Contact arc extinguishing device for improving circuit breaker breaking capacity

Abstract

The present invention discloses a contact arc extinguishing device for improving the breaking capacity of a circuit breaker. The device comprises two opposing arc-isolating walls, each with two opposing gas-generating plates mounted on its inner wall surface. An arc-extinguishing grid assembly is mounted between the two arc-isolating walls and on the same vertical side of the two gas-generating plates. A stationary contact is positioned below the arc-extinguishing grid assembly. A moving contact is positioned between the two gas-generating plates and rotates vertically at a fixed point, allowing the front end of the moving contact to pass through the arc-extinguishing grid assembly. The front end of the moving contact has an arc-shaped corner protruding from the moving contact point, with the thickness of the corner increasing from the front end toward the moving contact point. The spacing between the two gas-generating plates on the side closest to the arc-extinguishing grid assembly is smaller than on the side farther from the arc-extinguishing grid assembly. This device enhances the arc-strike capability of the moving contact and compresses the arc column diameter, thereby lengthening the arc. It is suitable for improving the breaking capacity of DC and AC circuit breakers.

Description

Technical Field

[0001] The present invention relates to the field of low-voltage electrical technology, in particular to a contact arc extinguishing device that solves the problem of circuit breaker breaking. Background Art

[0002] With the rapid development of DC power supply systems in rail transit, photovoltaic power generation, and other applications requiring DC power, DC appliances with voltages of 1500V or less have become widely used, leading to the emergence of DC circuit breakers. When a circuit breaker interrupts current, an arc is generated. Because DC arcs do not have zero crossings like AC arcs, extinguishing the arc with a DC circuit breaker is more difficult than with an AC circuit breaker.

[0003] GB / T 34581-2017, Section 9.3.9, clearly outlines the requirements for DC critical load current testing. This refers to the operating current at the product's maximum allowable operating voltage, increasing from 4A in increments of two (not exceeding the rated current). Ten interruption tests are conducted at each current, with the maximum average arcing time taken. The maximum arcing time is then used for 100 electrical life tests. During the entire test procedure, prolonged arcing often causes severe contact burnout, preventing smooth test execution. Furthermore, in actual product use, prolonged arcing can shorten product life and even cause fires. The difficulty in extinguishing arcs during interruption at DC critical load current cannot be solved with conventional magnetic blowing methods, primarily because the low current values ​​generate a weak magnetic blowing force, making it difficult to blow the arc into the arc quenching grid. Currently, there are few complete solutions for addressing arc extinguishing during critical load current interruption in DC circuit breakers. Summary of the Invention

[0004] Purpose of the invention: In view of the above problems, the purpose of the present invention is to provide a contact arc extinguishing device on a circuit breaker, especially to solve the problem that it is difficult to extinguish the arc when the DC circuit breaker is disconnected.

[0005] Technical solution: A contact arc extinguishing device for improving the breaking capacity of a circuit breaker, comprising an arc isolation wall, a gas production plate, a moving contact, a static contact, and an arc extinguishing grid group; two oppositely arranged arc isolation walls are provided with two oppositely arranged gas production plates on their inner wall surfaces; the arc extinguishing grid group is installed between the two arc isolation walls and is located on the same vertical side of the two gas production plates; the static contact is arranged below the arc extinguishing grid group; the moving contact is arranged between the two gas production plates and is rotated vertically at a fixed point so that the front end of the moving contact passes through the arc extinguishing grid group; the front end of the moving contact has a circular arc angle protruding from the moving contact point, and the thickness of the arc angle increases from the front end of the moving contact to the moving contact point, and the spacing between the two gas production plates on the side close to the arc extinguishing grid group is smaller than the spacing on the side away from the arc extinguishing grid group.

[0006] The arc angle is conducive to the movement of the arc along the arc-shaped surface of the arc angle, and the arc angle of the arc surface can reduce the resistance of the arc transferring from the moving contact through the arc angle to the arc extinguishing grid group.

[0007] The thickness structure of the arc angle can maintain the arc. After the arc is smoothly transferred to the arc angle area, it can effectively stretch the arc length, increase the arc column voltage, and enhance the arc extinguishing effect.

