A circuit breaker switchgear

Abstract

The utility model provides a circuit breaker cubical switchboard, including switch room, with switch room through pressure relief valve intercommunication's pressure relief chamber, still include mechanism room and cable room, the cable room side wall is equipped with with switch room electrical connection's incoming and outgoing line sleeve, the switch room is equipped with circuit breaker and sets up the disconnecting switch below circuit breaker, be equipped with with circuit breaker position correspondence, be used for operating circuit breaker's circuit breaker mechanism in mechanism room, and with disconnecting switch position correspondence, be used for operating the isolation mechanism of disconnecting switch, the switch room is filled with insulating gas. The utility model has the advantages of: change circuit breaker cubical switchboard's overall layout, make it with the same size as standardization 10kV cubical switchboard can adapt to higher rated voltage electrical component, effectively reduce production cost.

Description

Technical Field

[0001] This utility model relates to the field of electrical equipment, specifically to a circuit breaker switch cabinet. Background Technology

[0002] 24kV ring network switchgear is widely used in urban and industrial power distribution networks, providing reliable power supply for both indoor and outdoor power distribution. Furthermore, 24kV ring network switchgear can be used in conjunction with other power facilities such as transformers and cables to construct a complete power grid system.

[0003] As electrical switchgear, insulation performance is one of its main parameters. The State Grid and Southern Power Grid have strict requirements for parameters such as power frequency withstand voltage, lightning impulse, and partial discharge, which are essentially mandatory inspection items for all user units. Currently, most 24kV switches are based on 10kV switchgear with a wider or deeper enclosure, increasing the gas chamber space to meet phase-to-phase and phase-to-ground insulation requirements. However, this approach has the following drawbacks:

[0004] Increasing the depth and size of the installation inevitably increases the requirements for the installation foundation, as it is larger than the 10kV switchgear.

[0005] Increasing the depth of the drawing increases the strength requirements for the housing;

[0006] Simply increasing the distance without optimizing the electric field distribution within the gas chamber will result in insufficient margin in the increased limited space, making it difficult to cope with voltage fluctuations during actual operation.

[0007] Therefore, it is necessary to optimize the structure of existing 24kV switchgear. Utility Model Content

[0008] To address the problems in the existing technology, this utility model provides a circuit breaker switch cabinet.

[0009] This utility model of a circuit breaker switch cabinet includes a switch compartment, a pressure relief compartment connected to the switch compartment via a pressure relief valve, a mechanism compartment, and a cable compartment. The cable compartment has inlet and outlet bushings electrically connected to the switch compartment on its side wall. The switch compartment has a circuit breaker and a disconnecting switch located below the circuit breaker. The mechanism compartment has a circuit breaker mechanism corresponding to the position of the circuit breaker for operating the circuit breaker, and an isolation mechanism corresponding to the position of the disconnecting switch for operating the disconnecting switch. The switch compartment is filled with insulating gas.

[0010] Furthermore, the mechanism chamber is located in front of the switch chamber, the pressure relief chamber and the cable chamber are respectively located below the switch chamber, an isolation plate is provided between the pressure relief chamber and the switch chamber, a pressure relief valve is provided on the isolation plate, the cable chamber is isolated from the pressure relief chamber by a base partition and is located in front of the pressure relief chamber, and a panel module is provided in front of the cable chamber.

[0011] Furthermore, the switch chamber enclosure is made of 304 stainless steel with a thickness of not less than 2.5mm. The other cabinets and base plate of the switch cabinet, excluding the switch chamber, are made of aluminum-zinc coated steel or galvanized steel with a thickness of not less than 2mm. The panel modules, the front panel of the mechanism compartment, and the outer surface of the cover plate of the cabinet are all provided with operating holes or observation holes.

[0012] Furthermore, the upper left and right side walls of the switch compartment are also provided with three-phase side expansion bushings connected to the circuit breaker.

[0013] Furthermore, the disconnecting switch is provided with a conductive rod connected to the inlet and outlet bushings, and the conductive structures inside the switch chamber are all provided with electric field improvement structures.

[0014] Furthermore, the electric field improvement structure includes equalizing balls disposed on the conductive rod and the conductive bolt.

