KR100858590B1 - Circuit breaker - Google Patents

Abstract

Challenge : To improve the reliability of the breaking operation by increasing the contact opening force acting on the movable contact during the trip operation in the molten state of contact bonding.

Resolution

The opening / closing mechanism 6 of the circuit breaker has a handle lever 8 coupled to the operation handle 7, a latch 11 engaged with the latch support 10 by fastening one end to the support shaft 9, and a toggle pin 14. It consists of the upper link (12) and the lower link (13) coupled through each other, the toggle link pivoting the other end of each link to the latch (11), contact holder (4), the top of the toggle pin and the handle lever In the opening / closing spring 17 tightened in between, the main circuit contact is opened and closed by the ON / OFF operation of the handle, and the latch is released by the overcurrent detection so that the opening / closing mechanism is tripped. When the connecting shaft 11a provided in the latch is engaged with the U-shaped open bearing portion 12b formed at the upper end of the upper link, the pivoting connection is slidably connected, and the trip operation is performed while the fixed / movable contact is melted. Of the opening and closing spring 17 without being restrained by the upper link The ear spring force is applied directly to the toggle pin 14 to enhance the open force of the melt-attached contact.

Circuit breaker

Description

Circuit breaker {CIRCUIT BREAKER}

1 is a configuration diagram of a circuit breaker according to an embodiment of the present invention, (a) is an internal structure diagram of the entire circuit breaker, (b) is a top link of the latch and the toggle link of the opening and closing mechanism in (a) Perspective view showing the assembling structure of the

Figure 2 is an exploded perspective view of Figure 1 (b)

FIG. 3 is a side view illustrating an on operation state of the opening and closing mechanism in FIG. 1. FIG.

4 is a side view showing an off operation state of the opening and closing mechanism.

5 is a side view illustrating a trip operation state of the opening and closing mechanism.

6 is a side view showing a tripping operation state of the opening and closing mechanism in the state in which the contact is melted

7 is an explanatory view of the action of the opening and closing spring in the trip operation of FIG. 6;

FIG. 8 is a view showing an on state in a configuration diagram of a circuit breaker disclosed in Patent Document 1. FIG.

FIG. 9 is a side view illustrating an off operation state of the opening and closing mechanism in FIG. 8. FIG.

FIG. 10 is a side view illustrating a trip operation state of the opening and closing mechanism in FIG. 8. FIG.

FIG. 11 is a diagram illustrating a trip operation state in a melt-attached state of a contact in the circuit breaker of FIG. 8. FIG.

(Explanation of symbols for the main parts of the drawing)

2: fixed contactor

3: operation contactor

4: contact holder

6: opening and closing mechanism

6a: frame

7: operation handle

8: handle lever

8a: Stopper piece

9: axis of latch

11: latch

12: phase link of the toggle link

12a: convex cam

12b: open bearing part

13: Harlink

14: toggle pin

17: opening and closing spring

Technical field

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit breaker for a circuit breaker, an earth leakage breaker, and the like, and more particularly, to a structure of an open / close mechanism of a circuit breaker.

Prior art

In the circuit breaker described above, when the main circuit contact is in a state in which the fixed contact and the movable contact are melted together by abnormal pulse current or the like in a closed energized state, the overcurrent trip device operates normally. The latch of the opening / closing mechanism is released while the main circuit contact is closed, and the operation handle moves from the ON position to the TRIP display position and stops.

In this case, if the handle can be moved to the OFF position while the contact is melted, the main circuit contact of the circuit breaker may be mistaken, and if the maintenance or inspection of the load side circuit is performed in this state, the worker will be activated. There is a risk of electric shock due to contact with air.

Therefore, as a safety measure against the above problem, a circuit breaker having an isolation function of various methods for mechanically locking to prevent movement of the handle to the OFF position when the contact is melted while energized has been proposed in the past, As an example, the opening and closing mechanism is provided with a stopper mechanism that prevents the handle from moving to the OFF position in the molten state of contact, and additionally is equipped with a opening member in the opening and closing mechanism. ), The circuit breaker releases the latch by the handle operation, forcibly trips the opening and closing mechanism, and uses the spring force of the opening / closing spring to release due to this tripping operation to remove the melted attachment between the contacts. It is known (refer patent document 1).

