JP7576190B2 - Switchgear - Google Patents

Description

The present invention relates to a high-voltage switchgear molded from resin.

Some switches that handle high voltages, including vacuum circuit breakers, disconnectors, and load switches, are molded from resin to protect the surrounding area from the high electric field around the equipment and to improve insulation performance.

An example of a prior art document in this technical field is Patent Document 1. Patent Document 1 discloses a vacuum switchgear that includes a vacuum interrupter having a fixed electrode and a movable electrode that comes into contact with or separates from the fixed electrode, an insulated operating rod that is arranged coaxially with a movable conductor connected to the movable electrode, and a solid insulator that covers the vacuum interrupter and the insulated operating rod.

JP 2019-32994 A

In Patent Document 1, an insulating operating rod is used to connect the main circuit part, which is a high-potential switch part, to an operating device at ground potential connected to the insulating operating rod. In order to ensure sufficient insulation performance, the dimensions of the insulating operating rod must be lengthened to ensure insulation distance. This poses the problem of not being able to miniaturize the device. In addition, to achieve miniaturization, it is possible to shorten the dimensions of the insulating operating rod and ensure insulation performance by filling the space in the insulating operating rod part with a medium with high insulation strength, such as insulating gas or vacuum, but this is not sufficient and is expensive, which is a problem.

In view of the above problems, the present invention aims to provide a switchgear that can be miniaturized.

One example of the present invention is a switch comprising a vacuum interrupter having an opening/closing section made up of a fixed electrode and a movable electrode that comes into contact with or separates from the fixed electrode, a main circuit section made up of a first bushing conductor connected to the fixed electrode and electrically connected to a fixed conductor drawn out of the vacuum interrupter, and a second bushing conductor connected to the movable electrode and electrically connected to the movable conductor drawn out of the vacuum interrupter, and an operating device directly connected to the movable conductor drawn out of the vacuum interrupter and that moves the movable electrode to operate the opening/closing section, the operating device and the main circuit section being configured as a single unit molded from a solid insulating material.

According to the present invention, it is possible to provide a switch that can be made compact.

1 is a cross-sectional view taken along a plane including a central axis of a vacuum circuit breaker according to an embodiment of the present invention. FIG. 2 is a schematic diagram showing the functional configuration of a vacuum circuit breaker according to an embodiment. FIG. 4 is a schematic diagram of another functional configuration of the vacuum circuit breaker according to the embodiment. FIG. 1 is a cross-sectional view taken along a plane including a central axis of a conventional vacuum circuit breaker.

Below, an embodiment of the present invention is explained with reference to the drawings.

In this embodiment, a vacuum circuit breaker for a railway vehicle is used as an example of a switchgear. Figure 4 is a cross-sectional view of a conventional vacuum circuit breaker, which is the premise of the present invention, cut along a plane including the central axis.

For example, a railway vehicle is made up of multiple cars, with a high-voltage pull-through cable arranged on the roof of each car, and the railway vehicle receives power from the electric wire via a pantograph connected to this high-voltage pull-through cable. The high-voltage pull-through cable of each car is connected between the cars by straight joints, and branches out toward the underside of the vehicle floor by a T-branch joint. The T-branch joint and the straight joint then form an integrated switch. This switch is attached to a fixed part of the railway vehicle when used.

In FIG. 4, the vacuum circuit breaker 70 has electrical connections 10A, 10B, and 10C, and electrical connections 10B and 10C are electrically connected inside the vacuum circuit breaker 70, with electrical connections 10B and 10C forming a T-branch joint. Between electrical connections 10A and 10B and 10C, an opening/closing section is provided inside the vacuum circuit breaker 70, which is comprised of a fixed electrode and a movable electrode, as described below, and electrical connections 10A, 10B, and 10C form a straight joint. Although not shown, the vacuum circuit breaker 70 is used with a T-shaped cable head connected to electrical connections 10A, 10B, and 10C. The vacuum circuit breaker 70 is attached to a railroad car with the vacuum circuit breaker 70 fixed to a base 71 via a stay.

The vacuum circuit breaker 70 also includes a vacuum interrupter 1 that is made up of a fixed electrode 3, a movable electrode 5 that comes into contact with or separates from the fixed electrode 3, and an arc shield 6 that covers the periphery of the fixed electrode 3 and the movable electrode 5. The outer container of the vacuum interrupter 1 maintains a vacuum state inside. The vacuum circuit breaker 70 extinguishes the arc within the vacuum container by utilizing the fact that the arc diffuses rapidly into the vacuum. This configuration is also used in vacuum switches and is used from high voltage to extra-high voltage. It is also used in high voltage distribution boards due to its durability and ease of maintenance.

The fixed electrode 3 is connected to a fixed conductor, which is pulled out of the vacuum interrupter 1 and electrically connected to bushing conductors 12B and 12C on the fixed conductor side. The movable electrode 5 is connected to a movable conductor, which is pulled out of the vacuum interrupter 1 and electrically connected to bushing conductor 12A on the movable conductor side.

