JP2020092110A - Electric field relaxation shield, gas-insulated bushing, and manufacturing method of electric field relaxation shield - Google Patents

Abstract

To obtain an electric field relaxation shield capable of ensuring insulation reliability and downsizing.SOLUTION: An electric field relaxation shield 10 is provided on a gas-insulated bushing 1 having a porcelain bushing 4 in which an insulating gas is sealed and a central conductor 3 which is a conductor arranged inside the porcelain bushing 4. The electric field relaxation shield 10 includes an insulator 11 having a tubular portion 13 having a tubular shape, and a ring portion 14 having a shape opened from an end of the tubular portion 13 to a side opposite to a central axis side of the tubular portion 13, and a conductive layer 12 that covers the entire outer peripheral surface 16 of the tubular portion 13 opposite to the central axis side and the portion of the ring portion 14 connected to the outer peripheral surface 16.SELECTED DRAWING: Figure 1

Description

The present invention relates to an electric field relaxation shield that relaxes the concentration of an electric field in a gas insulating bushing, a gas insulating bushing, and a method for manufacturing the electric field relaxation shield.

A gas-insulated bushing used in a place where a conductor is drawn out from a device such as a transformer or a circuit breaker may be provided with an electric field relaxation shield for relaxing concentration of an electric field inside a porcelain tube sealed with an insulating gas.

Patent Document 1 discloses a gas-insulated bushing to which a ground shield that is an electric field relaxation shield is attached. The electric field relaxation shield disclosed in Patent Document 1 is attached to the tank flange to which the porcelain insulator is fixed, and controls the potential distribution inside the porcelain insulator.

JP-A-9-27225

The electric field relaxation shield is assumed to have the same characteristics as a metal shield provided with an insulating coating by forming a conductive layer made of a metal material on an insulator. In order to secure insulation reliability, it is necessary to secure a distance between the conductive layer of the electric field relaxation shield and the central conductor in the porcelain tube. Therefore, conventionally, there has been a problem that it is difficult to downsize the electric field relaxation shield in order to secure the distance between the conductive layer and the central conductor.

The present invention has been made in view of the above, and an object of the present invention is to obtain an electric field relaxation shield that can secure insulation reliability and can be downsized.

In order to solve the above-mentioned problems and to achieve the object, the electric field relaxation shield according to the present invention is provided in a gas-insulated bushing having a porcelain bushing in which an insulating gas is sealed and a conductor arranged inside the porcelain bushing. The electric field relaxation shield according to the present invention includes an insulator having a tubular portion having a tubular shape and a ring portion having a shape opened from an end of the tubular portion to a side opposite to a central axis side of the tubular portion; And a conductive layer that covers the entire outer peripheral surface, which is the surface opposite to the central axis side, and the portion of the ring portion that is connected to the outer peripheral surface.

According to the present invention, it is possible to secure insulation reliability and reduce the size.

Sectional drawing which shows the gas insulation bushing which has an electric field relaxation shield concerning Embodiment 1 of this invention. The 1st figure explaining the manufacturing method of the electric field relaxation shield concerning Embodiment 1. The 2nd figure explaining the manufacturing method of the electric field relaxation shield concerning Embodiment 1.

Hereinafter, a method for manufacturing an electric field relaxation shield, a gas insulating bushing, and an electric field relaxation shield according to an embodiment of the present invention will be described in detail with reference to the drawings. The present invention is not limited to this embodiment.

Embodiment 1.
FIG. 1 is a sectional view showing a gas insulation bushing 1 having an electric field relaxation shield 10 according to a first embodiment of the present invention. The gas-insulated bushing 1 is used at a location where a conductor is drawn from a tank 2 that constitutes a device. The tank 2 is a metal cylindrical container.

