Arc extinguish chamber structure of parallel low-voltage circuit breaker

Abstract

The utility model discloses an arc extinguish chamber structure of a parallel low-voltage circuit breaker, which comprises an arc extinguish chamber I and an arc extinguish chamber II, the arc extinguish chamber I corresponds to a moving contact I and a static contact I, the arc extinguish chamber II corresponds to a moving contact II and a static contact II, and the arc extinguish chamber structure also comprises an arc extinguish chamber III which is respectively connected with the arc extinguish chamber I and the arc extinguish chamber II in parallel, after entering the arc extinguish chamber I through the arc striking channel I, an electric arc generated by breaking the moving contact I and the static contact I can continue to pass through the arc striking channel I to be transferred into the arc extinguish chamber III to be extinguished; and after entering the arc extinguish chamber II through the arc striking channel II, the arc generated by breaking the moving contact II and the static contact II can continue to pass through the arc striking channel II to be transferred into the arc extinguish chamber III to be extinguished. By adding a common arc extinguish chamber, the number of arc extinguish grid sheets is increased, once the separation synchronism of a mechanism has deviation, current shunting is uneven, and single-stage breaking total current occurs, the arc extinguish chambers connected in parallel can still effectively extinguish breaking arcs, and the breaking performance of the switch is further improved.

Description

TECHNICAL FIELD

[0001] The utility model belongs to low pressure switch technical field, specifically speaking is related to a kind of arc chamber structure of parallel low voltage circuit breaker. BACKGROUND

[0002] Circuit breaker is the important part in distribution electrical apparatus, mainly used in industrial low voltage power system, to connect and break the current in power grid circuit and protect line and power supply equipment from the harm of overload, under voltage, short circuit, single-phase grounding and other faults.Circuit breaker breaks the function of overload or short circuit current mainly through arc chamber installed in circuit breaker.When fault current appears in circuit, and current value exceeds the set protection range of release, operating mechanism acts, and makes the moving contact and static contact of circuit breaker break rapidly, at this time, voltage between moving contact and static contact causes air medium discharge, thereby generating high-temperature arc.Arc in combustion process causes the temperature of air in arc extinguishing device to rise sharply, thereby accelerating air ionization.On the other hand, arc is separated into multiple short arcs by multiple arc separation grids under the push of magnetic field and fluid effect in arc chamber, and arc deionization effect is strengthened by metal arc separation grid, arc becomes smaller and voltage rises rapidly, so that arc is extinguished.Arc chamber of circuit breaker in arc extinguishing process hopes that arc enters arc chamber as much as possible to be extinguished, and existing large current low voltage circuit breaker is mostly small current product parallel connection, such as large shell frame circuit breaker connected in parallel by two or more small shell frame circuit breakers, for example, the structure is connected in parallel by two groups of moving contact and static contact, once the separation synchronism of mechanism exists deviation, current shunting is uneven, and in serious case, single-stage breaking full current may occur, and arc chamber in parallel in prior art is difficult to effectively extinguish breaking arc under single-stage breaking full current condition, thereby reducing breaking performance of switch. SUMMARY

[0003] The utility model aims at the defect that arc chamber in parallel is difficult to effectively extinguish breaking arc under single-stage breaking full current condition, thereby reducing breaking performance of switch, provides a kind of arc chamber structure of parallel low voltage circuit breaker, by increasing a common arc chamber, improve the arc extinguishing capacity of arc chamber of parallel low voltage circuit breaker.

[0004] In order to realize the above technical purpose, the utility model provides a kind of arc-extinguishing chamber structure of parallel low-voltage circuit breaker, it includes arc-extinguishing chamber one and arc-extinguishing chamber two, the arc-extinguishing chamber one corresponds with moving contact one and static contact one, the arc-extinguishing chamber two corresponds with moving contact two and static contact two, it is characterized by: still include arc-extinguishing chamber three that the arc-extinguishing chamber one and arc-extinguishing chamber two are parallel, the arc that moving contact one and static contact one are broken and generated can continue to be transferred to arc-extinguishing chamber three after entering arc-extinguishing chamber one by arc channel one and be extinguished;The arc that moving contact two and static contact two are broken and generated can continue to be transferred to arc-extinguishing chamber three after entering arc-extinguishing chamber two by arc channel two and be extinguished.

