Short-circuit current-limiting and quick-tripping miniature circuit breaker

Abstract

The utility model relates to a small-sized circuit breaker capable of short-circuit current limiting and rapid tripping. The small-sized circuit breaker comprises a handle, a shell, an electromagnetic tripping system, an arc extinguish chamber, an arc striking system assembly and a moving contact mechanism, the moving contact mechanism comprises a clamping plate, a moving contact, a lock catch, a jump pin and a tripping pull rod, the moving contact is connected with the clamping plate, the moving contact is provided with a contact end, the contact end and the static contact are integrated, when a circuit protected by the circuit breaker breaks down and is short-circuited, the moving contact is bounced off towards the side away from the static contact under the action of electrodynamic force, the antenna on the moving contact ejects the lock catch, and the jump pin is released. The moving contact of the miniature circuit breaker is disconnected; when a circuit protected by the circuit breaker is overloaded, the bimetallic strip bends rightwards to drive the lock catch to move anticlockwise, and the static contact mechanism is tripped. The beneficial effects of the utility model are that through the contact between the moving contact and the static contact, the moving contact mechanism of the circuit breaker is released more quickly when short circuit occurs; the structure is reasonable, the circuit breaker does not occupy too much volume, and the material cost and the production cost are low.

Description

Technical Field

[0001] The utility model relates to the technical field of circuit breakers, in particular to a small circuit breaker with short-circuit current limiting and fast tripping. Background Art

[0002] With the booming development of the electric power era, people have become very skilled in the technology of mastering electricity. In the power system, short circuit faults are inevitable. The circuit breaker and current limiting technology are used to limit the size of the short circuit current to reduce damage to the equipment and ensure the stable operation of the system. The rated short-circuit current breaking capacity of the circuit breaker means that when a short circuit current occurs in the circuit or electrical equipment protected by the circuit breaker, the circuit breaker needs to disconnect the circuit or electrical equipment with the short circuit current fault, thereby playing a protective role.

[0003] When developing circuit breakers, the higher the rated short-circuit current breaking capacity of the circuit breaker, the better the performance of the circuit breaker itself, and the safer the circuit or electrical equipment it protects. The breaking capacity of the rated short-circuit current of the circuit breaker determines the technical design level of the manufacturer. The rated short-circuit current breaking capacity of the circuit breaker determines the safety of the circuit breaker itself and the safety of the circuit protected by the circuit breaker. Therefore, the rated short-circuit current breaking capacity of the circuit breaker is also an important selling point of the circuit breaker. Therefore, many companies that develop and produce circuit breakers have invested a lot of manpower and material resources to improve the short-circuit current breaking capacity of circuit breakers.

[0004] Therefore, in the prior art, since the companies that develop and produce circuit breakers have invested a lot of manpower and material resources to improve the short-circuit current breaking capacity of circuit breakers, the manufacturing cost of circuit breakers with high breaking capacity is very high. There are only a handful of companies in the world that can develop and produce circuit breakers with short-circuit currents above 15KA, which makes it difficult to meet the requirements of the power market.

[0005] Therefore, it is very necessary to provide a small circuit breaker with short-circuit current limiting and fast tripping to solve the above technical problems. Utility Model Content

[0006] The embodiment of the utility model provides a small circuit breaker with short-circuit current limiting and fast tripping, which can solve the problem that the manufacturing cost of circuit breakers with high breaking capacity in the related technology is very high, there are only a handful of companies in the world that can develop and produce circuit breakers with short-circuit currents above 15KA, and it is difficult to meet the requirements of the power market.

[0007] On the one hand, the embodiment of the utility model provides a small circuit breaker with short-circuit current limiting and fast tripping.

