CN100593833C - Contact system of a molded case circuit breaker - Google Patents

Abstract

A contact system of a low-voltage switchgear, such as a circuit breaker, which uses the principle of the combination of electromagnetic repulsion and gas pressure, a structure in which the dynamic and static contacts can swing and repel at the same time, and an automatic magnetic blowout arc system. It can speed up the breaking speed between the dynamic and static contacts, increase the separation distance between the dynamic and static contacts, and accelerate the extinguishing of the arc, thereby improving its performance index of rapid current limiting and arc extinguishing. The contact system of the invention has compact structure, small volume and low production cost.

Description

Contact system of a molded case circuit breaker

technical field

The invention relates to a contact system of a low-voltage switch, in particular to a contact system of a molded case circuit breaker with fast current limiting and arc extinguishing performance.

Background technique

The contact system is an essential and important part of low-voltage switchgear. Its current limiting performance and arc extinguishing performance are important performance indicators of switchgear, especially in circuit breakers. The requirements for this indicator are more prominent, and to improve this The key is to speed up the breaking speed of the dynamic and static contacts, increase the opening distance of the dynamic and static contacts, and improve the arc extinguishing efficiency of the arc extinguishing system.

The common current-limiting contact system is the static contact repulsive type. When the short-circuit current passes, the opening of the moving contact can be accelerated under the action of electromagnetic repulsion, and the opening distance increases at the same time, the arc is elongated, and the arc voltage is reduced. Boost to improve current limiting performance. In this system, the static contact is fixed on a bracket through a shaft, and the bracket is fixed on the base by screws, and the connecting plate and the static contact are connected through a soft connection. The height of the bracket plays a decisive role in the deflection stroke of the static contact. , so in order to obtain a better current limiting effect, the height of the bracket is higher, so that the shape of the product is also higher, and the production cost is increased.

Japan's Mitsubishi Corporation's Impulse Narrow Aisle Accelerated (ISTAC) breaking technology discloses a three-force combined contact system, which can accelerate the opening of the moving contact, lead out the arc earlier, increase the arc voltage, and improve the current limiting performance. The existing three-force combined contact system has the following structural forms.

Such as the patent of invention whose application number is 99805439.9, the principle of the contact system of this prior art circuit breaker is to utilize the following three forces to accelerate the breaking speed of the moving contact: the direction of the current on the connecting plate of the static contact and the direction of the current on the moving contact The electromagnetic attraction to the moving contact produced by the same current direction; the electromagnetic repulsion to the moving contact produced by the opposite direction of the current on the static contact and the current on the moving contact; the polymer material produces high quality when breaking the short-circuit current. Arc extinguishing gas, the gas pressure on the moving contact produced by the expansion of the gas and the surrounding air in a narrow space. Since the moving contact must be opened/closed with the static contact in a swinging manner, a through slot is opened in the contact connecting plate of the contact system, so that the moving contact can extend into the fixed contact connecting plate through the slot. At the static contact, the opening/closing between the dynamic and static contacts is realized. For this reason, the current on the connecting plate of the static contact is divided into two paths due to slotting, each path of current is on the oblique top of the moving contact, and they are not on the extension surface of the swing track of the moving contact, that is, each path of current is for There is a relatively large angle between the direction of the electromagnetic attraction force of the moving contact and the extension surface of the swinging track of the moving contact. Due to the existence of this angle, the electromagnetic attraction force on the moving contact generated by the current on the connecting plate of the static contact is actually the component force of the electromagnetic attraction force of each current on the moving contact, and the component force is equal to the The product of the electromagnetic attraction force and the cosine of the included angle causes the electromagnetic attraction force between them to be very small.

It can be seen from the structural principle of the above-mentioned three-force combined contact system that the contact system in the prior art has the following three main defects.

