JPS61279028A - Overcurrent tripper for circuit breaker - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Technical field to which the invention pertains]

The present invention relates to overcurrent tripping devices for circuit breakers, particularly for thermal release.

[Prior art and its problems]

The operating time of the circuit breaker against overcurrent is, for example, the first
It is defined by JIS-C8370 shown in the table. As is clear from Tables 1 and 1, the tripping operation time when energizing at 200% of the rated current becomes shorter as the rated current becomes smaller. For this reason, the following two types of overcurrent release devices are used for circuit breakers with small rated currents in order to satisfy the standard operating time. Firstly, there is a part that protects the overload area where the circuit current flows directly through the bimetal, a thermal electromagnetic type that is made up of an electromagnet that operates with the large current that flows through the bimetal as a part that protects the short circuit area, and the next part is the oil dash pot. This is a completely electromagnetic type that uses both an electromagnet and an electromagnet. However, in the case of fully electromagnetic types, their use is decreasing due to the difficulty of reducing the price due to their complicated structure and the troublesome management of preventing oil leakage. An example of a thermal electromagnetic type in which the circuit current is passed directly through the bimetal is shown in Figure 7. An overcurrent release device is installed on the load side of the cutoff pole that is not connected to the cutoff pole. It consists of a fixed iron core 4 that is open and has a U-shape, and a movable iron core 5 that is swingably supported on the open side of the fixed iron core 4. The main components include an electromagnet 6 and a tripping mechanism 7 that is engaged and operated by the bending of the bimetal 3 and the suction action of the movable iron core 5. One end of the bimetal 3 is connected to a movable contact (not shown) via a connecting plate 8 and a connecting wire 9, and the other end is connected to a connecting wire 10 and a terminal conductor 11 to a load-side terminal 12. An adjusting screw 13 at the engagement point with the tripping mechanism 7 is screwed onto the other end of the bimetal 3 so that it can move forward and backward. The movable core 5 of the electromagnet 6 is biased toward the anti-attraction side by a spring 14, and a lever 15 that can be engaged with the tripping mechanism 7 is extended. Connection plate 8 and terminal conductor 11 are fixed to insulating case 1 by screws 16 and 17, respectively. A fixed contact (not shown) that comes into contact with and separates from the movable contact is connected to a power supply terminal 19 via a terminal conductor 18. In the above configuration, the overcurrent disconnection device operates between the bimetal 3 that flows directly, the fixed core 4 that surrounds the bimetal 3 and has a U-shaped opening on the power supply side (left side in the figure), and the open side of the fixed core 4. It consists of a movable iron core 5 that is swingably supported. Electromagnet 6 and bimetal 3 curved and movable core 5
The main component includes a tripping mechanism 7 that is engaged and operated by the suction operation of the holder. One end of the bimetal 3 is connected to a movable contact (not shown) via the connection plate 8 and the connection &19, and the other end is connected to the connection wire 10 and the terminal conductor 11 to the load side terminal 12. An adjusting screw 13 at the engagement point with the tripping mechanism 7 is screwed onto the other end of the bimetal 3 so that it can move forward and backward. The movable core 5 of the electromagnet 6 is biased toward the anti-attraction side by a spring 14, and a lever 15 that can be engaged with the tripping mechanism 7 is extended. The connecting plate 8 and the terminal conductor 11 are fixed to the insulating case l by screws 16 and 17, respectively. Note that a fixed contact (not shown) that comes into contact with and separates from the movable contact is connected to a power supply side terminal 19 via a terminal conductor 18 . In the above configuration, the operation of the overcurrent disconnection device is such that if an overcurrent in the overload region flows to the cutoff electrode, a corresponding amount of Joule heat will be generated in the bimetal 3 due to its own resistance and the flowing overcurrent. , the free end of the bimetal 3 is bent counterclockwise, and the tip of the adjustment screw 13 is connected to the tripping mechanism 7.
The shutoff operation is performed by rotating the switch counterclockwise to disengage it from an opening/closing mechanism (not shown). Furthermore, if a large fault current in the short-circuit region flows through the breaking pole, the bimetal 3 will naturally heat up and bend, but before that, the magnetic flux generated in the fixed core 4 will resist the force of the spring 14 and move the movable core 3. is sucked, and the tip of the lever 15 performs a shutoff operation via the tripping mechanism 7 and the opening/closing mechanism in the same way as in the case of an overload area. However, in the case of this configuration, if a large current such as an accident current flows through the bimetal 3 until the interruption is completed, as described above, the bimetal 3
This has the disadvantage that permanent deformation and melting occur, making it unsuitable for use in electrical circuits with large short-circuit capacity.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide an overcurrent 4 disconnection device for a direct heating type thermal electromagnetic circuit breaker which eliminates the above-mentioned conventional drawbacks and can be used in electrical circuits with large short circuit capacities.

