A miniature circuit breaker
By tilting the Laval nozzle at the arc-initiating angle of the N-pole moving contact and adjusting the contact distance at the breaking position, the problem of arc jump is solved, achieving a more efficient arc extinguishing effect.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- ZHEJIANG JIUCE INTELLIGENT ELECTRIC CO LTD
- Filing Date
- 2025-08-25
- Publication Date
- 2026-07-21
AI Technical Summary
The existing N-pole moving contact arc initiation angle setting distance is too far, making it difficult for the arc to jump, resulting in an unsatisfactory arc extinguishing effect. Furthermore, the parallel setting of the N-pole moving and stationary contacts at the break point is not conducive to arc transfer.
The first end of the arc-initiating angle of the N-pole moving contact is tilted to form a Laval nozzle, and the distance between the N-pole moving contact and the arc-initiating angle is made smaller than the distance between the moving contact and the stationary contact when the contact is broken. At the same time, an inclined transition section and an arc-extinguishing chamber are provided to improve the arc velocity and the arc-extinguishing effect.
It enhances the arc's movement speed and arc-extinguishing effect, making it easier for the arc to lengthen through the arc-starting angle, thus improving the arc-extinguishing performance of the circuit breaker.
Smart Images
Figure CN224537035U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of circuit breakers, specifically a miniature circuit breaker. Background Technology
[0002] A DPN circuit breaker, also known as a 1P+N circuit breaker, has its internal casing divided into two spaces: one space houses the L-pole contact assembly and the arc-extinguishing chamber, and the other space houses the N-pole contact assembly.
[0003] The N-pole contact assembly includes an N-pole moving contact and an N-pole stationary contact. To ensure their arc-extinguishing performance, an arc-initiating angle is set for the N-pole moving contact, and the N-pole stationary contact is configured to include an N-pole stationary contact segment and an N-pole arc-initiating angle segment. In this way, when the N-pole contact assembly breaks, the arc can be continuously lengthened through the two arc-initiating angles to achieve arc extinguishing.
[0004] Of course, in order to further improve the arc extinguishing effect, some manufacturers will also set up an N-pole arc extinguishing chamber. In this way, the arc is continuously stretched through the two arc-starting angles and enters the arc extinguishing chamber, where it is quickly extinguished.
[0005] However, the existing N-pole moving contact arc-initiating angle is set far from the N-pole moving contact, making it difficult for the arc root on the N-pole moving contact to jump to the N-pole moving contact arc-initiating angle, as disclosed in patent CN209626171U. Furthermore, the end of the N-pole moving contact arc-initiating angle near the break point of the N-pole moving and stationary contacts is basically parallel to the N-pole stationary contact. This parallel structure is not conducive to the transfer of the arc from the break point of the N-pole moving and stationary contacts to the next area, resulting in a very unsatisfactory arc-extinguishing effect. Summary of the Invention
[0006] In view of this, the purpose of this application is to overcome the shortcomings of the prior art and to provide a miniature circuit breaker.
[0007] This application provides: a miniature circuit breaker, comprising a circuit breaker housing, an L-pole contact assembly, and an N-pole contact assembly, wherein the circuit breaker housing houses and separates the L-pole contact assembly and the N-pole contact assembly; wherein the N-pole contact assembly includes an N-pole moving contact and an N-pole stationary contact, the N-pole stationary contact being provided with a first contact surface for the N-pole moving contact to contact; it also includes an N-pole moving contact arc-starting angle, the first end of the N-pole moving contact arc-starting angle being inclined, the first end forming a Laval nozzle with the first contact surface; when the N-pole moving contact is in the open position, the distance between the N-pole moving contact and the N-pole moving contact arc-starting angle is less than the distance between the N-pole moving contact and the N-pole stationary contact.
[0008] In some embodiments of this application, an electromagnetic trip unit and an operating mechanism are also included. The L-pole contact assembly includes an L-pole moving contact and an L-pole stationary contact. Both the L-pole moving contact and the N-pole moving contact are disposed on the operating mechanism and driven by the operating mechanism. The electromagnetic trip unit is used to trigger the operating mechanism to perform a tripping operation when a short circuit occurs in the line. The electromagnetic trip unit includes a coil, a frame, a magnetic yoke, a moving iron core, a push rod, a stationary iron core, and a reset spring. The moving iron core is slidably disposed in the frame, and the stationary iron core is fixed to the frame to seal the opening of the frame. One end of the push rod is inserted into the moving iron core and abuts against the moving iron core, and the other end of the push rod penetrates the stationary iron core to trigger the operating mechanism. The reset spring abuts between the push rod and the stationary iron core. The coil is wound on the frame, and the magnetic yoke is arranged around the periphery of the frame.
