JPH03230436A - Vacuum valve - Google Patents

Abstract

PURPOSE:To actuate current-limiting action in a low voltage system by providing an auxiliary electrode around a moving side electrode which is smaller than a fixed side electrode by a preset area, and by dividing and igniting a vacuum arc at the opening time. CONSTITUTION:The electrode area of a fixed side electrode 15 is formed larger than that of a moving side electrode 16 by a preset area, and when the electrodes 15, 16 are opened, due to a breaking current, the electrode 16 moves in openings 18 of plural auxiliary electrodes 17. A vacuum arc 21 moves to the side of the electrode 17, and begins to ignite, and the force that pushes in the directions indicated by arrows works on the arc 21. The arc 21 is forced in the electrode 17 thereby. The electrode 17 is divided and supported by an insulating support member 19, is insulated with one another, while the arc is divided and ignited by the electrode 17, plural arcs are ignited in series between the electrodes 15 and 16. The breaking current becomes of a small level, and there is a current-limiting action in a low voltage system with the electrodes 15, 16, and downsizing is thus possible.

Description

DETAILED DESCRIPTION OF THE INVENTION [Purpose of the Invention (Industrial Application Field) The present invention relates to a vacuum valve that is particularly used in low voltage systems and has excellent large current interrupting performance.

(Prior art) As a conventional vacuum valve, for example, the Japanese Patent Publication No. 54-228
The one disclosed in Publication No. 13 is known. As shown in FIG. 7, the structure of this vacuum valve is such that the openings at both ends of an insulating cylinder 1 are hermetically sealed with an end plate 2.3 to form a vacuum container 4, which can be freely moved in and out of the vacuum container 4. A pair of electrodes, a fixed side electrode 5 and a movable side electrode 6, are provided.

A fixed energizing shaft 7 of the fixed electrode 5 is fixedly attached to the end plate 2, and a movable energizing shaft 8 of the movable electrode 6 is movably attached to the end plate 3 via a bellows 9.

Reference numeral 10 denotes an arc shield, which is attached to the insulating cylinder 1 so as to surround the fixed electrode 5 and the movable electrode 6.

When interrupting current with a vacuum valve having such a configuration, the vacuum arc generated between the electrodes 5.6 at the time of interrupting the current generally has a low arc voltage and therefore rarely damages the electrodes 5.6. For this reason, such vacuum valves are often used for multiple current interruptions.

However, when the breaking current becomes large enough to exceed several tens of kA, it is necessary to use electrodes with a special structure.

On the other hand, there is a well-known method that uses vertical magnetic field electrodes (I E E E T transact
ionson Power Apparatus
and Systems Vol.

PAS-100, No. 4.1981. pp1966-
1973 “Novel E 1ectrode
Structure of Vacuum Inte
rrupter and Its Practical
at Application”) a However,
For devices that use this vertical magnetic field electrode, in order to cut off large currents exceeding several tens of kA, the diameter of the electrode must be quite large, and the vacuum valve must be quite large. For vacuum valves used in voltage systems, it is more rational to lower the interrupting duty of the vacuum valve by increasing the generated arc voltage to a level higher than the system voltage and limiting the interrupting current.

However, as mentioned above, in a vacuum arc, the arc voltage is low, so this current limiting effect cannot be expected.

However, since low arc voltage and minimal damage to the electrodes are desirable factors for improving product reliability, it is desired that the vacuum valve has a current limiting effect.

(Problem to be solved by the invention) In conventional vacuum valves, the arc voltage of the vacuum arc that occurs when the current is cut off is low, so current limiting action cannot be expected, and the breaking current becomes large, reaching several tens of kA. In order to cut off such a large current, even if the electrode has a special structure, the diameter of the electrode becomes quite large, resulting in a large vacuum valve.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a vacuum valve that does not require a particularly large electrode, can be constructed in a small size, can be used in a low-voltage system, and has an excellent current-limiting effect while maintaining high reliability. With the goal.

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above problems, the present invention provides a movable electrode and a fixed electrode having a required area larger than the movable electrode in a vacuum container. side electrodes are disposed facing each other so as to be able to come into contact with and separate from the movable side electrode, and a vacuum arc generated when the movable side electrode and the fixed side electrode are opened is ignited in a mutually insulated manner around the movable side electrode. The main feature is that a plurality of auxiliary electrodes are arranged.

Further, the present invention also includes forming a spiral groove in at least one of the movable side electrode and the fixed side electrode.

