Magnetic trip device and electronic molded case circuit breaker

Abstract

This application discloses a magnetic tripping device and an electronic molded case circuit breaker in the field of power distribution circuit breaker technology. The magnetic tripping device includes an annular current transformer, a trip unit, a moving contact, a traction rod, and a connecting plate. The trip unit includes a shaft, a push rod, a reaction spring, and a stationary iron core. The moving contact is connected to the connecting plate, which passes through the inner ring hole of the current transformer. The trip unit is installed on the connecting plate inside the inner ring hole of the current transformer. The shaft passes through the connecting plate and is parallel to the annular surface of the current transformer. The stationary iron core is fixed perpendicularly to the shaft within the connecting plate within the inner ring hole of the current transformer. The push rod is rotated and fixed on the shaft through a connecting arm, causing the magnetic attraction surface to rotate around the shaft under the magnetic attraction force of the stationary iron core. The traction rod extends radially with a tripping arm. When the push rod rotates under the magnetic attraction force of the stationary iron core, the tripping end strikes the tripping arm, causing the traction rod to rotate. The reaction spring is disposed between the connecting plate and the magnetic attraction surface of the push rod. This solution solves the problem that the prior art cannot interrupt small-capacity short-circuit currents, achieving the technical effect of improving the breaking reliability.

Description

Technical Field

[0001] This application relates to the field of power distribution circuit breaker technology, specifically a magnetic tripping device and an electronic molded case circuit breaker. Background Technology

[0002] Electronic molded case circuit breakers (MCCBs) use control signals generated by an intelligent controller to control the trip unit, thus protecting the circuit. However, when a large short-circuit current flows through the circuit, the MCCB requires current detection and amplification in the main circuit, signal conversion, and triggering of the electronic trip unit. This slows down the fault disconnection process, and if the electronic trip unit malfunctions, it cannot effectively protect the circuit. Currently, magnetic trip units are typically added to MCCBs as protective trip units to achieve rapid short-circuit current disconnection. However, with increasingly smaller product requirements, large-capacity MCCBs cannot accommodate additional magnetic trip units due to size constraints. Therefore, they usually rely on moving contact linkage mechanisms to achieve this. The tripping protection function mainly relies on the electro-repulsive force generated when a short-circuit current passes through the contacts to drive the mechanism during the bouncing process. For example, patent document CN211788878U discloses a circuit breaker moving contact linkage tripping device, including a stationary contact, a moving contact, a mechanism, and a rotating shaft; the stationary contact is in contact with the moving contact, the moving contact is connected to the rotating shaft, and the rotating shaft is connected to the mechanism; the tripping device also includes a bouncing element and a traction rod, the rotating shaft is provided with a mating groove, part of the bouncing element extends into the mating groove and can rotate around the mating groove, the moving contact is provided with a driving groove, one end of the bouncing element extends into the driving groove and can slide in the driving groove, the end of the bouncing element away from the driving groove is connected to one end of the traction element, and the end of the traction element away from the bouncing element is connected to the mechanism. The above scheme is relatively complicated to assemble, and the shaft mold structure is also relatively complex. In addition, since large-capacity molded case circuit breakers generally need to have a large short-circuit withstand current, the contact pressure is relatively large. Typically, a single contact needs to be 30N to 50N. This structure requires a relatively large short-circuit current to operate reliably, which is not suitable for reliably breaking current for small-capacity short-circuit currents. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this application provides a magnetic tripping device and an electronic molded case circuit breaker to solve the problem that the existing technologies cannot interrupt small-capacity short-circuit currents.

[0004] To achieve the above objectives, this application provides the following technical solution:

[0005] A magnetic tripping device includes an annular current transformer, a tripping unit, a moving contact, a traction rod, and a connecting plate. The tripping unit includes a shaft, a push rod, a reaction spring, and a stationary iron core. The moving contact is fixedly connected to the connecting plate outside the inner ring hole of the current transformer. The connecting plate passes through the inner ring hole of the current transformer. The tripping unit is mounted on the connecting plate inside the inner ring hole of the current transformer. The shaft passes through the connecting plate and is parallel to the annular surface of the current transformer. The stationary iron core is fixed perpendicularly to the shaft within the connecting plate within the range of the inner ring hole of the current transformer. The push rod includes a magnetic attraction surface and a tripping end. The push rod is rotated and fixed to the shaft by connecting arms bent on both sides towards the connecting plate, causing the magnetic attraction surface to rotate around the shaft under the magnetic attraction of the stationary iron core. The traction rod is parallel to the shaft and has a tripping arm extending radially at a corresponding position of the push rod's tripping end. When the push rod rotates under the magnetic attraction of the stationary iron core, the tripping end strikes the tripping arm, causing the traction rod to rotate. The reaction spring is disposed between the connecting plate and the magnetic attraction surface of the push rod and is compressed when the push rod rotates under the magnetic attraction of the stationary iron core.

[0006] Preferably, the current transformer uses a square ring.

[0007] Preferably, the connecting plate includes a first connecting plate and a second connecting plate, the second connecting plate being connected to the moving contact, and the surfaces of the first connecting plate and the second connecting plate overlapping.

