Arc extinguishing device and switching device

Abstract

The utility model discloses an arc extinguishing device and a switching electric appliance, and relates to the technical field of low-voltage electric appliances. The arc extinguishing device is arranged in the switching device, the switching device comprises a shell, a moving contact outgoing line arranged in the shell, a moving contact connected with the moving contact outgoing line, a static contact outgoing line and a static contact connected with the static contact outgoing line, and the moving contact outgoing line, the moving contact, the static contact and the static contact outgoing line jointly form a loop. And the moving contact is contacted with or separated from the static contact so as to connect or disconnect the loop. The arc-extinguishing device comprises an arc-extinguishing structure and / or an arc-extinguishing structure, the arc-extinguishing structure and / or the arc-extinguishing structure are / is located between a moving contact outgoing line and a static contact outgoing line, and the arc-extinguishing structure and / or the arc-extinguishing structure are / is located on the outer side of a rotating path of a moving contact rotating relative to a static contact. And the arc extinguishing structure and / or the arc extinguishing structure are / is used for performing arc extinguishing on an electric arc generated between the moving contact and the static contact. The arc extinguishing device and the switching device can improve the arc extinguishing capability so as to meet the high breaking requirement of a product.

Description

Technical Field

[0001] This utility model relates to the field of low-voltage electrical technology, and more specifically, to an arc-extinguishing device and a switching device. Background Art

[0002] With the rapid development of society, economy, and urban construction, people's living standards and housing conditions have significantly improved, leading to a more comprehensive understanding of electrical safety. To enhance electrical safety, switching devices, such as load switches and relays, are typically connected to electrical circuits to provide safety protection.

[0003] Load switches are switching devices that fall between circuit breakers and disconnectors, capable of interrupting rated load current and a certain overload current, but not short-circuit current. Relays are switching devices that cause a predetermined step change in the controlled quantity in the electrical output circuit when the change in the input quantity (excitation quantity) reaches a specified requirement. Existing load switches and relays lack arc-extinguishing devices, resulting in low arc-extinguishing performance and failing to meet the needs of some applications requiring high breaking capacity. Utility Model Content

[0004] The purpose of this utility model is to provide an arc extinguishing device and a switching electrical appliance that can improve the arc extinguishing capability to meet the high breaking capacity requirements of products.

[0005] The embodiments of this utility model are implemented as follows:

[0006] A first aspect of this utility model provides an arc-extinguishing device disposed within a switching device. The switching device includes a housing and a moving contact lead wire disposed within the housing, a moving contact connected to the moving contact lead wire, a stationary contact lead wire, and a stationary contact connected to the stationary contact lead wire. The moving contact lead wire, the moving contact, the stationary contact, and the stationary contact lead wire together form a circuit. The moving contact and the stationary contact contact or separate to connect or disconnect the circuit. The arc-extinguishing device includes an arc-extinguishing structure and / or an arc-suppressing structure, which is located between the moving contact lead wire and the stationary contact lead wire, and is located outside the rotation path of the moving contact relative to the stationary contact. The arc-extinguishing structure and / or the arc-suppressing structure is used to extinguish the arc generated between the moving contact and the stationary contact. This arc-extinguishing device can improve arc-extinguishing capability to meet the high breaking capacity requirements of products.

[0007] Optionally, the moving contact lead wire and the moving contact form a U-shaped structure, and the arc-extinguishing structure and / or the arc-extinguishing structure is located on the side where the opening of the U-shaped structure is located.

[0008] Optionally, the arc-extinguishing structure includes a plurality of arc-extinguishing grids, which are spaced apart.

[0009] Optionally, the arc-extinguishing structure includes a U-shaped arc-extinguishing steel sheet, the opening of which faces the moving contact.

[0010] Optionally, when the arc extinguishing device includes the arc extinguishing structure and the arc suppression structure, the arc suppression structure is located on the side of the arc extinguishing structure away from the moving contact.

