JPH0775445B2 - Gas insulated switchgear - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a gas-insulated switchgear, and more particularly, to an improvement in the structure of a switch which is charged with switching responsibilities such as a small current, a loop current or an induced current. The applied gas insulated switchgear.

[Technical background of the invention and its problems] In recent years, the electric power system tends to have higher voltage and larger capacity,
In Japan, power transmission and transformation equipment with a voltage of 500KV and a conduction current of 8KA to 12KA has already been introduced. As a switchgear used for this purpose, a gas-insulated switchgear has been increasingly applied from the viewpoint of space reduction, high reliability, and labor saving in maintenance.

FIG. 3 shows the configuration of a disconnector as an example of a switch used in these gas-insulated switchgear. That is, the metal container 1
A fixed-side contact portion 2 and a movable-side contact portion 3 are arranged in the inside of the metal container 1 such that the fixed-side contact portion 2 and the movable-side contact portion 2 are separated by an insulating spacer 4, and the movable-side contact portion 3 is formed by an insulating spacer 5. Supported by. Further, the movable contact portion 3 is connected to the operation mechanism portion 6 via the operation rod 6a and the link 6b.

The disconnector with such a configuration usually has a small current switching duty, but in addition, it is installed on the bus side of a substation that uses a double bus system as the bus configuration of the substation. Further, the disconnecting switch is subject to a large current switching duty equivalent to a load current called a loop current. In order to fulfill such an opening / closing duty, an actuating metal is usually provided on the energizing contact portion of the switch.

The structure of the contact opening portion of such a switch is shown in FIG.
That is, the contact 7 of the fixed side contact portion 2 is composed of a main contact 7a through which a main circuit current flows and an arc contact 7b through which an arc current flows when the current is cut off. On the other hand, an arc contact 8a is also provided at the tip of the movable rod 8 of the movable side contact portion 3. These arc contacts 7b and 8a are made of metal having arc resistance.

In the switch having the above-mentioned configuration, the arc 9 is generated between the arc contact 7b of the fixed side contact part 2 and the arc contact 8a of the movable side contact part 3 when the current is cut off. Since 8a and 8a are made of metal having arc resistance, the main contact 7a is not damaged.

However, as the movable rod 8 moves in the opening direction, the length of the arc 9 becomes longer, and the arc 9 is curved due to the magnetic field generated by the thermal blow-up and the current flowing through the arc itself, and the metal shield 10 near the arc. , And the arc 9 migrates toward the metal shield 10 as shown in FIGS. 5 and 6. In such a state, the arc 9 freely moves on the surface of the metal shield 10 and melts and damages the shield 10 in the area A of FIG.

In general, since the metal shield 10 is not made of arc-resistant metal, the degree of melting loss is remarkable, not only greatly shortening the life of the switch, but also by a few times the current switching operation, as shown in FIG. As shown, the molten metal solidifies on the surface of the metal shield 10 to form the extremely sharp uneven portion 11. As a result, the equipotential distribution on the shield surface in the open state becomes as shown in FIG. 7B, which deteriorates the electric field condition on the shield surface and remarkably lowers the inter-electrode insulation performance of the disconnector.

Further, in order to eliminate the above-mentioned drawbacks, it is considered that the shield surface is cast-coated with an epoxy resin. However, in this case, it is possible to prevent the arc from migrating to the shield part, but the surface of the epoxy resin is carbonized by the heat of the arc and becomes a conductive state, which disturbs the electric field on the shield surface. It was not favorable. In addition, when a small current is turned on and off, a very high voltage is applied to the epoxy resin at the instant of re-ignition, so that the epoxy resin may be locally broken down and damaged.

If the insulation performance between contacts of the disconnector is deteriorated in this way, it is not possible to fulfill the responsibility of the disconnector, such as disconnecting the inspection part from the live line part, when inspecting the charging part of the gas-insulated switchgear. This is a serious threat to work safety. Further, the deterioration of the inter-electrode insulation performance of the disconnector has been a serious problem not only during inspection work but also in the operation of the substation, resulting in a decrease in its reliability and a shortened life of the equipment.

[Object of the Invention] The present invention has been proposed in order to solve the problems of the conventional gas-insulated switchgear as described above, and its object is to form an alumite insulating coating on the surface of a metal shield. It is an object of the present invention to provide a highly reliable and long-life gas insulation device which prevents damage to the shield and improves the cutting performance.