[0008] include:

[0009] shell;

[0010] an operating rod rotatably connected to the housing;

[0011] An electromagnetic tripping system, which is arranged in the middle of the housing and located under the operating rod;

[0012] An arc extinguishing chamber, which is arranged at the lower part of the housing and located at the lower side of the electromagnetic tripping system;

[0013] An arc striking system, which is arranged at the lower part of the housing and located on one side of the arc extinguishing chamber;

[0014] A moving contact mechanism, which is arranged in the middle of the housing and located on one side of the electromagnetic tripping system;

[0015] The moving contact mechanism comprises:

[0016] Splints;

[0017] A moving contact connected to the clamping plate, wherein the moving contact is provided with a contact end, and the contact end is connected to a stationary contact, and is used for rebounding away from the stationary contact when the stationary contact is short-circuited;

[0018] The stationary contact is provided with a stationary contact middle portion;

[0019] A lock buckle, which is connected to the clamping plate and is arranged corresponding to the moving contact;

[0020] A tripping pull rod is connected to the lock catch, and a bimetallic strip is connected to the other end of the tripping pull rod, which is used to bend the bimetallic strip to the right to pull the lock catch when the circuit is overloaded, so that the moving contact mechanism is tripped.

[0021] Furthermore, the clamping plate is provided with a clamping plate mounting hole group, and the mounting hole group includes:

[0022] A first clamping plate mounting hole, which is provided in a group and is provided at one end of the clamping plate;

[0023] A second clamping plate mounting hole, which is provided in a group, and the second clamping plate mounting hole is arranged in the middle of the clamping plate;

[0024] A group of third clamping plate mounting holes is provided, and the third clamping plate mounting holes are arranged at the other end of the clamping plate.

[0025] Furthermore, the moving contact is provided with a moving contact mounting hole, and the moving contact mounting hole comprises:

[0026] A first moving contact mounting hole, which is provided in the middle of the moving contact and located between the first clamping plate mounting holes;

[0027] A second moving contact mounting hole, which is provided at an end away from the contact end and is located between the second clamping plate mounting holes;

[0028] A moving contact spring mounting hole is provided on one side of the second moving contact mounting hole. A moving contact mechanism spring is mounted on the moving contact spring mounting hole. One end of the moving contact mechanism spring is connected to the moving contact spring mounting hole, and the other end is connected to the housing base.

[0029] Furthermore, it also includes:

[0030] A short rivet shaft is connected to the first clamping plate mounting hole.

[0031] Furthermore, it also includes:

[0032] A jump buckle is provided with a group of jump buckle mounting holes arranged opposite to each other, the jump buckle mounting holes are arranged on both sides of the third clamping plate mounting hole, and the jump buckle abuts against the lock buckle;

[0033] The jump buckle installation hole is connected with a second long shaft sleeve.

[0034] Furthermore, the moving contact is provided with a moving contact upper feeler, which is used to generate a same-sex magnetic field between the moving contact and the static contact when a fault short-circuit current occurs in the small circuit breaker protection circuit. The moving contact is subjected to an electric repulsive force, and the moving contact rotates counterclockwise. The moving contact upper feeler hits the lock buckle, and the jump buckle is separated from the constraint of the lock buckle, and then rotates clockwise. The moving contact and the overall mechanism are instantly disconnected from the static contact under the action of the moving contact mechanism tension spring, thereby achieving short-circuit protection.

[0035] Furthermore, the lock buckle is provided with a group of lock buckle mounting holes arranged opposite to each other, and the lock buckle mounting holes are provided on both sides of the second clamping plate mounting hole.

[0036] Furthermore, a first long shaft sleeve is connected to the lock buckle mounting hole.

[0037] Furthermore, it also includes:

[0038] A first torsion spring has one end connected to the lock buckle and the other end connected to the clamping plate.

[0039] Furthermore, a heat element system and a soft brush wire are welded in the middle of the static contact.

[0040] The beneficial effects brought by the technical solution provided by the utility model include:

[0041] Through the contact between the moving contact and the static contact, when a short circuit occurs in the circuit, the moving contact pops open in the counterclockwise direction under the action of the electric force, and the antenna on the moving contact pushes open the lock. At this time, the circuit breaker is disconnected, which is the short-circuit protection; when the circuit protected by the circuit breaker is overloaded, the bimetallic strip bends to the right, driving the tripping rod to pull the lock to rotate counterclockwise, thereby achieving tripping. The present application has a reasonable structure, the circuit breaker does not occupy too much volume, and the material cost and production cost are relatively low, which overcomes the problem in the prior art that the companies that develop and produce circuit breakers have invested a lot of manpower and material resources to improve the short-circuit current breaking capacity of the circuit breakers, resulting in the price of circuit breakers with high breaking capacity being usually high, and the volume of circuit breakers with high breaking capacity is usually large and the structure is relatively complex. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0043] Figure 1 This is one of the structural schematic diagrams of a small circuit breaker with short-circuit current limiting and fast tripping according to the utility model;

