Embedded zero-flashover device

Abstract

The utility model discloses an embedded zero-flashover device, which comprises a plurality of zero-flashover modules embedded in a plurality of wiring ports of a wiring end of a circuit breaker and an outer casing fixed on the wiring end, each zero-flashover module comprises an arc-extinguishing inner casing, an arc-extinguishing assembly and an insulating partition plate, the arc-extinguishing inner casing is inserted in the wiring port, and the insulating partition plate is inserted in the arc-extinguishing assembly. The bottom of the zero-flashover module is provided with a plurality of jack structures communicated with the arc-extinguishing cavity at intervals, the arc-extinguishing assembly is inserted into the arc-extinguishing cavity through the jack structures, the insulating partition plate is inserted into the arc-extinguishing cavity and shields the jack structures, and the zero-flashover module plays roles in secondary arc extinguishing, metal particle adsorption and free gas neutralization in the wiring port of each phase. According to the zero-flashover module, the embedded installation is realized at the wiring end by utilizing the position space of the existing wiring port, so that the size of the outer casing can be reduced, the installation size of the whole zero-flashover device is reduced, the modular assembly effect is realized, and the use performance of the product is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to low voltage electrical apparatus technical field, concretely relates to a kind of embedded zero arc flash device. BACKGROUND

[0002] In the action process of plastic case circuit breaker in the action process of large current with load or fault breaking, the voltage between moving contact and static contact will cause air medium discharge, form arc, but only arc chamber in the circuit breaker cannot completely and reliably extinguish arc, residual arc will be ejected along airway to the wiring end of circuit breaker, with a large amount of hot metal particles, these metal particles directly spurt out of circuit breaker outside along arc, which can cause short circuit of surrounding line or burnout.

[0003] In order to make circuit breaker achieve zero arc flash effect, the existing method is to install zero arc flash cover at the wiring end position of circuit breaker to play the role of arc extinguishing and metal particle blocking for arc gas, for example, Chinese patent document CN219435798U discloses a zero arc flash cover for circuit breaker, which comprises a cover body and a plurality of mounting cavities spaced apart on the cover body, and a plurality of arc extinguishing assemblies arranged in the mounting cavities, respectively, each arc extinguishing assembly comprises a plurality of arc extinguishing sheets arranged in parallel and opposite in the mounting cavity, and a plurality of air holes are distributed on the arc extinguishing sheets, the bottom of the zero arc flash cover is designed as an opening, so that the arc extinguishing sheets are inserted into the mounting cavity through the slot structure from the bottom of the zero arc flash cover. As can be seen from the above structure, the installation structure of the zero arc flash cover is complex, and the bottom opening design exposes the arc extinguishing sheets, which can easily cause some arc and free gas to be ejected from the bottom, and the protection performance is poor, and the arc extinguishing effect is not ideal. The whole volume of the assembled zero arc flash cover is relatively large, which can increase the volume of circuit breaker product and reduce the space utilization. SUMMARY

[0004] Therefore, the technical problem to be solved by the utility model is to overcome the problems of complex installation structure, poor protection performance, unsatisfactory arc extinguishing effect and large volume of zero arc flash cover in the prior art.

[0005] To solve the above technical problems, the utility model provides a kind of embedded zero arc flash device, is installed in the wiring end of circuit breaker, including a plurality of zero arc flash modules embedded in a plurality of wiring ports of wiring end, and the outer shell of being fixed on wiring end and being pressed to a plurality of zero arc flash modules, the zero arc flash module includes:

[0006] Arc extinguishing inner shell is inserted in the wiring port and located above terminal, and the arc extinguishing inner shell has arc extinguishing cavity communicating with the wiring port, and a plurality of plug hole structures communicating with arc extinguishing cavity are arranged at the bottom of arc extinguishing cavity;

[0007] Arc extinguishing assembly is inserted into the arc extinguishing cavity from plug hole structure and faces the wiring port;

[0008] The insulating partition plate is inserted into the arc extinguishing chamber and shields the insertion hole structure, so that the insulating partition plate and the arc extinguishing assembly form a limiting fit to prevent the arc extinguishing assembly from being pulled out of the insertion hole structure.