Next, the structure of the circuit breaker disclosed by patent document 1, and its operation state are shown in FIGS. 8-11. In each figure, reference numeral 1 denotes a main body case of a circuit breaker, 2 a fixed contact of a main circuit, 2a a fixed contact, 3 a movable contact supported by a rotary contact holder 4, 3a a movable contact, and 5 SOHO grid, 6 is an opening / closing mechanism connected to the contact holder 4, 7 is an operating handle, and a thermal type for detecting an overcurrent of the main circuit in case 1 (not shown) and giving a trip command to the opening / closing mechanism 6. An electronic overcurrent trip device is provided.

Here, the opening / closing mechanism 6 pivots the front end (lower side of illustration) to the frame 6a as shown in FIG. 9, and the handle lever 8 which coupled the upper end to the operation handle 7 is shown. ), A swing lever latch (11), an upper link (12), which pivots one end to the support shaft (9) and engages the pawl portion of the other end with the latch receiver (10). After the lower link 13 is engaged by the toggle pin 14, the other ends of the upper link 12 and the lower link 13 are latched 11 and the contactor by the pins 15 and 16, respectively. It is an assembly of a toggle link pivoted to the holder 4 and an opening / closing spring (tension spring) 17 which is tightly hung between the toggle pin 14 and the top of the handle lever 8. In addition, 18 is a trip crossbar connected to the latch support 10, 19 is a contact spring which presses the contact 3a of the movable contact 3 to the contact 2a of the stationary contact 2 at the closed pole position. to be.

Further, as a stopper means corresponding to the above-described isolation function, a convex cam 12a is formed on the side edge of the upper link 12, and the handle lever 8 is opposed to the convex cam 12a. On the ON side (left side of the figure) is provided with a stopper piece 8a in which the tip is bent into a ">" shape. In addition, as the above-mentioned opening member, the opening / closing mechanism 6 is moistened with a toggle pin 14 at one end, and the tip is replaced with a stopper piece 8a of the trip crossbar 18 and the handle lever 8. The Y-shaped ridge plate 20 is provided, and the ridge plate 20 is spring-loaded counterclockwise with a torsion coil spring provided on the axis of the toggle pin.

The opening and closing and tripping operation of the circuit breaker having the above-described configuration is described in detail in Patent Document 1, and in the closing state (see FIG. 8) in which the operation handle 7 is inclined to the ON position, the opening / closing spring 17 The upper link 12 (upper axis 15 of the upper side becomes a fixed point) and the lower link 13 of the toggle link which are subjected to the throwing force are stretched almost linearly, and the contact holder 4 is pressed in the counterclockwise direction. The contact 3a of the movable contact 3 abuts on the contact 2a of the fixed contact 2, and the main circuit contact is closed. In this state, when the operation handle 7 is tilted to the OFF position (see Fig. 9), the spring force action line of the opening / closing spring 17 reverses beyond the dead point (the support shaft 15 of the upper link 12), In this way, the upper link 12 and the lower link 13 of the toggle link mechanism are bent in a " > " shape so that the contact holder 4 rotates clockwise, and the movable contact 3 is opened from the fixed contact 2. Move, and the main circuit contact opens.

In addition, Fig. 10 shows a state in which the main circuit contact is opened by the trip operation. When the overcurrent flowing through the main circuit is detected in the ON state of Fig. 8 and the overcurrent trip device (not shown) is operated, the mechanical The output hits the trip crossbar 18 so that the latch receiver 10 releases engagement with the latch 11. Thereby, the latch 11 rotates the support shaft 9 counterclockwise to the point by the spring force of the opening / closing spring 17, and follows the upper link 12 connected to the latch 11 by following it. The support pin 15 is displaced to the position of FIG. As a result, the lower link 13 connected through the upper link 12 and the toggle pin 14 is pulled upward, and the contact holder 4 rotates clockwise to open the movable contact 3. . In addition, in this trip operation state, the operation handle 7 stops at the trip display position (middle between the ON position and the OFF position) shown in the figure, and also supports the upper end shaft 15 of the upper link 12 connected to the latch 11. ) Moves to the position shown. To re-insert the circuit breaker from this tripping operation state, the operation handle 7 is tilted from the TRIP position to the OFF position (see FIG. 9) to reset the latch 11, and then back to the ON position (see FIG. 8). Tip

On the other hand, when the handle 7 is moved from the ON position to the OFF position to turn OFF the circuit breaker in the state where the main circuit contact is melted, the handle lever (in the middle of the movement of the handle 7 as shown in FIG. 11). The stopper piece 8a of 8) presses the carry plate 20. As shown in FIG. Therefore, the garry plate 20 tilts clockwise with the toggle pin 14 as the point, and the front end of the plate presses the latch receiver 10 to release the engagement of the latch 11. Thereby, by the spring force (tension spring force) of the opening / closing spring 17 which was interposed between the handle lever 8 and the toggle pin 14, the latch 11 is set as a point in the counterclockwise direction. The rotating force acts, and in connection with this, the contact force F is applied to the contact holder 4 through the harlink 13. Since the opening force F acts in the direction of detaching the movable contact 3 from the fixed contact 2, if the melt adhesion of the contact is hardness, the melt adhesion is released and the movable contact 3 is opened, and FIG. 10. The operation shifts to the trip operation state.