(Function) When the movable side electrode and the fixed side electrode are opened to interrupt current, a vacuum arc is generated between the electrodes. At this time, when the movable electrode moves between a plurality of mutually insulated auxiliary electrodes, the vacuum arc moves to the auxiliary electrode side and is ignited between each auxiliary electrode. In this way, when split ignition is performed using multiple auxiliary electrodes that are insulated from each other, vacuum arcs or multiple It becomes a situation where individual ignition occurs. The arc voltage of a vacuum arc is generally on the order of several tens of volts to 100 volts, so when a plurality of vacuum arcs are ignited in series, the total arc voltage reaches several hundreds of volts. Since this increased voltage corresponds to the grid voltage, the short circuit current value is limited to a small value. In this way, it is possible to achieve the effect of maintaining multiple shutoffs and high reliability while also having excellent current limiting performance.

Further, by forming the spiral groove in the electrode, a current path is formed in the electrode from the center toward the outer periphery. Then, an electromagnetic force from the center of the electrode toward the outer circumference acts on the vacuum arc generated between the two electrodes due to this current, and the vacuum arc rapidly heads toward the auxiliary electrode and is ignited in a dispersed manner. Thereby, the current limiting effect described above is performed more rapidly and reliably.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIGS. 1 and 2 are diagrams showing a first embodiment.

FIG. 1 is a longitudinal cross-sectional view showing the internal structure, and FIG. 2 is a diagram showing the state in the middle of current interruption with the movable side electrode moved.

In addition, in FIGS. 1, 2, and the figures showing each embodiment described later, the same or equivalent parts as those in FIG. do.

First, to explain the structure of the vacuum valve, the vacuum valve of this embodiment has a structure in which the electrode area of the fixed side electrode 15 is
It is formed to be larger than the electrode area of No. 6 by the required area. When the electrodes 15 and 16 are opened to cut off the current, the movable electrode 16 is connected to the opening 1 of the plurality of auxiliary electrodes 17.
It has a structure that moves within 8. Multiple auxiliary electrodes 1
7 are dividedly supported by an insulating support member 19 and insulated from each other.

Note that the plurality of auxiliary electrodes 17 may be divided and supported by a support member having an appropriate resistance value instead of the insulating support member 19, so that an appropriate resistance value exists between each auxiliary electrode 17.

When the picture electrode is opened to cut off the current, the vacuum electrode 21 is divided and fired for the plurality of auxiliary electrodes 17, and the movable side electrode 16
It is as if a plurality of vacuum arcs are ignited in series between the movable electrode 16 and the fixed electrode 15, which has a larger required area than the movable electrode 16.

Next, the operation of the vacuum valve configured as described above will be explained.

When a short circuit or ground fault occurs and an accidental current flows through the vacuum valve, and the movable electrode 16 is separated from the fixed electrode 15 by an operation mechanism (not shown), a cathode spot is formed on the electrode that has become a cathode. The vacuum arc 21 is generated in the space between the picture electrodes 15 and 16 by the metal vapor plasma generated thereby. To interrupt this current, electrode 15.
When the movable electrode 16 is separated, the vacuum arc 21 moves to the side of the auxiliary electrode 17 and starts ignition.

At this time, as shown in FIG. 2, a force is applied to each vacuum arc 21 that pushes the arc in the direction of the arrow, so as a result, the arc is pushed between each auxiliary electrode 17 and is ignited in series. become.

When the multiple auxiliary electrodes 17 are insulated from each other, the movable side electrode 16 and the movable side electrode 1
The fixed side electrode 15 has a larger required area and electrode area than 6.
During this period, a situation occurs as if a plurality of vacuum arcs 21 were ignited in series.

The arc voltage of a vacuum arc is generally about IOV to 100V, so if multiple arcs are ignited in series, the total arc voltage will be several tens of volts.
It even reaches 0V. Since this increased voltage corresponds to the grid voltage, it is limited to a short circuit fault current or a small value.

In this way, the vacuum valve of this embodiment can limit the interrupting current to a small value by using the plurality of auxiliary electrodes, so there is no need for particularly large electrodes on the fixed side and movable side, which is different from the conventional vacuum valve. Compared to a vacuum valve that uses a special electrode structure and has a large electrode diameter for interrupting large currents, the vacuum valve can be made smaller despite the addition of an auxiliary electrode.

Next, FIGS. 3 and 4 show a second embodiment. FIG. 3 is a vertical cross-sectional view showing the internal structure, and FIG. 4 shows the state in the middle of current interruption with the movable side electrode moved.

In this embodiment, a plurality of auxiliary electrodes 17 are supported separately on a part of the insulating cylinder 11 and are insulated from each other. The insulating cylinder 11 is a combination type in which only the supporting parts of the plurality of auxiliary electrodes 17 are made of an insulating material, and the auxiliary electrodes 17 are
You can check the assembly status of etc.