[0005] In one embodiment, the arc channel one and the arc channel two are connected after the arc generated by breaking the moving contact one and the static contact one is introduced into the arc-extinguishing chamber one and the arc generated by breaking the moving contact two and the static contact two is introduced into the arc-extinguishing chamber two, and the arc can be introduced into the arc-extinguishing chamber three.

[0006] In one embodiment, the arc-extinguishing chamber one and the arc-extinguishing chamber two are arranged left and right, and the arc-extinguishing chamber three and the arc-extinguishing chamber two are arranged up and down.

[0007] In one embodiment, the arc channel one includes a moving arc plate one and a static arc plate one, and the arc channel two includes a moving arc plate two and a static arc plate two.

[0008] The moving arc plate one is arranged on the side of the arc-extinguishing chamber one corresponding to the maximum breaking position of the moving contact one, and the static arc plate one is arranged on the side of the arc-extinguishing chamber one corresponding to the static contact one.

[0009] The moving arc plate one and the static arc plate one are arranged in the front and back directions and at least partially overlap the projection of the arc-extinguishing chamber one on the plane perpendicular to the front and back directions.

[0010] The moving arc plate two and the static arc plate two are arranged in the front and back directions and at least partially overlap the projection of the arc-extinguishing chamber two on the plane perpendicular to the front and back directions.

[0011] In one embodiment, the static arc plate one extends from the arc-extinguishing chamber one to the side of the arc-extinguishing chamber three corresponding to the static contact two, and the static arc plate two extends from the arc-extinguishing chamber two to the side of the arc-extinguishing chamber three corresponding to the static contact two.

[0012] The moving arc plate one extends from the arc-extinguishing chamber one to the side of the arc-extinguishing chamber three corresponding to the maximum breaking position of the moving contact two, and the moving arc plate two extends from the arc-extinguishing chamber two to the side of the arc-extinguishing chamber three corresponding to the maximum breaking position of the moving contact two.

[0013] In one of the embodiments, the static arc-guiding plate one is in contact with the static arc-guiding plate two on the side of the arc-extinguishing chamber three corresponding to the side of the static contact two opposite to the arc-extinguishing chamber one;

[0014] The static arc-guiding part formed after the contact extends to the arc-extinguishing chamber three and at least partially overlaps the projection of the arc-extinguishing chamber three on the plane in the vertical front-rear direction.

[0015] In one of the embodiments, the static arc-guiding plate one is in contact with the static arc-guiding plate two on the side of the arc-extinguishing chamber three corresponding to the side of the static contact two opposite to the arc-extinguishing chamber one;

[0016] The static arc-guiding part formed after the contact extends to the arc-extinguishing chamber three and at least partially overlaps the projection of the arc-extinguishing chamber three on the plane in the vertical front-rear direction.

[0017] In one of the embodiments, the static arc-guiding plate one is in contact with the static arc-guiding plate two on the side of the arc-extinguishing chamber three corresponding to the side of the static contact two opposite to the arc-extinguishing chamber one;

[0018] In one of the embodiments, the static arc-guiding plate one is in contact with the static arc-guiding plate two on the side of the arc-extinguishing chamber three corresponding to the side of the static contact two opposite to the arc-extinguishing chamber one;

[0019] In one of the embodiments, the static arc-guiding plate one is in contact with the static arc-guiding plate two on the side of the arc-extinguishing chamber three corresponding to the side of the static contact two opposite to the arc-extinguishing chamber one;

[0020] Advantages

[0021] The utility model provides a kind of arc extinguishing chamber structure of parallel low voltage circuit breaker, it includes arc extinguishing chamber one and arc extinguishing chamber two, the arc extinguishing chamber one is corresponding with moving contact one and static contact one, the arc extinguishing chamber two is corresponding with moving contact two and static contact two, still include arc extinguishing chamber three in parallel with the arc extinguishing chamber one and arc extinguishing chamber two respectively, the arc generated by the moving contact one and static contact one breaking passes through arc channel one and enters arc extinguishing chamber one, can continue to be transferred to arc extinguishing chamber three by arc channel one and be extinguished;The arc generated by the moving contact two and static contact two breaking passes through arc channel two and enters arc extinguishing chamber two, can continue to be transferred to arc extinguishing chamber three by arc channel two and be extinguished.A common arc extinguishing chamber is added, the number of arc extinguishing grid piece is increased, once the deviation of mechanism's separation synchronism exists, uneven current shunt appears, when single-stage breaking full current, parallel arc extinguishing chamber can still effectively extinguish breaking arc, and then improve the breaking performance of switch. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical scheme of the embodiments of the utility model, the following will be briefly introduced the drawings needed to be used in the embodiment, it should be understood that the following drawings only shows some embodiments of the utility model, therefore should not be regarded as the limitation to the scope, for ordinary skilled person in the art, under the premise of not paying creative labor, can also obtain other related drawings according to these drawings.