[0009] In the embedded zero arc flying device, one end of the arc extinguishing chamber is an inlet end with an opening facing the wiring port, and the other end is an outlet end with a plurality of limiting strips. The insulating partition plate is horizontally inserted into the arc extinguishing chamber from the inlet end and is in contact with the inner bottom surface of the arc extinguishing inner shell.

[0010] In the embedded zero arc flying device, a plurality of insertion hole structures are arranged in the extension direction of the arc extinguishing chamber and are sequentially and spaced apart on the bottom of the arc extinguishing inner shell. The arc extinguishing assembly includes a plurality of arc extinguishing meshes arranged in the plurality of insertion hole structures. The upper ends of the plurality of arc extinguishing meshes are limited to abut against the top of the arc extinguishing inner shell, and the lower ends of the plurality of arc extinguishing meshes are limited to abut against the insulating partition plate.

[0011] In the embedded zero arc flying device, the bottom of the inlet end is provided with two limiting clamping grooves on both sides, and one end of the insulating partition plate is provided with two limiting clamping blocks clamped in the limiting clamping grooves.

[0012] In the embedded zero arc flying device, the insertion hole structure includes limiting insertion grooves extending on the inner walls on both sides of the arc extinguishing chamber, and the arc extinguishing meshes are provided with limiting convex edges correspondingly inserted into the limiting insertion grooves.

[0013] In the embedded zero arc flying device, the limiting convex edges are correspondingly formed with extrusion protrusions extruded and inserted into the limiting insertion grooves to form an interference fit.

[0014] In the embedded zero arc flying device, at least one convex rib structure is integrally stamped and formed on the arc extinguishing mesh.

[0015] In the embedded zero arc flying device, the wiring port has an operating hole vertically extending to the top of the wiring end, and the top of the arc extinguishing inner shell is provided with a positioning clamping table embedded in the operating hole. The positioning clamping table blocks the operating hole and is hung on the top of the wiring end. After the zero arc flying module is embedded, the wiring port forms an isolation area below the arc extinguishing inner shell.

[0016] In the embedded zero arc flying device, the outer shell includes a plurality of accommodation grooves surrounding and accommodating a plurality of zero arc flying modules, and a plurality of grid backstop plates are arranged on the back of the outer shell corresponding to the plurality of accommodation grooves. The grid backstop plates are abutted and pressed against one end of the arc extinguishing inner shell exposed outside the wiring port.

[0017] In the embedded zero arc flying device, the top of the wiring end is provided with a groove area including a plurality of operating holes, and the outer shell has an upper backplate matched and fixed in the groove area. The upper backplate abuts and presses against the positioning clamping table.

[0018] The technical scheme of the utility model has the following advantages compared with the prior art:

[0019] 1. In the embedded zero arc flash device, a plurality of zero arc flash modules are embedded in a plurality of wiring ports of a circuit breaker wiring terminal, and then an outer cover is installed on the wiring terminal to limit the plurality of zero arc flash modules, so as to prevent the plurality of zero arc flash modules from being knocked out of the wiring port under high air pressure. The zero arc flash module is composed of an arc extinguishing inner shell, an arc extinguishing assembly and an insulating partition plate. The zero arc flash module plays the role of secondary arc extinguishing, adsorption of metal particles and neutralization of ionized gas in each wiring port, thereby avoiding arc flash at the circuit breaker wiring terminal, achieving zero arc flash effect, and having the advantages of small size of the outer cover, small installation volume of the entire zero arc flash device, small occupied space, modular assembly, convenient installation, and improved product performance.

