JPH076672A - Vacuum valve - Google Patents

Abstract

PURPOSE:To provide a vacuum valve such as for maintaining external insulation. CONSTITUTION:A pair of electrodes 4, 8 are provided to be opposed in a butt condition capable of coming into contact and separating in an insulated vessel 1. A vertical magnetic field is given by permanent magnets 10, 10 between both electrodes 4, 8, and the magnetic field acts in also the periphery of both electrodes 4, 8. However, a barrier 14 consisting of ferromagnetic material is provided in the insulated vessel 1, thus to shield leakage to the outside of the insulated vessel 1. Consequently, a ferromagnetic substance, floated in the atmosphere, is prevented from being attracted by the magnetic field to adhere to a surface of the insulated vessel 1.

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 a pair of electrodes which can be contacted and separated from each other in an insulating container, and a barrier which surrounds the electrodes.

[0002]

2. Description of the Related Art A vacuum valve is made into a closed container by a metal lid which covers openings at both ends of a cylindrical insulating container, and the inside thereof is in a vacuum state. The movable electrode and the fixed electrode are provided to face each other from both metal lids, and the electric paths are opened and closed by contacting and separating the tips of these electrodes in a butted manner. In this vacuum valve, a technique is known in which a longitudinal magnetic field is applied between both electrodes by a permanent magnet to confine the generated arc between both electrodes.

[0003]

When a longitudinal magnetic field is applied between both electrodes in this way, the magnetic field also extends outside the insulating container and attracts a ferromagnetic substance such as iron powder floating in the air as dust. It will be. For this reason, there is a problem that the ferromagnetic material having conductivity is adsorbed to the outer surface of the insulating container, and the insulation of the outer surface of the insulating container is deteriorated.

Therefore, an object of the present invention is to provide a vacuum valve that maintains external insulation.

[0005]

Therefore, in the present invention, a barrier of a ferromagnetic material is provided in the insulating container so as to apply a longitudinal magnetic field between both electrodes and prevent the magnetic field from leaking out of the insulating container. It is provided.

[0006]

In the insulating container, a pair of electrodes are provided so as to face each other so that they can come into contact with and separate from each other. A longitudinal magnetic field is applied between the both electrodes, and the magnetic field also acts around the both electrodes. However, a barrier made of a ferromagnetic material is provided inside the insulating container, which can prevent the magnetic field from leaking outside the insulating container. Therefore, the ferromagnetic substance floating in the atmosphere is not attracted by the magnetic field and is not adsorbed on the surface of the insulating container.

[0007]

As described above, according to the present invention, the magnetic field of both electrodes in the insulating container is shielded by the ferromagnetic barrier to prevent the magnetic action to the outside. It has the effect of increasing the reliability of insulation.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to FIGS.

As shown in FIG. 1, the vacuum valve of this embodiment is a closed container in which metal lids 2 and 3 are fixed to both open ends of a cylindrical insulating container 1 made of insulating ceramics such as porcelain. There is. The movable electrode 4 formed by fixing the contact plate 6 to the tip of the conductive shaft 5 is attached to the metal lid 2 on one side, and the contact plate 6 is fixed to the tip of the conductive shaft 9 on the other metal lid 3. The fixed electrodes 8 are provided so as to penetrate therethrough, and the contact plates 6 and 6 at the tips of the fixed electrodes 8 are arranged in a butt shape so as to face each other coaxially at the center of the insulating container 1. Then, the movable electrode 4 is moved back and forth by a driving device (not shown) to contact or separate the contact plates 6 and 6. The movable electrode 4
Is provided with a bellows 7 and a vacuum state is maintained.

At the tip surfaces of the conductive shafts 5 and 9, the accommodating portion 5a,
9a is recessed, and the disk-shaped permanent magnet 10 is accommodated in the accommodating portions 5a, 9a as shown in FIG. 1 or 2. Since the tips of the electrodes 4 and 8 have the same structure, the movable electrode 4 will be described below. A spacer 11 having a lower thermal conductivity than that of a copper alloy, which is a constituent material of the electrode 4, is interposed between the movable electrode 4 and the accommodating portion. It is housed in 5a. The front surface is covered with the contact plate 6. This contact plate 6
Is a disk having a diameter larger than the tip surface of the conductive shaft 5, and is welded to the tip of the conductive shaft 5 by brazing 13. Further, a leg portion 6a protruding in a ring shape is provided on the back surface of the contact plate 6 and protrudes into the accommodating portion 5a. The permanent magnet 10 is attached to the leg 6a via the spacer 11 with the back surface and the side surface separated from each other by the attraction force between the permanent magnet 10 housed on the fixed electrode 8 side and the conductive shaft 5. Abutment is arranged. Therefore, the permanent magnet 10 comes into contact with the leg portion 6a via the spacer 11 in a ring shape to reduce a heat transfer area, and an excessive temperature rise of the permanent magnet 10 is prevented.
An axial longitudinal magnetic field is applied between the electrodes 4 and 8 by the permanent magnets 10 to disperse the arc generated at the time of interruption, thereby preventing local heating.