[0008] Preferably, the stationary iron core uses screws, and the first connecting plate and the second connecting plate have screw holes perpendicular to the plate surface at the overlapping area of ​​the plate surface. The first connecting plate and the second connecting plate are fixedly connected by screws passing through the screw holes.

[0009] Preferably, the connecting arm has a second hole, and the connecting arm is rotatably fixed to the shaft through the second hole.

[0010] Preferably, the magnetic surface of the push rod is provided with a boss facing the connecting plate, and the reaction spring is fixed in the direction of the push rod by the boss extending into the reaction spring.

[0011] Preferably, the surface of the second connecting plate facing the push rod is provided with a recess, and the reaction spring extends into the recess of the second connecting plate at one end facing the connecting plate for fixation.

[0012] Preferably, the second connecting plate has a through first hole on its side, and the shaft passes through the first hole.

[0013] Preferably, two screws are used.

[0014] Based on the same inventive concept, this application also discloses an electronic molded case circuit breaker, including an operating mechanism and the aforementioned magnetic tripping device. The traction rod is mounted on the operating mechanism, and the tripping end of the push rod strikes the tripping arm, causing the traction rod to rotate and drive the operating mechanism to trip the circuit breaker.

[0015] Compared with the prior art, the advantages of this solution are as follows: The magnetic tripping device and electronic molded case circuit breaker of this application use screws that fix the first and second connecting plates as static iron cores and design a reaction spring and a push rod with a magnetic attraction surface. When there is a short circuit current in the line, the backup protection device has a short circuit current greater than the set threshold. The screw and the push plate form magnets with opposite polarities. Utilizing the principle of attraction between opposite poles of magnets, the electromagnetic force generated by the magnet is greater than the reaction force of the compression spring. The two attract each other, making it impossible for a small-capacity short circuit current to reliably interrupt the current. The magnetic tripping scheme of this solution is reliable and has a wide range of applications. Attached Figure Description

[0016] Figure 1 This is a three-dimensional structural diagram of an embodiment of the magnetic tripping device of this solution;

[0017] Figure 2 This is a three-dimensional structural diagram of a hidden transformer explosion in an embodiment of the magnetic tripping device of this scheme;

[0018] Figure 3 This is a three-dimensional structural diagram of an embodiment of the second connecting plate of this solution;

[0019] Figure 4 This is a three-dimensional structural diagram of one embodiment of the push rod in this solution;

[0020] Figure 5 This is a three-dimensional schematic diagram showing the installation of the first connecting plate and the second connecting plate in one embodiment of the magnetic release device of this scheme.

[0021] Figure 6 This is a three-dimensional structural diagram of the internal structure of an embodiment of the electronic molded case circuit breaker of this solution;

[0022] Figure 7 This is a three-dimensional structural diagram of the position of the trip unit, two connecting plates, and traction rod in the tripped state according to one embodiment of the present solution;

[0023] Figure 8 This is a three-dimensional structural diagram of the trip unit, two connecting plates, and traction rod in the normal state of one embodiment of this solution;

[0024] Figure 9 This is a three-dimensional structural diagram of the installation of the first connecting plate and the second connecting plate in one embodiment of the present solution, viewed from the perspective of the first connecting plate.

[0025] Among them, 11-shaft, 12-push rod, 121-boss, 122-second hole, 13-reaction spring, 2-operating mechanism, 21-traction rod, 31-moving contact, 32-first connecting plate, 33-second connecting plate, 331-recess, 332-first hole, 34-screw. Detailed Implementation

[0026] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0027] A magnetic tripping device includes an annular current transformer, a tripping device, a moving contact 31, and a traction rod 21 on a circuit breaker operating mechanism 2. The tripping device includes a shaft 11, a push rod 12, and a reaction spring 13. The push rod 12 includes a magnetic attraction surface and a tripping end.

[0028] One end of the reaction spring 13 is placed in the recess 331 of the second connecting plate 33. The push rod 12 is placed on the second connecting plate 33. The other end of the reaction spring 12 is limited to the boss 121 on the magnetic surface of the push rod 12. The shaft 11 passes through the push rod 12 and the second connecting plate 33 respectively. Under the action of the reaction spring 13, the push rod 12 is limited to the second connecting plate 33.

[0029] The moving contact assembly, including the moving contact 31, is inserted into the current transformer, and the first connecting plate 32 and the second connecting plate 33 are fastened together by two screws 34.

[0030] When a short-circuit current occurs in the circuit, and the backup protection device experiences a short-circuit current exceeding the set threshold, push rod 12 is magnetized. Screw 34 in the connecting plate acts as a stationary iron core, forming a magnet with opposite polarity to push rod 12. When the electromagnetic attraction generated by the two magnets exceeds the reaction force of the return spring 13, they attract each other, compressing the return spring 13 into a compression spring. Push rod 12 rotates around shaft 11, and the tripping end of push rod 12 pushes the tripping arm of traction rod 21. Traction rod 21 then drives the operating mechanism 2, thereby tripping the circuit breaker. After tripping, push rod 12 returns to its initial position under the action of the reaction force of return spring 13.

