A two-pole DC high voltage molded case circuit breaker with arc extinguishing device

Abstract

The present invention provides a two-pole DC high-voltage molded case circuit breaker with an arc extinguishing device, which relates to the field of circuit breakers. The circuit breaker includes a circuit breaker body and a top cover shell. The arc extinguishing device is arranged in the circuit breaker body, the arc extinguishing device is arranged in the top cover shell, an arc extinguishing grid assembly is arranged in the arc extinguishing device, an arc extinguishing grid assembly is arranged in the arc extinguishing device, and a cavity is arranged between the arc extinguishing device and the arc extinguishing device; the arc extinguishing grid assembly includes a first arc extinguishing grid assembly, a second arc extinguishing grid assembly and a third arc extinguishing grid assembly, the first arc extinguishing grid assembly is located above the second arc extinguishing grid assembly, and the third arc extinguishing grid assembly is arranged below the first arc extinguishing grid assembly and behind the second arc extinguishing grid assembly. The circuit breaker of the present invention is reliable in breaking and avoids violent arcing, greatly improves the arc extinguishing and arc extinguishing effects of the circuit breaker, and can avoid the wiring post from being eroded and damaged by the arc, thereby improving the safety of the circuit.

Description

Technical Field

[0001] The invention relates to the technical field of circuit breakers, and in particular to a two-pole DC high-voltage molded case circuit breaker with an arc extinguishing device. Background Art

[0002] In modern power systems, from large motor drives in industrial production to various electrical equipment in residential buildings, the distribution and control of electricity are everywhere. As a key component to ensure the safe and stable operation of the circuit, the molded case circuit breaker is responsible for cutting off the circuit in the event of overload, short circuit and other faults, preventing damage to electrical equipment and serious accidents such as fire. With the development of the power system, the performance requirements for molded case circuit breakers are also increasing. When the circuit breaker cuts off the circuit, an arc will be generated at the moment of contact separation. If the arc cannot be extinguished quickly, it will cause many serious problems. On the one hand, the high temperature generated by the arc can reach thousands of degrees Celsius or even higher, which will cause the contact material to melt, gasify and ablate quickly, greatly shorten the service life of the contact, increase the maintenance cost and replacement frequency of the equipment; on the other hand, the long-term existence of the arc will cause the surrounding insulation materials to be subjected to thermal radiation and ion bombardment, resulting in a decrease in insulation performance, which may cause phase-to-phase short circuit or ground fault, endangering the safe and stable operation of the entire power system, and even in some extreme cases, it may cause a fire, causing significant casualties and property losses.

[0003] At present, molded case circuit breakers have also taken some measures in arc extinguishing, such as arc extinguishing devices and arc extinguishing devices are set in molded case circuit breakers. The arc is divided into multiple short arcs by the arc extinguishing grids set in the arc extinguishing device. When the arc voltage rises and exceeds the power supply voltage, the arc cannot be maintained and extinguishes. After the arc extinguishing device extinguishes the arc, there are often some residual free electrons and ions, and these residual free particles are removed by the arc extinguishing device.

[0004] However, in the prior art, molded case circuit breakers with both arc extinguishing devices and arc extinguishing devices have arc extinguishing devices that are too close to each other, which may cause the following problems: First, the narrow space will increase the difficulty of installation, and in subsequent maintenance and inspection, it is difficult to separately inspect and replace the arc extinguishing device and the various components of the arc extinguishing device; Second, the arc extinguishing device will generate a large amount of heat during the arc extinguishing process. If the distance between the two is too close, the heat is difficult to dissipate quickly in the narrow space, and the arc extinguishing device may be affected by the heat of the arc extinguishing device, resulting in a decrease in the performance of the adsorption material in the arc extinguishing device. In addition, the existing circuit breakers have problems such as unreliable breaking, low breaking index, poor performance, and violent arcing due to the unreasonable setting of the arc extinguishing device and arc extinguishing device. The above problems will eventually lead to poor arc extinguishing effect of the circuit breaker. Therefore, in order to meet the requirements of modern power systems for high performance and high reliability of molded case circuit breakers, it is of great practical significance and urgency to develop an efficient arc extinguishing device for molded case circuit breakers. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art and to provide a two-pole DC high-voltage molded case circuit breaker with an arc extinguishing device.

