JPH0747928Y2 - Electric field relaxation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial field of use) The present invention relates to an electric field mitigating device used in an insulating gas, and more particularly to a shield for a gas-insulated cubicle storage device for enclosing the insulating gas. It concerns the structure of the ring.

(Prior Art) In recent years, in order to reduce the installation space and save labor for maintenance and inspection, a plurality of electric devices are housed inside a closed container, and these are connected by a conductor, and SF6 gas such as SF ₆ gas is used. Gas-insulated cubicles filled with an insulating medium (hereinafter referred to as SF ₆ gas) are widely used in power distribution equipment.

FIG. 3 shows an example of the structure of this gas-insulated cubicle. In the figure, SF ₆ gas is enclosed in the closed container 1 at almost atmospheric pressure, and the circuit breaker 2, main circuit conductor 3, disconnector 4, busbar
5, an insulator 7 for supporting and fixing the cable head 6 and the bus bar 5 is housed, and required wiring is carried out.

By the way, in such a gas-insulated cubicle, since each electric device is rationally arranged, the main circuit has sharp corners at various points in its structure. Therefore, a round metal is provided to alleviate the electric field at this portion. An example of this is the shield ring 8 attached to the connection between the cable head 6 and the main circuit conductor 3.

FIG. 4 shows an enlarged upper part of the cable head 6 for one phase. In the figure, the shield ring 8 is an insulating layer 9 constituting the cable head 6, an electrode 10 fixed to the insulating layer 9 by integral casting or the like, and an electric field relaxation at an acute angle portion at a connection portion with the main circuit conductor 3. It is provided for the purpose of

The shield ring 8 is formed by bending a metal plate, and has a cylindrical portion 8a, curved portions 8b and 8b in which both ends of the cylindrical portion 8a are curved inward with a radius of curvature R, and a cylindrical portion. The support plate 11 is fixed to the inside of 8a by welding or the like, and is fixed to the main circuit conductor 3 by a bolt 12.

By attaching the shield ring 8, the electric field is relaxed with respect to the connecting portion of the main circuit conductor 3, the creeping direction of the insulating layer 9, the container wall 13 of the closed container 1, the reinforcing member 14 attached to the container wall 13 and the like. Can be achieved. Such electric field relaxation is also disclosed in JP-A-62-23312 and JP-A-62-23308 as means for suppressing the maximum electric field strength and reducing the insulation distance.

In this way, the shield ring 8 formed so as to have a rounded outer periphery covers the internal acute angle portion. This is a means for suppressing the maximum internal electric field strength by the shield ring 8 because the SF ₆ gas exhibits a strong electric negativeness, and its dielectric breakdown characteristics greatly depend on the maximum electric field strength. Has a rounded shape to suppress the maximum electric field strength.

(Problems to be solved by the invention) In order to suppress the maximum electric field strength, if the radius of curvature of the shield ring is increased, the effect is increased accordingly.

However, when the radius of curvature becomes large, the manufacturing time of the shield ring 8 becomes long, the manufacturing cost increases, the weight also increases, and a large mechanical stress acts on the insulating support that supports the main circuit conductor.

Further, in the gas-insulated cubicle, as described above, various electric devices are collectively housed in the closed container 1 and rationally arranged. However, when the shield ring 8 becomes large, the shield ring 8 causes the electric devices Placement is restricted. For example, the cable head 6 has a three-phase closed container 1
Since they are arranged in a line in the width direction, the shield rings 8 are necessarily arranged in a line in the same direction. Therefore, between the shield rings 8, that is, between the phases and between the shield rings 8
The insulation distance between the ground and the ground, especially the ground with the reinforcing member 14 of the container wall 13 is the minimum distance due to the electric field relaxation by the shield ring 8, but the shield ring 8 is large, and as a result, the overall shape of the cable head 6 is reduced. Will be large and will limit the miniaturization of the gas-insulated cubicle.

Further, when the shield ring 8 is large, there is little free space when connecting the main circuit conductor 3 and wiring work of the electric equipment to be housed, which deteriorates workability. Therefore, an object of the present invention is to provide an electric field mitigating device that is small and lightweight, reduces the overall shape of the applied electric equipment, and improves workability.

[Structure of the Invention] (Means for Solving the Problems) The present invention relates to an electric field relaxation device fixed to a main circuit conductor supported through an insulator in an insulating gas, and is a cylinder formed of a metal material. Bend the end of the insulator on the insulator side outward,
The end portion on the main circuit conductor side is curved inward with substantially the same radius of curvature.

(Operation) Since each end of the cylindrical portion, that is, both the end on the main circuit conductor side and the end on the insulator side are curved with the same radius of curvature as before, the electric field strength of each part hardly changes, The side curved inward can be miniaturized by the radius of curvature.

Embodiment An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, the shield link 20 is a cable head 6
Cylindrical part 20 having an inner diameter slightly larger than the outer diameter of the insulating layer 9 of
a and a curved portion that is curved outward at the bottom of the cylindrical portion 20a
20b and the curved portion 20 that is curved inward at the upper part of the cylindrical portion 20a.
It consists of c. Here, the lower curved portion 20b and the upper curved portion 20c have the same radius of curvature R as the conventional shield ring 8. Further, since the bending portion 20b is bent outward,
The curved portion 20c has an arc portion of approximately 90 ° because it has an arc portion of 80 ° or more, and the curved portion 20c bends inward.
Bend further inward with a smaller radius of curvature. In addition,
The cylindrical portion 20a is provided with a mounting hole (not shown) at an intermediate portion thereof.