Here, a high voltage of, for example, 25 kV to 30 kV is applied to the opening and closing section consisting of the fixed electrode and the movable electrode. Meanwhile, the operating device 40, which is necessary for moving the movable electrode and operating the opening and closing section consisting of the fixed electrode and the movable electrode, is at ground potential, and the electrical circuit that constitutes the operating device 40 is a low-voltage circuit of, for example, 100 V DC.

Therefore, to insulate the high potential opening and closing part from the operator at ground potential, an insulated operating rod 30 is provided, with one end connected to the movable conductor and the other end connected to the operator 40. By operating the insulated operating rod 30 with the operator 40, the movable electrode is moved while maintaining the vacuum state of the vacuum interrupter 1, thereby operating the opening and closing part composed of the fixed electrode and movable electrode. The operator 40, for example, combines a spring with a permanent magnet and an electromagnet, and generates a driving force by switching on and off the current to the coil that constitutes the electromagnet.

In addition, the main circuit section 20, which is composed of the vacuum interrupter 1, bushing conductors 12B and 12C on the fixed conductor side, and bushing conductor 12A on the movable conductor side, and the air insulating space 31 around the insulating operating rod 30 are integrally molded so as to cover the outer periphery with a solid insulating member 15 made of a thermosetting resin such as epoxy resin, to form the molded insulator 50 shown by the dotted line.

Thus, conventionally, an insulating operating rod is used to connect a high-potential main circuit section with an operating device at ground potential. Therefore, in order to ensure sufficient insulation performance, it is necessary to lengthen the dimensions of the insulating operating rod to ensure an insulating distance. This has led to the problem that it cannot be made compact. Also, for the sake of miniaturization, it is possible to shorten the dimensions of the insulating operating rod and ensure insulation performance by filling the space in the insulating operating rod with a medium with high insulating strength, such as insulating gas or vacuum, but this is not sufficient and is expensive, which has been an issue.

Therefore, in this embodiment, the operating device is directly connected to the main circuit section and molded with resin, eliminating the need for the air insulation space 31 and making the device smaller. This embodiment will be described in detail below.

Figure 1 is a cross-sectional view of the vacuum circuit breaker of this embodiment cut along a plane including the central axis. In Figure 1, the same components as those in Figure 4 are given the same reference numerals, and their explanation will be omitted. Figure 1 differs from Figure 4 in that there is no insulating operating rod 30 or air insulating space 31, and the operating device 40 and main circuit section 20 are directly connected and the whole is molded as a single unit using a solid insulating member 15 made of resin.

As shown in FIG. 1, the vacuum circuit breaker 80 in this embodiment connects the movable conductor drawn out of the vacuum interrupter 1 of the main circuit section 20 to the operating device 40, and directly connects the operating device 40 to the main circuit section 20. This eliminates the need for an insulating distance between the main circuit section and the operating device, and the need for the insulating operating rod 30 and air insulating space 31, making it possible to reduce the size. By directly connecting the operating device 40 to the main circuit section 20, the operating device 40 also becomes a current-carrying section like the main circuit section 20. Therefore, since it is not a current-carrying path, no current flows, but insulation is required. For this reason, the operating device 40 and the main circuit section 20 are entirely molded to form a molded insulator 51, and the molded insulator 51 is surface-grounded.

In addition, because the controller is operated by a low-voltage circuit, it is necessary to avoid contact with the high-voltage parts of the main circuit. To achieve this, the drive circuit, auxiliary circuit, and other components are separated from the controller, and only the mechanical parts are molded.

Figure 2 is a schematic diagram of the functional configuration of the vacuum circuit breaker in this embodiment. In Figure 2, among the components in the conventional operating device, namely, a mechanical part 42, a driving source 43 such as an electromagnet consisting of a driving coil, an auxiliary circuit 44 such as a proximity sensor or a magnetic sensor that monitors the state of the opening and closing contacts, and other components 45 such as an operation counter or a thermometer, the components other than the mechanical part 42 are arranged outside the solid insulating member 15. As a result, even if the operating device is operated with a low-voltage circuit, the electric circuit part is outside the mold, so that it is possible to avoid contact with the high-voltage part of the main circuit part. In Figure 2, the mechanical part 42 is arranged inside the case 41, and the case 41 is used as a mold when molding, and its periphery is molded. In addition, the case 41 and the mechanical part 42 are fixed to the main circuit part 20. The fixing structure may be a screw or pin structure.

Figure 3 is a schematic diagram of another functional configuration of the vacuum circuit breaker in this embodiment. In Figure 3, the same components as in Figure 2 are given the same reference numerals, and their explanation will be omitted. Figure 3 differs from Figure 2 in that it has an electromagnet 46 as the drive source 43, and a plunger 47, a connecting part contact spring 48, and an interrupter spring 49 as the mechanical part 42.