The gas insulating bushing 1 has a porcelain bushing 4 in which an insulating gas is sealed, and a central conductor 3 arranged inside the porcelain bushing 4. The central conductor 3 is a rod-shaped conductor extending in the direction of the central axis of the porcelain bushing 4. The insulating gas is an insulating gas containing sulfur hexafluoride gas or sulfur hexafluoride gas. The cross section shown in FIG. 1 is a cross section including the central axis of the porcelain insulator tube 4. The central conductor 3 is coaxial with the porcelain bushing 4 and is inserted into the porcelain bushing 4. In the following description, the central axis side may be referred to as the inner peripheral side, and the side opposite to the central axis side may be referred to as the outer peripheral side.

The porcelain insulator 4 has a tubular body 8 formed using fiber reinforced plastics (FRP), and a synthetic resin outer covering portion 7 that covers the outer peripheral side of the tubular body 8. A protrusion for ensuring a creeping distance is formed on the outer peripheral surface of the outer cover portion 7. An end of the porcelain insulator 4 on the tank 2 side is fixed to a tank flange 9 provided on the tank 2. A ground flange 5 connected to a reference potential point is fixed to the tank flange 9.

The electric field relaxation shield 10 is provided inside the insulator tube 4. The electric field relaxation shield 10 has an insulator 11 made of an insulating material and a conductive layer 12 made of a metal material. The insulating material is a material that is also a thermoplastic material, such as polyvinyl chloride or polypropylene. The metallic material is aluminum, zinc, or an alloy of aluminum and zinc. The electric field relaxation shield 10 is arranged coaxially with the porcelain insulator 4. The center conductor 3 penetrates the inside of the electric field relaxation shield 10. The electric field relaxation shield 10 is arranged apart from the central conductor 3.

The insulator 11 has a tubular portion 13 having a tubular shape, and a ring portion 14 having a shape opened from one end of the tubular portion 13 to the outer peripheral side. The insulator 11 is arranged such that the central axis of the tubular portion 13 is aligned with the central axis of the porcelain insulator 4. The ring portion 14 has a folded-back shape that is bent from one end of the tubular portion 13 toward the outer peripheral side and further bent toward the flange portion 15. The electric field relaxation shield 10 also has a flange portion 15 provided at the other end of the tubular portion 13. The electric field mitigation shield 10 is provided with the ring portion 14 that is open to the outer peripheral side, so that electric field concentration at the end of the tubular portion 13 can be mitigated. The shape of the ring portion 14 is not limited to the shape shown in FIG. 1 and may be appropriately modified.

The conductive layer 12 covers the entire outer peripheral surface 16 of the cylindrical portion 13 that is a cylindrical surface facing the outer peripheral side, and the portion of the ring portion 14 that is connected to the outer peripheral surface 16. In the ring portion 14, the conductive layer 12 is provided on the inner surface of the folded portion. The conductive layer 12 is also provided on the surface of the flange portion 15 opposite to the ground flange 5 side. The conductive layer 12 has a thickness of 50 μm to 100 μm. The conductive layer 12 is formed with a uniform thickness on the outer peripheral surface 16, the portion of the ring portion 14 connected to the outer peripheral surface 16 and the surface of the flange portion 15 opposite to the ground flange 5 side. . The conductive layer 12 is not provided on the inner peripheral surface 17 of the insulator 11 which is the inner surface facing the inner peripheral side. Therefore, the insulator 11 faces the central conductor 3.

The flange portion 15, the ground flange 5, and the tank flange 9 are fastened together by the fastening component 6. As a result, the electric field relaxation shield 10 is fixed to the tank flange 9 via the ground flange 5. The electric field relaxation shield 10 is grounded by contact with the ground flange 5. Bolts and nuts are used for the fastening component 6. The electric field relaxation shield 10 may be fixed by means other than the fastening component 6.

Since the conductive layer 12 is not provided on the inner peripheral surface 17 of the electric field relaxation shield 10, the insulator 11 made of an insulating material is arranged on the inner peripheral side where a higher electric field is obtained. The electric field relaxation shield 10 can increase the electric field relaxation efficiency by arranging the insulator 11 on the inner peripheral side where a higher electric field is provided.

