Circuit breaker and arc extinguishing unit

Abstract

To provide a circuit breaker having a storage part for storing a molten material generated by heat of an arc in breaking in a specific part.SOLUTION: A housing 3 including a base 1 and a cover 2, a fixed-contact 7b provided on the base 1, a movable-contact 7b opened and closed by an opening and closing mechanism 9 with respect to the fixed-contact 7a, a plurality of grid 7a for cooling an arc 18 generated when the movable-contact 11a is opened and separated, at least one grid support 11a for fixing the plurality of grid 11b, and at least one grid support 11b provided on the base 1 so as to be able to hold the grid support wall, since the arc-extinguishing insulating member 12 capable of generating gas by the heat of the arc 18 and the storage portion 13 provided on the base 1 side of the arc-extinguishing insulating member 12 and capable of storing the molten material generated by the heat of the arc 18 are provided, by storing the molten material generated by the heat of the arc 18, the molten material is sandwiched between the components that perform the opening and closing operation, and it is possible to prevent the operation failure of the components that perform the opening and closing operation.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present disclosure relates to a circuit breaker and an arc-extinguishing unit that can store molten material generated by the heat of an arc during opening and closing. [Background technology]

[0002] A circuit breaker generates heat from an arc when switching large currents such as short-circuit currents. It is known that some conventional circuit breakers use the heat from the arc to generate gas from resin parts around the switching contacts, and the pressure of the gas drives the arc toward the grid, thereby improving the circuit breaking performance (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-259434 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the conventional circuit breaker described in Patent Document 1, the heat of the arc could melt parts of the arc extinguishing device, generating molten material. This molten material moves due to the vibrations and impacts caused by the pressure at the time of breaking and the opening and closing operation of the circuit breaker, so if the molten material gets caught in the parts that perform the opening and closing operation, there is a problem that the normal opening and closing operation of the circuit breaker is hindered.

[0005] The present disclosure has been made to solve the above-mentioned problems, and provides a circuit breaker having a storage section that stores molten material generated by the heat of the arc during breaking in a specific portion. [Means for solving the problem]

[0006] The circuit breaker of the present disclosure comprises a housing consisting of a base and a cover, fixed contacts provided on the base, a movable contact that is opened and closed relative to the fixed contacts by an opening and closing mechanism, a plurality of grids that cool the arc generated when the movable contacts open and close, at least one grid support that fixes the plurality of grids, an arc-extinguishing insulating member that is provided on the base so as to be able to hold the grid support and is capable of generating gas by the heat of the arc, and a storage section that is provided on the base side of the arc-extinguishing insulating member and is capable of storing molten material generated by the heat of the arc. [Effects of the Invention]

[0007] According to the circuit breaker disclosed herein, by storing the molten material generated by the heat of the arc, it is possible to prevent the molten material from becoming trapped in the components that perform the switching operation and causing the components to malfunction. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a perspective view showing the overall configuration of a circuit breaker according to a first embodiment. [Figure 2] 1 is a perspective view showing an internal configuration of a circuit breaker according to a first embodiment. [Figure 3] FIG. 2 is a cross-sectional view showing the circuit-opening operation of the circuit breaker in the first embodiment. [Figure 4] FIG. 2 is a cross-sectional view showing a circuit closing operation of the circuit breaker in the first embodiment. [Figure 5] FIG. 10 is a diagram showing a cutting position in a cross-sectional view. [Figure 6] FIG. 2 is a perspective view of an arc-extinguishing unit according to the first embodiment. [Figure 7] 1 is a top view of the periphery of the switching contacts in the first embodiment. [Figure 8] 2 is a cross-sectional view of the periphery of the switching contact in the first embodiment. FIG. [Figure 9] FIG. 2 is a top view showing the relationship between the grid and the arc in the first embodiment. [Figure 10] FIG. 3 is a cross-sectional view showing the direction of movement of the molten material in the first embodiment. [Figure 11] 1 is a perspective view showing an arc-extinguishing insulating member according to a first embodiment. [Figure 12] FIG. 3 is a perspective view showing a second storage section in the first embodiment. [Figure 13] FIG. 10 is a perspective view showing an arc-extinguishing insulating member in a second embodiment. [Figure 14] FIG. 10 is a perspective view showing the direction of movement of the molten material in the second embodiment. [Figure 15] FIG. 11 is a perspective view showing a third storage section in the third embodiment. [Figure 16] FIG. 11 is a perspective view showing the direction of movement of the molten material in the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Embodiment 1 FIG. 1 is a perspective view showing the overall configuration of a circuit breaker according to a first embodiment, FIG. 2 is a perspective view showing the internal configuration of the circuit breaker according to the first embodiment, FIG. 3 is a cross-sectional view showing the opening operation of the circuit breaker according to the first embodiment, FIG. 4 is a cross-sectional view showing the closing operation of the circuit breaker according to the first embodiment, FIG. 5 is a diagram showing the cross-sectional position of the cross-sectional view, with cross-section AA being the cross-sectional cut position. FIG. 6 is a perspective view of an arc-extinguishing section according to the first embodiment, FIG. 7 is a top view of the periphery of the switching contacts according to the first embodiment, FIG. 8 is a cross-sectional view of the periphery of the switching contacts according to the first embodiment, and FIG. 9 is a top view showing the relationship between the grid and the arc according to the first embodiment. FIG. 10 is a cross-sectional view showing the direction of movement of the molten material according to the first embodiment, FIG. 11 is a perspective view of an arc-extinguishing insulating member, and FIG. 12 is a perspective view of a second storage section according to the first embodiment.

