An arc extinguishing system for a molded case circuit breaker

Abstract

The utility model belongs to the field of circuit breaker, specifically relates to a kind of arc extinguishing system of moulded case circuit breaker, including static contact, moving contact, arc extinguishing chamber and gas production insulating cover, static contact is equipped with U type contact part, the opening of U type contact part is just set to the entrance of arc extinguishing chamber, and its bottom is equipped with a long round hole extending along current direction;Gas production insulating cover and the U type inner wall of U type contact part jointly form an arc chamber with gradually reducing cross section, and the outlet of arc chamber is communicated with the entrance of arc extinguishing chamber;The upper wall of U type contact part is set with static contact point at the place corresponding to the directly above of long round hole, and static contact point is exposed outside gas production insulating cover;When moving contact and static contact separate and produce arc, the magnetic field generated by the current flowing through long round hole area drives arc root displacement and makes it move along the opening direction of U type contact part, the utility model can drive arc by the synergistic effect of magnetic field and airflow, and blow into arc extinguishing chamber quickly and reliably, significantly improve the breaking capacity and electrical life of circuit breaker.

Description

Technical Field

[0001] This utility model belongs to the field of circuit breaker technology, specifically relating to an arc extinguishing system for a molded case circuit breaker. Background Technology

[0002] Molded case circuit breakers (MCCBs) are important circuit protection devices widely used in power distribution systems and electrical equipment to quickly disconnect circuits in the event of short circuits, overloads, or other faults. During the disconnection process, a high-temperature arc is generated between the moving and stationary contacts. How to quickly extinguish this arc, especially limiting and extinguishing the large current arc generated during short circuit faults, is key to improving the breaking capacity of the circuit breaker.

[0003] Existing arc-extinguishing systems typically include a stationary contact, a moving contact, and an arc-extinguishing chamber composed of a set of metal grids. When the contacts separate and an arc is generated, the magnetic field produced by the arc's own current in the circuit conductor causes the arc to move towards the arc-extinguishing chamber, where it is divided, cooled, and extinguished by the grids. However, traditional arc-extinguishing systems have the following shortcomings: First, the magnetic field driving force is limited; for high-current arcs, the arc may stagnate in the contact area, leading to severe contact burn-out. Second, the path of the arc into the arc-extinguishing chamber is not smooth enough, and the speed is slow, prolonging the arc burning time. Finally, if the high-pressure gas generated by the arc combustion is not effectively utilized, it will diffuse disorderly and may even damage other internal components of the circuit breaker.

[0004] Therefore, there is an urgent need for a highly efficient arc extinguishing system that can effectively drive the electric arc, utilize the arc's own energy, and quickly introduce the arc into the arc extinguishing chamber. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings and deficiencies of the existing technology and provide an arc extinguishing system for a molded case circuit breaker. This system can quickly and reliably drive the electric arc and blow it into the arc extinguishing chamber through the synergistic effect of magnetic field and airflow, thereby significantly improving the breaking capacity and electrical life of the circuit breaker.

[0006] To achieve the above objectives, the technical solution adopted by this utility model is as follows: An arc-extinguishing system for a molded case circuit breaker includes a stationary contact, a moving contact, an arc-extinguishing chamber, and a gas-generating insulating cover. One end of the stationary contact is provided with an inlet portion, and the other end with a U-shaped contact portion. The opening of the U-shaped contact portion faces the inlet of the arc-extinguishing chamber, and its bottom has an elongated hole extending along the current direction. The gas-generating insulating cover covers the U-shaped contact portion and, together with the U-shaped inner wall of the U-shaped contact portion, forms an arc-extinguishing cavity with a gradually narrowing cross-section. The outlet of the arc-extinguishing cavity communicates with the inlet of the arc-extinguishing chamber. A stationary contact is provided on the upper wall of the U-shaped contact portion directly above the elongated hole, and this stationary contact is exposed outside the gas-generating insulating cover. When the moving and stationary contacts separate and generate an arc, the magnetic field generated by the current flowing through the elongated hole region drives the root of the arc to displace and move it along the opening direction of the U-shaped contact portion.

[0007] In some embodiments, the tapering structure of the arc-extinguishing chamber can convert the gas expansion pressure generated by the electric arc combustion into a directional airflow. This airflow is aligned with the driving direction of the magnetic field, and together they blow the electric arc into the arc-extinguishing chamber at high speed.