[Key points of the invention]

The gist of this invention is to achieve the above-mentioned object by providing a fixed iron core that is arranged so as to surround a bimetal that bends when an overcurrent occurs when a current is directly passed through it, and that is open on the negative side; A movable core that is swingably supported and is attracted to the fixed core against a return spring when the circuit current becomes a fault current, and a tripping mechanism that is operated by the movable core when the movable core is attracted and when the bimetal is bent. and,
A fixed contact installed on the opening side of the fixed iron core and connected to one end of the bimetal, and a movable contact attached to the movable iron core so as to be able to come into contact with and separate from the fixed contact and connected to the other end of the bimetal, The purpose is to prevent damage by forming a bimetallic shunt circuit by attracting the movable iron core due to the flow of fault current.

[Embodiments of the invention]

1 and 2 are diagrams showing an embodiment of the overcurrent 4 disconnection device for a circuit breaker according to the present invention. In the figures, the same parts as those of the conventional device shown in FIG. I will explain the differences to avoid redundant explanations. The difference between this embodiment and the conventional device is that a shunt circuit is provided between the fixed core 4 and the movable core 5 of the electromagnet 6, which is closed during the suction operation of the movable core 5 and short-circuits both ends of the bimetal 3. The six branch circuits have a supporting piece 21 fixed to the inner wall of one leg of the fixed iron core 4 with rivets 20 and bent along the end faces of both side pieces, and a movable iron core 5 of the supporting piece 21 facing each other. A fixed contact 23 is integrated with the side by brazing or the like and connected to the terminal conductor 11 of the load side terminal 12 via a tangential M wire 22.
The movable contact 25 faces the fixed contact 23 and is integrally integrated with the movable iron core 5 by brazing or the like so as to be able to come into contact with and separate from it, and is connected to the connection plate 8 via a connection wire 24. As a result, the movable contact 25 is connected to one end (lower side in the figure) of the bimetal 3 via the connecting wire 24 and the connecting plate 8, and the fixed contact 23 is connected to the connecting wire 22. It is connected to the other end (upper side in the figure) of the bimetal 3 via the terminal conductor 11 and the connecting wire 10, and therefore, a shunt circuit of the bimetal 3 is formed by opening the movable contact 25 and the fixed contact 23. The resistance of the shunt circuit must be small (it must be lower than the resistance of the bimetal 3, and preferably it is as small as possible.
For example, the material may be a conductive material. The operation of the above-mentioned configuration will be explained. First, in the overload region, the operation is similar to that of the conventional device shown in FIG. 7 described above. In the short-circuit region, when a fault current flows through the bimetal 3, the movable core 5 is immediately attracted to the fixed core 4, so the movable contact 25 and the fixed contact 23 are closed, short-circuiting both ends of the bimetal 3. The lever 15 operates the opening/closing mechanism via the tripping mechanism 7 to open the circuit breaker. Due to this process, the current in the bimetal 3 becomes significantly smaller at the same time as the short circuit occurs because a shunt circuit is formed from when the movable core 5 is attracted to when the cutoff is completed in the short-circuit region. Therefore, the bimetal 3 will not be permanently deformed or fused. Next, different embodiments of the overcurrent 4 disconnecting device for a circuit breaker according to the present invention will be explained with reference to FIGS. 3, 4, 5, and 6. First, in the embodiment shown in FIGS. 3 and 4, the difference between this embodiment and the embodiment shown in FIG. The support leg 4a is bent and extended to the side leg piece, and the fixed contact 23 is attached to the support leg 4a by brazing or the like. Therefore, although this embodiment has the advantage of being able to reduce manufacturing costs over the previous embodiments, there is a limit to the reduction in the resistance value of the shunt circuit, so there remains a restriction on the size of the short circuit capacity of the electrical circuit used. Next, in the embodiment shown in FIGS. 5 and 6, the difference between this embodiment and the embodiments shown in FIGS. 1 and 3 is that the connecting wire between the fixed contact 23 and the terminal conductor 11 2
By winding the magnet 6 around the fixed iron core 4 in the form of a coil, it is possible to compensate for a decrease in the attractive force due to a decrease in ampere turns of the electromagnet 6 after the shunt circuit is closed. This means that the resistance of the shunt circuit is the same as that at the start of suction from the end of suction to the completion of shutoff, that is, both the fixed and movable contacts 23 and 25
The contact pressure between the two is maintained until just before the shutoff is completed. In this embodiment, the connecting wire 26 connects the fixed iron core 4 to I.
Although the winding is Z-turn, it goes without saying that the winding is not limited to this. From the above, in this embodiment as well, the resistance of the shunt circuit, including the contact resistance between the contacts, is stabilized, making it possible to use it in an electrical circuit with a large short-circuit capacity.