[0015] Furthermore, the disconnecting switch includes a switch frame, a first insulating structure and a second insulating structure disposed at corresponding positions on the switch frame, a disconnecting switch main shaft and a grounding stationary contact, a main blade stationary contact disposed on the lower surface of the first insulating structure, and a moving contact seat disposed on the upper surface of the second insulating structure. The disconnecting switch also includes a moving contact and a push rod, wherein one end of the push rod is connected to the disconnecting switch main shaft and the other end is connected to the moving contact, one end of the moving contact is hinged to the moving contact seat, and the disconnecting switch main shaft can drive the other end of the moving contact to move between the grounding stationary contact and the main blade stationary contact through the push rod.

[0016] Furthermore, the arc-extinguishing structure of the circuit breaker is a vacuum arc-extinguishing chamber, and the first insulation structure is disposed below the vacuum arc-extinguishing chamber.

[0017] Furthermore, the circuit breaker includes a circuit breaker main shaft driven by the circuit breaker mechanism. A switch crank arm is provided on the circuit breaker main shaft, and a switch crank arm guide groove is provided on the switch crank arm. The top end of the vacuum interrupter rod is located in the switch crank arm guide groove. When the switch crank arm rotates in a circular motion with the circuit breaker main shaft, the switch crank arm guide groove drives the vacuum interrupter rod to move up and down, thereby closing and opening the vacuum interrupter. When the circuit breaker is in the closed position, the switch crank arm guide groove can limit the vacuum interrupter rod, realizing self-locking of the position when closing, and preventing accidental opening due to the action of electric force. In addition, the main knife stationary contact of the disconnecting switch is provided below the circuit breaker.

[0018] Furthermore, the second insulation structure is an insulator with a creep-in skirt, the switch frame includes a lower metal crossbeam, and the moving contact seat is fixed above the lower metal crossbeam by the second insulation structure, corresponding to the position of the main blade stationary contact in the projection direction.

[0019] Compared with the prior art, the beneficial effects of this utility model are:

[0020] 1. By changing the overall layout of the circuit breaker switchgear to make it compatible with higher rated voltage electrical components with the same size as the standardized 10kV switchgear, the overall size of the product is reduced and production costs are lowered.

[0021] 2. Compared with the standardized 10kV switchgear, the lower metal crossbeam of this scheme is moved down, and the moving contact seat of the fixed moving contact is replaced by an insulator with creepage-enhancing skirt. The insulator with creepage-enhancing skirt is then installed on the metal switch frame, which increases the distance between the live parts and the switch frame, increases the electrical creepage distance, and better ensures the insulation parameters of the switch.

[0022] 3. By increasing the electric field to improve the structure and electric field distribution, the key corners are rounded and polished, and equalizing spheres are installed to effectively reduce the amount of partial discharge;

[0023] 4. The guide groove of the circuit breaker switch crank arm enables the position to be self-locked when the switch is closed, which improves the reliability and overall performance under dynamic and thermal stability conditions. Attached Figure Description

[0024] To more clearly illustrate the solutions in this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the front structure of this utility model;

[0026] Figure 2 This is a schematic diagram of the internal layout of this utility model;

[0027] Figure 3 This is a schematic diagram of the internal structure of the switch chamber and mechanism chamber of this utility model;

[0028] Figure 4 and Figure 5 This is a schematic diagram of the internal structure of the switch room;

[0029] Figure 6 This is a schematic diagram showing the first state position of the circuit breaker and disconnector;

[0030] Figure 7 This is a schematic diagram of the second state position of the circuit breaker and disconnector;

[0031] Figure 8 for Figure 7 Enlarged view of a specific area;

[0032] Figure 9 This is a schematic diagram showing the location of the third device, which includes circuit breakers and disconnect switches. Detailed Implementation

[0033] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The terms "comprising" and "having," and any variations thereof, in the specification, claims, and accompanying drawings are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the specification, claims, and accompanying drawings are used to distinguish different objects, not to describe a particular order.

[0034] In this invention, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this invention. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment to other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this invention can be combined with other embodiments.