[Summary of the Invention] In the gas-insulated switchgear of the present invention, the shield covering the outer periphery of the fixed side contact portion of the switch is formed of aluminum, and the shield surface is subjected to alumite treatment to form an alumite layer. , The inter-electrode insulation performance of the switch has been greatly improved so that the shield surface will not be damaged by the arc.

[Embodiment of the Invention] An embodiment of the present invention will be specifically described below with reference to FIGS. 1 and 2. The same members as those of the conventional switch shown in FIGS. 3 to 7 are designated by the same reference numerals and the description thereof will be omitted.

* Structure * In the present embodiment, the base material 20a of the metal shield 20 is made of aluminum, and further, the aluminum base material 20a.
The surface of the is chemically alumite-treated to form an alumite layer 20b. Since the alumite layer 20b is formed by a chemical treatment, the adhesion with the aluminum base 20a is very good.

* Operation * In the switch of the present embodiment having such a configuration, as shown in FIG. 2, as the contact opening operation progresses, the arc 9 causes the arc contact 7b of the fixed side contact portion 2 and the movable rod. It occurs between the eight arc contacts 8a, and as the distance between both electrodes increases, the length of the arc 9 also increases. Eventually,
The arc 9 is blown up by heat and the arc contact 7b
To contact the metal shield 20 disposed on the outside of the. However, since the heat-resistant insulating coating of anodized aluminum is formed on the surface of the metal shield 20, the arc 9 will not reach the metal shield 20.
Can not be turned into.

This alumite layer 20b has excellent insulation performance,
Just by anodizing the surface of the metal shield 20,
Insulation performance can be improved by about 20%. That is, microscopically, the mechanism of the dielectric breakdown is that, immediately before the dielectric breakdown, electrons are emitted from the minute projections on the metal surface, and electron ions multiply, which leads to all-way breakdown. It is believed that when the surface is covered with an insulating coating, the initial emission of electrons is suppressed, and as a result, the insulating performance is improved.

Further, since the alumite layer 20b has excellent heat resistance,
The surface of the metal shield 20 is not damaged by the heat of the arc 9. As a result, the electric field condition on the shield surface can be maintained as it is, and the inter-electrode insulation performance of the switch can be maintained at the initial performance for a long time even when the switching operation such as loop current or induced current is performed.

Further, the arc 9 contacting the metal shield 20 at the time of switching the current is cooled by the alumite layer 20b having good thermal conductivity. This cooling effect is very efficient as compared with the case where an insulating coating is formed using a conventional epoxy resin. Further, the alumite layer can be formed thinner than the insulating coating formed using the epoxy resin, which is economical.

As described above, according to the present invention, since the arc 9 can be efficiently cooled by forming the alumite layer 20b on the surface of the metal shield 20, the current interruption performance is improved and the arc can be generated in a shorter time. Can be processed. Further, since the alumite insulating coating film applied to the surface of the metal shield can prevent melting loss of the shield surface, the electric field state of the shield surface in the open state can be maintained in the initial good state.

* Other Embodiments * The present invention is not limited to the above-mentioned embodiments, and the alumite treatment may be applied not only to the fixed side shield but also to the movable side metal shield.

[Effects of the Invention] As described above, according to the present invention, by forming the alumite insulating coating on the surface of the metal shield arranged in the switch, it is possible to prevent damage to the shield and improve the cutting performance. It is possible to provide a reliable, long-life gas insulated switchgear.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part showing an embodiment of a switch according to the present invention, and FIG. 2 is a sectional view of an essential part showing the opening operation thereof.
FIG. 4 is a sectional view of a conventional switch, and FIGS. 4 to 7 are sectional views of a main part of the conventional switch. 1 ... Metal container, 2 ... Fixed side contact part, 3 ... Movable side contact part,
4,5 ... Insulating spacer, 6 ... Operating mechanism, 6a ... Operating rod, 6b ... Link, 7 ... Contact, 7a ... Main contact, 7b ... Arc contact, 8 ... Movable rod, 8a ... Arc contact, 9 ... Arc, Ten
… Metal shield, 11… Uneven part, 20… Metal shield, 20a
… Aluminum base, 20b… alumite layer.

Claims (1)

[Claims] 1. A gas-insulated switch in which a fixed-side contact portion having a contact and a movable-side contact portion having a movable rod that can be attached to and detached from the contact are opposed to each other and housed in a container filled with an insulating gas. In the device, a fixed side shield having an inner peripheral surface facing the outer peripheral surface of the movable rod is arranged around the fixed side contact portion, the fixed side shield is formed of aluminum, and an alumite layer is formed on the surface thereof. A gas insulated switchgear characterized by the above.