circuit breaker

Abstract

A circuit breaker (100) has a handle (2), an engagement pin (3), a first arm (4), a latch (5), a latch spring (6), a movable member (7), a fixed member (8), an arc chamber (10), an arc rolling ring (11), an electromagnet portion (13), and a second arm (14). The electromagnet portion (13) drives an actuator (13g) in the event of a short-circuit current flowing in the circuit. The second arm (14) drives the latch (5) against the pre-tightening force of the latch (5) generated by the latch spring (6) in the event that the actuator (13g) is driven, releasing the engagement of the engagement pin (3) and the first arm (4). Furthermore, the second arm (14) rotates about a rotation shaft (15), and the distance between the abutting position of the latch (5) and the rotation shaft (15) is longer than the distance between the position pressed by the driving of the actuator (13g) and the rotation shaft (15).

Description

Technical Field

[0001] The present invention relates to a circuit breaker for interrupting an electric circuit in the event that a short-circuit current flows. Background Art

[0002] A circuit breaker is known that performs a circuit breaking operation to break the circuit when a large current such as a short-circuit current flows through the circuit. In this circuit breaker, during the circuit breaking operation, it is required to quickly separate the movable contact from the fixed contact to extinguish the arc generated between these contacts.

[0003] Conventional circuit breakers typically include an electromagnet that uses this high current to drive an actuator in order to quickly separate the movable contact from the fixed contact during a circuit-breaking operation. Furthermore, in circuit breakers, the arc generated between the fixed and movable contacts is extinguished in an arc extinguishing chamber, but this requires directing the arc into the chamber. Known methods for directing the arc into the arc extinguishing chamber include surrounding the contacts with an arc extinguishing chamber and arc propagation methods that move the arc generated between the contacts toward an arc extinguishing chamber located farther away.

[0004] In the case of small circuit breakers often used in distribution boards and the like, due to restrictions on cost and external dimensions, a circuit breaker generally has a structure that combines an electromagnet portion with an arc propagation method, as described in Patent Document 1.

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 7-226143

[0006] In a circuit breaker that adopts an arc travel method, since there is no arc extinguishing chamber around the contacts to extinguish the arc, in order to make the arc generated during the circuit breaker action move quickly from the contact part to the arc extinguishing chamber, it is preferable to further increase the contact separation speed and separation distance. Summary of the Invention

[0007] The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to obtain a circuit breaker capable of further increasing the opening speed and opening distance of contacts during a circuit breaking operation.

[0008] In order to solve the above-mentioned problems and achieve the purpose, the circuit breaker of the present invention comprises a handle, a locking pin, a first arm, a spring, a spring spring, a movable part, a fixed part, an arc extinguishing chamber, an arc runner, an electromagnet part and a second arm. The handle is operated by a user. The locking pin is rotatably mounted on the handle. The first arm is engaged with the locking pin and moves in conjunction with the movement of the locking pin. The spring maintains the engagement between the first arm and the locking pin. The spring spring pre-tightens the spring in the direction in which the spring maintains the engagement between the first arm and the locking pin. The movable part is mounted on the first arm and has a movable contact. The fixed part has a fixed contact that contacts the movable contact. The arc extinguishing chamber extinguishes the arc generated between the movable contact and the fixed contact when the movable contact separates from the fixed contact. The arc runner moves the arc toward the arc extinguishing chamber. The electromagnet part drives the actuator when a short-circuit current flows in the circuit. When the actuator is driven, the second arm drives the latch against the latch's preload force generated by the latch spring, thereby releasing the engagement between the engaging pin and the first arm. The second arm rotates about the rotation axis, and the distance between the position where the latch contacts the rotation axis is longer than the distance between the position where the latch is pressed by the actuator and the rotation axis.

[0009] Effects of the Invention

[0010] According to the present invention, there is an effect that the opening speed and opening distance of the contacts can be further increased during the circuit breaking operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a diagram showing an example of the internal structure of the circuit breaker according to the first embodiment when it is in the closed state.

[0012] Figure 2 This is a diagram showing an example of the structure of the electromagnet portion according to the first embodiment.

[0013] Figure 3 A side view showing an example of the structure of the second arm according to the first embodiment

[0014] Figure 4 This is a front view showing an example of the structure of the second arm involved in embodiment 1.

[0015] Figure 5 It is along Figure 4 Cross-sectional view of line V-V shown

[0016] Figure 6 This is a diagram showing an example of the internal structure of the circuit breaker according to the first embodiment when it is in the open state.

