JPH0126139B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power switchgear, and more particularly to an improvement in a power switchgear that extinguishes an arc by using fluid pressurized by an arc generated when a current is interrupted.

Figure 1 is a cross-sectional view showing the state of a conventional switch of this type (hereinafter referred to as the "auto-puffer type") when the current begins to fade, and Figure 2 shows the state near the end of the arc. FIG. In the figure,
1 is a fixed terminal plate; 2 is a metal outer cylinder having one end fixed to the fixed terminal plate 1 and having a required opening 2a at the other end; 3 is a metal outer cylinder 2 with a spring 4 attached to the inner periphery of the opening 2a; A movable contact 5 is driven in the direction of the arrow X by a drive device (not shown) to separate from the fixed contact 3, and is driven in the opposite direction to contact the fixed contact 3. Reference numeral 6 denotes a nozzle made of an insulator fixed to the opening 2a of the metal outer cylinder 2. The center through hole 6a has an inner diameter that allows the movable contact 5 to slide inside the nozzle. It has a tapered portion 6c that widens toward the open end 6b on the protruding side from 2. Reference numeral 7 denotes a gas storage chamber enclosed in a metal outer cylinder 2, which communicates through the center through hole 6a of the nozzle 6 to the inside of a container (not shown) which encloses all the illustrated structural members and seals an arc-extinguishing gas inside. ing. Reference numeral 8 indicates an arc generated when the movable contact 5 dissociates from the fixed contact 3, and 9 indicates high-temperature arced gas generated by the arc 8 and enters the gas storage chamber 7.

When this switch is in the closed state, the movable contact 5 is in contact with the inner wall of the center through hole 6a of the nozzle 6.
The gas storage chamber 7 is in contact with the fixed contact 3, thereby forming a closed space. The spring 4 is for pressing the fixed contact 3 against the outer periphery of the movable contact 5. For this purpose, the fixed contact 3 is not a solid annular body, but is made of several Needless to say, it must be divided into small pieces and the small pieces must be arranged in a ring.

Next, when the movable contact 5 of the closed and energized switch is driven to dissociate it from the fixed contact 3 as described above, an arc 8 is generated between the two, and the contact with this high-temperature arc occurs. The gas in the vicinity is heated and expanded to become high-temperature arced gas 9, which enters into the gas storage chamber 7 and increases its internal pressure. When the movable contact 5 is further driven to the left in the figure and the opening between the tip end surface of the movable contact 5 and the tapered part 6c of the nozzle 6 becomes larger as shown in FIG. During this period, the high pressure gas in the arc 7 is rapidly discharged from the arc 8, and the arc 8 is cooled by this gas flow. When the alternating current reaches its zero point while the arc 8 is being cooled, the current is suddenly cut off.

By the way, in this conventional switch, the high-temperature arced gas 9 generated by the arc 8 at the initial stage of current interruption enters into the gas storage chamber 7 as shown in FIG. Since there is no way to mix it with gas, it invades by forcing low-temperature gas deep inside. Then, from the gap formed between the tip end surface of the movable contactor 5 and the tapered part 6c of the nozzle 6, the stage is reached where the high pressure gas in the gas storage chamber 7 is discharged to cool the arc 8. However, as shown in Fig. 2, most of the discharged gas is the high-temperature arced gas 9 as it is, and the cooling effect of the arc 8 is insufficient, resulting in poor shearing performance, especially when the current to be cut is large. There was a time when enough was enough.

This invention was made in view of the above-mentioned points, and involves making the high-temperature arced gas that has entered the gas storage chamber flow through it, thereby drawing in the low-temperature gas that was inside the gas storage chamber through the suction port, and mixing both gases. The purpose of the present invention is to provide a power switchgear which increases the arc cooling effect and has good current cutting performance by providing an ejector device that allows the arc to cool.