[0044] Figure 2 This is the second schematic diagram of a small circuit breaker with short-circuit current limiting and fast tripping according to the utility model;

[0045] Figure 3 It is a schematic diagram of a clamping plate in a small circuit breaker with short-circuit current limiting and quick tripping according to the utility model;

[0046] Figure 4 It is a schematic diagram of a moving contact in a small circuit breaker with short-circuit current limiting and fast tripping according to the utility model;

[0047] Figure 5 It is a schematic diagram of a tripping button in a small circuit breaker with short-circuit current limiting and fast tripping according to the utility model;

[0048] Figure 6 This is one of the schematic diagrams of a lock in a small circuit breaker with short-circuit current limiting and quick tripping according to the utility model;

[0049] Figure 7 This is a second schematic diagram of a lock in a small circuit breaker with short-circuit current limiting and quick tripping according to the utility model;

[0050] Figure 8 It is a schematic diagram of the use of a small circuit breaker with short-circuit current limiting and quick tripping according to the utility model;

[0051] Fig. 9 This is one of the schematic diagrams of the thermal element system and arc-starting piece in a small circuit breaker with short-circuit current limiting and fast tripping of the utility model;

[0052] Fig.10 This is the second schematic diagram of the thermal element system and arc-starting piece in a small circuit breaker with short-circuit current limiting and fast tripping according to the utility model.

[0053] In the figure: 1. clamping plate; 2. moving contact; 3. contact end; 4. lock; 5. release rod; 6. first clamping plate mounting hole; 7. second clamping plate mounting hole; 8. third clamping plate mounting hole; 9. first moving contact mounting hole; 10. second moving contact mounting hole; 11. short rivet shaft; 12. lock mounting hole; 13. first long shaft sleeve; 14. jump buckle; 15. jump buckle mounting hole; 16. second long shaft sleeve; 17. first torsion spring; 18. moving contact mechanism tension spring; 19. static contact; 20. bimetallic strip; 21. upper antenna of moving contact; 22. middle part of static contact; 23. moving contact tension spring mounting hole; 24. thermal element system; 25. soft brush wire; A. operating lever; B. housing; C. electromagnetic tripping system; D. arc extinguishing chamber; E. arc striking system; F moving contact mechanism. DETAILED DESCRIPTION

[0054] In order to make the purpose, technical solution and advantages of the embodiment of the utility model clearer, the technical solution in the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiment of the utility model. Obviously, the described embodiment is a part of the embodiment of the utility model, not all of the embodiments. Based on the embodiment of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0055] See also Figure 1 , Figure 2 , Figure 8 and Fig. 9 As shown, the embodiment of the utility model provides a small circuit breaker with short-circuit current limiting and fast tripping.

[0056] It includes a housing B, an operating rod A, an electromagnetic tripping system C, an arc extinguishing chamber D, an arc striking system E and a moving contact mechanism F, wherein the operating rod A is rotatably connected to the housing B; the electromagnetic tripping system C is arranged in the middle of the housing B and is located at the lower side of the operating rod A; the arc extinguishing chamber D is arranged in the lower part of the housing B and is located at the lower side of the electromagnetic tripping system C; the arc striking system E is arranged in the lower part of the housing B and is located on one side of the arc extinguishing chamber D; the moving contact mechanism F is arranged in the middle of the housing B and is located on one side of the electromagnetic tripping system C;

[0057] The moving contact mechanism F includes a clamping plate 1, a moving contact 2, a lock 4 and a tripping rod 5. The moving contact 2 is connected to the clamping plate 1, and the moving contact 2 is provided with a contact end 3. The contact end 3 is connected with a static contact 19, which is used to bounce away from the static contact 19 when the static contact 19 is short-circuited. The static contact 19 is provided with a static contact middle part 22; the lock 4 is connected to the clamping plate 1 and is correspondingly arranged with the moving contact 2; the tripping rod 5 is connected to the lock 4, and the other end of the tripping rod 5 is connected with a bimetallic strip 20, which is used to bend the bimetallic strip 20 to the right to pull the lock when the circuit is overloaded, so that the moving contact mechanism F is tripped.