First of all, the electromagnetic force formed by the current divided into two paths on the connecting plate and the current on the moving contact is very small, and there is a large gap between the direction of the electromagnetic force and the extension surface of the swinging track of the moving contact. Therefore, the current on the connection plate has very little electromagnetic attraction to the moving contact, and its effect is not obvious. However, in order to obtain this force, it is necessary to increase and lengthen the connection plate. Since the enlarged and lengthened connecting plate occupies a large space in the arc extinguishing chamber, the number of arc extinguishing grids has to be reduced, which significantly weakens the arc extinguishing ability of the contact system, prolongs the burning time of the arc, and enhances the arc extinguishing capacity. The energy of the arc and the gas pressure in the product shell make the arc easily fly out of the product shell, which greatly reduces the safety and reliability of the product. In practical applications, this contact system does not significantly improve the current limiting performance. On the contrary, because the contact system is designed in such a shape, the space for accommodating the arc extinguishing chamber is reduced, so the volume of the arc extinguishing chamber and the arc extinguishing chamber have to be reduced. The number of grid pieces makes the arc burn for a long time and it is difficult to extinguish it in a very short time. On the other hand, if the volume of the arc extinguishing chamber is not reduced, the external dimensions of the product must be increased, making the product bulky and increasing the material cost.

Secondly, the positions of the two currents on the connecting plate are located obliquely below or obliquely above the movable contact. There is a large included angle between them, and this included angle will bring a vertical component force that interferes with its swing to the moving contact, and the vertical component force is equal to the product of the electromagnetic force and the sine of the included angle. Since the directions of the vertical component forces generated by the two currents are opposite, when the two currents are equal in intensity and distributed symmetrically with the swinging track plane of the moving contact, the two vertical component forces can be offset. When the current intensities of the two paths are not equal or distributed asymmetrically with the swing track surface of the moving contact, the two vertical components cannot be offset, and the resultant force between them will slow down the breaking speed of the moving contact. In actual production and manufacturing, in order to reduce the influence of the vertical component force on the breaking speed of the moving contact, the processing accuracy of the parts and the assembly accuracy of the parts have to be improved, so that the manufacturing difficulty and production cost of the product have to be increased.

The third is to reduce the impact damage to product parts caused by long arc burning time, large arc energy and high gas pressure in the product shell. The existing contact system has complex structure, large volume and high production cost. high.

Contents of the invention

The purpose of the present invention is to provide a contact system with rapid breaking, current limiting and arc extinguishing performance that overcomes the above-mentioned defects of the prior art. The structure that the head can swing and repel at the same time, and the automatic magnetic blowout arc extinguishing system, the space occupied by the contact system is very small, which ensures that the arc extinguishing chamber has a large enough volume, and can speed up the breaking speed between the dynamic and static contacts. The distance between the moving and static contacts is widened to accelerate the extinguishing of the arc, thereby improving the performance index of rapid current limiting and arc extinguishing, and the cost is also significantly reduced.

In order to achieve the above purpose, the contact system of the present invention adopts the following technical solutions.

The circuit breaker contact system of the present invention is composed of a static contact part, a moving contact part, an arc extinguishing chamber and an arc extinguishing grid installed in the arc extinguishing chamber. The moving contact part includes a moving contact arm and a moving contact, The arc extinguishing chamber is composed of the shell and the shell cover through rivet riveting, and there is a connecting plate connected with the main circuit on the static contact part. The static contact part includes a bracket, which is connected with the connecting plate and fixed with the arc extinguishing chamber; a static contact with a static contact arm is pivotally installed on the bracket; a spring is used for static The contact provides closing contact force and drives the static contact to reset; a limit mechanism is used for swing limit and static positioning of the static contact. The static contact arm is arranged below the movable contact arm, so that the direction of the current (i1) flowing through the static contact arm is opposite to that of the current (i1) flowing through the movable contact arm, so as to automatically generate the dynamic and static contacts electromagnetic repulsion between them. Above the static contact arm and between the static contact arm and the movable contact arm, there are reflective plates and insulation plates made of polymer gas-generating materials, and the reflective plates are installed on the static contact arms It is used to generate gas pressure to push the moving and static contacts apart when breaking the short-circuit current, and use it to protect the parts in the static contact parts from being burned by the arc. The bracket is made of U-shaped structure with excellent magnetic-conducting material, which is used to form a magnetic blowing system. When the moving and static contacts are in the process of breaking, when an arc occurs, the arc current (i2) will make the U-shaped The magnetic blowing system of the structure generates a magnetic field, and the direction of the magnetic force line (H) is perpendicular to the direction of the arc current i2, and the direction of the force (F) of the magnetic force line (H) on the arc current is not only perpendicular to the direction of the magnetic force line (H), but also Perpendicular to the direction of the arc current (i2) and also towards the direction of the arc chute, this magnetic field is used to blow the arc into the arc chute, thereby extinguishing it quickly. When a short circuit occurs in the circuit and the current (i1) flowing through the dynamic and static contacts of the contact system exceeds the rated value, relying on the electromagnetic repulsion (F1) generated by the current (i1) flowing through the dynamic and static contacts, The moving contact and the static contact are oscillated and repelled at the same time, and the gas pressure generated by the reflector and the insulating plate is used to accelerate the speed of the swaying and repelling of the moving contact and the static contact at the same time, thereby realizing rapid breaking and current limiting.