[0023] FIG. Figure 1 It is prior art arc extinguishing chamber installation schematic diagram;

[0024] FIG. Figure 2 It is arc extinguishing grid piece installation schematic diagram in the utility model embodiment 1 Figure 1 ;

[0025] FIG. Figure 3 It is arc extinguishing grid piece installation schematic diagram in the utility model embodiment 1 Figure 2 ;

[0026] FIG. Figure 4 It is arc extinguishing grid piece installation schematic diagram in the utility model embodiment 2 Figure 1 ;

[0027] FIG. Figure 2 It is arc extinguishing grid piece installation schematic diagram in the utility model embodiment 2 Figure 6 ;

[0028] FIG. Figure 1 It is static silver point installation schematic diagram in the utility model embodiment 2; DETAILED DESCRIPTION

[0029] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will clearly and completely explain the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort should fall into the scope of the present application.

[0030] It should be noted that when a component is referred to as being "on" or "set on" another component, it can be directly on the other component or there can be a middle component. When a component is referred to as being "connected" to another component, it can be directly connected to the other component or there can be a middle component. The terms "vertical", "horizontal", "upper", "lower", "left", "right", and similar expressions used in the description of the present application are for the purpose of illustration only and do not indicate the only orientation of the embodiments.

[0031] In addition, the terms "first", "second", and the like are used only to describe and distinguish the associated elements and are not otherwise intended to indicate or imply a relative importance or a quantity limitation of the indicated elements. Thus, a feature defined with "first" or "second" can include at least one of the feature, explicitly or implicitly. In the description of the present application, the meaning of "a plurality of" is at least two, for example, two, three, and the like, unless otherwise explicitly and specifically limited.

[0032] In the present application, unless otherwise explicitly and specifically defined, "on", "under", and "below" of a first feature to a second feature can be that the first feature is in direct contact with the second feature, or the first feature is in indirect contact with the second feature through a middle medium. Moreover, "over", "above", and "on top of" of a first feature to a second feature can be that the first feature is directly above or obliquely above the second feature, or only means that the first feature is horizontally higher than the second feature. "Under", "below", and "underneath" of a first feature to a second feature can be that the first feature is directly below or obliquely below the second feature, or only means that the first feature is horizontally lower than the second feature.

[0033] Unless otherwise defined, all technical and scientific terms used in the specification of the present application have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terms used in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. The term "and / or" used in the specification of the present application includes any and all combinations of one or more of the associated listed items.

[0034] Embodiment 1

[0035] The existing large-current low-voltage circuit breaker is mostly formed by parallel connection of small-current products, such as a large shell frame circuit breaker formed by parallel connection of two or more small shell frame circuit breakers, for example, the structure is formed by parallel connection of two sets of moving and static contacts. Once there is a deviation in the synchronization of the mechanism separation, current shunting is uneven, and in severe cases, single-stage breaking of full current may occur. As shown in the accompanying Figure 2 , the parallel connected arc extinguishing chambers in the prior art are difficult to effectively extinguish the breaking arc in the case of single-stage breaking of full current, thereby reducing the breaking performance of the switch. In order to solve this problem, as shown in the accompanying Figure 2 , the embodiment provides an arc extinguishing chamber structure of a parallel low-voltage circuit breaker, which comprises an arc extinguishing chamber one 1 and an arc extinguishing chamber two 2, the arc extinguishing chamber one 1 corresponds to a moving contact one 4 and a static contact one 5, the arc extinguishing chamber two 2 corresponds to a moving contact two 6 and a static contact two 7, and further comprises an arc extinguishing chamber three 3 connected in parallel with the arc extinguishing chamber one 1 and the arc extinguishing chamber two 2. After the arc generated by breaking of the moving contact one 4 and the static contact one 5 enters the arc extinguishing chamber one 1 through an arc channel one a, it can continue to be transferred to the arc extinguishing chamber three 3 through the arc channel one a and be extinguished. After the arc generated by breaking of the moving contact two 6 and the static contact two 7 enters the arc extinguishing chamber two 2 through an arc channel two b, it can continue to be transferred to the arc extinguishing chamber three 3 through the arc channel two b and be extinguished. In the embodiment, the direction from the moving contact at the maximum opening position to the static contact is the front-rear direction, the arc channel one a and the arc channel two b are connected after respectively introducing the arc generated by breaking of the moving contact one 4 and the static contact one 5 into the arc extinguishing chamber one 1 and the arc generated by breaking of the moving contact two 6 and the static contact two 7 into the arc extinguishing chamber two 2, and can continue to introduce the arc into the arc extinguishing chamber three 3.

