JPH07220587A - Vacuum valve - Google Patents

Abstract

PURPOSE:To provide a vacuum valve having excellent energization performance and disconnection performance. CONSTITUTION:For a pair of electrodes disposed facing each other to get closer to/apart from each other in a vacuum container, a movable electrode 3B, for example, is formed into a cylindrical form in which grooves 6A, 6B are formed to generate an axial magnetic field between the electrodes. An insertion part having an energization part 7A, 7B and an insulation part 8 is provided between this electrode 3B and a contact 4B.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum valve having excellent energizing performance and breaking performance.

[0002]

2. Description of the Related Art FIG. 3 is a vertical sectional view of a typical vacuum valve incorporated in a vacuum circuit breaker, and FIG. 4 is a sectional view taken along line BB of FIG. As shown in FIGS. 3 and 4, this vacuum valve is arranged so that the fixed electrode 13A and the movable electrode 13B can be contacted and separated from each other in a vacuum container in which both ends of the insulating cylinder 1 are sealed by the fixed flange 2A and the movable flange 2B. Has been done.

Of these, the fixed electrode 13A is fixed to the tip of a fixed current-carrying shaft 5A which penetrates the fixed flange 2A, and a contactor 4A is coupled to the front surface of the fixed electrode 13A so as to be fixed to the outside of the vacuum vessel. It is connected by a shaft 5A. on the other hand,
The movable electrode 13B is a guide tube penetrating the movable flange 2B.
It is fixed to the tip of the movable energizing shaft 5B penetrating 10 and the contactor 4B is coupled to the front surface of the movable electrode 13B, and is connected to the outside of the vacuum container by the movable energizing shaft 5B. The intermediate portion of the movable energizing shaft 5B is supported by the movable flange 2B via the bellows cover 15 and the bellows 9. In this way, while maintaining the vacuum in the vacuum container, it is possible to energize and interrupt the energization by contact and separation with the fixed electrode 13A by the operating mechanism section (not shown) via the insulating rod connected to the lower end of the movable energizing shaft 5B. . A cylindrical arc shield 14 is attached to the inner surface of the insulating cylinder 1.

By the way, since the vacuum valve utilizes the excellent dielectric strength of vacuum, the distance between the electrodes can be shortened as compared with, for example, an SF ₆ gas circuit breaker using another insulating medium, and the outer shape can be reduced. Can be made small. Also, the breaking capacity can be increased by changing the configuration of the electrodes. On the other hand, in order to improve the breaking performance of the vacuum valve, it is necessary to suppress the local heating of the electrodes due to the arc generated between the electrodes. That is, the blocking performance can be improved by suppressing the generation of abnormal charged particles and the generation of metal vapor due to local heating of the electrode. The electrode structure for this is as follows:
A method of applying an electromagnetic force with a magnetic field is common.

As one of the methods of applying a magnetic field, there is a method of applying a perpendicular magnetic field to an arc generated between electrodes. The electrodes using this method include spiral electrodes,
There is also what is called a contact electrode, and the magnetic field generated in such an electrode is a magnetic field radial from the axial center of the electrode. Therefore, since the magnetic field is orthogonal to the arc generated between the electrodes, Lorentz force acts on the arc in the circumferential direction. As a result, the arc is rotationally driven in the circumferential direction, and by moving the electrode surface, it is possible to prevent the aforementioned generation of particles and vapor due to local melting of the electrode due to local heat input.

However, in a vacuum valve incorporated in a vacuum circuit breaker applied to a high voltage circuit, it is necessary to increase the distance between the electrodes in order to increase the withstand voltage value between the electrodes.
In the above electrode structure in which a magnetic field perpendicular to the arc generated between the electrodes is applied, when the arc rotates on the surface of the electrode, the arc may be stretched in the circumferential direction and may be radially ejected from the electrode. At this time, there is a risk that the arc will ignite the arc shield mounted around the electrodes.If the arc ignites on the arc shield, the arc will stagnate at the igniting part and locally excessive heat input will occur. Occurs. If the electrode and the arc shield are melted by this excessive heat input, the breaking performance is deteriorated. Further, in this electrode structure, as described above, since the arc state is a concentrated arc and the temperature is high, the wear of the contacts is accelerated, and the switching life at the time of large current interruption is shortened.

On the other hand, as another method of applying a magnetic field to the arc generated when the current is cut off, there is a method of applying a magnetic field in the axial direction parallel to the arc generated between the electrodes. This electrode, which is called the so-called longitudinal magnetic field electrode,
The arc generated between the electrodes spreads evenly across the electrodes,
It is possible to prevent an excessive local heat input to the electrode and provide an electrode having excellent blocking performance. Moreover, even when the distance between the electrodes is increased with respect to the high voltage, a stable arc can be ignited between the electrodes by optimizing the strength of the magnetic field.
The blocking performance can be improved. Further, since the arc form is an arc dispersed over the entire electrode, even when a large current is interrupted, the contact wear is small and the switching life can be extended.

