Lightning current false tripping prevention structure of circuit breaker

Abstract

The utility model discloses a lightning current false tripping prevention structure of a circuit breaker, which comprises a shell, a moving contact, a jump pin and a contact supporting piece, the moving contact, the jump pin and the contact supporting piece are arranged in the shell, the lightning current false tripping prevention structure comprises an adjusting piece, a lock catch, a spring and a shaft, the shaft is arranged in the shell, and the contact supporting piece, the lock catch and the adjusting piece are all rotatably connected on the shaft. The adjusting sheet and the lock catch are arranged in the contact supporting piece and coaxially rotate with the same rotation center, a first limiting mechanism is further arranged between the adjusting sheet and the lock catch, a second limiting mechanism is arranged between the lock catch and the jump pin, the spring is arranged in a shaft penetrating through the adjusting sheet in a sleeved mode, and the two ends of the spring are in contact connection with the lock catch and the contact supporting piece respectively and used for providing reset force for the lock catch. By adopting the false tripping structure provided by the utility model, the spring for providing the reset force for the lock catch is utilized, the false tripping action caused by the instant Lorentz force is prevented, and the false tripping structure is simple in overall structure, convenient to install and control, high in practicability and suitable for popularization and application.

Description

Technical Field

[0001] The utility model relates to the technical field of miniature circuit breakers, and particularly relates to a lightning strike current mis-tripping prevention structure for a circuit breaker. Background Art

[0002] With the rapid development of the modern social power system, the low-voltage circuit breaker, as an important part of the power system protection device, is widely used in various power users such as industry, commerce and households. The low-voltage circuit breaker is mainly used for overload, short-circuit and leakage protection of lines and equipment in the power system to ensure the safe operation of the power system. However, with the frequent occurrence of lightning weather, the influence of lightning strike current on low-voltage electrical appliances, especially miniature circuit breakers, has become increasingly prominent.

[0003] Lightning is a magnificent and somewhat awe-inspiring discharge phenomenon accompanied by lightning and thunder. The condition for generating lightning is that the thundercloud accumulates and forms polarity. Lightning strike current is a high-energy and high-voltage transient current, which is easy to be introduced into low-voltage electrical appliances through power lines, resulting in mis-tripping of the electrical appliances, and further leading to abnormal power failure of the power system, seriously affecting the stability of the power system and the normal power consumption needs of users. Most of the current low-voltage circuit breakers on the market mainly focus on conventional overload and short-circuit protection in design, but lack effective protection measures for the mis-tripping phenomenon caused by lightning strike current, and cannot well solve the problem of mis-operation of the circuit breaker caused by lightning strike current.

[0004] Therefore, in order to avoid the problem of mis-operation of the circuit breaker caused by lightning strike current, developing a low-voltage circuit breaker structure with the function of preventing lightning strike current mis-tripping has become an urgent need to improve the reliability of the power system and the safety of user power consumption. By introducing a special lightning strike current mis-tripping prevention structure into the existing miniature circuit breaker, it can not only effectively prevent the mis-tripping phenomenon caused by lightning strike current, but also ensure the normal operation of the power system in the lightning environment, which has important practical value and market prospects. Summary of the Utility Model

[0005] The technical problem to be solved by the utility model is to provide a mis-tripping prevention structure with simple structure and convenient operation for the problems existing in the background art, so as to improve the reliability of the power system and the safety of user power consumption. By using this mis-tripping prevention structure, it can not only effectively prevent the mis-tripping phenomenon caused by lightning strike current, but also ensure the normal operation of the power system in the lightning environment. Specifically, it is a lightning strike current mis-tripping prevention structure for a circuit breaker.

[0006] To solve the above technical problems, the technical solution adopted by the present utility model is as follows: A lightning strike current mis-tripping structure for a circuit breaker, comprising a housing, and a moving contact, a tripping latch and a contact support member installed in the housing. The moving contact is connected to the lower side of the contact support member by a pin, and the tripping latch is connected to the upper side of the contact support member by a pin. The lightning strike current mis-tripping structure includes an adjusting piece, a locking latch, a spring and a shaft. The shaft is installed in the housing. The contact support member, the locking latch and the adjusting piece are all rotatably connected to the shaft and rotate coaxially about a common rotation center. A first limiting mechanism is further provided between the adjusting piece and the locking latch, and a second limiting mechanism is provided between the locking latch and the tripping latch. The spring is sleeved on the shaft passing through the adjusting piece, and the two ends of the spring are respectively in contact connection with the locking latch and the contact support member, for providing a reset force to the locking latch.

