JPH0982205A - Circuit breaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize an arc-extinguishing device, by making it possible to reduce a groove width of a U-shaped groove by employing a heat resistant magnetic arc- suppressing plate which allows a composite plating layer to be easily formed on an inner surface of the U-shaped groove. SOLUTION: A composite plating layer 7, is made in such a manner that ceramic particles of silicon carbide or boron nitride or the like are dispersed in a non- electrolytic nickel plating liquid and separated out, in a eutectoid manner, on a surface of an acid metal plate 71 . The silicon carbide has a subliming temperature of, for example, 2200 deg.C and a melting point higher than 2700 deg.C, while a subliming point at a normal temperature and a melting point at a higher pressure of the boron nitride are both 3000 deg.C, and therefore the composite plating layer 72 endures a high temperature generated by an arc. This layer 72 only needs a thickness on the order of 10μm to produce a sufficient effect and a heat resistant magnetic arc-suppressing plate 7 can do substantially without a thickness beyond that of the magnetic metal plate 71 , and therefore disposition of a plurality of plates becomes possible and an arc- extinguishing device can be miniaturized. The composite plating layer 72 is not limited to the said composition, but any combination will do so long as it is of a metal, which is excellent in heat resistance without damaging arc-extinguishing property, and a ceramic.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an arc extinguishing device, and more particularly to a circuit breaker in which a magnetic arc extinguishing plate has good arc resistance.

[0002]

2. Description of the Related Art FIG.
FIG. 4 is a perspective view of an arc extinguishing device in a conventional circuit breaker described in Japanese Patent Publication No. 8 and FIG. 4 is a diagram illustrating the relationship between the arc extinguishing device and the contacts. In the figure, 1 is a fixed contact, 2 is a movable contact,
3 is an arc extinguishing device, 4 is a magnetic arc extinguishing plate, 5 is a heat-resistant arc extinguishing plate, and 6 is a side plate. The magnetic arc-extinguishing plate 4 is made of a magnetic metal plate, and its main plane intersects with the moving direction of the movable contact 2, and the moving space of the movable contact 2 is surrounded by a U-shaped groove provided in the center thereof. And is fixed to the side plate 6 of the insulator. The heat-resistant arc-extinguishing plate 5 is made of a ceramic plate formed in substantially the same shape as the magnetic arc-extinguishing plate 4, and is bonded to the magnetic arc-extinguishing plate 4.

In the arc-extinguishing device for such a circuit breaker, since the heat-resistant arc-extinguishing plate 5 covers the surface of the magnetic arc-extinguishing plate 4, the magnetic arc-extinguishing plate 4 is not directly exposed to the arc.
The circuit breaker has a large breaking capacity and high durability.

[0004]

In the arc-extinguishing device in the conventional circuit breaker as described above, the magnetic arc-extinguishing plate 4 and the ceramic arc-extinguishing plate 5 are attached to each other. The magnetic metal is exposed on the cross section of the V-shaped groove. Since this exposed portion is closest to the arc and may be melted by contact with the arc, it is necessary to widen the groove width of the U-shaped groove, which makes it difficult to miniaturize the arc extinguishing device. Further, since the thickness of one composite arc extinguishing plate in which the ceramic arc extinguishing plate 5 is bonded to the magnetic arc extinguishing plate 4 becomes large, it becomes an obstacle when the arc gas moves into the arc extinguishing device. To solve this problem, the arc extinguishing device may be enlarged, but the circuit breaker becomes larger. On the other hand, if the number of the magnetic arc extinguishing plates 4 is reduced, the magnetic path cross-sectional area is reduced, so that the driving force of the arc is reduced, and the arc extinguishing effect of the arc is reduced.

The present invention has been made to solve the above problems, and is strong against arc heat at the time of current interruption,
It is to realize a circuit breaker that is small, has excellent breaking performance, and is durable.

[0006]

In the arc-extinguishing device according to the present invention, the surface of the arc-extinguishing plate is subjected to composite plating in which ceramic is co-deposited.

Further, it is a composite plating in which nickel carbide is co-deposited with silicon carbide or boron nitride.

