JP2004235121A - Vacuum circuit breaker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the following problem: a vacuum vessel cannot be miniaturized, since electrodes are made of copper and a copper alloy material, but their withstand voltage characteristics in vacuum is low, in a vacuum circuit breaker. <P>SOLUTION: The vacuum vessel 2 of this vacuum circuit breaker 1 is composed of a metallic tube 3, an insulating tube 4 and a metallic seal part 5. A fixed electrode 6 and a movable electrode 7 in the vacuum vessel 2 are disposed in a space surrounded by the metallic tube 3. Electric field shields 13A, 13B of stainless steel are disposed around the electrodes 6, 7 facing the metallic tube 3. Thereby, dielectric strength between the peripheral ends of the electrodes 6, 7 and the metallic tube 3 increases, and the vacuum vessel 2 can be miniaturized. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a vacuum circuit breaker that is reduced in size while improving a shield around an electrode arranged in a vacuum vessel.
[0002]
[Prior art]
In general, if the strength of the electric field is the same in a vacuum, the withstand voltage characteristics vary greatly depending on the material, and stainless steel has a withstand voltage characteristic several times that of copper and copper alloy. Further, regardless of the base material, coating with chromium provides characteristics intermediate between stainless steel and copper. Based on such knowledge, in a vacuum circuit breaker, a material having low withstand voltage characteristics needs to reduce the intensity of an electric field.
[0003]
In a vacuum circuit breaker, a pair of openable and closable electrodes, for example, a fixed electrode and a movable electrode are arranged in a vacuum vessel, and a vacuum state is maintained while the movable electrode is in contact with or separated from the fixed electrode. Opening and closing operation. In this case, a bellows is used to maintain the vacuum state in the vacuum vessel while allowing the movable electrode to move. One end of the bellows is fixed to a movable rod for a movable electrode, and the bellows moves, and the other end is fixed to an end surface of a vacuum vessel so as to expand and contract.
[0004]
Generally, the vacuum container is formed by sealing both ends of an insulating cylinder molded of a ceramic material or the like with a metal sealing member. The inside of this vacuum container is evacuated and the electrodes are arranged. Patent Document 1 can be cited as a vacuum circuit breaker of such a technique.
[0005]
As the vacuum vessel of the vacuum circuit breaker, in addition to the types described above, a copper metal cylinder, an insulating cylinder joined to both ends of the metal cylinder, and a metal sealing portion for sealing the end of the insulating cylinder were formed. There are also types. A fixed electrode made of copper and a copper alloy and a movable electrode are arranged to face each other in a vacuum vessel comprising such a metal cylinder, an insulating cylinder, and a metal sealed portion, and the movable electrode can be electrically opened and closed by coming into contact with and separating from the fixed electrode. Thus, a vacuum circuit breaker is configured. In this case, the metal cylinder is arranged and configured to surround the fixed electrode and the movable electrode, in other words, to be at a position where the fixed electrode and the movable electrode face the metal cylinder.
[0006]
As described above, since the metal cylinder surrounds the fixed electrode and the movable electrode, that is, since the metal cylinder is opposed to the fixed electrode and the movable electrode, most of the metal vapor generated and scattered when the electrode is opened is the metal cylinder. Adheres to the inner peripheral surface of As a result, almost no metal vapor adheres to the insulating cylinder, and the insulating cylinder can be prevented from being broken.
[0007]
In this case, the withstand voltage characteristics between the outer peripheral end of the electrode made of copper and a copper alloy and the metal tube made of copper are deteriorated as described above.
[0008]
[Patent Document 1]
JP-A-11-195357
[Problems to be solved by the invention]
Therefore, the problem can be solved by increasing the distance between the outer peripheral end of the electrode and the metal cylinder and reducing the intensity of the electric field. However, in this case, the radial dimension of the vacuum vessel increases, and the size of the vacuum circuit breaker cannot be avoided.
[0010]
The present invention has been made in view of the above prior art, and provides a vacuum circuit breaker that can be downsized while maintaining good withstand voltage characteristics without increasing a distance between an outer peripheral end of an electrode and a metal tube. With the goal.
[0011]
[Means for Solving the Problems]
In order to solve the above problems, the invention according to the present application is provided with a copper metal cylinder for preventing destruction at the time of joining the insulating cylinder, an insulating cylinder joined to both ends of the metal cylinder, and an outer end of the insulating cylinder. And a pair of openable and closable electrodes disposed in the vacuum vessel, and a stainless steel seal is provided around the electrodes facing the metal cylinder side. By providing such an electric field shield, the withstand voltage characteristic is improved depending on the material, and the diameter of the vacuum vessel is reduced.
[0012]
In the invention according to the present application, an electric field shield made of stainless steel or the like is disposed around an electrode opposed to the metal cylinder side, and the electric field shield is protruded from the electric field shield side electrode tip to the opposite electrode tip side. The arrangement is characterized in that the strength of the electric field of the electrode is reduced to improve the withstand voltage characteristics, and the length of the vacuum vessel is reduced.
