JPH08167356A - Vacuum circuit-breaker - Google Patents

Abstract

PURPOSE: To make a vacuum circuit-breaker for high voltage be small and light in weight and lower the manufacturing cost without deteriorating the electric field moderation of a surface of both curled part open ends, of an intermediate metal shield by shortening the length of the curled parts in the diametric direction. CONSTITUTION: Curled parts 19a, 19b, whose both ends are opened, of an intermediate metal shield 19 are so made as to be composite circular shapes in which the radius on the inner diameter side is larger than the radius on the outer diameter side. Moreover, the outer circumferential parts of a movable electrode 21 and a fixed electrode 20 are made to be partially spherical shapes and the length of the contact face side from the maximum outer circumferential point in a section of the outer circumferential part in the axial direction is made to be longer than the length of the opposed contact face side in order to give wide roundness.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum circuit breaker, and more particularly, to a high voltage vacuum circuit breaker having a shield surrounding a pair of electrodes that can be contacted and separated.

[0002]

2. Description of the Related Art FIG. 6 is a vertical sectional view of a conventional vacuum breaker for high voltage. In FIG. 6, a pair of insulating outer cylinders 1a, 1b made of glass or the like is arranged in the axial direction, and annular thin-wall sealing end fittings 2a, 3a and intermediate fittings 2b, 3b are arranged at both ends of the outer cylinders 1a, 1b. Installation, one of the intermediate fittings 2b, 3b
Is connected via a support metal fitting 5 fixed to the intermediate outer peripheral portion of the intermediate metal shield 4, and the other end metal fittings 2a, 3a.
Is an end plate made of metal such as stainless steel 6,
7, the inside of which is evacuated to a high vacuum and the vacuum container 8
Are formed. In the vacuum container 8, conductive rods 9 and 10 made of a highly conductive material such as oxygen-free copper are arranged so as to penetrate the end plates 6 and 7, respectively. The conductive rod 9 is airtightly introduced from the fixed end plate 6, and the conductive rod 10 is airtightly introduced from the movable end plate 7 through the metal bellows 13. A fixed electrode 11 and a movable electrode 12 are respectively fixed to the tips of the conductive rods 9 and 10 in a vacuum, and the movable electrode 12 has a structure in which the movable electrode 12 can be contacted and separated from the fixed electrode 11 by expanding and contracting a metal bellows 13. Has become. The intermediate metal shield 4 is made of a metal such as stainless steel and surrounds a pair of the fixed electrode 11, the movable electrode 12 and a part of the conductive rods 9 and 10. Both ends extend toward the end plates 6 and 7, and a cone is formed from the middle. The diameter shrinks,
The curl portions 4a and 4b at the open ends are annular and are fixed by a support fitting 5 which is joined and supported between the intermediate fittings 2b and 3b of the insulating outer cylinders 1a and 1b. 14
Is a fixed side auxiliary metal shield provided inside the end plate 6, 15
Is a movable side auxiliary metal shield provided inside the end plate 7 to prevent the electric field from concentrating on the tips of the end fittings 2a and 3a joined to one end of each of the insulating outer cylinders 1a and 1b. Is a shield for alleviating the electric field. Reference numeral 16 is a shield for protecting the bellows.

[0003]

The high-voltage vacuum circuit breaker is constructed such that the movable side and the fixed side are symmetrical with respect to the center of the electrodes so that the high-voltage vacuum circuit breaker can withstand the high voltage when in the cut-off position. Then, the curled portions at both ends of the intermediate metal shield 4 are curved into an annular shape having an appropriate radius to alleviate the electric field. On the other hand, since the surfaces of the fixed electrode 11 and the movable electrode 12 that face each other are substantially parallel,
Since the electric field is concentrated on the outer peripheral portion of the electrode, a rounded portion having an appropriate size is provided to alleviate the electric field at this portion.

FIG. 5 is an enlarged view of a main part showing the potential distribution of FIG. 6, and the potential distribution near the movable electrode 12, the intermediate metal shield 4, and the insulating outer cylinder 1b is equal potential line a (dotted line in the figure). ). In FIG. 5, the interval between the equipotential lines a in the curl portion 4b of the movable-side open end of the intermediate metal shield 4 and the rounded portion b on the outer periphery of the contact surface side of the movable electrode 12 is small, and electric field concentration occurs.

