A contact system for a low voltage circuit breaker

Abstract

The application relates to a contact system of a low-voltage circuit breaker, comprising a moving contact system and a static contact system, the moving contact system comprising a plurality of moving contact pieces (3), a moving contact point (4), a contact support (5), a first rotating shaft (7) and a contact spring (8), the moving contact point (4) being arranged on the moving contact piece (3), the plurality of moving contact pieces (3) being connected side by side on the first rotating shaft (7) and being capable of rotating around the first rotating shaft (7), the first rotating shaft (7) being arranged on the contact support (5), and the contact spring (8) being arranged on the contact support (5); the plurality of moving contact pieces (3) comprising middle sequence moving contact pieces and two side moving contact pieces, wherein the middle sequence moving contact pieces are moving contact pieces provided with an arc leading angle (305). Compared with the prior art, the application has the advantages of fast arc leading speed, high breaking capacity, strong structural stability and realization of spring installation positioning adjustment.

Description

Technical Field

[0001] This invention relates to the field of low-voltage electrical technology, and more specifically to a contact system for a low-voltage circuit breaker. Background Technology

[0002] The contact system of a circuit breaker bears the crucial task of normally connecting, disconnecting, and connecting short-circuit currents. Therefore, the designed contact system must possess sufficient dynamic and thermal stability, resistance to welding, wear resistance, and temperature rise control. With market demand, universal circuit breakers are increasingly used in the new energy sector, such as photovoltaic and wind power. However, the original designs of the moving contact system in the industry typically have a limited number of parallel connecting branches, and during assembly, the contact springs inevitably experience installation position deviations. Furthermore, frequent opening and closing during operation can cause the contact springs to deviate from their normal operating positions. To ensure reliable disconnection and connection of short-circuit currents and minimize temperature rise, maintaining and guaranteeing the contact pressure of the moving contact system and reducing its operating temperature rise are crucial.

[0003] Utility model patent CN207587676U discloses a moving contact of a circuit breaker, including a contact support, a rotating shaft, a moving contact piece, a flexible connection, and a moving contact busbar. The rotating shaft is rotatably mounted on the contact support. One end of the flexible connection is electrically connected to the moving contact piece, and the other end is electrically connected to the moving contact busbar. The patent also includes a moving contact bracket, which includes multiple spaced-apart support grids. The support grids are staggered from the moving contacts. A first connecting part and a second connecting part are respectively provided on both sides of the moving contact bracket for fixing to each support grid. Due to the addition of the contact bracket, the gap between each moving contact piece is ensured by the support grids fixed on both sides, while also ensuring the strength of the support grids. This allows the circuit breaker to meet the requirements of high short-term withstand capability, high breaking capacity, and miniaturization. However, the positioning and adjustment of the spring during installation are difficult, and the arc ignition speed of the moving contact is relatively slow. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a contact system for a low-voltage circuit breaker with a faster arc ignition speed.

[0005] The objective of this invention can be achieved through the following technical solution: A contact system for a low-voltage circuit breaker, comprising a moving contact system and a stationary contact system. The moving contact system includes a plurality of moving contact plates, a moving contact, a contact support, a first rotating shaft, and a contact spring. The moving contact is located on the moving contact plate. The plurality of moving contact plates are connected side-by-side to the first rotating shaft through a first shaft hole and can rotate around the first rotating shaft. The first rotating shaft is mounted on the contact support, and the contact spring is mounted on the contact support. The plurality of moving contact plates include a middle sequence of moving contact plates and two side moving contact plates, wherein the middle sequence of moving contact plates is a moving contact plate with an arc-inducing angle.

[0006] The moving contact piece is of the Venturi nozzle type, with the two moving contact pieces on both sides being moving contact pieces without arc-initiating angles. The Venturi nozzle type moving contact piece has a more prominent arc-initiating angle, which allows it to contact the stationary contact system earlier during short-circuit breaking, accelerating the breaking movement time of the moving contact piece. Furthermore, the nozzle type moving contact piece can reduce the arc area and generate a pressure difference, increasing the ionized gas flow rate and causing the arc to be quickly pushed into the upper arc-extinguishing chamber.