[0013]
Further, the invention according to the present application is characterized in that at least one of the electric field shield and the metal cylinder is coated with a chromium layer on the surface to improve the withstand voltage characteristics, and the size of the vacuum vessel is reduced.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0015]
<First embodiment>
A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a sectional view showing a vacuum vessel of a vacuum circuit breaker used for a high voltage from a side. FIG. 2 is a sectional view showing the electrode used in FIG. 1 from the side.
[0016]
The vacuum vessel 2 of the vacuum circuit breaker 1 includes a central metal tube 3, insulating tubes 4 provided at both ends of the metal tube 3, and a metal sealing portion 5 provided at an outer end of the insulating tube 4 to seal. And the inside is in a vacuum state. In the vacuum vessel 2, a pair of fixed electrodes 6 and a movable electrode 7 that can be opened and closed are arranged to face each other. A fixed rod 6A and a movable rod 7A extend from the back of the fixed electrode 6 and the movable electrode 7 to the outside of the vacuum vessel. A bellows 8 for moving the movable electrode 7 to the fixed electrode 6 is attached between the movable rod 7A and the vacuum vessel 2. The bellows 8 enables the movable electrode 7 to open and close the fixed electrode 6 in a vacuum state.
[0017]
In this case, the metal tube 3 is arranged and configured so as to surround the fixed electrode 6 and the movable electrode 7, in other words, the position where the fixed electrode 6 and the movable electrode 7 face the metal tube 3.
[0018]
A first end electric field shield 10 that covers the bellows 8 is attached to the movable rod 7A. A second-part end-part electric field shield 11 that covers a space between the metal sealing unit 5 and a part of the insulating cylinder 4 is attached to the metal sealing unit 5. An intermediate electric field shield 12 that covers the metal tube 3 and a part of the insulating tube 4 is provided on the metal tube 3 facing the fixed electrode 6 and the movable electrode 7.
[0019]
The fixed electrode 6 and the movable electrode 7 facing the metal cylinder 3 are covered with electric field shields 13A and 13B. The electric field shield 13A is attached to the fixed rod 6A so as to surround the periphery of the fixed electrode 6. The electric field shield 13 </ b> B is attached to the movable electrode 7 so as to surround the movable electrode 7. As the electric field shields 13A and 13B, a stainless member that is difficult to discharge is used.
[0020]
For this reason, the dielectric strength between the fixed electrode 6 and the movable electrode 7 and the metal tube 3 is improved by the electric field shields 13A and 13B made of stainless steel. Therefore, even if the size of the electric field shields 13A and 13B increases, the fixed electrode 6 and the distance between the movable electrode 7 and the metal tube 3 can be reduced, and the diameter of the vacuum vessel 2 can be reduced. As a result, the size of the vacuum circuit breaker 1 can be reduced.
[0021]
The materials of the electric field shields 13A and 13B include, in addition to stainless steel, a copper-chromium alloy, a material having a copper surface coated with a chromium layer, a material having a copper alloy surface coated with a chromium layer, and a surface of a conductive material. It is also possible to use a material having a higher withstand voltage characteristic than the electrodes 6 and 7, such as a material coated with a chromium layer.
[0022]
<Second embodiment>
Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 3 shows a state in which the movable electrode 7 is brought into contact with the fixed electrode 6. FIG. 4 shows a state in which a transition has been made from the closing state to the closing state in FIG.
[0023]
As shown in FIGS. 3 and 4, the electric field shield 13 </ b> C on one side facing the metal cylinder 3 is located on the distal end 6 </ b> X of the fixed electrode 6 opposite to the distal end 7 </ b> X of the movable electrode 7 on the electric field shield 13 </ b> C side. It is formed long so as to protrude. That is, the electric field shield 13C surrounds the periphery of the movable electrode 7, and the tip 13X of the electric field shield 13C protrudes more toward the fixed electrode 6 than the tip 7X of the movable electrode 7.
[0024]
Similarly, the electric field shield 13D on the other side facing the metal cylinder 3 is longer than the distal end 6X of the fixed electrode 6 on the electric field shield 13D side so as to protrude toward the tip 7X of the movable electrode 7 opposite thereto. Is formed. That is, the electric field shield 13D surrounds the periphery of the fixed electrode 6, and the tip 13Y of the electric field shield 13D protrudes more toward the movable electrode 7 than the tip 6X of the fixed electrode 6.
[0025]
In addition, an R surface is formed on the tip portions 6X and 7X to prevent corona discharge. The electric field shields 13C and 13D use a stainless member that is a material that is difficult to discharge, so as to alleviate the electric field concentration at the electrodes 6 and 7 that easily discharge.
[0026]
In the first embodiment described above, for example, as shown in FIG. 2, if the tip 7X of the movable electrode 7 is longer than the tip 13X of the electric field shield 13 so as to protrude toward the fixed electrode 6, the tip 7X The electric field becomes stronger between the tip 13X and the discharge, and the vacuum vessel becomes longer at high voltage.