[0006] The technical solution adopted by the present invention is as follows: a two-pole DC high-voltage molded case circuit breaker with a free arc extinguishing device, comprising a circuit breaker body and a top cover shell, wherein the top cover shell is connected to one end of the circuit breaker body, a moving contact, a static contact and an arc extinguishing device are arranged in the circuit breaker body, an arc extinguishing device is arranged in the top cover shell, an arc extinguishing grid assembly is arranged in the arc extinguishing device, an arc extinguishing grid assembly is arranged in the arc extinguishing device, a cavity is arranged between the arc extinguishing device and the arc extinguishing device, and the moving contact has an opening position separated from the static contact and a closing position electrically connected to the static contact by rotating up and down;

[0007] The arc-extinguishing grid assembly includes a first arc-extinguishing grid assembly, a second arc-extinguishing grid assembly and a third arc-extinguishing grid assembly, wherein the first arc-extinguishing grid assembly is located above the second arc-extinguishing grid assembly, and the third arc-extinguishing grid assembly is arranged below the first arc-extinguishing grid assembly and behind the second arc-extinguishing grid assembly, wherein the first arc-extinguishing grid assembly is composed of a plurality of mutually parallel first arc-extinguishing grids, and a plurality of the first arc-extinguishing grids are arranged downwardly inclined toward the opening position, wherein the second arc-extinguishing grid assembly is composed of a plurality of mutually parallel second arc-extinguishing grids, and a plurality of the second arc-extinguishing grids are arranged upwardly inclined toward the closing position, and wherein the third arc-extinguishing grid assembly is composed of a plurality of mutually parallel third arc-extinguishing grids, and the third arc-extinguishing grids are arranged parallel to the first arc-extinguishing grids.

[0008] The two-pole DC high-voltage molded case circuit breaker with a free arc extinguishing device also includes a first arc-striking plate. When the moving contact is in the opening position, the moving contact is electrically connected to the first arc-striking plate. A plurality of the first arc-extinguishing grids are each provided with a first arc-striking groove at one end close to the moving contact, and a plurality of the second arc-extinguishing grids are each provided with a second arc-striking groove. A plurality of the first arc-striking grooves and a plurality of the second arc-striking grooves form an arc-striking slideway, and the moving contact is opened and closed in the arc-striking slideway. The first arc-extinguishing grid in the middle part of the first arc-extinguishing grid assembly is arranged closer to the moving contact than the first arc-extinguishing grids on both sides, so that the first arc-extinguishing grid in the middle part forms an arc-striking tip.

[0009] A second arc-striking plate is also provided in the arc-extinguishing device, and the second arc-striking plate includes a front end portion, a middle portion and a rear end portion, the front end portion is located between the first arc-extinguishing grid assembly and the second arc-extinguishing grid assembly, and the end away from the middle portion is bent toward the second arc-extinguishing grid assembly to form a bending portion, the distance between the front end portion and the first arc-extinguishing grid assembly gradually increases as it moves away from the moving contact, the middle portion is inclined toward the second arc-extinguishing grid assembly, and the rear end portion is arranged between the first arc-extinguishing grid assembly and the third arc-extinguishing grid assembly.

[0010] An arc isolation plate is also provided in the arc extinguishing device on the side of the arc extinguishing grid assembly away from the cavity. The arc isolation plate includes a first arc isolation plate, a second arc isolation plate and a third arc isolation plate which are arranged in sequence along the direction away from the arc extinguishing device. The first arc isolation plate, the second arc isolation plate and the third arc isolation plate are respectively provided with a plurality of first through holes, a plurality of second through holes and a plurality of third through holes. The diameter of the third through hole is larger than that of the first through hole and larger than that of the second through hole.

[0011] A fourth through hole is arranged on the side wall of the top cover shell close to the arc isolation plate corresponding to the arc isolation plate, and the cross-sectional area of ​​the fourth through hole is larger than the cross-sectional areas of the first through hole, the second through hole and the third through hole.

[0012] A mounting groove is arranged in the top cover shell, the arc extinguishing device is arranged in the mounting groove, and the lower end of the mounting groove away from the arc extinguishing device is communicated with the outside.