[0036] In the embodiment, as shown in the accompanying Figure 2 and 3 , the arc extinguishing chamber one 1 and the arc extinguishing chamber two 2 are arranged in the left-right direction, and the arc extinguishing chamber three 3 and the arc extinguishing chamber two 2 are arranged in the up-down direction. As shown in the accompanying Figure 4 , the arc extinguishing chamber one 1 is provided with a moving arc plate one 8 on the side corresponding to the maximum breaking position of the moving contact one 4, and is provided with a static arc plate one 9 on the side corresponding to the static contact one 5. The arc extinguishing chamber two 2 is provided with a moving arc plate two 10 on the side corresponding to the maximum breaking position of the moving contact two 6, and is provided with a static arc plate two 11 on the side corresponding to the static contact two 7. The moving arc plate one 8 and the static arc plate one 9 are arranged in the front-rear direction, and at least partially coincide with the projection of the arc extinguishing chamber one 1 on the plane perpendicular to the front-rear direction. The moving arc plate two 10 and the static arc plate two 11 are arranged in the front-rear direction, and at least partially coincide with the projection of the arc extinguishing chamber two 2 on the plane perpendicular to the front-rear direction.

[0037] The static arc plate 9 extends from the arc-extinguishing chamber 1 to the side of the arc-extinguishing chamber 3 corresponding to the static contact 7, and the static arc plate 11 extends from the arc-extinguishing chamber 2 to the side of the arc-extinguishing chamber 3 corresponding to the static contact 7. The projection of the static arc plate 9 and the arc-extinguishing chamber 3 on the plane in the vertical front-rear direction at least partially overlaps; the projection of the static arc plate 11 and the arc-extinguishing chamber 3 on the plane in the vertical front-rear direction at least partially overlaps. The dynamic arc plate 8 extends from the arc-extinguishing chamber 1 to the side of the arc-extinguishing chamber 3 corresponding to the maximum breaking position of the dynamic contact 6, and the dynamic arc plate 10 extends from the arc-extinguishing chamber 2 to the side of the arc-extinguishing chamber 3 corresponding to the maximum breaking position of the dynamic contact 6. The projection of the dynamic arc plate 8 and the arc-extinguishing chamber 3 on the plane in the vertical front-rear direction at least partially overlaps; the projection of the dynamic arc plate 10 and the arc-extinguishing chamber 3 on the plane in the vertical front-rear direction at least partially overlaps. Further, the static arc plate 9 extends from the arc-extinguishing chamber 1 to the side of the arc-extinguishing chamber 3 corresponding to the static contact 7 and is in contact with the static arc plate 11, and the static arc plate 9 and the static arc plate 11 form a static arc portion m extending to the arc-extinguishing chamber 3, and the projection of the static arc portion m on the plane in the vertical front-rear direction at least partially overlaps the arc-extinguishing chamber 3.

[0038] The dynamic arc plate 8 extends from the arc-extinguishing chamber 1 to the side of the arc-extinguishing chamber 3 corresponding to the maximum breaking position of the dynamic contact 6 and is in contact with the dynamic arc plate 10, and the dynamic arc plate 8 and the dynamic arc plate 10 form a dynamic arc portion n extending to the arc-extinguishing chamber 3, and the projection of the dynamic arc portion n on the plane in the vertical front-rear direction at least partially overlaps the arc-extinguishing chamber 3.