[0010] As shown in Fig. 1, the circuit breaker 100 is configured using a housing 3 made of an insulating material such as plastic, and consisting of a base 1 and a cover 2. The cover 2 is fitted onto the base 1 to enclose the internal components of the circuit breaker 100. Note that the base 1 and cover 2 may be fitted together in a structure other than the Z-axis direction, and may be fitted together in an X-axis direction, for example.

[0011] 2 to 5, the circuit breaker 100 is configured with, in addition to a housing 3, a handle 4 made of an insulating material such as plastic, protruding from a cover 2 so that a switching contact 7 can be operated from outside the circuit breaker 100, a power supply side terminal 5 for carrying wiring for supplying electricity to the circuit breaker 100, and a load side terminal 6 for carrying wiring for supplying electricity to the load side of the circuit breaker 100. Inside the housing 3, there are also configured: a conductive switching contact 7; a movable contact 7a of the switching contact 7 that is movable; a fixed contact 7b of the switching contact 7 that is fixed to the power supply side terminal 5 so as to be able to come into contact with the movable contact 7a; a movable contactor 8 having one end to which the movable contact 7a is fixed and the other end to which a pivot 8a is attached for operating the movable contact 7a; a switching mechanism 9 for operating the movable contactor 8; a tripping relay 10 that detects a short-circuit current or the like and performs a tripping operation; an arc extinguishing device 11 that extinguishes an arc 18 generated at the switching contact 7; and an arc-extinguishing insulating member 12. The arc-extinguishing device 11 and the arc-extinguishing insulating member 12 are combined to form an arc-extinguishing section 17 .

[0012] On the base 1, the switching contacts 7, the movable contactor 8, the tripping relay 10, and the arc extinguishing device 11 are arranged at intervals for each pole. In addition, a switching mechanism 9 is arranged in the center of the base 1 in the X-axis direction. Note that instead of the three-pole circuit breaker 100 shown in FIG. 2, a four-pole circuit breaker 100 may also be used. In the case of a four-pole circuit breaker 100, the switching mechanism 9 may not be arranged in the center of the base 1, but may be arranged shifted left and right in the X-axis direction on the plane of the paper in FIG. 2.

[0013] The metallic movable contact 7a is fixed to the movable contactor 8 at a position where it can come into contact with the fixed contact 7b. The fixed contact 7b is also made of metal and is fixed to the power supply terminal 5. It is sufficient for each pole to have at least one movable contact 7a and one fixed contact 7b. For example, a multi-contact configuration may be used in which two movable contacts 7a are fixed to the movable contactor 8 and two fixed contacts 7b are fixed to the power supply terminal 5.

[0014] The movable contactor 8 is made of a conductive metal and is connected to a switching mechanism 9 so as to be able to open and close in response to the operation of the handle 4 and the operation of the tripping relay 10. In addition, a load is applied by a pressure spring 14 so that the movable contact 7a can be pressed against the fixed contact 7b in a closed state where the movable contact 7a and the fixed contact 7b are in contact. The pressure spring 14 is made of a metal torsion spring or coil spring.