In addition, when the fusion | melting adhesion state of a contact is serious, and fusion | melting adhesion is not peeled off even by the said handle operation, as shown in FIG. Engages with 12a, and prevents the operation handle 7 from moving from the position shown to the OFF position (isolation function).

Patent Document 1: Japanese Patent Application Laid-Open No. 2000-323003 (pages 4 to 7, FIGS. 1 to 6)

By the way, the above-mentioned conventional opening / closing mechanism (patent document 1) has the same problem as the following description in the open force, the number of parts, and the assembly surface which remove the melt-attached contact.

That is, the peel plate 20 for releasing the latch of the opening / closing mechanism in the middle of the movement of the handle 7 in peeling off the melt-bonded state by the handle operation in the melt-attached state of the contact is shown. Since the force spring (torsion coil spring) of this gari plate 20 is required, the number of parts of an opening-closing mechanism and the number of assembly processes are increased, and a product becomes expensive.

Further, in the melt-attached state of the contact, the opening force acting on the movable contact is small in the operation when the latch of the opening / closing mechanism is released through the above-mentioned opening member by the handle operation, and the melt adhesion between the contacts can be peeled off. The thing is limited to the case of the melt adhesion state which is very hardness.

That is, as shown in FIG. 1L, in the state immediately after releasing the latch 11 via the ridge plate 20 by the movement operation to the OFF direction of the handle 7 in the melt-attached state of the contact, the toggle link Since the position of is hardly displaced from the closed pole state shown in Fig. 8, and the upper end of the upper link 12 is fixedly connected to the latch 11 via the support shaft 15, the latch 11 is the upper link. (12), it is restrained by the harlink 13, and it cannot freely rotate to a release position (refer FIG. 10).

For this reason, the opening force F which acts on the contactor 3 so that the fusion | melting adhesion of a contact may be peeled off by the spring force of the opening-closing spring 17 interposed between the handle lever 8 and the toggle pin 14. Becomes That is, in the state immediately after the release of the latch shown in FIG. 11, the rotational torque in the counterclockwise direction is applied to the upper link 12 with the support shaft 15 as a point by the spring force of the opening / closing spring 17. The rotary torque is transmitted to the contact holder 4 via the harlink 13 and acts as an opening force F of the movable contact 3.

However, as can be seen from the position of the toggle link in FIG. 11, the axis line connecting the support shaft 15 and the toggle pin 14 connecting the upper end of the upper link 12 to the latch 11 and opening / closing are opened and closed. The angle between the spring force action line of the spring 17 is a small acute angle. Therefore, when the spring force of the opening / closing spring 17 is divided into a vector component in the direction along the axis of the upper link 12 and a vector component (rotating torque) for rotating the upper link 12 counterclockwise, the opening / closing spring ( Most of the spring force of 17) becomes a vector component along the axis of the upper link 12, and the rotational torque acting on the upper link 12 becomes very small. That is, the efficiency of converting the spring force of the opening / closing spring 17 into the rotational torque of the upper link 12 is low. For this reason, the contact force F which raises the movable contact 3 against the melting adhesion of a contact is small, and melt | dissolution of a contact by the release operation of the latch 11 except the case where the melt adhesion state is very hardness. It becomes difficult to peel off adhesion.

Moreover, the contact opening operation described above functions only in a state in which the latch is artificially released by manual operation of the handle, and in the case where the latch is released by the trip operation by the overcurrent trip device in the energized state where melting contact of the contact occurs, The function is finally made by the forced opening operation by the handle after the operation, but even in this case, sufficient opening force cannot be obtained because the efficiency of converting the spring force of the opening / closing spring into the rotation torque of the uplink is low as described above.

