WO1997035333A1

WO1997035333A1 - Circuit breaker

Info

Publication number: WO1997035333A1
Application number: PCT/JP1996/000670
Authority: WO
Inventors: Haruhisa Toda; Kohei Kurata; Sinsaku Yamasaki
Original assignee: Mitsubishi Denki Kabushiki Kaisha
Priority date: 1996-03-15
Filing date: 1996-03-15
Publication date: 1997-09-25
Also published as: TW353756B; EP0827173B1; KR19990008310A; JP3814671B2; EP0827173A1; DE69636639D1; DE69636639T2; KR100336946B1; EP0827173A4

Abstract

A circuit breaker having a small-sized handle arm (59), wherein a handle (62) is prevented from moving to the open circuit position when a movable contact (44a) and a stationary contact (43a) are fused. A toggle link mechanism (58) includes a link (54) opposed to the handle, and the link (54) is provided with a cam (54a). When the handle (62) is moved to the open circuit position at the time of fusing of the contacts, the cam (54a) is engaged with a bent portion (59a) of the handle arm (59) and prevents the movement of the handle (62) to the open circuit position.

Description

Description Circuit breaker Technical field

The present invention relates to a circuit breaker in which a handle is prevented from moving to an open circuit position when a movable contact and a fixed contact of the circuit breaker are welded. Background art

FIG. 11 is a cross-sectional view showing a conventional circuit breaker disclosed in, for example, Japanese Utility Model Publication No. 1-242286. In the figure, 1 is a cover, 2 is a base, and both are made of synthetic resin. Reference numeral 3 denotes a housing composed of the cover 1 and the base 2, and reference numeral 4 denotes a fixed contact fixed to the base 2, which has a terminal portion 5 at one end so that an external conductor (not shown) can be connected thereto. A fixed contact 6 is provided on the upper surface of the end. 7 is a movable contact having a movable contact 8 opposed to the fixed contact 6, 9 is a movable contact arm for rotatably supporting the movable contact 7 by a pivot pin 10 and 11 is a movable contact A contact pressure spring that is interposed between the child arm 9 and the movable contact 7 and constantly urges the movable contact 7 in the direction of the fixed contact 6, 12 is a movable contact arranged in parallel with all poles This is a crossbar made of an insulator connecting one end of the child arm 9. An arc extinguishing device 13 extinguishes the arc generated between the contacts 6 and 8. A plurality of arc extinguishing magnetic plates 15 are arranged inside a pair of arc extinguishing side plates 14. 16 is a lower link pivotally supported at one end by a movable contact arm 9 on a shaft 17, and 18 is a shaft 2 at one end at the other end of the lower link 16 and the other end at a cradle 19. The upper link is rotatably supported by 0 and 21. 2 2 is the lower link A toggle link mechanism comprising an upper link 18, an upper link 18 and an axis 20, and the axis 20 is an elbow. Reference numeral 23 denotes a handle arm whose one end (not shown) is rotatably supported at a predetermined position with respect to the toggle link mechanism 22. Reference numeral 24 denotes one end of the handlebar through a spring hook pin 25. A toggle spring with the other end stretched around the shaft 20 at the other end of the cover 23, and a handle 26 that can be operated from outside the cover 1 and is made of synthetic resin, interlocked with the handle arm 23 I do. 2 7 is a pie metal connected to the movable contact 7, 2 8 is a fixed iron core fixed to the pie metal 2 7, 2 9 is a movable iron core arranged to face the fixed iron core 28, 30 is A rotatable trip bar 31 to which the movable iron core 29 is fixed is a rotatable latch, one of which is always locked to the cradle 19 and the other of which is always locked to the tripper 30. Reference numeral 2 denotes a cradle shaft that rotatably supports the cradle 19, and 33 denotes a stopper that locks the cradle 19 during tripping, and is engaged with and fixed to the frame 34. The frame 34 also supports a fulcrum for positioning the cradle shaft 32 and rotating the latch 31 described above.