[0058] In this embodiment, the moving contact is in contact with the static contact. When a short circuit occurs in the circuit breaker protection circuit, the moving contact is ejected away from the static contact under the action of the electric force, and the antenna on the moving contact hits the lock, so that the moving contact mechanism of the circuit breaker is tripped more quickly. Adding a turn of arc blowing coil in the middle of the arc striking system increases the resistance of the arc striking sheet, reduces the arc voltage, and increases the magnetic field force of the arc striking system, so as to quickly disconnect the arc between the moving and static contacts and blow it into the arc extinguishing chamber to extinguish it, and effectively improve the short-circuit current breaking capacity of the circuit breaker.

[0059] In addition, if Figure 8 In the laboratory, the rated short-circuit breaking current capability test is performed: the expected short-circuit current is set to 10KA, the voltage is 230V, and the frequency is 50Hz. When the short-circuit current rises to the IP value of 2.2-3KA in about 2mS, the moving and static contacts have downward and upward currents passing through them respectively (indicated by arrows). According to the right-hand solenoid rule: a magnetic field of the same sex is generated between the moving and static contacts, generating an electromotive repulsive force. The moving contact is ejected to the right under the electromotive repulsive force (rightward arrow), and an arc is generated between the moving and static contacts. If the moving iron core of the electromagnetic system pushes the top rod to hit the lock, the moving contact mechanism is immediately disconnected, and the arc between the moving and static contacts will also be elongated and disconnected. After the arc is disconnected, it enters the arc extinguishing chamber along the static contact, and at the same time, it transitions along the moving contact to the arc-starting piece and enters the arc extinguishing chamber and extinguishes within 3-5mS... This is a process of the laboratory's rated short-circuit breaking current capability test. The expected short-circuit current is 10KA, and the Ip value is 2.2~3KA. This Ip value reflects the current limiting characteristics of the miniature circuit breaker! The smaller the Ip value during the test, the better the power performance of the short-circuit current breaking capacity of the miniature circuit breaker.

[0060] In some embodiments, the splint 1 is provided with a splint mounting hole group, and the mounting hole group includes a first splint mounting hole 6, a second splint mounting hole 7 and a third splint mounting hole 8, the first splint mounting holes 6 are provided with a group, and the first splint mounting holes 6 are provided at one end of the splint 1; the second splint mounting holes 7 are provided with a group, and the second splint mounting holes 7 are provided in the middle of the splint 1; the third splint mounting holes 8 are provided with a group, and the third splint mounting holes 8 are provided at the other end of the splint 1.

[0061] In some embodiments, the moving contact 2 is provided with a moving contact mounting hole, and the moving contact mounting holes include a first moving contact mounting hole 9, a second moving contact mounting hole 10 and a moving contact tension spring mounting hole 23, the first moving contact mounting hole 9 is arranged in the middle of the moving contact 2, and is located between the first clamping plate mounting holes 6; the second moving contact mounting hole 10 is arranged at the end away from the contact end 3, and is located between the second clamping plate mounting holes 7; the moving contact tension spring mounting hole 23 is arranged on one side of the second moving contact mounting hole 10, and a moving contact mechanism tension spring 18 is installed on the moving contact tension spring mounting hole 23, one end of the moving contact mechanism tension spring 18 is connected to the moving contact tension spring mounting hole 23, and the other end is connected to the housing base.

[0062] In this embodiment, when a short circuit occurs in the circuit protected by the circuit breaker of the present application, the upper antenna 21 of the moving contact 2 hits the lock 4, and after pushing the lock 4 open, it rotates counterclockwise, causing the circuit breaker to trip, thereby disconnecting the circuit.

[0063] In some embodiments, a short rivet shaft 11 is further included, and the short rivet shaft 11 is connected to the first clamping plate mounting hole 6 .