[0039] The arc-extinguishing principle of the embodiment is as follows:

[0040] When the arc is mainly split in the arc-extinguishing chamber 1, the arc first cools and extinguishes in the arc-extinguishing chamber 1, and due to the large breaking current, the arc is guided by the static arc plate 9 to the arc-extinguishing chamber 3 for cutting and cooling, which is equivalent to increasing the heat capacity of the arc-extinguishing chamber 1.

[0041] When the arc is mainly split in the arc-extinguishing chamber 2, the arc first cools and extinguishes in the arc-extinguishing chamber 2, and due to the large breaking current, the arc is guided by the static arc plate 11 to the arc-extinguishing chamber 3 for cutting and cooling, which is equivalent to increasing the heat capacity of the arc-extinguishing chamber 2.

[0042] The arc-extinguishing grid capacity of the arc-extinguishing chamber two 2 is the same as that of the arc-extinguishing chamber one 1, and can also be different. In the embodiment, the arc-extinguishing chamber two 2 has the same arc-extinguishing grid capacity as the arc-extinguishing chamber one 1, the height between the static silver point one position where the moving contact one 4 and the static contact one 5 are in contact and the static silver point two position where the moving contact two 6 and the static contact two 7 are in contact is set to be the same, that is, there is no height difference between the two, so that the arc is simultaneously split in the arc-extinguishing chamber one 1 and the arc-extinguishing chamber two 2, so that the arc can enter the arc-extinguishing chamber three 3 under the action of the static arc plate one 9 and the moving arc plate one 8 and the static arc plate two 11 and the moving arc plate two 10, so that the cooling space of the arc-extinguishing grid is increased.

[0043] Embodiment 2

[0044] The overtravel of the moving contact one 4 is different from that of the moving contact two 6, the arc-extinguishing grid capacity in the arc-extinguishing chamber one 1 and the arc-extinguishing chamber two 2 is different, the arc-extinguishing chamber with larger arc-extinguishing grid capacity in the arc-extinguishing chamber one 1 and the arc-extinguishing chamber two 2 corresponds to the moving contact with larger overtravel in the moving contact one 4 and the moving contact two 6, and extinguishes the arc generated by larger breaking current, and the arc-extinguishing chamber with smaller arc-extinguishing grid capacity in the arc-extinguishing chamber one 1 and the arc-extinguishing chamber two 2 corresponds to the moving contact with smaller overtravel in the moving contact one 4 and the moving contact two 6, and extinguishes the arc generated by smaller breaking current.

[0045] For example, the arc-extinguishing grid capacity of the arc-extinguishing chamber two 2 is different from that of the arc-extinguishing chamber one 1, the height between the static silver point one 501 position where the moving contact one 4 and the static contact one 5 are in contact and the static silver point two 701 position where the moving contact two 6 and the static contact two 7 are in contact is set to be different, that is, the static silver point one 501 or the static silver point two 701 corresponding to the arc-extinguishing chamber two 2 and the arc-extinguishing chamber one 1 with larger arc-extinguishing grid capacity is set to be at a higher position, and corresponds to the moving contact with larger overtravel in the moving contact one 4 and the moving contact two 6, so that the contact system corresponding to the arc-extinguishing chamber two 2 and the arc-extinguishing chamber one 1 with larger arc-extinguishing grid capacity is first contacted and then disconnected, so that the arc can be cooled in the arc-extinguishing chamber with larger arc-extinguishing grid capacity first, and then enters the arc-extinguishing chamber three 3 under the action of the arc plate, so that the cooling space of the arc-extinguishing grid is also increased.

[0046] In the embodiment, as shown in FIGS. 1 to 3, the arc-extinguishing grid capacity of the arc-extinguishing chamber one 1 is greater than that of the arc-extinguishing chamber two 2, and the arc-extinguishing grid capacity of the arc-extinguishing chamber one 1 is greater than that of the arc-extinguishing chamber two 2. Figure 6 and 5 In the embodiment, as shown in FIGS. 1 to 3, the arc-extinguishing grid capacity of the arc-extinguishing chamber one 1 is greater than that of the arc-extinguishing chamber two 2, and the arc-extinguishing grid capacity of the arc-extinguishing chamber one 1 is greater than that of the arc-extinguishing chamber two 2. ​As shown, the overtravel of the movable contact one 4 corresponding to the arc chamber one 1 is greater than the overtravel of the movable contact two 6 corresponding to the arc chamber two 2, and the height position of the static silver point one 501 at the contact position of the movable contact one 4 and the static contact one 5 is set to be higher than the contact position of the movable contact two 6 and the static contact two 7, so that the contact system corresponding to the arc chamber one 1 is first contacted and then disconnected, so that the arc can be cooled in the arc chamber one 1 with large arc runner capacity first, and then enter the arc chamber one 1 and the arc chamber three 3 under the action of the static arc plate one 9 and the static arc plate two 11, so as to increase the cooling space of the arc runner.