Now, the electrode structure of a vacuum valve that generates a typical axial magnetic field will be described. As shown in FIG. 4, a coil electrode is provided, and an electric field flowing in the coil electrode generates an axial magnetic field between the electrodes. The current flowing in this coil electrode is shunted into four arms 13a formed radially from the center, flows from the tip of each arm 13a to the arc-shaped coil 13b, and further contacts from the tip 13c of the coil. It flows to the child. This coil electrode is attached to both the movable electrode side and the fixed electrode side, and a magnetic field in the axial direction is generated between the electrodes by the current flowing in the coil portion. Although FIG. 4 shows the case where the arm portion 13a is divided into four, the number of divisions can be changed to change the strength of the magnetic field in the axial direction.

Another electrode structure for generating a magnetic field in the axial direction is, for example, as shown in Japanese Patent Publication No. 3-59531, in which a spiral groove is formed in the cylindrical portion of a cup-shaped electrode. In this electrode, by making the current path of the cylindrical portion spiral, an arc-shaped component of the current is generated, thereby generating a magnetic field in the axial direction between the electrodes. With this configuration, the strength of the magnetic field in the axial direction can be changed by changing the inclination of the groove of the cylindrical portion.

[0010]

In recent years, a vacuum circuit breaker using a vacuum valve has been widely used, and accordingly, not only the breaking performance but also the energizing capacity of a normal load is desired to be increased. There is. This is because the short-circuit capacity of the system has increased with the increase in the capacity of general consumers, which is the load when configuring the system. In order to increase the breaking performance, improvements have been made in the electrode structure and contact material, but in order to improve the current carrying capacity, it is necessary to reduce the resistance between terminals of the vacuum valve.

The resistance value of the vacuum valve is the sum of the contact resistances of the current-carrying shaft portion, the electrode portion, and the contact. Copper is generally used for the current-carrying shaft and has low resistance. Even if the shaft diameter is increased, the resistance is not significantly reduced. Also,
The resistance of the contact portion changes depending on the contact material and the contact pressure. In general, contact materials are required to have various characteristics such as barrier performance and welding resistance as well as conductivity, so special alloys are used, and materials such as pure copper cannot be used as they are. . Therefore, reducing the resistance of the contact portion due to the change of the contact affects other performances of the vacuum valve, and therefore cannot be directly applied to the conventional vacuum valve.

On the other hand, the resistance of the electrode portion excluding the contact is
It changes depending on the structure that generates the axial magnetic field. In the electrode structure shown in FIG. 4, the current path may be long and the resistance may be large. In order to reduce the resistance, it is conceivable to increase the thickness of the coil electrode or increase the number of divisions of the coil electrode.However, such a method reduces the magnetic field strength in the axial direction generated between the electrodes and In some cases, excellent blocking performance could not be obtained. Further, the electrodes become large, which causes various problems in manufacturing a vacuum valve, which may reduce reliability.

Next, in the electrode structure shown in Japanese Patent Publication No. 3-59531, the resistance of the electrode portion can be changed by changing the number of grooves for forming an oblique current path and the inclination thereof. In such a case, as in the case of the above-described structure, the magnetic field strength in the axial direction generated between the electrodes is reduced, and in some cases sufficient blocking performance cannot be obtained.

Further, since the spiral groove is formed in the cylindrical portion, it is difficult to manufacture the groove formed in the cylindrical portion, and it takes a long time to manufacture the groove. Further, since the groove is formed in the electrode portion and the electrode has a cylindrical shape having a hollow portion, the electrode may be deformed due to an impact force when the electrode is inserted or the like. When the electrode is deformed, the strength of the magnetic field in the axial direction may be reduced, and the distribution may be uneven, which may deteriorate the blocking performance. Therefore, a structure in which reinforcement is arranged in the hollow portion of the cup-shaped electrode is conceivable,
The structure is complicated and the manufacturing is difficult. It is an object of the present invention to provide a highly reliable vacuum valve having excellent energization performance and interruption performance.

[0015]

In order to achieve the above object, the present invention provides a vacuum valve in which a contact is fixed to the facing surfaces of a pair of electrodes that are arranged to face each other in a vacuum container so that they can come into contact with and separate from each other. Is a columnar shape having grooves formed so as to generate an axial magnetic field between the electrodes, and an interposition part having an insulating part and a conducting part is provided between the electrode and the contactor. .

[0016]

In such a structure, by forming the insulating part and the conducting part as the interposing part between the electrode and the contact, the current path is restricted so that the current mainly flows only in the conducting part, and the current is generated between the electrodes. It is possible to stabilize the axial magnetic field.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a plan view of a movable electrode of a vacuum valve showing one embodiment of the present invention, and FIG. 2 is a side view thereof. In these figures, the movable electrode 3B is attached to the tip of the movable energizing shaft 5B.
Is attached to the movable electrode 3B, and an interposing portion composed of current-carrying portions 7A and 7B and the other insulating portion 8 is provided on the front surface of the movable electrode 3B, and a contactor 4B is fixed to the front surface. The movable electrode 3B is made of copper with high conductivity and is formed in a columnar shape. In addition, the cylindrical movable electrode 3B
The grooves 6A and 6B are formed symmetrically. In this embodiment, the case where the two-system grooves 6A and 6B are formed is shown.