The bracket is an integral part formed by two side plates (10g), two flanges (10a) and a bottom plate (10f) in a U-shaped structure. Two holes (10e) are symmetrically arranged at one end of the two side plates (10g) for installing the pivot shaft on the static contact arm, which is used to pivot the static contact with the static contact arm Mounted on a stand. In the middle of the two side plates (10g), there is symmetrically a limit groove (10d), which is used to install the limit shaft arranged on the static contact arm. The limit groove (10d) and the limit The shaft constitutes the limiting mechanism, which is used to realize the limiting of the static contact when it swings and the positioning when it is static. The opening of the U-shaped structure faces the direction in which the movable contact repels and swings, and the contact points of the movable and static contacts are between the U-shaped structure and the arc chute to form the magnetic lines of force that push the arc into the arc chute (H). At least one protrusion is arranged on the outer surfaces of the two side plates (10g), through which the support and the arc extinguishing chamber are fixed and positioned.

The spring can be a torsion spring, compression spring or leaf spring, which is installed on the bracket or the arc extinguishing chamber through a mounting structure, one end of which is connected to the static contact, and the other end is connected to the bracket or the arc extinguishing chamber. The elastic force of the spring acting on the static contact provides ideal working contact force to the dynamic and static contacts, and drives the static contact to reset when it is static.

The two flanges of the bracket can be straight or angled.

Insulating plates are arranged on the inner sides of the two flanges (10a) of the bracket of the U-shaped structure respectively, so as to prevent the two flanges of the bracket 10 from being burnt by the arc, and the insulating plates can also function under the high temperature of the arc. It plays the role of decomposing high-quality gas that is beneficial to cooling the arc.

At least one connection hole (10c) is arranged on the base plate (10f), through the connection hole (10c), the base plate (10f) is mechanically connected to the connection plate, and the base plate (10f) and the connection plate can also be directly welded on Together.

The connecting plate is connected to the static contact arm through a conductor, so that they have a more ideal electrical connection performance.

The hole (10e) is the center of rotation of the static contact, and is protrudingly arranged on the outer surfaces of the two side plates (10g).

The described installation structure for installing the spring can be a spring shaft for installing the spring and at least one hole (10b) for fixing the spring shaft, and the at least one hole (10b) for fixing the spring shaft (8) ) is set on the bracket or the arc extinguishing chamber. The installation structure for installing the spring may also be a groove provided on the bracket or the arc extinguishing chamber, and the groove provided on the bracket or the arc extinguishing chamber is used to clamp the spring.

It can be seen from the descriptions of the above technical solutions that the contact system of the present invention has the following main advantages:

1. The direction of the current flowing between the moving and static contacts is opposite to automatically generate electromagnetic repulsion;

2. A reflective plate and an insulating plate made of polymer gas-generating materials are provided between the contact arms of the dynamic and static contacts to automatically generate gas pressure when the dynamic and static contacts are broken;

3. Adopt the principle of the combination of electromagnetic repulsion and gas pressure to speed up the repulsion speed of the dynamic and static contacts, so the current limiting effect is remarkable;

4. Adopting the structure that the dynamic and static contacts can swing and repel at the same time, it can not only speed up the repulsion speed of the dynamic and static contacts, but also increase the distance between the dynamic and static contacts to destroy the stability of the arc combustion;

5. The magnetic blowing system composed of U-shaped brackets is adopted, and the magnetic field generated by the arc current is used to push the arc into the arc extinguishing grid, so the larger the breaking current, the more significant the arc extinguishing effect;

6. The contact system of the present invention is compact in structure and small in size, so that the precious space in the arc extinguishing chamber is used to increase the number of arc extinguishing grids, so the arc extinguishing effect is particularly good.

The contact system of the invention is mainly used in plastic case circuit breakers, and can also be used in other low-voltage switchgears.

Description of drawings

Fig. 1 is a structural schematic diagram of an embodiment of the circuit breaker contact system of the present invention, illustrating the breaking working principle of the contact system.

