Molded case circuit breaker

Abstract

The utility model discloses a molded case circuit breaker, and the molded case circuit breaker is characterized in that a first blind hole is in a special shape, and the hole side wall of the first blind hole comprises a first hole side wall and a second hole side wall; the minimum gap d between the side wall of the second hole and the screw head is larger than or equal to 0.5 mm. The minimum gap between the side wall of the first hole and the screw head is D, and D-d is at least 1.5 mm; the first hole side wall is closer to the first side wall than the second hole side wall; the power distribution cabinet has the advantage of being better in creepage distance.

Description

Technical Field

[0001] This application relates to the field of low-voltage electrical appliances, specifically a molded case circuit breaker. Background Technology

[0002] like Figures 9-10 As shown, the molded case circuit breaker has a first terminal plate, and the stationary contact is fixed to the first terminal plate. The first terminal plate is fastened to the base with screws 100. Specifically, the first terminal plate is installed on the front of the base, and the screws 100 are driven into the blind holes 120 on the back of the base for fixing. After fixing, a base plate 130 is embedded in the back of the base to cover all screw holes.

[0003] like Figure 10 As shown, under ideal conditions, the creepage distance from screw 110 to the blind hole opening is calculated as follows: a + thickness of the screw head (a) + thickness of the washer (b) + part of the bottom of the blind hole groove (c) + sidewall of the blind hole (d).

[0004] However, in reality, the closest distance from the sidewall of the blind hole to the screw head (or the radius of the blind hole is greater than the radius of the screw head) is about 0.5mm. This distance is too small, which will cause the electric current of the screw head to creep directly onto the sidewall of the blind hole. That is, the actual creepage distance is as shown in Figure 10, which is part of the sidewall E of the blind hole.

[0005] Through extensive research, the inventors discovered that such a small blind hole structure (the closest distance from the sidewall of the blind hole to the screw head is about 0.5mm) results in insufficient creepage distance, making it easy for electricity to flow out from the first side of the base plate near the first terminal plate (this sidewall 130 is the sidewall of the blind hole closest to the base plate, and the part of the sidewall of the blind hole near this sidewall is easy to flow out from this sidewall), leading to grounding breakdown.

[0006] Therefore, it is essential to design a new structure that reduces the likelihood of screws breaking down to ground. Summary of the Invention

[0007] In view of this, the purpose of this application is to overcome the shortcomings of the prior art and to provide a molded case circuit breaker.

[0008] This application provides: a molded case circuit breaker, comprising a base, a base plate, a first terminal plate, and a first fastening screw; a first blind hole corresponding to the first fastening screw is provided on the back of the base, and a first through hole is provided on the bottom wall of the first blind hole; the first terminal plate is located on the front of the base, and the first fastening screw is connected to the first terminal plate through the first through hole to fix it to the base, with the screw head of the first fastening screw located in the first blind hole; the base plate is at least partially embedded in the back of the base, covering all the first blind holes, and the base plate has a first sidewall, which is the sidewall of the base plate closest to the first blind hole; wherein, the shape of the first blind hole is irregular, and the sidewall of the first blind hole includes a first sidewall and a second sidewall; the minimum gap between the second sidewall and the screw head is d, where d ≥ 0.5 mm; the minimum gap between the first sidewall and the screw head is D, where Dd is at least 1.5 mm; the first sidewall is closer to the first sidewall than the second sidewall.

[0009] In some embodiments of this application, the orthographic projection shape of the second hole sidewall on the bottom wall of the first blind hole is a second shape, and the orthographic projection shape of the first hole sidewall on the bottom wall of the first blind hole is a first shape; the second shape is an arc, and the first shape is an arc or two or more continuous straight lines.

