JPS63126122A - Gas 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 [Object of the Invention] (Industrial Field of Application) The present invention particularly relates to a gas bushing using an insulating gas as an insulating medium.

(Prior Art) 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 SF6 gas. Bushings are no exception, and with the aim of reducing the installation area and weight, there is a desire for bushings that are more and more compact and easy to handle.

By the way, since the length of the bushing is determined by the insulation class and antifouling specifications, when downsizing the bushing, the goal is to reduce the diameter of the bushing. In addition, the insulation strength inside the bushing is determined by the center conductor, which is a current-carrying conductor, and the ground shield, which is installed to improve potential distribution. The electric field tends to rise. For this reason,
without reducing insulation performance in a limited space.
In addition, it has become necessary to arrange a grounding shield so that the potential distribution of the bushing is appropriate.

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

Further, the lower flanges provided on the lower edge of the insulator tube are airtightly fixed to the cylindrical grounding fittings via the annular grounding shield mounting member, and the grounding shield is attached to the mounting member as described later. Then, an insulating gas such as SF6 gas is filled as an insulating medium inside the porcelain tube and the grounding fitting. Further, an upper air shield is attached to the upper flange provided on the upper side of the insulator tube, and a lower air shield is attached to the lower flange.

In the conventional bushing described above, the state in which the ground shield is attached is as shown in FIG. In other words, insulator 1
A lower flange 13b fixed to the lower end of the cylindrical grounding fitting 17 by cementing 15 is fixedly fixed to the cylindrical grounding fitting 17 via bolts 18 so as to sandwich the annular grounding shield mounting member 16 therebetween.

At this time, a backing 19 is interposed between the end of the insulator tube 11 and the ground shield mounting member 16 and between the ground fitting 17 and the ground shield mounting member 16, respectively, to maintain airtightness. Further, near the lower part of the inner side of the center conductor 12 and the insulator tube 11, a cylindrical shape is formed concentrically with the center conductor 12 by means of a mounting bolt 26 on the upper side of the protrusion 16a of the grounding shield mounting member 16 that protrudes somewhat from the end of the insulator tube 11. A ground shield 25 is attached.

Insulator tube 11 above the tip of grounding shield 25 inside insulator tube 11
The inner diameter of the grounding shield 25 is φD, the radius of the rounded portion 25a having a radius of curvature to the end bent toward the insulator tube 11 is φA, and the tolerance of the installation work of the mounting bolt 26 is φD. When the interval for the mounting bolt 26 is 11 and the diameter of the insulator tube side of this mounting bolt 26 is φB, φO〉φB〉
It is formed to have a relationship of φA.

However, with the recent downsizing of equipment to 2 meters, the reduction in the diameter of the insulator tube, that is, the reduction in the inner diameter of the insulator tube, is subject to restrictions due to the ground shield mounting structure. That is, a fastening space for the mounting bolt 26 must be provided between the grounding shield 25 and the insulator tube 11, and as a result, the inner diameter of the grounding shield 25 is restricted to a smaller one. The surface electric field of the center conductor 12 facing the electric field and grounding shield 25 is increased. In particular, there is a problem in that a very high electric field is generated at the upper end of the ground shield 25, degrading the insulation performance. In addition, the distance 11 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 the inner diameter of the insulator tube 11 and the grounding shield 25 become smaller.
There was a risk that the end face of the insulator tube 11 would be damaged due to the dimensional error between the two.

The present invention has been made in consideration of the above points, and its purpose is to simplify the installation of a grounding shield for improving potential distribution, to effectively utilize the space inside the insulator tube, and to reduce the size of the insulator tube and insulate it. Our objective is to provide gas bushings with improved performance.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the first invention of the present application provides a bushing in gas having an integral structure with the insulator pipe so that the ground shield is located inside the insulator pipe. It is characterized by
Further, a second invention of the present application is a gas bushing characterized in that a floating shield having a rounded end is embedded in an insulator tube.