[0064] In some embodiments, a jump buckle 14 is also included, and the jump buckle 14 is provided with a group of relatively arranged jump buckle mounting holes 15, and the jump buckle mounting holes 15 are arranged on both sides of the third splint mounting hole 8, and the jump buckle 14 is abutted against the lock buckle 4; the jump buckle mounting hole 15 is connected to a second long shaft sleeve 16.

[0065] See also Figure 1 and Figure 2 As shown, in this embodiment, one end of the first torsion spring 17 is connected to the lock buckle 4 , and the other end is connected to the clamping plate 1 , so that a certain rebound force is formed between the lock buckle 4 and the clamping plate 1 .

[0066] At the same time, it should be noted that the best choice in this embodiment is a torsion spring, and a rebounder with elastic force can also be used, all of which are within the scope of protection of this application.

[0067] In some embodiments, the moving contact 2 is provided with a moving contact upper antenna 21, which is used to generate a same-sex magnetic field between the moving contact 2 and the static contact 19 when a fault short-circuit current occurs in the small circuit breaker protection circuit. The moving contact 2 is subjected to an electric repulsive force and rotates in a counterclockwise direction. The moving contact upper antenna 21 hits the lock buckle 4, and the jump buckle 14 is separated from the constraint of the lock buckle 4, and then rotates in a clockwise direction. The moving contact 2 and the overall mechanism are instantly disconnected from the static contact 19 under the action of the moving contact mechanism tension spring 18, thereby achieving short-circuit protection.

[0068] In some embodiments, the lock buckle 4 is provided with a group of lock buckle mounting holes 12 arranged opposite to each other, and the lock buckle mounting holes 12 are provided on both sides of the second clamping plate mounting hole 7 .

[0069] See also Figure 1 , Figure 2 and Figure 7 As shown, in this embodiment, the tail of the lock 4 can also be provided with an arc structure to achieve a better triggering effect. It should be noted that the tail of the lock 4 is provided with a right-angle structure and a trapezoidal structure, etc., to better trigger the reaction of the circuit breaker, which all fall within the protection scope of this application.

[0070] In some embodiments, the lock mounting hole 12 is connected to a first long shaft sleeve 13 .

[0071] See also Figure 1 , Figure 2 and Figure 5 As shown, in some embodiments, a jump buckle 14 is further included. The jump buckle 14 is provided with a group of jump buckle mounting holes 15 arranged opposite to each other. The jump buckle mounting holes 15 are provided on both sides of the third splint mounting hole 8 . The jump buckle 14 abuts against the lock buckle 4 .

[0072] In some embodiments, a first torsion spring 17 is further included, one end of the first torsion spring 17 is connected to the lock buckle 4 , and the other end of the first torsion spring 17 is connected to the clamp 1 .

[0073] In some embodiments, a heat element system 24 and a soft brush wire 25 are welded to the middle portion 22 of the static contact.

[0074] The operation mode of the utility model is as follows:

[0075] See also Figure 8 and Fig. 9 As shown, the upward arrow direction at the static contact 19 is the current direction of the static contact 19 ; the downward arrow direction at the moving contact 2 is the current direction of the moving contact 2 .

[0076] According to the right-hand screw rule of Ampere's law: When the small circuit breaker is in normal working state, magnetic fields will be generated on the moving contact 2 and the static contact 19, and the magnetic force directions of the magnetic fields are the same. Therefore, the moving contact 2 and the static contact 19 will generate magnetic fields of the same sex, which will generate mutual repulsion. The rightward arrow F on the moving contact 2 indicates the direction of movement of the electromotive force repulsion on the moving contact. Therefore, the moving contact of the small circuit breaker is required to have a certain final pressure to overcome the bouncing of the moving contact, thereby ensuring that the small circuit breaker can work normally.

[0077] When the moving contact 2 moves about 0.5 mm in the counterclockwise direction under the electromotive force of a large short-circuit current, the feeler on the moving contact 2 can push the lock 4 to move more than 1.0 mm in the counterclockwise direction. Then the miniature circuit breaker can be disconnected immediately, achieving the goal of rapid disconnection.