[0008] In some embodiments, the cross-section of the arc-extinguishing cavity gradually decreases from the end near the stationary contact to the end near the arc-extinguishing chamber.

[0009] In some embodiments, the gas-generating insulating cover has two flow-guiding inclined surfaces on both sides of the U-shaped inner wall corresponding to the U-shaped contact portion, and the clamping space between the two flow-guiding inclined surfaces gradually decreases from the end closer to the stationary contact to the end closer to the arc-extinguishing chamber.

[0010] In some embodiments, the tail of the U-shaped contact portion has an arc-starting angle extending toward the arc-extinguishing grid plate in the arc-extinguishing chamber.

[0011] In some embodiments, a step is formed between the arc-drawing angle and the U-shaped contact portion, and the height of the arc-drawing angle is lower than the height of the U-shaped contact portion.

[0012] In some embodiments, the length direction of the elongated hole is parallel to the current flow direction of the stationary contact, and the length of the elongated hole is greater than half the width of the U-shaped bottom of the U-shaped stationary contact.

[0013] In some embodiments, two plug-in pieces are symmetrically arranged on the gas-generating insulating cover, and the two plug-in pieces are respectively inserted into two positioning grooves on the inner wall of the elongated hole.

[0014] In some embodiments, the moving contact tail has an arc-drawing angle extending toward the arc-extinguishing chamber.

[0015] In some embodiments, the moving contact is provided with an arc-shaped convex surface that transitions between the arc-leading angle and the moving contact.

[0016] The beneficial effects of this invention are as follows: By opening an elongated hole at the bottom of the U-shaped contact portion, the current path is altered. When a large current flows through this area, a strong magnetic field perpendicular to the current direction is generated. This magnetic field exerts a powerful Lorentz force on the arc, driving the arc root to move rapidly from the stationary contact area towards the arc-extinguishing chamber. Simultaneously, the gradually narrowing arc-extinguishing chamber, composed of a gas-generating insulating cover and a U-shaped inner wall, effectively converts the high pressure of the arc combustion gas into a directional, high-speed airflow (air blowing effect). This airflow direction is consistent with the magnetic field driving direction, forming a synergistic effect of "magnetic blowing" and "air blowing," greatly accelerating the speed and efficiency of the arc entering the arc-extinguishing chamber. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, obtaining other drawings based on these drawings without creative effort still falls within the scope of this utility model.

[0018] Figure 1 This is a diagram showing the internal structure of the circuit breaker according to an embodiment of the present invention; Figure 2 This is a perspective view of an embodiment of the present utility model; Figure 3 This is a cross-sectional view of an embodiment of the present utility model; Figure 4 This is an assembly diagram of the gas-generating insulating cover and the stationary contact in an embodiment of this utility model. Detailed Implementation

[0019] To make the technical problem to be solved, the technical solution, and the beneficial effects of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this utility model and are not intended to limit this utility model.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0021] The directional and positional terms used in this utility model, such as up, down, front, back, left, right, inside, outside, top, bottom, side, etc., are only for reference to the accompanying drawings. Therefore, the directional and positional terms used are for the purpose of explaining and understanding this utility model, and not for limiting the scope of protection of this utility model.