[0020] 2. In the embedded zero arc flash device, the arc extinguishing assembly is inserted into the arc extinguishing cavity from the insertion hole position at the bottom of the arc extinguishing inner shell, and then the insulating partition plate is inserted into the arc extinguishing cavity to block the insertion hole structure and form a limiting abutting cooperation with the arc extinguishing assembly. The advantages of this design are as follows: on the one hand, the insulating partition plate limits the arc extinguishing assembly to prevent it from falling out of the insertion hole position, thereby achieving limiting installation of the arc extinguishing assembly in the arc extinguishing cavity and avoiding exposure of the arc extinguishing mesh; on the other hand, the insertion hole structure is blocked by the insulating partition plate, which plays an insulating isolation role between the arc extinguishing cavity and the wiring port, preventing the arc and the charged ionized gas from entering the wiring port below the zero arc flash module through the insertion hole structure to cause erosion damage to the wiring terminal, ensuring that the arc extinguishing gas filtered by the arc extinguishing assembly is only discharged from the outlet end of the arc extinguishing inner shell, thereby preventing damage to the wiring terminal, busbar, etc., and achieving the purpose of zero arc flash. The zero arc flash module is modularized and embedded for independent installation, which is convenient and efficient.

[0021] 3. The embedded zero arc device, when the arc elimination mesh is inserted into the arc elimination cavity through the jack structure, the limiting convex edges on both sides of the arc elimination mesh are inserted into the limiting slot on the inner wall of the arc elimination cavity, thereby playing a positioning and installation role on the arc elimination mesh, according to the extrusion protrusion arranged on the limiting convex edge, the limiting convex edge forms an interference fit with the limiting slot through the extrusion protrusion, thereby tightly fitting and installing the arc elimination mesh in the arc elimination cavity, then the insulating partition plate is inserted into the arc elimination to block the jack position and play a limiting and anti-backoff role on the arc elimination mesh, so that the fixed installation of the arc elimination mesh in the arc elimination cavity is realized, the installation structure strength is improved, the impact resistance performance is good, the arc elimination mesh is prevented from loosening and falling off due to the impact of large air pressure, and the installation is stable and reliable.

[0022] 4. The embedded zero arc device, according to the arc elimination inner shell is hung on the wiring end of the circuit breaker through the positioning card table, thereby positioning the zero arc module in the wiring port, then fixing the outer shell to the wiring end, and tightly pressing a plurality of zero arc modules through the outer shell limiting, so that the zero arc module plays a limiting and fixing role in the wiring port to prevent the zero arc module from separating from the wiring port, the installation structure is simple, convenient to install and disassemble, easy to maintain, and the installation efficiency is improved. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the specific embodiments of the utility model or the technical solutions in the prior art, the drawings needed in the specific embodiments or the prior art description will be briefly introduced as follows.

[0024] Figure 1 The structure diagram of the embedded zero arc device provided by the utility model;

[0025] Figure 2 The installation structure diagram of the zero arc module of the utility model;

[0026] Figure 3 The cross-sectional structure diagram of the zero arc module of the utility model;

[0027] Figure 4 The structure diagram of the zero arc module of the utility model;

[0028] Figure 5 The structure diagram of the arc elimination mesh of the utility model;

[0029] Explanation of reference signs: 1, arc extinguishing inner shell; 11, arc extinguishing chamber; 12, limiting strip; 13, limiting clamping groove; 2, jack structure; 3, limiting slot; 4, arc extinguishing mesh; 41, limiting convex edge; 42, extrusion protrusion; 5, insulating partition plate; 51, limiting clamping block; 6, positioning clamping table; 7, outer shell; 71, grid back baffle; 72, upper baffle; 8, recessed area; 9, wiring port; 91, operation hole; a, arc extinguishing module; b, circuit breaker. DETAILED DESCRIPTION

[0030] The technical solutions of the present application will be described clearly and completely below in conjunction with the drawings. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0031] In the description of the present application, it should be noted that the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0032] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0033] Embodiment

[0034] The present embodiment will be described in detail below in conjunction with the drawings:

[0035] The present embodiment provides an embedded zero arc device as shown in Figures 1-5 The zero arc device is installed at the wiring end of the circuit breaker b, and includes a plurality of zero arc modules embedded in a plurality of wiring ports 9 of the wiring end, and an outer shell 7 fixed on the wiring end and pressing the plurality of zero arc modules, the zero arc module includes:

[0036] An arc extinguishing inner shell 1 is inserted into the wiring port 9 and located above the wiring terminal, the arc extinguishing inner shell has an arc extinguishing chamber 11 communicating with the wiring port 9, and a plurality of jack structures 2 communicating with the arc extinguishing chamber 11 are arranged at the bottom thereof;

[0037] An arc extinguishing assembly is inserted into the arc extinguishing chamber 11 from the jack structure 2 and faces the wiring port 9;

[0038] The insulating partition plate 5 is inserted into the arc extinguishing cavity 11 and covers the insertion hole structure 2, so that the insulating partition plate 5 and the arc extinguishing assembly form a limiting fit to prevent the arc extinguishing assembly from falling out of the insertion hole structure 2.