[0007] Further, for a lightning strike current mis-tripping structure for a circuit breaker according to the present utility model, the locking latch is provided with a cylindrical pin corresponding to the shaft, and the locking latch is arranged on the tripping latch and is rotatably connected to the shaft through the cylindrical pin; the adjusting piece is arranged in a circular arc disk-shaped structure, and a central hole corresponding to the cylindrical pin is provided in the center of the adjusting piece. The adjusting piece installed on the locking latch is connected to the cylindrical pin through the central hole; and the spring located on the adjusting piece is connected to the cylindrical pin. Limiting members in contact with the spring are respectively provided on the locking latch and the contact support member, and the two ends of the spring are respectively in contact connection with the locking latch and the contact support member through the limiting members.

[0008] Further, for a lightning strike current mis-tripping structure for a circuit breaker according to the present utility model, the first limiting mechanism includes a limiting post provided on the locking latch, and a limiting groove provided on the adjusting piece and matching with the limiting post. The limiting post is rotationally limited through the limiting groove, so that there is no freedom degree between the locking latch and the adjusting piece, and relative movement between the locking latch and the adjusting piece is realized.

[0009] Further, for a lightning strike current mis-tripping structure for a circuit breaker according to the present utility model, the adjusting piece is arranged in a semi-circular disk-shaped structure, a tempering groove is provided on the adjusting piece, and a limiting groove is further provided on the adjusting piece. The limiting member in the locking latch passes upward through the limiting groove and extends upward above the adjusting piece; the spring is a torsion spring, one end of the torsion spring is in contact connection with the limiting member extending above the adjusting piece, and the other end is in contact connection with the limiting member provided on the contact support member.

[0010] Furthermore, a lightning strike current mis - tripping prevention structure of a circuit breaker according to the present utility model is adopted. The quenching and tempering groove is arranged outside the limiting groove, and the quenching and tempering groove is used to adjust the centroid position of the adjusting piece. By adjusting the centroid position of the adjusting piece to correspond to the centroid position of the locking catch, the centroid positions of the locking catch and the adjusting piece are made to approach their rotation center positions; and a quenching and tempering avoidance hole is also provided on the adjusting piece, and the quenching and tempering avoidance hole is located on the adjusting piece on the side away from the limiting groove.

[0011] Furthermore, a lightning strike current mis - tripping prevention structure of a circuit breaker according to the present utility model is adopted. The second limiting mechanism includes a catch lapping surface provided on the locking catch and a tripping catch lapping surface provided on the tripping catch. The locking catch and the tripping catch are in contact with or separated from each other through the catch lapping surface and the tripping catch lapping surface to achieve the normal closing or tripping state of the circuit breaker; under the action of the spring, the locking catch controls the mis - tripping action caused by the instantaneous Lorentz force between the catch lapping surface and the tripping catch lapping surface.

[0012] Adopting a lightning strike current mis - tripping prevention structure of a circuit breaker according to the present utility model, by using a shaft installed in the housing, when the switch is in the closed state: the moving contact, the adjusting piece, the locking catch, the tripping catch, the spring and the contact support are taken as a whole and can rotate counter - clockwise around the shaft to the closing position. When an abnormal current is received in the main circuit of the switch, that is, when a lightning strike current is received in the main circuit of the switch, triggering short - circuit protection or overload protection, the internal release of the circuit breaker will drive the locking catch to rotate clockwise around the shaft. When the locking catch rotates a certain angle, the catch lapping surface and the tripping catch lapping surface will be separated, and the circuit breaker trips to achieve the normal protection function. Because the existence time of the lightning strike current is short, under the action of the spring, the problem of mis - tripping caused by a large moment of inertia is eliminated.

[0013] Thus, it can be seen that by adopting the mis - tripping prevention structure of the present utility model, since a first limiting mechanism is provided between the adjusting piece and the locking catch, a second limiting mechanism is provided between the locking catch and the tripping catch, and a spring that rotates coaxially is provided on the adjusting piece. Under the action of the spring, a reset force is provided for the locking catch to control the mis - tripping action caused by the instantaneous Lorentz force between the catch lapping surface and the tripping catch lapping surface. Its overall structure is simple, convenient for installation and control, has high practicability, and is suitable for popularization and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The present utility model will be further described in detail below with reference to the accompanying drawings.