[0011] Optionally, the arc-extinguishing structure includes at least one blocking member for separating the inner cavity of the housing to form an upper air passage and a lower air passage, respectively. Both the upper and lower air passages have at least one bending structure. The upper air passage corresponds to the moving contact to introduce the arc root on the moving contact into the arc-extinguishing structure, and the lower air passage corresponds to the stationary contact to introduce the arc root on the stationary contact into the arc-extinguishing structure. The upper and lower air passages converge on the side away from the moving contact to form an air outlet, and the air outlet is disposed opposite to the arc outlet on the housing.

[0012] Optionally, the blocking member has a convex, columnar, or plate-like structure; there are multiple blocking members and multiple arc outlets, and the multiple blocking members and multiple arc outlets correspond one-to-one and are stacked along the rotation axis of the moving contact.

[0013] A second aspect of this utility model provides a switching device including the aforementioned arc-extinguishing device, wherein the switching device is a load switch or a relay. This arc-extinguishing device can improve arc-extinguishing capability to meet the high breaking capacity requirements of products.

[0014] Optionally, there are multiple moving contacts, which are stacked in a direction perpendicular to the housing, and the multiple moving contacts share the same arc extinguishing device.

[0015] Optionally, the switching device further includes a current transformer, which is sleeved on the stationary contact lead-out line, and the arc extinguishing device is located above the current transformer.

[0016] The beneficial effects of this utility model embodiment include:

[0017] The arc-extinguishing device is installed inside the switchgear. The switchgear includes a housing and a moving contact lead wire, a moving contact connected to the moving contact lead wire, a stationary contact lead wire, and a stationary contact connected to the stationary contact lead wire, all housed within the housing. The moving contact lead wire, the moving contact, the stationary contact, and the stationary contact lead wire together form a circuit. The moving contact and the stationary contact come into contact or separate to connect or disconnect the circuit. The arc-extinguishing device includes an arc-extinguishing structure and / or an arc-suppressing structure, located between the moving contact lead wire and the stationary contact lead wire, and positioned outside the rotation path of the moving contact relative to the stationary contact. The arc-extinguishing structure and / or arc-suppressing structure are used to extinguish the arc generated between the moving contact and the stationary contact. This arc-extinguishing device can improve arc-extinguishing capability to meet the high breaking capacity requirements of products. Compared to existing technologies, this application not only provides an arc-extinguishing device between the moving contact lead and the stationary contact lead to improve the rationality and compactness of the layout of various components within the housing, but also positions the arc-extinguishing device to the outside of the rotation path of the moving contact relative to the stationary contact. This allows for the effective extinguishing of the arc generated between the moving and stationary contacts of the load switch, thereby improving the arc-extinguishing capability of the load switch to meet the high breaking capacity requirements of the product. Attached Figure Description

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 One of the structural schematic diagrams of the load switch provided in the embodiment of this utility model;

[0020] Figure 2 A second schematic diagram of the structure of the load switch provided in this embodiment of the utility model;

[0021] Figure 3 This is a schematic diagram of the arc-extinguishing device provided in an embodiment of the present invention;

[0022] Figure 4 This is a schematic diagram of the arc-extinguishing structure provided in an embodiment of the present invention;

[0023] Figure 5 This is a schematic diagram of the arc-extinguishing device provided in another embodiment of the present invention;

[0024] Figure 6 A schematic diagram of the arc-extinguishing device provided in another embodiment of this utility model;

[0025] Figure 7 This is a schematic diagram of the arc-extinguishing device provided in another embodiment of the present invention.