[0035] To enable those skilled in the art to better understand the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0036] like Figure 1 and Figure 2As an embodiment of this utility model, the novel circuit breaker switchgear is a 24kV circuit breaker switchgear with rated parameters of 24kV / 630A / 25kA, and is designed and developed in accordance with, but not limited to, the following standards:

[0037] GB / T 1985-2014 High-voltage AC disconnect switches and grounding switches

[0038] GB / T 4208-2017 Degrees of protection provided by enclosures (IP code)

[0039] GB / T 3906 3.6kV~40.5kV AC metal-enclosed switchgear and controlgear

[0040] GB / T 1984-2014 High-voltage AC circuit breakers

[0041] Common technical requirements for GB / T 11022 standard for high voltage switchgear and controlgear

[0042] like Figures 1-9 As shown, the circuit breaker switchgear in this example includes a switch compartment (also called a gas box) 1, a pressure relief chamber 6 connected to the switch compartment 1 via a pressure relief valve, a mechanism compartment 7, and a cable compartment 11. The side wall of the cable compartment 11 is provided with inlet and outlet bushings 10 electrically connected to the switch compartment 1. The switch compartment 1 is provided with a circuit breaker 3 and a disconnecting switch 4 located below the circuit breaker 3. The mechanism compartment 7 is provided with a circuit breaker mechanism 8 corresponding to the position of the circuit breaker 3 for operating the circuit breaker 3, and an isolation mechanism 9 corresponding to the position of the disconnecting switch 4 for operating the disconnecting switch 4. The switch compartment 1 is filled with insulating gas. Preferably, in this example, the base 12 is separated from the pressure relief chamber 6 and the cable chamber 11 by a partition. The mechanism chamber 7 is located in front of the switch chamber 1. The pressure relief chamber 6 and the cable chamber 11 are respectively located below the switch chamber 1. An isolation plate is provided between the pressure relief chamber 6 and the switch chamber 1. A pressure relief valve 16 is provided on the isolation plate. The cable chamber 11 is located in front of the pressure relief chamber 6. A first panel is provided in front of the cable chamber 11. A second panel is provided in front of the operating chamber. Preferably, the first panel and the second panel are basically flush and together constitute the panel module 13 of the circuit breaker switch cabinet. The panel module is provided with an operating hole and an observation hole.

[0043] Preferably, in this example, the side walls on the upper left and right sides of the switch chamber 1 are also provided with three-phase side expansion terminals 2 connected to the circuit breaker 3, which are fixed to the side walls by side expansion sleeves 201.

[0044] This invention modifies the overall layout of the circuit breaker switchgear and optimizes its structure, so that the overall size of the 24kV circuit breaker switchgear in this example is consistent with that of the existing 10kV circuit breaker switchgear, without increasing the installation space. Thus, this invention can accommodate electrical components with higher rated voltages with the same size as the existing 10kV circuit breaker switchgear, effectively reducing the overall size of the product and lowering production costs.

[0045] Specifically, this example is an all-metal, fully insulated, enclosed system. The primary energized parts are housed within a sealed enclosure in switch chamber 1. The main insulating medium between energized conductors and between energized conductors and ground is SF6 insulating gas, and the arc extinguishing method is vacuum arc extinguishing. The arrangement of circuit breaker 3, disconnector 4, and busbars within the sealed gas enclosure conforms to the electrical performance requirements of GB 3906. It adopts a fixed assembly structure and a three-position integrated disconnector / grounding switch (closing, disconnecting, and grounding) with a lower isolation structure. The structural design ensures safe operation, inspection, maintenance, and handling.

[0046] In this example, the switch cabinet is made of 304 stainless steel with a thickness of not less than 2.5mm, and the gas box is welded using an automatic welding process. Other switch cabinets have cabinets and base plates made of aluminum-zinc coated steel or galvanized steel with a thickness of not less than 2mm, and the cabinet panels and covers are powder-coated.

[0047] This busbar system uses copper busbars and incorporates electric field mitigation structures at the joints to prevent electric field concentration and partial discharge. These measures will be explained in detail below with reference to the accompanying drawings.

