Grounding switch with arc striking structure and arc extinguishing structure

Abstract

The invention relates to the field of high-voltage switch equipment, in particular to a grounding switch with an arc striking structure and an arc extinguishing structure, which comprises a static contact assembly and a moving contact assembly, the moving contact assembly can perform opening and closing rotation relative to the static contact assembly, and the static contact assembly comprises a main contact, a spoiler and a static arc contact which are connected in sequence; the arc extinguishing structure comprises an arc extinguishing chamber located at the outer end of the main contact, and the moving contact assembly passes through the arc extinguishing chamber in a partial path of opening rotation. A spoiler and a static arc contact are arranged in a static contact assembly, so that when the grounding switch is switched on, a moving contact assembly firstly contacts the static arc contact and then contacts a main contact, the static arc contact plays an arc striking role, burning loss of the main contact is avoided, the number of short-circuit switching-on and switching-off is increased, meanwhile, shunting can be achieved, the electric conductivity can be improved, loop resistance can be reduced, and peak withstand current can be improved. And the open-circuit current duration is prolonged. And meanwhile, the arc extinguish chamber rapidly extinguishes the arc generated by opening and closing, so that the arc is prevented from being led to the main contact, and the performance of the grounding switch is better.

Description

Technical Field

[0001] The present invention relates to the field of high-voltage switchgear, and in particular to a grounding switch with an arc striking structure and an arc extinguishing structure. Background Art

[0002] In power transmission and distribution systems, grounding switches are crucial devices for ensuring the safety of power equipment inspection and maintenance. In actual operation, when a grounding switch is closed, particularly when facing high currents such as short-circuit currents, strong arcing occurs between the contacts. Frequent exposure to arcing can lead to contact wear and poor contact in conventional grounding switches. This not only reduces the number of short-circuit closings, but also compromises the grounding switch's ability to withstand current, threatening the safe and stable operation of the power system. Summary of the Invention

[0003] The purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art and to provide a grounding switch with an arc striking structure and an arc extinguishing structure.

[0004] The technical solution adopted by the present invention is as follows: a grounding switch with an arc striking structure and an arc extinguishing structure, comprising a static contact assembly and a moving contact assembly, wherein the moving contact assembly can be opened and closed relative to the static contact assembly. The static contact assembly includes a main contact, a baffle, and a static arc contact connected in sequence. The baffle has a resistance greater than that of the main contact and greater than that of the static arc contact. When the moving contact assembly rotates to close the switch, it contacts the static arc contact and the main contact in sequence. The arc extinguishing structure includes an arc extinguishing chamber located at the outer end of the main contact, and the moving contact assembly passes through the arc extinguishing chamber during a partial path of opening rotation.

[0005] The moving contact assembly includes a pair of parallel and oppositely arranged grounding knives, and the inner side surface of the grounding knives is provided with a moving contact area; The main contact has a main contact plate, and the moving contact area of ​​the grounding knife contacts the side of the main contact plate to form direct conduction between the moving contact assembly and the main contact; The static arc contact is located below the main contact plate and is separated from the main contact by a baffle plate. The width of the static arc contact is adapted to the width of the main contact plate. The moving contact area of ​​the grounding knife contacts the side of the static arc contact to form direct conduction between the moving contact assembly and the static arc contact. The static arc contact protrudes from the front end of the main contact plate so that the static arc contact contacts the moving contact assembly before the main contact plate contacts the moving contact assembly.

[0006] The lower surface of the spoiler is a plane, and the static arc contact includes a connecting plate that fits the lower surface of the spoiler and is fixedly connected to the spoiler, and an inclined plate formed by extending and bending the outer end of the connecting plate downward. The spacing between the inclined plate and the main contact plate gradually increases from the inside to the outside, and the inclined plate protrudes from the front end of the main contact plate so that the inclined plate contacts the moving contact assembly before the main contact plate contacts the moving contact assembly.

[0007] The spoiler is a flat plate, and a groove adapted to the spoiler is provided below the main contact plate. The spoiler is embedded in the groove and its thickness is greater than the depth of the groove so that its lower surface is raised relative to the lower surface of the main contact plate.

