JPH0133890B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in circuit breakers and breakers, particularly in their arc extinguishing devices.

Among current limiting circuits and disconnectors, there are some that have arc induction plates installed at the tips of the fixed and movable contacts, respectively, to make it easier for the arc to travel to the upper and lower parts of the grid of the arc extinguishing device. Generally, the fixed and movable induction arc plates are installed substantially parallel to each other and facing each other. Such a conventional circuit and disconnector is shown in FIG.

In the figure, 1 is a case, 2 and 3 are power supply side and load side terminals fixed to the case 1, respectively.
4 is a contactor part, 5 is an opening/closing mechanism, 6 is an arc extinguishing device, 7
is the overcurrent trip section. 8 is a fixed contact provided on the contact portion 4; 9 is a movable contact provided opposite thereto; 10 is a movable arm pivotally mounted with the center as a fulcrum; 11 is a bimetal; 12 is a solenoid; 13 is a handle for operation, 14 is a link connected to this handle, 15 is a receiver, 16 is an opening/closing spring, 17 is a latch, 18 is a plunger, 19 is a latch push rod, 20 is a grid of the arc extinguishing device 6, 21 2 is a side plate, 22 is a fixed arc plate, and 23 is a movable arc plate.

In the circuit breaker configured as described above, when the movable contact 9 separates from the fixed contact 8, an arc is generated between the fixed contact 8 and the movable contact 9. This arc moves to both induction arc plates 22 and 23, and by the action of the magnetic flux generated by the current flowing through both induction arc plates 22 and 23, the arc is driven in a direction away from the contact, that is, toward the arc extinguishing device 6. . The arc enters the grid 20 of the arc extinguisher 6 and is extinguished.

The above configuration is to quickly drive the arc from the contact portion to the arc extinguishing device when a large current such as a short circuit current is opened, thereby enhancing the current limiting effect.

By the way, according to the above conventional configuration, when a large current such as a short circuit current is opened, the arc driving force is large and the arc reaches the arc extinguishing device immediately, but when a small current near the rated load current is opened, The magnetic flux near the induction arc plate is weak, and the arc is jammed near the contact. That is, this has led to significant wear and tear on the contacts, resulting in problems such as poor contact.

This invention was made in order to eliminate the drawbacks of the conventional ones as described above, and aims to improve the arc driving effect even with a small current open circuit by improving the induction arc plate.

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 2, the breaker of the present invention includes a case 1, a power supply side terminal 2, a load side terminal 3, a contact part 4,
Opening/closing mechanism 5, arc extinguishing device 6, overcurrent tripping section 7
It consists of The electric circuit is formed by a power supply side terminal 2, a fixed contact 8, a movable contact 9, a movable arm 10, a bimetal 11 which is a time delay tripping element, a solenoid 12 which is an instantaneous tripping element, and a load side terminal 3. There is. Opening/closing mechanism 5 that opens and closes the electric circuit
is composed of a handle 13, a link 14, a receiver 15, a movable arm 10, and an opening/closing spring 16, and the overcurrent tripping section 7 is composed of a latch 17, a bimetal 11, a solenoid 12, a plunger 18, and a latch push rod 19. There is. 6 is the grid 20, side plate 21
22 is a fixed guide plate, 23 is a movable guide plate, which is rotatably supported at one end and biased clockwise by a torsion spring 24.

In the circuit breaker configured as described above, in order to open a small current near or below the rated load current, the handle 13 is rotated clockwise, the link 14 acts, and the movable arm 10 The movable contact 9 rotates counterclockwise about the central portion as a fulcrum, and the movable contact 9 separates from the movable contact 9 to generate an arc between it and the fixed contact 8. At this time, the arc is driven in the direction of the arc extinguishing device 6 by the magnetic flux of the reverse current flowing through the fixed contact 8 and the movable contact 9, which are arranged substantially in parallel. Moving on to plate 23. While the conventional induction arc plates 22 and 23 are arranged as shown in FIG. 3, the induction arc plates 22 and 23 of the present invention
23 are arranged substantially parallel and close to each other as shown in FIG. 4, the arc quickly jumps into the arc extinguishing device 6, the arc is extinguished, and the circuit is immediately broken. The shearing effect in the case of such a small current is as follows.