Fig. 2 is a schematic structural view of the arc extinguishing chamber part of the embodiment of the circuit breaker contact system of the present invention.

Fig. 3a and Fig. 3b are structural schematic diagrams of the static contact part of the embodiment of the contact system of the present invention.

Fig. 4 is a schematic diagram of the U-shaped structure of the bracket of the embodiment of the contact system of the present invention.

Fig. 5 is a schematic diagram of the arc extinguishing working principle of the circuit breaker contact system embodiment of the present invention.

Detailed ways

Specific embodiments of the circuit breaker contact system with rapid current limiting and arc extinguishing performance of the present invention will be described in detail below with reference to the accompanying drawings, and the circuit breaker contact system of the present invention is not limited to the following embodiments.

As shown in FIGS. 1 and 2 , the contact system of the present invention includes a static contact part 100 , a moving contact part 200 , an arc extinguishing grid 3 and an arc extinguishing chamber 300 .

As shown in Figure 1, the moving contact part 200 is pivotally connected to the base of the circuit breaker through a shaft system structure (not shown in the figure). When the operating mechanism of the circuit breaker drives the moving contact part 200 for closing operation, the moving The movable contact 201 of the contact part 200 contacts and closes the static contact 101 of the static contact part 100, so that the current i1 is connected. When the circuit breaker is tripped to trip, or the operating mechanism of the circuit breaker drives the moving contact part 200 for opening operation, the moving contact 201 of the moving contact part 200 is separated from the static contact 101 of the static contact part 100, Disconnect the current i1 (as shown in Figure 1).

When the movable contact 201 is in contact with the static contact 101, the movable contact arm 202 is arranged parallel to the static contact arm 102, and the distance between them is very small (not shown in the figure), the current flowing through the movable contact arm 202 The direction of the current flowing through the static contact arm 102 is opposite, so when the current i1 flowing through the movable and static contacts exceeds the rated value due to a fault such as a short circuit in the main circuit, there will be a sufficiently large electromagnetic repulsion between the movable and static contacts The force F1, under the action of the electromagnetic repulsion force F1, the movable contact 201 and the static contact 101 will automatically and rapidly open to cut off the current i1.

As shown in FIG. 2 , the arc extinguishing chamber 300 includes a housing 1 , a housing cover 5 and a rivet 2 . A sealed arc extinguishing chamber is formed by the shell 1, the shell cover 5 and the rivet 2 to prevent the electric arc from leaking out. The static contact part 100 and the arc extinguishing grid 3 are arranged in the arc extinguishing chamber 300 as shown in FIG. 2 . The moving contact 201 (not shown in the figure) of the moving contact part 200 can protrude into the arc extinguishing chamber 300 to contact and close with the static contact 101 . The arc extinguishing grid 3 is arranged close to the static contact 101 to obtain an ideal arc extinguishing effect.

As shown in FIG. 3a and FIG. 3b , the static contact part 100 is composed of a static contact 101 , a bracket 10 , a connecting plate 9 , a conductor 15 , a pivot shaft 12 , a limit shaft 11 , a spring shaft 8 and a spring 7 .