(Function) Since each of the inventions of the present application is configured as described above, the electric field at the ground side end of the porcelain tube is relaxed.

(Example) (Example of the first invention) An example of the gas bushing of the first invention of the present application will be described below with reference to FIGS. 1 and 2.

Note that the same parts and parts having the same functions as those in FIG. 8 will be described with the same reference numerals.

The bushing 10 is constructed as follows. That is, the center conductor 12, which serves as a current-carrying conductor, is inserted into the hollow insulator tube 11, and the center conductor 12 is inserted inside the cover plate 14, which is attached to the upper mounting flange 13a, which is fixed to the upper part of the insulator tube 11 made of porcelain by cementing. One end of the conductor 12 is fixed.

In addition, when the lower part is attached to the lower part of the insulator pipe 11 by cementing 15, the flange 13b is attached to the cylindrical grounding fitting 17.
It is tightened and fixed via a bolt 18.

The cover plate 14 and the upper end surface of the insulator tube 11 are airtightly fixed via a backing (not shown), and a backing 19 is provided between the lower end surface of the insulator tube 11 and the grounding metal fitting 17.
It maintains airtightness through. Further, external shields 13 are provided on the upper and lower flanges 13a and 13b, respectively.
．． 13- is attached. (It is bypassed in Fig. 2.) Grounding shield 2 roughly formed into a cylindrical shape from metal.
0 is located inside the insulator tube 11 at a position coaxial with the outer periphery of the center conductor, and is configured to form an integral groove with the insulator tube 11. An insulating medium, for example an insulating gas 10a such as SF6 gas, is sealed inside the porcelain tube 11 and the grounding fitting 17.

Next, the state in which the grounding shield 20 is integrally constructed inside the insulator tube 11 in this manner will be described in detail. That is, ground shield 2
0 is formed with a rounded part 20a having a bending radius at the upper end to optimize the potential distribution, and the lower end is formed with the grounding fitting 1.
A smooth portion 20b is formed to be electrically connected to 7.

Therefore, the outer diameter to the outer end of the rounded portion 20a is φA
Also, if the inner diameter of the insulator 11 is φ0, then φA〉φ
A relationship of 0 holds true. The position of the grounding shield 20 within the insulator tube 11 is determined and integrally formed so that the potential distribution of the bushing 10 is optimized.

If the above-mentioned insulator tube 11 is now fastened to the grounding fitting 17 with the bolt 18, the lower smooth portion 20b of the grounding shield 20 will be electrically connected to the grounding fitting 17, and an optimum potential distribution will be obtained when voltage is applied.

As described above, according to this embodiment, the ground shield 20
By integrally forming the inside of the insulator tube 11, the grounding shield 20 can be constructed without being restricted by the inner diameter of the insulator tube. In other words, in the conventional ground shield mounting structure, when trying to downsize the bushing, φD〉φ
Since there was a relationship A, when φD was made smaller, the distance between the ground shield 20 and the center conductor could not be maintained, and the electric field of the center conductor 12 and the ground shield 20 increased, resulting in a decrease in insulation performance.

However, according to this embodiment, from the relationship φA>φD,
Grounding shield 20 without being restricted by the inner diameter of the insulator pipe φD
can be arranged, so even if the inside diameter φD of the insulator tube is made small, it is not necessary to increase the electric field of the center conductor 12 and the ground shield 20, and the insulation performance can be improved. Also, insulator 11
By integrally forming the grounding shield 20 and the grounding shield, there is no need to attach the grounding shield to the grounding shield mounting member, and the number of parts can be reduced.

Next, another embodiment of the first invention of the present application will be described with reference to FIG. The same parts or parts having the same functions as those in FIG. 2 are given the same reference numerals. That is, the ground shield 20a is made of conductive plastic, and the insulating tube 11 is made of insulating plastic, and both are integrally cast. According to Honomizo, it is possible to control the potential distribution by appropriately selecting the dielectric constant of the insulating plastic.
Insulation performance can be improved. Moreover, the weight of the entire bushing can also be reduced.