[0017] Figure 7 This is a perspective view showing an example of the internal structure of the circuit breaker according to the first embodiment when it is in the OFF state. DETAILED DESCRIPTION

[0018] Hereinafter, the circuit breaker according to the embodiment will be explained in detail based on the drawings.

[0019] Embodiment 1

[0020] Figure 1 is a drawing showing one example of the internal structure of the circuit breaker according to Embodiment 1 in a case where the circuit breaker is in a closed state. In Figure 1 the drawing, a three-dimensional orthogonal coordinate system including a Z axis in which the upper side in the paper is taken as a positive direction is shown for the sake of easy understanding of the explanation. The orthogonal coordinate system is also shown in other drawings used in the following explanation, and in a case where only a part of the structure of the circuit breaker is shown in the drawing, the directions of the X axis, the Y axis, and the Z axis are directions shown in a state where the circuit breaker is assembled. Hereinafter, the direction of the Z axis will be sometimes referred to as the up-and-down direction, the positive direction of the Z axis will be sometimes referred to as the upward direction, and the positive direction of the X axis will be sometimes referred to as the rightward direction. Figure 1

[0021] Figure 1 The circuit breaker 100 shown in the drawing becomes a disconnected state from the closed state through a current breaking operation in a case where a short-circuit current or an overcurrent flows in a circuit. The closed state is a state where the circuit is connected by the circuit breaker 100, and is a state where a current flows in the circuit. The disconnected state is a state where the circuit is disconnected by the circuit breaker 100, and is a state where a current does not flow in the circuit.

[0022] The circuit breaker 100 has a frame 1, a handle 2, an engagement pin 3, a first arm 4, a latch 5, a latch spring 6, a movable member 7, a fixed member 8, a main spring 9, an arc chamber 10, an arc rolling ring 11, an overload detection device 12, an electromagnet portion 13, and a second arm 14.

[0023] The frame 1 is formed of an insulating member, and has an opening la in a front surface. The handle 2 is operated by a user in order to set the circuit breaker 100 from the disconnected state to the closed state or from the closed state to the disconnected state. The handle 2 has an operation portion 2a which protrudes from the opening la, a rotation portion 2c which is rotated about a rotation axis 2b by the operation of the user to the operation portion 2a, and a protrusion portion 2d which protrudes from the rotation portion 2c.

[0024] The engagement pin 3 is rotatably attached to the protrusion portion 2d of the handle 2. The engagement pin 3 is formed in a U shape, for example, and is also called a U pin. The shape of the engagement pin 3 is not limited to the U shape. The first arm 4 is rotatably supported to a frame fixed to the frame 1, and a base end portion is engaged with the engagement pin 3. The first arm 4 is linked with the operation of the engagement pin 3 in a state where the base end portion is engaged with the engagement pin 3.​

[0025] The latch 5 has a retaining portion 5a that maintains the engagement between the first arm 4 and the engagement pin 3, and an abutting portion 5b that abuts against the second arm 14. The latch 5 is rotatably supported on a frame fixed to the frame body 1. The latch spring 6 preloads the latch 5 in the direction in which the latch 5 maintains the engagement between the first arm 4 and the engagement pin 3. The direction in which the latch spring 6 preloads the latch 5 is Figure 1 in the counterclockwise direction.

[0026] The base end of the movable member 7 is fixedly attached to the front end of the first arm 4, and has a movable contact 7a at the front end. The fixed member 8 has a fixed contact 8a that contacts the movable contact 7a. Figure 1 In the example shown, the movable element 7 is formed into a crank shape. In addition, the base end portion of the fixed contact 8a is fixedly attached to the electromagnet portion 13, and the front end portion is formed into a U shape.

[0027] Main spring 9 in Figure 1 Pre-tighten the first arm 4 clockwise. Figure 1 In the state shown, the handle 2 is in a position for controlling the circuit breaker 100 to be in the closed state, and the first arm 4 and the engaging pin 3 are engaged by the retaining portion 5a of the latch 5, so that the movable contact 7a and the fixed contact 8a are in contact, and the circuit breaker 100 is in the closed state.

[0028] Arc extinguishing chamber 10 extinguishes an arc generated between movable contact 7a and fixed contact 8a when movable contact 7a is separated from fixed contact 8a. Arc runner 11 moves the arc generated between movable contact 7a and fixed contact 8a toward arc extinguishing chamber 10.