When the shield ring 20 configured as described above is attached to the upper portion of the cable head 6, since there is a gap of several mm between the shield ring 20 and the insulating layer 9, the bolt 21 is inserted into the hole provided in the cylindrical portion 20a and the spacer is inserted. It is fixed to the electrode 10 via 22. Here, the bolt 21 is a round screw so that there is no sharp corner.

The shield ring 20 having the above structure has the same radius of curvature R at the upper and lower ends of the shield ring 20 as that of the conventional shield ring, so that the electric field strength does not increase. This is because the position of the shield ring 20 showing the maximum electric field strength exists near the point facing the closed container wall 13 rather than the point facing the insulating layer 9 on the arc of the curved portion 20b in the lower part, and the upper part is curved. Department
Since it exists on an arc with a radius of curvature R of 20c, the radius of curvature R
Does not change and the insulation distance is constant, the electric field strength does not change. Rather, in the upper part, the insulation distance between the container wall 13 and the reinforcing member 15 is widened, so that the electric field strength can be suppressed. Further, the head of the bolt 21 protrudes from the surface of the shield ring 20, but since it has a roundness and is not large in size, it does not exceed the electric field strength of the upper or lower curved portion.

Therefore, according to the above-described embodiment, since the outer shape of the shield ring is downsized, the mechanical stress acting on the supporting portion is reduced and the overall shape of the applied electric device can be downsized. In addition, the electric equipment housed in the gas-insulated cubicle can be arranged and connected more rationally than in the past, and workability and maintainability can be improved.

Although the shield ring is integrated in the above description, it may be a divided structure to facilitate the work such as assembly and connection.

FIG. 2 shows a state in which a shield ring having a split structure is attached to the cable head for one phase. In the figure, the shield ring 25 is composed of an upper shield ring 26 and a lower shield ring 27. Here, the upper shield ring 26 has an inner diameter slightly larger than the outer diameter of the insulating layer 9 of the cable head 6, and a cylindrical portion 26a provided with a mounting hole (not shown) below, and the cylindrical portion 26a. It is composed of a curved portion 26b that is curved inward at the top, and this curved portion 26b is almost
The 90 ° arc portion and the end portion are curved inward with a small radius of curvature. Further, the lower shield ring 27 has the same inner diameter as the cylindrical portion 26a, a cylindrical portion 27a provided with a mounting hole (not shown) on the upper side, and a curve curved outward at the lower portion of the cylindrical portion 27a. The curved portion 27b is formed to have a circular arc portion of 180 ° or more.

When the shield ring 25 configured as described above is attached to the upper portion of the cable head 6, the upper shield ring 26 and the lower shield ring 27 are separated from each other and the main circuit conductor 3 is connected to the electrode 10. Lower shield ring 27
Has a gap with the insulating layer 9, so the bolt 21a
Is inserted into a hole provided in the cylindrical portion 27a and fixed to the electrode 10 via the spacer 22a. Since the upper shield ring 26 has a gap with the main circuit conductor 3, the bolt 21b is inserted into the cylindrical portion 27a.
And is fixed to the main circuit conductor 3 via the spacer 22b. At this time, the lower end of the upper shield ring 26 and the upper end of the lower shield ring 27 are brought into contact with each other. In addition,
The bolts 21a and 21b are round screws like the bolt 21 so that there are no sharp corners.

In this embodiment, since the upper shield ring 26 and the lower shield ring 27 are fixed, a contact surface is formed. However, the electric field strength of the surface of the cylindrical part by this contact surface is several 10% lower than the surface of the upper or lower curved part, and even if there is a gap due to slight contact deviation, It never grows.

Therefore, also in the case of this embodiment, the outer shape of the shield ring can be made smaller, and the same effect as that of the above-mentioned embodiment can be obtained. Further, since the parts are divided, the outer shape of each part becomes smaller and the handling becomes easier, and it is possible to prevent the occurrence of scratches and unevenness during the mounting work and to prevent the increase of the electric field strength.

[Advantages of the Invention] Since the present invention is configured as described above, the outer shape is made small, so that the mechanical stress acting on the supporting portion is reduced and the overall shape of the applied electric device can be made small. . Therefore, when a plurality of electric devices are housed in an airtight container, a more rational arrangement can be made, not only downsizing can be realized, but also connection can be facilitated and workability is improved.

[Brief description of drawings]

FIG. 1 is a side view showing a state in which an embodiment of the present invention is cut and fixed to an upper part of a cable head, and FIG. 2 shows a state in which another embodiment of the present invention is cut and fixed to an upper part of a cable head. A side view, FIG. 3 is a side view showing a gas-insulated cubicle related to the present invention, and FIG. 4 is a side view showing a state in which a conventional electric field relaxation device is cut and fixed to an upper portion of a cable head. 3 ... Main circuit conductor 6 ... Cable head 9 ... Insulating layer 20a ... Cylindrical part 20b, 20c ... Curved part

Claims (1)

[Scope of utility model registration request] 1. An electric field relaxation device fixed to a main circuit conductor supported through an insulator in an insulating gas atmosphere,
An electric field mitigating device, characterized in that an end of the cylindrical portion formed of a metal material on the side of the insulator is curved outward, and an end on the side of the main circuit conductor is curved inward with substantially the same radius of curvature. .