JP2585421B2 - Circuit breaker - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit breaker having a magnetic shielding plate capable of preventing the influence of an electromagnetic force generated between poles when a short circuit is interrupted.

[Conventional technology]

The conventional device is described in Japanese Patent Application Laid-Open No. 57-57437,
In the case of using a thermal element with a bimetal as the overcurrent element, a flat heat absorbing member is provided between the poles, and the heat generated by the arc at the time of interruption is effectively transmitted to the low-temperature part to improve the performance and life. It was configured as shown. The above-mentioned conventional device does not have the oil dash pot relay portion, and does not consider the magnetic force when a large current flows during a short circuit.

[Problems to be solved by the invention]

The above prior art does not consider the effect of electromagnetic force generated between the current coils provided in each phase when a short circuit is interrupted, and when the circuit breaker becomes small and the pitch between phases becomes narrow, There has been a problem that the yoke is deformed by the electromagnetic force generated between the current coils, and the oil dash pot relay section is bent.

An object of the present invention is to absorb electromagnetic force generated between each other,
An object of the present invention is to constitute an electromagnetic barrier and to eliminate the magnetic influence of other phases and to eliminate deformation and the like.

[Means for solving the problem]

In order to achieve the above object, a magnetic absorbing plate for absorbing a magnetic force generated when a short-circuit current flows is disposed between the poles of a circuit breaker.

The magnetic absorbing plate is disposed at a position covering the entire oil dash pot relay portion in a U-shape, and further increases the strength against gas pressure at the time of short circuit.

Further, by forming the magnetic absorber insulated in the mold case, the specific gravity of the magnetic absorber is increased, which leads to an increase in heat volume and an increase in temperature margin.

[Action]

The oil dash pot relay portion is provided with a cylinder having a plunger inside at the center, and also has a brake oil in the cylinder which performs a time-delay characteristic when the plunger rises due to an increasing electromagnetic force. Has a return spring that returns to its original position when it is located at the top. Further, the cylinder has one end sealed with a cap. A current coil is provided around the cylinder, and always supplies a magnetic force when energized. The magnitude of this electromagnetic force changes depending on the magnitude of the current flowing through the current coil, and the plunger, yoke, movable core,
Occurs in the path through the cap. With respect to a minute overcurrent of 125, 200%, etc., the plunger rises and reaches the cap to increase the magnetic force, and the movable core is attracted to make the mechanism part trip.

When a large current such as a short circuit accident flows through the current coil,
Even without the operation of the plunger, the movable iron piece can be sucked and tripped with the mechanism. The magnetic force generated at the time of this short circuit affects the adjacent current coil. In order to eliminate the influence of this magnetic force on the other pole, a magnetic shielding plate is provided between the poles. The shielding plate is inserted from the bottom of the mold case, and is inserted into a U-shaped groove provided in the mold case in advance. One magnetic shielding plate is provided for each pole. The magnetic shield plate inserted into the case is prevented from dropping to the lower part of the mold case by the bottom plate.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to FIGS. A first embodiment of the present invention will be described with reference to FIGS. In the case where the oil dash pot relay is used for the overcurrent detection part of the circuit breaker, the plunger 5 of the oil dash pot relay 24
Rises in the direction of the cap 6 by the increased magnetic force, and when the plunger 5 reaches the cap 6, the magnetic force increases rapidly and the movable core 9 is attracted. This movement is transmitted to the opening / closing mechanism section via the tripping mechanism 22, and the opening / closing mechanism section 20 operates to cause the movable contact table 15 to perform the opening operation. When a large current, such as a short-circuit current, flows through the current coil 4, the current value is extremely large, so that even when the plunger 5 is not lifted, the movable core 9 can be attracted and the electrode can be opened. In this embodiment, as shown in FIG. 1A, a current coil 4 and a yoke are provided in a molded case 1 below an oil dash pot relay portion.
A magnetic shield plate 3 is formed so as to surround the coil 10 and a magnetic force is generated by the current coil 4 when a short-circuit current 4 'flows. In the present embodiment, the magnetic force generated as shown in FIG. 3 is absorbed by the shield plate 3 as a path by having the magnetic shield plate provided so as to surround the current coil 4, and the magnetic influence on the other adjacent pole is obtained. Can be eliminated.

FIG. 1B is a plan view of the oil dash pot relay and the magnetic shield plate 3 as viewed from above, and FIG. 2 is a perspective view showing the position of the magnetic shield plate 3 in the mold case 1. FIG. 4 is a sectional view showing the overall configuration of the present embodiment.

In the present embodiment, the oil dash pot relay is inserted into the mold case 1 from above, and the magnetic shielding plate 3 is inserted from below (back surface) of the mold case 1 for each pole. Since the magnetic shielding plate 3 is both a magnetic material and a conductor, it is insulated from the oil dash pot relay by the resin of the mold case 1. After the insertion of the magnetic shielding plate 3, a cover 11 is attached to the back surface of the mold case 1 to prevent the magnetic shielding plate 3 from falling off. For comparison, a phenomenon at the time of a short circuit when there is no magnetic shielding plate will be described.