[0013] The arc extinguishing device also includes a top cover, an arc isolation wall and a gas producing block. Two arc isolation walls are symmetrically arranged. The two arc isolation walls and the top cover form a accommodating cavity. The arc extinguishing grid assembly is composed of a plurality of fourth arc extinguishing grids parallel to each other and arranged in the accommodating cavity. The plurality of fourth arc extinguishing grids are arranged in a horizontal direction and are provided with fourth arc striking grooves. The gas producing blocks are symmetrically arranged in the accommodating cavity and are located on both sides of the fourth arc striking groove, and are used to generate gas that can extinguish the arc.

[0014] A third arc-striking plate is also provided at the lower end of the arc-extinguishing device, and the static contact extends downward to form an extension plate. The extension plate passes through the second arc-striking groove, and the lower end extends out of the second arc-extinguishing grid assembly and is opposite to the third arc-striking plate. The end of the third arc-striking plate away from the extension plate is located between the third arc-extinguishing grid assembly and the cavity.

[0015] The two-pole DC high-voltage molded case circuit breaker with a free arc extinguishing device also includes a partition plate for separating the arc extinguishing device from the arc extinguishing device, the partition plate includes an upper partition plate and a lower partition plate, the upper partition plate is arranged corresponding to the arc extinguishing device and has a plurality of fifth through holes arranged thereon, and the lower partition plate can shield the lower part of the cavity and the arc extinguishing device.

[0016] The two-pole DC high-voltage molded case circuit breaker with a free arc extinguishing device also includes a guide column, which is arranged at the upper part of the cavity. The guide column and the cavity form an annular airway, and the annular airway is communicated with the arc extinguishing device. A terminal is arranged below the guide column in the cavity, and an insulating plate is arranged at the lower end of the guide column corresponding to the lower part of the partition plate. The insulating plate and the guide column are used to separate the terminal and the arc extinguishing device.

[0017] The beneficial effects of the present invention are as follows:

[0018] 1. The present invention is provided with an arc extinguishing device and an arc extinguishing device, so that the circuit breaker can be disconnected reliably, has good performance, and avoids violent arcing. A cavity is provided between the two, which improves the arc extinguishing effect of the circuit breaker;

[0019] 2. The arc extinguishing device of the present invention is provided with three sets of arc extinguishing grid components corresponding to the moving contact movement tracks and with different inclination angles, which greatly improves the arc extinguishing effect;

[0020] 3. The present invention provides an insulating plate to prevent the terminal from being damaged by arc erosion, thereby improving the safety of the circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, without paying creative labor, other drawings obtained based on these drawings still belong to the scope of the present invention.

[0022] Figure 1 For the purpose of illustrating the present invention Figure 1 ;

[0023] Figure 2 The arc extinguishing device of the present invention is shown in FIG. Figure 1 ;

[0024] Figure 3 The arc extinguishing device of the present invention is shown in FIG. Figure 2 ;

[0025] Figure 4 It is a schematic diagram of the arc extinguishing device of the present invention;

[0026] Figure 5 For the purpose of illustrating the present invention Figure 2 ;

[0027] Figure 6 It is a schematic diagram of the top cover shell of the present invention;

[0028] Figure 7 for Figure 1 A magnified view of middle;

[0029] Figure 8 Schematic diagram of the partition plate of the present invention. DETAILED DESCRIPTION

[0030] In order to make the technical means, creative features, objectives and effects of the present invention easy to understand, the present invention is further described below in conjunction with specific embodiments, but the following embodiments are only preferred embodiments of the present invention, not all. Based on the embodiments in the implementation mode, other embodiments obtained by those skilled in the art without creative work are all within the scope of protection of the present invention.

[0031] It should be noted that all expressions using "first" and "second" in the embodiments of the present invention are for distinguishing two non-identical entities with the same name or non-identical parameters. It can be seen that "first" and "second" are only for the convenience of expression and should not be understood as limitations on the embodiments of the present invention. The subsequent embodiments will not explain this one by one.

[0032] The directions and positions mentioned in the present invention, such as "upper", "lower", "front", "back", "left", "right", "inside", "outside", "top", "bottom", "side", etc., are only for reference to the directions or positions of the drawings. Therefore, the directions and positions used are for explaining and understanding the present invention, but not for limiting the scope of protection of the present invention.

[0033] like Figures 1 to 8 As shown, an embodiment of the present invention is provided:

[0034] A two-pole DC high-voltage molded case circuit breaker with an arc extinguishing device comprises a circuit breaker body 1, a top cover shell 2, a moving contact 7, and a stationary contact 8. The moving contact 7 can rotate up and down to have an opening position separated from the stationary contact 8 and a closing position electrically connected to the stationary contact 8.

