JPH09171762A - Circuit breaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the breaker which effectively cool each arc so as to guide it to a discharge port, and also excellent in breaking property against large current. SOLUTION: A movable contact base insertion part 8 is formed on the side faced to the rotation center of a movable contact base 7 in an arc-extinguishing chamber, and an arc discharge port 4 is formed at the side opposite to the movable contact base insertion part 8 of the arc-extinguishing chamber. An arc-extinguishing device is disposed at a place which is located at the arc discharge port side while being opposite to the rotating locus of the movable contact base 7 on the inside of the arc-extinguishing chamber, and the arc discharge port 4 is also disposed at a place close to a place where the opening operation of the movable contact base 7 ends up. This constitution thereby enables each arc to be cooled by an arc-distinguishing plate for being guided to the discharge port 4 before the opening operation of the movable contact base 7 ends up.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit breaker, and more particularly to a constituent member of an arc extinguishing section, insulation, arc drive, and pressure rise caused by arc energy. It relates to a circuit breaker suitable for prevention. A conventional device is disclosed in Japanese Utility Model Laid-Open No. 1-60439. For example, in many conventional circuit breakers, an arc extinguishing device 5 is mounted inside an insulating casing 1 as shown in FIG. 6, but the internal pressure raised by the arc generated in the arc extinguishing device is applied to the insulating casing. It acts directly, and as shown in FIG. 7, it receives the internal pressure of the arrow P and many accidents of destruction of the casing inner wall occur. Therefore, it is necessary for the casing to withstand the above-mentioned internal pressure, and in order to increase the breaking ability corresponding to a large current at the time of breaking, it is necessary to take measures such as increasing the strength of the casing material or suppressing an increase in the internal pressure. As this means, for example, glass reinforced plastics are adopted, or compression molded products having higher strength than injection molded products are adopted, and as a measure for reducing the internal pressure, expansion of the arc extinguishing chamber volume is implemented. As shown in FIG. 8, the molded case of the circuit breaker has a high case component cost to manufacturing cost ratio of 25 to 35%. Further, as shown in FIG. 9, the compression molded product has high strength, but the difference between the component cost a2 and the material cost a1 is large, and the glass fiber reinforced molded product has almost the same relationship between the component costs c2 and c1. Indicates that the processing cost becomes high, and the strength of the injection molded product is small, and the difference between the component cost b2 and the material cost b1 is small. As described above, the production of the compression-molded casing has a high strength, but causes a significant cost increase, and the increase in volume is a problem because it is against the downsizing of the circuit breaker and the reduction of the storage space of the switchboard and the like. In addition, in order to drive the arc at the time of breaking rapidly in a predetermined direction to cool and surely extinguish the arc, and
An arc extinguishing plate, a driving member, an insulating plate, etc. are provided in the arc extinguishing device in order to ensure the insulation between the power source and the mechanism part during or after the interruption, but the structure increases the number of parts. As a result, the assembly becomes difficult due to the complexity of the above, and the individual members also become large in size, which inevitably increases the cost.