When all parts of the actuator other than the mechanical part are placed outside the mold to insulate it from the high-voltage parts of the main circuit, the electrical circuit part of the actuator cannot be physically connected to the mechanical part. For this reason, a non-contact electromagnet 46 is used as the drive source 43, and the plunger 47 as the mechanical part 42 is driven non-contact to operate the opening and closing part of the main circuit. In addition, by using non-contact types for the auxiliary circuits 44 such as proximity sensors and magnetic sensors, and other parts 45 such as an operation counter and a thermometer, the condition inside the mold can be detected.

In this embodiment, the main circuit and mechanical parts are entirely covered with a mold, so there is concern about the effect of heat generation when electricity is applied. Therefore, the case 41 is made of, for example, aluminum casting, and the heat is dissipated through the case 41 to suppress heat generation in the conductors.

In addition, the movable conductor pulled out of the vacuum interrupter 1 of the main circuit section 20 is connected to the bushing conductor 12A using a copel, braided wire, multi-contact, etc.

In addition, because the main circuit section and the mechanical section are entirely covered with a mold, maintenance of the mechanical section inside the mold becomes difficult. To address this, a low-friction material can be used for the bearings, making them grease-free and adjustment-free. Alternatively, the mold for the main circuit section and the mechanical section can be separated, and maintenance can be performed by removing part of the mold. When using a separate type, it is necessary to configure it so that insulation breakdown does not occur at the joints of the resin. To achieve this, the joints can be structured to be longer in distance so that the surface pressure at the resin joints is higher, or the joints can be structured so that they fit together via an elastic body. Furthermore, insulating grease or a sealant such as an O-ring can be used at the joints of the joints.

In addition, the hardening temperature during molding is, for example, 140°C, and there is concern that the mechanical parts of the controller may be damaged at that hardening temperature. This can be addressed by selecting parts with matching temperature specifications.

Furthermore, the overall sealing structure prior to molding can be achieved by covering the mechanical parts with a case and sealing the case at the mating surfaces with the conductors of the main circuit section, etc.

In addition, the vacuum circuit breaker in this embodiment does not require an insulating operating rod 30, making it possible to reduce weight, and furthermore, since the main circuit section and the entire mechanical section are covered with a mold, the sound generated when the opening and closing section operates is contained by the mold, making it possible to reduce noise.

As described above, according to this embodiment, by directly connecting the operating device to the main circuit section and molding it with resin, it is possible to provide a vacuum circuit breaker that eliminates the need for an insulated operating rod and allows for miniaturization.

Although the embodiment has been described, the present invention can reduce the amount of materials used by achieving miniaturization. This can reduce carbon emissions and prevent global warming, and contribute to achieving the Sustainable Development Goals (SDGs), particularly item 7, energy.

Furthermore, the present invention is not limited to the above-mentioned embodiments, but includes various modified examples. For example, the above-mentioned embodiments have been described using a vacuum circuit breaker for a railway vehicle as an example, but they can also be applied to switches that handle high voltages, including disconnectors and load switches. Furthermore, the above-mentioned embodiments have been described in detail to clearly explain the present invention, and are not necessarily limited to those that include all of the configurations described.

1: Vacuum interrupter, 3: Fixed electrode, 5: Movable electrode, 6: Arc shield, 10A, 10B, 10C: Electrical connection part, 12A, 12B, 12C: Bushing conductor, 15: Solid insulating member, 20: Main circuit part, 30: Insulated operating rod, 31: Air insulating space, 40: Operating device, 41: Case, 42: Mechanical part, 43: Driving source, 44: Auxiliary circuit, 45: Other parts, 46: Electromagnet, 47: Plunger, 48: Connecting part contact spring, 49: Breaking spring, 50, 51: Molded insulator, 70, 80: Vacuum circuit breaker, 71: Base

Claims (1)

a vacuum interrupter having an opening/closing section formed of a fixed electrode and a movable electrode that comes into contact with or separates from the fixed electrode; a main circuit section formed of a first bushing conductor connected to the fixed electrode and electrically connected to a fixed conductor drawn out to the outside of the vacuum interrupter; and a second bushing conductor connected to the movable electrode and electrically connected to a movable conductor drawn out to the outside of the vacuum interrupter;
an operating device that is directly connected to the movable conductor drawn out of the vacuum interrupter and that operates the opening and closing unit by moving the movable electrode;
The operating device and the main circuit unit are integrally molded from a solid insulating material,
The mechanical part and the main circuit part of the operating device are molded using the solid insulating material,
a drive circuit for driving the mechanical portion is disposed outside the mold;
Other parts of the operating device other than the mechanical part are arranged outside the molded part ,
A switch characterized in that the other component is a non-contact type operation counter .

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