[0015] The switching mechanism 9 is made of a metal material or a resin material that has the strength and durability to be able to open and close the movable contact 8 and the movable contact 7a. Inside the switching mechanism 9, a trip bar (not shown) and the like are arranged.

[0016] The trip relay 10 is configured to be able to detect the current flowing through the circuit breaker 100 at a position where it can come into contact with the trip bar of the switching mechanism unit 9. Although it is adjacent to the load side terminal 6 in FIG. 2, it does not have to be adjacent as long as it is electrically connected.

[0017] The arc extinguishing device 11 is made of metal and is composed of multiple grids 11a, each having a V-shaped notch 11a1 in the center for opening and closing the movable contact 7a and the movable contactor 8, and legs 11a2 extending from both ends of the V-shape, and multiple grid supports 11b made of an insulating material for fixing the multiple grids 11a. The arc extinguishing device 11 is also arranged between the power supply terminal 5 and the contact point 15 of the movable contact 7a and the fixed contact 7b so that it can extinguish the arc 18 that occurs when the switching contact 7 is opened. Note that the position of the arc extinguishing device 11 is not limited to between the power supply terminal 5 and the contact point 15 of the movable contact 7a and the fixed contact 7b, as long as it can extinguish the arc 18.

[0018] 6 to 8, the grids 11a are arranged side by side at intervals between the grid supports 11b. The grids 11a are arranged diagonally so that the right side of the paper in Fig. 8 faces upward. Note that the grids 11a may be arranged closely together with no intervals between them.

[0019] The arc-extinguishing insulator 12 is made of an insulating material such as resin that generates gas due to the heat of the arc 18 and is disposed on the base 1. The arc-extinguishing device 11 is disposed above the arc-extinguishing insulator 12 in the plane of FIG. 8. The arc-extinguishing insulator 12 also includes a bottom surface (first wall surface 12a) on which multiple grid supports 11b are disposed, a front wall surface (second wall surface 12b) that prevents molten material generated by the heat of the arc 18 from scattering toward the switching mechanism 9 or the pivot shaft 8a of the movable contact 8, and a side wall surface (third wall surface 12c) that is disposed between the grid supports 11b and the movable contact 8 in the X-axis direction of FIG. 7 and that combines with the second wall surface 12b to form an L-shape as viewed from the plane of FIG. 7. The first wall surface 12a, the second wall surface 12b, and the third wall surface 12c can be combined to form a first storage section 13a shown in FIG. 11 that prevents molten material from moving toward the switching mechanism 9 and the switching contact 7. The first storage portion 13a may be located in a position surrounding both leg portions 11a2 of the plurality of grids 11a, or may be located in a position away from both leg portions 11a2 toward the load side terminal 6.

[0020] Although the grid supports 11b shown in Figure 6 are two, they may be connected at the power supply terminals 5, i.e., at least one grid support 11b may be formed by bending a single plate. Also, instead of a bent plate, a U-shape made of resin material may be used.

[0021] In addition, the arc-extinguishing insulating member 12 may be extended upward along the Z axis in the plane of the paper in Figure 8 to provide a new wall surface equivalent to the grid support 11b, and multiple grids 11a may be fixed to the arc-extinguishing insulating member 12, thereby eliminating the grid support 11b.

[0022] As shown in Figure 12, a second storage section 13b can be configured that can store a wider range of molten material than the first storage section 13a described above by combining at least one of multiple grid supports 11b in addition to the first wall surface 12a, second wall surface 12b, and third wall surface 12c to surround the second storage section 13b on all four sides. That is, the second storage section 13b is surrounded on all four sides by the first wall surface 12a on the first side, the second wall surface 12b on the second side, the third wall surface 12c on the third side, and the grid support 11b on the fourth side. Here, for the sake of explanation, the grid support 11b and multiple grids 11a on the left side of Figure 9 are not shown.

[0023] The arc-extinguishing insulating member 12 may be omitted, and the first storage unit 13a may be configured with the base 1. In the case of configuring with the base 1, for example, if the base 1 protrudes upward in the plane of the paper in Fig. 4 in the same shape as the omitted arc-extinguishing insulating member 12, and the arc-extinguishing device 11 is disposed on this protruding shape, it can be configured similarly to the first storage unit 13a. The arc-extinguishing insulating member recited in claim 1 includes both the meaning of the arc-extinguishing insulating member 12 that is separate from the base 1 and the meaning of the base 1 that is provided with the function of the arc-extinguishing insulating member 12.