[0008] The structure of the gas production plate has a smaller spacing. On the one hand, it can compress the arc column diameter, increase the arc pressure, and facilitate arc extinguishing. On the other hand, the gas production plate can have more complete contact with the arc and produce more neutral free gas.

[0009] Optimally, the distance between the gas production plate and the opposing surface of the moving contact is 2 to 3 mm.

[0010] Furthermore, when the moving contact rotates upward to open the switch, the moving contact's repulsion limit position is no higher than the gas production plate.

[0011] Furthermore, the material of the gas production plate is melamine, polyformaldehyde, or nylon.

[0012] Furthermore, a stopper is provided above the moving contact to set an upper limit on the upward rotation of the opening switch.

[0013] Furthermore, the arc striking pin on the static contact is located below and parallel to the lowest grid of the arc extinguishing grid group.

[0014] Beneficial effect: Compared with the prior art, the advantage of the present invention is that the contact arc extinguishing device can be improved and implemented while maintaining the original size of the circuit breaker. By enhancing the arc striking ability of the moving contact and compressing the arc column diameter, the arc is elongated, thereby improving the breaking capacity of the critical load current of the DC circuit breaker. At the same time, it is also suitable for improving the breaking capacity of DC circuit breakers and AC circuit breakers. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention;

[0016] Figure 2 for Figure 1 Schematic diagram of the internal structure with one arc-isolating wall and one gas-producing plate removed on the same side;

[0017] Figure 3 This is the main view of the moving contact;

[0018] Figure 4 for Figure 3 A top view of

[0019] Figure 5 for Figure 1 A-direction end view;

[0020] Figure 6 Schematic diagram of the arc when the moving contact rotates upward to open the circuit breaker. DETAILED DESCRIPTION

[0021] The present invention will be further described below with reference to the accompanying drawings and specific examples. These examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0022] A contact arc extinguishing device for improving the breaking capacity of a circuit breaker, as shown in the attached Figure 1 、 2 As shown in , 5 and 6, it includes an arc-isolating wall 1, a gas-producing plate 2, a moving contact 3, a static contact 4 and an arc-extinguishing grid group 5.

[0023] Two arc-isolating walls 1 are vertically opposed to each other with a gap between them. Their lower ends can be mounted on the base of the DC circuit breaker, while their upper ends can contact the upper cover of the DC circuit breaker. The arc-isolating walls are secured by the base and upper cover of the DC circuit breaker. A gas-generating plate 2 is riveted to the opposing inner walls of each arc-isolating wall 1. The two gas-generating plates 2 are vertically opposed to each other with a gap between them. The gas-generating plates 2 are made of melamine, polyoxymethylene, nylon, or other gas-generating materials. The arc-extinguishing grid assembly 5 is located between the two arc-isolating walls 1, on the same vertical side of the two gas-generating plates 2, and is riveted to the arc-isolating walls 1.

[0024] The static contact 4 is positioned below the arc-quenching grid assembly 5 and is fixed to the base of the DC circuit breaker. The arc-strike pin 42 on the static contact 4 is positioned below and parallel to the lowest grid of the arc-quenching grid assembly 5. The moving contact 3 is positioned between two gas-generating plates 2. The rear end of the moving contact 3 is connected to a rotating shaft 7, which rotates vertically around the rotating shaft 7. The rotating shaft 7 is fixed to the DC circuit breaker. As the moving contact 3 rotates, its front end passes through the arc-quenching grid assembly 5. When the moving contact 3 rotates downward to close the circuit, the moving contact 31 below the front end of the moving contact 3 contacts the static contact 41 on the static contact 4. When the moving contact 3 rotates upward to open the circuit, the front end of the moving contact 3 is positioned between the two gas-generating plates 2, and the moving contact 31's repelling limit position does not exceed the gas-generating plates 2. Corresponding to this position, a stopper 6 fixed to the DC circuit breaker is positioned above the moving contact 3 to limit the upward rotation of the moving contact 3 to open the circuit. The opening and closing of the moving contact 3 can be controlled by changing the action mechanism from a four-link to a five-link.

[0025] Combined with attachment Figure 3 、 4 As shown, the front end of the movable contact 3 has an arc-shaped corner 32 protruding from the movable contact point 31. The corner 32 is chamfered from its side wall in the thickness direction, forming a thickness increasing from the front end of the automatic contact 3 to the movable contact point 31.