[0029] The overload detection device 12 is composed of a bimetallic member, for example. If an overcurrent flows, it bends due to self-heating. When the bending reaches a predetermined amount, it acts on the latch 5, and as described later, the movable contact 7a is separated from the fixed contact 8a.

[0030] The electromagnet unit 13 drives the actuator 13g when a short-circuit current flows through the circuit. The second arm 14 operates in conjunction with the actuator 13g. The structure and operation of the electromagnet unit 13 and the second arm 14 will be described in detail later.

[0031] When the circuit breaker 100 is in the open state, if the user rotates the handle 2 to the position where the circuit breaker 100 is in the closed state, the first arm 4 connected to the handle 2 via the engagement pin 3 rotates, and the movable member 7 rotates along with the rotation of the first arm 4. As a result, the movable contact 7a and the fixed contact 8a come into contact, forming a closed state. Figure 1 In the state shown, the circuit is in a closed state. When the circuit breaker 100 is in the closed state, current can flow in the circuit.

[0032] In addition, the circuit breaker 100 is Figure 1 In the state shown, if an overcurrent flows through the circuit, the overload detection device 12 bends due to self-heating. When this bending reaches a predetermined amount, the force exceeding the preload of the latch spring 6 actuates the latch 5. This disengages the first arm 4 from the engaging pin 3, and the force of the main spring 9 separates the movable contact 7a from the fixed contact 8a. Consequently, the circuit breaker 100 enters the OFF state.

[0033] In addition, the circuit breaker 100 is Figure 1 In the state shown, if a short-circuit current flows through the circuit, the electromagnet portion 13 and second arm 14 disengage the first arm 4 from the engagement pin 3, and the force of the main spring 9 separates the movable contact 7a from the fixed contact 8a. As a result, the circuit breaker 100 enters the OFF state. The electromagnet portion 13 and second arm 14 will be described in detail below.

[0034] First, the electromagnet portion 13 will be described. Figure 2 1 is a diagram showing an example of the structure of the electromagnet portion involved in the first embodiment. Figure 2 As shown, the electromagnet portion 13 includes a coil 13a, yokes 13b and 13c, a pipe 13d, a fixed iron core 13e, a movable iron core 13f, an actuator 13g, and a hook 13h.

[0035] The yokes 13b and 13c are made of magnetic material, and the fixed core 13e and movable core 13f are made of conductive materials such as iron. One end of the actuator 13g is fixed to the movable core 13f, and one end of the hook 13h is fixed to the other end of the actuator 13g.

[0036] Hook 13h Figure 2 As shown, the hook 13h is formed into an L-shape. The hook 13h includes a first extension portion 13h1 extending orthogonally to the direction of movement of the movable iron core 13f and in an upward direction toward the handle 2; and a second extension portion 13h2 extending in the direction of movement of the movable iron core 13f and away from the movable iron core 13f. The first extension portion 13h1 is fixed to the other end of the actuator 13g.

[0037] The coil 13a is connected to the fixing member 8 and constitutes a part of the circuit between the power supply side conductor and the load side conductor in the circuit breaker 100. When a short-circuit current flows through the coil 13a, a magnetic flux is generated.

[0038] The magnetic flux generated by the short-circuit current flowing through coil 13a passes through yokes 13b and 13c, penetrating fixed core 13e and movable core 13f housed in tube 13d. This magnetizes fixed core 13e and movable core 13f, attracting movable core 13f toward fixed core 13e. Furthermore, as described above, actuator 13g is fixed to movable core 13f, and hook 13h is fixed to actuator 13g. Therefore, actuator 13g and hook 13h also move toward fixed core 13e.

[0039] The movable iron core 13f is preloaded in a direction away from the fixed iron core 13e by a preload unit (not shown). Unless a large current flows to generate a magnetic force in the coil 13a, the movable iron core 13f does not move toward the fixed iron core 13e. The preload unit (not shown) is, for example, a cylindrical coil spring disposed within the tube 13d.

[0040] Next, the structure of the second arm 14 will be described. Figure 3 This is a side view showing an example of the structure of the second arm according to the first embodiment. Figure 4 This is a front view showing an example of the structure of the second arm according to the first embodiment. Figure 5 It is along Figure 4 A cross-sectional view taken along line V-V is shown.

[0041] Figures 3 to 5 The second arm 14 shown is formed of an insulating member such as resin, but may be formed of a material other than an insulating member. The second arm 14 has an extension portion 14a and a contact portion 14b. Figure 1 The device rotates about the rotation axis 15 shown.