FIG. 3 is a cross-sectional view showing the configuration of an embodiment of the present invention, in which parts equivalent to those of the prior art described above are designated by the same reference numerals, and their explanation will be omitted. The present invention is completely the same as the conventional example except for the provision of an ejector device 10 for mixing the high temperature arced gas entering the gas storage chamber 7 with the low temperature gas present in the gas storage chamber 7 as shown in the figure. This ejector device 10 has an inlet opening that opens toward the arc generation site of the opening 2a of the outer cylinder 2 of the gas storage chamber 7, and the other end that opens toward the inner part of the gas storage chamber 7. A suction port is provided on the side wall. Therefore, the high-temperature arced gas generated by the arc 8 generated in the opening 2a flows through the ejector device 10 at high speed as shown by arrow A in the figure. This is because the current of the arc 8 flows in the axial direction, and the magnetic field caused by this current exerts a pinch force on the conductive arced gas flow, allowing the arced gas flowing into the ejector device 10 to efficiently flow through the center. That's why. Then, due to the well-known ejector effect, the low-temperature gas in the gas storage chamber 7 is sucked from the suction port as shown by arrow B in the figure and mixed with the high-temperature arced gas, thereby lowering the temperature of the high-temperature arced gas. After that, when the current decreases in the direction of the current zero point, the pressure of the arc 8 decreases, and the gas in the gas storage chamber 7 is sent out toward the arc 8, the gas whose temperature has decreased is sent out. The arc 8 is effectively cooled and the current is reliably interrupted.

FIG. 4 is a cross-sectional view showing the configuration of another embodiment of the present invention, in which an ejector device 11 used in this embodiment is shown.
The suction port is provided at a plurality of locations in the axial direction to increase the ejector effect, and its operation and effect are as described for the embodiment shown in FIG.

Although the auto-puffer type switch using arc-extinguishing gas has been described above as an example, the present invention is generally applicable to other types of power switchgear using arc-extinguishing fluid.

As detailed above, in the power switchgear of the present invention, an ejector device is provided in a fluid storage chamber that temporarily stores high-temperature fluid generated when an arc occurs, and the ejector device is installed in a fluid storage chamber that temporarily stores the high-temperature fluid and the fluid that already exists in the fluid storage chamber. Since it is mixed with low temperature fluid,
When the arc pressure decreases, a relatively low temperature fluid is blown onto the arc, and the arc is sufficiently cooled, so that the current cutting ability can be improved.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view showing the state of a conventional switch at the point when the current begins to fade, Fig. 2 is a cross-sectional view showing the state near the end of the extinguishing of the current, and Fig. 3 is an embodiment of the present invention. FIG. 4 is a sectional view showing the structure of another embodiment of the present invention. In the figure, 2 is a metal outer cylinder, 2a is its opening,
3 is a fixed contact, 5 is a movable contact, 7 is a fluid storage chamber, 8 is an arc, 9 is a high temperature and high pressure fluid, 10, 11
is an ejector device. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] 1. A metal outer cylinder disposed in an arc-extinguishing fluid and having an opening at only one end and a fluid storage chamber formed inside; a fixed contact, and a movable contact that is driven from outside along the axis of the metal outer cylinder so as to contact and dissociate from the fixed contact; The movable contact is brought into contact with the fixed contact to close an electric circuit, and the high temperature and high pressure fluid generated by the arc generated when the movable contact is dissociated from the fixed contact is temporarily stored in the fluid storage chamber. When the pressure decreases, high-pressure fluid in the fluid storage chamber is sprayed onto the arc to extinguish the arc and cut off the current in the electric circuit, in which the high-temperature, high-pressure fluid generated when the arc occurs flows through it. A power switching device characterized in that an ejector device is provided in the fluid storage chamber for sucking a low-temperature fluid present in the fluid storage chamber from a suction port and mixing the two fluids. 2. The power switching device according to claim 1, wherein the ejector device is provided with suction ports at a plurality of locations in the axial direction thereof.