JPH10214545A - Vacuum valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the wear of an arc shield due to arc. SOLUTION: A vacuum valve has a vacuum container 4 in which both ends of an insulating cylinder 1 are sealed with end plates 2, 3, a pair of contacts 7, 8 arranged in the vacuum container 4 to oppose each other in a freely contacting/separating manner and an arc shield 5 circulated around a pair of contacts 7, 8 via a vacuum gap 24. The arc shield 5 is covered with a magnetic shield 20 which is formed of magnetic material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum valve incorporated in a vacuum circuit breaker for contacts, and more particularly to a vacuum valve in which an arc generated between the contacts when switching a current is not affected by an external magnetic field.

[0002]

2. Description of the Related Art FIG. 7 is a sectional view showing the structure of a conventional vacuum valve. The vacuum vessel 4 is made of an insulating tube 1 made of a ceramic material and end plates 2 and 3 hermetically bonded to both ends thereof, and the inside thereof is kept at a vacuum. A movable rod 9 and a fixed rod 10 penetrate the end plates 2 and 3, respectively.
The movable rod 9 is airtightly joined to the end plate 2 via the bellows 6, and the fixed rod 10 is airtightly joined directly to the end plate 3. Ends of the movable rod 9 and the fixed rod 10 on the inner side of the vacuum vessel 4 are respectively joined to contact points 7 and 8 facing each other. An arc shield 5 made of a cylindrical metal is arranged around the pair of contacts 7 and 8 via a vacuum gap 24. This arc shield 5 is attached to the inner wall of the insulating cylinder 1 via a mounting bracket 11.

In FIG. 7, an upper end of a movable rod 9 and a lower end of a fixed rod 10 are respectively connected to a main circuit (not shown). The upper end of the movable rod 9 further
It is connected to a drive (not shown). The movable rod 9 is moved upward by the driving device, and the pair of contacts 7 and 8 are moved.
The main circuit current is interrupted by disconnecting. The bellows 6 vertically supports the movable rod 9 in an airtight state by expanding and contracting. The arc shield 5 is made of copper or stainless steel, and prevents metal vapor generated by arc heat when the contacts 7 and 8 are separated from attaching to the insulating cylinder 1. That is, the metal vapor adheres to the inner wall of the arc shield 5 to prevent the insulation of the insulating cylinder 1 itself from lowering. Since the arc shield 5 itself is conductive, even if metal vapor adheres, it does not affect the breaking performance at all.

FIG. 8 is a side view showing the structure of a vacuum circuit breaker incorporating the vacuum valve of FIG. A movable rod 9 and a fixed rod 10 are pulled up and down from a vacuum container 4 of a vacuum valve. The movable rod 9 is connected to the main circuit conductor 16 via a flexible conductor 19. Further, a driving rod 13 is attached to the movable rod 9.
The drive rod 13 is connected to the conversion lever 1 via a connecting pin 14.
5. On the other hand, the fixed rod 10 is directly
It is connected to the main circuit conductor 17. Further, the fixing rod 10 is fixed to the carriage 12 via an insulator 25. The carriage 12 houses a drive device (not shown). The conversion lever 15 is connected to the driving device. The conversion lever 15 is rotated by the driving device, whereby the driving rod 13 and the movable rod 9 are moved up and down to bring the contacts 7, 8 into and out of contact. The main circuit current can be opened and closed by flowing the main circuit current in the direction of arrow I and bringing the contacts 7 and 8 into and out of contact.

[0005]

However, the conventional device as described above has a problem in that the arc between the contacts has a place where the arc is elongated for a long time, and the arc may come into contact with the arc shield. That is, FIG.
Is a configuration in which the vacuum circuit breaker is interrupting the main circuit current, and an arc 18 is generated between the contacts 7 and 8.
Since the main circuit current flows in a reverse U-shape as shown by the arrow I, a magnetic field orthogonal to the arc 18 is formed, and an electromagnetic force acts on the arc 18 in the direction of the arrow F. Due to this electromagnetic force, the arc 18 may be elongated in a left-hand shape at the left ends of the contacts 7 and 8, and may directly contact the arc shield. When the arc 18 comes into contact with the arc shield, the arc heat itself is locally consumed by the arc heat. In some cases, the life of the vacuum valve is determined by the wear of the arc shield itself.

An object of the present invention is to prevent the arc shield from being worn by an arc.

[0007]

According to the present invention, in order to attain the above object, according to the present invention, a vacuum container having both ends of an insulating cylinder sealed with an end plate is provided in the vacuum container so as to be capable of contacting and separating. A pair of contacts and an arc shield that goes around the pair of contacts via a vacuum gap, wherein the outer periphery of the arc shield is covered with a magnetic shield made of a magnetic material. Good to do. Thereby, the external magnetic field formed by the main circuit current flowing in the inverted U shape is shielded, and the electromagnetic force acting on the arc between the contacts is reduced. Thereby, the arc does not contact the arc shield.

In this configuration, both ends of the magnetic shield may be rounded toward the inside diameter so as to surround both ends of the arc shield. This alleviates the electric field at the arc shield end. In such a configuration, both ends of the arc shield may be rounded to the outer diameter side so as to surround both ends of the magnetic shield. This also reduces the electric field at the arc shield end.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments. FIG. 1 is a sectional view showing a configuration of a vacuum valve according to an embodiment of the present invention. A magnetic shield 20 is brazed to the outer periphery of the arc shield 5. The magnetic shield 20 is attached to the insulating cylinder 1 via the attachment fitting 11. The rest of FIG. 1 is the same as the conventional configuration of FIG. 7, and the same portions are denoted by the same reference numerals and detailed description thereof will be omitted.