[0008] The moving contact assembly includes an elastic acting member, a connecting shaft, a limit plate, and a spacer ring. The limit plate is provided in a pair and is respectively located on the outside of the two grounding knives. The spacer ring is located between the two grounding knives. The connecting shaft passes through the limit plate, the grounding knife, and the spacer ring. The elastic acting member is located on the outside of the limit plate so that it forms an inward elastic force on the grounding knife.

[0009] The spacer ring is rollable relative to the connecting shaft. In a partial path of the closing rotation, the spacer ring abuts against the static arc contact and rolls relative to the static arc contact.

[0010] The elastic acting member is a disc spring assembly.

[0011] The arc extinguishing chamber comprises a bracket and a plurality of arc extinguishing grids fixed on the bracket, and an arc striking gap is formed between the outer end of the static arc contact and the plurality of arc extinguishing grids.

[0012] The bracket includes a connecting block fixedly connected to the outer end of the main contact and a fixing rod at the outer end of the connecting block. The fixing rod is arranged at an angle and the inclination direction tends to the rotation direction of the moving contact assembly. A plurality of arc-extinguishing grids are arranged in sequence along the inclination direction of the fixing rod. The arc-extinguishing grids are provided with openings for the moving contact assembly to extend into.

[0013] The fixing rod includes a flat connecting plate and a plurality of sequentially arranged limiting partitions at the lower end of the flat connecting plate. Adjacent limiting partitions are connected by longitudinal partitions perpendicular to the flat connecting plate to form two slots. The outer peripheral surface of the limiting partition is an arc surface, and each slot on the limiting partition is provided with a card slot. Two inserts adapted to the slots are provided on the side of the arc extinguishing grid away from the opening, and a clamping block adapted to the slots is provided on the inserts. The clamping block cooperates with the slots to secure the arc extinguishing grid to the fixing rod through a snap connection. The arc extinguishing grid is protruded relative to the fixing rod on both sides of the two inserts; The moving contact assembly includes a pair of parallel and oppositely arranged grounding knives, the inner side of the grounding knives is provided with a moving contact area, and the position of the grounding knives corresponds to the position of the arc extinguishing grid relative to the fixed rod protrusion.

[0014] The beneficial effects of the present invention are as follows: By providing a baffle and a static arc contact in the static contact assembly, the present invention enables the moving contact assembly to first contact the static arc contact and then the main contact when the grounding switch is closed, allowing the static arc contact to act as an arc starter, thereby preventing burnout of the main contact. This increases the number of short-circuit closings and, at the same time, shunting current, improving conductivity, reducing loop resistance, increasing peak withstand current, and extending the duration of the circuit-breaking current. Furthermore, the arc extinguishing chamber quickly extinguishes the arc generated by opening and closing, preventing the arc from being drawn to the main contact, thereby improving the performance of the grounding switch. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, without paying any creative work, other drawings obtained based on these drawings still fall within the scope of the present invention.

[0016] Figure 1 A schematic structural diagram of an embodiment of the present invention; Figure 2 A cross-sectional view of an embodiment of the present invention; Figure 3 for Figure 2 A magnified schematic diagram of part A; Figure 4 This is a partial enlarged view of a hidden arc extinguishing structure according to an embodiment of the present invention; Figure 5 This is an exploded view of a static contact assembly according to an embodiment of the present invention; Figure 6 This is a structural diagram of a moving contact assembly according to an embodiment of the present invention; Figure 7 This is an exploded view of a moving contact assembly according to an embodiment of the present invention; Figure 8 This is a schematic structural diagram of an arc extinguishing chamber according to an embodiment of the present invention; Figure 9 This is a structural schematic diagram of a fixing rod according to an embodiment of the present invention; Figure 10 This is a schematic structural diagram of an arc-extinguishing grid according to an embodiment of the present invention; Figure 11 A side view of an embodiment of the present invention; Figure 12 A partially enlarged view of the main view of an embodiment of the present invention; In the figure, the static contact assembly 100, the main contact 110, the main contact plate 111, the main fixed plate 112, the baffle 120, the static arc contact 130, the connecting plate 131, the inclined plate 132, the first guide contact area 133, the static arc contact contact area 134, the moving contact assembly 200, the grounding knife 210, the moving contact area 211, the elastic action member 220, the connecting shaft 230, the limiting plate 240, the spacer ring 250, the operating shaft 300, the arc extinguishing chamber 400, the bracket 410, the connecting block 411, the fixing rod 412, the flat connecting plate 4121, the limiting spacer 4122, the longitudinal spacer 4123, the slot 4124, the arc extinguishing grid 420, the opening 421, the insert 422, and the block 423. DETAILED DESCRIPTION

[0017] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention will be described in further detail below with reference to the accompanying drawings.