[0039] In the above embodiment, the plurality of zero arc flying modules are embedded in the plurality of wiring ports 9 of the circuit breaker b terminal, and then the outer shell 7 is installed on the terminal to limit the plurality of zero arc flying modules, so as to prevent the plurality of zero arc flying modules from being impacted by high air pressure and falling out of the wiring port 9. The zero arc flying module is composed of the arc extinguishing inner shell 1, the arc extinguishing assembly and the insulating partition plate 5. The zero arc flying module plays the role of secondary arc extinguishing, adsorbing metal particles and neutralizing ionized gas in each phase of the wiring port 9, avoids the arc flying phenomenon at the circuit breaker terminal, and realizes the zero arc flying effect. The advantage of the technical solution is that the zero arc flying module is embedded and installed in the terminal by using the position space of the existing wiring port. Therefore, the volume of the outer shell 7 can be small, the installation volume of the entire zero arc flying device is reduced, the installation occupies a small space, the modular assembly effect is realized, the installation is convenient and fast, and the product use performance is improved.

[0040] As can be seen from the above, the arc extinguishing assembly is inserted into the arc extinguishing cavity 11 from the insertion hole position at the bottom of the arc extinguishing inner shell 1, and then the insulating partition plate 5 is inserted into the arc extinguishing cavity 11 to cover the insertion hole structure 2 and form a limiting fit with the arc extinguishing assembly. The advantage of this design is that, on the one hand, the insulating partition plate 5 limits the arc extinguishing assembly to prevent it from falling out of the insertion hole position, thereby realizing the limiting installation of the arc extinguishing assembly in the arc extinguishing cavity 11 and avoiding the exposure of the arc extinguishing mesh 4; on the other hand, the insulating partition plate 5 covers the insertion hole structure 2 to play an insulating isolation role between the arc extinguishing cavity 11 and the wiring port 9, so as to prevent the arc and the charged ionized gas from entering the wiring port below the zero arc flying module through the insertion hole structure 2 to cause erosion damage to the terminal, ensure that the arc extinguishing filtered arc extinguishing gas is only discharged from the outlet end of the arc extinguishing inner shell 1, so as not to cause damage to the terminal, busbar and the like, thereby realizing the zero arc flying purpose. The zero arc flying module realizes modularization, embedded independent installation, convenient and fast installation, and improves the installation efficiency.

[0041] Further preferably, as shown in Figure 2 , one end of the arc extinguishing cavity 11 is an inlet end with an opening facing the wiring port 9, and the other end is an outlet end provided with a plurality of limiting strips 12. The insulating partition plate 5 is horizontally inserted into the arc extinguishing cavity 11 from the inlet end and is in contact with the inner bottom surface of the arc extinguishing inner shell 1. Two limiting clamping grooves 13 are arranged at the bottom of the inlet end. Two limiting clamping blocks 51 are arranged at the two sides of one end of the insulating partition plate 5 and are clamped in the limiting clamping grooves 13. The limiting clamping blocks 51 and the limiting clamping grooves 13 cooperate to realize the positioning and installation of the insulating partition plate 5, so as to ensure that the insulating partition plate 5 is stably and reliably installed in the arc extinguishing cavity 11.

[0042] The specific arrangement of the arc extinguishing assembly will be described in detail below. Figures 2-5 The specific arrangement of the arc extinguishing assembly will be described in detail below.