[0022] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments: like Figure 1-4As shown, an arc-extinguishing system for a molded case circuit breaker includes a stationary contact 1, a moving contact 2, an arc-extinguishing chamber 3, and a gas-generating insulating cover 4. The stationary contact 1 has a wire inlet 11 at one end and a U-shaped contact 12 at the other end. The opening of the U-shaped contact 12 faces the inlet of the arc-extinguishing chamber 3, and its bottom has an elongated hole 13 extending in the current direction. The gas-generating insulating cover 4 covers the U-shaped contact 12 and, together with the U-shaped inner wall of the U-shaped contact 12, forms an arc-extinguishing cavity 400 with a gradually narrowing cross-section. The outlet of the arc-extinguishing cavity 400 communicates with the inlet of the arc-extinguishing chamber 3. A stationary contact 121 is located on the upper wall of the U-shaped contact 12, directly above the elongated hole 13, and is exposed outside the gas-generating insulating cover 4. When the moving and stationary contacts separate and generate an arc, the magnetic field generated by the current flowing through the elongated hole region drives the root of the arc to shift and move it along the opening direction of the U-shaped contact 12. The tapering structure of the arc-extinguishing chamber 400 converts the gas expansion pressure generated by the electric arc combustion into a directional airflow. This airflow, aligned with the driving direction of the magnetic field, propels the electric arc at high speed into the arc-extinguishing chamber 3. The gas generated by the insulating material of the arc-burning chamber experiences increased pressure within the tapering chamber, forming a high-speed airflow. This airflow, aligned with the driving direction of the magnetic field, acts on the arc, producing a powerful arc-blowing effect. This allows the arc to be blown into the arc-extinguishing chamber more quickly and violently, where it is cut, cooled, and extinguished by the grid plates, significantly improving breaking capacity and current-limiting performance. The cross-section of the arc-extinguishing chamber 400 gradually narrows from the end near the stationary contact 121 towards the end near the arc-extinguishing chamber 3. The converging structure of the arc-extinguishing chamber more effectively compresses and accelerates the gas generated by the electric arc combustion, ensuring that the gas expansion pressure is efficiently converted into a high-speed airflow directed towards the arc-extinguishing chamber, enhancing the intensity and directionality of the "air blowing" effect. The gas-generating insulating cover 4 has two guide slopes 41 on both sides of the U-shaped inner wall corresponding to the U-shaped contact portion 12. The clamping space between the two guide slopes 41 gradually decreases from the end closer to the stationary contact 121 to the end closer to the arc-extinguishing chamber 3. Through the design of the guide slope structure, the arc-extinguishing chamber has a gradually narrowing structure. These two slopes act like a "nozzle," which can precisely guide and constrain the airflow direction, making it concentrated and blown at high speed toward the arc-extinguishing chamber inlet. At the same time, it also helps to compress and concentrate the arc, making it easier to be blown into the arc-extinguishing grid.

[0023] like Figure 3 and 4As shown, the tail of the U-shaped contact 12 has an arc-starting angle 122 extending into the arc-extinguishing grid 31 within the arc-extinguishing chamber 3. Setting an arc-starting angle at the tail of the U-shaped contact is equivalent to setting an electromagnetic guiding tip on the path of the arc entering the arc-extinguishing chamber. This tip distorts the surrounding electric field distribution, forming a concentrated area of ​​electric field intensity, and also affects the magnetic field, generating a force that "pulls" or "guides" the arc towards the arc-extinguishing grid, reducing the "threshold" and resistance for the arc to enter the arc-extinguishing chamber, and guiding the arc smoothly into the depths of the arc-extinguishing chamber. A step 123 is formed between the arc-starting angle 122 and the U-shaped contact 12, with the height of the arc-starting angle 122 being lower than the height of the U-shaped contact 123. The step structure formed by the arc-starting angle and the U-shaped contact makes the arc-starting angle even lower. This facilitates the transition area from the stationary contact to the arc-starting angle. When the root of the arc moves to the step under magnetic blow, it is easier to jump from the U-shaped contact to the arc-starting angle, thus entering the arc-extinguishing chamber more smoothly. The length of the elongated hole 13 is parallel to the current flow direction of the stationary contact 1, and the length of the elongated hole 13 is greater than half the width of the U-shaped bottom of the U-shaped stationary contact 1. The parallelism of the length of the elongated hole to the current ensures that the magnetic field generated when the current flows through both sides of the elongated hole is most favorable for driving the arc towards the opening. The length being greater than half the width of the U-shaped bottom ensures that the elongated hole has sufficient size to significantly influence and change the current path, thereby generating a sufficiently strong driving magnetic field. Two symmetrically arranged insert pieces 42 are provided on the gas-generating insulating cover 4, and the two insert pieces 42 are respectively inserted into the two positioning grooves 131 on the inner wall of the elongated hole 13. Through the cooperation of the insert pieces and the positioning grooves, precise positioning and reliable fixation of the gas-generating insulating cover and the U-shaped contact part of the stationary contact are achieved.

[0024] like Figure 1 As shown, the moving contact 2 has an arc-starting angle 21 extending towards the arc-extinguishing chamber 3 at its tail. The arc-starting angle at the tail of the moving contact helps guide the moving contact end of the arc towards the arc-extinguishing chamber, achieving bidirectional guidance and stretching of the entire arc, accelerating the arc's elongation and entry into the arc-extinguishing chamber, and preventing the arc from burning the moving contact. The moving contact 2 has an arc-shaped convex surface 22 that transitions between the arc-starting angle 21 and the moving contact 20. This arc-shaped convex surface on the moving contact provides a smooth transition surface. When the moving contact breaks, the moving contact separates from the stationary contact, and the arc root transfers from the contact surface to this arc-shaped convex surface, eventually sliding towards the arc-starting angle. This prevents the arc from stalling, making the transfer and movement of the arc root smoother and reducing the arc's dwell time in the contact system.