[0018] It should be noted that all expressions using "first" and "second" in the embodiments of the present invention are for the purpose of distinguishing two non-identical entities with the same name or non-identical parameters. It can be seen that "first" and "second" are only for the convenience of expression and should not be understood as limitations on the embodiments of the present invention. Subsequent embodiments will not explain this one by one.

[0019] The terms used herein, such as "up," "down," "front," "back," "left," "right," "inside," "outside," "top," "bottom," and "side," are intended solely to refer to the accompanying drawings. These terms are intended to illustrate and facilitate understanding of the present invention and are not intended to limit its scope.

[0020] The grounding switch generally includes a static contact assembly 100 and a moving contact assembly 200. The moving contact assembly 200 can rotate around the axis of the operating shaft 300 under the drive of the operating shaft 300, thereby being able to perform opening and closing rotation relative to the static contact assembly 100. After the closing rotation is completed, the moving contact assembly 200 contacts the static contact assembly 100 to form conduction.

[0021] Based on the structure of the grounding switch, the present application optimizes the structure of the static contact assembly 100, and adds an arc striking structure and an arc extinguishing structure. Specifically, Figure 1-4As shown, the static contact assembly 100 includes a main contact 110, a baffle 120, and a static arc contact 130 connected in sequence. The resistance of the baffle 120 is greater than that of the main contact 110 and greater than that of the static arc contact 130. When the circuit breaker rotates, the moving contact assembly 200 contacts the static arc contact 130 and the main contact 110 in sequence, that is, the moving contact assembly 200 contacts the static arc contact 130 first and then contacts the main contact 110, so that the static arc contact 130 plays an arc-starting role to avoid burning of the main contact. At the same time, when the circuit breaker is closed, the static arc contact 130 and the main contact 110 are both in contact with the moving contact assembly 200 and are conductive. The static arc contact 130 is electrically connected to the main contact 110 through the baffle 120, forming a shunt effect, thereby improving conductivity, reducing loop resistance, increasing peak withstand current, and increasing circuit-breaking current duration. The arc extinguishing structure includes an arc extinguishing chamber 400 located at the outer end of the main contact 110. The moving contact assembly 200 passes through the arc extinguishing chamber 400 during part of the path of the opening rotation. By adding the arc extinguishing chamber 400, the formed arc is extinguished in time, thereby preventing the arc from being directed to the main contact 110 and the moving contact assembly 200.

[0022] The main contact 110 carries the majority of the current and can be made of conventional materials used in the art for electrical contacts, such as copper. The static arc contact 130, which initiates the arc, requires a highly conductive and arc-resistant material, such as copper-tungsten alloy. The baffle 120, located between the main and static arc contacts 110 and 130, acts as a current blocker, limiting the arc from reaching the main contact 110. It requires a material with less conductive properties, such as chromium bronze.

[0023] like Figure 4 、 Figure 5 As shown, the main contact 110 is integrally formed and has a main contact plate 111 and a main fixed plate 112. The main fixed plate 112 is a T-shaped structure. A connecting structure is provided on the main fixed plate 112 for connecting and fixing the static contact assembly 100. The main contact plate 111 is located at the lower end of the main fixed plate 112 and the two sides are raised relative to the lower end of the main fixed plate 112. The baffle 120 is connected to the lower end of the main contact plate 111 and the static arc contact 130 is connected to the lower end of the baffle 120. The static arc contact 130 is separated from the main contact 110 by a certain distance through the baffle 120. The width of the static arc contact 130 is adapted to the width of the main contact plate 111. Figure 6As shown, the moving contact assembly 200 includes a pair of parallel and oppositely arranged grounding knives 210, and the inner side surface of the grounding knife 210 is provided with a moving contact area 211; the moving contact area 211 of the grounding knife 210 contacts the side surface of the main contact plate 111 to form a direct conduction between the moving contact assembly 200 and the main contact 110; the moving contact area 211 of the grounding knife 210 contacts the side surface of the static arc contact 130 to form a direct conduction between the moving contact assembly 200 and the static arc contact 130; the static arc contact 130 protrudes from the front end of the main contact plate 111 so that the static arc contact 130 contacts the moving contact assembly 200 before the main contact plate 111 contacts the moving contact assembly 200.