[0035] The top cover shell 2 is connected to one end of the circuit breaker body 1, and the top cover shell 2 mainly serves to fix the arc extinguishing device and exhaust. The circuit breaker body 1 is provided with an arc extinguishing device, the circuit breaker body 1 is provided with a moving contact 7, a static contact 8 and an arc extinguishing device, the top cover shell 2 is provided with an arc extinguishing device, the arc extinguishing device is provided with an arc extinguishing grid assembly 3, and the arc extinguishing device is provided with an arc extinguishing grid assembly 4. If the arc extinguishing grid assembly 3 and the arc extinguishing grid assembly 4 are too close, the following problems may occur: first, the narrow space will increase the difficulty of installation, and it is difficult to separately inspect and replace the arc extinguishing device and the various components of the arc extinguishing device in subsequent maintenance inspections; second, the arc extinguishing device will generate a large amount of heat during the arc extinguishing process. If the distance between the two is too close, the heat is difficult to dissipate quickly in the narrow space, and the arc extinguishing device may be affected by the heat of the arc extinguishing device, resulting in a decrease in the performance of the adsorption material in the arc extinguishing device. In order to avoid the above-mentioned problems, a cavity 5 is provided between the arc extinguishing device and the arc extinguishing device, and an arc isolation plate 6 is also provided on the side of the arc extinguishing grid assembly 4 in the arc extinguishing device away from the cavity 5. The arc isolation plate 6 mainly plays the role of quickly extinguishing the arc, reducing the arcing distance, achieving zero arcing and preventing particulate matter from entering the arc extinguishing chamber.

[0036] The arc-extinguishing grid assembly 3 includes a first arc-extinguishing grid assembly 31, a second arc-extinguishing grid assembly 32 and a third arc-extinguishing grid assembly 33. The first arc-extinguishing grid assembly 31 is located above the second arc-extinguishing grid assembly 32, and the third arc-extinguishing grid assembly 33 is arranged below the first arc-extinguishing grid assembly 31 and behind the second arc-extinguishing grid assembly 32. The first arc-extinguishing grid assembly 31 is composed of a plurality of mutually parallel first arc-extinguishing grids, and a plurality of the first arc-extinguishing grids are arranged downwardly inclined toward the opening position. The second arc-extinguishing grid assembly 32 is composed of a plurality of mutually parallel second arc-extinguishing grids, and a plurality of the second arc-extinguishing grids are arranged upwardly inclined toward the closing position. The third arc-extinguishing grid assembly 33 is composed of a plurality of mutually parallel third arc-extinguishing grids, and the third arc-extinguishing grids are arranged parallel to the first arc-extinguishing grids. The first arc-extinguishing grid is arranged at an angle of α relative to the horizontal position, the second arc-extinguishing grid is arranged at an angle of β relative to the horizontal position, and the third arc-extinguishing grid is arranged at an angle of γ relative to the horizontal position, wherein α is 5-15°, β is 150-170°, and γ is 5-15°. Specifically, in the present embodiment, α, β, and γ are set to 8°, 170°, and 8°.

[0037] The circuit breaker further includes a first arc-striking plate 9. When the moving contact 7 is in the opening position, the moving contact 7 is electrically connected to the first arc-striking plate 9. A first arc-striking groove 311 is provided at one end of a plurality of the first arc-extinguishing grids close to the moving contact 7. A second arc-striking groove 321 is provided on a plurality of the second arc-extinguishing grids. A plurality of the first arc-striking grooves 311 and a plurality of the second arc-striking grooves 321 form an arc-striking slideway, and the moving contact 7 is opened and closed in the arc-striking slideway. Moreover, the first arc-striking grid in the middle part of the first arc-striking grid assembly 31 is arranged closer to the moving contact 7 than the first arc-striking grids on both sides, so that the first arc-striking grid in the middle part forms an arc-striking tip.