[0010] In some embodiments of this application, a third hole sidewall is also included, connecting the second hole sidewall and the first hole sidewall. There are two third hole sidewalls. The orthographic projection shape of the first hole sidewall on the bottom wall of the first blind hole is a first arc, the orthographic projection shape of the second hole sidewall on the bottom wall of the first blind hole is a second arc, and the orthographic projection shape of the third hole sidewall on the bottom wall of the first blind hole is a straight line. The two ends of the first arc and the second arc are respectively connected by a straight line.

[0011] In some embodiments of this application, a groove is provided on the back of the base, and the base plate is at least partially embedded in the back of the base through the groove; at least one disassembly groove is provided on the side of the groove, and the disassembly groove communicates with the groove.

[0012] In some embodiments of this application, the first terminal block includes a first wiring segment and a first fixing segment, and a first fastening screw is fastened to the first fixing segment; in the length direction of the base, a first side wall is located between the first wiring segment and the first fixing segment.

[0013] In some embodiments of this application, a positioning rib is provided on the front side of the base, and a positioning groove is provided on the first terminal plate; the positioning groove and the positioning rib form a positioning fit; the size of the positioning rib gradually increases from the end of the positioning rib away from the front side of the base to the end closer to the front side of the base.

[0014] In some embodiments of this application, a second terminal block, a conductive block, and a backup protector are also included; the backup protector includes a U-shaped bracket, a U-shaped yoke, and a U-shaped armature, the U-shaped bracket is located inside the U-shaped yoke and both are fixed to the conductive block by a first fastener; the U-shaped armature and the U-shaped bracket are hinged together, and the U-shaped armature and the U-shaped yoke together form a frame-shaped space, and the conductive block is at least partially inserted into the frame-shaped space.

[0015] In some embodiments of this application, the conductive block includes a moving contact welding section and a first connecting section. The moving contact welding section is used for soft connection welding of the moving contact. The moving contact welding section passes through the frame-shaped space. It also includes a second fastening screw, which passes through the base, U-shaped magnetic yoke, and U-shaped bracket from the back of the base and is fastened to the moving contact welding section. A second blind hole for accommodating the screw head of the second fastening screw is opened on the back of the base, and the bottom plate covers all the second blind holes.

[0016] In some embodiments of this application, the first connecting section has a protruding portion that extends beyond the lower surface of the moving contact welding section; at least a portion of the U-shaped magnetic yoke and the U-shaped bracket are located on one side of the protruding portion, the U-shaped magnetic yoke abuts against the protruding portion, and the lower part of the U-shaped magnetic yoke and the U-shaped bracket does not extend beyond the protruding portion.

[0017] In some embodiments of this application, the second terminal block includes a second wiring segment and a second connecting segment; the second connecting segment and the first connecting segment are fastened together by a second fastener; it also includes a current transformer, which is sleeved at the connection between the second connecting segment and the first connecting segment, and the housing of the current transformer forms a limiting fit with the second connecting segment.

[0018] The advantages of this application compared to the prior art are:

[0019] By adopting the above structure, the existing circular blind hole is replaced with an irregular blind hole. In particular, the minimum clearance between the first hole sidewall, which is closest to the first sidewall (the sidewall closest to the first blind hole among all the sidewalls of the base plate), and the screw head is D. This clearance is at least 1.5mm larger than d (d can be understood as the clearance in the prior art). This increased clearance ensures that the creepage distance from the screw head to the opening of the first blind hole is increased (the specific creepage distance is the distance from the screw head to the bottom wall of the blind hole + D + the depth of the blind hole). This ensures the creepage distance and prevents electricity from flowing out of the base plate and causing grounding. 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 bottom schematic diagram of the molded case circuit breaker according to an embodiment of this application is shown;

[0022] Figure 2 This application shows a cross-sectional view and a partial enlarged view of the fastening point between the base and the first terminal plate in a molded case circuit breaker according to an embodiment of the present application;

[0023] Figure 3 A schematic diagram of the back of the base in a molded case circuit breaker according to an embodiment of this application is shown;

[0024] Figure 4 A schematic diagram of the front of the base in the molded case circuit breaker according to an embodiment of this application is shown;

[0025] Figure 5 This paper shows a schematic diagram of the orthographic projection of the first blind hole and the first fastening screw in a molded case circuit breaker according to an embodiment of this application.

