JP3344180B2 - Circuit breaker - Google Patents

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 improved arc resistance.

[0002]

2. Description of the Related Art FIG.
No. 8 is a perspective view of an arc extinguishing device in a conventional circuit breaker, and FIG. 4 is a diagram illustrating a relationship between the arc extinguishing device and a contact. 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 at the center thereof. And fixed to the insulating side plate 6. The heat-resistant arc extinguishing plate 5 is made of a ceramic plate formed substantially in the same shape as the magnetic arc extinguishing plate 4, and is bonded to the magnetic arc extinguishing plate 4.

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

[0004]

In the conventional arc extinguishing device for a circuit breaker as described above, since the magnetic arc extinguishing plate 4 and the ceramic arc extinguishing plate 5 are bonded together, the U of the magnetic arc extinguishing plate 4 is reduced. The cross section of the U-shaped groove exposes the magnetic metal. Since the exposed portion is closest to the arc and may be melted by contact with the arc, it is necessary to increase the width of the U-shaped groove, and it has been difficult to reduce the size of 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 also becomes an obstacle when the arc gas moves into the arc extinguishing device. To solve this problem, the arc extinguishing device may be increased in size, but there is a problem that the circuit breaker is further enlarged. On the other hand, when the number of the magnetic arc extinguishing plates 4 is reduced, the cross-sectional area of the magnetic path is reduced, so that the driving force of the arc is reduced, and there is a problem that the arc-separating arc extinguishing effect is reduced.

The present invention has been made to solve such a problem, and is resistant to arc heat at the time of current interruption.
An object of the present invention is to realize a small-sized circuit breaker having excellent breaking performance and durability.

[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 eutectoid.

Further, the composite plating is obtained by eutecting silicon carbide or boron nitride on nickel plating.

In addition, the composite plating is applied only to the arc-extinguishing plate at a portion where the frequency of exposure to the arc is high.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. FIG. 1 shows a heat-resistant magnetic arc-extinguishing plate of a circuit breaker according to the present invention. In the figure, reference numeral 7 denotes a heat-resistant magnetic arc-extinguishing plate subjected to a composite plating process, and a magnetic metal plate 7 ₁
The surface of is formed with composite plating layer 7 _2. Composite plating layer 7 ₂ is obtained by eutectoid in an electroless nickel plating solution to silicon carbide or ceramic particles such as boron nitride is dispersed in the magnetic metal plate ₇₁ surface. Silicon carbide has a sublimation temperature of 2200 ° C. and a melting point of 2700 ° C. or higher, and boron nitride has a sublimation point of 3000 ° C. under normal pressure and a melting point of 30 under high pressure.
Since a 00 ° C., the composite plating layer 7 ₂ withstand high temperatures due to the arc. Composite plating layer 7 ₂ can exhibit sufficient effects at a thickness of 10μm approximately, heat magnetic extinguishing plate 7 because it requires a thickness of substantially magnetic metal plate _71, it is possible to a large number of sheets arranged. Further, since the heat magnetic extinguishing plate 7 can form a composite plating layer 7 ₂ easily even in a U-shaped groove inner surface, U
The groove width of the U-shaped groove can be reduced, and the arc extinguishing device 3 can be reduced in size. Incidentally, the composite plating layer ₇₁ is not limited to the above configuration, excellent metal and it may be a ceramic combination course in heat resistance without impairing arc extinguishing performance.

FIG. 2 is a sectional view of an arc extinguishing device of a circuit breaker to which the heat-resistant magnetic arc extinguishing plate according to the present invention is applied, and the same or corresponding parts as those in FIGS. 3 and 4 are denoted 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 a composite plating process is disposed in a portion that is frequently exposed to the arc, and a magnetic arc-extinguishing plate that is not subjected to the composite plating process is disposed in a portion that is not frequently exposed to the arc. By arranging the plate 4, an increase in the price of the arc extinguishing device 3 can be suppressed. Among the circuit breakers, those in which the moving distance of the movable contact 2 at the time of normal open / close operation and the overcurrent interruption are different from each other, the position of the movable contact 2 at the time of normal opening and the movable at the time of overcurrent interruption. Since the arc-extinguishing plate located between the positions of the contacts 2 is rarely exposed to the arc, the effect of adopting the above configuration is particularly large.

[Brief description of the 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 cross-sectional view of the arc extinguishing device in the 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 point and an arc state.

[Explanation of symbols]

Reference Signs List 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

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-56-167227 (JP, A) JP-A-58-157010 (JP, A) JP-A-52-54970 (JP, A) JP-A-4- 126314 (JP, A) JP-A-6-103855 (JP, A) JP-A-7-45162 (JP, A) JP-A 8-129949 (JP, A) Japanese Utility Model Publication No. 57-194238 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) H01H 73/18 H01H 9/36

Claims (3)

(57) [Claims] 1. A pair of openable and closable contacts arranged opposite to each other, an arc generated between the open / close paths of the contacts, and a main plane thereof intersecting, and the open space of the contacts is surrounded by a U-shaped groove to form the arc. In a circuit breaker in which a plurality of arc extinguishing plates made of a magnetic metal plate for dividing, cooling, and extinguishing are arranged in parallel, a composite plating layer made of eutectoid ceramic is applied to the surface of the arc extinguishing plate. Circuit breaker to do. 2. The circuit breaker according to claim 1, wherein the composite plating layer is a composite plating layer in which silicon carbide or boron nitride is codeposited on nickel plating. 3. The arc-extinguishing plate of a portion of the plurality of arc-extinguishing plates that is frequently exposed to an arc is subjected to composite plating. Circuit breaker.