JPS5828152A - Circuit breaker - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] This invention relates to a circuit breaker with improved current limiting performance and current interrupting performance. Conventionally, when closing, the current flowing through a conductor is in the same direction and in a nearly straight line. In circuit breakers arranged in the same direction, the magnetic force generated by the current is not strong, so arc driving or arc expansion is insufficient. This invention increases arc elongation and arc drive by increasing the driving force acting on the arc and controlling the position of the arc's legs by applying simple modifications to the fixed and movable conductors. This improves flow performance and blocking performance.

A conventional example will be explained with reference to figures.

Figures 1 and 2 show examples of conventional circuit breakers.

In the figure, (1) is an enclosure made of an insulator, (2) is a fixed conductor, (3) is a fixed contact that forms a fixed electrical contact with the fixed conductor (2), ( 4) is a movable contact, (5) is a movable conductor which together with the movable contact (4) constitutes a movable electrical contact (2), and (6) is an operating mechanism section for operating the movable conductor (5).

(7) is 9 arcs generated at contacts (3) and (4), (8
) is an arc extinguishing plate that extinguishes the arc (7).

Next, the operation will be explained.

If a fault current flows through the circuit breaker, the operation mechanism section (6)
operates, opening the movable conductor (5). Along with this operation, an arc (7) is generated between the contacts (3) and (4).

The arc (7) is driven by the magnetic force of the current flowing through the movable conductor (5) and the absorption force of the arc extinguishing plate (8), and moves in the direction of the arc extinguishing plate (8). K Contact. When the arc (7) comes into contact with the arc extinguishing plate (8), it is further elongated by magnetic attraction, and is extinguished by being cooled. Conventional circuit breakers generally operate as described above. Before explaining the present invention, some explanation will be given regarding the magnetic force exerted by the current flowing through a conductor. FIG. 2 shows the vicinity of the contact points in FIG. 1. Current work 1 flows from the cloth to the left of the fixed conductor (2) in the drawing, and similarly, current work 1 flows from the cloth to the movable conductor (5).
is flowing.

Now, the arc (7) that occurred between the contacts (3) and (4)
An electromagnetic repulsion force Fb is acting from the movable conductor (5). The direction of this force is in the direction shown by the arrow in the figure, and is away from the movable conductor (5) (To It becomes smaller as it approaches (2). On the other hand, an electromagnetic repulsive force Fa acts from the fixed conductor (2), and the direction and strength of the force (3)' exhibit characteristics completely opposite to those described above.

Therefore, the arc (7) receives a driving force toward the tip of the movable conductor (5) on the movable contact (4) side, and toward the movable conductor (5) on the fixed contact (3) lit. In this way, the arc (7) subjected to a force in the opposite direction has its positive column part elongated, so that the length of the arc (7) is also the distance at which the contact point (3) is opened. (4), the arc voltage did not increase significantly, and therefore the current limiting performance was not sufficient.

Therefore, in order to extend the arc (7) in the direction of the arc extinguishing plate (8) or to drive the arc (7),
It is necessary to reduce the force exerted on the arc (7) from the fixed conductor (2). In other words, the force of the electromagnetic repulsion Fa shown in FIG. 2 should be reduced.

Here, the general characteristics of the arc will be explained.

FIG. 3 shows a conductor aO having a spherical tip. When an arc (7) has its legs on the surface of such a spherical conductor, the arc (7) will occur in a direction perpendicular to the conductor surface where its legs are located. This is generally known as the paper jet phenomenon (4). In the figure, nine arcs (
7), the angles θ and α with the electrode surface are 90′.

Now, from an engineering perspective, it is known that the longer the arc voltage, the higher the voltage.

Therefore, if the shape of the conductor surface where the arc 2 is generated is appropriately devised, the length of the arc can be sufficiently extended and the arc voltage can be significantly increased.

Therefore, by specifying the shapes of the fixed conductor and the movable conductor, the present invention utilizes the above phenomenon to sufficiently extend the arc even if the opening distance of the movable conductor is short, resulting in a significantly high arc voltage. It is an object of the present invention to provide a circuit breaker that can obtain improved current limiting performance and breaking performance.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 4 shows the main parts of this invention, which are the contacts and the conductor near the contact fixing part. This is the opposing contact point (3)
, when arc X occurs in (4) and conductor (2).