[0038] A second arc-striking plate 10 is also provided in the arc-extinguishing device. The second arc-striking plate 10 includes a front end portion 101, a middle portion 102 and a rear end portion 103. The front end portion 101 is located between the first arc-extinguishing grid assembly 31 and the second arc-extinguishing grid assembly 32, and is used to lead out the arc at the middle position of the moving track of the moving contact 7; and one end away from the middle portion 102 is bent toward the second arc-extinguishing grid assembly 32 to form a bending portion 104, which can change the direction of the arc and make part of it be diverted to the second arc-extinguishing grid, thereby improving the arc extinguishing efficiency and effect; the distance between the front end portion 101 and the first arc-extinguishing grid assembly 31 gradually increases as it moves away from the moving contact 7, which can lengthen the arc between the first arc-extinguishing grid and the front end portion 101, which is beneficial to cooling the arc and further improving the arc extinguishing effect; the middle portion 102 is inclined toward the second arc-extinguishing grid assembly 32, and the rear end portion 103 is arranged between the first arc-extinguishing grid assembly 31 and the third arc-extinguishing grid assembly 33.

[0039] In order to extinguish the arc at the end of the static contact 8 and move the residual arc after arc extinguishing toward the arc extinguishing device, a third arc-striking plate 13 is also provided at the lower end of the arc extinguishing device. The static contact 8 extends downward to form an extension plate 81. The extension plate 81 passes through the second arc-striking groove 321, and the lower end extends out of the second arc-striking grid assembly 32 and is opposite to the third arc-striking plate 13. The end of the third arc-striking plate 13 away from the extension plate 81 is located between the third arc-striking grid assembly 33 and the cavity 5.

[0040] By setting the above arc extinguishing device, the circuit breaker can divide and extinguish the arc and start the arc within the moving track of the moving contact 7 by using the first arc extinguishing grid assembly 31, the second arc extinguishing grid assembly 32, the second arc striking plate 10 and the third arc striking plate 13. In addition, the second arc extinguishing grid is tilted upward toward the closing position, which is conducive to transferring the remaining arc after division to the third arc extinguishing grid, while the first arc extinguishing grid is tilted downward toward the opening position, and the third arc extinguishing grid is arranged in parallel with the first arc extinguishing grid, which is conducive to leading the arc toward the arc extinguishing device and reducing the movement of the arc toward the terminal.

[0041] The arc isolation plate 6 includes a first arc isolation plate 61, a second arc isolation plate 62 and a third arc isolation plate 63 which are sequentially arranged in a direction away from the arc extinguishing device. The first arc isolation plate 61, the second arc isolation plate 62 and the third arc isolation plate 63 are respectively provided with a plurality of first through holes, a plurality of second through holes and a plurality of third through holes, and the diameter of the third through holes is larger than the first through holes and larger than the second through holes. A fourth through hole 21 is provided on the side wall of the top cover shell 2 close to the arc isolation plate 6 corresponding to the arc isolation plate 6, and the cross-sectional area of ​​the fourth through hole 21 is larger than the cross-sectional area of ​​the first through hole, the second through hole and the third through hole. The first through hole, the second through hole, the third through hole and the fourth through hole 21 are used for exhaust.

[0042] In order to improve the arc extinguishing effect, the arc extinguishing device further includes a top cover 42, an arc isolation wall 43 and a gas production block 44. Two arc isolation walls 43 are symmetrically arranged. The top cover 42 mainly serves to isolate the arc and fix the arc isolation wall 43, while the arc isolation wall 43 mainly isolates the arc so as to quickly extinguish the arc. The gas production block 44 mainly produces arc extinguishing gas under high temperature and high pressure so as to blow the arc into the arc extinguishing grid assembly 4. The two arc isolation walls 43 and the top cover 42 form a receiving cavity. The arc extinguishing grid assembly 4 is composed of a plurality of fourth arc extinguishing grids 41 parallel to each other and arranged in the receiving cavity. The plurality of fourth arc extinguishing grids 41 are arranged in a horizontal direction and are provided with fourth arc striking grooves 411. The gas production blocks 44 are symmetrically arranged in the receiving cavity and located on both sides of the fourth arc striking groove 411, and are used to produce gas that can extinguish the arc. Furthermore, the thickness of the gas production block 44 gradually increases along the direction approaching the fourth arc-extinguishing grid assembly 4 , which is conducive to the free arc particles entering the arc-extinguishing grid assembly 4 along the gas production block 44 .

[0043] In addition, a mounting groove 22 is provided in the top cover 2, and the arc extinguishing device is provided in the mounting groove 22. The lower end of the mounting groove 22 away from the arc extinguishing device is communicated with the outside. Specifically, the arc extinguishing grid assembly can be assembled and then installed in the mounting groove 22, and the top cover 2 is connected to the circuit breaker body, which is convenient for installation and disassembly, and also provides convenience for later maintenance or replacement of parts.