[0024] Next, the operation of the circuit breaker 100 will be described.

[0025] The circuit-opening operation of the circuit breaker 100 shown in Figure 3 will now be described. By operating the handle 4 so that the tip of the handle 4 faces the load-side terminal 6 along the Y axis, the movable contactor 8 and the movable contact 7a are lifted, the movable contact 7a and the fixed contact 7b are separated, and continuity in the circuit breaker 100 is lost. In this circuit-opening operation, the movable contact 7a and the fixed contact 7b are maintained in an open state.

[0026] The closing operation of the circuit breaker 100 shown in Figure 4 will now be described. By operating the handle 4 so that the tip of the handle 4 points in the direction of the power supply side terminal 5 along the Y axis, the movable contactor 8 and the movable contact 7a are pushed toward the base 1, and the fixed contact 7b and the movable contact 7a come into contact with each other, thereby conducting the circuit breaker 100. During this closing operation, the fixed contact 7b and the movable contact 7a are maintained in contact with each other.

[0027] When the movable contact 7a comes into contact with the fixed contact 7b, the electrical circuit between the power supply terminal 5 and the load terminal 6 becomes conductive, and when the movable contact 7a separates from the fixed contact 7b, the electrical circuit between the power supply terminal 5 and the load terminal 6 is interrupted.

[0028] Next, the tripping operation of the circuit breaker 100 will be described. When a current of a predetermined value or more, such as a short-circuit current or an overcurrent, flows through the circuit breaker 100 in the closed state, the trip relay 10 rotates, pushing a trip bar (not shown) provided on the switching mechanism 9, which drives the switching mechanism 9 and causes the movable contact 8 to rotate around the rotation axis 8a shown in FIG. 8 in the direction toward the closed state. The rotation of the movable contact 8 separates the movable contact 7a from the fixed contact 7b. When the movable contact 7a separates, an arc 18 caused by the flowing current attempts to maintain the shortest distance between the separated fixed contact 7b and moving contact 7a.

[0029] At this time, magnetic flux 19 generated by the current of arc 18 flows around arc 18 shown in FIG. 9. When this magnetic flux 19 passes through the multiple grids 11a, a bias in magnetic flux 19 occurs. When magnetic flux 19 passes through the notches 11a1 provided in the multiple grids 11a, the bias in magnetic flux 19 becomes even greater. Because arc 18 is driven toward the center of this biased magnetic flux 19, arc 18 is magnetically driven toward the back space (the right side of the paper in FIG. 9). In addition, the heat of arc 18 generates arc-extinguishing gas from arc-extinguishing insulating member 12, and the pressure of this gas also drives arc 18 toward power supply terminal 5. As arc 18 moves, it is divided into short arcs 18 between the multiple grids 11a by the multiple grids 11a. A voltage drop occurs in the divided arc 18, and the voltage of arc 18 to maintain arc 18 rises. When the voltage becomes higher than the power supply voltage, arc 18 is extinguished. Here, the arc 18 is at a high temperature of 1000°C or more.

[0030] Next, the influence of the heat of the arc 18 will be described. The arc 18 moves from left to right on the plane of FIG. 8. When the arc 18 comes into contact with at least one of the grids 11a, the heat of the arc 18 melts the metal grid 11a. At this time, the arc 18 moves toward the power supply terminal 5, so the temperature inside the arc extinguishing device 11 is higher on the power supply terminal 5 side and lower on both leg portions 11a2 side. Therefore, the pressure that moves the molten material is a force directed from the higher temperature side to the lower temperature side, and after arc 18 is driven to the right side of the paper in Fig. 8, the molten material generated in the part that arc 18 passed through flows due to the pressure generated from arc 18, which has a higher temperature, toward the left side of the paper in Fig. 8, which has a lower temperature. Arrow L in Fig. 10 shows an example of the movement of the molten material.