By providing conductive layer 12 on outer peripheral surface 16 of electric field relaxation shield 10, conductive layer 12 is arranged at a position farther from central conductor 3 than when conductive layer 12 is provided on inner peripheral surface 17. The electric field relaxation shield 10 can secure the distance between the conductive layer 12 and the center conductor 3. In the electric field relaxation shield 10, the conductive layer 12 is arranged so that the distance between the conductive layer 12 and the central conductor 3 can be secured, so that the diameter of the tubular portion 13 can be further reduced while ensuring insulation reliability. As a result, the electric field relaxation shield 10 can secure insulation reliability and be miniaturized.

By reducing the size of the electric field relaxation shield 10, the weight of the electric field relaxation shield 10 can be reduced. Since the electric field relaxation shield 10 is lightweight, the work of attaching the electric field relaxation shield 10 becomes easier. Further, since the electric field relaxation shield 10 can be downsized, the gas insulating bushing 1 can also be downsized.

Next, a method for manufacturing the electric field relaxation shield 10 will be described. FIG. 2 is a first diagram illustrating the method of manufacturing the electric field relaxation shield 10 according to the first embodiment. FIG. 2 shows a step of forming the insulator 11 by molding an insulating material. In the first embodiment, the insulator 11 is formed by injection molding using an insulating and thermoplastic material. The insulator 11 may be formed by a method other than injection molding.

FIG. 3 is a second diagram illustrating the method of manufacturing the electric field relaxation shield 10 according to the first embodiment. FIG. 3 shows a step of forming the conductive layer 12 by spraying a metal material on the entire outer peripheral surface 16 of the cylindrical portion 13 and the portion of the ring portion 14 connected to the outer peripheral surface 16. The conductive layer 12 is also formed on the surface of the flange portion 15 opposite to the ground flange 5 side by thermal spraying of a metal material. According to the method of manufacturing the electric field relaxation shield 10 according to the first embodiment, as compared with the case of bending a plate of a metal material or welding a metal material processed into a ring shape to a metal material processed into a tubular shape. A shape that can satisfy the electric field relaxation performance required for the electric field relaxation shield 10 can be easily obtained.

In this step, the metal particles 21 that are the melted metal material are jetted from the nozzle 20 to the insulator 11 that is the base material, so that the conductive layer 12 that is a film of the metal particles 21 is formed on the surface of the insulator 11. It The thermal spraying is suitable for forming a film of a metal material in a wide range as compared with the case of vacuum deposition which is one of other manufacturing methods used for forming a metal film. In the first embodiment, conductive layer 12 having a uniform thickness can be easily formed on the entire outer peripheral surface 16 and the portion of ring portion 14 connected to outer peripheral surface 16 by thermal spraying. Further, the thermal spraying makes it possible to easily obtain the conductive layer 12 having the thickness required for shielding the electric field.

In the case of vacuum deposition, the larger the substrate, the larger the equipment required, whereas in the case of thermal spraying, there is the advantage that the equipment of the thermal spraying machine is simple regardless of the dimensions of the substrate. Further, in the case of vapor deposition, the entire base material is formed into a film, while in the case of thermal spraying, there is an advantage that a desired portion of the base material can be formed into a film. Therefore, in the first embodiment, conductive layer 12 can be easily formed by thermal spraying.

In the first embodiment, the conductive layer 12 is formed by the flame-type flame spraying, which is one of the spraying methods. In the flame-spraying type flame spraying, it is possible to keep the temperature of the base material at a low temperature as compared with other spraying methods. Therefore, the use of the hot wire flame spraying can reduce the influence of heat on the insulator 11 made of a thermoplastic material, and the conductive layer 12 can be formed without degrading the insulator 11.

The thermal spraying can form the conductive layer 12 having high adhesion to the insulator 11 as compared with the case of applying a metal material which is one of other manufacturing methods used for forming a metal film. Further, in the case of thermal spraying, since the surface of the metal particles 21 and the metal particles 21 become oxides or carbides to form a metal material, there is an advantage that abrasion resistance can be easily obtained. Therefore, in the first embodiment, the conductive layer 12 having high adhesion to the insulator 11 can be formed by thermal spraying.