[0031] In this embodiment, the current transformer uses a square ring shape, but other ring shapes such as circular rings can also be used. A second hole 122 is formed on the connecting arm of the push rod 12, and the connecting arm is rotatably fixed to the shaft 11 through the second hole 122. Alternatively, a shaft cap or other form of fixation can be used. A through hole 332 is formed on the side of the second connecting plate 33, and the shaft 11 passes through the first hole 332. The shaft 11 can also be configured in other ways, such as by setting a small coaxial protruding cylinder on the side of the second connecting plate 33.

[0032] The reaction spring 13 is fixed using a concave-convex method. Specifically, the magnetic surface of the push rod 12 has a boss 121 facing the connecting plate, and the reaction spring 13 is fixed to the push rod 12 using the boss 121 extending into it. The surface of the second connecting plate 33 facing the push rod 12 has a recess 331, and the end of the reaction spring 13 facing the connecting plate extends into the recess 331 of the second connecting plate 33 for fixation. Alternatively, a boss can be provided on the second connecting plate 33, and a recess or hook-and-loop method can be used oppositely, with the recess on the magnetic surface of the push rod 12 facing the opposite direction.

[0033] In this specification, the schematic diagrams in the accompanying drawings highlight the main features and key parts, and details are appropriately simplified or omitted. Therefore, they do not represent actual scale and size relationships. The terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples. Furthermore, 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.

[0034] The above description is only a preferred embodiment of the present solution, but the scope of protection claimed by the present solution is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in this application, based on the technical solution and inventive concept of this application, should be included within the scope of protection of this application.

Claims

1. A magnetic tripping device, comprising an annular current transformer, characterized in that: It also includes a trip unit, a moving contact (31), a traction rod (21), and a connecting plate. The trip unit includes a shaft (11), a push rod (12), a reaction spring (13), and a stationary iron core. The moving contact (31) is fixedly connected to the connecting plate outside the inner ring hole of the transformer. The connecting plate passes through the inner ring hole of the transformer. The trip unit is installed on the connecting plate inside the inner ring hole of the transformer. The shaft (11) passes through the connecting plate and is parallel to the annular surface of the transformer. The stationary iron core is fixed perpendicularly to the shaft within the connecting plate within the inner ring hole of the transformer. The push rod (12) includes a magnetic suction surface and an end. The release end of the push rod (12) is fixed on the shaft (11) by the connecting arms that bend on both sides toward the connecting plate, so that the magnetic attraction surface rotates around the shaft (11) under the magnetic attraction force of the static iron core. The traction rod (21) is parallel to the shaft (11) and has a release arm that extends radially at the corresponding position of the release end of the push rod (12). When the push rod (12) rotates under the magnetic attraction force of the static iron core, the release end strikes the release arm to make the traction rod (21) rotate. The reaction spring (13) is set between the connecting plate and the magnetic attraction surface of the push rod (12) and is compressed when the push rod (12) rotates under the magnetic attraction force of the static iron core.

2. The magnetic tripping device according to claim 1, characterized in that: The current transformer uses a square ring.

3. The magnetic tripping device according to claim 1, characterized in that: The connecting plate includes a first connecting plate (32) and a second connecting plate (33), the second connecting plate (33) is connected to the moving contact (31), and the surfaces of the first connecting plate (32) and the second connecting plate (33) overlap.

4. The magnetic tripping device according to claim 3, characterized in that: The stationary iron core is fixedly connected by screws (34). The first connecting plate (32) and the second connecting plate (33) have screw holes perpendicular to the plate surface at the joint. The first connecting plate (32) and the second connecting plate (33) are fixedly connected by screws (34) passing through the screw holes.

5. The magnetic release device according to claim 1, characterized in that: The connecting arm has a second hole (122), and the connecting arm is rotatably fixed on the shaft (11) through the second hole (122).

6. The magnetic tripping device according to claim 1, characterized in that: The push rod (12) has a boss (121) on its magnetic attraction surface facing the connecting plate, and the reaction spring (13) is fixed in the direction of the push rod (12) by the boss (121) extending into the reaction spring (13).

7. The magnetic tripping device according to claim 3, characterized in that: The second connecting plate (33) has a recess (331) on its surface facing the push rod (12), and the reaction spring (13) extends into the recess (331) of the second connecting plate (33) and is fixed thereto.

8. The magnetic tripping device according to claim 3, characterized in that: The second connecting plate (33) has a through hole (332) on its side, and the shaft (11) passes through the first hole (332).

9. The magnetic tripping device according to claim 4, characterized in that: Two screws (34) are used.

10. An electronic molded case circuit breaker, comprising an operating mechanism (2), characterized in that: It also includes the magnetic tripping device according to any one of claims 1 to 9, wherein the traction rod (21) is disposed on the operating mechanism (2), and the tripping end of the push rod (12) strikes the tripping arm to cause the traction rod (21) to rotate, thereby driving the operating mechanism (2) to trip the circuit breaker.

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