There was a trade-off between securing the breaking performance and improving the insulation and reducing the cost. According to the present invention, the arc extinguishing chamber is formed of a material having higher pressure resistance and insulation than the casing, and the arc discharge port is disposed in the vicinity of the position where the opening / closing operation of the movable contact base is completed to generate the arc. It is an object of the present invention to provide a circuit breaker which is effectively cooled and led to the discharge port and has an excellent breaking property against a large current. In order to achieve the above object, the present invention provides a movable contact base rotatably provided, a fixed contact base, and a movable contact in response to the occurrence of an accident current. A circuit breaker in which a contact opening / closing mechanism for opening the base from a fixed contact base and an arc extinguishing device for driving or cooling the arc generated between the contacts when the contacts are opened are housed in the casing. And an arc extinguishing chamber for accommodating the movable contact base and the arc extinguishing device therein. The arc extinguishing chamber is formed of a material having higher pressure resistance and insulation than the casing, and is provided at the center of rotation of the movable contact base. The movable contact base insertion part formed on the facing side and the arc discharge port formed on the side facing the movable contact base insertion part, respectively, and the arc discharge position is the position where the opening operation of the movable contact base ends. Placed near It is characterized by the following. Since the arc-extinguishing chamber is arranged in each of the poles in the casing and made of an insulating material having pressure resistance, the arc-extinguishing chamber protects the casing against an increase in internal pressure due to an arc generated at the time of interruption. be able to. This makes it possible to use a material having low strength for the casing. Further, since the internal pressure when the arc is generated can be received in the arc extinguishing chamber, the thickness of the casing can be made thin, and the material of the casing can be reduced and the size and weight can be reduced. Since the arc extinguishing chamber is provided with the movable contact base insertion portion formed on the side facing the center of rotation of the movable contact base and the arc discharge port formed on the side facing the movable contact base insertion portion, respectively, The arc chamber has a structure in which the peripheral wall excluding the movable contact point insertion portion and the arc discharge port is closed to prevent arc leakage from other than the discharge port. Since the arc discharge port is disposed near the position where the opening / closing operation of the movable contact base ends, the arc can be cooled by the arc extinguishing plate and discharged from the discharge port until the opening / closing operation of the movable contact base ends. Embodiments of the present invention will be described below with reference to FIGS. A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a perspective view showing the interior of the arc extinguishing chamber of this embodiment, and FIG.
1 is an exploded perspective view of FIG. 1, in which an arc generated between a movable contact base 7 that opens in response to the occurrence of a fault current and a fixed contact base 6 corresponding to the movable contact base 7 has contact points 6a, A high temperature gas is generated while sublimating 7a, the contact bases 6 and 7 and the adjacent members. The arc column generated between the contacts 6a and 7a extends along with the opening / closing operation of the movable contact base 7, and the U-shaped arc extinguishing plate 3 composed of a plurality of magnetic plates is arranged so as to surround the arc column. It is cooled while being driven to the power supply side, and is discharged from the arc gas discharge port 4 provided on the power supply side. The extended arc column is cooled by the arc extinguishing plate 3, becomes a higher impedance, suppresses the arc current, and finally reaches the current zero point, so-called interruption. Since the arc outlet is located near the position where the opening operation ends, the number of arc extinguishing plates involved in cooling the arc increases and the arc is cooled by the arc extinguishing plate until the opening operation of the movable contact block ends. Then, the arc is efficiently cooled and discharged from the discharge port 4. As shown in FIG. 2, the arc-extinguishing chamber in this embodiment is formed by a casing 2 made of a high-strength insulating material for each pole and an arc-extinguishing plate 3 housed inside. Since the housing 2 receives the internal gas pressure at the time of generation, the insulating casing 1 which is the outer shell of the circuit breaker can be constructed with a relatively reduced strength. As shown in FIG. 3, the arc-extinguishing chamber has a fixed contact arranged at the bottom thereof so that the fixed contact faces the movable contact, and the opening 8 is opened and closed on the side facing the rotation center of the movable contact base of the housing 2. It is formed along the locus of the insulating base 7. The movable contact base 7 is inserted through the opening 8 and functions as a movable contact base insertion portion. Case 2
Is capable of suppressing the arc generated between the contacts from flowing out to the opening / closing mechanism part side or the operating handle side by closing the parts other than the opening part 8 provided along the locus of the movable contact base 7 that opens and closes. . Further, at the mounting portion of the fixed contact base 6, only the fixed contact 6a and the arc runner 9 provided there are exposed in the housing 2, and the other portions are covered with an insulating plate. The arc column base on the side closer to the fixed contact 6a quickly moves along the arc runner 9 without diverging and the concentration of the arc is strengthened, so that the arc impedance is further increased and the suppression of the passing current is further strengthened. . A second embodiment of the present invention will be described with reference to FIG. According to this embodiment, a plurality of arc extinguishing plate support grooves 2a are provided inside the housing 2, and the arc extinguishing plate 3 is mounted through the support grooves 2a, whereby the arc extinguishing chamber can be integrated. Further, the U-shaped magnetic body 10 is attached to the outside of the housing 2, and the opening operation of the movable contact base 7 is configured to be accelerated by the magnetic flux along the U-shaped magnetic body 10. If the magnetic body 10 is moved as close as possible along the rotation trajectory of the movable contact base 7, a faster opening operation can be obtained. A U-shaped guide 2b is provided on a part of the housing 2.