If the magnetic shield plate is bad, as shown in FIG. 8, when an interphase short circuit occurs in the two-pole breaker, a magnetic force is generated around the current coil by a large current generated at the time of the short circuit. In addition, a short-circuit current similarly flows in the adjacent pole. At this time, the poles adjacent to each other have the same direction of the current flowing through the current coil.
A force acts in the direction of suction. This pulls the cylinder 7 assembly located inside the current coil, deforming the yoke 10 positioning it. At this time, the mutual attraction force is inversely proportional to the square of the mutual distance of the current coils 4, and is proportional to the square of the magnitude of the current. Therefore, in order to reduce the size of the circuit breaker and increase the breaking capacity, the pitch between the poles is reduced, the distance between the current coils 4 is reduced, and the magnitude of the current is increased. The magnetic force increases. If the yoke 10 is reinforced to cope with this, the yoke 10 becomes large and cannot be mounted due to a storage space problem.

 A second embodiment of the present invention will be described with reference to FIGS.

In the present embodiment, a flat magnetic shielding plate 3a is inserted between adjacent poles. In this embodiment, the magnetic shielding plate 3a is provided so as to be inserted into a groove provided in a partition wall between the mold case 1 and the cover 3 between the poles. In this embodiment, the magnetic shielding plate
3a can be mounted in the mold case 1 from the same direction as other components such as an oil dash pot relay, which is suitable for automation of production. FIG. 5A is a sectional view of a main part of the present embodiment,
FIG. 5B is a plan view of a main part of this embodiment.

A third embodiment of the present invention will be described with reference to FIGS. 6A, 6B and 7. FIG. This embodiment has a magnetic shielding effect.
The shield portion 10a is provided in a part of the yoke, especially in a part located between the poles. With this, together with the magnetic shielding effect when a large current flows, the leakage magnetism of the oil dash pot relay part is also gathered by increasing the path and increasing the magnetic force against the slight overcurrent operation be able to.

6A and 6B are a cross-sectional view and a plan view, respectively, of a main part of the present embodiment, and FIGS. 7A and B are perspective views of a yoke of the oil dash pot of the present embodiment and a coil incorporated therein. FIG.

〔The invention's effect〕

 According to the present invention, the following effects can be obtained.

1. When a large current such as a short-circuit current flows, the magnetic force generated in the current coil eliminates the deformation of the yoke and the bending of the cylinder assembly, and has a highly reliable overcurrent detector.

2. By positioning the magnetic shielding plate inside the mold case, it is not necessary to increase the mounting space.

3. Since the magnetic shielding plate is inserted into the mold case in a U-shape, the mold strength against the gas pressure at the time of shutoff can be increased.

4. The heat volume can be increased by the density (specific gravity) of the magnetic shielding plate, and the temperature effect is reduced.

5. According to FIG. 6 of the alternative, there is a magnetic shielding effect without increasing the number of parts, and further, the magnetic characteristics against a slight overcurrent can be improved, and the plunger attraction force can be increased.

[Brief description of the drawings]

1A and 1B are a longitudinal sectional view and a plan view, respectively, showing a main part of a circuit breaker according to a first embodiment of the present invention. FIG. 2 is a perspective view showing a configuration of a magnetic shielding plate according to the present embodiment. 3 is a plan view showing the state of current and lines of magnetic force in this embodiment, FIG. 4 is a longitudinal sectional view showing the entire configuration of this embodiment, and FIGS.
6 is a longitudinal sectional view and a plan view, respectively, showing a main part of a circuit breaker according to a second embodiment of the present invention. FIGS. 6A and 6B are vertical cross-sectional views showing main parts of a circuit breaker according to a third embodiment of the present invention. 7A and 7B are perspective views of a yoke of an oil dash pot and a perspective view of a state in which a coil is incorporated in the present embodiment, respectively. FIG. FIG. 3 is a plan view showing the state of magnetic field lines. 1: Mold case, 2: Cover, 3, 3a, 10a: Magnetic shielding plate,
4: current coil, 14: fixed contact, 15: movable contact, 20: opening / closing mechanism, 22: tripping mechanism, 24: oil dash pot relay.

Claims (2)

(57) [Claims] 1. An oil dash pot relay having a current coil in a mold case and provided for each phase, an opening / closing mechanism for opening and closing a movable contact by operation of the oil pot relay, and the movable contact And a cover surrounding the oil dashpot relay, the movable contact, the opening / closing mechanism, and the fixed contact. A circuit breaker having a magnetic shielding plate that absorbs an electromagnetic force generated by a current coil between poles when a short-circuit current flows between the poles. 2. The circuit breaker according to claim 1, wherein said magnetic shielding plate has a substantially U-shaped cross section, and a rising portion of said U-shape is provided adjacent to each pole.