[0043] A plurality of plug hole structures 2 are arranged in the bottom of the arc extinguishing inner shell 1 in sequence along the extension direction of the arc extinguishing cavity, and the arc extinguishing assembly comprises a plurality of arc extinguishing screens 4 inserted in the plurality of plug hole structures 2. The plug hole structure 2 comprises a limiting slot 3 extending and arranged on the inner wall of the arc extinguishing cavity 11 on both sides, and the arc extinguishing screen 4 is provided with a limiting convex edge 41 corresponding to the limiting slot 3. The installation design allows the plurality of arc extinguishing screens 4 to be arranged in the arc extinguishing cavity 11 in sequence, and the upper end of the plurality of arc extinguishing screens 4 is limited to abut against the top of the arc extinguishing inner shell 1, and the lower end of the plurality of arc extinguishing screens 4 is limited to abut against the insulating partition plate 5. In this way, the arc extinguishing screen 4 can be prevented from being separated from the plug hole structure 2, so as to firmly fix the arc extinguishing screen 4 in the arc extinguishing cavity 11.

[0044] Further preferably, the limiting convex edge 41 is correspondingly formed with an extrusion protrusion 42 extruded and inserted in the limiting slot 3 to form an interference fit, as shown in Figures 4-5 In this way, when the arc extinguishing screen 4 is inserted into the arc extinguishing cavity 11 through the plug hole structure 2, the limiting convex edges 41 on both sides of the arc extinguishing screen 4 are correspondingly inserted into the limiting slots 3 on the inner walls of the arc extinguishing cavity 11 on both sides, thereby playing a positioning and installation role on the arc extinguishing screen 4. At the same time, the extrusion protrusion 42 forms an interference fit with the limiting slot 3, thereby tightly fitting and installing the arc extinguishing screen 4 in the arc extinguishing cavity 11. Then, the insulating partition plate 5 is inserted into the arc extinguishing cavity 11 to block the plug hole position and play a limiting and retreating role on the arc extinguishing screen 4. In this way, the installation and fixation of the arc extinguishing screen 4 in the arc extinguishing cavity 11 are realized, the installation structure strength is improved, the impact resistance performance is good, and the arc extinguishing screen 4 is prevented from loosening and falling due to the impact of a large gas pressure.

[0045] As shown in Figure 5 The arc extinguishing screen 4 is integrally formed with at least one convex rib structure, which can enhance the structural strength of the arc extinguishing screen 4 and better withstand the impact of gas pressure, thereby having good impact resistance.

[0046] In this embodiment, the arc extinguishing screen 4 is integrally formed with at least one convex rib structure, which can enhance the structural strength of the arc extinguishing screen 4 and better withstand the impact of gas pressure, thereby having good impact resistance. Figures 1-3As shown, the wiring port 9 has an operating hole 91 vertically extending to the top of the wiring end, and the top of the arc extinguishing inner shell 1 is provided with a positioning clamping table 6 embedded in the operating hole 91, and the positioning clamping table 6 blocks the operating hole 91 and is hung on the top of the wiring end. As known from the above, the arc extinguishing inner shell 1 is hung on the wiring end of the circuit breaker b through the positioning clamping table 6, so as to position the zero arc flying module in the wiring port 9, and then the outer cover shell 7 is fixed to the wiring end, and the plurality of zero arc flying modules are limited and compressed by the outer cover shell 7. In this way, the zero arc flying module is limited and fixed in the wiring port 9, so as to prevent the zero arc flying module from being separated from the wiring port 9. The installation structure is simple, convenient to install and disassemble, easy to maintain, and improves the installation efficiency.

[0047] As Figure 1 shown, the outer cover shell 7 includes a plurality of accommodation grooves surrounding the plurality of zero arc flying modules, a plurality of grid back plates 71 corresponding to the plurality of accommodation grooves and arranged on the back of the outer cover shell 7, and a plurality of threading holes arranged below the plurality of exhaust grid plates. The grid back plate 71 is provided with a plurality of air holes, and the gas after the zero arc flying module is processed is discharged to the outside through the plurality of air holes on the grid back plate 71. The grid back plate 71 is matched and pressed against one end of the arc extinguishing inner shell 1 exposed outside the wiring port 9, thereby limiting the installation of the arc extinguishing inner shell 1. The wiring port 9 forms an isolation area below the arc extinguishing inner shell 1 after embedding the zero arc flying module. The isolation area is provided with a wiring terminal, so that the external wiring busbar or wire extends to the isolation area through the threading hole and is connected with the wiring terminal. According to the insulation isolation between the arc extinguishing cavity 11 in the arc extinguishing inner shell 1 and the isolation area, the charged ionized gas can be prevented from flowing into the isolation area through the jack position, so as to ensure the use safety of the wiring terminal and the busbar in the isolation area.

