JPH0520972A - Switchgear - Google Patents

Abstract

PURPOSE:To provide a switchgear capable of preventing the dielectric breakdown of an insulation cylinder creeping surface against overvoltage occurring with the open and close operation of a switchgear, and ensuring a stable surge absorption effect. CONSTITUTION:A shield comprising an insulation cylinder 11 is provided around a stationary electrode 2. In addition, firing resistant metal 5 is fitted to the end of the cylinder 11. Also, a resistance wire 10 is buried inside the cylinder 11 and wrinkles are formed on the surface of the cylinder 11. According to this construction, the dielectric breakdown of the creeping surface of the cylinder 11 can be prevented with the wrinkles.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switchgear with resistance for suppressing an overvoltage generated when a contact part is opened and closed.

[0002]

2. Description of the Related Art In a substation or a switchyard, a gas-insulated switchgear adopting a gas-insulated system has been widely put into practical use in order to protect equipment in case of system switching or line failure. A gas-insulated switchgear is a closed container that contains disconnectors, circuit breakers, grounding devices, instrument transformers, lightning arresters, etc., which are required for opening and closing operations. SF6 gas and other insulating gas are used in the surrounding space. Is sealed under pressure. These devices are
Each is supported and fixed by an insulating spacer and connected to each other by a high voltage conductor.

The gas-insulated switchgear is easy to open and close with high voltage and high power, has high reliability, and is highly safe.
Since it has many excellent features such as compactness and excellent harmony with the environment, it is widely used today as the central equipment of power transmission and transformation equipment.

When switching the system, the circuit breaker or disconnector installed in the gas insulated switchgear is used to disconnect or connect the systems. In addition, the grounding device is used to ground the charging part when inspecting equipment. During such switching operation of the switchgear, an overvoltage is generated which is determined by the circuit configuration and the characteristics of the switchgear.
In particular, an overvoltage called a disconnector surge is generated during switching operation of the disconnector. This overvoltage has a high surge level, and the rise time of the surge voltage is extremely fast from several nanoseconds to several tens of nanoseconds. It is known that there is a possibility of threatening the insulation of the component equipment and a possibility of causing damage to peripheral equipment as well, and suppression thereof is desired.

Hereinafter, this point will be described by taking an example of a disconnector as the switchgear.

In order to suppress the above-mentioned overvoltage, for example, a disconnecting switch with resistance is proposed in Japanese Utility Model Laid-Open No. 53-53332. This is shown in FIG. In FIG. 2, the fixed electrode 2 and the movable electrode 3 are arranged to face each other inside a sealed container 1 to form a main contact. In addition, the fixed electrode 2
A fixed electrode side shield 4 is provided around the. The fixed electrode side shield 4 is composed of a resistor, and the tip portion thereof is rounded in an arc shape in cross section, and
The arc-resistant metal 5 is attached to the tip. Furthermore,
The fixed electrode 2 is connected to another device via a conductor 7, and the movable electrode 3 is connected to another device via a current collector 8.

In such a disconnecting switch, when the disconnecting switch is closed, the movable electrode 3 exists at the position shown by the dotted line in the figure, and electricity is supplied. On the other hand, when the electrode is opened, the movable electrode 3 moves to the right side of the drawing, and an arc is generated at the tips of the fixed electrode 2 and the movable electrode 3 in the initial stage. Then, the movable electrode 3 further moves to the right side, so that the arc-resistant metal 5 at the tip of the fixed electrode side shield 4 and the arc 9 are generated at the tip of the movable electrode 3.

Since the current at this time flows through the resistor inside the fixed electrode side shield, surge energy is absorbed by the resistor and the occurrence of overvoltage is suppressed. Further, at the time of the closing operation, first, the movable electrode 3 and the arc-proof metal 5 are
After the arc is generated between the fixed electrode 2 and the movable electrode 3
Therefore, energy is absorbed by the resistor at the initial stage of application when there is a risk of overvoltage, and generation of overvoltage is suppressed. Then, energization is performed in a state where the fixed electrode 2 and the movable electrode 3 are completely in contact with each other.

[0009]

However, the above-mentioned disconnector has the following problems. That is, in order to suppress the generated surge level, several hundreds
Resistors with a resistance of ohms to several kilo-ohms are used. However, when a surge occurs, an overvoltage determined by the circuit constant is applied to the resistor.If the voltage level at this time exceeds the dielectric strength of the resistor, dielectric breakdown occurs inside the resistor or inside the insulator. Occurs. In such a case, the original surge suppression effect cannot be expected.
Although breakdown may occur inside the insulator as well, normally, the breakdown voltage inside a solid is higher than the creepage breakdown voltage in gas, so it was necessary to improve the creepage breakdown characteristics.