[0044] The circuit breaker is also provided with a partition plate 14 for separating the arc extinguishing device from the arc extinguishing device, the partition plate 14 includes a partition plate upper portion 141 and a partition plate lower portion 142, the partition plate upper portion 141 is provided corresponding to the arc extinguishing device and is provided with a plurality of fifth through holes 1411, and the partition plate lower portion 142 can shield the lower portion of the cavity 5 and the arc extinguishing device. Further, a guide column 11 is also provided, the guide column 11 is provided at the upper portion of the cavity 5, the guide column 11 and the cavity 5 form an annular airway, the annular airway is communicated with the arc extinguishing device, a terminal 12 is provided below the guide column 11 in the cavity 5, an insulating plate 111 is provided at the lower end of the guide column 11 corresponding to the partition plate lower portion 142, the insulating plate 111 and the guide column 11 are used to separate the terminal 12 and the arc extinguishing device, through the above-mentioned arrangement, the arc can be prevented from eroding the terminal 12, thereby improving the safety of the circuit.

[0045] The above disclosure is only the preferred embodiment of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. A two-pole DC high voltage molded case circuit breaker with a free arc extinguishing device, characterized in that: The invention comprises a circuit breaker body (1) and a top cover shell (2), wherein the top cover shell (2) is connected to one end of the circuit breaker body (1), wherein a moving contact (7), a stationary contact (8) and an arc extinguishing device are arranged in the circuit breaker body (1), wherein the top cover shell (2) is arranged in the arc extinguishing device, wherein an arc extinguishing grid assembly (3) is arranged in the arc extinguishing device, wherein an arc extinguishing grid assembly (4) is arranged in the arc extinguishing device, wherein a cavity (5) is arranged between the arc extinguishing device and the arc extinguishing device, wherein the moving contact (7) has an opening position separated from the stationary contact (8) and a closing position electrically connected to the stationary contact (8) by rotating up and down; The arc-extinguishing grid assembly (3) comprises a first arc-extinguishing grid assembly (31), a second arc-extinguishing grid assembly (32) and a third arc-extinguishing grid assembly (33); the first arc-extinguishing grid assembly (31) is located above the second arc-extinguishing grid assembly (32); the third arc-extinguishing grid assembly (33) is arranged below the first arc-extinguishing grid assembly (31) and behind the second arc-extinguishing grid assembly (32); the first arc-extinguishing grid assembly (31) is composed of a plurality of mutually parallel first arc-extinguishing grids, wherein the plurality of first arc-extinguishing grids are arranged downwardly and tilted toward an opening position; the second arc-extinguishing grid assembly (32) is composed of a plurality of mutually parallel second arc-extinguishing grids, wherein the plurality of second arc-extinguishing grids are arranged upwardly and tilted toward a closing position; the third arc-extinguishing grid assembly (33) is composed of a plurality of mutually parallel third arc-extinguishing grids, wherein the third arc-extinguishing grids are arranged in parallel with the first arc-extinguishing grids.

2. A two-pole DC high voltage molded case circuit breaker with a stray arc extinguishing device according to claim 1, characterized in that: The invention also comprises a first arc-striking plate (9); when the moving contact (7) is in the opening position, the moving contact (7) and the first arc-striking plate (9) are electrically connected; a first arc-striking groove (311) is provided at one end of a plurality of the first arc-extinguishing grids close to the moving contact (7); a second arc-striking groove (321) is provided on a plurality of the second arc-extinguishing grids; a plurality of the first arc-striking grooves (311) and a plurality of the second arc-striking grooves (321) form an arc-striking slideway; and the moving contact (7) is opened and closed in the arc-striking slideway.

3. A two-pole DC high voltage molded case circuit breaker with a stray arc extinguishing device according to claim 2, characterized in that: A second arc-striking plate (10) is also provided in the arc-extinguishing device. The second arc-striking plate (10) comprises a front end portion (101), a middle portion (102) and a rear end portion (103). The front end portion (101) is located between the first arc-extinguishing grid assembly (31) and the second arc-extinguishing grid assembly (32), and one end away from the middle portion (102) is bent toward the second arc-extinguishing grid assembly (32) to form a bent portion (104). The distance between the front end portion (101) and the first arc-extinguishing grid assembly (31) gradually increases away from the moving contact (7). The middle portion (102) is inclined toward the second arc-extinguishing grid assembly (32), and the rear end portion (103) is provided between the first arc-extinguishing grid assembly (31) and the third arc-extinguishing grid assembly (33).