In the vacuum valve of this embodiment, since the insulating cylinder 11 also serves as a support member for the plurality of auxiliary electrodes 17, it has the advantage that the number of parts is reduced compared to that of the first embodiment.

As shown in FIG. 4, the current limiting effect of the breaking current and the like are almost the same as those of the first embodiment.

FIG. 5 shows a third embodiment.

In this embodiment, the insulating cylinder 12 has a single structure similar to that of the first embodiment, and a support part 12a is provided protrudingly from a part of the inside of the insulating cylinder 12. A plurality of auxiliary electrodes 17 are supported separately and insulated from each other.

As in the second embodiment, if only the support part of the auxiliary electrode 17 is made of a combined insulating cylinder made of an insulating material, the assembly status can be checked during manufacturing, which is a relatively desirable structure in terms of manufacturing technology. In other words, it is still not enough to reduce the number of parts.

In contrast, in this embodiment, the insulating cylinder 12, which also serves as a support member for the auxiliary electrode 17, has a single structure.
It is possible to reduce the number of layers and parts.

The current limiting effect of the breaking current, etc., is almost the same as that of the first embodiment.

FIG. 6 shows the main part of the fourth embodiment.

It is clear that in each of the embodiments described above, it is desirable that the current limiting action of the breaking current be performed at the instant when the fixed side electrode 15 and the movable side electrode 16 begin to separate. This fourth embodiment is designed to achieve this in a layer-effective manner, and the fixed side electrode] 5 is provided with spiral grooves 22 or a plurality of spiral grooves (
In the figure, 3) are formed.

Due to the formation of this groove 22, the current flowing in the electrode 15 flows along the current path 23, so that an electromagnetic force acts on the vacuum arc 21 between the electrodes 15 and 16 in the direction of the arrow in the figure, and it rapidly moves toward the auxiliary electrode 17 and points at the dispersion point. It will arc. Thereby, the above-mentioned current limiting effect is performed rapidly and reliably.

Note that the spiral groove may be formed in the movable side electrode] 6, or may be formed in the movable side and fixed side picture electrodes 15 and 16.

[Effects of the Invention] As explained above, according to the present invention, in the vacuum container,
A movable side electrode and a fixed side electrode having a required area larger than that of the movable side electrode are disposed facing each other so as to be able to come into contact with each other freely, and around the movable side electrode, the movable side electrode and the fixed side electrode are arranged to face each other. Since we have installed multiple mutually insulated auxiliary electrodes that are ignited separately, the vacuum arc that occurs when the picture electrode is opened is separated from the movable side electrode and the movable side electrode. However, the required area is larger than that of the fixed electrode, so it becomes as if multiple arcs are ignited in series, and the total arc voltage suddenly rises to a value equivalent to the grid voltage, causing a short circuit. It is possible to limit the current value to a small value. Therefore, there is no need for particularly large electrodes,
It has the advantage that it can be constructed compactly and can be used in low-voltage systems, and that it can obtain an excellent current limiting effect while maintaining high reliability.

In addition, by forming a spiral groove in at least one of the movable electrode and the fixed electrode, a current path is formed in the electrode from the center to the outer periphery. The vacuum arc generated by applying an electromagnetic force from the center of the electrode toward the outer circumference can be rapidly dispersed and ignited to the auxiliary electrode. Therefore, the above-mentioned current limiting effect can be performed more rapidly and reliably.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view showing a first embodiment of the vacuum valve according to the present invention, FIG. 2 is a vertical cross-sectional view for explaining the operation of the first embodiment, and FIG. FIG. 4 is a longitudinal sectional view showing the operation of the second embodiment, FIG. 5 is a longitudinal sectional view showing the third embodiment of the present invention,
FIG. 6 is a perspective view showing the main parts of the fourth embodiment of the present invention, and FIG.
The figure is a longitudinal sectional view showing a conventional vacuum valve. 4: Vacuum container, 11: Insulating cylinder that also serves as a support member for the auxiliary electrode, 12a:
Support part of auxiliary electrode, 15: fixed side electrode, 16: movable side electrode, 17: auxiliary electrode, 18: opening, 19: insulating support member, 22: spiral groove.

Claims (2)

[Claims] (1) A movable side electrode and a fixed side electrode having an electrode area larger than that of the movable side electrode by a required area are arranged facing each other in a vacuum container so as to be able to freely come and go, and around the movable side electrode, A vacuum valve characterized in that a plurality of mutually insulated auxiliary electrodes are arranged to separately ignite a vacuum arc generated when the movable side electrode and the fixed side electrode are opened. (2) The vacuum valve according to claim 1, wherein a spiral groove is formed in at least one of the movable side electrode and the fixed side electrode.