[0024] Specifically, such as Figure 4 、 Figure 5 As shown, the lower surface of the spoiler plate 120 is flat. The static arc contact 130 includes a connecting plate 131 that fits against and is fixedly connected to the lower surface of the spoiler plate 120, and an inclined plate 132 formed by a downwardly extending and bent outer end of the connecting plate 131. The spacing between the inclined plate 132 and the main contact plate 111 gradually increases from the inside to the outside. The inclined plate 132 protrudes beyond the front end of the main contact plate 111, allowing the inclined plate 132 to contact the moving contact assembly 200 before the main contact plate 111 and the moving contact assembly 200. The tilt angle of the inclined plate 132 is designed to maintain a safe distance between the arc generation location and the main contact plate 111. The arc generated at the moment the moving contact assembly 200 contacts the inclined plate 132 is concentrated on the surface of the inclined plate 132, while the main contact plate 111 has not yet made contact, completely avoiding the high-temperature ablation caused by the arc. The tight fit between the connecting plate 131 and the lower surface of the baffle plate 120 ensures reliable electrical conduction between the static arc contact and the baffle plate. When the moving contact assembly 200 contacts the inclined plate 132, current flows through the static arc contact-baffle path. The baffle plate's resistance limits the initial current peak. When the main contact plate 111 contacts, the main contact path is formed, and current smoothly transfers from the static arc contact path to the main contact path.

[0025] The spoiler 120 is a flat plate. A groove adapted to the spoiler 120 is provided below the main contact plate 111 . The spoiler 120 is embedded in the groove and its thickness is greater than the groove depth so that its lower surface is raised relative to the lower surface of the main contact plate 111 .

[0026] like Figure 5As shown, the contact surfaces on both sides of the static arc contact 130 have a first guide contact area 133 and a static arc contact contact area 134 connected in sequence. When the switch is closed, the dynamic contact area 211 of the grounding knife 210 contacts the first guide contact area 133 and the static arc contact contact area 134 in sequence, and in the closed position, the dynamic contact area 211 of the grounding knife 210 maintains contact with the static arc contact contact area 132.

[0027] like Figure 6 、 Figure 7 As shown, the movable contact assembly 200 includes an elastic member 220, a connecting shaft 230, a limiting plate 240, and a spacer ring 250. A pair of limiting plates 240 are provided, one located outside each of the two grounding switches 210. The spacer ring 250 is located between the two grounding switches 210. The elastic member 220 is located outside the two limiting plates 240. The elastic abutment acts on the grounding switches 210 through the limiting plates 240, generating an inward elastic force on the grounding switches 210 to ensure sufficient contact pressure during the closing process. Specifically, the elastic member 220 is a disc spring assembly.

[0028] The spacer ring 250 is rollable relative to the connecting shaft 230. During a portion of the closing rotation, the spacer ring 250 abuts against the static arcing contact 130 and rolls relative to the static arcing contact 130. This improves the contact stability between the moving contact assembly 200 and the static contact assembly 100 and prevents sticking or uneven wear.

[0029] The parameters of the grounding switch with an additional arc-starting structure in this embodiment are compared as follows: rated voltage 12 kV, rated frequency 50 Hz, rated peak withstand current 125 kA, rated short-time withstand current 50 kA, short-circuit duration 4 s, rated short-circuit making current 125 kA, and rated power frequency withstand voltage 42 kV.

