JP4419642B2 - Circuit breaker arc extinguishing device - Google Patents

Description

  The present invention relates to an arc extinguishing device equipped in a current interrupting part of a circuit breaker intended for a circuit breaker for wiring, an earth leakage breaker and the like.

First, the conventional structure which employ | adopted the arc-extinguishing grid as an arc-extinguishing apparatus of the electric current interruption part of the circuit breaker mentioned above is shown in FIG. 3 (for example, refer patent document 1). In the figure, 1 is a fixed contact having a tip contact portion formed in a U-shape, 2 is a rotary movable contact, 3 is an arc runner connected to the contact portion of the fixed contact 1, and 4 is an opening of the movable contact 2. The arc extinguishing grid is formed by laminating a plurality of grid plates 4a with a gap therebetween along the pole movement path.
With the above configuration, the movable contact 2a of the movable contact 2 is in contact with the fixed contact of the fixed contact 1 (not shown hidden behind the arc extinguishing grid 4 in FIG. 3) during normal energization. Here, when an overcurrent such as a short-circuit current flows through the main circuit, an electromagnetic repulsive force is generated between the fixed contact 1 and the movable contact 2 due to the magnetic field of the current flowing through the fixed contact 1 and the movable contact 2. When the electromagnetic repulsion force exceeds the load of the contact pressure spring (not shown) of the contact, the movable contact 2 is detached from the fixed contact 1 toward the open position, and at the same time, an arc is generated between the fixed contact and the movable contact. Arc is ignited and expands along with the opening movement of the movable contact. In addition, the arc is movable, receiving the electromagnetic force due to the magnetic field of the current flowing through the stationary contact, the arc firing point (arc leg) of the stationary contact moves from the stationary contact to the arc runner 3, and is further divided by the grid plate 4a. As is well known, the arc voltage is rapidly increased and a cooling action is also added, whereby the current is interrupted.

In addition, as an arc extinguishing device for a circuit breaker, an arc extinguishing chamber is configured by combining a magnetic material and an insulator instead of using the arc extinguishing grid 4, and an arc generated between fixed / movable contacts when current is interrupted. An ablation effect is also added, in which the arc is compressed by being pushed into a slit formed in the arc extinguishing chamber insulator by electromagnetic driving force, and further, the insulator that has received the arc heat generates pyrolytic gas to cool the arc. A narrowing arc extinguishing system that increases the arc voltage is also known (see, for example, Patent Document 2).
JP-A-7-226144 Japanese Examined Patent Publication No. 7-93094

By the way, the circuit breaker and the earth leakage circuit breaker that employ the conventional arc extinguishing device according to the above-described method have the following problems in terms of structure and breaking performance. That is,
(1) Products such as circuit breakers for wiring have standardized external sizes for each frame, and there is a limit to increasing the capacity of the current interrupting part. Therefore, in the grid arc extinguishing system described in FIG. 3 (Patent Document 1), an arc extinguishing grid plate that expands the space for sufficiently extending the arc generated between the fixed / movable contacts and divides the arc in series. There is a limit to the increase in the number of sheets.
(2) Moreover, in the arc extinguishing chamber of the insulator disclosed in Patent Document 2, the arc generated between the poles of the fixed / movable contact is pushed into a slit formed in the insulator and narrowed down. In the circuit breaker of several tens of KVA class, the diameter of the arc column generated between the fixed / movable contacts when the current is interrupted expands to 10 mm or more, so it is powerful to push the arc thus spread into the narrow slit of the insulator. In fact, it is difficult to achieve the required electromagnetic driving force. In addition, the current limiting effect of the arc due to the narrowing in the slit is exhibited after the arc generated after the start of the opening operation of the movable contact is received by the electromagnetic force and pushed into the slit of the insulator. The time delay until the arc moves to the slit of the insulator affects the breaking performance of the circuit breaker.

Furthermore, for the arc generated between the poles, on the fixed contact side, the arc foot moves on the arc runner by the electromagnetic force and is driven inward of the arc extinguishing chamber to receive the arc extinguishing action. Since it moves to the opening position through the outside of the arc extinguishing chamber, the arc extinguishing function by the arc constriction of the arc extinguishing chamber does not act on the leg portion of the arc extending from the contact point of the movable contact at the opening position.
The present invention has been made in view of the above points. The object of the present invention is to solve the above-mentioned problems, and requires a pushing drive with respect to an arc generated between a fixed / movable contact when a current is interrupted with a simple structure. It is another object of the present invention to provide an arc extinguishing device for a circuit breaker in which the arc extinguishing function by effectively constricting the arc acts effectively even at the open position of the movable contact so as to improve the breaking performance.

In order to achieve the above object, according to the present invention, in a circuit breaker that performs current interruption by opening a movable contact from a fixed contact when an overcurrent is applied to a main circuit, the movable contact of the movable contact is comprising an insulator made of an arc barrier that surrounds the contact tip comprising, said arc barrier comprises a box body of U-shaped, counter-movable contact side of the contact tip of the movable contact a central side of the U-shaped as well as attached to, those wherein the tips of the left and right side walls by extending the fixed contact terminal side of the U-shaped, the arc that arcing between the fixed contacts and the movable contact upon current interruption to refine within said arc barrier And
Further, in the arc extinguishing apparatus, it is preferable that the arc barrier is made of a highly heat-resistant ceramic or an insulating material of a hydrocarbon resin that generates a gas upon contact with a high temperature arc.