[0009] In some embodiments of this application, the moving iron core has a mating groove with the groove opening facing the stationary iron core, and one end of the push rod abuts against the bottom of the mating groove; the push rod has a stepped structure, the stepped structure is located inside the mating groove, and the return spring abuts against the stepped structure.
[0010] In some embodiments of this application, the dimension of the push rod in the first direction is greater than the dimension of the moving iron core in the first direction, and the dimension of the moving iron core in the first direction is greater than the dimension of the stationary iron core in the first direction.
[0011] In some embodiments of this application, the skeleton has a sliding cavity, and the moving iron core always extends beyond the centerline of the sliding cavity in a first direction.
[0012] In some embodiments of this application, the side of the skeleton away from the opening has a sidewall with a through hole, the cross-sectional area of the through hole in the radial direction being smaller than the cross-sectional area of the moving iron core in the radial direction.
[0013] In some embodiments of this application, the first N-pole terminal, the second N-pole terminal, the first N-pole terminal, the moving N-pole contact, and the arc-leading angle of the moving N-pole contact are all at the same potential, and the second N-pole terminal and the stationary N-pole contact are at the same potential.
[0014] In some embodiments of this application, the N-pole first terminal includes an N-pole first plate, and the N-pole first plate, the N-pole moving contact, and the N-pole moving contact arc-leading angle are connected by a soft connection to form an equipotential.
[0015] In some embodiments of this application, the N-pole second terminal includes an N-pole second plate, and the N-pole second plate and the N-pole stationary contact are integrally formed to form an equipotential, or are welded to form an equipotential, or are formed to form an equipotential through a soft connection.
[0016] In some embodiments of this application, the arc-drawing angle of the N-pole moving contact includes a transition portion and a second end portion, the transition portion connecting the first end portion and the second end portion; in a first direction, the first end portion is located between the N-pole stationary contact and the N-pole first terminal; the first end portion gradually tilts towards the N-pole first terminal from the end connected to the transition portion to the end away from the transition portion, so as to form an inclined arrangement of the first end portion.
[0017] In some embodiments of this application, the N-pole moving contact arc-starting angle includes a transition portion and a second end portion, the transition portion connecting the first end portion and the second end portion; the N-pole stationary contact is provided with an N-pole stationary contact arc-starting angle, the first end of the N-pole stationary contact arc-starting angle being connected to the first contact surface; it also includes an arc-extinguishing chamber, the arc-extinguishing chamber being disposed above the second end portion, and the arc inlet of the arc-extinguishing chamber being adjacent to the second end of the N-pole stationary contact arc-starting angle.
[0018] In some embodiments of this application, when the N-pole moving contact is in the disconnected position, there is an overlap between the N-pole moving contact and the first end in the second direction.
[0019] The advantages of this application compared to the prior art are: Compared to existing technologies, the first end of the arc-initiating angle of the N-pole moving contact is changed to an inclined setting. This makes the first end and the first contact surface form a Laval nozzle. The Laval nozzle will help increase the flow rate of gas (gas generated by the arc burning the plastic inside the circuit breaker during disconnection), increase the movement speed of the arc, and make it easier for the arc to be elongated and extinguished through the two arc-initiating angles of the N-pole (specifically, the two arc-initiating angles move away from the N-pole moving and stationary contacts). Attached Figure Description
[0020] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.
[0021] Figure 1 A perspective view of a miniature circuit breaker according to an embodiment of this application is shown; Figure 2 A schematic diagram of the internal structure of the N pole of a miniature circuit breaker according to an embodiment of this application is shown; Figure 3 A schematic diagram of the operating mechanism and contact structure of a miniature circuit breaker according to an embodiment of this application is shown; Figure 4 A schematic diagram of the Laval nozzle structure in an embodiment of this application is shown; Figure 5 This illustration shows a schematic diagram of the N-pole moving contact in the disconnected position in an embodiment of this application. Figure 6 A cross-sectional view of the electromagnetic trip unit in an embodiment of this application is shown. Detailed Implementation
[0022] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.