[0030] like Figure 8 As shown, the arc extinguishing chamber 400 includes a bracket 410 and a plurality of arc extinguishing grids 420 fixed to the bracket 410. An arc striking gap is formed between the outer end of the static arc contact 130 and the plurality of arc extinguishing grids 420. The bracket 410 includes a connecting block 411 fixedly connected to the outer end of the main contact 110 and a fixing rod 412 at the outer end of the connecting block 411. The fixing rod 412 is arranged obliquely and the inclination direction tends to the rotation direction of the moving contact assembly 200. The plurality of arc extinguishing grids 420 are arranged in sequence along the inclination direction of the fixing rod 412. The arc extinguishing grids 420 are provided with openings 421 for the moving contact assembly 200 to extend into. Figure 11 、 Figure 12As shown, the moving contact assembly 200 sequentially passes through the openings 421 of several arc-extinguishing grids 420 during its rotation. During opening, the arc between the static contact assembly 100 and the moving contact assembly 200 lengthens as the moving contact assembly 200 moves. Immediately after separation, the arc energy is high. The arc-extinguishing chamber 400 of this embodiment uses several arc-extinguishing grids 420 to cut and cool the stretched arc formed during separation, extinguishing the arc. The bracket 410 is made of insulating material, and the connecting block 411 is fixedly connected to the outer end of the main contact 110 via bolts.

[0031] like Figure 9 As shown, the fixing rod 412 includes a flat connecting plate 4121 and a plurality of sequentially arranged limiting partitions 4122 at the lower end of the flat connecting plate 4121. Adjacent limiting partitions 4122 are connected by longitudinal partitions 4123 perpendicular to the flat connecting plate 4121 to form two slots. The outer peripheral surface of the limiting partition 4122 is an arc surface, and a card slot 4124 is provided on each slot of the limiting partition 4122. Figure 10 As shown, the arc quenching grid 420 is provided with two inserts 422 that fit into the slots on one side away from the opening 421, and a latch 423 that fits into the latch slot 4124 is provided on the insert 422. The latch 423 cooperates with the latch slot 4124 to secure the arc quenching grid 420 to the fixing rod 412 via a snap connection. The arc quenching grid 420 protrudes relative to the fixing rod 412 on both sides of the two inserts 422, and the position of the grounding knife 210 corresponds to the position of the arc quenching grid 420 protruding relative to the fixing rod 412. This structure facilitates the assembly of the arc quenching chamber and leaves the upper end region of the adjacent arc quenching grid 420 corresponding to the grounding knife 210 open and unobstructed by the bracket 410, facilitating the rapid discharge of arc airflow cut and cooled by the arc quenching grid 420.

[0032] The above disclosure is merely a preferred embodiment of the present invention and certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. A grounding switch with an arc striking structure and an arc extinguishing structure, comprising a static contact assembly (100) and a moving contact assembly (200), wherein the moving contact assembly (200) can be opened and closed relative to the static contact assembly (100), and is characterized in that: The static contact assembly comprises a main contact (110), a baffle (120), and a static arc contact (130) connected in sequence; the baffle (120) has a resistance greater than that of the main contact (110) and greater than that of the static arc contact (130); and the moving contact assembly (200) contacts the static arc contact (130) and the main contact (110) in sequence when rotating for closing; The arc extinguishing structure comprises an arc extinguishing chamber (400) located at the outer end of the main contact (110), and the moving contact assembly (200) passes through the arc extinguishing chamber (400) during a partial path of opening rotation.

2. The grounding switch with arc striking structure and arc extinguishing structure according to claim 1, characterized in that: The moving contact assembly (200) comprises a pair of mutually parallel and oppositely arranged grounding knives (210), wherein the inner side surfaces of the grounding knives (210) are provided with a moving contact area (211); The main contact (110) has a main contact plate (111), and the movable contact area (211) of the grounding knife (210) contacts the side of the main contact plate (111) to form direct conduction between the movable contact assembly (200) and the main contact (110); The static arc contact (130) is located below the main contact plate (111) and is separated from the main contact (110) by a baffle (120) with a certain distance therebetween. The width of the static arc contact (130) is adapted to the width of the main contact plate (111). The moving contact area (211) of the grounding knife (210) contacts the side of the static arc contact (130) to form direct conduction between the moving contact assembly (200) and the static arc contact (130). The static arc contact (130) protrudes from the front end of the main contact plate (111), so that the static arc contact (130) contacts the moving contact assembly (200) before the main contact plate (111) contacts the moving contact assembly (200).