[0026] Figure 6 A schematic diagram of the current transformer, backup protector, conductive block and second terminal block in the molded case circuit breaker of the present application embodiment is shown;

[0027] Figure 7 A schematic diagram of the backup protector and conductive block in a molded case circuit breaker according to an embodiment of this application is shown;

[0028] Figure 8 A schematic diagram of the conductive block and the second terminal block in a molded case circuit breaker according to an embodiment of this application is shown;

[0029] Figure 9 A schematic diagram of the bottom of a molded case circuit breaker in the present art is shown;

[0030] Figure 10 The diagram shows a cross-sectional view of the terminal block and screw fastening point in the prior art, as well as enlarged views of the ideal and actual states. Detailed Implementation

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first and second features are in direct contact, or that the first and second features are in indirect contact 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 indicates 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 indicates that the first feature is at a higher horizontal level than the second feature.

[0036] The level of feature one is less than that of feature two. Example

[0037] like Figures 1-8 As shown, an embodiment of this application is a molded case circuit breaker.

[0038] This type of molded case circuit breaker includes the circuit breaker housing, operating mechanism, moving contact structure, stationary contact structure, and so on.

[0039] The circuit breaker housing includes a cover, a base 100, and a base plate 101. Since this application mainly focuses on improving some components on the base 100, the cover is common knowledge in the art and will not be described in detail here.

[0040] Both the first terminal block 300 and the second terminal block 400 are fixed to the base 100. The first terminal block 300 is an integral part of the stationary contact and is used to connect to external circuitry. The second terminal block 400 is electrically connected to the moving contact; this electrical connection is a flexible connection, and the second terminal block 400 is also used to connect to external circuitry. The connection and disconnection of the circuit can be achieved by the contact and separation of the moving and stationary contacts.

[0041] Here, the first terminal plate 300 is fixed to the base 100 by the first fastening screw 310. Specifically, a first blind hole 110 is provided on the back of the base 100, and a first through hole 120 is provided on the bottom wall 110a of the first blind hole 110. The first terminal plate 300 is located on the front of the base 100, and the first fastening screw 310 is connected to the first terminal plate 300 through the first through hole 120 to fix it to the base 100. After tightening, the screw head 310a of the first fastening screw 310 is located in the first blind hole 110. Here, each first terminal plate 300 is fastened by two first fastening screws 310.

[0042] The base plate 101 is embedded in the back of the base 100, covering all the first blind holes 110. There are many ways to fix the base plate 101 to the base 100, such as adhesive, snap-fit, or screw connection.

[0043] Regarding the base plate 101, it has four sidewalls, among which the first sidewall 1011 is the sidewall closest to the first blind hole 110. The first blind hole 110 is irregularly shaped, comprising a bottom wall 110a and hole sidewalls, which surround the bottom wall 110a to form the blind hole. Here, the hole sidewalls include a first hole sidewall 110b and a second hole sidewall 110c, with the first hole sidewall 110b being closer to the first sidewall 1011 than the second hole sidewall 110c. In this embodiment, the minimum clearance between the second hole sidewall 110c and the screw head 310a (of the first fastening screw 310) is d, where d is 0.75mm; the minimum clearance between the first hole sidewall 110b and the screw head 310a is D, where D is 2.25mm. Of course, this is not a limitation; as long as d is at least ≥ 0.5mm and Dd is at least 1.5mm, it is acceptable.

