16 via a mounting bolt 21.

Now, the outer diameter of the larger attachment portion 21a of the ground shield 20 is assumed to be φBi. Then, a rounded part 20a having a radius of curvature is formed at the other end of the L-shape, that is, the end concentrically facing the center conductor 12, and the outer diameter of this rounded part 20a to the outer end is φA. . Also, -1 of this rounded part 20a
On the other hand, if the inner diameter of the nearby insulator tube 11 is φD, φB>
The relationship φD>φA holds, and the gap between the end of the rounded portion 20a and the inner wall of the insulator tube 11, that is, the distance Q2. is formed. L-shaped corner 20b of this grounding shield 20
Of course, the roundness is formed.

As described above, according to the configuration of the present invention, by fastening the grounding shield 20 to the surface of the grounding shield mounting member 16 opposite to the insulator tube 11 with the mounting bolt 21, the tightening position of the mounting bolt 21 can be adjusted to the insulator tube 11. The space inside the insulator tube 11 can be used effectively without being restricted by the inner diameter of the insulator tube 11. In addition, the electric field potential on the inner surface of the grounding shield 20 is kept low.
Furthermore, since the mounting bolt 21 of the grounding shield 20 is sufficiently far away from the center conductor 12, the surface of the mounting bolt z1 is The electric field can be relaxed.Furthermore, the production and installation work of the ground shield 20 is facilitated.

Furthermore, by attaching the mounting bolt 21 of the grounding shield 20 on the grounding metal fitting 17 side of the grounding shield mounting member 16, the conventional φD>φB is changed to φB1 in the embodiment of the present invention.
>φD (i,), there is plenty of room for mounting the mounting port 1-21. That is, there is no longer a restriction imposed by the conventional interval Q□ inside the insulator 11, and there is no risk of the interval expanding to Q2 and damaging the inner surface and end lfi of the insulator 11.

Next, a first alternative embodiment of the present invention will be described with reference to FIG. Parts having the same or the same functions as those in FIG. 2 are given the same reference numerals. That is, the corner 20b of the grounding shield 20
By forming a rounded shape.

Since the mounting bolt 21 is hidden behind the roundness of the corner 20b and does not directly face the center conductor 12, the electric field on the surface of the mounting bolt 1-21 can be further relaxed than in the embodiment of the present invention. can. To explain in detail again, the grounding shield 20 is attached to the grounding metal fitting 17 side of the grounding shield attachment member 16 with the attachment bolt 21 so that the attachment bolt 21 does not directly oppose the center conductor 12.

The roundness of the corner 20b of the grounding shield 20 is determined by the distance from the surface of the grounding shield mounting member 16 on the grounding fitting 17 side to the end face of the corner 20b of the grounding shield 20 +4, as shown in the figure.
．． However, the mounting bolt 2 is removed from the surface of the ground shield mounting member 16.
Distance to end face of 1! (6) Next, a second embodiment of the present invention will be explained with reference to FIG. 4. Portions that are the same as those in FIG. In other words, by providing an insulating film 22 on the surface of the grounding shield 20 other than the parallel surface facing the center conductor 12, the space near the end surface of the grounding shield 20 is Insulation performance can be improved against electric field concentration due to sudden changes in electric field distribution.

This insulating film 22 is preferably formed of an alumite film by alumite treatment. With this configuration, the insulation property, that is, the voltage resistance can be further improved than in the first other embodiment of the present invention.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to construct a grounding shield with good insulation performance, to reduce the inner diameter of the insulator tube, and to provide a small and lightweight bushing with good insulation performance.

[Brief explanation of drawings]

FIG. 1 is a sectional view of the bushing of the present invention, FIG. 2 is a sectional view of the main part of FIG. 1, FIG. 3 is a sectional view of the main part of the first other embodiment of the invention, and FIG. 5 is a cross-sectional view of the main part of a second alternative embodiment of the present invention, and FIG. 5 is a cross-sectional view of the main part of a conventional bushing. 10...Bushing, 10a...Insulating gas, 11.
...Insulator tube. 12...Center conductor, ]3...Outer shield. 13a, 13b...upper and lower mounting flanges, 14
...Lid plate. 15... Cementing, 16... Grounding shield mounting member. 17...Grounding metal fitting, 18...Bolt, 19...Backing. 20...Grounding shield, 200...Me 1 junction, 71
'li, Corner 21...Mounting bolt, 213...Mounting part. 22...Insulating film.

Claims (4)

[Claims] (1) A center conductor is inserted coaxially into the tube filled with an insulating medium, and a cylindrical ground shield is provided on the ground side of the insulator tube so as to be coaxial with the outer periphery of the center conductor. In the bushing attached to the grounding shield mounting member, the mounting part of the grounding shield having an L-shaped cross section on one side is attached to the surface of the grounding shield mounting member opposite to the insulator tube via a mounting bolt. A bushing characterized by having a rounded corner and a rounded corner. (2) The bushing according to claim 1, wherein the ground shield has rounded corners so that the tip of the mounting bolt does not directly oppose the center conductor. (3) The bushing according to claim 1 or 2, wherein the ground shield has an insulating film covering the rounded portion and corner portion of the tip other than the ground shield surface facing the center conductor. (4) The bushing according to claim 3, wherein the insulating film is formed of an alumite film.