[0015] Figure 1 is the structural schematic of the present utility model Figure 1 ;

[0016] Figure 2 is the structural schematic of the present utility model Figure 2;

[0017] Figure 3 It is a schematic structural diagram after the adjusting piece and the lock catch in the present utility model are assembled;

[0018] Figure 4 It is a schematic structural diagram of the adjusting piece in the present utility model.

[0019] As shown in the figure: 1 - housing, 2 - moving contact, 3 - adjusting piece, 3a - limiting groove, 3b - central hole, 3c - quenching and tempering groove, 3d - limiting groove, 3e - quenching and tempering avoiding hole, 4 - lock catch, 4a - lock catch lapping surface, 4b - limiting post, 4c - cylindrical pin, 5 - toggle latch, 5a - toggle latch lapping surface, 6 - spring, 7 - contact support, 8 - shaft. Specific embodiments

[0020] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described in conjunction with the embodiments in the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. Based on the embodiments in the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present utility model. Embodiment 1

[0021] As Figures 1 to 4 shown, this embodiment provides a lightning strike current mis - tripping prevention structure for a circuit breaker, including a housing 1, a moving contact 2, a toggle latch 5 and a contact support 7 installed in the housing 1. The moving contact 2 is connected to the lower side of the contact support 7 through a pin, and the toggle latch 5 is connected to the upper side of the contact support 7 through a pin. The lightning strike current mis - tripping prevention structure includes an adjusting piece 3, a lock catch 4, a spring 6 and a shaft 8. The shaft 8 is installed in the housing 1. The contact support 7, the lock catch 4 and the adjusting piece 3 are all rotatably connected to the shaft 8 and rotate coaxially around a common rotation center. A first limiting mechanism is also provided between the adjusting piece 3 and the lock catch 4, and a second limiting mechanism is provided between the lock catch 4 and the toggle latch 5. The spring 6 is sleeved on the shaft 8 passing through the adjusting piece 3, and both ends of the spring 6 are in contact connection with the lock catch 4 and the contact support 7 respectively, for providing a reset force to the lock catch 4.

[0022] Furthermore, a lightning strike current mis-tripping structure of a circuit breaker according to this embodiment is adopted. The latch 4 is provided with a cylindrical pin 4c corresponding to the shaft 8. The latch 4 is arranged on the tripping latch 5 and is rotationally connected to the shaft 8 through the cylindrical pin 4c. The adjusting piece 3 is arranged in a circular arc disc shape. A central hole 3b corresponding to the cylindrical pin 4c is provided in the center of the adjusting piece 3. The adjusting piece 3 installed on the latch 4 is connected to the cylindrical pin 4c through the central hole 3b. The spring 6 located on the adjusting piece 3 is connected to the cylindrical pin 4c. Limiting members in contact with the spring 6 are respectively provided on the latch 4 and the contact support 7. Both ends of the spring 6 are respectively in contact connection with the latch 4 and the contact support 7 through the limiting members.

[0023] Furthermore, a lightning strike current mis-tripping structure of a circuit breaker according to this embodiment is adopted. The first limiting mechanism includes a limiting post 4b arranged on the latch 4 and a limiting groove 3a arranged on the adjusting piece 3 and matching with the limiting post 4b. The limiting post 4b is rotationally limited through the limiting groove 3a, so that there is no freedom degree between the latch 4 and the adjusting piece 3, and relative movement between the latch 4 and the adjusting piece 3 is realized.

[0024] Furthermore, a lightning strike current mis-tripping structure of a circuit breaker according to this embodiment is adopted. The adjusting piece 3 is arranged in a semi-circular disc shape. A quenching and tempering groove 3c is provided on the adjusting piece 3, and a limiting groove 3d is also provided on the adjusting piece 3. The limiting member in the latch 4 passes upward through the limiting groove 3d and extends upward above the adjusting piece 3. The spring 6 is a torsion spring. One end of the torsion spring is in contact connection with the limiting member extending above the adjusting piece 3, and the other end is in contact connection with the limiting member arranged on the contact support 7.