The static contact 101 is pivotally connected to the bracket 10 through the static contact arm 102 and the pivot shaft 12 , so that the static contact 101 can flexibly swing around the pivot shaft 12 . Two limit shafts 11 are arranged on both sides of the static contact arm 102, two limit grooves 10d are arranged on both sides of the bracket 10, and the limit mechanism is formed by the cooperation of the limit shaft 11 and the limit groove 10d. The swing angle of the static contact 101 around the pivot shaft 12 is defined. The spring 7 is installed on the spring shaft 8, and the spring shaft 8 is fixedly connected with the bracket 10. One end of the spring 7 is connected to the static contact arm 102, and the other end is connected to the bottom plate 10f of the bracket 10. The spring force direction of the spring 7 is toward the moving contact, so as to drive the static contact toward the moving contact 201 (not shown in the figure) direction swing, and provide ideal contact force for dynamic and static contacts. When the static contact 101 has no external force other than the elastic force, it resets under the elastic force of the spring 7 and is in the position shown in Fig. 3a and Fig. 3b. If the static contact 101 is subjected to the electromagnetic repulsion force F1 (shown in FIG. 1 ), and F1 is greater than the elastic force, the static contact 101 will swing downwards, and the maximum angle of its swing is limited by the limit slot 10d to avoid swinging If the angle is too large, the static contact 101 will collide with other components. The bracket 10 is mechanically connected to the connecting plate 9 through the connecting hole 10C thereon. The mechanical connection may be riveted or screwed, or the bottom plate 10f and the connecting plate 9 may be directly welded together. The connecting plate 9 is connected to the static contact arm 102 through the conductor 15, so that they have good electrical connection performance. The connecting plate 9 is electrically connected with the incoming or outgoing wires of the main circuit through the wiring hole 91 or the wiring socket (not shown in the figure) thereon. Above the static contact arm 102 and between the movable contact arm 202, there is a reflector 13 made of a polymer gas-generating material. The air between the movable contact arms 202 rapidly expands in the narrow space, thereby generating gas pressure to push the movable contact arms 202 to disconnect, so as to increase the disconnection speed of the movable contacts; to protect the pivot shaft 12 and the limit shaft 11 from being Arc burnout. The inboards of the two flanges 10a of the bracket 10 are respectively provided with insulating plates 14, which are used to prevent the two flanges of the bracket 10a from being burned by the arc, and simultaneously the insulating plates can be decomposed under the high temperature of the arc, which is beneficial to High quality gas for cooling the arc.

From Fig. 3a, Fig. 3b and Fig. 4, it is not difficult to get the following inspiration: the spring 7 can be a torsion spring (as shown in Fig. 3a, Fig. 3b), but it can also be a leaf spring or a compression spring; The shaft 8 is installed on the bracket 10, but it can also be fixed on the arc extinguishing chamber 300 through the space below the bracket 10, especially when a leaf spring or compression spring is used, this structure is more suitable.

As shown in Fig. 4, the support 10 is an integral element of a U-shaped structure composed of two side plates 10g, two flanges (10a) and a bottom plate 10f, that is, they are an inseparable unity. At both ends of the two side plates 10g, two holes 10e and two holes 10b are symmetrically provided. The hole 10e is used to install the pivot shaft 12 on the static contact 101 (shown in Fig. 3a, Fig. 3b). The hole 10b is used for mounting the spring shaft 8 (shown in Figs. 3a, 3b). The structural strength of the bracket 10 can also be strengthened through the assembly and connection of the side plate 10g and the pivot shaft 12 and the spring shaft 8 . In the middle of the two side plates 10g, two limiting grooves 10d are symmetrically provided for installing the limiting shaft 11 (shown in Fig. 3a and Fig. 3b) arranged on the static contact arm (102), which The function is to limit the static position and swing angle of the static contact. At least one connecting hole 10C is provided on the bottom plate 10f, which is used to realize a close mechanical connection between the bottom plate 10f and the connecting plate 9 (shown in FIGS. 3a and 3b). The mechanical connection can be riveted or screwed, or The bottom plate 10f and the connecting plate 9 are directly welded together. Two flanges 10a are arranged symmetrically at appropriate positions of the two side plates 10g, and a U-shaped magnetic blowing system for arc blowing is formed by the flanges 10a and the bottom plate 10f. The opening of the U-shaped structure faces the direction in which the moving contact (201) repels and swings, so that the direction of the magnetic force line at the opening of the U-shaped structure is perpendicular to the direction of the arc current between the moving and static contacts. The contact points of the moving and static contacts are between the U-shaped structure and the arc extinguishing grid 3 , so that the magnetic field lines of the U-shaped structure blow the arc into the arc extinguishing grid 3 . The bracket 10 is made of excellent magnetically permeable material to enhance the intensity of the arc blowing magnetic field, thereby increasing the strength of the magnetic blowing. Outward protrusions are provided around the holes 10e on the outer surfaces of the two side plates 10g for fixing and positioning the bracket 10 with the housing 1 and the case cover 5 (shown in FIG. 2 ).

The working principle of quick breaking, current limiting and arc extinguishing of the contact system of the present invention will be further described below in conjunction with FIG. 1 and FIG. 5 .