Next, the operation will be described. In Fig. 12 where the contacts are open, the handle 26 can be moved to the closed position (tilt right) with the cradle 19 locked by the latch 31 and the toggle link fence 2 2 is extended, and the movable contact 8 is brought into contact with the fixed contact 6, and the closed state shown in FIG. 11 is established. Next, when the handle 26 is tilted to the road position (to the left), the toggle link mechanism 22 is bent, and the movable contact 8 is separated from the fixed contact 6, resulting in the open state shown in FIG. On the other hand, if an overcurrent flows in the circuit in the closed state shown in FIG. 11, the noy metal 27 or the movable iron core 29 operates and the engagement between the cradle 19 and the latch 31 is released. The cradle 19 is rotated clockwise about the cradle shaft 32 (see FIG. 13). Therefore, the connection point between the cradle 19 and the upper link 18, that is, the point of the shaft 21, forms the action line of the toggle spring 24. As a result, the toggle link mechanism 22 is bent by the spring force of the toggle spring 24, and the movable contacts 8 are separated from the fixed contacts 6 for all the poles by the crossbar 12 in conjunction with each pole. Thus, the trip state shown in FIG. 13 is obtained.

In the circuit breaker as described above, if the movable contact 7 is welded in a closed state due to an abnormal current and cannot be separated by any chance, as shown in FIG. If the handle 26 is moved to the closed side, it is possible to extend the toggle spring 24 more than normal and stop the movement of the handle 26 to the open position. The closed position of the contact 7 does not match.

As a conventional example, there is a circuit breaker disclosed in Japanese Patent Publication No. Hei 11-1991 / 76, which uses an open / close lever (corresponding to a handle arm) and a movable contact device when welding is performed between the contacts. Are engaged so that the handle cannot move to the open position.

In the conventional circuit breaker as described above, when the movable contact is welded in a closed state due to an abnormal current, the handle can be prevented from moving to the open position, but the handle arm is moved to the movable contact device. There is a problem that the handle arm is enlarged because it is directly engaged with the steering wheel. SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and when a movable contact and a fixed contact are welded, the handle cannot be moved to an open circuit position, and the handle arm has a relatively small size. It is intended to be compact.

It is another object of the present invention to prevent the handle from moving to the open position when the movable contact and the fixed contact are welded, to make the handle arm relatively small, and to have a strong mechanism. Disclosure of the invention

In the circuit breaker according to the present invention, a fixed contact, a movable contact opposed to and separated from the fixed contact inside the insulated housing composed of the base and the cover, and driving the movable contact A toggle link mechanism, a handle arm rotatably supported at a predetermined position relative to the toggle link mechanism, and a trip device for operating the toggle link mechanism in response to an overcurrent are housed. In the circuit breaker, the toggle link mechanism is provided with a blocking portion that engages with the handle arm when the fixed contact and the movable contact are welded to prevent the handle from moving to the open position. As a result, the handle can be prevented from moving to the open position, and the handle arm can be formed relatively small.

The blocking portion is provided on the handle side link of the toggle link mechanism, and is a force portion that engages with the handle arm when the fixed contact and the movable contact are welded to prevent the handle from moving to the open position. . This makes it possible to prevent the handle from moving in the direction of the open position, and to make the handle arm relatively small.

Further, the blocking portion that engages with the handle arm of the handle-side link of the toggle link mechanism is formed by an arc-shaped cam portion centered on the fulcrum of the handle-side link. By aligning the fulcrum of the handle side link with the center of the cam section, the handle side link rotates, but the handle does not move further in the direction of the open circuit position than the engagement position with the cam section, so the indication of contact welding is displayed. Becomes clear.

Further, in the process of moving the handle in the opening direction when the fixed contact and the movable contact are welded to each other, the cam portion engaged with the handle arm of the handle side link is engaged with the handle arm in the first half of this movement process. A cam portion and a first cam portion that engages the handle arm later in the movement process. It has been achieved. Thus, in the process of moving the handle in the counterclockwise direction from the closed state to the open state of the circuit breaker, the bending engagement portion of the handle arm engages with the second cam portion of the handle side link, Since the connecting portion between the handle side link and the movable contact side link is bent quickly, the operation of the route is more reliable. When the welding state of the contacts is small, the movable contact is pulled up by the moment acting in the clockwise direction to open the contacts. Further, by moving and engaging the first cam portion, the handle is prevented from further moving in the open circuit position direction I.

Also, the cam portion that engages with the handle arm of the handle-side link is formed by the first arc-shaped cam portion centered on the fulcrum of the handle link, and the movable contact side link side from the fulcrum of the handle side link. It is formed by an arc-shaped second force part having a center. As a result, in the process of moving the handle in the counterclockwise direction from the closed state to the open state of the circuit breaker, the bending engagement portion of the handle arm engages with the second cam portion of the handle side link, Since the connecting portion between the handle side link and the movable contact side link is quickly bent, the opening operation is more reliable. When the welding state of the contacts is small, there is an effect that the movable contact is pulled up by the moment working clockwise to separate the contacts. Further, by moving and engaging with the first cam portion, the handle is prevented from further moving in the direction of the open circuit position.