[0026] Icons: 100-Load switch; 10-Housing; 11-Arc outlet; 20-Moving contact lead-out; 30-Moving contact; 40-Stationary contact lead-out; 50-Stationary contact; 60-Arc extinguishing device; 61-Arc extinguishing structure; 611-Arc extinguishing grid; 612-Groove; 613-U-shaped arc extinguishing steel sheet; 62-Arc extinguishing structure; 621-Upper arc-drawing plate; 622-Blocking component; 623-Upper air passage; 624-Lower air passage; 70-Instrument transformer. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0028] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0029] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0030] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the utility model product is typically placed when in use. These terms are intended solely to facilitate the description of this utility model and to simplify the description, and are not intended to indicate or imply that the device or component referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on this utility model. Furthermore, the terms "first," "second," and "third," etc., are used solely to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0031] Furthermore, terms such as "horizontal" and "vertical" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," not that the structure must be completely horizontal, but can be slightly tilted.

[0032] In the description of this utility model, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0033] Please refer to the reference. Figures 1 to 7 This application provides a switching device including an arc-extinguishing device 60. The switching device is either a load switch 100 or a relay. The arc-extinguishing device 60 is used to improve the arc-extinguishing capability of the switching device to meet the high breaking capacity requirements of the product. The following explanation and accompanying drawings use a load switch 100 as an example. It should be understood that when the switching device is a relay, the same specific structure and corresponding beneficial effects will not be repeated here.

[0034] like Figure 1 As shown, the load switch 100 includes a housing 10 and a moving contact lead 20 disposed within the housing 10, a moving contact 30 connected to the moving contact lead 20, a stationary contact lead 40 connected to the stationary contact lead 40, and a stationary contact 50 connected to the stationary contact lead 40. The moving contact lead 20, the moving contact 30, the stationary contact 50, and the stationary contact lead 40 together form a circuit. The moving contact 30 contacts or separates from the stationary contact 50 to connect or disconnect the circuit, thereby ensuring the normal operation of the load switch 100.

[0035] It should be noted that both the moving contact lead 20 and the stationary contact lead 40 have terminals extending out of the housing 10, so that the load switch 100 can be connected to the distribution box and thus connected to the power circuit, thereby enabling the load switch 100 to control the power circuit accordingly.

[0036] Optionally, there are multiple moving contacts 30, which are stacked in a direction perpendicular to the housing 10. The multiple moving contacts 30 share the same arc extinguishing device 60 to reduce the space occupied by the arc extinguishing device 60 in the housing 10, thereby contributing to the miniaturization of the load switch 100.

[0037] Optionally, such as Figure 2As shown, the load switch 100 also includes a current transformer 70, which is sleeved on the stationary contact lead 40, and an arc-extinguishing device 60 is located above the current transformer 70. The current transformer 70 has two main functions: first, to expand the range of AC electrical instruments; and second, to isolate high voltage and high current and convert them into low voltage and low current, thereby protecting the electrical circuit.

[0038] Specifically, if Figure 1 and Figure 2 As shown, the arc-extinguishing device 60 is disposed inside the housing 10 of the load switch 100. The arc-extinguishing device 60 includes an arc-extinguishing structure 61 and / or an arc-extinguishing structure 62. The arc-extinguishing structure 61 and / or the arc-extinguishing structure 62 are located between the moving contact lead-out line 20 and the stationary contact lead-out line 40 to improve the rationality and compactness of the layout of various components inside the housing 10. The arc-extinguishing structure 61 and / or the arc-extinguishing structure 62 are located outside the rotation path of the moving contact 30 relative to the stationary contact 50, so as to extinguish the arc generated between the moving contact 30 and the stationary contact 50 through the arc-extinguishing structure 61 and / or the arc-extinguishing structure 62, thereby improving the arc-extinguishing capability of the load switch 100 to meet the high breaking capacity requirements of the product.

[0039] When the moving contact 30 rotates toward the side closer to the stationary contact 50, the moving contact 30 can make contact with the stationary contact 50, thereby connecting the circuit. At this time, the load switch 100 is in the closed state. When the moving contact 30 rotates toward the side away from the stationary contact 50, the moving contact 30 can separate from the stationary contact 50, thereby disconnecting the circuit. At this time, the load switch 100 is in the open state.