[0025] This invention utilizes an elongated hole at the bottom of the U-shaped contact portion, which alters the current path. When a large current flows through this area, a strong magnetic field perpendicular to the current direction is generated. This magnetic field exerts a powerful Lorentz force on the arc, driving the arc root rapidly from the stationary contact area towards the arc-extinguishing chamber. Simultaneously, the tapering arc-extinguishing chamber, composed of a gas-generating insulating cover and a U-shaped inner wall, effectively converts the high pressure of the arc combustion gas into a directional, high-speed airflow (air blowing effect). This airflow direction aligns with the magnetic field driving direction, creating a synergistic effect of "magnetic blowing" and "air blowing," significantly accelerating the speed and efficiency of the arc entering the arc-extinguishing chamber.

[0026] The above description is only one embodiment of the present utility model and is not intended to limit the scope of protection of the present utility model; the scope of protection of the present utility model is defined by the claims in the claims, and all equivalent changes and modifications made in accordance with the utility model are within the scope of protection of the present utility model patent.

Claims

1. An arc-extinguishing system for a molded case circuit breaker, comprising a stationary contact, a moving contact, an arc-extinguishing chamber, and a gas-generating insulating cover, wherein the stationary contact has a wire inlet at one end and a U-shaped contact at the other end, characterized in that: The opening of the U-shaped contact is positioned directly opposite the inlet of the arc-extinguishing chamber, and its bottom has an elongated hole extending along the current direction; the gas-generating insulating cover covers the U-shaped contact and together with the U-shaped inner wall of the U-shaped contact, forms an arc-extinguishing cavity with a gradually narrowing cross-section, and the outlet of the arc-extinguishing cavity is connected to the inlet of the arc-extinguishing chamber; a stationary contact is provided on the upper wall of the U-shaped contact directly above the elongated hole, and the stationary contact is exposed outside the gas-generating insulating cover; When the moving and stationary contacts separate and generate an electric arc, the magnetic field generated by the current flowing through the elongated hole region drives the root of the arc to shift and move it along the opening direction of the U-shaped contact.

2. The arc extinguishing system for a molded case circuit breaker according to claim 1, characterized in that: The tapering structure of the arc-extinguishing chamber can convert the gas expansion pressure generated by the electric arc combustion into a directional airflow. This airflow is aligned with the driving direction of the magnetic field, and together they blow the electric arc into the arc-extinguishing chamber at high speed.

3. The arc extinguishing system for a molded case circuit breaker according to claim 1 or 2, characterized in that: The cross-section of the arc-extinguishing cavity gradually decreases from the end near the stationary contact to the end near the arc-extinguishing chamber.

4. The arc extinguishing system for a molded case circuit breaker according to claim 3, characterized in that: The gas-generating insulating cover has two flow-guiding inclined surfaces on both sides of the U-shaped inner wall corresponding to the U-shaped contact portion. The clamping space between the two flow-guiding inclined surfaces gradually decreases from the end closer to the stationary contact to the end closer to the arc-extinguishing chamber.

5. The arc extinguishing system for a molded case circuit breaker according to claim 1, characterized in that: The tail of the U-shaped contact portion has an arc-inducing angle that extends into the arc-extinguishing grid plate inside the arc-extinguishing chamber.

6. The arc extinguishing system for a molded case circuit breaker according to claim 5, characterized in that: A step is formed between the arc-drawing angle and the U-shaped contact portion, and the height of the arc-drawing angle is lower than the height of the U-shaped contact portion.

7. The arc extinguishing system for a molded case circuit breaker according to claim 1, characterized in that: The length of the elongated hole is parallel to the current flow direction of the stationary contact, and the length of the elongated hole is greater than half the width of the bottom of the U-shaped stationary contact.

8. The arc extinguishing system for a molded case circuit breaker according to claim 1, characterized in that: The gas-generating insulating cover is symmetrically provided with two plug-in pieces, which are respectively inserted into two positioning grooves on the inner wall of the elongated hole.

9. The arc extinguishing system for a molded case circuit breaker according to claim 1, characterized in that: The moving contact tail has an arc-drawing angle extending toward the arc-extinguishing chamber.

10. The arc extinguishing system for a molded case circuit breaker according to claim 9, characterized in that: The moving contact is provided with an arc-shaped convex surface that transitions between the arc-leading angle and the moving contact.

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