According to the above-described invention , the arc generated between the fixed / movable contacts at the same time as the opening operation of the movable contact is started is narrowed down inside the arc barrier that is mounted on the movable contact and surrounds the contact portion. This state continues even in the process in which the movable contact moves to the opening position immediately after it is separated from the fixed contact. Therefore, unlike the conventional arc extinguishing apparatus (see Patent Document 2), it is not necessary to drive the arc by pushing it into the insulator slit of the arc extinguishing chamber located away from the contact, so that it is possible to narrow the arc without time delay. The current limiting function by (compression, cooling) acts, and this shortens the current interruption time and improves the interruption performance of the circuit breaker.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on the examples shown in FIGS.

1A and 1B show a first embodiment of the present invention. In this embodiment, as compared with the conventional structure shown in FIG. 3, the movable contact 2 is equipped with an arc barrier 5 made of an insulator so as to surround its tip. The arc barrier 5 is made of a highly heat-resistant ceramic or a box made of a thermoplastic or thermosetting hydrocarbon resin that generates a large amount of pyrolysis gas when exposed to a high-temperature arc, and is formed into a U shape as shown in the figure. In the structure, the distal ends of the left and right side walls are directed downward (on the fixed contact side) so as to surround the distal end portion including the contact 2a of the movable contact 2 and are coupled across the back surface. Further, the arc barrier 5 has a left-right width D that is approximately the same as the plate thickness d of the movable contact 2 to form a narrowing gap between the left and right side walls, and the vertical length of the left and right side walls is L. The tip is extended toward the fixed contact 1. In addition, you may make it this arc barrier 5 extend in the front-end | tip direction of a movable contact so that the front-end | tip part (left side of FIG. 1) of a movable contact may be covered. In addition, the fixed contact 1 is narrowed to the width of the tip end portion as much as the plate thickness d of the movable contact 2, and a fixed contact 1a is provided on the upper surface thereof.

In addition to the arc barrier 5, a plurality of arc extinguishing grids 4 are arranged in the opening movement path of the movable contact 2 in the same manner as in FIG. 3, and the concave grooves cut out on the plate surface of the grid plate 4a are arranged. The arc barrier 5 is moved to the opening position together with the movable contact 2 through the inside.
With the above configuration, the arc barrier 5 surrounds the fixed contact 1a and the movable contact 2a in a closed state where the contact 2a of the movable contact 2 is in contact with the contact 1a of the fixed contact 1. Here, when the movable contact 2 is separated from the fixed contact 1 by the electromagnetic repulsion force caused by the overcurrent, an arc is generated between the contact points of the fixed contact 1 and the movable contact 2 as shown in FIG. The arc Arc is narrowed down between the left and right side walls of the arc barrier 5 immediately after the start of the opening operation, and at the same time receives a cooling action due to the ablation effect described above. In addition, the state of arc constriction by the arc barrier 5 continues even when the movable contact 2 moves toward the opening position, and the contact 1a of the fixed contact 1 and the contact 1a of the fixed contact 1 are moved along with the opening movement of the movable contact 2. The arc extending during this period is transferred to the arc runner 3 by electromagnetic force, and the arc column portion is further divided by the arc extinguishing grid plate 4a to be subjected to a current limiting action. That is, the arc Arc ignited when the current is interrupted and extended between the poles is subjected to the arc extinguishing action of the arc barrier 5 and the arc extinguishing grid plate 4a without time delay, and the arc disappears in a short time, and the current Current limiting is interrupted.

FIG. 2 shows a second embodiment of the present invention. In this embodiment, a movable contact 2 is formed by combining a U-shaped box-shaped arc barrier 5 made of the same insulator as described in the first embodiment with an arc extinguishing grid 4 in which grid plates 4a are laminated. The contact 2a of the movable contact 2 that has moved to the opening position when the current is interrupted is drawn into the slit between the left and right side walls of the arc barrier 5. In the illustrated embodiment, the left and right side plates 4b of the arc extinguishing grid that holds the grid plate 4a in the assembly position are extended upward to fix the arc barrier 5 here.
In the above configuration, when the movable contactor 2 moves to the illustrated opening position by the opening operation of the circuit breaker, the tip of the movable contactor 2 including the movable contact is between the left and right side walls of the arc barrier 5. Enter. Therefore, the arc column portion of the arc Arc that is ignited and extended between the stationary contact 1 and the movable contact 2 when the current is interrupted is divided into a series arc by the arc extinguishing grid plate 4a, and further the opening of the movable contact 2 is performed. At the pole position, the part of the arc leg extending above the arc extinguishing grid device 4 is drawn into the arc barrier 5 together with the movable contact, and is narrowed down by a slit between the left and right side walls of the arc barrier 5. A strong arc extinguishing action is applied. As a result, it is possible to ensure a high breaking performance as compared with the arc extinguishing device having the conventional structure shown in FIG.

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram of the electric current interruption part concerning Example 1 of this invention, (a) is an external appearance perspective view of an assembly structure, (b) is a perspective view in the state which removed the arc-extinguishing grid board in (a). The structure perspective view of the electric current interruption part concerning Example 2 of this invention. Configuration perspective view of current interrupting part with conventional structure equipped with arc extinguishing grid plate

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fixed contact 1a Fixed contact 2a Movable contact 2 Movable contact 3 Arcrunner 4 Arc extinguishing grid 5 Arc barrier Arc Arc

Claims (2)

In a circuit breaker that opens a movable contact from a fixed contact when an overcurrent is passed through a main circuit, and interrupts the current, an arc barrier made of an insulator that surrounds the contact tip including the movable contact of the movable contact With
The arc barrier is formed of a U-shaped box, and the U-shaped central side is mounted on the non-movable contact side of the contact tip of the movable contact, and the tips of the U-shaped left and right side walls are fixed contacts. An arc extinguishing device for a circuit breaker that extends to the side and narrows down an arc that is generated between a fixed contact and a movable contact when the current is interrupted.   2. The arc extinguishing apparatus according to claim 1, wherein the arc barrier is an insulator of ceramic or hydrocarbon resin.

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