[0047] The arc chamber structure of the parallel low-voltage circuit breaker provided by the utility model increases the number of arc runners by adding a shared arc chamber, and once there is a deviation in the separation synchronism of the mechanism, uneven current shunting occurs, and when single-stage breaking of full current is performed, the parallel arc chambers can still effectively extinguish the breaking arc, thereby improving the breaking performance of the switch.

[0048] The technical features of the above-described embodiments can be combined arbitrarily, and to make the description concise, all possible combinations of the technical features in the above-described embodiments are not described, but as long as the combinations of the technical features do not exist contradictory, they should be considered as the scope of the present application.

[0049] The above-described embodiments only express several implementation manners of the present application, and the description is relatively specific and detailed, but it should not be understood as a limitation on the patent scope of the present application. It should be pointed out that for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which all belong to the protection scope of the present application. Therefore, the patent protection scope of the present application should be subject to the appended claims.

Claims

1. An arc-extinguishing chamber structure for a parallel low-voltage circuit breaker, comprising an arc-extinguishing chamber one (1) and an arc-extinguishing chamber two (2), wherein the arc-extinguishing chamber one (1) corresponds to a moving contact one (4) and a stationary contact one (5), and the arc-extinguishing chamber two (2) corresponds to a moving contact two (6) and a stationary contact two (7), characterized in that: It also includes an arc-extinguishing chamber three (3) connected in parallel with the arc-extinguishing chamber one (1) and the arc-extinguishing chamber two (2), respectively. The electric arc generated by the breaking of the moving contact one (4) and the stationary contact one (5) enters the arc-extinguishing chamber one (1) through the arc-ignition channel one (a) and can continue to be transferred to the arc-extinguishing chamber three (3) through the arc-ignition channel one (a) to be extinguished. The electric arc generated by the breaking of the moving contact two (6) and the stationary contact two (7) enters the arc-extinguishing chamber two (2) through the arc-ignition channel two (b) and can continue to be transferred to the arc-extinguishing chamber three (3) to be extinguished.

2. The arc-extinguishing chamber structure of a parallel low-voltage circuit breaker as described in claim 1, characterized in that: The arc-initiating channel one (a) and arc-initiating channel two (b) are connected after the arc generated by the breaking of the moving contact one (4) and the stationary contact one (5) is introduced into the arc-extinguishing chamber one (1) and the arc generated by the breaking of the moving contact two (6) and the stationary contact two (7) is introduced into the arc-extinguishing chamber two (2), respectively, so that the arc can continue to be introduced into the arc-extinguishing chamber three (3).

3. The arc-extinguishing chamber structure of a parallel low-voltage circuit breaker as described in claim 1, characterized in that: The arc-extinguishing chamber one (1) and arc-extinguishing chamber two (2) are arranged side by side, and the arc-extinguishing chamber three (3) and arc-extinguishing chamber two (2) are arranged vertically.

4. The arc-extinguishing chamber structure of a parallel low-voltage circuit breaker as described in claim 1, characterized in that: The first arc-starting channel (a) includes a moving arc-starting plate (8) and a stationary arc-starting plate (9), and the second arc-starting channel (b) includes a moving arc-starting plate (10) and a stationary arc-starting plate (11). A moving arc-starting plate (8) is provided on the side of the arc-extinguishing chamber 1 (1) corresponding to the moving contact 1 (4) at the maximum breaking position; a stationary arc-starting plate (9) is provided on the side of the arc-extinguishing chamber 1 (1) corresponding to the stationary contact 1 (5); a moving arc-starting plate (10) is provided on the side of the arc-extinguishing chamber 2 (2) corresponding to the moving contact 2 (6) at the maximum breaking position; a stationary arc-starting plate (11) is provided on the side of the arc-extinguishing chamber 2 (2) corresponding to the stationary contact 2 (7); The moving arc-starting plate (8) and the stationary arc-starting plate (9) are arranged in the front-back direction and at least partially overlap with the projection of the arc-extinguishing chamber (1) on the plane perpendicular to the front-back direction; The moving arc-starting plate 2 (10) and the stationary arc-starting plate 2 (11) are arranged in the front-back direction and at least partially overlap with the projection of the arc-extinguishing chamber 2 (2) on the plane perpendicular to the front-back direction.