[0042] The extension portion 14a extends in the vertical direction when the circuit breaker 100 is in the closed state, and the middle portion is rotatably supported on the Figure 1 The base end of the extension portion 14a is rotatably connected to the hook 13h of the electromagnet portion 13. The distal end of the extension portion 14a is continuous with the base end of the contact portion 14b. The contact portion 14b has a shape that expands from the base end toward the distal end in a direction perpendicular to the extension direction of the rotational shaft 15 and is formed into a semicircular shape when viewed from the extension direction of the rotational shaft 15.

[0043] In addition, the contact portion 14b has Figure 1The abutment surface 14b1, against which the abutment portion 5b of the latch 5 abuts, is formed in an arcuate shape. Furthermore, a notch 14b2 is formed at the front end of the abutment portion 14b, at a position opposite the movable member 7. This notch 14b2 is formed at the center of the front end of the abutment portion 14b, in the direction in which the rotation axis 15 extends. Furthermore, the abutment portion 14b has an upwardly recessed concave space 14c within it. Furthermore, the length of the abutment portion 14b in the direction in which the rotation axis 15 extends is longer than the length of the movable contact 7a and the fixed contact 8a in the direction in which the rotation axis 15 extends.

[0044] Next, the operation of the electromagnet portion 13 and the second arm 14 will be described. Figure 6 This is a diagram showing an example of the internal structure of the circuit breaker according to the first embodiment when it is in the open state.

[0045] The circuit breaker 100 is Figure 1 In the state shown in FIG. 1 , if a short-circuit current flows in the circuit, the electromagnet portion 13 drives the actuator 13g, and the actuator 13g and the hook 13h move to Figure 1 The second arm 14 is rotatably connected to the hook 13h. Therefore, when the actuator 13g is driven, the second arm 14 moves in the right direction. Figure 1 The latch 5 rotates clockwise in the middle of the latch, counteracting the preload force of the latch 5 generated by the latch spring 6 and causing the latch 5 to Figure 1 Rotate clockwise.

[0046] Furthermore, if the engagement between the first arm 4 and the engagement pin 3 is released, the movable contact 7a is separated from the fixed contact 8a by the force of the main spring 9, as shown in FIG. Figure 6 As shown, the circuit breaker 100 is in the OFF state. As described above, the second arm 14 has the cutout portion 14b2 formed therein, and the cutout portion 14b2 prevents the second arm 14 from contacting the movable element 7 when the second arm 14 rotates.

[0047] like Figure 6 As shown, the distance L2 between the position where the second arm 14 contacts the latch 5 and the rotation axis 15 is longer than the distance L1 between the position where the second arm 14 is pressed by the drive of the actuator 13g and the rotation axis 15. As a result, the latch 5 side of the second arm 14 can rotate the latch 5 at a faster operating speed than the operating speed of the movable iron core 13f generated by the electromagnet portion 13.

[0048] Furthermore, in the circuit breaker 100, a large operating stroke can be generated at the position where the second arm 14 contacts the latch 5, even without increasing the operating stroke of the actuator 13g of the electromagnet portion 13. Since the first arm 4 rotates in conjunction with the rotation of the latch 5, the circuit breaker 100 can increase the travel distance of the first arm 4 and the travel distance of the movable element 7 fixed to the first arm 4. Therefore, in the circuit breaker 100, the separation distance between the movable contact 7a and the fixed contact 8a can be increased without increasing the size of the electromagnet portion 13.

[0049] In the above example, the position pressed by the drive of the actuator 13g is the connection point between the hook 13h and the second arm 14. However, the present invention is not limited to this example. For example, in the case of a structure in which the second arm 14 and the actuator 13g are directly connected, the position pressed by the drive of the actuator 13g is the connection point between the actuator 13g and the second arm 14.

[0050] In addition, the second arm 14 may also be configured to Figure 1 The status shown starts at Figure 1 When the second arm 14 rotates clockwise, the second arm 14 engages with the first arm 4. Thus, in addition to the force of the main spring 9, the movable contact 7a can be separated from the fixed contact 8a by the rotational force of the second arm 14.

[0051] Figure 7 1 is a perspective view showing an example of the internal structure of the circuit breaker according to the first embodiment when it is in the OFF state. Figure 7 In FIG. 1 , the arc 16 generated between the movable contact 7a and the fixed contact 8a during the circuit breaker operation is simply shown. Figure 7 As shown, the contact portion 14b of the second arm 14 is arranged to face the movable contact 7a and the fixed contact 8a, covering the upper sides of the movable contact 7a and the fixed contact 8a. Therefore, arc gas or molten material generated during the circuit breaking operation can be prevented from flying toward and adhering to internal mechanisms such as the first arm 4 and the latch 5, thereby suppressing degradation in the performance of the circuit breaker 100 after interrupting the short-circuit current.