A fixed contact inside an insulating housing composed of a base and a cover, a movable contact facing and separating from the fixed contact, a crossbar connecting one end of the movable contact, and a movable contact. , A handle arm rotatably supported at a predetermined position relative to the toggle link mechanism, a handle linked to the handle arm, and a toggle link in response to overcurrent. In a circuit breaker equipped with a trip device that activates the mechanism, a fixed contact between the crosspar and the handle arm When the fixed contact and the movable contact of the movable contact are welded to each other, they are engaged with each other between the crossbar and the handle arm to prevent the handle from moving to the open position. As a result, the handle can be prevented from moving in the direction of the open position, and the handle arm can be formed relatively small, and the stop can be applied to the strong crossbar, so that a somewhat excessive force is applied. Is strong without breaking even if it works o

Furthermore, a twist spring is provided for constantly engaging the collar with the handle arm. As a result, by constantly urging the handle arm clockwise, the movement of the handle in the closing direction is ensured, and the position of the contact point of the circuit breaker and the display state of the handle are reliably linked. is there. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a side sectional view showing a circuit breaker according to Embodiment 1 of the present invention, showing a closed state.

FIG. 2 is a cross-sectional view of a main part when the circuit breaker of FIG. 1 is in an open circuit state.

FIG. 3 is a side sectional view showing a main part when the circuit breaker of FIG. 1 is in a trip state.

FIG. 4 is a side sectional view showing a state in which the handle is moved in the direction of the open circuit position in a state where the contacts of the circuit breaker in FIG. 1 are welded.

FIG. 5 is a side sectional view showing a circuit breaker according to Embodiment 2 of the present invention.

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FIG. 6 is an enlarged side sectional view showing a state where the handle is moved in the direction of the open circuit position in a state where the contacts of the circuit breaker in FIG. 5 are welded. FIG. 7 is an enlarged side sectional view showing a state where the toggle link structure has moved from the state of FIG.

FIG. 8 is a side sectional view showing a circuit breaker according to Embodiment 3 of the present invention, showing a closed state.

FIG. 9 is a side cross-sectional view showing a state where the handle has been moved toward the open circuit position in a state where the contacts of the circuit breaker in FIG. 8 are welded.

FIG. 10 is a side sectional view showing a circuit breaker according to Embodiment 4 of the present invention.

FIG. 11 (1) is a side sectional view showing a conventional circuit breaker, showing a closed state.

FIG. 12 is a side sectional view showing a conventional circuit breaker, showing an open circuit state.

FIG. 13 is a side sectional view showing a conventional circuit breaker, showing a trip state.

FIG. 14 is a side sectional view showing a conventional circuit breaker, showing a state in which the contacts are welded and the handle is moved to the open position. BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 is a side sectional view showing a circuit breaker according to Embodiment 1 of the present invention with a part cut away to show the inside thereof, showing a closed state. FIG. 2 is a cross-sectional view of a main part when the circuit breaker of FIG. 1 is in an open circuit state, and FIG. 3 is a cross-sectional view of a main part when the circuit breaker of FIG. 1 is in a trip state. FIG. In the figure, 40 is a cover, 41 is a base, and both are made of synthetic resin. Reference numeral 42 denotes a housing composed of the cover 40 and the base 41, and reference numeral 43 denotes a fixed contact fixed to the base 41, which has a fixed contact 43a. 4 4 is a movable contact having a movable contact 4 4 a opposed to the fixed contact 4 3 a And is rotatably supported by pivot pins 45. Reference numeral 46 denotes a crossbar made of an insulator connecting one end of each of the movable contacts 44 arranged side by side on all poles. A contact pressure spring 47 is interposed between the movable contact 44 and the cross bar 46 and constantly urges the movable contact 44 in the direction of the fixed contact 43a. Reference numeral 48 denotes a flexible conductor, one end of which is connected to the movable contact 44 and the other end of which is connected to a trip device (not shown). An arc extinguishing device 49 extinguishes an arc generated between the two contacts 43a and 44a. A plurality of magnetic extinguishing magnetic plates 51 are arranged inside a pair of arc extinguishing side plates 50. I have.