5. The arc-extinguishing chamber structure of a parallel low-voltage circuit breaker as described in claim 4, characterized in that: The stationary arc-starting plate 1 (9) extends from arc-extinguishing chamber 1 (1) to the side of arc-extinguishing chamber 3 (3) corresponding to stationary contact 2 (7), and the stationary arc-starting plate 2 (11) extends from arc-extinguishing chamber 2 (2) to the side of arc-extinguishing chamber 3 (3) corresponding to stationary contact 2 (7); The first moving arc-starting plate (8) extends from the first arc-extinguishing chamber (1) to the third arc-extinguishing chamber (3) on the side corresponding to the maximum breaking position of the second moving contact (6), and the second moving arc-starting plate (10) extends from the second arc-extinguishing chamber (2) to the third arc-extinguishing chamber (3) on the side corresponding to the maximum breaking position of the second moving contact (6).

6. The arc-extinguishing chamber structure of a parallel low-voltage circuit breaker as described in claim 5, characterized in that: The stationary arc-starting plate 1 (9) extends from arc-extinguishing chamber 1 (1) to arc-extinguishing chamber 3 (3) and contacts the stationary arc-starting plate 2 (11) on the side corresponding to the stationary contact 2 (7); The portion of the static arc-drawing section (m) formed after contact extends toward the arc-extinguishing chamber 3 (3) and at least partially overlaps with the projection of the arc-extinguishing chamber 3 (3) onto the plane in the vertical front-back direction.

7. The arc-extinguishing chamber structure of a parallel low-voltage circuit breaker as described in claim 5, characterized in that: The moving arc-starting plate 1 (8) extends from the arc-extinguishing chamber 1 (1) to the arc-extinguishing chamber 3 (3) and contacts the moving arc-starting plate 2 (10) on the side corresponding to the maximum breaking position of the moving contact 2 (6); The portion of the moving arc section (n) formed after contact extends toward the arc-extinguishing chamber (3) and at least partially overlaps with the projection of the arc-extinguishing chamber (3) onto the plane in the vertical front-back direction.

8. The arc-extinguishing chamber structure of a parallel low-voltage circuit breaker as described in claim 5, characterized in that: The projections of the first moving arc-starting plate (8) and the third arc-extinguishing chamber (3) on the plane in the vertical front-back direction at least partially overlap; the projections of the second moving arc-starting plate (10) and the third arc-extinguishing chamber (3) on the plane in the vertical front-back direction at least partially overlap.

9. The arc-extinguishing chamber structure of a parallel low-voltage circuit breaker as described in claim 5, characterized in that: The projections of the static arc-inducing plate 1 (9) and the arc-extinguishing chamber 3 (3) on the plane in the vertical front-back direction at least partially overlap; the projections of the static arc-inducing plate 2 (11) and the arc-extinguishing chamber 3 (3) on the plane in the vertical front-back direction at least partially overlap.

10. The arc-extinguishing chamber structure of a parallel low-voltage circuit breaker as described in claim 1, characterized in that: The overtravel of the first moving contact (4) is different from that of the second moving contact (6). The arc-extinguishing grid plates in the first arc-extinguishing chamber (1) and the second arc-extinguishing chamber (2) have different capacities. The arc-extinguishing chamber with the larger capacity of the arc-extinguishing grid plates in the first arc-extinguishing chamber (1) and the second arc-extinguishing chamber (2) corresponds to the moving contact with the larger overtravel in the first moving contact (4) and the second moving contact (6), extinguishing the arc generated by the larger breaking current. The arc-extinguishing chamber with the smaller capacity of the arc-extinguishing grid plates in the first arc-extinguishing chamber (1) and the second arc-extinguishing chamber (2) corresponds to the moving contact with the smaller overtravel in the first moving contact (4) and the second moving contact (6), extinguishing the arc generated by the smaller breaking current.

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