[0044] By changing the existing circular blind hole to an irregular blind hole, especially the first hole sidewall 110b which is closest to the first sidewall 1011 (the sidewall closest to the first blind hole 110 among all the sidewalls of the base plate 101), the minimum gap between it and the screw head 310a is D, which is at least 1.5mm larger than d (d can be understood as the gap in the prior art). This increased gap ensures that the creepage distance from the screw head 310a to the opening of the first blind hole 110 is increased (the specific creepage distance is the distance from the screw head 310a to the bottom wall 110a of the blind hole + D + the depth of the blind hole), thus ensuring the creepage distance and preventing electricity from flowing out of the base plate 101 and causing a breakdown to ground.

[0045] Here, the first terminal block 300 includes a first wiring segment 300a and a first fixing segment 300b, and a first fastening screw 310 is fastened to the first fixing segment 300b. In the length direction of the base 100, a first side wall 1011 is located between the first wiring segment 300a and the first fixing segment 300b.

[0046] Regarding the shapes of the first hole sidewall 110b and the second hole sidewall 110c, taking their orthographic projections onto the bottom wall 110a of the first blind hole 110 as an example, the orthographic projection shape of the second hole sidewall 110c onto the bottom wall 110a of the first blind hole 110 is the second shape. The orthographic projection shape of the first hole sidewall 110b onto the bottom wall 110a of the first blind hole 110 is the first shape. As a preferred embodiment, both the first and second shapes are circular arcs, with the radius of the second shape being smaller than the radius of the first shape. Furthermore, the two ends of the first and second circular arcs are connected by a straight line, which is the orthographic projection shape of the third hole sidewall onto the bottom wall 110a of the first blind hole 110. In other words, a third hole sidewall connects the second hole sidewall 110c and the first hole sidewall 110b.

[0047] Of course, in addition to this, the first shape can also be two or more consecutive straight lines. For example, the orthographic projection shape of the first blind hole 110 is a composite shape of a circle and other shapes (triangles, rectangles, squares, or polygons).

[0048] For the base plate 101, to facilitate disassembly, a groove 101a is provided on the back of the base 100, through which the base plate 101 is embedded. A disassembly groove 101b is provided on the side of the groove 101a, and the disassembly groove 101b communicates with the groove 101a, so that fingers or tools can be inserted into the disassembly groove 101b to pry open the base plate 101, which is convenient for disassembly and assembly.

[0049] A positioning rib 100a is provided on the front side of the base 100, and a positioning groove 300c is provided on the first terminal plate 300. The positioning groove 300c is specifically located at the connection between the first wiring section 300a and the first fixing section 300b. This positioning groove 300c and the positioning rib 100a form a positioning fit, which facilitates the assembly of the first terminal plate 300 and the alignment of the first fastening screw 310. Here, the size of the positioning rib 100a is not constant, but gradually increases from the end furthest from the front side of the base 100 to the end closest to the front side of the base 100. This structure further facilitates the alignment and sliding of the first terminal plate 300 into the base 100.

[0050] The second terminal block 400 is fixed to the base 100 by fixing the conductive block 410. Here, the conductive block 410 is fastened to the base 100 by the second fastening screw 320. The back of the base 100 also has a second blind hole 130 for receiving the screw head of the second fastening screw 320. The base plate 101 shields all the second blind holes 130. Since the distance between the sidewall of the base plate 101 and the second blind hole 130 is relatively greater than that of the first blind hole 110 in this field, the creepage distance is sufficient, and the irregular structure of the first blind hole 110 is not required. Of course, if the distance between the sidewall of the second blind hole 130 and the base plate 101 is small and the creepage distance is insufficient, a similar structural design to the first blind hole 110 can also be used.

[0051] Here, the conductive block 410 is a conductive component that connects the second terminal block 400 and the moving contact (soft wire).