[0025] Furthermore, a lightning strike current mis-tripping structure of a circuit breaker according to this embodiment is adopted. The first limiting mechanism includes a limiting post 4b arranged on the latch 4 and a limiting groove 3a arranged on the adjusting piece 3 and matching with the limiting post 4b. The limiting post 4b is rotationally limited through the limiting groove 3a, so that there is no freedom degree between the latch 4 and the adjusting piece 3, and relative movement between the latch 4 and the adjusting piece 3 is realized. The second limiting mechanism includes a latch overlapping surface 4a arranged on the latch 4 and a tripping latch overlapping surface 5a arranged on the tripping latch 5. The latch 4 and the tripping latch 5 are in contact or separated through the latch overlapping surface 4a and the tripping latch overlapping surface 5a, so as to realize the normal closing or tripping state of the circuit breaker. Under the action of the spring 6, the latch 4 controls the mis-tripping action caused by the instantaneous Lorentz force between the latch overlapping surface 4a and the tripping latch overlapping surface 5a. Embodiment 2

[0026] Based on Embodiment 1, in this embodiment, in order to conveniently control the centroid position of the adjusting piece 3 and the centroid position of the latch 4 to correspond to their rotation center positions, thereby reducing the rotational inertia generated by the latch 4 due to the instantaneous Lorentz force received by the contact system and causing misoperation of the latch. The adjusting piece 3 is arranged in a semi-circular disc structure. A quenching and tempering groove 3c is provided on the adjusting piece 3, and a limiting groove 3d is also provided on the adjusting piece 3. The limiting piece in the latch 4 passes upward through the limiting groove 3d and extends upward above the adjusting piece 3; the spring 6 is a torsion spring. One end of the spring 6 is in contact connection with the limiting piece extending above the adjusting piece 3, and the other end is in contact connection with the limiting piece arranged on the contact support 7; in the specific manufacturing process, the quenching and tempering groove 3c is arranged outside the limiting groove 3a. The quenching and tempering groove 3c is used to adjust the centroid position of the adjusting piece 3. By adjusting the centroid position of the adjusting piece 3 to correspond to the centroid position of the latch 4, the centroid positions of the latch 4 and the adjusting piece 3 are made to approach their rotation center positions; and a quenching and tempering avoidance hole 3e is also provided on the adjusting piece 3. The quenching and tempering avoidance hole 3e is located on the adjusting piece 3 on the side far from the limiting groove 3a.

[0027] For a lightning protection current mis-tripping structure of a circuit breaker according to the present utility model, since the moving contact 2 installed in the housing 1 is connected to the contact support 7 by a pin, and the trip latch 5 is also connected to the contact support 7 by a pin, the contact support 7 and the latch 4 are simultaneously connected to the shaft 8 and share a rotation center, so that the moving contact 2, the adjusting piece 3, the latch 4, the trip latch 5, the spring 6 and the contact support 7 form an integral structure; in addition, since the adjusting piece 3 and the latch 4 are connected by a central hole 3b and a cylindrical pin 4c, and the rotation of the adjusting piece 3 is limited by the limiting groove 3a and the limiting post 4b, there is no degree of freedom between the latch 4 and the adjusting piece 3, and relative movement between the two parts of the latch 4 and the adjusting piece 3 is realized.