[0031] Here, the molten material, which is a part of the melted grid 11a, flows along the multiple grids 11a, the first wall surface 12a, the second wall surface 12b, or the third wall surface 12c to the first storage section 13a or the second storage section 13b. This prevents the molten material from getting caught in the crossbar (not shown) provided on the base 1 side of the switching mechanism section 9, the movable contactor 8, or the switching contacts 7, thereby preventing the molten material from interfering with the switching operation of the circuit breaker 100. The molten material of the multiple grids 11a accumulated in the first storage section 13a or the second storage section 13b solidifies and becomes immobile as the temperature inside the arc extinguishing device 11 drops, and therefore can be kept in the first storage section 13a or the second storage section 13b.

[0032] Furthermore, since the first wall surface 12a is provided closer to the base 1 than the plurality of grids 11a, even if molten material occurs on any of the plurality of grids 11a, it can be received by the first wall surface 12a.

[0033] The arc-extinguishing insulating member 12 is made of an insulating material such as resin, so that even if the arc 18 comes into contact with the arc-extinguishing insulating member 12, no melting occurs.

[0034] Furthermore, by making the angle between the first wall surface 12a and the second wall surface 12b an acute angle, the molten material adhering to the first wall surface 12a can be quickly collected in the first storage section 13a or the second storage section 13b by gravity.

[0035] Furthermore, by configuring the second wall surface 12b of the arc-extinguishing insulating member 12 to be higher than the highest point 11a3 of both leg portions 11a2 of the multiple grids 11a on the Z axis in Figure 8, i.e., the both leg portions 11a2 that are farthest from the first wall surface 12a, it is possible to better prevent the molten material generated in the grid 11a from flowing or scattering toward the opening and closing mechanism unit 9, or to increase the area over which the molten material that flows or scatters toward the opening and closing mechanism unit 9 can be collected in the first storage unit 13a or the second storage unit 13b.

[0036] According to the first embodiment, the circuit breaker includes a housing 3 consisting of a base 1 and a cover 2, a fixed contact 7b provided on the base 1, a movable contact 7a that is opened and closed by an opening / closing mechanism unit 9 relative to the fixed contact 7b, a plurality of grids 11a that cool an arc 18 that is generated when the movable contact 7a opens and closes, at least one grid support 11b that fixes the plurality of grids 11a, an arc-extinguishing insulator 12 that is provided on the base 1 to be able to hold the grid support 11b and that is capable of generating gas by the heat of the arc 18, and a storage unit 13 that is provided on the base 1 side of the arc-extinguishing insulator 12 and is capable of storing molten material generated by the heat of the arc 18. Therefore, the molten material generated on the plurality of grids 11a by the heat of the arc 18 remains in the storage unit 13 provided in the arc-extinguishing insulator 12, and therefore the molten material can be prevented from interfering with the opening and closing operation of the circuit breaker 100.

[0037] Embodiment 2 In the first embodiment, the first wall surface 12a of the arc-extinguishing insulating member 12 is flat, but in the second embodiment, a groove 16 is provided in the first wall surface 12a of the arc-extinguishing insulating member 12.

[0038] As shown in Fig. 13, a groove 16 is provided in the center of the first wall surface 12a of the arc-extinguishing insulating member 12 in embodiment 2. The melted material of the plurality of grids 11a generated by the heat of the arc 18 at the time of interruption moves on the groove 16 as indicated by the arrow M in Fig. 14 and can be stored in the first storage section 13a or the second storage section 13b.

[0039] According to the second embodiment, in addition to the effects shown in the first embodiment, the groove 16 is provided on the first wall surface 12a of the arc-extinguishing insulating member 12, so that the molten material of the plurality of grids 11a generated by the heat of the arc 18 can easily flow into the first storage section 13a or the second storage section 13b, that is, the molten material can be prevented from flowing in the direction of the fixed contact 7b. Therefore, compared to the first embodiment, it is possible to prevent the molten material of the plurality of grids 11a generated by the heat of the arc 18 from being caught between the components that perform the switching operation, thereby preventing the circuit breaker 100 from malfunctioning.

[0040] Embodiment 3 In the first embodiment, the first storage section 13a or the second storage section 13b is provided on the base 1 side of the arc-extinguishing insulator 12, but in the third embodiment, a storage section 13, i.e., a third storage section 13c, is also provided on the cover 2 side of the arc-extinguishing insulator 12. Here, the second wall surface 12b and the third wall surface 12c extend toward the cover 2 while maintaining the positions in the first embodiment.