3. The grounding switch with arc striking structure and arc extinguishing structure according to claim 2, characterized in that: The lower surface of the baffle (120) is a plane, and the static arc contact (130) comprises a connecting plate (131) that fits the lower surface of the baffle (120) and is fixedly connected to the baffle (120), and an inclined plate (132) formed by extending and bending the outer end of the connecting plate (131) downward. The spacing between the inclined plate (132) and the main contact plate (111) gradually increases from the inside to the outside. The inclined plate (132) protrudes from the front end of the main contact plate (111), so that the inclined plate (132) contacts the moving contact assembly (200) before the main contact plate (111) contacts the moving contact assembly (200).

4. The grounding switch with arc striking structure and arc extinguishing structure according to claim 3, characterized in that: The spoiler (120) is a flat plate, and an embedding groove adapted to the spoiler (120) is provided below the main contact plate (111). The spoiler (120) is embedded in the embedding groove, and its thickness is greater than the embedding groove depth, so that its lower surface is raised relative to the lower surface of the main contact plate (111).

5. The grounding switch with arc striking structure and arc extinguishing structure according to claim 2, characterized in that: The movable contact assembly (200) comprises an elastic acting member (220), a connecting shaft (230), a limiting plate (240), and a spacer ring (250). The limiting plate (240) is provided with a pair and is respectively located outside two grounding knives (210). The spacer ring (250) is located between the two grounding knives (210). The connecting shaft (230) passes through the limiting plate (240), the grounding knife (210), and the spacer ring (250). The elastic acting member (220) is located outside the limiting plate (240) so as to form an inward elastic acting force on the grounding knife (210).

6. The grounding switch with arc striking structure and arc extinguishing structure according to claim 5, characterized in that: The spacer ring (250) is rollable relative to the connecting shaft (230); in a partial path of closing rotation, the spacer ring (250) abuts against the static arc contact (130) and rolls relative to the static arc contact (130).

7. The grounding switch with arc striking structure and arc extinguishing structure according to claim 5, characterized in that: The elastic action member (220) is a disc spring assembly.

8. The grounding switch with arc striking and arc extinguishing structures according to claim 1, characterized in that: The arc extinguishing chamber (400) comprises a bracket (410) and a plurality of arc extinguishing grids (420) fixed on the bracket (410); an arc striking gap is formed between the outer end of the static arc contact (130) and the plurality of arc extinguishing grids (420).

9. The grounding switch with arc striking structure and arc extinguishing structure according to claim 8, characterized in that: The bracket (410) comprises a connecting block (411) fixedly connected to the outer end of the main contact (110) and a fixing rod (412) at the outer end of the connecting block (411); the fixing rod (412) is arranged obliquely and the oblique direction tends to the rotation direction of the moving contact assembly (200); a plurality of arc extinguishing grids (420) are arranged in sequence along the oblique direction of the fixing rod (412); and the arc extinguishing grids (420) are provided with openings (421) for the moving contact assembly (200) to extend into.

10. The grounding switch with arc striking structure and arc extinguishing structure according to claim 9, characterized in that: The fixing rod (412) includes a flat connecting plate (4121) and a plurality of sequentially arranged limiting partitions (4122) at the lower end of the flat connecting plate (4121). Adjacent limiting partitions (4122) are connected by longitudinal partitions (4123) perpendicular to the flat connecting plate (4121) to form two slots. The outer peripheral surface of the limiting partition (4122) is an arc surface. A card slot (4124) is provided at each slot of the limiting partition (4122). Two inserting pieces (422) adapted to the slots are provided on one side of the arc extinguishing grid (420) away from the opening (421), and a clamping block (423) adapted to the clamping slot (4124) is provided on the inserting piece (422); the clamping block (423) cooperates with the clamping slot (4124) to secure the arc extinguishing grid (420) to the fixing rod (412) via a buckle connection; The arc extinguishing grid (420) protrudes relative to the fixing rod (412) on both sides of the two inserting pieces (422); The moving contact assembly (200) comprises a pair of mutually parallel and oppositely arranged grounding knives (210), the inner side surfaces of the grounding knives (210) being provided with a moving contact area (211), and the position of the grounding knives (210) corresponding to the position of the arc extinguishing grid (420) protruding relative to the fixing rod (412).

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