[0023] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.
[0024] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.
[0025] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; 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; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.
[0026] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature. Example
[0027] like Figures 1-6 As shown, a miniature circuit breaker includes a circuit breaker housing 100, and inside the circuit breaker housing 100 are arranged an operating mechanism 200, an electromagnetic trip unit 300, an L-pole contact assembly 400, an N-pole contact assembly 500, an N-pole first terminal 530, an N-pole second terminal 540, etc.
[0028] The circuit breaker housing 100 includes a first housing 110, a second housing 120, and a third housing 130, which are connected together and fastened with rivets.
[0029] The L-pole contact assembly 400 is disposed within the space formed by the first housing 110 and the second housing 120, and the N-pole contact assembly 500 is disposed within the space formed by the second housing 120 and the third housing 130. In this way, the second housing 120 effectively separates the L-pole contact assembly 400 and the N-pole contact assembly 500.
[0030] The operating mechanism 200 employs a four-bar linkage, which includes components such as a handle, connecting rods, trip latch, latch 210, and contact support 220. These are common knowledge in the field and will not be described further here. Alternatively, an operating mechanism 200 without a trip latch can also be used; this is also common knowledge and will not be described further here. Regardless of whether the four-bar linkage has a trip latch or not, when the circuit is closed, if the latch 210 is rotated, the temporary stable state of the mechanism will be broken, and the operating mechanism 200 will perform a trip operation.
[0031] There are many situations that can cause the latch 210 to rotate. It can be caused by overload or short circuit (that is, caused by the actuation of the electromagnetic trip unit 300 as mentioned below).
[0032] The L-pole contact assembly 400 includes an L-pole moving contact and an L-pole stationary contact. In order to facilitate the arc extinguishing when the L-pole contact assembly 400 breaks, it also includes an arc-starting angle and an arc-extinguishing chamber related to the L-pole contact assembly 400. This application mainly focuses on the improvements related to the N-pole structure, so the L-pole contact assembly 400 will not be described in detail.
[0033] The N-pole contact assembly 500 includes an N-pole moving contact 510 and an N-pole stationary contact 520.
[0034] Here, both the L-pole moving contact and the N-pole moving contact 510 are mounted on the operating mechanism 200, specifically on the contact support 220. Therefore, driven by the same operating mechanism 200, the L-pole moving contact can separate from and make contact with the L-pole stationary contact, and the N-pole moving contact 510 can separate from and make contact with the N-pole stationary contact 520.
[0035] To facilitate arc extinguishing when the N-pole contact assembly 500 breaks (that is, to eliminate the separation of the N-pole moving contact 510 and the N-pole stationary contact 520).
[0036] A Laval nozzle W is formed between the arc-drawing angle 60° of the N-pole moving contact and the N-pole stationary contact 520. Specifically, the N-pole stationary contact 520 is provided with a first contact surface 520a for the N-pole moving contact 510 to contact. Here, the N-pole stationary contact 520 can be a structure with silver contacts, in which case the surface of the silver contacts that contacts the N-pole moving contact 510 is the first contact surface 520a; or the N-pole stationary contact 520 can be a structure without silver contacts, that is, the surface of the N-pole stationary contact 520 directly contacts the N-pole moving contact 510, in which case the surface of contact is the first contact surface 520a.
[0037] The end of the N-pole moving contact 510 closest to the arc-initiating angle 600 of the N-pole moving contact is the first end 600a. The first end 600a is inclined, thus forming a Laval nozzle W with the first contact surface 520a. Here, the Laval nozzle W is the area where the N-pole moving contact 510 and the N-pole stationary contact 520 are separated; the opening gradually narrows (from the outside of the two arc-initiating angles in the diagram). This structure helps the arc move away from the area where the N-pole moving contact 510 and the N-pole stationary contact 520 are separated, which is beneficial for arc extinguishing. Specifically, the Laval nozzle W helps increase the flow rate of the gas inside the circuit breaker (the gas generated during disconnection due to the arc burning of the plastic and other materials inside the circuit breaker), increasing the arc's movement speed, making it easier for the arc to be elongated and extinguished via the two arc-initiating angles of the N-pole (specifically, the two arc-initiating angles move away from the N-pole moving and stationary contacts).