[0052] A backup protector is provided on the conductive block 410. Specifically, the backup protector includes a U-shaped bracket 500, a U-shaped magnetic yoke 510, a U-shaped armature 530, a rotating shaft, and a return spring. The U-shaped bracket 500 is located inside the U-shaped magnetic yoke 510, and both are fixed to the conductive block 410 by a first fastener 540, which is a screw, but rivets can also be used. The U-shaped armature 530 and the U-shaped bracket 500 are hinged together by the rotating shaft, and the U-shaped armature 530 and the U-shaped magnetic yoke 510 together form a frame-shaped space, in which the conductive block 410 partially passes. The return spring is a torsion spring sleeved on the rotating shaft, with one end abutting against the U-shaped armature 530 and the other end connected to a hook on the U-shaped bracket 500. When an abnormality occurs in the line, the current flowing through the conductive block 410 increases, causing the attraction of the U-shaped magnetic yoke 510 to the U-shaped armature 530 to be greater than the force of the reset spring. The U-shaped armature 530 rotates to trigger the operating mechanism, thereby tripping the circuit breaker.

[0053] This structure allows the backup protector to be directly fixed to the conductive block 410, forming a mounting assembly, which facilitates the installation and positioning of the backup protector.

[0054] The conductive block 410 includes a moving contact welding section 410a and a first connecting section 410b. The moving contact welding section 410a is used for flexible welding of the moving contact. Furthermore, the moving contact welding section 410a is inserted into the frame-shaped space; that is, the U-shaped bracket 500 and the U-shaped magnetic yoke 510 are both fixed to the moving contact welding section 410a by the first fastener 540. The second fastening screw 320 also passes sequentially through the base 100, the U-shaped magnetic yoke 510, and the U-shaped bracket 500 and is fastened to the moving contact welding section 410a.

[0055] This structure can effectively ensure the stable installation of the backup protector.

[0056] The first connecting section 410b has a protruding portion 410c that extends beyond the lower surface of the moving contact welding section 410a. This protruding portion 410c creates a receiving groove between one side of it and the lower surface of the moving contact welding section 410a, and a portion of the U-shaped yoke 510 and the U-shaped support 500 is located on one side of the protruding portion 410c (i.e., within the receiving groove). Furthermore, the lower parts of the U-shaped yoke 510 and the U-shaped support 500 are lower than (and do not exceed) the protruding portion 410c, and the U-shaped yoke 510 abuts against the side surface of the protruding portion 410c. This design of the protruding portion 410c ensures that the U-shaped yoke 510 abuts against it, making the backup protector securely and stably fastened, guaranteeing a stable current flow direction, and providing relatively stable protection performance.

[0057] The second terminal block 400 includes a second wiring segment 400a and a second connecting segment 400b. The second connecting segment 400b is fastened to the first connecting segment 410b by a second fastener 430, which is also a screw. This fastening method ensures the installation stability of the second terminal block 400 by means of the fastening of the conductive block 410 to the base 100 (the fastening of the second fastening screw 320).

[0058] Here, the current transformer 600 is fitted at the connection between the second connecting section 400b and the first connecting section 410b. The current transformer 600 can be a metering current transformer 600, a protection current transformer 600, or a sampling current transformer 600 for switching power supply functions. The housing of the current transformer 600 has a limiting protrusion 610, which forms a limiting engagement with a portion of the second connecting section 400b, ensuring the stability of the entire assembly.

[0059] For circuit breakers, they can be 1-4 pole circuit breakers. Although the above only introduces one first terminal board 300, second terminal block 400, etc., the actual number of parts such as the first terminal board 300, second terminal block 400, etc. is related to the number of poles. When it is a multi-pole circuit breaker, it can contain multiple parts such as the first terminal board 300, second terminal block 400, etc.

[0060] 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.

[0061] 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 molded case circuit breaker, comprising a base, a base plate, a first terminal plate, and a first fastening screw; a first blind hole corresponding to the first fastening screw is formed on the back of the base, and a first through hole is formed on the bottom wall of the first blind hole; the first terminal plate is located on the front of the base, and the first fastening screw is connected to the first terminal plate through the first through hole to fix it to the base, the screw head of the first fastening screw being located in the first blind hole; the base plate is at least partially embedded in the back of the base, covering all the first blind holes, and the base plate has a first sidewall, which is the sidewall of the base plate closest to the first blind hole; characterized in that: The first blind hole has an irregular shape, and the sidewall of the first blind hole includes a first sidewall and a second sidewall; the minimum gap between the second sidewall and the screw head is d, where d ≥ 0.5 mm; the minimum gap between the first sidewall and the screw head is D, where Dd is at least 1.5 mm; the first sidewall is closer to the first sidewall than the second sidewall.