[0040] During the opening and closing switching process of the load switch 100, the moving contact 30 rotates relative to the stationary contact 50 with its installation center as the rotation center and its own length as the rotation radius. An electric arc is generated between the moving contact 30 and the stationary contact 50. In order to effectively extinguish the electric arc, this application sets the arc extinguishing structure 61 and / or the arc extinguishing structure 62 on the outside of the rotation path of the moving contact 30 relative to the stationary contact 50. Here, the outside refers to the side of the rotation path away from the rotation center.

[0041] Compared to the load switch 100 in the prior art, the load switch 100 provided in this application not only has an arc extinguishing device 60 between the moving contact lead 20 and the stationary contact lead 40, but also positions the arc extinguishing device 60 towards the outside of the rotation path of the moving contact 30 relative to the stationary contact 50, so as to extinguish the arc generated between the moving contact 30 and the stationary contact 50 of the load switch 100 through the arc extinguishing device 60, thereby improving the arc extinguishing capability of the load switch 100 to meet the high breaking capacity requirements of the product.

[0042] For example, in this embodiment, the moving contact lead 20 and the moving contact 30 form a U-shaped structure or a near-U-shaped structure, and the arc extinguishing structure 61 and / or the arc extinguishing structure 62 are located on the side where the opening of the U-shaped structure or the near-U-shaped structure is located, so as to improve the rationality and compactness of the layout of various components in the housing 10.

[0043] Specifically, if Figure 3 and Figure 4 As shown, in some embodiments, the arc-extinguishing structure 61 includes multiple arc-extinguishing grids 611, which are spaced apart to cut the electric arc, thereby extinguishing the arc quickly. Further, each arc-extinguishing grid 611 has at least one groove 612, with the sidewalls of the groove 612 extending towards the moving contact 30. The electric arc is a high-temperature plasma, which is charged. Due to the law of electromagnetic induction, the arc has its own induced magnetic field. Under this induced magnetic field, the arc experiences opposite and equal forces in the left and right directions, with a total force of zero. When the arc encounters the arc-extinguishing grid 611, the magnetic lines of force on the side of the arc closest to the grid 611 are twisted, passing directly through the arc-extinguishing grid 611 with lower magnetic resistance. The groove 612 makes the magnetic line density on the side closest to the groove 612 sparse, resulting in different forces on both sides of the arc, thus generating a blowing force that causes the arc to move into the arc-extinguishing structure 61.

[0044] Of course, if Figure 5 As shown, in some other embodiments, the arc-extinguishing structure 61 may further include a single U-shaped arc-extinguishing steel sheet 613, with the opening of the U-shaped arc-extinguishing steel sheet 613 facing the moving contact 30 to facilitate the introduction of an electric arc into the arc-extinguishing structure 61. The U-shaped arc-extinguishing steel sheet 613 may be made of magnet steel.

[0045] like Figures 1 to 3 , Figures 5 to 7 As shown, when the arc extinguishing device 60 includes an arc extinguishing structure 61 and an arc extinguishing structure 62, the arc extinguishing structure 62 is located behind the arc extinguishing structure 61, that is, on the side of the arc extinguishing structure 61 away from the moving contact 30, so that the hot fluid generated when the electric arc comes out of the arc extinguishing structure 61 re-enters the arc extinguishing structure 62 and is slowed down and cooled under the action of the arc extinguishing structure 62.

[0046] Specifically, if Figure 3 and Figure 4 As shown, an upper arc-drawing plate 621 is provided inside the housing 10. The upper arc-drawing plate 621 extends from the side where the moving contact 30 is located toward the arc-extinguishing structure 62, so that the arc root on the moving contact 30 can be transferred to the arc-extinguishing structure 62 via the upper arc-drawing plate 621. For example, the cross-sectional shape of the upper arc-drawing plate 621 can be a polyline composed of multiple straight lines and / or curves.