Further, the arc-extinguishing plate of the portion that is frequently exposed to the arc is subjected to the composite plating.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1. FIG. 1 shows a heat-resistant magnetic arc-extinguishing plate of a circuit breaker according to the present invention. In FIG, 7 is a heat-resistant magnetic extinguishing plate subjected to composite plating process, magnetic metal plate ₇₁
A composite plating layer 7 ₂ is formed on the surface of the. The composite plating layer 7 ₂ is formed by dispersing ceramic particles such as silicon carbide or boron nitride in an electroless nickel plating solution and co-depositing on the surface of the magnetic metal plate 7 ₁ . Silicon carbide has a sublimation temperature of 2200 ° C. and a melting point of 2700 ° C. or higher. Boron nitride has a sublimation point of 3000 ° C. under normal pressure and a melting point of 30 under high pressure.
Since the temperature is 00 ° C., the composite plating layer 7 ₂ can withstand the high temperature caused by the arc. The composite plating layer 7 ₂ can exhibit a sufficient effect with a thickness of about 10 μm, and since the heat-resistant magnetic arc-extinguishing plate 7 substantially requires the thickness of the magnetic metal plate 7 ₁ , a large number of sheets can be arranged. Further, since the heat resistant magnetic arc-extinguishing plate 7 can easily form the composite plating layer 7 ₂ on the inner surface of the U-shaped groove, U
The groove width of the V-shaped groove can be reduced, and the arc extinguishing device 3 can be downsized. It goes without saying that the composite plating layer 7 ₁ is not limited to the above-mentioned structure, and may be a combination of metal and ceramic having excellent heat resistance without impairing arc extinguishing performance.

FIG. 2 is a sectional view of an arc extinguishing device portion of a circuit breaker to which the heat-resistant magnetic arc extinguishing plate according to the present invention is applied. The same or corresponding portions as those in FIGS. 3 and 4 are designated by the same reference numerals. ing. Composite plating is more expensive than plating for corrosion and rust prevention. Therefore, a heat-resistant magnetic arc-extinguishing plate 7 that has been subjected to composite plating is provided at a site that is frequently exposed to an arc, and a magnetic arc that is not subjected to composite plating is provided at a site that is less frequently exposed to an arc. By arranging the plate 4, the price increase of the arc extinguishing device 3 can be suppressed. Among the circuit breakers, the one in which the moving distance of the movable contact 2 during normal open / close operation and overcurrent interruption is different, the position of the movable contact 2 during normal opening and the movement during overcurrent interruption Since the arc extinguishing plate located between the positions of the contacts 2 is less frequently exposed to the arc, the effect of adopting the above configuration is particularly great.

[Brief description of drawings]

FIG. 1 is a plan view and a sectional view of a heat-resistant magnetic arc-extinguishing plate according to the present invention.

FIG. 2 is a sectional view of an arc extinguishing device in a circuit breaker according to the present invention.

FIG. 3 is a perspective view of a conventional arc extinguishing device for a circuit breaker.

FIG. 4 is a diagram illustrating a relationship between an arc extinguishing device and a contact, and an arc state.

[Explanation of symbols]

1 Fixed contact 2 Movable contact 3 Arc extinguishing device 4 Magnetic arc extinguishing plate 5 Ceramic arc extinguishing plate 6 Side plate 7 Heat-resistant magnetic arc extinguishing plate 7 ₁ Composite plating layer

Claims (3)

[Claims] 1. A pair of contacts which are arranged opposite to each other and which can be freely opened and closed, an arc generated between the opening and closing paths of the contacts intersects with a main plane thereof, and the open space of the contacts is surrounded by a U-shaped groove. In a circuit breaker in which a plurality of arc-quenching plates made of a magnetic metal plate for dividing, cooling, and extinguishing are arranged in parallel, a composite plating layer in which ceramic is eutectoid is applied to the surface of the arc-quenching plate. Circuit breaker to do. 2. The circuit breaker according to claim 1, wherein the composite plated layer is a composite plated layer in which nickel plating is co-deposited with silicon carbide or boron nitride. 3. The arc-extinguishing plate of a portion of the plurality of arc-extinguishing plates, which is frequently exposed to an arc, is subjected to composite plating. Circuit breaker.