In FIG. 1, a magnetic shield 20 is made of a ferromagnetic material such as iron, and shields an external magnetic field that enters between the contacts 7 and 8. Therefore, even if an external magnetic field generated by the main circuit current flowing in the inverted U-shape is generated, the magnetic field does not affect the arc between the contacts 7 and 8. The magnetic shield 20 only needs to be configured to cover the outer periphery of the arc shield 5, and the magnetic shield 2 and the arc shield 5 do not necessarily need to be in contact with each other. By covering the outer periphery of the arc shield 5 with the magnetic shield 20, the arc stays substantially between the contacts 7 and 8 and does not contact the arc shield 5.
Thereby, the arc shield 5 is never consumed by the arc heat, and the life of the vacuum valve is longer than that of the conventional one. Although the magnetic field can be shielded by arranging the magnetic shield 20 on the inner wall side of the arc shield 5, the withstand voltage performance of the vacuum valve itself is inferior.

FIG. 2 is a sectional view showing the structure of a vacuum valve according to another embodiment of the present invention. Contact 7A, 8A
And a slit 21 is formed in a corrugated shape.
Others are the same as the configuration of FIG. This corrugated contact shape is known, and the contact 7 is formed by the slit 21.
A current flows in the lateral direction (circumferential direction) of
A, and generates a transverse magnetic field between A and 8A. Since the arc is pushed in the lateral direction by the lateral magnetic field and does not stay at one place, there is an advantage that the wear of the contacts 7A and 8A is reduced. As the surroundings of the contacts 7A and 8A are covered with the magnetic shield 20, the external magnetic field due to the main circuit current is shielded and the arc shield 5 is not worn out, as in the case of FIG.

As another structure of the vacuum valve, although not shown, the contacts may be formed in a spiral shape instead of the corrugated shape as shown in FIG. This spiral contact is also known, in which a current is spirally flowed in the lateral direction of the contact to generate a lateral magnetic field between the contacts, and the effect is the same as that of the corrugated contact. FIG. 3 is a cross-sectional view showing a configuration of a vacuum valve according to still another embodiment of the present invention, and FIG. 4 is an enlarged cross-sectional view of a portion A in FIG. Upper and lower ends 22A of the magnetic shield 22 are rounded toward the inner diameter side so as to surround both ends of the arc shield 5, respectively. Thus, the electric field at the end of the arc shield 5 is reduced. Therefore, the withstand voltage performance of the vacuum valve itself is improved, and the size of the vacuum valve can be reduced. Further, the roundness of the magnetic shield 22 can support the arc shield 5, and the joining between the magnetic shield 22 and the arc shield 5 becomes mechanically strong.

FIG. 5 is a sectional view showing the structure of a vacuum valve according to a further different embodiment of the present invention, and FIG.
FIG. 6 is an enlarged sectional view of a portion B in FIG. 5. Both ends 23A of the upper and lower ends of the arc shield 23 are rounded to the outer diameter side so as to surround both ends of the magnetic shield 20 respectively. Thereby, the electric field at the end of the arc shield 23 is reduced. Therefore, also in this case, the electric resistance performance of the vacuum valve itself is improved, and the vacuum valve can be reduced in size. Further, the arc shield 23 is supported by the roundness of the arc shield 23, and the joining between the magnetic shield 20 and the arc shield 23 is mechanically strong.

[0014]

As described above, in the present invention, the outer periphery of the arc shield is covered with the magnetic shield made of a magnetic material. This prevents the arc from contacting the arc shield and extends the life of the vacuum valve. In such a configuration, both ends of the magnetic shield may be rounded toward the inner diameter side so as to surround both ends of the arc shield. As a result, the electric field at the end of the arc shield is alleviated, and the withstand voltage performance of the vacuum valve itself is improved and the size can be reduced. Also, the magnetic shield and the arc shield can be mechanically and strongly joined. In the formation, both ends of the arc shield may be rounded to the outer diameter side so as to surround both ends of the magnetic shield. This also reduces the electric field at the arc shield end. This also alleviates the electric field at the end of the arc shield, improves the withstand voltage performance of the vacuum valve itself, and enables downsizing. Also, the magnetic shield and the arc shield can be mechanically and strongly joined.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a configuration of a vacuum valve according to an embodiment of the present invention.

FIG. 2 is a sectional view showing the configuration of a vacuum valve according to another embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a configuration of a vacuum valve according to still another embodiment of the present invention.

FIG. 4 is an enlarged sectional view of a portion A in FIG. 3;

FIG. 5 is a cross-sectional view showing a configuration of a vacuum valve according to still another embodiment of the present invention.

FIG. 6 is an enlarged sectional view of a portion B in FIG. 5;

FIG. 7 is a sectional view showing the configuration of a conventional vacuum valve.

8 is a side view showing a configuration of a vacuum circuit breaker in which the vacuum valve of FIG. 7 is incorporated.

[Explanation of symbols]

1: insulating tube, 2, 3: end plate, 4: vacuum container, 5, 23:
Arc shield, 6: Bellows, 7, 8, 7A, 8A:
Contact, 9: movable rod, 10: fixed rod, 11: mounting bracket, 18: arc, 20, 22: magnetic shield, 2
2A, 23A: end, 24: vacuum gap

Claims (3)

[Claims] 1. A vacuum container in which both ends of an insulating cylinder are sealed with an end plate, a pair of contacts arranged in the vacuum container and opposed to each other so as to be able to contact and separate from each other. A vacuum valve comprising a rotating arc shield, wherein the outer periphery of the arc shield is covered with a magnetic shield made of a magnetic material. 2. The vacuum valve according to claim 1, wherein both ends of the magnetic shield are rounded toward the inside diameter so as to surround both ends of the arc shield. 3. The vacuum valve according to claim 1, wherein both ends of the arc shield are rounded to the outer diameter side so as to surround both ends of the magnetic shield.