The driving force of the arc is expressed by the following equation.

f=iBl f: Driving force of conductor (arc) [N] B: Magnetic flux density [Wb/m ² ] i: Current of conductor (arc) [A] l: Effective length of conductor (arc) [m] Magnetic flux density B is the fixed side induced arc plate 2 due to the arc current.
2 and the magnetic flux generated by the current flowing through the movable guide plate 23. Therefore, the driving force f of the arc is proportional to the square of the self-current and inversely proportional to l.

In the case of FIG. 4, the distance l (arc length) between the fixed guide plate 22 and the movable guide plate 23 is smaller than in the conventional case shown in FIG. 3, and the arc resistance is reduced. As a result, the arc current becomes larger than in the conventional case, the driving force for the arc becomes larger, and the arc is easily transferred to the arc extinguishing device 6. At this time, the arc acts on only about half the number of grids 20, but since the current is small, it can be broken without any trouble. Furthermore, when a relatively large current such as a short circuit current flows, the bimetal 11 or solenoid 12 is activated, the engagement between the latch 17 and the holder 15 is released, the holder 15 rotates counterclockwise, and the link 14 acts, and the movable contact 9 opens. The arc moves to the fixed side induction arc plate 22 and the movable side induction arc plate 23 in the same way as above. At this time, since relatively large currents in opposite directions flow through the fixed induction arc plate 22 and the movable induction arc plate 23, large forces are generated in the respective repulsive directions, and as shown in FIG. Arc plate 23
rotates counterclockwise around one rotatably supported end against the force of the torsion spring 24. That is, the distance between the fixed-side induction arc plate 22 and the movable-side induction arc plate 23 increases. However, because the current is large, the magnetic flux to drive the arc is large enough.
Moreover, the arc acts on the total number of grid 20,
Disappears quickly.

As described above, according to the present invention, when a small current is opened, the movable induction arc plate is brought close to the fixed side induction arc plate at a predetermined distance to facilitate arc drive, and when a large current is opened, the movable induction arc plate is movable by electromagnetic repulsion. By rotating the side induction arc plate in the direction away from the fixed side induction arc plate and causing the arc to act on the entire length of the arc extinguishing device, wear and tear on the contactor can be significantly reduced, and the current limiting effect can be further improved. It is effective.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a conventional circuit and disconnector, FIG. 2 is a sectional view showing an embodiment of the present invention, FIG. 3 is an enlarged sectional view of a conventional arc extinguishing device, 4
5 and 5 are enlarged cross-sectional views of the arc extinguishing device section of an embodiment of the present invention, FIG. 4 shows a small current breaker, and FIG. 5 shows a large current breaker. It is something. In the figure, 1 is a case, 2 is a power supply side terminal, 3 is a load side terminal, 4 is a contact part, 5 is an opening/closing mechanism, 6 is an arc extinguisher, 7 is an overcurrent trip part, 8 is a fixed contact, 9 is a movable contact, 22 is a fixed side induction arc plate, 23
2 is a movable arc plate, and 24 is a torsion spring.

Claims (1)

[Claims] 1. A fixed contact, a movable contact provided opposite the fixed contact, and an opening/closing mechanism that opens and closes both of these contacts.
An overcurrent tripping section that automatically separates the movable contact from the fixed contact due to overcurrent; A fixed-side induction arc plate and a movable-side induction arc plate are arranged substantially parallel to each other toward the arc extinguishing device side. The induction arc plate is urged to approach the fixed side induction arc plate to a predetermined distance, and when a large current is opened, the movable side induction arc plate moves away from the fixed side induction arc plate due to electromagnetic repulsion. A circuit breaker characterized by being designed to rotate against force.