[0028] For a lightning protection current mis-tripping structure of a circuit breaker according to the present utility model, its working principle is as follows: As Figure 1 shown, when the switch is closed: the moving contact 2, the adjusting piece 3, the latch 4, the trip latch 5, the spring 6 and the contact support 7 are an integral whole and rotate counterclockwise around the shaft 8 in the housing 1 to the closed position. During this process, there is no relative movement between the moving contact 2, the adjusting piece 3, the latch 4, the trip latch 5, the spring 6 and the contact support 7; when the main circuit of the switch receives an abnormal current to trigger short-circuit protection or overload protection, the internal release of the circuit breaker will drive the latch 4 to rotate clockwise around the shaft 8. During this process, when the latch 4 rotates clockwise, it will drive the adjusting piece 3 to rotate clockwise together. When the latch 4 rotates a certain angle, the latch latching surface 4a and the trip latch latching surface 5a will disengage, and the circuit breaker trips, and the protection function is normal; as Figure 2As shown: When the main switch circuit receives a lightning strike current, due to the large value (usually above 10 kA) and short time (within about 20 μs) of the lightning strike current, the overload and instantaneous release inside the circuit breaker are too late to act. However, due to the large electric repulsive force (Lorentz force) between the contacts, the moving contact 2 will receive an instantaneous electric repulsive force, resulting in an instantaneous torque that causes the entire assembly of the moving contact 2, adjusting piece 3, locking catch 4, tripping catch 5, spring 6, and contact support 7 to rotate clockwise around the axis 8. Due to the dead point setting in its internal mechanism, the contact support 7 and the tripping catch 5 are restricted. However, due to functional limitations, the locking catch 4 is usually a semi-circular structure, resulting in its center of mass deviating from its rotation center. Under the action of the instantaneous torque, the locking catch 4 will receive a clockwise moment of inertia around the axis 8, and this moment of inertia will overcome the acting force of the spring 6. The spring 6 is a torsion spring. Additionally, as Figure 3 and Figure 4 shown, there are a limit groove 3d and a quenched and tempered groove 3c provided on the adjusting piece 3. The limiting member in the locking catch 4 passes upward through the limit groove 3d and extends upward above the adjusting piece 3 and is in contact connection with one end of the spring 6, so that the overall center of mass of the adjusting piece 3 also deviates from its rotation center. By cooperating the adjusting piece 3 with the locking catch 4, the overall center of mass position is located at the rotation center. Under the action of the torsion spring, when the locking catch 4 receives the instantaneous Lorentz force between the contacts, the moment of inertia received by the locking catch 4 is very small, and the locking catch 4 can withstand this impact, thus preventing misoperation.

[0029] It can be seen that by cooperating the adjusting piece 3 with the latch 4, it is used to adjust the centroid position of the whole of the latch 4 and the adjusting piece 3, so as to reduce the moment of inertia generated by the latch due to the instantaneous Lorentz force received by the contact system, and cause misoperation of the latch. At the same time, a central hole 3b matching the cylindrical pin 4c is provided in the adjusting piece 3, so that it can keep the same rotation center as the latch 4, so that the adjusting piece 3 and the latch 4 are simultaneously connected to the shaft 8. And the rotation of the limit post 4b is limited by the limit groove 3a, so that there is no degree of freedom between the latch 4 and the adjusting piece 3, and relative movement between the latch 4 and the adjusting piece 3 is realized. In addition, since a quenching and tempering groove 3c is provided in the adjusting piece 3, the quenching and tempering groove 3c is used to adjust the centroid position of the adjusting piece 3. By adjusting the centroid position of the adjusting piece 3, the centroid position of the whole of the latch 4 and the adjusting piece 3 is adjusted, so that its centroid position is as close as possible to the rotation center. In addition, by arranging the spring 6 on the adjusting piece 3, the spring 6 provides a reset force for the latch 4. When closing normally and the main circuit is overloaded or short-circuited, the latch 4 will rotate clockwise, and the latch overlapping surface 4a and the trip overlapping surface 5a will be separated, and the circuit breaker will trip, and the protection function will operate normally. When the contact system vibrates due to the instantaneous Lorentz force, the centroid lever arms of the latch 4 and the adjusting piece 3 are very small, and their moments of inertia are very small. Because the lightning strike current exists for a short time, the problem of mis-tripping caused by a large moment of inertia can be eliminated.

[0030] In summary, adopting the mis-tripping structure of the present utility model, since a first limiting mechanism is provided between the adjusting piece 3 and the latch 4, and a second limiting mechanism is provided between the latch 4 and the trip 5, and a coaxially rotating spring 6 is provided on the adjusting piece 3. Under the action of the spring 6, it is used to provide a reset force for the latch 4 to control the mis-tripping action caused by the instantaneous Lorentz force between the latch overlapping surface 4a and the trip overlapping surface 5a. Its overall structure is simple, convenient for installation and control, has high practicability, and is suitable for popularization and application.

[0031] Other details not elaborated in the present utility model are all conventional technologies well known to those skilled in the art, so no detailed description is made.

[0032] The protection scope of the present utility model is not limited to the technical solutions disclosed in the specific embodiments. The above are only the preferred embodiments of the present utility model and do not limit the present utility model. Any minor modifications, equivalent replacements and improvements made according to the technical solutions of the present utility model should be included in the protection scope of the technical solutions of the present utility model.