[0052] To minimize the adhesion of arc gas, molten material, and the like, it is preferable that the second arm 14 extend until the movable element 7 and the fixed element 8 reach their respective limits. However, if the second arm 14 is formed of metal, the insulation distance may be insufficient. By forming the second arm 14 from an insulating member, the second arm 14 can be extended until the movable element 7 and the fixed element 8 reach their respective limits. Therefore, by forming the second arm 14 from an insulating member, the adhesion of arc gas, molten material, and the like can be further suppressed compared to when the second arm 14 is formed of metal.

[0053] Furthermore, to prevent arc gas, molten material, and the like from flying into the internal mechanism via the second arm 14, the contact portion 14b of the second arm 14 is preferably designed to be the same size as the internal width dimension of the circuit breaker 100 in the direction in which the rotating shaft 15 extends. However, if the dimensions are identical, the second arm 14 cannot rotate. Therefore, the length of the contact portion 14b of the second arm 14 in the direction in which the rotating shaft 15 extends is preferably designed to be as close as possible to the internal width dimension of the circuit breaker 100, without hindering rotational movement. The width dimension refers to the length in the direction in which the rotating shaft 15 extends. For example, the length of the contact portion 14b in the direction in which the rotating shaft 15 extends is preferably set to at least 0.9 times the internal length of the rotating shaft 15 in the direction in which the rotating shaft 15 extends.

[0054] Furthermore, the contact portion 14b of the second arm 14 has an upwardly recessed space 14c therein, and the facing surfaces 14d of the fixed contact 8a and the movable contact 7a are formed in a concave shape. This allows the second arm 14 to more effectively prevent arc gas or molten material from flying into the internal mechanism.

[0055] The second arm 14 is not limited to any shape as long as it can suppress arc gas or molten material from flying toward the internal mechanism. Figures 3 to 5 The shape shown may be configured without the cutout 14b2 and the concave space 14c. For example, the second arm 14 may be configured to abut against the first arm 4 in addition to the latch 5, so that both the latch 5 and the first arm 4 rotate.

[0056] As described above, the circuit breaker 100 according to Embodiment 1 has a handle 2, an engagement pin 3, a first arm 4, a latch 5, a latch spring 6, a movable element 7, a fixed element 8, an arc chamber 10, an arc rolling ring 11, an electromagnet portion 13, and a second arm 14. The handle 2 is operated by a user. The engagement pin 3 is rotatably installed to the handle 2. The first arm 4 is engaged with the engagement pin 3, and is linked with the operation of the engagement pin 3. The latch 5 holds the engagement of the first arm 4 and the engagement pin 3. The latch spring 6 pre-tensions the latch 5 in a direction in which the engagement of the first arm 4 and the engagement pin 3 is held by the latch 5. The movable element 7 is installed to the first arm 4, and has a movable contact 7a. The fixed element 8 has a fixed contact 8a that contacts the movable contact 7a. The arc chamber 10 eliminates an arc 16 that is generated between the movable contact 7a and the fixed contact 8a when the movable contact 7a is separated from the fixed contact 8a. The arc rolling ring 11 moves the arc 16 toward the arc chamber 10. The electromagnet portion 13 drives an actuator 13g in the case where a short-circuit current flows in a circuit. The second arm 14 drives the latch 5 against the pre-tension of the latch 5 by the latch spring 6 in the case where the actuator 13g is driven, and releases the engagement of the engagement pin 3 and the first arm 4. Further, the second arm 14 rotates around the rotation shaft 15, and the distance L2 between the abutting position of the latch 5 and the rotation shaft 15 is longer than the distance Ll between the position pressed by the driving of the actuator 13g and the rotation shaft 15. Thus, in the circuit breaker 100, it is possible to further increase the separation speed and the separation distance of the contacts at the breaking operation, and it is possible to easily improve the current breaking performance in the circuit breaker 100.

[0057] Further, the second arm 14 is formed of an insulating member. Thus, in the circuit breaker 100, it is possible to further suppress the attachment of the arc gas or the molten matter or the like as compared with the case where the second arm 14 is formed of metal, while the presence of the second arm 14 to the position of the movable element 7 and the fixed element 8 is limited.