[0007] Alternatively, both the intermediate sequence moving contact piece and the two side moving contact pieces are provided with an arc-drawing angle, and the α angle of the intermediate sequence moving contact piece is greater than the α angle of the two side moving contact pieces. The α angle refers to the angle between the line connecting the second rotating shaft 9 and the third rotating shaft 11 and the upper end face of the moving contact piece 3.

[0008] During short-circuit breaking, the arc-initiating angle of the middle sequence moving contact piece will break away from the stationary contact system later than that of the two side moving contact pieces. This structure allows the arc to be concentrated on the middle sequence moving contact piece during short-circuit breaking, and the arc quickly enters the arc-extinguishing chamber along the surface of the arc-initiating piece.

[0009] Furthermore, the α angle of the intermediate sequence moving contact piece is 1 to 2 degrees larger than the α angle of the two side moving contact pieces.

[0010] The upper end of the insulating partition supporting the contact has several slots that match the moving contact pieces. Each moving contact piece is inserted into a slot and contacts the contact spring.

[0011] The contact support is provided with a spring groove. The lower end face of the spring groove is circular, and the upper end face is oval, which can reduce the torsional deformation of the contact spring during the opening and closing process. The contact support has process holes on both sides, and the shaft for adjusting the position of the contact spring is installed in the process holes. There are two rows of spring grooves. During assembly, the contact spring is first placed into the spring groove, and then the shaft for adjusting the position of the contact spring is inserted through the process hole. The shaft is located between the two rows of contact springs, which can restrict the left and right position of the contact spring. Then the moving contact plate is placed in to ensure that the contact spring can smoothly enter the contact spring abutment cavity on the moving contact plate. After assembly, the shaft is pulled out.

[0012] The moving contact piece is provided with a contact spring positioning boss, which is oval, elliptical, or rectangular in shape. Each moving contact piece has two spring positioning bosses, which are located in the two contact spring abutment cavities respectively, corresponding to the two contact springs, and can prevent the contact springs from deviating from their normal positions during the assembly of the moving contact system or during the opening and closing of the circuit.

[0013] The moving contact system also includes a moving busbar, a flexible connection, a side plate, a second rotating shaft, a connecting rod, a third rotating shaft, an arc-blocking cover, and an insulating gasket.

[0014] The moving contact piece and the moving busbar are respectively welded to both ends of the flexible connection. The moving busbar is installed on the second rotating shaft and can rotate around the second rotating shaft. Several moving contact pieces are fixed on both sides by a pair of parallel side plates. One end of each side plate is fixed on the second rotating shaft, and the other end is fixed on the side plates of the contact support. The contact support is covered with an arc-blocking cover. The third rotating shaft is connected to a connecting rod located below the contact support. The connecting rod is connected to the main shaft of the circuit breaker. After the main shaft of the circuit breaker rotates, it can drive the moving contact system to swing, thereby achieving closure or separation from the stationary contact system. The insulating pad is installed between the side plate and the third rotating shaft.

[0015] Furthermore, the arc-blocking cover is provided with an insulating partition to prevent the moving contact piece from being stuck together by metal ions after it breaks, thus affecting the number of parallel branches of the moving contact system.

[0016] The stationary contact system includes a stationary busbar, a stationary contact, an arc-starting plate, and an insulating pad II, with the insulating pad II installed between the arc-starting plate and the stationary busbar.

[0017] The surface of the arc-starting plate is plated with copper, and the width D of the arc-starting plate is 2-3 mm larger than the total width d of the intermediate sequence moving contact plates.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] (1) Fast arc ignition speed and high breaking capacity: The moving contact system adopts the Venturi nozzle type or the larger intermediate sequence α angle type, which has a faster arc ignition speed and higher breaking capacity.

[0020] (2) It has a spring installation and positioning adjustment function: it is equipped with slots and process holes, and the position of the contact spring can be adjusted when the moving contact system is pressed and assembled, making the installation easier and more flexible.