Claims

1. A lightning strike current mis-tripping structure for a circuit breaker, comprising a housing (1), a moving contact (2), a tripping latch (5) and a contact support (7) installed in the housing (1). The moving contact (2) is connected to the lower side of the contact support (7) by a pin, and the tripping latch (5) is connected to the upper side of the contact support (7) by a pin. It is characterized in that: The lightning protection current mis-tripping structure includes an adjusting piece (3), a locking latch (4), a spring (6) and a shaft (8). The shaft (8) is installed in the housing (1). The contact support (7), the locking latch (4) and the adjusting piece (3) are all rotatably connected to the shaft (8) and rotate coaxially about the common rotation center. A first limiting mechanism is further provided between the adjusting piece (3) and the locking latch (4), and a second limiting mechanism is provided between the locking latch (4) and the tripping latch (5). The spring (6) is sleeved on the shaft (8) passing through the adjusting piece (3), and the two ends of the spring (6) are respectively in contact connection with the locking latch (4) and the contact support (7) for providing a reset force to the locking latch (4).

2. The lightning strike current mis - tripping structure of a circuit breaker according to claim 1, wherein: The locking latch (4) is provided with a cylindrical pin (4c) corresponding to the shaft (8). The locking latch (4) is arranged on the tripping latch (5) and is rotatably connected to the shaft (8) through the cylindrical pin (4c). The adjusting piece (3) is arranged in a circular arc disk structure. A central hole (3b) corresponding to the cylindrical pin (4c) is provided in the center of the adjusting piece (3). The adjusting piece (3) installed on the locking latch (4) is connected to the cylindrical pin (4c) through the central hole (3b). The spring (6) located on the adjusting piece (3) is connected to the cylindrical pin (4c). Limiting members in contact with the spring (6) are respectively provided on the locking latch (4) and the contact support (7), and the two ends of the spring (6) are respectively in contact connection with the locking latch (4) and the contact support (7) through the limiting members.

3. The lightning strike current mis-tripping structure of a circuit breaker according to claim 2, characterized in that: The first limiting mechanism includes a limiting post (4b) provided on the locking latch (4) and a limiting groove (3a) provided on the adjusting piece (3) and matching with the limiting post (4b). The rotation of the limiting post (4b) is limited by the limiting groove (3a) so that there is no freedom degree between the locking latch (4) and the adjusting piece (3), realizing no relative movement between the locking latch (4) and the adjusting piece (3).

4. The lightning protection current mis-tripping structure of a circuit breaker according to claim 2, characterized in that: The adjusting piece (3) is arranged in a semi-circular disk structure. A quenching and tempering groove (3c) is provided on the adjusting piece (3), and a limiting groove (3d) is also provided on the adjusting piece (3). The limiting member in the locking latch (4) passes upward through the limiting groove (3d) and extends upward above the adjusting piece (3). The spring (6) is a torsion spring. One end of the torsion spring is in contact connection with the limiting member extending above the adjusting piece (3), and the other end is in contact connection with the limiting member provided on the contact support (7).

5. The lightning protection current mis-tripping structure of a circuit breaker according to claim 4, characterized in that: The quenching and tempering groove (3c) is arranged outside the limiting groove (3a). The quenching and tempering groove (3c) is used to adjust the centroid position of the adjusting piece (3). By adjusting the centroid position of the adjusting piece (3), the centroid position of the adjusting piece (3) is made to correspond to the centroid position of the locking latch (4), so as to realize that the centroid positions of the locking latch (4) and the adjusting piece (3) are close to their rotation center positions. A quenching and tempering avoidance hole (3e) is also provided on the adjusting piece (3), and the quenching and tempering avoidance hole (3e) is located on the adjusting piece (3) on the side far from the limiting groove (3a).

6. The lightning strike current mis-tripping structure of a circuit breaker according to claim 1, characterized in that: The second limiting mechanism includes a buckle lapping surface (4a) provided on the buckle (4), and a toggle lapping surface (5a) provided on the toggle (5). The buckle (4) and the toggle (5) are in contact with or separated from each other through the buckle lapping surface (4a) and the toggle lapping surface (5a), so as to enable the circuit breaker to be in a normal closing or tripping state; under the action of a spring (6), the buckle (4) controls the accidental tripping action caused by the instantaneous Lorentz force between the buckle lapping surface (4a) and the toggle lapping surface (5a).

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