[0026] Combined with attachment Figure 5As shown, the moving contact 3 is between the two gas producing plates 2, and the distance a between the two gas producing plates 2 on the side close to the arc extinguishing grid group 5 is smaller than the distance b on the side away from the arc extinguishing grid group 5, that is, the distance between the two gas producing plates 2 shrinks from the side away from the arc extinguishing grid group 5 to the side close to the arc extinguishing grid group 5, and there is a distance of 2 to 3 mm between the opposite surfaces of the gas producing plates 2 and the moving contact 3.

[0027] When the DC circuit breaker is energized and manually disconnected, the moving contact and the static contact change from the closed state to the open state, and an arc is formed between the moving contact and the static contact. Since the current value in the system circuit is small at this time, the magnetic blowing force of the arc cannot effectively blow the arc into the arc extinguishing grid group. Therefore, the arc continues to burn between the moving contact and the static contact, and the arc exists between the moving contact and the static contact.

[0028] To this end, during the opening process, the arc moves and transfers as the moving contact rotates. The gas-producing plate generates high temperature under the action of the arc, which promotes the production of neutral free gas. Since the distance a between the two gas-producing plates on the side close to the arc extinguishing grid group is relatively small, on the one hand, the arc column diameter of the arc can be compressed, the arc voltage can be increased, and it is beneficial to arc extinguishing. On the other hand, the gas-producing plate can be in more complete contact with the arc and can produce more neutral free gas. The free gas cools the arc temperature and blows the arc into the arc extinguishing grid group. Driven by the free gas, the arc moves along the arc-shaped surface of the arc angle at the front end of the moving contact. The arc angle of the circular surface can reduce the resistance of the arc to transfer from the moving contact through the arc angle to the arc extinguishing grid group. In addition, the thickness of the arc angle automatically decreases from the contact to the front end of the moving contact, which can maintain the arc. After the arc is smoothly transferred to the arc angle area, the arc length can be effectively stretched, the arc column voltage can be increased, and the arc extinguishing effect can be enhanced.

[0029] The contact arc extinguishing device can be improved and implemented while maintaining the original size of the DC circuit breaker. By enhancing the arc striking ability of the moving contact and compressing the arc column diameter, the arc is elongated, thereby improving the breaking capacity of the DC circuit breaker for the critical load current. At the same time, it is also suitable for improving the breaking capacity of DC circuit breakers and AC circuit breakers.

Claims

1. A contact arc extinguishing device for improving the breaking capacity of a circuit breaker, comprising an arc-isolating wall (1), a gas-producing plate (2), a moving contact (3), a static contact (4), and an arc-extinguishing grid group (5); two oppositely arranged arc-isolating walls (1) are provided with two oppositely arranged gas-producing plates (2) on their inner wall surfaces; the arc-extinguishing grid group (5) is installed between the two arc-isolating walls (1) and is located on the same vertical side of the two gas-producing plates (2); the static contact (4) is provided below the arc-extinguishing grid group (5); the moving contact (3) is provided between the two gas-producing plates (2) and is rotated vertically at a fixed point so that the front end of the moving contact (3) passes through the arc-extinguishing grid group (5); the characteristics are: The front end of the moving contact (3) has an arc-shaped arc angle (32) protruding from the moving contact (31), and the thickness of the arc angle (32) increases from the front end of the moving contact (3) to the moving contact (31). The spacing between the two gas-producing plates (2) on the side close to the arc-extinguishing grid group (5) is smaller than the spacing on the side away from the arc-extinguishing grid group (5); when the moving contact (3) rotates upward to open the switch, the repulsion limit position of the moving contact (31) is not higher than the gas-producing plate (2); a stopper (6) for upper limit rotation of the opening switch is provided above the moving contact (3); the arc-strike foot (42) on the static contact (4) is located below the lowest grid of the arc-extinguishing grid group (5) and is parallel to it; the spacing between the opposite surfaces of the gas-producing plate (2) and the moving contact (3) is 2 to 3 mm; the material of the gas-producing plate (2) is melamine, polyformaldehyde, or nylon.

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