2. A molded case circuit breaker according to claim 1, characterized in that: The orthographic projection shape of the second hole sidewall onto the bottom wall of the first blind hole is the second shape, and the orthographic projection shape of the first hole sidewall onto the bottom wall of the first blind hole is the first shape; the second shape is an arc, and the first shape is an arc or two or more continuous straight lines.

3. A molded case circuit breaker according to claim 1, characterized in that: It also includes a third hole sidewall connecting the second hole sidewall and the first hole sidewall, and there are two third hole sidewalls; The orthographic projection of the first hole sidewall onto the bottom wall of the first blind hole is a first circular arc, the orthographic projection of the second hole sidewall onto the bottom wall of the first blind hole is a second circular arc, and the orthographic projection of the third hole sidewall onto the bottom wall of the first blind hole is a straight line. The two ends of the first and second circular arcs are respectively connected by a straight line.

4. A molded case circuit breaker according to claim 1, characterized in that: The back of the base has a groove, and the base plate is at least partially embedded in the back of the base through the groove; at least one disassembly groove is provided on the side of the groove, and the disassembly groove is connected to the groove.

5. A molded case circuit breaker according to claim 1, characterized in that: The first terminal block includes a first wiring segment and a first fixing segment, and a first fastening screw is fastened to the first fixing segment; in the length direction of the base, the first side wall is located between the first wiring segment and the first fixing segment.

6. A molded case circuit breaker according to claim 1, characterized in that: The base has a positioning rib on its front side, and a positioning groove is provided on the first terminal plate; the positioning groove and the positioning rib form a positioning fit; the size of the positioning rib gradually increases from the end of the positioning rib away from the front side of the base to the end closer to the front side of the base.

7. A molded case circuit breaker according to claim 1, characterized in that: It also includes a second terminal block, a conductive block, and a backup protector; the backup protector includes a U-shaped bracket, a U-shaped yoke, and a U-shaped armature, the U-shaped bracket is located inside the U-shaped yoke and both are fixed to the conductive block by a first fastener; the U-shaped armature and the U-shaped bracket are hinged together, and the U-shaped armature and the U-shaped yoke together form a frame-shaped space, and the conductive block is at least partially inserted in the frame-shaped space.

8. A molded case circuit breaker according to claim 7, characterized in that: The conductive block includes a moving contact welding section and a first connecting section. The moving contact welding section is used for soft connection welding of the moving contact. The moving contact welding section passes through the frame-shaped space. It also includes a second fastening screw, which passes through the base, U-shaped magnetic yoke, and U-shaped bracket from the back of the base and is fastened to the moving contact welding section. A second blind hole is opened on the back of the base to accommodate the screw head of the second fastening screw, and the bottom plate covers all the second blind holes.

9. A molded case circuit breaker according to claim 8, characterized in that: The first connecting section has a protruding portion that extends beyond the lower surface of the moving contact welding section; at least a portion of the U-shaped magnetic yoke and the U-shaped bracket are located on one side of the protruding portion, the U-shaped magnetic yoke abuts against the protruding portion, and the lower part of the U-shaped magnetic yoke and the U-shaped bracket does not extend beyond the protruding portion.

10. A molded case circuit breaker according to claim 8, characterized in that: The second terminal block includes a second wiring segment and a second connecting segment; the second connecting segment is fastened to the first connecting segment by a second fastener; it also includes a current transformer, which is sleeved at the connection between the second connecting segment and the first connecting segment, and the housing of the current transformer forms a limiting fit with the second connecting segment.

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