The electric field relaxation shield 10 can suppress peeling of the conductive layer 12 from the insulator 11 by increasing the adhesion of the conductive layer 12 to the insulator 11. The electric field relaxation shield 10 can suppress the occurrence of a situation such as partial discharge due to adhesion of debris separated from the conductive layer 12 and further dielectric breakdown due to partial discharge.

Since the electric field relaxation shield 10 uses a thermoplastic material for the insulator 11, the insulator 11 having an arbitrary shape can be easily formed. Moreover, since the insulator 11 can be made lightweight by using the thermoplastic material, the weight of the electric field relaxation shield 10 can be reduced. The insulator 11 does not have to be made of a thermoplastic material, and may be made of at least an insulating material.

According to the first embodiment, the electric field relaxation shield 10 includes the conductive layer 12 that covers the entire outer peripheral surface 16 of the insulator 11 and the portion of the ring portion 14 that is connected to the outer peripheral surface 16. It is possible to secure the distance between 12 and the central conductor 3. In the electric field relaxation shield 10, the conductive layer 12 is arranged so that the distance between the conductive layer 12 and the central conductor 3 can be secured, so that the diameter of the tubular portion 13 can be further reduced while ensuring insulation reliability. As described above, the electric field mitigation shield 10 has an effect of ensuring insulation reliability and downsizing.

The configurations described in the above embodiments are examples of the content of the present invention, and can be combined with another known technique, and the configurations of the configurations are not departing from the scope of the present invention. It is also possible to omit or change parts.

1 Gas Insulation Bushing, 2 Tank, 3 Center Conductor, 4 Insulator Tube, 5 Grounding Flange, 6 Fastening Parts, 7 Outer Cover, 8 Cylindrical Body, 9 Tank Flange, 10 Electric Field Mitigation Shield, 11 Insulator, 12 Conductive Layer, 13 Cylindrical part, 14 ring part, 15 flange part, 16 outer peripheral surface, 17 inner peripheral surface, 20 nozzle, 21 metal particles.

Claims (4)

An electric field mitigation shield provided on a gas insulating bushing having a porcelain bushing in which an insulating gas is sealed and a conductor arranged inside the porcelain bushing,
An insulator having a tubular portion having a tubular shape and a ring portion having a shape opened from an end of the tubular portion to a side opposite to a side of a central axis of the tubular portion,
A conductive layer that covers the entire outer peripheral surface that is the surface on the side opposite to the central axis of the tubular portion and the portion of the ring portion that is connected to the outer peripheral surface,
An electric field mitigation shield having: The electric field relaxation shield according to claim 1, wherein the insulator is made of a thermoplastic material. Insulator tube filled with insulating gas,
A conductor disposed inside the porcelain bushing,
An electric field relaxation shield disposed inside the porcelain tube,
The electric field relaxation shield is
An insulator having a tubular portion having a tubular shape and a ring portion having a shape opened from an end of the tubular portion to a side opposite to a side of a central axis of the tubular portion,
A conductive layer that covers the entire outer peripheral surface that is the surface on the side opposite to the central axis of the tubular portion and the portion of the ring portion that is connected to the outer peripheral surface,
A gas-insulated bushing having: A method of manufacturing an electric field relaxation shield for manufacturing an electric field relaxation shield provided in a gas insulating bushing having a porcelain insulator tube in which an insulating gas is sealed and a conductor arranged inside the porcelain insulator tube,
By molding the insulating material, an insulator having a tubular portion having a tubular shape and a ring portion having a shape opened from an end portion of the tubular portion to a side opposite to a central axis side of the tubular portion is formed. Process,
A step of forming a conductive layer by spraying a metal material on the entire outer peripheral surface of the tubular portion opposite to the central axis side and the portion of the ring portion connected to the outer peripheral surface; ,
A method for manufacturing an electric field relaxation shield, comprising:

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