FIG. 4 is an enlarged view of a main portion showing the potential distribution of the structure in which the electric field concentration portion is relaxed in FIG. The curl portion 17b at the movable-side open end of the intermediate metal shield 17 is formed into an annular shape having a large radius. Further, the outer peripheral portion of the movable electrode 18 has a large rounded partial spherical shape. In the structure shown in FIG. 4, the equipotential lines a in the curl portion 17b of the intermediate metal shield 17 and the outer peripheral portion of the movable electrode 18 are coarser than those in FIG. 5, and the electric field is relaxed. But,
On the other hand, FIG. 4 in which the electric field relaxation effect is increased is compared with FIG. 5, on the other hand, the locus of the equipotential line a near the insulating outer cylinder 1b is too biased to the movable side auxiliary metal shield 15 side.
The spacing of some equipotential lines (a) becomes finer, and the insulating outer cylinder 1
The inner and outer creepage withstand voltage characteristics of a and 1b are remarkably deteriorated.
As a countermeasure against this, the outer peripheral portion of the curl portion 17b and the insulating outer cylinder 1b are
It is necessary to increase the distance between the two and make the locus of the equipotential line a near the insulating outer cylinder 1b closer to the end fitting 3a side. This leads to an increase in the size of the insulating outer cylinders 1a and 1b, which leads to an increase in the size of the vacuum breaker, resulting in a significant increase in cost. On the other hand, since the outer peripheral portion of the movable electrode 18 is formed into a partially spherical shape with a large roundness, the thickness of the movable electrode 12 becomes large and therefore the weight becomes large. This increases the size of the vacuum breaker and the size of the vacuum breaker operating device, resulting in a significant increase in cost.

[0006]

According to the present invention, the curl portions at both ends of the opening of the intermediate metal shield have a large radius on the inner diameter side and a small radius on the outer diameter side. Further, the outer peripheral shape of the fixed electrode and the movable electrode is a partial spherical shape, and
The spherical part is smaller on the non-contact surface side than on the contact surface side,
A vacuum circuit breaker with a suitable, large roundness, small size, low price, and good withstand voltage performance was constructed.

[0007]

[Function] The curl portions 4 at both ends of the intermediate metal shield 4
In the case of an annular shape, a and 4b are where the electric field concentrates on the inner diameter side annular portions facing the conductive rods 9 and 10 facing each other. Therefore, if the radius is increased only on the inner diameter side, the electric field in the annular ring at the end of the intermediate metal shield opening is relaxed. If the radius on the outer diameter side where the electric field is not concentrated is reduced, the radial dimension of the vacuum breaker can be shortened accordingly. Further, the outer peripheral portions of the fixed electrode and the movable electrode are appropriately shaped to have a partially spherical shape with a large roundness, and the contact surface side portion where the electric field is concentrated is large and the non-contact surface side portion is small. This is effective for alleviating the electric field at the outer periphery of each electrode, and because the electrode thickness can be made small, not only the electrode weight is reduced, the vacuum interrupter as a whole is also reduced, but the weight reduction of the movable electrode is It is effective for downsizing and weight saving.

[0008]

The present invention will be described below based on the illustrated embodiments. FIG. 1 shows an embodiment of the present invention.

In FIG. 1, curls at both open ends of the intermediate metal shield 19 connected to the fixed shield support fitting 5 sandwiched between the intermediate fittings 2b and 3b at one end of the outer cylinders 1a and 1b. The portions 19a and 19b have a shape in which the radius R on the conductive rods 9 and 10 side is larger than the radius r on the insulating outer cylinders 1a and 1b side. With such a shape, without increasing the radial lengths of the curl portions 19a and 19b,
The surface electric field can be relaxed.