4. A two-pole DC high voltage molded case circuit breaker with a stray arc extinguishing device according to claim 1, characterized in that: An arc isolation plate (6) is further provided in the arc extinguishing device at a side of the arc extinguishing grid assembly (4) away from the cavity (5), the arc isolation plate (6) comprising a first arc isolation plate (61), a second arc isolation plate (62) and a third arc isolation plate (63) which are sequentially arranged in a direction away from the arc extinguishing device, the first arc isolation plate (61), the second arc isolation plate (62) and the third arc isolation plate (63) are respectively provided with a plurality of first through holes, a plurality of second through holes and a plurality of third through holes, the diameter of the third through holes being greater than the diameter of the first through holes and greater than the diameter of the second through holes.

5. A two-pole DC high voltage molded case circuit breaker with a stray arc extinguishing device according to claim 4, characterized in that: A fourth through hole (21) is provided on a side wall of the top cover shell (2) close to the arc isolation plate (6) corresponding to the arc isolation plate (6), and the cross-sectional area of ​​the fourth through hole (21) is greater than the cross-sectional areas of the first through hole, the second through hole, and the third through hole.

6. A two-pole DC high voltage molded case circuit breaker with a stray arc extinguishing device according to claim 1, characterized in that: A mounting groove (22) is provided in the top cover shell (2), the arc extinguishing device is arranged in the mounting groove (22), and the mounting groove (22) is communicated with the outside at a lower end away from the arc extinguishing device.

7. A two-pole DC high voltage molded case circuit breaker with a stray arc extinguishing device according to claim 1, characterized in that: The arc extinguishing device further comprises a top cover (42), an arc isolation wall (43) and a gas generating block (44); two arc isolation walls (43) are symmetrically arranged; the two arc isolation walls (43) and the top cover (42) form a receiving cavity; the arc extinguishing grid assembly (4) is composed of a plurality of mutually parallel fourth arc extinguishing grids (41) and is arranged in the receiving cavity; the plurality of fourth arc extinguishing grids (41) are arranged in a horizontal direction and are provided with fourth arc striking grooves (411); the gas generating blocks (44) are symmetrically arranged in the receiving cavity and are located on both sides of the fourth arc striking groove (411) and are used to generate gas capable of extinguishing an arc.

8. A two-pole DC high voltage molded case circuit breaker with a stray arc extinguishing device according to claim 2, characterized in that: A third arc-striking plate (13) is further provided at the lower end of the arc-striking device; the stationary contact (8) extends downward to form an extension plate (81); the extension plate (81) passes through the second arc-striking groove (321) and the lower end of the extension plate extends out of the second arc-striking grid assembly (32) to face the third arc-striking plate (13); an end of the third arc-striking plate (13) away from the extension plate (81) is located between the third arc-striking grid assembly (33) and the cavity (5).

9. A two-pole DC high voltage molded case circuit breaker with a stray arc extinguishing device according to claim 1, characterized in that: It also includes a partition plate (14) for separating the arc extinguishing device from the arc extinguishing device, the partition plate (14) comprising a partition plate upper portion (141) and a partition plate lower portion (142), the partition plate upper portion (141) being arranged corresponding to the arc extinguishing device and having a plurality of fifth through holes (1411) arranged thereon, and the partition plate lower portion (142) being capable of shielding the lower portion of the cavity (5) and the arc extinguishing device.

10. A two-pole DC high voltage molded case circuit breaker with a stray arc extinguishing device according to claim 1, characterized in that: It also comprises a guide column (11), the guide column (11) being arranged at the upper part of the cavity (5), the guide column (11) and the cavity (5) forming an annular air passage, the annular air passage being in communication with the arc extinguishing device, a terminal post (12) being arranged below the guide column (11) in the cavity (5), an insulating plate (111) being arranged at the lower end of the guide column (11) corresponding to the lower part (142) of the partition plate, the insulating plate (111) and the guide column (11) being used to separate the terminal post (12) and the arc extinguishing device.

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