A groove 6 is provided between the movable electrode 3B and the contact 4B.
Current-carrying portions 7A and 7B are formed at corners formed by the ends of A and 6B and the outer periphery of the movable electrode 3B on the side of the central axis of the electrode 3B so as to have a predetermined angle with respect to the central axis that can improve electrical performance. Other than that, the portion 8 between the contacts 4B is provided with an interposing portion made of an insulating portion. In such a configuration, the current flows from the movable energizing shaft 5B to the contact 4B, but does not flow linearly in parallel to the axial direction due to the grooves 6A and 6B. That is, as shown by an arrow C, first, obliquely flows from the lower part of the grooves 6A and 6B as shown by an arrow D, and then the movable electrode 3B.
Flows to the contactor 4B through the current-carrying portions 7A and 7B of the insertion part between the contactor 4B and the contactor 4B, and further flows from the center of the movable current-carrying shaft 5B not only in the radial direction but in an arc shape with a radius from the central axis. . Therefore, the directional component of the current should be divided into a component in the direction parallel to the center of the current-carrying shaft in the direction of the current-carrying parts 7A, 7B from the center of the current-carrying shaft and an arc-shaped component as well as the radial component from the center of the current-carrying shaft. You can In this way, the current flows through the contactor 4B and flows through the arc generated in the vacuum to the opposing fixed-side contactor (not shown). Further, the fixed electrode (not shown) has the same structure and the same current flows.

As described above, according to this embodiment, an arc-shaped current can be generated as a current flowing through the electrodes, and this arc-shaped current causes a magnetic field in the axial direction parallel to the arc between the electrodes. Occur. This axial magnetic field can diffuse the arc generated between the contacts when the current is cut off, as in the case of a large current region, similar to the conventional electrode that uses a coil electrode to generate an axial magnetic field. Therefore, the blocking performance can be improved. Furthermore, instead of simply providing an interposing portion between the movable electrode and the contactor, an energizing portion is formed so that a current flows only in a predetermined portion, and other portions are insulating portions, so that the current path is limited, It is possible to stabilize the strength of the axial magnetic field regardless of the arc firing point.

As a means for generating a magnetic field in the axial direction, a groove is formed obliquely with respect to a cylindrical electrode, so that the electrode portion has a simpler structure than the electrode shown in FIG. It is easy to reduce the resistance of the electrodes. Therefore, it is possible to reduce the heat generated inside the vacuum valve during energization. Further, since it is possible to promote the transfer of heat in the axial direction due to the contact resistance between the contacts, which are the largest heat sources in the vacuum valve, it is possible to promote the heat dissipation to the outside of the vacuum valve. As a result, the cooling effect of the vacuum valve can be improved, so that the current-carrying capacity can be increased.

On the other hand, compared to the cylindrical shape shown in Japanese Patent Publication No. 3-59531, the mechanical strength can be improved with a simple structure.
Since the groove is not spiral, manufacturing is easy. Since the mechanical strength is improved, it is possible to prevent the electrode from being deformed, so that a stable breaking performance can be always obtained.

Further, according to the research by the present inventors, by setting the resistivity of the insulating portion 8 of the insertion portion to be 40 times or more the resistivity of the conducting portions 7A and 7B, the current shunted to the insulating portion 8 can be obtained. It was found that the current in the current-carrying part can be suppressed to several percent or less. If this is applied to the vacuum valve of this embodiment, a more remarkable effect can be obtained.

[0023]

As described above, according to the present invention, in a vacuum valve in which a contactor is fixed to the facing surfaces of a pair of electrodes which are arranged so as to be able to come into contact with and separate from each other in a vacuum container, the electrodes are arranged between the electrodes. Since it has a columnar shape with a groove formed so as to generate a directional magnetic field, and an insertion portion having an insulating portion and a current-carrying portion is provided between the electrode and the contactor, the current-carrying performance and the breaking performance are excellent. A vacuum valve can be obtained.

[Brief description of drawings]

FIG. 1 is a plan view of a movable electrode of a vacuum valve showing an embodiment of the present invention.

FIG. 2 is a side view of a movable electrode of a vacuum valve showing an embodiment of the present invention.

FIG. 3 is a vertical sectional view of a typical vacuum valve.

FIG. 4 is a view on arrow BB of FIG.

[Explanation of symbols]

 6A, 6B ... Grooves, 7A, 7B ... Conducting section, 8 ... Insulating section.

Claims (2)

[Claims] 1. A vacuum valve in which a contactor is fixed to the facing surfaces of a pair of electrodes that are arranged to face each other in a vacuum container so that they can come into contact with and separate from each other, and a column formed with a groove so that the electrodes generate an axial magnetic field. A vacuum valve having a shape, wherein an interposition part having an insulating part and a conducting part is provided between the electrode and the contact. 2. The vacuum valve according to claim 1, wherein the resistivity of the insulating portion of the insertion portion is 40 times or more the resistivity of the conducting portion.