Further, each of the conductive rods 9 and 10 and the fixed electrode 20 and the movable electrode 21 fixed to the tip end in a vacuum has a partially spherical outer peripheral portion, and in the axial outer peripheral cross section thereof, since the surface electric field is concentrated on the contact surface, the contact surface side of the maximum outer periphery point than the length L ₁ of the counter-contact surface side length L ₂
To a small spherical shape with a large roundness. FIG. 2 is an enlarged view near the movable electrode 21 of FIG. By doing so, the thickness of the electrode is reduced and the weight of the electrode is also reduced.

FIG. 3 is a vertical cross-sectional side view of essential parts showing the potential distribution near the movable electrode 21, the intermediate metal shield 19, and the insulating outer cylinder 1b of FIG. According to the locus of the equipotential line a in FIG. 3, the interval between the equipotential lines a in the curl portion 19b of the intermediate metal shield 19 and the outer peripheral portion of the movable electrode 21 becomes coarse as in FIG. 4, and the electric field is relaxed. In addition, the insulating outer cylinder 1b
In the vicinity of, as in FIG. 5, the equipotential line a is connected to the end fitting 3a.
The distance between them is close to each other, and the intervals are almost the same, so that good inner and outer creepage withstand voltage characteristics can be obtained.

[0012]

According to the present invention, the curl portions at the both ends of the intermediate metal shield have a shape that reduces the radial length even when the surface electric field strength is the same. It is effective for downsizing and cost reduction.

Further, since the thickness of the electrode can be reduced without impairing the relaxation of the electric field at the outer peripheral portion of the electrode, the weight of the electrode can be reduced, and therefore the operating device of the vacuum breaker can be downsized and the cost can be reduced. .

[Brief description of drawings]

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

FIG. 2 is a side view near the movable electrode in FIG.

FIG. 3 is a cross-sectional view of a main part showing an equipotential distribution including an electrode and a conductive rod on the movable side of FIG. 1, an intermediate metal shield, an insulating outer cylinder, a bellows protection shield, an auxiliary metal shield, and the like.

4 is a cross-sectional view of a main part showing an equipotential distribution of the specific example of FIG.

FIG. 5 is a sectional view of a conventional vacuum breaker.

FIG. 6 is a sectional view of a main part showing an equipotential distribution.

[Explanation of symbols]

1a, 1b ... Insulating outer cylinder, 2a, 3a ... End fittings, 2
b, 3b ... Intermediate metal fittings, 6, 7 ... End plate, 8 ... Vacuum container,
9, 10 ... Conductive rod, 13 ... Bellows, 14 ... Fixed side auxiliary metal shield, 15 ... Movable side auxiliary metal shield, 19 ...
Intermediate metal shield, 19a, 19b ... Curled portion at the end of the intermediate metal shield opening, 20 ... Fixed electrode, 21 ... Movable electrode.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Takashi Sato 7-1-1 Omika-cho, Hitachi-shi, Ibaraki Hitachi Ltd. Hitachi Research Laboratory (72) Inventor Yoshimi Hakada 1-chome, Kokubun-cho, Hitachi-shi, Ibaraki No. 1 inside the Kokubun Plant of Hitachi, Ltd.

Claims (2)

[Claims] Claim: What is claimed is: 1. An inside vacuum is provided by an insulating outer cylinder provided at both ends of an intermediate metal fitting, an end fitting attached to one end of the insulating outer fitting, and an end plate provided on the end fitting. And a pair of electrodes that are arranged corresponding to each other in the vacuum container and have a conductive rod that extends to the outside of the vacuum container and that can be separated from each other and that surrounds the pair of electrodes, and both ends thereof extend in the end plate direction. Then, in a vacuum circuit breaker equipped with an intermediate metal shield whose diameter is conically shortened from the middle thereof, both open end curls of the intermediate metal shield are located closer to the conductive rod than the radius of the insulating outer cylinder side. A vacuum circuit breaker characterized by having a complex annular shape with a large radius. 2. The electrode according to claim 1, wherein an outer peripheral portion of the electrode has a Rogowski electrode shape, and a length of a contact surface side from a maximum outer peripheral point is larger than a length of the anti-contact surface side in a cross section of the outer peripheral portion in the axial direction. Vacuum breaker with a large roundness.