52 is a movable contact side link (hereinafter referred to as a lower link) rotatably supported at one end by a shaft 53 on a cross bar 46, and 54 is one end connected to the other end of the lower link 52. The other end is a handle-side link (hereinafter referred to as an upper link) rotatably supported by cradles 55 by shafts 56 and 57, respectively. The upper link 54 is provided with a blocking portion. ing. Specifically, the blocking portion is formed of a half g R arc-shaped cam portion 54 a centered on the center point of the shaft 57 serving as a fulcrum of the upper link 54. Reference numeral 58 denotes a toggle link mechanism including a lower link 52, an upper link 54, and a shaft 56, and the shaft 56 serving as an elbow. Reference numeral 59 denotes a handle arm, which has a bending engagement portion 59a, is rotatable to a predetermined relation position with respect to the toggle link mechanism 58, and one end 59b serves as a rotation fulcrum, and a frame (not shown) It is pivoted to. Reference numeral 60 denotes a toggle spring having one end suspended on the handle arm 59 via the spring retaining pin 61 and the other end suspended on the shaft 56, respectively. Reference numeral 62 denotes a handle which can be operated from the outside of the force par 40 and is made of synthetic resin, and is interlocked with the handle arm 59. Reference numeral 63 denotes a latch, which has a latch engaging portion 63 a that engages with the cradle 55, a recess 63 b into which the latch support shaft 64 fits, and a bow I removal device (not shown). Engage and rotate about the latch support shaft 64. 6 5 is a cradle support shaft pivotally supported by a frame (not shown), 6 Reference numeral 6 denotes a storage tube for the upper link 54 and the movable contact 44.

Next, the operation will be described. In FIG. 2 where the contacts are open, if the cradle 55 is engaged with the latch 63 and the handle 62 is moved to the closed position (rightward tilt), the toggle link mechanism 58 will be activated. The movable contact point 44a is extended and comes into contact with the fixed contact point 43a, and the closed state shown in FIG. 1 is obtained. Next, if the handle 62 is tilted to the open position (to the left), the toggle link mechanism 58 is bent when the axis of the toggle spring 60 exceeds the action line (dead point) connecting the axis 56 and the axis 57. Then, the lower link 52 is lifted, and the movable contact 44a is separated from the fixed contact 43a, and the open state shown in FIG. 2 is established. On the other hand, if an overcurrent flows in the circuit in the closed state shown in FIG. 1, the bow I remover (not shown) operates and the engagement between the cradle 55 and the latch 63 is released (see FIG. 1). The cradle 55 is rotated clockwise about the cradle support shaft 65 (see FIG. 3). Therefore, since the connecting point of the cradle 55 and the upper P link 54, that is, the point of the shaft 57 exceeds the action line of the toggle spring 60, the toggle link mechanism 58 is bent by the spring force of the toggle spring 60. As a result, the movable contact 44a is disengaged from the fixed contact 43a for all the poles in conjunction with each pole by the crosspar 46, and the trip state shown in FIG. 3 is established. Fig. 4 shows a state in which, for example, a large pulsed current flows in a closed state and the engagement between the cradle 55 and the latch 63 is not released, and between the fixed contact 43a and the movable contact 44a. This shows the case where the welding phenomenon occurs and the movable contact 44a does not separate. In this state, the toggle link mechanism 58 is held at the closed position, and as shown in FIG. 4, the handle 62 is turned counterclockwise to the open side in order to open the circuit due to the necessity of maintenance and inspection. , The toggle spring 60 is extended, and the handle arm 59 is also rotated counterclockwise to move in the open circuit direction. However, while the handle 62 is moving in the counterclockwise direction, the bending engagement portion 59 a of the handle arm 59 is maintained in the closed state. It collides with and engages with the cam portion 54a of the upper link 54 of the toggle link mechanism 58, which prevents the handle arm 59 from further moving toward the open circuit position.

Note that the bending engagement portion 59a of the handle arm 59 may collide with and engage with the lower link of the toggle link mechanism 58 maintained in a closed state. As described above, the blocking portion, specifically, the cam 54a and the bending engagement portion 59a of the handle arm 59 are collided and engaged with the toggle link mechanism 58, so that the movable contact is made as in the conventional case. The handle arm becomes smaller than the slave device and the handle arm colliding and engaging.