[0021] (3) High stability: The lower end face of the spring groove is set to be circular and the upper end face is set to be oval, which reduces the twisting and deformation of the contact spring during the opening and closing process and enhances the stability of the device;

[0022] (4) High reliability: A contact spring positioning boss is set on the moving contact piece to prevent the contact spring from deviating from the normal position during the assembly of the moving contact system or during the opening and closing of the circuit, thereby improving the reliability of the device. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the contact system of the present invention in the closed state;

[0024] Figure 2 This is a schematic diagram of the moving contact system of the present invention;

[0025] Figure 3 This is a perspective view of the moving contact system of the present invention;

[0026] Figure 4 This is a schematic diagram of the contact support of the present invention;

[0027] Figure 5 This is a schematic diagram of the stationary contact system of the present invention;

[0028] Figure 6 This is a schematic diagram of the moving contact piece of the present invention;

[0029] Figure 7 This is a schematic diagram of the structure of the two moving contact plates;

[0030] Figure 8 This is a schematic diagram of the structure of the intermediate moving contact piece;

[0031] Figure 9 This is a schematic diagram of the arc-blocking cover of the present invention;

[0032] Figure 10 This is a schematic diagram comparing the width of the arc-initiating plate with the total width of the intermediate sequence moving contact plate of the present invention;

[0033] In the diagram: 1-moving busbar, 2-flexible connection, 3-moving contact piece, 301-contact spring positioning boss, 302-flexible connection hole, 303-first shaft hole, 304-contact spring abutment cavity, 305-arc-starting angle, 4-moving contact, 5-contact support, 501-spring groove, 502-process hole, 503-slot, 6-side plate, 7-first rotating shaft, 8-contact spring, 9-second rotating shaft, 10-connecting rod, 11-third rotating shaft, 12-arc-blocking cover, 1201-insulating partition, 1202-shaft hole, 13-insulating gasket one, 14-stationary busbar, 15-stationary contact, 16-arc-starting piece, 17-insulating gasket two, m-middle sequence moving contact piece, n-two moving contact pieces, D-arc-starting piece width, d-total width of middle sequence moving contact pieces. Detailed Implementation

[0034] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The applicant's description of the embodiments is not intended to limit the technical solutions; any formal but not substantive changes made based on the inventive concept should be considered within the scope of protection of the present invention.

[0035] Example 1

[0036] like Figures 1-9 As shown, a contact system of a low-voltage circuit breaker includes a moving contact system and a stationary contact system. The moving contact system includes a moving busbar 1, a flexible connection 2, contact plates 3, contact supports 5, side plates 6, a first rotating shaft 7, a contact spring 8, a second rotating shaft 9, a connecting rod 10, a third rotating shaft 11, an arc-damping cover 12, and an insulating pad 13. Figure 2-3 As shown.

[0037] The contact piece 3 has multiple pieces; in this embodiment, nine pieces are used as an example. The nine moving contact pieces 3 are connected side-by-side to the first rotating shaft 7 through the first shaft hole 303 and can rotate around the first rotating shaft 7. The first rotating shaft 7 is mounted on the contact support 5, and a contact spring 8 is mounted on the contact support 5. The nine moving contact pieces 3 include five intermediate sequence moving contact pieces m and four lateral moving contact pieces n, wherein the intermediate sequence moving contact pieces m are moving contact pieces with an arc-drawing angle 305 (e.g., ...). Figure 6 , 8 The two moving contact pieces n are moving contact pieces with arc-drawing angles; for example... Figure 7 As shown, the α angle (23-25 ​​degrees) of the middle sequence moving contact piece is greater than the α angle (22-23 degrees) of the two side moving contact pieces. The α angle refers to the angle between the line connecting the second rotating shaft 9 and the third rotating shaft 11 and the upper surface of the moving contact piece 3. Figure 7-8 As shown in the comparison between the moving contact piece with an arc-starting angle of 305 and the moving contact pieces on both sides in this embodiment, it can be seen that the arc-starting angle of the ordinary moving contact piece with the moving contact piece having an arc-starting angle of 305 is more prominent, which makes it contact the stationary contact system earlier during short-circuit breaking, accelerates the breaking movement time of the moving contact piece, and utilizes the Venturi effect to set the moving contact piece as a nozzle type, which can reduce the space to generate a pressure difference, increase the free gas flow rate, and make the arc quickly pushed into the upper arc-extinguishing chamber.