(Embodiment of the second invention) Hereinafter, an embodiment of the second invention of the present application will be described with reference to FIGS. 4 and 5. The same parts and parts having the same functions as those in FIGS. 1 to 3 are given the same reference numerals, and their explanations will be omitted.

Floating shield 21a and floating shield 2 formed of metal into a cylindrical shape with rounded ends
1b is constructed integrally with the insulator tube 11 at a position coaxial with the outer periphery of the center conductor inside the insulator tube 11.

In this way, when using an insulator tube in which multiple floating shields (for example, 21a, 21b) are embedded, the floating shields have a potential that is uniquely determined by the capacitance between each electrode. (See FIG. 6) not only makes it possible to control the potential relatively easily, but also makes effective use of the conventional gas space, making it possible to further downsize the insulator tube. Furthermore, since the number of parts can be eliminated, reliability is also increased. (
The lower mounting flange is used not only mechanically but also electrically. ) Furthermore, by increasing the number of floating shields, it is possible to reduce the number of external shields 13 on the ground side, making the structure simpler and effective in reducing costs.

In the above embodiment, a metal material (for example, aluminum) is used as the embedded floating shield, but it is also possible to use a conductive plastic material with high elasticity.

In addition, since the insulator tube is made of porcelain and it is necessary to embed a floating shield that is hardened at high temperatures and has good adhesiveness (no peeling), the floating shield is formed of a mesh-like metal object, a metal made by sintering porous metal plate powder, etc. It is also possible.

[Effects of the Invention] As explained above, according to the gas bushing of the present invention, it is possible to construct a grounding shield with good insulation performance, and the inner diameter of the insulator tube can be made small, resulting in a small size and light weight, and also with good insulation performance. It has the excellent effect of being easy to assemble.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of an embodiment of the first invention of the present application, Fig. 2 is a sectional view of the main part of the first, and Fig. 3 is a sectional view of the main part of another embodiment of the first invention of the present application. 4 is a sectional view of an embodiment of the second invention of the present application, FIG. 5 is a sectional view of the main part of FIG. 4, FIG. 6 is an equivalent circuit diagram of the embodiment of FIG. 4, FIG. 7 is a sectional view of the main parts of a conventional bushing. 10... Bushing 10a... Insulating gas 1
1... Insulator tube 12... Center conductor 13.
...External shields 13a, 13b...Upper and lower mounting flanges 14
... Lid plate 15 ... Cementing 16
...Grounding shield mounting member 17...Grounding fitting 18...Bolt 19.
...Backing 20...Grounding shield 20a
...Rounded part 20b...Smooth part (8733
) Agent Patent attorney Yoshiaki Inomata (one idiot) Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (7)

[Claims] (1) In a gas bushing in which a center conductor is inserted coaxially with an insulator tube filled with an insulating medium, the grounding shield on the earth side is located inside the insulator tube and has an integral structure with the insulator tube. A gas bushing characterized by: (2) The gas bushing according to claim 1, wherein the grounding shield is made of metal, and the porcelain tube is made of porcelain. (3) The gas bushing according to claim 1, wherein the grounding shield is made of metal, and the insulating tube is made of insulating plastic. (4) The gas bushing according to claim 1, wherein the grounding shield is made of conductive plastic, and the insulating tube is made of insulating plastic. (5) A gas bushing in which a center conductor is inserted coaxially with the insulator tube into an insulator tube filled with an insulating medium, and a floating shield is embedded in the insulator tube. . (6) The gas bushing according to claim 5, wherein the floating shield is made of conductive plastic. (7) The gas according to claim 5, wherein the floating shield embedded in the insulator tube is formed of a mesh-like metal object, a porous metal plate, or a metal obtained by sintering powder.・Bushing.