A metal barrier 14 is attached to the projection 1a provided on the inner surface of the insulating container 1. This barrier 14 is formed in a cylindrical shape surrounding both electrodes 4 and 8 and serves as an arc shield which prevents metal gas generated from both electrodes 4 and 8 from being deposited on the inner peripheral surface of the insulating container 1 by an arc at the time of interruption. ing. As shown in FIGS. 1 and 3, the barrier 14 of this embodiment is made of pure iron, a martensite-based or a ferrite-based ferromagnetic metal, and is formed into a cylindrical shape surrounding the electrodes 4 and 8 for energization. Both electrodes inside
Are attached to the projections 1a on the inner peripheral surface so as to alleviate the electric field and to shield the generated metal gas from the insulating container 1. As the ferromagnetic metal, it is desirable to use a so-called soft magnetic material having a small coercive force. The barrier 14 is provided with a short-circuit ring 15 wound around the inner and outer peripheral surfaces to form a loop circuit in the axial direction of the electrodes 4 and 8.

Next, the operation of this embodiment will be described with reference to FIGS. 3 and 4. Now, the vacuum valve is closed.
At this time, the permanent magnets 10 and 10 embedded in the electrodes 4 and 8
Thus, a magnetic field M is applied, and the magnetic field M applies a vertical magnetic field between the electrodes 4 and 8. Then, when the electrode 4 separates from the electrode 8 and interrupts the electric path, an arc is generated, but this arc is dispersed in this longitudinal magnetic field to prevent local concentration between the contact plates 6, 6. As a result, high blocking performance is demonstrated.

This magnetic field M also acts on the outside of the periphery of the electrodes 4, 8 as shown by the thick line in FIG. 4, but since the ferromagnetic barrier 14 is provided on the outer periphery of this permanent magnet 10,
The magnetic field M is shielded by this barrier to prevent the magnetic action on the outside. Therefore, since the magnetic field M does not act outside the insulating container 1, the ferromagnetic substance floating in the atmosphere is prevented from being adsorbed on the outer surface of the insulating container 1, and the adsorbed ferromagnetic substance prevents external insulation. It does not cause a decline.

Further, a magnetic field B is generated by the alternating current A flowing through the electrodes 4 and 8, and an eddy current is generated in the barrier 14 by the magnetic field B as shown in FIG. But Barrier 1
4 is provided with a short-circuit ring 15, and the eddy current is canceled by the current flowing through the short-circuit ring 15. For this reason,
Heat generation due to eddy current loss and hysteresis loss caused by this eddy current is suppressed, and the barrier 14 is prevented from becoming high heat.

In this embodiment, the permanent magnet 10 is provided on the back surfaces of the contact plates 6 and 6 via the spacer 11 having a low thermal conductivity and is sealed to the rear conductive shafts 5 and 9 to thereby secure the permanent magnet 10. , 10 is separated from the conductive shafts 5, 9 by the attraction force between the spacers 10, and the spacer 11 abuts on the leg portion 6a of the contact plate 6 to reduce the heat transfer area from the front contact plates 6, 6. Even if both electrodes 4 and 8 generate high heat due to the arc, there is an advantage that heat is dissipated to the conductive shafts 5 and 9 to reduce heat transfer to the permanent magnet 10 and prevent deterioration of the permanent magnet 10.

In this embodiment, the arc shield is made of a ferromagnetic material to form a barrier having a simple structure. However, the barrier may be provided separately from the arc shield. it can.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view.

FIG. 2 is a front view of a contact surface of a movable electrode.

FIG. 3 is a partial sectional view.

FIG. 4 is a distribution diagram of a magnetic field.

[Explanation of symbols]

1 ... Insulating container 4 ... Movable electrode 8 ... Fixed electrode 10 ... Permanent magnet 14 ... Barrier

Claims (1)

[Claims] 1. A vacuum valve in which a pair of electrodes facing each other in an insulative container are provided so as to be able to come into contact with and separate from each other in a butt shape. A vacuum valve characterized by having a barrier formed by the body.