[0048] like Figure 4 As shown, in this example, to avoid increasing the spatial structure, the positions of the circuit breakers and disconnectors were rationally arranged through multiphysics simulation optimization. In this example, there are three circuit breakers (3) and three disconnectors (4), namely a three-phase circuit breaker and a three-phase disconnector, respectively. They are positioned vertically and vertically, separated by a fixed bracket 19. The circuit breaker is positioned above the fixed bracket 19, and a fixing plate 18 secures the vacuum interrupter of the circuit breaker to ensure its radial stability and control its mechanical characteristic values. The disconnector 14 is fixed to the lower half of the fixed bracket 19. The phase structures of the three-phase circuit breaker and the three-phase disconnector are identical; this example uses one of them as an example for illustration.

[0049] Specifically, the circuit breaker 3 includes a circuit breaker main shaft 301 driven by the circuit breaker mechanism 8. The circuit breaker main shaft 301 is provided with a switch crank arm 302. The switch crank arm 302 is provided with a switch crank arm guide groove 3021. The bottom of the vacuum interrupter rod 303 is fixed to the moving end of the vacuum interrupter, and the top end 3031 is set in the switch crank arm guide groove 3021. When the switch crank arm 302 rotates in a circular motion with the circuit breaker main shaft 301, the switch crank arm guide groove drives the vacuum interrupter rod to move up and down, thereby driving the vacuum interrupter to close and open. When the circuit breaker is in the closed position, the switch crank arm guide groove can limit the vacuum interrupter rod, realizing self-locking of the position when closing, and preventing accidental opening due to the action of electric force. In addition, the main knife stationary contact of the disconnecting switch is provided below the circuit breaker.

[0050] In this example, the switch crank arm guide groove 3021 is an arc-shaped groove. One end is closer to the circuit breaker main shaft 301 than the other end, referred to as the near-distance end, and the other end is the far-distance end. When the top end 3031 of the vacuum interrupter rod 303 is at the far-distance end, the spring on the vacuum interrupter rod is compressed, and the amount of compression controls the overtravel value of the circuit breaker contacts, while the circuit breaker closes. At this time, the vacuum interrupter rod 303 is held in place by the switch crank arm guide groove, achieving self-locking of the position during closing. Figure 7 and Figure 8 As shown.

[0051] The disconnector switch 4 in this example includes a switch frame 401, a first insulating structure 410 and a second insulating structure 405 disposed at corresponding positions on the upper and lower parts of the switch frame 401, a disconnector switch main shaft 403 and a grounding stationary contact 406, a main blade stationary contact 409 disposed on the lower surface of the first insulating structure 410, and a moving contact seat 404 disposed on the upper surface of the second insulating structure 405. The disconnector switch also includes a moving contact 407 and a push rod 408. One end of the push rod 408 is connected to the disconnector switch main shaft 403 through a first hinge structure 402, and the other end is hinged to the middle of the moving contact 407. One end of the moving contact 407 is hinged to the moving contact seat 404. The disconnector switch main shaft 403 can drive the other end of the moving contact 407 to move between the grounding stationary contact 406 and the main blade stationary contact 409 through the push rod.

[0052] In this example, the dynamic engagement of circuit breaker mechanism 8 transmits the action to the main shaft of the circuit breaker through the bearing, which improves the stability of the operating mechanical characteristics, effectively ensures the mechanical strength, and improves the self-locking of the working position when closing the circuit breaker switch crank arm guide groove, thereby improving the reliability and overall performance under dynamic and thermal stability conditions.

[0053] In this example, the disconnector switch 4 is equipped with a conductive rod 5 connected to the inlet and outlet bushings 10, and the conductive structures within the switch chamber 1 are all equipped with electric field improvement structures. In this example, the copper busbar end face rounded corner 14 is polished, and equalizing balls 15 are installed at the bolt conductor connections at the ends of the conductive rod 5, which greatly reduces partial discharge.