[0038] like Figure 6 As shown, the moving contact piece 3 is of the Venturi type. Each moving contact piece 3 has two contact spring abutment cavities 304 on its inner side, and a spring positioning boss 301 with an oval shape is provided in the contact spring abutment cavity 304 to prevent the contact spring 8 from deviating from its normal position during the assembly of the moving contact system or during opening and closing. Each moving contact piece 3 has a moving contact 4 on its outer side, which is connected to or disconnected from the stationary contact 15 of the stationary contact system.

[0039] The moving contact piece 3 is connected to the moving busbar 1 via a flexible connection 2. The moving busbar 1 is mounted on the second rotating shaft 9 and can rotate around the second rotating shaft 9. Several moving contact pieces 3 are fixed on both sides by a pair of parallel side plates 6. One end of each side plate 6 is fixed on the second rotating shaft 9, and the other end is fixed on the side plates of the contact support 5. The contact support 5 is covered with an arc-isolating cover 12. The side plates of the arc-isolating cover 12 are provided with shaft holes 1202. These shaft holes 1202 are screw mounting holes used to fix the arc-isolating cover on the side plate 6. The third rotating shaft 11 is connected to the connecting rod 10 located below the contact support 5. The connecting rod 10 is connected to the circuit breaker main shaft. After the circuit breaker main shaft rotates, it can drive the moving contact system to swing, realizing the closing or separation from the stationary contact system. The insulating pad 13 is installed between the side plate 6 and the third rotating shaft 11.

[0040] like Figure 4 As shown, the upper end of the insulating partition of the contact support 5 has nine slots 503 that match the moving contact pieces 3. Each moving contact piece 3 is inserted into a slot 503 and contacts the contact spring 8. The contact support 5 is also provided with a spring groove 501. The lower end face of the spring groove 501 is circular and the upper end face is oval. Process holes 502 are also provided on both sides of the contact support 5. The process holes 502 contain shafts for adjusting the position of the contact spring 8. There are two rows of spring grooves 501. During assembly, the contact spring 8 is first placed into the spring groove 501. Then, the shaft for adjusting the position of the contact spring 8 is inserted through the process hole 502. The shaft is located between the two rows of contact springs 8 and can restrict the left and right position of the contact spring 8. Then, the moving contact piece 3 is placed in to ensure that the contact spring 8 can smoothly enter the contact spring abutment cavity 304 on the moving contact piece 3.

[0041] like Figure 9 As shown, the arc shield 12 is also provided with an insulating partition 1201, which can prevent the moving contact piece 3 from being stuck by metal ions after it breaks, thus affecting the number of parallel branches of the moving contact system.

[0042] The stationary contact system includes a stationary busbar 14, a stationary contact 15, an arc-starting piece 16, and an insulating pad 17, which is installed between the arc-starting piece 16 and the stationary busbar 14. Figure 1 As shown. The surface of the arc-starting piece 16 is plated with copper, and the width D of the arc-starting piece 16 is 1 mm larger than the total width d of the intermediate sequence moving contact piece m. For example... Figure 10 As shown.

[0043] The installation process in this embodiment is as follows: First, the first rotating shaft 7 is inserted into the first shaft hole 303 of several moving contact pieces 3 to connect the moving contact pieces in parallel. Then, the contact spring 8 is installed in the spring groove 501 of the contact support 5. Next, the spring adjusting shaft is inserted through the process hole 502. Then, the parallel group of moving contact pieces and the first rotating shaft 7 are installed on the contact support 5, so that each moving contact piece 3 is engaged in the slot 503 on the contact support 5 and contacts the contact spring 8. The position of the contact spring 8 is adjusted by the shaft inserted in the process hole 502 to ensure that the contact spring 8 can smoothly enter the contact spring abutment cavity 304 on the moving contact piece 3 for positioning. Finally, the spring adjusting shaft is pulled out. Other parts are installed in place. The total breaking time is shortened by 5ms, and the arcing time is shortened by 3ms.