FIG. 5 is a side sectional view showing a circuit breaker according to a second embodiment of the present invention with a part cut away to show the inside thereof. In a state where the contacts of the circuit breaker are welded, the handle is moved in the direction of the open circuit position. Shows the state of movement. FIG. 6 is an enlarged side sectional view of a main part showing a state where the handle is moved in the direction of the open circuit position * in a state where the contacts of the circuit breaker of FIG. 5 are welded. In the figure, reference numeral 100 denotes an upper link, and the shape of a cam portion which engages with the bending engagement portion 59 a of the handle arm 59 is a half-centered shape about the center point C 1 of the shaft 57. An arbitrary position separated from the center point C1 of the first cam portion 100a formed and the center point C1 of the shaft 57 by the dimension L to the lower link 52 side is set as a center point C2, and half of the center point C2. The second cam portion 100 b formed with the diameter R 2 is formed. For example, when applied to a circuit breaker with a 40 OA (ampere) frame, the position of the center point C2 is in the range of L = 2.5 to 3 mm, the center point C1 and the axis 56 It is set at a position rotated clockwise by about 0 degrees with respect to the dashed line connecting the center point C3.

In the state shown in Fig. 5, for example, when a large pulse-like current flows in a closed state and the engagement between the cradle 55 and the latch 63 is not released, the fixed contact 43a and the movable contact 44a are And the movable contact 4 4 a is released. Indicates no case. In this state, as shown in the detailed enlarged side sectional view of the main part in FIG. 6, when the handle 62 is moved counterclockwise to the related road side to open the circuit due to the necessity of maintenance and the like, the toggle spring When 60 is extended, the handle arm 59 is also rotated counterclockwise, and is moved in the direction of the open circuit position. However, during the movement of the handle in the counterclockwise direction, that is, in the first half of the process of moving the handle 62 in the opening direction, the bending engagement portion 59 a of the handle arm 59 becomes the second link of the upper link 100. Engage with cam portion 100b. At this time, a pressing force F2 acts on the contact の between the second cam portion 100b and the bending engagement portion 59a of the handle arm 59 toward the center point C2. Since the direction of F 2 acts in the direction of the center point C 2, a clockwise moment M 2 F 2 XL acts on the upper link 100 with the center point C 1 of the axis 57 as a fulcrum. Rotate the shaft 56 connecting the upper link 100 and the lower link 52 in the direction of arrow D, pull up the lower link 52 in the direction of arrow E as shown in Fig. 7, and fix the movable contact 4 4 Attempts to separate from contact 43, but moves and stops by gap G (see Fig. 6) due to welded contacts. When the shaft 56 is bent, the bent engagement portion 59a of the handle arm 59 moves to a position where it is engaged with the first cam portion 100a. Later in the process of moving 2 in the opening direction, the pressing force F 1 acts toward the center point C 1 at the point of contact with the first cam portion 100 a, so the handle arm 59 is further pushed. It prevents movement in the direction of the road. According to the second embodiment, in the process of moving the handle 62 counterclockwise from the closed state to the open state of the circuit breaker, the bending engagement portion 59 a of the handle arm 59 is connected to the upper link 1. The second opening 110 engages with the second cam portion 100 to bend the connecting portion between the upper link 100 and the lower link 52 quickly, so that the opening operation is more reliable. When the welding state of the contacts is small, the movable contact 4 4 is set by the clockwise moment M = F 2 XL. It has the effect of lifting and opening the contacts. Further, the upper link 100 is rotated in the bending direction, and the first cam portion 100a is engaged with the bent engagement portion 59a of the handle arm 59, whereby the upper link 100 is rotated. Rotates until the movable contact 44 is pulled up, but the handle 62 prevents movement from the position engaged with the cam portion 100a toward the open circuit position.

FIG. 8 is a side sectional view showing a circuit breaker according to Embodiment 3 of the present invention with a part cut away to show the inside thereof, showing a closed state. In the figure, 1 to 66 are the same as those in the first embodiment, and the description is omitted. Reference numeral 70 denotes a stopper, which is rotatably supported by a stud support shaft 65 of a cradle 55, an arm portion 70a is formed at one end, and a bending arm of a handle arm 59 is formed at the other end. A stop shaft 71 engaging with the joint portion 59a is fixed.