[0038] Here, when the N-pole moving contact 510 is in the broken position, the distance between the N-pole moving contact 510 and the N-pole moving contact arc-starting angle 600 is less than the distance between the N-pole moving contact 510 and the N-pole stationary contact 520. In other words, the N-pole moving contact 510 is closer to the N-pole moving contact arc-starting angle 600, making it easier for the arc root on the N-pole moving contact 510 to jump to the N-pole moving contact arc-starting angle 600.
[0039] For the N-pole first terminal 530 and the N-pole second terminal 540, the N-pole first terminal 530 connects the N-pole moving contact 510 to the circuit, and the N-pole second terminal 540 connects the N-pole stationary contact 520 to the circuit. Therefore, the N-pole first terminal 530 and the N-pole moving contact 510 are at the same potential, and the N-pole second terminal 540 and the N-pole stationary contact 520 are at the same potential. Here, the N-pole moving contact arc-starting angle 600 is also at the same potential as the N-pole first terminal 530 and the N-pole moving contact 510. This equipotential structure will be more conducive to the arc root jump on the N-pole moving contact 510 to the N-pole moving contact arc-starting angle 600.
[0040] There are many ways to form an equipotential bond, including both soft and hard connections.
[0041] Taking the N-pole moving contact 510 as an example, the N-pole first terminal 530 includes an N-pole first plate 530a (made of conductive material). The N-pole first plate 530a, the N-pole moving contact 510, and the N-pole moving contact arc-starting angle 600 are connected by flexible connections to form an equipotential. Specifically, the N-pole first plate 530a and the N-pole moving contact 510 are connected by flexible connections, and the N-pole moving contact arc-starting angle 600 is connected to the N-pole moving contact 510 by another flexible connection.
[0042] Taking the N-pole stationary contact 520 as an example, the N-pole second terminal 540 includes an N-pole second plate 540a (made of conductive material). The N-pole second plate 540a and the N-pole stationary contact 520 are an integral structure that forms an equipotential. Of course, in addition, the N-pole second plate 540a and the N-pole stationary contact 520 can also be separate structures, and then form an equipotential by welding or flexible connection welding.
[0043] For the N-pole first terminal 530 and the N-pole second terminal 540, both can be screw-type terminals, cage-type terminals, clip-type structures, or protruding weld feet of the circuit breaker housing 100, as long as it can ensure that the circuit breaker can be connected to the line using the N-pole first terminal 530 and the N-pole second terminal 540.
[0044] The arc-starting angle 600 of the N-pole moving contact also includes a transition portion 600b and a second end portion 600c, with the transition portion 600b connecting the first end portion 600a and the second end portion 600c. In the first direction F1 (the length direction of the circuit breaker), the first end portion 600a is located between the N-pole stationary contact 520 and the N-pole first terminal 530. Specifically, the first end portion 600a is inclined such that it gradually tilts towards the direction of the N-pole first terminal 530 from the end connected to the transition portion 600b to the end away from the transition portion 600b. This tilting arrangement is very beneficial for forming the Laval nozzle W, and also facilitates the arc root of the N-pole moving contact 510 jumping to the first end portion 600a.
[0045] To further facilitate arc extinguishing, an arc-extinguishing chamber, specifically an N-pole arc-extinguishing chamber 700, is included. The N-pole arc-extinguishing chamber 700 is located above the second end 600c. The N-pole stationary contact 520 has an N-pole stationary contact arc-initiating angle 520b. The first end of the N-pole stationary contact arc-initiating angle 520b is connected to the first contact surface 520a, while the second end is bent to one side. Specifically, the arc inlet of the arc-extinguishing chamber is adjacent to the second end of the N-pole stationary contact arc-initiating angle 520b. This allows the arc on the stationary contact to jump along the N-pole stationary contact arc-initiating angle 520b to the N-pole arc-extinguishing chamber 700, which is more conducive to arc extinguishing. Simultaneously, since the N-pole arc-extinguishing chamber 700 is located above the second end 600c, the arc on the N-pole moving arc-initiating angle can enter the N-pole arc-extinguishing chamber 700 through the second end 600c.
[0046] In the second direction F2, there is an overlap between the N-pole moving contact 510 and the first end 600a. That is, whether the N-pole moving contact 510 is in the contact position or the disconnected position, there is always an overlap between it and the first end 600a. This structure will make the disconnection area of the moving and stationary contacts within the Laval nozzle W, which will be more conducive to the rapid transfer of the arc.