Since the direction of the current i1 flowing through them in the closed state of the moving contact 201 and the static contact 101 is opposite, when the main circuit is short-circuited and the current i1 exceeds the rated value, the electromagnetic repulsion force F1 generated by the current i1 of the main circuit, It can drive the moving contact 201 and the static contact 101 to move away quickly at the same time, that is, the moving contact 201 quickly swings away from the static contact 101, and the static contact 101 quickly swings away from the moving contact 201. Because the dynamic and static contacts are repelled at the same time, the speed of repelling is accelerated. Since the static contact arm 102 is lighter than the movable contact arm 202, its repelling action is more sensitive and the opening speed is faster. Since the reflector 13 and the insulating plate 14 can quickly generate gas when breaking, and form a gas pressure that pushes the moving contact arm 201 and the static contact arm 101 to repel, the pressure further increases the repulsion between the moving and static contacts , Further speeding up the speed of repulsion between them.

Due to the combination of electromagnetic repulsion force and gas pressure, and the simultaneous swing of the static contact 101 and the moving contact 201, the moving and static contacts can be quickly repelled, which can quickly increase the arc resistance and increase the arc. Therefore, the circuit breaker contact system of the present invention not only has the advantages of fast breaking speed and good current limiting effect, but also has the remarkable advantage of fast arc extinguishing, and its main advantages are reflected in the following four points:

The first is the working principle of the above-mentioned combination of two forces and the simultaneous swinging and repelling of the dynamic and static contacts. It can not only draw out the current earlier, increase the arc voltage, realize rapid breaking and rapid current limiting, but also increase the dynamic and static contacts. The opening distance between the heads quickly elongates and thins the arc, destroys the stable combustion of the arc, and makes it extinguish quickly.

Secondly, the contact system of the present invention has a small and efficient magnetic blowing arc extinguishing system, that is, the magnetic blowing system composed of the U-shaped structure of the bracket 10 as shown in FIG. 5 . Since the support 10 is made of excellent magnetically conductive material, it can be known according to the principle of electromagnetism that when the arc current i2 flows in the direction shown in Figure 5, the magnetic blowing system can generate a magnetic field, and the direction of its magnetic force line H is consistent with the arc current The direction of i2 is vertical, and the direction of the force F exerted by the magnetic force line H on the arc current i2 is not only perpendicular to the direction of the magnetic force line H, but also perpendicular to the direction of the arc current i2, and at the same time, it also faces the arc extinguishing grid 3, thereby pushing the arc into the arc extinguishing grid 3 were quickly divided, cooled and extinguished. It can be seen from the above principles that the greater the breaking current of the contact system of the present invention is, the more significant the effect of magnetic blowout arc extinguishing is.

The third is that the contact system of the present invention is very compact, which solves a series of technical problems such as the support, flipping and swinging, swinging limit, and elastic reset of the static contact part 100 in a limited space, greatly reducing its The space occupied by the arc extinguishing chamber 300 is used to increase the number of arc extinguishing grids, thereby further enhancing the performance of arc extinguishing.

The fourth is that the contact system of the present invention is arranged in the sealed arc extinguishing chamber 300 composed of the shell 1 and the shell cover 5 made of high-strength material. Because of its good current limiting and arc extinguishing performance, the arc is difficult to Flying out from the arc extinguishing chamber can even achieve the effect of zero flashover, thereby greatly improving the safety level of electrical products, and at the same time reducing the material requirements and manufacturing costs of the base and shell of electrical products manufactured using this contact system.

Claims (10)

