JPH0155523B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power switchgear, and particularly to an improvement of an arc box.

A conventional power switchgear is constructed as shown in FIGS. 1, 2, and 3.

In the figure, reference numeral 1 denotes an arc extinguishing arc box made of a heat-resistant material, in which a grid 2 and a commutation plate 3 made of magnetic metal are arranged and fixed in accordance with the number of phases of the electrical circuit to be opened and closed. 4 is a cross bar, 5 is a movable contact, 6 is a movable contact attached to both ends of the movable contact 5, 7 is a movable contact holder, 8
is a square window provided on the cross bar 4, and 9 is a contact spring. This contact spring 9 is compressed and inserted into the corner window 8 of the crossbar 4. 11 is a base made of an electrical insulator, 12 is a terminal fixed to the top of the base 11 with a screw, 13 is a U-shaped fixed contact screwed to the top surface of the terminal 12, and a fixed contact is mounted on the top surface. 14 is installed. 15 is an arc runner fixed to the fixed contact 13.

This movable contact is connected to a built-in well-known electromagnetic drive device via a crossbar 4.

Such contact mechanisms are provided symmetrically with respect to the A-A cross section, and are arranged corresponding to the number of phases of the electrical circuits that open and close in a direction perpendicular to the plane of the paper.

In such a power switchgear, when the fixed contact 14 and the movable contact 6 are opened, one end of the arc generated between the two contacts is transferred from the movable contact 6 to the commutation plate 3, while the other end is transferred to the fixed contact 14. Transfers from to Arkrunner 15. The other end of the transferred arc moves toward the end on the arc runner 15, and finally the arc is extinguished by the grid 2 between the vertical part of the arc runner 15 and the commutation plate 3 facing it. .

By the way, in the conventional power switchgear, the arc between the commutation plate 3 and the grid 2, between the grids 2 and 2, and between the grid 2 and the arc runner 15 is caused by the magnetic field created by the current flowing through the arc runner 15. The arc is driven to the ceiling of the arc box 1 as shown in FIG. 4, and stagnates at the ceiling until the current reaches zero. For this reason, if the overcurrent is repeatedly applied and then cut off, the degree of carbonization of the ceiling of the arc box 1 increases, and the creeping insulation resistance of this part decreases significantly, resulting in a disadvantage that the shearing cannot be cut.

Therefore, an object of the present invention is to provide a groove in the ceiling of the arc box 1 to reduce the degree of decrease in the creeping resistance of the ceiling of the arc box.

FIG. 5 is a block diagram showing an embodiment of the present invention. In the figure, 1, 2, and 3 are the same as those in FIG. Reference numeral 16 denotes a groove provided between the grids 2 in the arc box 1.

Now, when the power switchgear contacts, the arc generated between both contacts is transferred to the leg 17 of the commutation plate 3 and the arc runner 15, and then the arc is transferred to the arc runner 15.
is driven by the magnetic field created by the current flowing through it.

It moves on the leg 17 of the commutation plate 3 and the arc runner 15, and moves between the plate surface of the commutation plate 3 and the grid facing surface 19 of the arc runner 15, and as shown in FIG. The current reaches zero point at this ceiling.

However, in the present invention, arc box 1
Since a groove is provided between the grids 2 on the ceiling of the arc box 1, the arc does not touch the inner surface of the arc box 1, which is the part 1a, 1b, and 1c in FIG. The degree of carbonization in the portions 1a, 1b, and 1c of the arc box 1 can be significantly reduced.

Furthermore, the creepage distance between the grids 2 is increased compared to the conventional power switchgear shown in FIG. 2.

Therefore, by applying the present invention, it is possible to significantly suppress the decrease in the creepage resistance between the grids due to repeated failures, so it is possible to make it difficult for failure to occur during repeated failures. Become.

[Brief explanation of drawings]

Fig. 1 is a partial sectional view showing a conventional power switchgear, Fig. 2 is a configuration diagram showing the main parts of the device in Fig. 1,
Fig. 3a is a plan view showing the arc runner of Fig. 1;
FIG. 3b is a sectional view showing the AA cross section of FIG. 3a,
FIG. 4 is a configuration diagram for explaining the conventional drawbacks, and FIG. 5 is a perspective view showing an embodiment of the present invention. In the diagram, 1 is the arc box, 2 is the grid, and 3 is the arc box.
1 is a commutation plate, and 16 is a groove provided in the ceiling of the arc box 1. In the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. Commutation plate for transferring one end of the arc generated at the movable contact, grid for extinguishing the arc,
The arc box has an arc box to which the commutation plate and the grid are attached, and the commutation plate and the grid are attached to the ceiling of the arc box, and the arc box has a space between the grids on the ceiling of the arc box, and between the grid and the commutation plate. A power switchgear characterized in that a groove is provided in the.