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and an object thereof is to melt the contact by improving the structure of the pivoting connection portion between the top link and the latch of the toggle link without solving the above problem and adding a new component. The present invention provides a circuit breaker with an isolation function that enhances the open force acting on a movable contact during a trip operation in an attached state, thereby improving the reliability of the breaking operation.

In order to achieve the above object, according to the present invention, there is provided a circuit breaker equipped with a movable contact supported by a fixed contactor of a main circuit and a rotary contact holder, an opening / closing mechanism linked to a contact holder, an operation handle, and an overcurrent trip device. The opening / closing mechanism includes a handle lever which pivots the front end to the frame, and is coupled to the operation handle, a latch whose one end is held by the frame, and the front end pole part is engaged with the latch receiver and is supported in a locking position, and a toggle pin. It consists of the upper link and the lower link coupled through, the toggle link overlying the other end of the upper link, the lower link to the latch, contact holder, respectively, and the opening and closing fastened between the top of the toggle pin and the handle lever It consists of an assembly with a spring, and opens and closes the main circuit contact by operating the handle ON and 0FF. According to the release to a trip operation to an opening and closing mechanism,

During a trip operation in the state of melt adhesion of the contact between the fixed and movable contacts, the latch pivotably pivots between the latch and the top link of the toggle link so that the latch can be rotated to the release position without being restrained by the upper link. (Claim 1), specifically, the U-shaped open bearing part (claim 2) or the long hole bearing part (claim 3) is formed in the upper end of the upper link, The pivoting connection between the latch and the upper link is slidable by engaging the connecting shaft provided in the latch with the long hole.

Moreover, in the case where the movable contact does not open by the trip operation in the state in which the contact was melt-attached, the isolation mechanism which prevents a handle from moving to an OFF position by a manual handle operation is a convex cam at the side edge of an upper link. And a female stopper piece is provided on the ON side of the handle lever to face the convex cam (claim 4).

With the above-described configuration, the return spring force of the opening / closing spring effectively acts as the opening force of the movable contact during the trip operation in the melt-attached state of the contact.

That is, in the state in which the latch is released by the trip operation, the downlink of the toggle link linked to the movable contact through the contact holder is constrained to melt attachment of the contact and cannot move freely, but the upper link can swing freely around the toggle pin. Can be. Thereby, the rotational torque acts on the latch through the upper link by the spring force of the opening / closing spring (opening / closing spring is tightly sandwiched between the toggle pin and the handle lever) applied to the toggle pin, and the latch is released by receiving the rotational torque. Rotate towards the location. In this case, since the upper link is connected to the lower link through the toggle pin, it does not follow the movement of the latch, but the connecting shaft provided in the latch can freely slide the U-shaped groove or the long hole of the bearing portion formed at the upper end of the upper link. As a result, the latch and the uplink do not bind to each other. As a result, the return spring force of the opening / closing spring acts as an opening force for directly pulling up the harlink connected to the toggle pin to remove the melt adhesion between the contacts. That is, the return spring force of the opening / closing spring is not converted to the rotational torque of the upper link as in the conventional structure, and all the return spring forces effectively act as the opening force of the movable contact.

Therefore, even if the melt adhesion state between the fixed / movable contacts is somewhat severe, the melt contact can be released to open the movable contact and the reliability of the breaking operation is improved.

In addition to the above-described configuration, by forming a convex cam on the side edge of the upper link, and providing a female stopper piece on the ON side of the handle lever opposite to the convex cam, If the melting of the contact does not come off even if the contact force caused by the above-described tripping operation is serious, the stopper piece provided on the handle lever is moved to the convex cam of the upper link even when the operation handle is moved to the OFF position. It is possible to secure the isolation function by fusing and preventing further movement of the handle.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described based on the Example shown to FIG. 1 thru | or FIG. In addition, the same code | symbol is attached | subjected to the member corresponding to FIGS. 8-11 in the figure of the Example, The description is abbreviate | omitted.

First, FIG. 1A shows the overall structure of the circuit breaker, and FIG. 1B and FIG. 2 show the pivoting connection structure between the latch of the opening and closing mechanism and the phase link of the toggle link. That is, the opening and closing mechanism in the circuit breaker of the illustrated embodiment is basically the same as the structure of Patent Document 1 shown in Fig. 8, but is a mechanism for providing an isolation function. A concave cam 12a (see FIG. 1B) is formed at the side edge of the upper link 12 so that the stopper piece 8a bent in a '-shape is opposed to the stopper piece 8a.