FIG. 9 shows a state in which, for example, a large pulsed current flows in a closed state, and the engagement between the cradle 55 and the latch 63 is not released, and between the fixed contact 43a and the movable contact 44a. This shows the case where the welding phenomenon occurs and the movable contact 44a does not separate. In the contact-welded state, when the handle 62 is moved counterclockwise from the state shown in Fig. 8 to the open side to open the circuit due to the necessity of maintenance, etc., the toggle spring 60 is extended and the handle arm 5 is extended. 9 is also rotated counterclockwise and moved toward the open position (see Fig. 9). However, while the handle 62 is moving in the counterclockwise direction, the shaft 71, which is in contact with the bending engagement portion 59a of the handle arm 59, is rotated in the counterclockwise direction. The arm 70a of the tongue 70 rotates counterclockwise to collide with and engage with the projection 46a of the strong crossbar 46 as a structure, and as shown in FIG. 5 to prevent further movement toward the open position. The handle arm becomes smaller than the conventional case where the movable contact device and the handle arm collide and engage with each other.

FIG. 10 is a side view of a circuit breaker showing Embodiment 4 of the present invention, In the figure, reference numeral 72 denotes a torsion spring, which engages with the stopper shaft 71 so as to always contact the stopper shaft 71 with the bending engagement portion 59a of the handle arm 59, and the stopper spring 70 Is constantly biased clockwise.

According to the fourth embodiment, the urging force of the torsion spring 72 against the stop 70 is the clockwise urging force of the handle arm 59 and the handle 62.

Claims

The scope of the claims

1. A fixed contact (43) inside an insulated housing (42) consisting of a base (41) and a cover (40), and a movable contact (44) that faces and separates from the fixed contact (43). A toggle link mechanism (58) for driving the movable contact (44); and a handle arm (59) rotatably supported at a predetermined position relative to the toggle link mechanism (58). In a circuit breaker equipped with a handle (62) interlocking with the handle arm (59) and a tripping device that operates the toggle link mechanism (58) in response to an overcurrent, the toggle link mechanism ( 58), the fixed contact (43a) of the fixed contact (43) and the movable contact (44a) of the movable contact (44) are welded to the handle arm (59) when they are welded. A blocking portion (54a) for blocking the handle (62) from moving to the open position is provided. A circuit breaker characterized by the above.

2. The blocking part (54a) is provided on the handle side link (54) of the toggle link mechanism (58), and the fixed contact (43a) of the fixed contact (43) and the movable contact (44) The circuit breaker according to claim 1, wherein the movable contact (44a) is a cam portion (54a) that engages with the handle arm (59) when welding to prevent the handle (62) from moving to the open position. vessel.

3. The blocking part (54a) that engages with the handle arm (59) of the handle side link (54) of the toggle link mechanism (58) is replaced with an arc-shaped cam centered on the fulcrum of the handle side link (54). 3. The circuit breaker according to claim 1, wherein the circuit breaker is formed by a part (54a).

4. When the fixed contact (43a) and the movable contact (44a) are welded together, the handle (62) is disengaged with the force (54a) that engages the handlearm (59) of the handle-side link (54). In the process of moving in the opening direction, this moving process A second cam portion (100b) that engages the handle arm (59) in the first half of the process, and a first cam portion (100a) that engages the handle arm (59) in the second half of the movement process. 3. The circuit breaker according to claim 2, wherein the circuit breaker is formed by:

5. The force (54a) that engages with the handle arm (59) of the handle-side link (54) is moved to the first arc-shaped first cam (100) centered on the fulcrum of the handle-side link (54). a) and an arc-shaped second cam portion (1 Ob b) centered on the movable contact side link (52) side from the fulcrum of the handle side link (54). Circuit breaker according to 4.

6. A fixed contact (43) inside an insulated housing (42) consisting of a base (41) and a cover (40), and a movable contact (44) that faces and separates from the fixed contact (43). And a cross link (46) connecting one end of the movable contact (44), a toggle link mechanism (58) for driving the movable contact (44), and a toggle link mechanism (58). A handle arm (59) rotatably supported at a predetermined relationship, a handle (62) interlocking with the handle arm (59), and the toggle link mechanism (58) in response to an overcurrent. And a fixed contact (43a) of the fixed contactor (43) and the movable member between the crosspar (46) and the handle arm (59). When the movable contact (43a) of the contact (44) is welded, the crossbar (46) and the upper Engage between each other and the handle arm (59), circuit breaker, characterized in that the handle (62) is provided Sutotsuba (70) for preventing the movement in the open position.

7. The circuit breaker according to claim 6, further comprising a twist spring (72) for constantly engaging the strike (70) with the handle arm (59).