[0047] The electromagnetic trip unit 300 is used to trigger the operating mechanism 200 to perform a tripping operation when a short circuit occurs in the line. Specifically, it includes a coil 300a, a frame 300b, a magnetic yoke 300c, a moving iron core 300d, a push rod 300e, a stationary iron core 300f, and a reset spring 300g. The coil 300a is wound around the frame 300b, and the magnetic yoke 300c is located around the frame 300b. The coil 300a is a component of the main conductor of the L-pole line (this is known technology and will not be elaborated further). The frame 300b has a sliding cavity inside, the moving iron core 300d is slidably disposed within the frame 300b, and the stationary iron core 300f is fixed to the frame 300b, sealing the opening of the frame 300b. One end of the push rod 300e is inserted into and abuts against the moving iron core 300d, while the other end of the push rod 300e penetrates the stationary iron core 300f. The push rod 300e can trigger the operating mechanism 200 under the action of the moving iron core 300d. The return spring 300g abuts between the push rod 300e and the stationary iron core 300f, which can reset the push rod 300e and the moving iron core 300d after actuation.
[0048] Specifically, when a short-circuit current occurs, the electromagnetic force on the moving iron core 300d (from the coil 300a, yoke 300c, etc.) is greater than the reaction force of the return spring 300g. The moving iron core 300d slides, causing the push rod 300e to move (while the return spring 300g is compressed), pushing the latch 210 of the operating mechanism 200. The steady state of the operating mechanism 200 is released, and a trip operation is performed. After the trip, the electromagnetic force disappears (coil 300a is de-energized), and the return spring 300g causes the moving iron core 300d and the push rod 300e to reset.
[0049] For the moving iron core 300d, it has a mating groove 300d1, with the opening of the groove 300d1 facing the stationary iron core 300f. One end of the push rod 300e abuts against the bottom of the groove 300d1. The push rod 300e has a stepped structure 300e1, which is located within the mating groove 300d1. The return spring 300g abuts against the stepped structure 300e1. This stepped structure 300e1 facilitates the assembly of the return spring 300g. Furthermore, the abutment structure of the mating groove 300d1 and the push rod 300e extending into the mating groove 300d1 facilitates the assembly of the moving iron core 300d and the push rod 300e, saving assembly steps (the two no longer need riveting to form a stable connection).
[0050] For push rod 300e, its dimension D1 in the first direction F1 is greater than that of moving iron core 300d in the first direction F1, and the dimension D2 of moving iron core 300d in the first direction F1 is greater than that of stationary iron core 300f in the first direction F1. This dimensional relationship ensures that the length of push rod 300e is sufficient to stably position one end within moving iron core 300d, thus contributing to structural stability. The greater dimension D2 of moving iron core 300d in the first direction F1 compared to that of stationary iron core 300f increases the size of moving iron core 300d, ensuring sufficient tripping force (because the electromagnetic force is sufficiently large during a short circuit; increasing the size of moving iron core 300d, i.e., increasing its mass, will improve kinetic energy and ensure sufficient tripping force).
[0051] For the moving iron core 300d, the moving iron core 300d always extends beyond the center line P in the first direction F1 of the sliding cavity. This structure allows the moving iron core 300d to have a sufficiently large first direction F1 dimension, which indirectly increases the size of the moving iron core 300d, also in order to ensure the tripping force (the reason is the same as above, and will not be repeated).
[0052] For the frame 300b, the side away from the opening has a sidewall 300b1, and the sidewall 300b1 has a through hole 300b2. The radial cross-sectional area of the through hole 300b2 is smaller than the radial cross-sectional area of the moving iron core 300d. This structure of the through hole 300b2 and the relationship of its cross-section ensure that one end of the frame 300b is open, reducing the air resistance during the movement of the moving iron core 300d (ensuring smoother movement), and also prevents the moving iron core 300d from falling out of the through hole 300b2.
[0053] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.
[0054] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.