In addition, in the embodiment shown with respect to the pivoting connection structure between the latch 11 and the upper link 12, as shown in FIG. 2, the connection shaft 11a is formed in the latch 11, and this connection shaft The upper end part of the upper link 12 is provided with a linear guide part opposite the 11a, and the open bearing part 12b notched in U shape along the axial direction of the link is formed, and the opening / closing mechanism 6 of The connecting shaft 11a of the latch is engaged with the open bearing 12b in the assembled position so as to be slidably pivoted between the latch 11 and the upper link 12. Further, the U-shaped groove of the bearing portion 12b is set to a groove depth at which the connecting shaft 11a does not deviate from the U-shaped groove even when the latch 11 is rotated to the release position as described later.

The on, off, and trip operations by the above-described configuration are similar to those of a conventional circuit breaker, and in the closing state in which the operation handle 7 is inclined to the ON position, as shown in FIG. The lower link 13 extends almost linearly to rotate the contact holder 4 counterclockwise, and the contact 3a of the movable contact 3 contacts the fixed contact 2 to close the main circuit contact. . In addition, when the operation handle 7 is inclined to the OFF position (refer to FIG. 4) from this closed state, the action line of the opening-closing spring 17 inverts beyond the dead point, and thereby the upper link 12 of the toggle link mechanism The lower link 13 is bent in a " " shape, the contact holder 4 rotates clockwise, the movable contact 3 moves upward from the fixed contact 2, and the main circuit contact opens.

In addition, when the overcurrent tripping device (not shown) is activated by detecting the overcurrent flowing to the main circuit in the input state of FIG. 3, the mechanical output hits the trip crossbar 18, and the latch receiver 10 latches the latch 11. To release. Thereby, by the return spring force of the opening-closing spring 17 placed between the handle lever 8 and the toggle pin 14 ', the latch 11 rotates counterclockwise to the point counterclockwise. With movement, the connecting shaft 11a provided in the latch 11 moves to the left of the action line of the opening-closing spring 17. As shown in FIG. As a result, the upper link 12 and the lower link 13 of the toggle link are bent in a " " shape under the return spring force of the opening / closing spring 17, and the contact holder 4 rotates clockwise in conjunction with this. To open the movable contact 3.

Next, the operation of opening and closing the melt-bonded contact by the trip operation in the state in which the main circuit contacts are melt-bonded will be described with reference to FIGS. 6 and 7. As shown in FIG. 6, the latch 11 is released when the trip operation is performed in the state where the contact of the fixed contact 2 and the contact of the movable contact 3 are melted and attached. By the way, in this latch release state, the lower link 13 of the toggle link, which is linked to the movable contact 3 via the contact holder 4, is constrained to melt attachment of the contact and cannot move freely. It is possible to swing around the toggle pin 14. Thereby, the counterclockwise rotational torque acts on the latch 11 through the upper link 12 by the return spring force of the opening / closing spring 17 applied to the toggle pin 14, and receives the rotational torque to receive the latch ( 11 rotates toward the release position (position in FIG. 4) with the support shaft 9 as a point.

In this case, since the connecting shaft 11a provided in the latch 11 is pivotably connected to the U-shaped groove of the open bearing part 12b formed in the upper end of the upper link 12 along the guide part, The latch 11 is rotated without being restrained by the upper link 12 using the support shaft 9 as a point, and following the rotation of the latch 11, the upper link 12 is shown in FIG. It swings around the toggle pin 14 counterclockwise. As a result, there is a clearance gap g between the connecting shaft 11a and the bearing portion 12b due to the difference between the rotational trace of the connecting shaft 11a and the rotational trace between the bearing portion 12b. do.

Therefore, the return spring force f of the opening / closing spring 17 pulls up the lower link 13 directly connected to the toggle pin 14 without being restricted by the upper link 12 and the latch 11. It acts as an opening force F for removing the melt adhesion between the fixed and movable contacts. That is, the return spring force of the opening / closing spring 17 is effectively converted as the opening force of the movable contact 3 without any spring force being converted into the rotational torque of the upper link 12 as in the conventional structure (see Fig. 11). Will work.

As a result, even if the molten adhesion state between the contacts is somewhat severe, the molten adhesion can be detached by the return spring force of the opening / closing spring 17 to open the movable contact 3 to improve the reliability of the breaking operation.

In addition, when the melt adhesion state between the contacts is serious and the movable contact 3 cannot be opened by the opening force F acting on the trip operation described above, the operation handle 7 is moved from this position to the OFF position. Even if it is going to do so, the stopper piece 8a provided in the handle lever 8 fits and engages with the convex cam 12a formed in the side edge of the upper link 12 in the middle of the movement, and the operation handle 7 above. It stops moving. Thereby, the isolation function of a circuit breaker can be ensured.