[0044] Example 2

[0045] In this embodiment, both the intermediate moving contact piece m and the two side moving contact pieces n are provided with an arc-starting angle 305. The α angle of the intermediate moving contact piece m is 1-2 degrees larger than the α angle of the two side moving contact pieces n. During short-circuit breaking, the arc-starting angle 305 of the intermediate moving contact piece m will disconnect from the stationary contact system later than the arc-starting angle 305 of the two side moving contact pieces n. This structure concentrates the arc on the intermediate moving contact piece m during short-circuit breaking. The arc quickly enters the arc-extinguishing chamber along the surface of the arc-starting piece 16. The width D of the arc-starting piece 16 is 2-3 mm larger than the total width d of the intermediate moving contact piece m. The rest of the structure in this embodiment is the same as in embodiment 1.

Claims

1. A contact system for a low-voltage circuit breaker, comprising a moving contact system and a stationary contact system, wherein the moving contact system comprises a plurality of moving contact pieces (3), a moving contact (4), a contact support (5), a first rotating shaft (7), and a contact spring (8), wherein the moving contact (4) is located on the moving contact piece (3), the plurality of moving contact pieces (3) are connected side by side to the first rotating shaft (7) and are rotatable around the first rotating shaft (7), the first rotating shaft (7) is mounted on the contact support (5), and the contact spring (8) is mounted on the contact support (5); characterized in that, The aforementioned moving contact pieces (3) include intermediate sequence moving contact pieces and two side moving contact pieces; The moving contact system also includes a moving busbar (1), a flexible connection (2), a second rotating shaft (9), a connecting rod (10), and a third rotating shaft (11). The moving contact piece (3) is connected to the moving busbar (1) through the flexible connection (2). The moving busbar (1) is mounted on the second rotating shaft (9) and can rotate around the second rotating shaft (9). The third rotating shaft (11) is connected to the connecting rod (10) located below the contact support (5). The intermediate sequence moving contact piece and the two side moving contact pieces are all provided with an arc-drawing angle (305), and the α angle of the intermediate sequence moving contact piece is greater than that of the two side moving contact pieces. The α angle refers to the angle between the line connecting the second rotating shaft (9) and the third rotating shaft (11) and the upper end face of the moving contact piece (3). The shape of the arc-drawing angle on the intermediate sequence moving contact piece is more prominent than that on the two side moving contact pieces, so that the arc-drawing angle on the intermediate sequence moving contact piece contacts the stationary contact system earlier when short-circuit breaking. The α angle of the intermediate sequence moving contact piece is 1 to 2 degrees larger than the α angle of the two side moving contact pieces; the moving contact piece (3) is a Venturi nozzle type; The upper end of the insulating partition of the contact support (5) is provided with a number of slots (503) that match the moving contact piece (3). Each moving contact piece (3) is inserted into the slot (503) and contacts the contact spring (8). The contact support (5) is provided with a spring groove (501), the lower end face of the spring groove (501) is circular and the upper end face is oval. The contact support (5) is provided with process holes (502) on both sides.

2. The contact system of a low-voltage circuit breaker according to claim 1, characterized in that, The moving contact piece (3) is provided with a contact spring positioning boss (301), which is oval, elliptical or rectangular in shape.

3. The contact system of a low-voltage circuit breaker according to claim 1, characterized in that, The moving contact system also includes a side plate (6), an arc shield (12), and an insulating pad (13). Several moving contact pieces (3) are fixed on both sides by a pair of parallel side plates (6). One end of each side plate (6) is fixed on the second rotating shaft (9), and the other end is fixed on the side plates of the contact support (5). The contact support (5) is covered with an arc-blocking cover (12). The side plates of the arc-blocking cover (12) are provided with shaft holes (1202). The insulating pad (13) is installed between the side plate (6) and the third rotating shaft (11).

4. The contact system of a low-voltage circuit breaker according to claim 3, characterized in that, The arc shield (12) is provided with an insulating partition (1201).

5. The contact system of a low-voltage circuit breaker according to claim 1, characterized in that, The stationary contact system includes a stationary busbar (14), a stationary contact (15), an arc-starting plate (16), and an insulating pad II (17), with the insulating pad II (17) installed between the arc-starting plate (16) and the stationary busbar (14); The surface of the arc-starting piece (16) is plated with copper, and the width D of the arc-starting piece (16) is 2-3 mm larger than the total width d of the intermediate sequence moving contact pieces.

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