【Effect of the invention】

According to this invention, a shunt circuit is provided at both ends of the directly heated bimetal for overload region protection, which is closed by electromagnetic operation for short circuit region protection, and this shunt circuit is wound around the fixed core of the electromagnet to excite it. By using this configuration in combination with this, it is possible to provide an overcurrent release device for a circuit breaker that can be used for small current and large short-circuit capacity electrical circuits.

[Brief explanation of drawings]

1 and 2 show a first embodiment of an overcurrent disconnection device for a circuit breaker according to the present invention;
The figure is an enlarged perspective view of the main parts, FIG. 2 is a side view of the circuit breaker showing a cross section of the main parts, and FIGS. 3 and 4 are a second embodiment of the overcurrent release device for a circuit breaker according to the present invention. and the third
FIG. 4 is a side view of the circuit breaker showing a cross section of the main part, and FIGS. 5 and 6 show a third embodiment of the overcurrent release device for a circuit breaker according to the present invention. For example, Fig. 5 is an enlarged perspective view of the main part, Fig. 6 is a side view of the circuit breaker showing a cross section of the main part, and Fig. 7 is the main part of an example of a conventional overcurrent release device for a circuit breaker. FIG. 3 is a side view showing a cross section. 3: Bimetal, 4: Fixed core, 5: Movable core, 7: Tripping mechanism, 22, 24, 26: Connection wire, 23: Fixed connection Figure 1 Figure 2 Figure 5 Figure 6

Claims (1)

[Scope of Claims] 1) A fixed core that is arranged to surround a bimetal that bends when an overcurrent occurs when a current is directly passed through the circuit, and is open on one side, and a fixed core that is swingably supported on the open side of the fixed core; a movable core that is attracted to the fixed core against a return spring when the circuit current becomes a fault current, a tripping mechanism that is operated by the movable core when it is attracted and when the bimetal is bent, and the fixed core. A fixed contact installed on the opening side and connected to one end of the bimetal, and a movable contact attached to the movable core so as to be able to come into contact with and separate from the fixed contact and connected to the other end of the bimetal. Overcurrent tripping device for circuit breakers. 2) In the overcurrent tripping device for a circuit breaker according to claim 1, the circuit breaker is characterized in that the connecting conductor between one end of the bimetal and the fixed contact is wound around a fixed core an arbitrary number of times. overcurrent trip device.