[0078] For example, the final pressure of the moving contact 2 of a 63A miniature circuit breaker is between 4 and 5 N. According to the calculation of 5 N, if the moving contact 2 moves 1 mm to the right within 1 ms under the action of the electric force.

[0079] according to:

[0080] Wa=F(N)×S(m) / t(s)=5×(1 / 1000)÷(0.001 / 1000)=5(watts);

[0081] Therefore, as long as the work done by the repulsive force generated on the moving contact 2 and the static contact 19 reaches more than 5 watts, the small circuit breaker with short-circuit current limiting and fast tripping can achieve the effect of fast tripping. 5 watts is a constant value for the fast tripping of this moving contact structure. Most of the alternating current is 50Hz. The larger the fault short-circuit current, the shorter the time it takes for the work done by the electric repulsion to reach 5 watts. For example: when 230V, 50Hz, and the expected short-circuit current of 15KA, 20KA, or 30KA are applied to the circuit breaker, the time it takes for the work done by the electric repulsion to reach 5 watts will be shorter (because the alternating current changes in a sinusoidal wave, that is, the short-circuit current will rise from 0 to 15KA, 20KA or 30KA to reach the expected value in 0-5ms.) The moving contact mechanism will trip faster. This achieves the goal of short-circuit current limiting and fast short-opening. It also makes the protected circuit safer. There is another advantage: the moving contact is subjected to electric repulsion to touch the lock to trip the moving contact mechanism, overcoming the phenomenon that when a circuit fails and shorts, the moving contact will bounce open and fall under the action of electric force, causing the arc to reignite. By using the moving contact to touch the lock to trip the moving contact mechanism under the electric repulsion force, the small circuit breaker solves the historical problem of arc reignition during the current short circuit process.

[0082] The beneficial effects of the utility model are:

[0083] Through the contact between the moving contact and the static contact, when a short circuit occurs in the circuit, the moving contact pops open in the counterclockwise direction under the action of the electric force, and the antenna on the moving contact pushes open the lock. At this time, the circuit breaker is disconnected, which is the short-circuit protection; when the circuit protected by the circuit breaker is overloaded, the bimetallic strip bends to the right, driving the tripping rod to pull the lock to rotate counterclockwise, thereby achieving tripping. The present application has a reasonable structure, the circuit breaker does not occupy too much volume, and the material cost and production cost are relatively low, which overcomes the problem in the prior art that the companies that develop and produce circuit breakers have invested a lot of manpower and material resources to improve the short-circuit current breaking capacity of the circuit breakers, resulting in the price of circuit breakers with high breaking capacity being usually high, and the volume of circuit breakers with high breaking capacity is usually large and the structure is relatively complex.

[0084] In the description of the present utility model, it should be noted that the terms "upper", "lower", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as a limitation on the present utility model. Unless otherwise clearly specified and limited, the terms "set", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to the specific circumstances.

[0085] It should be noted that, in this application, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the term "comprises" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0086] The above description is only a specific embodiment of the utility model, so that those skilled in the art can understand or implement the utility model. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the utility model. Therefore, the utility model will not be limited to the embodiments shown herein, but should conform to the widest scope consistent with the principles and novel features of the utility model described herein.

Claims

1. A short-circuit current limiting and fast tripping miniature circuit breaker, characterized in that: include: Shell (B); an operating rod (A) rotatably connected to the housing (B); An electromagnetic tripping system (C), which is arranged in the middle of the housing (B) and located under the operating rod (A); An arc extinguishing chamber (D), which is arranged at the lower part of the housing (B) and is located at the lower side of the electromagnetic tripping system (C); An arc striking system (E), which is arranged at the lower part of the housing (B) and located on one side of the arc extinguishing chamber (D); A moving contact mechanism (F), which is arranged in the middle of the housing (B) and located on one side of the electromagnetic tripping system (C); The moving contact mechanism (F) comprises: Splint (1); A moving contact (2) connected to the clamping plate (1), wherein the moving contact (2) is provided with a contact end (3), wherein the contact end (3) is connected to a stationary contact (19) and is used for being ejected away from the stationary contact (19) when the stationary contact (19) is short-circuited; The stationary contact (19) is provided with a stationary contact middle part (22); A lock buckle (4), which is connected to the clamping plate (1) and is arranged corresponding to the moving contact (2); A tripping pull rod (5) is connected to the lock catch (4), and the other end of the tripping pull rod (5) is connected to a bimetallic strip (20) for bending the bimetallic strip (20) to the right to pull the lock catch when the circuit is overloaded, thereby tripping the moving contact mechanism (F).

