EP-4742473-A1 - INSULATION DEVICE

Abstract

An insulator (50) in which a high-voltage conductor (3) is supported by an insulating spacer (2) in a tank (10) in which an insulating medium is enclosed, includes an electric field relaxation shield (4) installed in a portion of the high-voltage conductor (3) adjacent to the insulating spacer (2), in which the electric field relaxation shield (4) includes a conductive portion (41) that has a cylindrical shape covering the high-voltage conductor (3) from a radially outer side and is electrically connected to the high-voltage conductor (3), and a semiconductive portion (42) that has a cylindrical shape covering the conductive portion (41) from a radially outer side.

Inventors

• MIYASHITA, MAKOTO

Assignees

• MITSUBISHI ELECTRIC CORPORATION

Dates

Publication Date

20260513

Application Date

20230707

Claims (6)

1. An insulator in which a high-voltage conductor is supported by an insulating spacer in a tank in which an insulating medium is enclosed, the insulator comprising: an electric field relaxation shield installed in a portion of the high-voltage conductor adjacent to the insulating spacer, wherein the electric field relaxation shield includes: a conductive portion that has a cylindrical shape covering the high-voltage conductor from a radially outer side and is electrically connected to the high-voltage conductor; and a semiconductive portion that has a cylindrical shape covering the conductive portion from a radially outer side.
2. The insulator according to claim 1, wherein the semiconductive portion includes a semiconductive material of which a resistance value is equal to or more than 10 6 Ω/cm 3 and less than 10 11 Ω/cm 3 .
3. The insulator according to claim 1, wherein the semiconductive portion includes a cylindrical insulation substance and a semiconductive coating layer provided on an outer peripheral surface of the cylindrical insulation substance, and the conductive portion is formed of a cylinder of a conductive material embedded in an inner peripheral surface of the cylindrical insulation substance.
4. The insulator according to claim 3, wherein the semiconductive coating layer includes a semiconductive material of which a resistance value is equal to or more than 10 6 Ω/cm 3 and less than 10 11 Ω/cm 3 .
5. The insulator according to claim 3, comprising a conductive material installed on a surface of the high-voltage conductor, wherein the conductive portion is electrically connected to the high-voltage conductor via the conductive material.
6. The insulator according to claim 3, wherein the cylindrical insulation substance has a porous structure including microvoids.

Description

Field The present disclosure relates to an insulator in which a high-voltage conductor is installed in a tank filled with an insulating medium. Background As an insulator that causes a current to flow in a high-voltage conductor installed in a tank filled with an insulating medium, an insulation opening/closing device including a breaker that can cut off the current flowing in the high-voltage conductor can be exemplified, in addition to an insulated bus that is installed between devices and electrically connects the devices with a high-voltage conductor. In the insulator, the tank is divided into a plurality of spaces by an insulating spacer. The high-voltage conductor is supported by the insulating spacer in each of the divided spaces. In the high-voltage conductor disposed in each of the divided spaces, an electric field on a surface having contact with the insulating medium is increased, in a portion close to the insulating spacer. Therefore, there is a possibility that discharge occurs due to a short circuit between the high-voltage conductor and the tank. Therefore, in the insulator, it has been necessary to increase a size of the tank and increase a distance between the high-voltage conductor and the tank, in order to prevent the short circuit. Patent Literature 1 discloses an insulator in which an electric field relaxation shield formed of an insulation substance is installed on a surface of a portion close to an insulating spacer, in a high-voltage conductor. In the insulator disclosed in Patent Literature 1, by providing the electric field relaxation shield on the surface of the portion close to the insulating spacer, in the high-voltage conductor, a strength of an electric field of the electric field relaxation shield surface is caused to be lower than a strength of an electric field of a surface of a high-voltage conductor in a shieldless insulator. As a result, since the discharge is less likely to occur between the electric field relaxation shield and the tank in the insulator disclosed in Patent Literature 1, it is possible to reduce a size of the tank and miniaturize the device. Citation List Patent Literature Patent Literature 1: Japanese Patent Application Laid-open No. 2013-172561 Summary of Invention Problem to be solved by the Invention In a case where an electric field relaxation shield is formed of an insulation substance on a surface of a high-voltage conductor, there is a possibility that voids are mixed into the insulation substance, cracks are generated in the insulation substance, and peeling occurs in a contact portion between the high-voltage conductor and the insulation substance so that an air gap is generated in the insulation substance forming the electric field relaxation shield. When an AC voltage is applied to the insulation substance including the air gap such as the void, the crack, or the peeling, partial discharge occurs in the air gap. The partial discharge occurred in the air gap in the insulation substance eventually becomes electric tree discharge, causes the discharge to progress in the insulation substance, and gradually lowers an insulation performance of the insulation substance. Since the insulation performance of the insulation substance has a non-self-restoring property that does not perform self-restoration, the insulation performance finally causes electrical insulation breakdown. Therefore, the air gap in the insulation substance becomes a defect for lowering the insulation performance. In the insulator disclosed in Patent Literature 1, the electric field relaxation shield is formed of the insulation substance. Therefore, in a case where there is the defect in the insulation substance, if the insulation performance of the electric field relaxation shield is lowered by the application of the AC voltage and the insulation breakdown occurs, a function of the electric field relaxation effect by the electric field relaxation shield is lost. If the function of the electric field relaxation effect is lost due to the insulation breakdown, not only an electric field relaxation shield effect for an AC voltage, but also an electric field relaxation shield effect sometimes impaired when a lightning impulse voltage is applied. The present disclosure has been made in view of the above, and an object of the present disclosure is to obtain an insulator that suppresses a relaxation function of an electric field relaxation shield from being impaired by insulation breakdown. Means to Solve the Problem To solve the above problems and achieve the object, an insulator according to the present disclosure is an insulator in which a high-voltage conductor is supported by an insulating spacer in a tank in which an insulating medium is enclosed. The insulator includes: an electric field relaxation shield installed in a portion of the high-voltage conductor adjacent to the insulating spacer. The electric field relaxation shield includes: a conductive portion that has a cylindrical