1. A contact system of a circuit breaker, which consists of a static contact part (100), a moving contact part (200), an arc extinguishing chamber (300) and an arc extinguishing grid (3) installed in the arc extinguishing chamber, The moving contact part includes a moving contact arm (202) and a moving contact (201), and the arc extinguishing chamber (300) is riveted by the casing (1) and the casing cover (5) via a rivet (2). Composition, a connecting plate (9) connected to the main circuit is provided on the static contact part (100), and it is characterized in that: The static contact part (100) includes a bracket (10), which is connected to the connecting plate (9) and fixed with the arc extinguishing chamber (300); a static contact arm (102) The contact (101) is pivotally installed on the bracket (10); a spring (7) is used to provide a closing contact force to the static contact and drive the static contact (101) to reset; a limit mechanism is used to Perform swing limit and static positioning on the static contact (101); The static contact arm (102) is arranged below the movable contact arm (202), so that the current (i1) flowing through the static contact arm (102) and the current (i1) flowing through the movable contact arm (202) ) in the opposite direction to automatically generate electromagnetic repulsion between the dynamic and static contacts; Above the static contact arm (102) and between the static contact arm and the movable contact arm (202), there is a reflective plate (13) made of polymer gas-generating material; The bracket (10) is made of a U-shaped structure made of excellent magnetically permeable material, which is used to form a magnetic blowing system. When an arc occurs during the breaking process of the moving and static contacts, the arc current (i2) will make the The U-shaped structure of the magnetic blowing system generates a magnetic field, and the direction of its magnetic force line (H) is perpendicular to the direction of the arc current (i2), and the direction of the force (F) of the magnetic force line (H) on the arc current is not only in line with the direction of the magnetic force line (H) vertical, and also perpendicular to the direction of the arc current (i2), and also towards the direction of the arc chute (3), this magnetic field is used to blow the arc into the arc chute, thereby extinguishing it quickly; When a short circuit occurs in the circuit and the current (i1) flowing through the moving and static contacts exceeds the rated value, the moving contacts ( 201) and the static contact (101) swing and repel at the same time, the reflector (13) produces high-quality arc extinguishing gas, and the gas expands with the surrounding air to generate gas pressure on the moving contact in a narrow space, so as to realize rapid breaking and Limiting. 2. The contact system according to claim 1, characterized in that: The bracket (10) is an integral part formed by two side plates (10g), two flanges (10a) and a bottom plate (10f) in a U-shaped structure; The two flanges (10a) are provided with insulating plates (14); Two holes (10e) are symmetrically arranged at one end of the two side plates (10g), and are used to install the pivot shaft (12) on the static contact arm (102), which is used to connect the static contact arm ( 102) the static contact (101) is pivotally mounted on the bracket (10); In the middle of the two side plates (10g), two limiting slots (10d) are symmetrically provided for installing the limiting shaft (11) arranged on the static contact arm (102). (10d) and the limit shaft (11) form the limit mechanism, which is used to realize the limit of the static contact (101) when swinging and the positioning when it is static; The opening of the U-shaped structure faces the moving contact (201) in the direction of repelling and swinging, and the contact point of the moving and static contacts is between the U-shaped structure and the arc extinguishing grid (3), so as to push the arc forward to extinguish the arc. The magnetic field lines (H) of the grid (3); At least one protrusion is arranged on the outer surfaces of the two side plates (10g), through which the bracket (10) and the arc extinguishing chamber (300) are fixed and positioned. 3. The contact system according to claim 1, characterized in that: the spring (7) is a torsion spring, compression spring or leaf spring, which is installed on the bracket (10) or the arc extinguishing chamber through a mounting structure (300), one end of which is connected to the static contact (101), and the other end is connected to the support (10) or the interrupter (300), and the spring (7) acts on the elastic force of the static contact (101), Provide ideal working contact force to the dynamic and static contacts, and drive the static contacts (101) to reset when static. 4. The contact system according to claim 2, characterized in that: the insulating plates (14) are respectively arranged on the inner side of the two flanges (10a) of the U-shaped bracket (10), In order to prevent the two flanges of the support (10) from being burned by the arc, at the same time, the insulating plate can also decompose high-quality gas that is beneficial to cooling the arc under the high temperature of the arc. 5. The contact system according to claim 2, characterized in that: at least one connection hole (10c) is provided on the bottom plate (10f), and the bottom plate (10f) is connected to the connection plate (10f) through the connection hole (10c). 9) Perform mechanical connection, the mechanical connection is riveting, screw connection, or directly welding the bottom plate (10f) and the connection plate (9). 6. The contact system according to claim 2, characterized in that: the hole (10e) is the center of rotation of the static contact, and is protrudingly arranged on the outer surfaces of the two side plates (10g) . 7. The contact system according to claim 2, characterized in that: the two flanges (10a) on the bracket (10) are straight or angled. 8. The contact system according to claim 3, characterized in that: the installation structure for installing the spring (7) is a spring shaft (8) for installing the spring (7) and at least one for A hole (10b) for fixing the spring shaft (8), the at least one hole (10b) for fixing the spring shaft (8) is arranged on the bracket (10) or the arc extinguishing chamber (300). 9. The contact system according to claim 3, characterized in that: the installation structure for installing the spring (7) is a groove arranged on the bracket (10) or the arc extinguishing chamber (300), and the arrangement The groove on the bracket (10) or the interrupter (300) is used to clamp the spring (7). 10. The contact system according to claim 2 or 5, characterized in that: the connecting plate (9) is connected to the static contact arm (102) through a conductor, so that they have a more ideal electrical connection performance .

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