This figure shows the state of each arc when arc Y occurs on the side surface of (5). As previously mentioned, the legs of the arc occur at right angles to the conductive metal surface on which the arc is occurring.

This means that the nine angle θ shown in the drawing is 906. As shown in Fig. 4, depending on the position of the legs of arcs X and Y, the opening distance, that is, the contact point (3),
Even if the distance (4) is short, if the arc can be made like Y in the figure, the length of the arc will be long, and therefore it will be possible to obtain a large arc voltage.

Next, the relative arrangement shape of the conductor and the contact point will be explained.

An example of a pair of electrical contacts is shown in FIGS. 5 and 6.

FIG. 5 shows conductors (2) and (5) having a larger cross section than contacts (3) and (4). Such a conductor (2)
, (5), the arc length is not sufficient as shown in the figure. Figure 6 shows the case where the cross section of the conductor (2), (5) is small compared to the contacts (3), (4). show. In this case, it is clear from experiments and experience that it is difficult for the arc to move to the side surface of the conductor as described above. From this, as shown in Figure 4, a structure in which the cross-sectional size of the conductor parallel to the contact surface is the same as that of the contact, and the center axis of the conductor is perpendicular to the contact, allows the arc to move to the conductor surface. It can be seen that this is the most suitable contactor structure that is easy to use and has a high arc voltage.

FIG. 7 shows an example of a pair of electrical contacts of the present invention.

In the figure, a fixed conductor (2) and a movable conductor (5)
The contact mounting part (to) has the same cross section as the contacts (3) and (4), and the center axis 011 is perpendicular to the respective contacts (3) and (4) (θ=90'). and(
5a) is provided.

FIGS. 8(A) and 8(CB) are examples of circuit breakers incorporating fixed and movable conductors (2) and (5) having the above structure.

The shield operation is almost the same as the conventional example.

While the opening distance is short, an arc (7) occurs between the contacts (3) and (4) as shown in figure CB), but when the opening progresses to a certain extent, as shown in figure CB), an arc (7) occurs between the movable conductor ( The arc (7) is driven by the electromagnetic repulsion of the current flowing through the base 61 of 5) and the attractive force of the arc extinguishing plate (8), and the arc (7) is driven by the electromagnetic repulsion of the current flowing through the base 61 of 5) and the attraction of the arc extinguishing plate (8). It moves to the side and becomes a long arc (7) as shown in the figure. Therefore, the arc voltage increases significantly, the current limiting ability improves, and the rounding and breaking performance, which extends long enough to make sufficient contact with the arc extinguishing plate (8), also significantly improves.

As described above, according to the present invention, a circuit breaker with a simple structure and excellent current-limiting performance and breaking performance can be realized.

[Brief explanation of the drawing]

FIG. 1(A) is a plan sectional view showing a conventional circuit breaker;
Figure 0) is a cross-sectional view on the slope 0B-B line, Figure 2 is an explanatory diagram of the force acting on the arc, Figure vg3 is an explanatory diagram of the general characteristics of the arc, and Figure 4 is a circuit breaker according to the present invention. 5 and 6 are explanatory diagrams of the relative arrangement relationship between the conductor and the contact, and FIG. 7 is a side view showing an example of a pair of electric contacts of the present invention, FIGS. 8(6) and 8(b) are explanatory diagrams of the operation of a circuit breaker incorporating the electric contact of the present invention. (2) Fixed conductor, Q fixed contact mounting portion, (
3)... Fixed contact, (4)... Movable contact, (5)...
...Movable conductor, 6!9...Movable contact mounting part, (7)
... Arc, (8) ... Arc extinguishing plate, (1), ■ ... Electric contact, 01,0! ...Central axis. Note that the same reference numerals in the figures indicate the same or corresponding parts. Agent Makoto Kuzuno - (1 other person) ', 1 Figure (A) (B) To Figure 21 Figure 3 Artificial Law No. 7V

Claims (2)

[Claims] (1) In a pair of electrical contacts, each consisting of a conductor and a contact fixed to the conductor, contact mounting portions are formed on both conductors so that the central axis is perpendicular to the surface of the contact. A circuit breaker characterized in that the cross-sectional size of the conductor of each contact mounting portion parallel to the contact surface is set to be the same size as each contact. (2) The circuit breaker according to claim 1, which has an arc extinguishing plate for extinguishing an arc.