[0054] Preferably, in this example, the arc-extinguishing structure of the circuit breaker is a vacuum interrupter 411, with a first insulation structure 410 below it, as shown in the attached diagram. Figure 6 As shown, the vacuum interrupter is fixed above the first insulating structure 410, the main blade stationary contact 409 is below the first insulating structure 410, the second insulating structure 405 is an insulator with creepage-enhancing skirts, and the switch frame 401 includes a lower metal crossbeam. Relative to the lower crossbeam of the 10kV switchgear, this lower crossbeam is lowered, increasing the distance to the main blade stationary contact 409. The moving contact seat 404 is fixed above the lower metal crossbeam via the second insulating structure 405, corresponding to the position of the main blade stationary contact 409 in the projection direction. The moving contact seat of the disconnector is conventionally mounted on a plastic beam; this design changes it to be mounted on an insulator with skirts, and the insulator is then mounted on the lower metal crossbeam 4011 of the switch frame 401. This increases the distance between the live parts and the switch frame, increases the electrical creepage distance, and better ensures the insulation parameters of the switch. The insulator is also easier to control for partial discharge characteristics, making it more convenient to meet the operation requirements of the 24kV switch. The inclusion of the first insulation structure 410 and the second insulation structure 405 in this example effectively increases the length of the moving contact arm, resulting in a larger contact opening distance at the same opening angle, thus improving the reliability of the equipment. All improvements in this invention are controlled within the installation space limits of the standardized SF6 10kV switchgear's external dimensions.

[0055] In this example, the moving contact seat is mounted on an insulator with sheds. One end of the moving contact is hinged to the moving contact seat. When the switch is initially in the open state, the other end of the moving contact is between the grounding stationary contact and the main blade stationary contact. When the main shaft of the disconnecting switch rotates, it drives the push rod to pull the moving contact counterclockwise, and the other end of the moving contact contacts the main blade stationary contact, thus achieving closing. When the moving contact is pushed clockwise, the other end of the moving contact contacts the grounding stationary contact, thus achieving grounding, thereby realizing three-position operation.

[0056] The various operating states of the circuit breaker switchgear of this utility model are as follows:

[0057] Assume the initial state is that the circuit breaker is open and the disconnector is open, such as Figure 6 As shown, at this time, the top of the vacuum interrupter rod is located in the close section of the switch crank arm guide groove 3021, and the moving contact 404 of the isolating switch is located between the grounding stationary contact 406 and the main blade stationary contact 409.

[0058] When energizing, the normal procedure is to first close the isolating switch, then close the circuit breaker. For example... Figure 7 As shown, when the circuit breaker is closed, the top of the vacuum interrupter pull rod is located at the far end of the switch crank arm guide groove 3021. The vacuum interrupter pull rod is limited and self-locked by the switch crank arm guide groove, and the moving contact 404 is connected to the main knife stationary contact 409.

[0059] During a power outage, the normal procedure is to first trip the circuit breaker, then disconnect the circuit breaker, and finally disconnect the grounding circuit breaker. Figure 9 As shown, at this time, the top of the vacuum interrupter rod is located in the close section of the switch crank arm guide groove 3021, and the moving contact 404 is connected to the grounding stationary contact 406.

[0060] As can be seen from the above, this utility model has the following advantages:

[0061] 1. The guide groove of the circuit breaker switch crank arm realizes the self-locking of the position when closing, which improves the reliability and overall performance under dynamic and thermal stability conditions;

[0062] 2. Improve the electric field distribution by rounding and polishing key areas and adding equalizing spheres to effectively reduce partial discharge.

[0063] 3. Improve the structure of the disconnecting switch by moving the lower crossbeam downward and mounting the moving contact seat, which fixes the moving contact, on an insulator with creepage-enhancing skirts, thereby increasing the electrical clearance and creepage distance.

[0064] 4. The length of the moving contact of the disconnecting switch has been increased, making the stop position of the disconnecting switch after opening farther from the stationary contact, thus making the switch safer and more reliable;

[0065] 5. By optimizing the overall layout of the switchgear, the 24kV switch cabinet is the same size as the State Grid's standardized 10kV switch cabinet, without increasing the installation space, thus saving space and effectively reducing production costs.

[0066] The specific embodiments described above are preferred embodiments of this utility model, and are not intended to limit the specific scope of this utility model. The scope of this utility model includes but is not limited to the specific embodiments described above. All equivalent changes made in accordance with this utility model are within the protection scope of this utility model.