[0047] In some embodiments, when the arc extinguishing device 60 includes an arc extinguishing structure 62, the arc extinguishing structure 62 includes at least one blocking member 622. The blocking member 622 is used to separate the inner cavity of the housing 10 to form an upper air passage 623 and a lower air passage 624, respectively. Both the upper air passage 623 and the lower air passage 624 have at least one bent structure. The upper air passage 623 corresponds to the moving contact 30 so as to quickly introduce the arc root on the moving contact 30 into the arc extinguishing structure 62 under the action of air blowing. The lower air passage 624 corresponds to the stationary contact 50 so as to quickly introduce the arc root on the stationary contact 50 into the arc extinguishing structure 62 under the action of air blowing. The upper air passage 623 and the lower air passage 624 converge on the side away from the moving contact 30 to form an air outlet. The air outlet is disposed opposite to the arc outlet 11 on the housing 10, so that the arc can be led out of the housing 10 through the air outlet and the arc outlet 11.

[0048] In other embodiments, Figure 3 , Figures 5 to 7 As shown, when the arc-extinguishing device 60 includes an arc-extinguishing structure 61 and an arc-suppressing structure 62, the arc-suppressing structure 62 includes at least one blocking member 622. The blocking member 622 is used to separate the inner cavity of the housing 10 to form an upper air passage 623 and a lower air passage 624, respectively. Both the upper air passage 623 and the lower air passage 624 have at least one bent structure. The upper air passage 623 corresponds to the moving contact 30, so that under the action of air blowing, the arc root on the moving contact 30 can be quickly introduced into the arc-extinguishing structure 61, and then passed through the arc-extinguishing structure. After passing through the arc extinguishing structure 61, the arc root on the stationary contact 50 is quickly introduced into the arc extinguishing structure 61 under the action of air blowing. After passing through the arc extinguishing structure 61, the arc root is introduced into the arc extinguishing structure 62. The upper air passage 623 and the lower air passage 624 converge on the side away from the moving contact 30 to form an air outlet. The air outlet is opposite to the arc outlet 11 on the housing 10, so that the arc can be led out of the housing 10 through the air outlet and the arc outlet 11.

[0049] The blocking element 622 can be made of non-metallic materials such as plastic. It blocks the flow of hot fluid, thus reducing its velocity and cooling it. Those skilled in the art should be able to make reasonable selections and designs for the specific structure of the blocking element 622 based on actual conditions; no specific limitations are imposed here. For example, such as… Figure 3 and Figure 5 As shown, in some embodiments, the blocking member 622 has a U-shaped or approximately U-shaped structure so that the upper air passage 623 and the lower air passage 624 converge on the side away from the moving contact 30 to form an air outlet; such as Figure 6 As shown, in some other embodiments, the baffle 622 can also be a columnar structure, in which case multiple baffles 622 are staggered, which can better play a flow-around role when the hot fluid passes through; such as Figure 7As shown, in some other embodiments, the blocking member 622 may also be plate-shaped. In this case, the blocking member 622 may be inclined to block the hot fluid coming out of the arc-extinguishing structure 61, thereby better achieving the deceleration effect.

[0050] Optionally, there may be multiple blocking elements 622 and arc outlets 11. These multiple blocking elements 622 and arc outlets 11 are arranged in a one-to-one correspondence and are stacked along the rotation axis of the moving contact 30, thus corresponding to multiple moving contacts 30 and improving the arc-extinguishing efficiency of the arc-extinguishing device 60. The actual number of blocking elements 622 and arc outlets 11 should be designed to not affect the thickness of the housing 10 of the load switch 100.

[0051] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

[0052] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable way without contradiction. In order to avoid unnecessary repetition, this utility model will not describe the various possible combinations separately.