In addition, although the U-shaped open bearing part 12b was formed in the upper end of the upper link 12, and was slidably connected to the connecting shaft 11a of the latch 11, the U-shaped open type was shown. Instead of the bearing portion 12b, a long hole-shaped bearing portion in the link axial direction is formed at the upper end of the upper link 12, and the connecting shaft 11a of the latch 11 is inserted into the long hole and slides. It may be possible to connect pivoting. In this structure, the coupling shaft 11a is separated from the latch 11 in consideration of the assemblability of the opening / closing mechanism, and is fixed to the latch 11 while being engaged with the long hole of the upper link 12.

With the above-described configuration, the return spring force of the opening / closing spring effectively acts as the opening force of the movable contact during the trip operation in the melt-attached state of the contact.

That is, in the state in which the latch is released by the trip operation, the downlink of the toggle link linked to the movable contact through the contact holder is constrained to melt attachment of the contact and cannot move freely, but the upper link can swing freely around the toggle pin. Can be. Thereby, the rotational torque acts on the latch through the upper link by the spring force of the opening / closing spring (opening / closing spring is tightly sandwiched between the toggle pin and the handle lever) applied to the toggle pin, and the latch is released by receiving the rotational torque. Rotate towards the location. In this case, since the upper link is connected to the lower link through the toggle pin, it does not follow the movement of the latch, but the connecting shaft provided in the latch can freely slide the U-shaped groove or the long hole of the bearing portion formed at the upper end of the upper link. As a result, the latch and the uplink do not bind to each other. As a result, the return spring force of the opening / closing spring acts as an opening force for directly pulling up the harlink connected to the toggle pin to remove the melt adhesion between the contacts. That is, the return spring force of the opening / closing spring is not converted to the rotational torque of the upper link as in the conventional structure, and all the return spring forces effectively act as the opening force of the movable contact.

Thus, even if the melt adhesion state between the fixed / movable contacts is rather severe, the melt contact can be released to open the movable contact and the reliability of the breaking operation is improved.

In addition to the above-described configuration, by forming a convex cam on the side edge of the upper link, and providing a female stopper piece on the ON side of the handle lever opposite to the convex cam, If the melt adhesion of the contact does not come off even by the opening force caused by the trip operation described above, even if the operation handle is moved to the OFF position, the stopper piece provided on the handle lever in the middle of the movement fits into the convex cam of the upper link. It is possible to secure the isolation function by preventing further movement of the handle.

Claims (4)

A circuit breaker equipped with a fixed contactor of a main circuit, a movable contact supported by a pivotal contact holder, an opening / closing mechanism linked to a contact holder, an operation handle, and an overcurrent trip device, wherein the opening / closing mechanism pivots the tip to the frame. A handle lever supported and coupled to the operation handle, one end of which is axially held in the frame, and a latch in which the leading pole part is engaged in the latching position and supported at a locking position, and an upper link and a harlink coupled through a toggle pin. And a toggle link that pivotally connects the other ends of the upper link and the lower link to the latch and the contact holder, respectively, and an assembly with an open / close spring extending between the toggle pin and the upper end of the handle lever. The main circuit contact is opened and closed by the ON / OFF operation of the handle, and when the overcurrent flows, the latch is released to trip the open / close mechanism. According to a to small, In the trip operation in the state of melt adhesion of the contact between the fixed and movable contacts, the latch can be slidably moved between the top link of the toggle link and the latch so that the latch can be rotated to the release position without being restrained by the upper link. Circuit breaker characterized in that the pivot connection. The method of claim 1, A U-shaped open bearing portion is formed on an upper end of the upper link, and the connecting shaft portion provided in the latch is engaged with the bearing portion so as to slidably pivot between the latch and the upper link. The method of claim 1, And a long hole bearing portion formed at an upper end of the upper link, and the connecting shaft portion provided in the latch is engaged with the long hole of the bearing portion so as to be slidably pivoted between the latch / uplink. The method according to any one of claims 1 to 3, An isolation mechanism that prevents the operation handle from moving to the OFF position while the main circuit contacts are melted. A convex cam is formed on the side edge of the upper link and the ON side of the handle lever is opposed to the convex cam. The circuit breaker characterized by the female stopper piece provided in the side.

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