Claims

1. A circuit breaker switchgear, characterized in that: The device includes a switch compartment, a pressure relief compartment connected to the switch compartment via a pressure relief valve, a mechanism compartment, and a cable compartment. The cable compartment has inlet and outlet bushings electrically connected to the switch compartment on its side wall. The switch compartment has a circuit breaker and a disconnecting switch located below the circuit breaker. The mechanism compartment has a circuit breaker mechanism corresponding to the position of the circuit breaker for operating the circuit breaker, and an isolation mechanism corresponding to the position of the disconnecting switch for operating the disconnecting switch. The switch compartment is filled with insulating gas.

2. The circuit breaker switchgear according to claim 1, characterized in that: The mechanism chamber is located in front of the switch chamber. The pressure relief chamber and the cable chamber are respectively located below the switch chamber. An isolation plate is provided between the pressure relief chamber and the switch chamber. A pressure relief valve is provided on the isolation plate. The cable chamber is isolated from the pressure relief chamber by a base partition and is located in front of the pressure relief chamber. A panel module is provided in front of the cable chamber.

3. The circuit breaker switchgear according to claim 2, characterized in that: The switch compartment enclosure is made of 304 stainless steel with a thickness of not less than 2.5mm. The other cabinets and base plate of the switch cabinet, excluding the switch compartment, are made of aluminum-zinc coated steel or galvanized steel with a thickness of not less than 2mm. The panel modules, front panel of the mechanism compartment, and outer surface of the cover plate of the cabinet are all provided with operating holes or observation holes.

4. The circuit breaker switchgear according to claim 1, characterized in that: The upper left and right side walls of the switch room are also equipped with three-phase side expansion bushings connected to the circuit breaker.

5. The circuit breaker switchgear according to claim 1, characterized in that: The disconnecting switch is equipped with a conductive rod connected to the inlet and outlet bushings, and the conductive structures inside the switch chamber are all equipped with electric field improvement structures.

6. The circuit breaker switchgear according to claim 5, characterized in that: The electric field improvement structure includes equalizing balls disposed on the conductive rod and the conductive bolt.

7. The circuit breaker switchgear according to claim 1, characterized in that: The disconnecting switch includes a switch frame, a first insulating structure and a second insulating structure disposed at corresponding positions on the switch frame, a disconnecting switch main shaft and a grounding stationary contact, a main blade stationary contact disposed on the lower surface of the first insulating structure, and a moving contact seat disposed on the upper surface of the second insulating structure. The disconnecting switch also includes a moving contact and a push rod, wherein one end of the push rod is connected to the disconnecting switch main shaft and the other end is connected to the moving contact, one end of the moving contact is hinged to the moving contact seat, and the disconnecting switch main shaft can drive the other end of the moving contact to move between the grounding stationary contact and the main blade stationary contact through the push rod.

8. The circuit breaker switchgear according to claim 7, characterized in that: The arc-extinguishing structure of the circuit breaker is a vacuum arc-extinguishing chamber, and the first insulation structure is disposed below the vacuum arc-extinguishing chamber.

9. The circuit breaker switchgear according to claim 8, characterized in that: The circuit breaker includes a circuit breaker main shaft driven by the circuit breaker mechanism. A switch crank arm is provided on the circuit breaker main shaft, and a switch crank arm guide groove is provided on the switch crank arm. The top end of the vacuum interrupter pull rod is located in the switch crank arm guide groove. When the switch crank arm rotates in a circular motion with the circuit breaker main shaft, the switch crank arm guide groove drives the vacuum interrupter pull rod to move up and down, thereby driving the vacuum interrupter to close and open. When the circuit breaker is in the closed position, the switch crank arm guide groove can limit the vacuum interrupter pull rod, realizing self-locking of the position when closing, and preventing accidental opening due to the action of electrodynamic force. In addition, the main knife stationary contact of the disconnecting switch is provided below the circuit breaker.

10. The circuit breaker switchgear according to claim 7, characterized in that: The second insulation structure is an insulator with a creepage-enhancing skirt. The switch frame includes a lower metal crossbeam. The moving contact seat is fixed above the lower metal crossbeam by the second insulation structure, and its position corresponds to that of the main blade stationary contact in the projection direction.

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