[0048] Obviously, the above embodiments are only examples for clearly illustrating, but not limiting the embodiments. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. Here, all the embodiments need not and cannot be exhausted. The obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. An embedded zero arc flash device installed at a terminal of a circuit breaker (b) characterized by: The zero arc module comprises: An arc extinguishing inner shell (1) is inserted into the terminal and above the terminal, and has an arc extinguishing cavity (11) communicating with the terminal (9), and a plurality of insertion hole structures (2) are arranged on the bottom of the arc extinguishing cavity (11); An arc extinguishing assembly is inserted into the arc extinguishing cavity (11) through the insertion hole structure (2) and faces the terminal (9); An insulation partition plate (5) is inserted into the arc extinguishing cavity (11) and covers the insertion hole structure (2), so that the insulation partition plate (5) and the arc extinguishing assembly form a limiting fit to prevent the arc extinguishing assembly from being pulled out of the insertion hole structure (2).

2. The flush zero arc device of claim 1, wherein: One end of the arc extinguishing cavity (11) is an inlet end with an opening facing the terminal (9), and the other end is an outlet end with a plurality of limiting strips (12); the insulation partition plate (5) is horizontally inserted into the arc extinguishing cavity (11) from the inlet end and is in contact with the inner bottom surface of the arc extinguishing inner shell (1).

3. The flush zero arc embedded device according to claim 1 or 2, characterized in that: A plurality of insertion hole structures (2) are arranged on the bottom of the arc extinguishing cavity (11) in sequence along the extension direction of the arc extinguishing cavity, and the arc extinguishing assembly comprises a plurality of arc extinguishing meshes (4) inserted into the insertion hole structures (2), the upper ends of the arc extinguishing meshes (4) are limited to abut against the top of the arc extinguishing inner shell (1), and the lower ends of the arc extinguishing meshes (4) are limited to abut against the insulation partition plate (5).

4. The embedded zero arc flash device of claim 3, wherein: The insertion hole structure (2) comprises a limiting slot (3) extending on the inner wall of the arc extinguishing cavity (11), and the arc extinguishing mesh (4) is provided with a limiting protruding edge (41) corresponding to the limiting slot (3).

5. The embedded zero arc flash device of claim 4, wherein: The limiting protruding edge (41) is correspondingly formed with an extrusion protrusion (42) extruded and inserted into the limiting slot (3) to form an interference fit.

6. The embedded zero arc flash device of claim 5, wherein: At least one protruding rib structure is integrally punched and formed on the arc extinguishing mesh (4).

7. The embedded zero arc flash device of claim 2, wherein: Two limiting clamping grooves (13) are arranged on the bottom of the inlet end, and two limiting clamping blocks (51) are arranged on the two sides of one end of the insulation partition plate (5) and clamped in the limiting clamping grooves (13).

8. The embedded zero arc flash device of claim 1, wherein: The terminal (9) has an operating hole (91) extending vertically to the top of the terminal, the top of the arc extinguishing inner shell (1) is provided with a positioning clamping table (6) embedded in the operating hole (91), the positioning clamping table (6) blocks the operating hole (91) and is hung on the top of the terminal, and the terminal (9) forms an isolation area below the arc extinguishing inner shell (1) after embedding the zero arc module.

9. The embedded zero arc flash device of claim 8, wherein: The top of the terminal is provided with a groove area (8) containing a plurality of operating holes (91), and the outer shell (7) has an upper baffle (72) matched and fixed in the groove area (8), and the upper baffle (72) abuts against the positioning clamping table (6).

10. The embedded zero arc flash device of claim 1, wherein: The outer shell (7) comprises a plurality of accommodating grooves for accommodating a plurality of zero-arc modules, and a plurality of grid back baffles (71) arranged on the back of the outer shell (7) corresponding to the plurality of accommodating grooves, the grid back baffles (71) being matched to abut against one end of the arc-extinguishing inner shell (1) exposed to the terminal (9).

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