Claims
1. A miniature circuit breaker, comprising a circuit breaker housing, an L-pole contact assembly, and an N-pole contact assembly, wherein the circuit breaker housing houses and separates the L-pole contact assembly and the N-pole contact assembly; characterized in that: The N-pole contact assembly includes an N-pole moving contact and an N-pole stationary contact. The N-pole stationary contact has a first contact surface for the N-pole moving contact to contact. It also includes an N-pole moving contact arc-starting angle, the first end of which is inclined and forms a Laval nozzle with the first contact surface. When the N-pole moving contact is in the broken position, the distance between the N-pole moving contact and the N-pole moving contact arc-starting angle is less than the distance between the N-pole moving contact and the N-pole stationary contact.
2. The miniature circuit breaker according to claim 1, characterized in that: It also includes an electromagnetic trip unit and an operating mechanism. The L-pole contact assembly includes an L-pole moving contact and an L-pole stationary contact. Both the L-pole moving contact and the N-pole moving contact are mounted on the operating mechanism and driven by the operating mechanism. The electromagnetic trip unit is used to trigger the operating mechanism to perform a tripping operation when a short circuit occurs in the line. The electromagnetic trip unit includes a coil, a frame, a magnetic yoke, a moving iron core, a push rod, a stationary iron core, and a reset spring. The moving iron core is slidably mounted in the frame, and the stationary iron core is fixed to the frame to seal the opening of the frame. One end of the push rod passes through the moving iron core and abuts against the moving iron core, while the other end of the push rod penetrates the stationary iron core to trigger the operating mechanism. The reset spring abuts between the push rod and the stationary iron core. The coil is wound on the frame, and the magnetic yoke is arranged around the perimeter of the frame.
3. A miniature circuit breaker according to claim 2, characterized in that: The moving iron core has a mating groove with the groove opening facing the stationary iron core, and one end of the push rod abuts against the bottom of the groove; the push rod has a stepped structure, which is located inside the mating groove, and the return spring abuts against the stepped structure.
4. A miniature circuit breaker according to claim 2, characterized in that: The dimension of the push rod in the first direction is larger than the dimension of the moving iron core in the first direction, and the dimension of the moving iron core in the first direction is larger than the dimension of the stationary iron core in the first direction; And / or, the skeleton has a sliding cavity, and the moving iron core always extends beyond the centerline of the sliding cavity in the first direction.
5. A miniature circuit breaker according to claim 2, characterized in that: The side of the skeleton away from the opening has a sidewall with a through hole. The radial cross-sectional area of the through hole is smaller than the radial cross-sectional area of the moving iron core.
6. A miniature circuit breaker according to claim 1, characterized in that: It also includes the first N-pole terminal, the second N-pole terminal, the first N-pole terminal, the moving N-pole contact, and the arc-leading angle of the moving N-pole contact, all of which are at the same potential. The second N-pole terminal and the stationary N-pole contact are at the same potential.
7. A miniature circuit breaker according to claim 6, characterized in that: The N-pole first terminal includes the N-pole first plate, and the N-pole first plate, the N-pole moving contact, and the N-pole moving contact arc-leading angle are connected by a soft connection to form an equipotential. And / or, the N-pole second terminal includes an N-pole second plate, and the N-pole second plate and the N-pole stationary contact are integrally formed to form equipotential, or are welded to form equipotential, or are formed through a soft connection to form equipotential.
8. A miniature circuit breaker according to claim 6 or 7, characterized in that: The N-pole moving contact arc-drawing angle includes a transition portion and a second end portion, the transition portion connecting the first end portion and the second end portion; in a first direction, the first end portion is located between the N-pole stationary contact and the N-pole first terminal; the first end portion gradually tilts towards the N-pole first terminal portion from the end connected to the transition portion to the end away from the transition portion, so as to form an inclined setting of the first end portion.
9. A miniature circuit breaker according to any one of claims 1-7, characterized in that: The N-pole moving contact arc-starting angle includes a transition portion and a second end portion, the transition portion connecting the first end portion and the second end portion; the N-pole stationary contact is provided with an N-pole stationary contact arc-starting angle, the first end of the N-pole stationary contact arc-starting angle being connected to the first contact surface; it also includes an arc-extinguishing chamber, the arc-extinguishing chamber being disposed above the second end portion, and the arc inlet of the arc-extinguishing chamber being adjacent to the second end of the N-pole stationary contact arc-starting angle.
10. A miniature circuit breaker according to claim 1, characterized in that: When the N-pole moving contact is in the broken position, there is an overlap between the N-pole moving contact and the first end in the second direction.