2. A short-circuit current limiting and fast-tripping miniature circuit breaker as claimed in claim 1, characterized in that: The clamping plate (1) is provided with a clamping plate mounting hole group, and the mounting hole group comprises: A first clamping plate mounting hole (6), which is provided in a group, and the first clamping plate mounting hole (6) is provided at one end of the clamping plate (1); A second clamping plate mounting hole (7), of which a group is provided, and the second clamping plate mounting hole (7) is arranged in the middle of the clamping plate (1); A group of third clamping plate mounting holes (8) are provided, and the third clamping plate mounting holes (8) are provided at the other end of the clamping plate (1).

3. A short-circuit current limiting and fast-tripping miniature circuit breaker as claimed in claim 2, characterized in that: The moving contact (2) is provided with a moving contact mounting hole, and the moving contact mounting hole comprises: A first moving contact mounting hole (9), which is arranged in the middle of the moving contact (2) and is located between the first clamping plate mounting holes (6); A second moving contact mounting hole (10), which is arranged at an end away from the contact end (3) and is located between the second clamping plate mounting holes (7); A moving contact tension spring mounting hole (23) is arranged on one side of the second moving contact mounting hole (10); a moving contact mechanism tension spring (18) is mounted on the moving contact tension spring mounting hole (23); one end of the moving contact mechanism tension spring (18) is connected to the moving contact tension spring mounting hole (23), and the other end is connected to the housing base.

4. A short-circuit current limiting and fast-tripping miniature circuit breaker as claimed in claim 3, characterized in that: Also includes: A short rivet shaft (11) is connected to the first clamping plate mounting hole (6).

5. A short-circuit current limiting and fast-tripping miniature circuit breaker as claimed in claim 3, characterized in that: Also includes: A jump buckle (14) is provided with a group of jump buckle mounting holes (15) arranged opposite to each other, wherein the jump buckle mounting holes (15) are arranged on both sides of the third clamping plate mounting hole (8), and the jump buckle (14) abuts against the lock buckle (4); The jump buckle installation hole (15) is connected to a second long shaft sleeve (16).

6. A short-circuit current limiting and fast-tripping miniature circuit breaker as claimed in claim 5, characterized in that: The moving contact (2) is provided with a moving contact upper feeler (21), which is used to generate a same-sex magnetic field between the moving contact (2) and the stationary contact (19) when a short-circuit current occurs in the protection circuit of the small circuit breaker. The moving contact (2) is subjected to an electric repulsive force, and the moving contact (2) rotates in a counterclockwise direction. The moving contact upper feeler (21) hits the lock buckle (4), and the jump buckle (14) is separated from the constraint of the lock buckle (4), and then rotates in a clockwise direction. The moving contact (2) and the entire mechanism are instantly disconnected from the stationary contact (19) under the action of the moving contact mechanism tension spring (18), thereby achieving short-circuit protection.

7. A short-circuit current limiting and fast-tripping miniature circuit breaker as claimed in claim 2, characterized in that: The lock buckle (4) is provided with a group of lock buckle mounting holes (12) arranged opposite to each other, and the lock buckle mounting holes (12) are arranged on both sides of the second clamping plate mounting hole (7).

8. A short-circuit current limiting and fast-tripping miniature circuit breaker as claimed in claim 7, characterized in that: The lock buckle installation hole (12) is connected to a first long shaft sleeve (13).

9. A short-circuit current limiting and fast-tripping miniature circuit breaker as claimed in claim 1, characterized in that: Also includes: A first torsion spring (17) has one end connected to the lock buckle (4) and the other end connected to the clamping plate (1).

10. A short-circuit current limiting and fast-tripping miniature circuit breaker as claimed in claim 1, characterized in that: A heat element system (24) and a soft brush wire (25) are welded to the middle part (22) of the static contact.

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