[0027]
On the other hand, in the present embodiment, unlike FIG. 2, the tip 13X of the electric field shield 13C on one side is longer than the tip 7X of the movable electrode 7 so as to protrude toward the tip X6 of the fixed electrode 6. Is formed. The distal end 13Y of the electric field shield 13D on the other side is formed to be longer than the distal end 6X of the fixed electrode 6 so as to protrude toward the distal end 7X of the movable electrode 7. Therefore, in the blocking state in FIG. 4 in which the movable electrode 7 is separated from the fixed electrode 6 from the closed state in FIG. 3, the electric field concentrates on the distal ends 13X and 13Y of the electric field shields 13C and 13D, and the fixed electrode 6 and the movable electrode 7 The electric field between them can be reduced. As a result, the gap length between the fixed electrode 6 and the movable electrode 7 can be shortened by an amount corresponding to the relaxation of the electric field, and the length dimension (axial dimension) of the vacuum vessel 2 can be reduced. The vessel 1 can be reduced in size.
[0028]
For the electric field shields 13C and 13D that cause the electric field concentration as described above, a material that is difficult to discharge is used, and the electric field at the electrodes 6 and 7 that easily discharge is reduced.
[0029]
The materials of the electric field shields 13C and 13D include, in addition to stainless steel, a copper-chromium alloy, a material having a copper surface coated with a chromium layer, a material having a copper alloy surface coated with a chromium layer, and a surface of a conductive material. It is also possible to use a material having a higher withstand voltage characteristic than the electrodes 6 and 7, such as a material coated with a chromium layer.
[0030]
<Third embodiment>
Next, a third embodiment of the present invention will be described. In the third embodiment, in the first and second embodiments shown in FIGS. 1 to 4, an electric field such as the inner peripheral surface of the metal cylinder 3 and the surface of the electric field shields 13A, 13B, 13C, and 13D is generated. Chrome plating is applied to strong places. By applying chromium plating (covering the chromium layer) in this manner, the dielectric strength is improved, so that the vacuum vessel 2 can be further reduced in size, and as a result, the vacuum circuit breaker 1 can be further reduced in size.
[0031]
【The invention's effect】
As described above in detail with the embodiments, according to the present invention, by improving the material and shape around the electrode, the dimension between the electrode and the metal tube can be reduced (radial dimension can be reduced), and the fixed electrode can be reduced. Since the dimension between the electrode and the movable electrode can be reduced (the dimension in the axial direction can be reduced), the vacuum vessel and thus the vacuum circuit breaker can be reduced in size.
[Brief description of the drawings]
FIG. 1 is a sectional view showing a vacuum circuit breaker according to a first embodiment of the present invention.
FIG. 2 is a sectional view showing a part of an electrode and an electric field shield used in the first embodiment.
FIG. 3 is a sectional view showing a part of an electrode and an electric field shield used in a vacuum circuit breaker according to a second embodiment of the present invention in an electrode joined state.
FIG. 4 is a cross-sectional view showing an electrode and an electric field shield used in a vacuum circuit breaker according to a second embodiment of the present invention in an electrode open state.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Vacuum breaker 2 Vacuum container 3 Metal cylinder 4 Insulation tube 5 Metal sealing part 6 Fixed electrode 6A Fixed rod 6X Tip 7 Moving electrode 7A Moving rod 7X Tip 13A, 13B, 13C, 13D Electric field shield 13X, 13Y Tip

Claims (5)

A metal container, an insulating tube connected to both ends of the metal tube, and a vacuum container having a sealing portion for sealing the end of the insulating tube,
In a vacuum circuit breaker provided with a pair of openable and closable electrodes arranged in a space surrounded by the metal cylinder in the vacuum vessel,
A vacuum circuit breaker, wherein an electric field shield made of a material having higher withstand voltage characteristics than the electrode is arranged in a state surrounding the periphery of the electrode. A metal container, an insulating tube connected to both ends of the metal tube, and a vacuum container having a sealing portion for sealing the end of the insulating tube,
In a vacuum circuit breaker provided with a pair of openable and closable electrodes arranged in a space surrounded by the metal cylinder in the vacuum vessel,
In a state surrounding the periphery of the electrode, an electric field shield made of a material having a higher withstand voltage characteristic than the electrode is arranged,
A vacuum circuit breaker, wherein the electric field shield is arranged such that a front end of the electric field shield protrudes to an electrode side opposite to a front end of an electrode provided with the electric field shield. The vacuum circuit breaker according to any one of claims 1 to 2, wherein at least one of a surface of the electric field shield and an inner peripheral surface of the metal cylinder is coated with a chromium layer. . The vacuum circuit breaker according to any one of claims 1 to 3, wherein the electric field shield is made of stainless steel. The electric field shield may be any one of a copper chromium alloy, a material having a copper surface coated with a chromium layer, a material having a copper alloy surface coated with a chromium layer, and a material having a conductive material coated with a chrome layer. The vacuum circuit breaker according to any one of claims 1 to 3, wherein the vacuum circuit breaker is formed of one.

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