The present invention has been proposed in order to solve the above-mentioned drawbacks, and provides a switching device with resistance which always has a constant surge suppressing effect by improving the creepage destruction characteristic of the shield with resistance. The purpose is to

[0011]

In order to solve the above-mentioned problems, the present invention provides a movable electrode and a fixed electrode, which are concentric and separable, facing each other on a concentric shaft, and a shield is provided around the fixed electrode. In a switchgear in which a resistance wire or resistor is provided inside the shield to form a shield with resistance, and the periphery of the resistance wire or resistor is supported and fixed by an insulating material such as epoxy resin, insulation of the shield with resistance It is characterized in that a fold is provided on the surface of the material.

[0012]

That is, according to the switchgear with resistance of the present invention, the creases on the surface of the insulating material can improve the creeping dielectric strength of the shield with resistance, and the switchgear with resistance which always has a constant surge suppression effect. Equipment can be provided.

[0013]

【Example】

 (1) Representative Examples Hereinafter, the present invention will be described with reference to the drawings.

An embodiment of the shield with resistance according to the present invention is shown in FIG. The same parts as those in FIGS. 2 and 3 are designated by the same reference numerals and the description thereof will be omitted.

In FIG. 1, 2 is a fixed electrode, 5 is an arc-proof metal, and 7 is a conductor. In this embodiment, the resistance wire 10
Is an insulating cylinder 1 made of an insulating material such as epoxy resin
1 is embedded in the insulating cylinder 11, and pleats are formed on the inner and outer peripheral surfaces of the insulating cylinder 11. The shape of the pleats is not particularly limited, but in order to increase the creepage distance, for example, as shown in FIG. 1, the pleats have a certain thickness in a direction substantially orthogonal to the insulating cylinder 11 and have a tip portion. A shape having a circular arc cross section is preferable.

According to this embodiment, even if the overvoltage generated by the opening / closing operation of the disconnecting switch is applied to the shield with resistance, the crease attached to the creeping surface of the insulating cylinder improves the dielectric strength of the creeping surface. As a result, it is possible to provide a switchgear with resistance that can prevent creeping damage and always have a constant surge suppression effect.

(2) Other Embodiments The above description has been made in the case of a disconnector as the switchgear, but the same applies to switchgear other than the switchgear, such as a grounding device. Even in this case, a certain surge suppression effect can be expected by mounting the shield with resistance according to the present invention on the fixed electrode side. Particularly, in a gas-insulated switchgear using SF6 gas as an insulating medium, an extremely steep surge occurs. Therefore, it is considered to be extremely effective to employ the shield with resistance according to the present invention.

A material such as a nichrome wire may be used as the resistance wire, but any material having resistance for absorbing surge may be used. For example, a ceramic resistor, a carbon resistor or a metal film resistor may be used. The effect of can be expected. Also in this case, the creepage breakdown characteristic can be improved by attaching the pleats to the resistance surface or the surface of the insulating material covering these resistances. Further, if the resistance wire or the resistance body is formed in a cylindrical shape, not only the structure becomes simple, but also the casting work of the insulating cylinder 11 becomes easy.

Also, in the illustrated embodiment, the folds are resistance wires 10
Although it is formed on the outer peripheral surface and the inner peripheral surface of the insulating cylinder that accommodates the above, it may be either one. Further, the pleats may be provided with a slight inclination to make the casting work easier.

[0020]

As described above, according to the present invention, by providing the folds on the surface of the insulating cylinder of the shield with resistance, it is possible to prevent the dielectric breakdown of the surface of the insulating cylinder against the overvoltage generated by the opening / closing operation. This makes it possible to provide a switchgear that can expect a stable surge absorption effect.

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional view showing an embodiment of a shield portion with a resistance in a switchgear according to the present invention.

FIG. 2 is a sectional view showing an electrode portion of a disconnector which is an example of a conventional switchgear.

FIG. 3 is an enlarged sectional view of a shield portion of the disconnector of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Container 2 ... Fixed electrode 3 ... Movable electrode 4 ... Fixed electrode side shield 5 ... Arc-resistant metal 6 ... Movable electrode side shield 7 ... Conductor 8 ... Current collector 10 ... Resistance wire 11 ... Insulating cylinder

Claims (1)

Claim: What is claimed is: 1. A movable electrode and a fixed electrode, which are movable in contact with and separated from each other on a concentric shaft, are provided to face each other, and a shield is provided around the fixed electrode, and a resistance wire or a resistor is provided inside the shield. In a switchgear in which a shield with resistance is provided and the periphery of the resistance wire or resistor is fixed and supported by an insulating material, a fold is provided on the surface of the insulating material of the shield with resistance. machine.