[0058] Further, the second arm 14 has an extension portion 14a and an abutting portion 14b. The middle portion of the extension portion 14a is rotatably supported to the rotation shaft 15. The abutting portion 14b is continuous to the extension portion 14a, and abuts against the latch 5. The abutting portion 14b opposes the movable contact 7a and the fixed contact 8a. Thus, in the circuit breaker 100, it is possible to suppress the case where the arc gas or the molten matter or the like generated at the breaking operation flies to and attaches to the internal mechanism such as the first arm 4 and the latch 5, and it is possible to suppress the reduction of the performance after the breaking of the short-circuit current in the circuit breaker 100.

[0059] Further, the opposing surface 14d of the abutting portion 14b to the movable contact 7a and the fixed contact 8a is formed in a concave shape. Thus, in the circuit breaker 100, it is possible to more effectively suppress the flying of the arc gas or the molten matter or the like to the internal mechanism.

[0060] Further, the length of the abutment portion 14b in the extension direction of the rotation shaft 15 is longer than the movable contact 7a and the fixed contact 8a. Thereby, in the circuit breaker 100, the flying of the arc gas or the molten matter and the like to the internal mechanism can be more effectively suppressed.

[0061] Further, the length of the abutment portion 14b in the extension direction of the rotation shaft 15 is longer than the movable contact 7a and the fixed contact 8a. Thereby, in the circuit breaker 100, the flying of the arc gas or the molten matter and the like to the internal mechanism can be more effectively suppressed.

[0062] The structure shown in the above embodiments shows one example, and can be combined with other known technologies, and a part of the structure can be omitted or changed without departing from the gist of the present application.

[0063] Explanation of Reference Numerals

[0064] 1 frame, 1a opening, 2 handle, 2a operation portion, 2b, 15 rotation shaft, 2c rotation portion, 2d protruding portion, 3 engagement pin, 4 first arm, 5 latch, 5a holding portion, 5b, 14b abutment portion, 6 latch spring, 7 movable member, 7a movable contact, 8 fixed member, 8a fixed contact, 9 main spring, 10 arc chamber, 11 arc rolling ring, 12 overload detection device, 13 electromagnet portion, 13a coil, 13b, 13c yoke portion, 13d tube, 13e fixed core, 13f movable core, 13g actuator, 13h hook, 13h1 first extension portion, 13h2 second extension portion, 14 second arm, 14a extension portion, 14b1 abutment surface, 14b2 cutout portion, 14c concave space, 14d opposite surface, 16 arc, 100 circuit breaker.

Claims

1. A circuit breaker, characterized in that: have: a handle, which is operated by a user; a locking pin rotatably mounted on the handle; a first arm engaged with the engaging pin and linked to the movement of the engaging pin; a latch for maintaining engagement between the first arm and the engagement pin; a latch spring for pre-tightening the latch in a direction in which the latch maintains engagement between the first arm and the engagement pin; a movable member mounted on the first arm and having a movable contact; a fixed member having a fixed contact in contact with the movable contact; an arc extinguishing chamber that extinguishes an arc generated between the movable contact and the fixed contact when the movable contact is separated from the fixed contact; an arc runner, which moves the arc toward the arc extinguishing chamber; an electromagnet portion that drives the actuator when a short-circuit current flows through the circuit; and a second arm that drives the latch against the preload force of the latch generated by the latch spring when the actuator is driven, thereby releasing the engagement between the engagement pin and the first arm; The second arm has: an extension portion, a middle portion of which is rotatably supported on the rotation shaft; as well as an abutment portion, which is continuous with the extension portion and abuts against the latch, The contact portion faces the movable contact and the fixed contact, The second arm rotates about the rotation axis, and a distance between a position of contact with the latch and the rotation axis is longer than a distance between a position pressed by driving of the actuator and the rotation axis.

2. The circuit breaker according to claim 1, wherein: The second arm is formed of an insulating member.

3. The circuit breaker according to claim 1, wherein: The contact portion has a concave surface formed on a surface facing the movable contact and the fixed contact.

4. The circuit breaker according to claim 1, wherein: The length of the contact portion in the extending direction of the rotation shaft is longer than the lengths of the movable contact and the fixed contact in the extending direction of the rotation shaft.

5. The circuit breaker according to any one of claims 1 to 4, characterized in that The length of the contact portion in the extending direction of the rotation shaft is 0.9 times or more the length of the rotation shaft in the extending direction inside the circuit breaker.

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