It is preferable that the U-shaped magnetic body 10 is mounted in parallel with the side wall of the housing 2 so as to prevent a decrease in impedance due to an arc contact and obtain a reliable insulating effect. Further, similar to that shown in FIG. 3, a convex bank portion 11 is formed on the opening / closing mechanism portion side of the housing 2, that is, on the outer side of the lower portion of the opening 8, and serves as a fixed contact base 7 during and after interruption. Insulation with the opening / closing mechanism is strengthened. The insulating casing 1, the opening / closing mechanism, etc. are the same as in the first embodiment. A third embodiment of the present invention will be described with reference to FIG. In the present embodiment, as shown in FIG. 5, a pair of prevention walls 1 facing the side wall of the housing 2 and facing each other along the locus of the movable contact stand.
By providing 2, it is possible to prevent the arc transfer to the tip side of the U-shaped arc extinguishing plate 3, and it is effective to promote the concentration and rapid movement of the arc. The insulating casing 1, the opening / closing mechanism, etc. are the same as in the first embodiment. In the above embodiment, the housing 2 may be constructed by assembling at least two molded products or plate-shaped products, for example, a molded product by a ceramic mold, or an outer shell made of a metal on the inner wall. It may be coated with a material having excellent insulation and arc resistance. According to the present invention, the arc is cooled by the arc extinguishing plate and guided to the discharge port until the opening / closing operation of the movable contact base is completed.
It is possible to obtain a circuit breaker excellent in breaking property against a large current.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a main part inside a circuit breaker according to a first embodiment of the present invention. FIG. 2 is an exploded perspective view of a main part of the circuit breaker according to the first embodiment of the present invention. 3A and 3B are views showing the structure of the housing in the first embodiment of the present invention, FIG. 3A is a side sectional view, and FIG. 3B is a perspective view seen from the movable contact base side. FIG. 4 is an exploded perspective view of a housing according to a second embodiment of the present invention as viewed from the arc outlet side. FIG. 5 is a plan sectional view of a housing according to a third embodiment of the present invention. FIG. 6 is a perspective view of a conventional arc extinguishing device and a casing. FIG. 7 is a chart showing the internal pressure generation state of a conventional casing. FIG. 8 is a view showing materials and cost ratios of the arc extinguishing device and the casing. FIG. 9 is a diagram showing a relationship between strength and cost of materials of an arc extinguishing device and a casing. [Explanation of Codes] 1 ... Insulating casing 2 ... Housing 3 ... Arc extinguishing plate 4 ... Arc discharge port 6 ... Fixed contact base 6a ... Fixed contact 7 ... Moving contact Platform 7a ... Movable contact 8 ... Opening 9 ... Arc runner 10 ... U-shaped magnetic material 11 ... Convex bank

Claims (1)

[Claims] 1. Between the movable contact table rotatably provided, the fixed contact table, the contact opening / closing mechanism for opening the movable contact table from the fixed contact table in response to the occurrence of the accident current, and the contact between the contacts when the contact is opened. An arc extinguishing device for driving or cooling an arc generated in a casing, the arc extinguishing being housed in the casing and containing the movable contact base and the arc extinguishing device therein. A chamber, the arc-extinguishing chamber is made of a material having higher pressure resistance and insulation than the casing, and the movable contact point insertion portion formed on the side facing the center of rotation of the movable contact point and the movable contact point A circuit characterized by comprising arc discharge ports formed on the side facing the contact point insertion part, and the arc discharge ports are arranged in the vicinity of the position where the opening / closing operation of the movable contact point ends. Circuit breaker.