Claims

1. An arc extinguishing device, arranged in a switch electrical appliance, the switch electrical appliance comprising a housing (10) and a moving contact lead wire (20) arranged in the housing (10), a moving contact (30) connected to the moving contact lead wire (20), a stationary contact lead wire (40) and a stationary contact (50) connected to the stationary contact lead wire (40), the moving contact lead wire (20), the moving contact (30), the stationary contact (50) and the stationary contact lead wire (40) together forming a circuit, the moving contact (30) and the stationary contact (50) contact or separate to connect or disconnect the circuit, characterized in that: The arc extinguishing device (60) comprises an arc extinguishing structure (61) and / or an arc extinguishing structure (62), wherein the arc extinguishing structure (61) and / or the arc extinguishing structure (62) are located between the moving contact lead wire (20) and the stationary contact lead wire (40), and the arc extinguishing structure (61) and / or the arc extinguishing structure (62) are located outside the rotation path of the moving contact (30) relative to the stationary contact (50), and the arc extinguishing structure (61) and / or the arc extinguishing structure (62) are used to extinguish the arc generated between the moving contact (30) and the stationary contact (50).

2. The arc extinguishing device according to claim 1, characterized in that: The moving contact lead wire (20) and the moving contact (30) form a U-shaped structure, and the arc extinguishing structure (61) and / or the arc extinguishing structure (62) are located on one side of the opening of the U-shaped structure.

3. The arc extinguishing device according to claim 1 or 2, characterized in that: The arc extinguishing structure (61) comprises a plurality of arc extinguishing grids (611), and the plurality of arc extinguishing grids (611) are arranged at intervals.

4. The arc extinguishing device according to claim 1 or 2, characterized in that: The arc extinguishing structure (61) comprises a U-shaped arc extinguishing steel sheet (613), wherein an opening of the U-shaped arc extinguishing steel sheet (613) faces the moving contact (30).

5. The arc extinguishing device according to claim 1, characterized in that: When the arc extinguishing device (60) comprises the arc extinguishing structure (61) and the arc extinguishing structure (62), the arc extinguishing structure (62) is located on a side of the arc extinguishing structure (61) away from the moving contact (30).

6. The arc extinguishing device according to claim 1 or 5, characterized in that: The arc extinguishing structure (62) includes at least one blocking member (622), and the blocking member (622) is used to separate the inner cavity of the shell (10) to form an upper air duct (623) and a lower air duct (624), respectively. The upper air duct (623) and the lower air duct (624) each have at least one bending structure. The upper air duct (623) corresponds to the moving contact (30) to introduce the arc root on the moving contact (30) into the arc extinguishing structure (62), and the lower air duct (624) corresponds to the static contact (50) to introduce the arc root on the static contact (50) into the arc extinguishing structure (62). The upper air duct (623) and the lower air duct (624) converge on a side away from the moving contact (30) to form an air outlet, and the air outlet is arranged opposite to the arc outlet (11) on the shell (10).

7. The arc extinguishing device according to claim 6, characterized in that: The blocking member (622) is in a convex structure, a columnar structure or a plate-like structure; the blocking member (622) and the arc outlet (11) are multiple in number, and the multiple blocking members (622) and the multiple arc outlets (11) correspond to each other one by one and are stacked along the rotation axis direction of the moving contact (30).

8. A switch electrical appliance, characterized in that: It comprises the arc extinguishing device (60) as claimed in any one of claims 1 to 7, wherein the switching device is a load switch (100) or a relay.

9. The switch device according to claim 8, characterized in that: There are a plurality of movable contacts (30), and the plurality of movable contacts (30) are stacked in a direction perpendicular to the housing (10), and the plurality of movable contacts (30) share the same arc extinguishing device (60).

10. The switch device according to claim 8, characterized in that: The switch electrical device also includes a mutual inductor (70), the mutual inductor (70) being sleeved on the static contact lead wire (40), and the arc extinguishing device (60) being located above the mutual inductor (70).

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