[0041] As shown in FIG. 15, fourth wall 12d and fifth wall 12e are provided on the cover 2 side of arc-extinguishing insulating member 12 in embodiment 3, and these walls, combined with grid support 11b, form third storage section 13c. Molten material generated by the heat of arc 18 moves as indicated by arrow N in FIG. 16 due to pressure caused by the heat of arc 18 and can be stored in third storage section 13c. An additional wall parallel to second wall 12b may be provided on the power supply terminal 5 side of third storage section 13c, forming third storage section 13c that surrounds the third storage section 13c in five directions. In other words, in this case, only the base 1 side of third storage section 13c has no wall.

[0042] According to the third embodiment, even when the circuit breaker 100 is mounted on the ceiling of an electrical installation, i.e., when the base 1 and the cover 2 are mounted upside down on the Z axis in FIG. 3, it is possible to prevent the molten material of the multiple grids 11a generated by the heat of the arc 18 from getting caught in the cover 2 and the handle 4 and interfering with the operation of the opening and closing mechanism 9.

[0043] The configurations shown in the above embodiments are examples of the contents of the present disclosure. The embodiments can be combined with other known technologies. Part of the configurations of the embodiments can be omitted or modified without departing from the gist of the present disclosure.

[0044] The configuration of the present disclosure is not limited to the circuit breaker 100, but can also be applied to an electromagnetic contactor or a smart meter, as long as the electrical equipment generates molten material due to the heat of the arc 18 generated between the switching contacts when current is interrupted. [Explanation of symbols]

[0045] 1 Base, 2 Cover, 3 Housing, 4 Handle, 5 Power terminal, 6 load side terminal, 7 switching contact, 7a movable contact, 7b fixed contact 8 moving contact, 8a rotating shaft, 9 opening / closing mechanism, 10 tripping relay, 11 arc extinguishing device, 11a grid, 11a1 notch, 11a2 both legs, 11a3 Highest point, 11b Grid support, 12 Arc-extinguishing insulating member, 12a first wall, 12b second wall, 12c third wall, 12d fourth wall, 12e fifth wall, 13 reservoir, 13a first storage section, 13b second storage section, 13c third storage section, 14 contact pressure spring, 15 contact point, 16 groove, 17 arc extinguishing part, 18 arc, 19 magnetic flux, 100 circuit breakers.

Claims

1. a housing consisting of a base and a cover; a fixed contact provided on the base; a movable contact that is opened and closed by a switching mechanism relative to the fixed contact; a plurality of grids for cooling arcs generated when the movable contacts are opened; at least one grid support for securing the plurality of grids; an arc-extinguishing insulating member that is provided on the base so as to be able to hold the grid support and that is capable of generating gas by heat of the arc; a storage section provided on the base side of the arc-extinguishing insulating member and capable of storing a molten material generated by heat of the arc; A circuit breaker comprising:

2. 2. The circuit breaker according to claim 1, wherein the storage section is surrounded on three sides by a combination of a first wall surface capable of holding the grid support provided on the arc-extinguishing insulating member, a second wall surface intersecting with the first wall surface on the opening / closing mechanism section side, and a third wall surface intersecting with the first wall surface and the second wall surface.

3. 3. The circuit breaker of claim 2, wherein the reservoir comprises a second reservoir in combination with and surrounded on four sides by the first reservoir and the grid support.

4. The plurality of grids have a notch on the movable contact side, and legs are formed on both sides of the notch, The circuit breaker according to claim 3 , wherein the second wall surface of the arc-extinguishing insulating member is higher than the two legs furthest from the first wall surface.

5. The circuit breaker according to claim 4 , wherein the arc-extinguishing insulating member is configured such that the angle between the first wall surface and the second wall surface is an acute angle.

6. The circuit breaker according to any one of claims 1 to 5, wherein the arc-extinguishing insulating member has a groove on the first wall surface.

7. The circuit breaker according to claim 6, wherein one end of the second wall surface of the arc-extinguishing insulating member intersects with the first wall surface, and the other end of the arc-extinguishing insulating member has a reservoir.

8. a plurality of grids for cooling the arc, each grid having a notch and legs formed on either side of the notch; at least one grid support for securing the plurality of grids; an arc-extinguishing insulating member on which the grid support can be installed; an arc-extinguishing unit provided in the arc-extinguishing insulating member and capable of storing molten material generated by the heat of the arc;

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