JPH043610B2 - - Google Patents

Description

[Detailed description of the invention]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum interrupter, and particularly to a vacuum interrupter in which a contact portion of an electrode and an arc portion are made of different materials. BACKGROUND TECHNOLOGY As shown in FIGS. 5 and 6, a vacuum interrupter whose electrodes consist of a contact part and an arc part generally has two insulating cylinders 1 made of glass or insulating ceramics sealed at both ends. By joining one of the sealed fittings 2, it is made into a single insulating cylinder, and both open ends of this single insulating cylinder are connected to the other sealing fitting 2.
A pair of conductive rods 4, which can be relatively moved toward and away from each other, are coaxially sealed together by a pair of perforated disk-shaped metal end plates 3 through the respective holes of both metal end plates 3. The inner ends of both conductive rods 4 have a pair of electrodes 5 that can be freely moved in and out of the insulating cylinder, and the main components are the one insulating cylinder and both metal end plates 3. The inside of the vacuum container 6 is configured to be evacuated to a high vacuum. As the pair of electrodes 5, those having a cross section as shown in FIG. 5 are used, and the contact portion 7 is
It is made of a copper-based alloy containing 0.2 to 1% by weight of bismuth, and the arc portion 8 is made of copper.
This arc portion 8 is composed of, for example, six spiral pieces, and magnetically drives the arc generated between the pair of electrodes 5 to rotate. Problems to be Solved by the Invention Although the vacuum interrupter having the electrode 5 according to the prior art has relatively good current shearing performance, the problem is that there is a large variation in dynamic dielectric strength at the time of current shearing. However, the current cut-off value is as high as 10A, which poses the problem of generating harmful switching surges when a small current is cut off. In addition, if the arc part is made of Cu,
The strength of Cu is low (tensile strength is ^about 20Kg/mm2)
Therefore, the thickness of the arc part had to be increased, which caused the problem that the electrode was large and heavy. Means for Solving the Problems In order to improve the drawbacks of conventional electrodes in which the contact part is made of Cu-Bi and the arc part is made of Cu, the present inventors have
Cu-Cr- is known from Japanese Patent Application Laid-open No. 59-27418, and has a relatively small cutting current value (about 4 A) and good withstand voltage characteristics (more than 120 kV with a gap of 3 mm).
We focused on Mo-based metals. Furthermore, in order to reduce the thickness of the arc portion, a material with high strength may be used, but generally speaking, materials with high strength tend to have low conductivity. Therefore, the inventors made the contact part with a Cu-Cr-Mo alloy (50Cu-10Cr-40Mo, weight%), and used materials with various conductivities (hereinafter referred to as IACS) for the arc part to generate a large current. A break test was conducted. Note that the configurations of the vacuum interrupter and electrodes are the same as those shown in FIGS. 6 and 5 above,
The contact portion was ring-shaped with an outer diameter of 40 mm and an inner diameter of 20 mm, and the arc portion had an outer diameter of 80 mm and was composed of six spiral-shaped pieces. and applied voltage 12kv,
A shearing test was conducted under the conditions of an opening gap of 12 mm and a shearing speed of 1.3 m/s. As a result, as shown in Figure 1, the arc portion
It was found that cutting performance is poor even if the IACS is small or large, but good results can be obtained when the IACS is between 10 and 30%. As a material with IACS of 10 to 30% and stronger than Cu,
Carbon steel (e.g. S10C, S45C, SGD3), composite metals containing iron (e.g. Cu-Fe metals known from Japanese Patent Publication No. 44-7838, etc., known from Japanese Patent Publication No. 53-21777, etc.) (Cu-SUS metal) falls under this category. Based on the results shown in Figure 1, the inventors
The arc part was formed from carbon steel (S10C) with an IACS of 10 to 20%, and a shear test was conducted by changing the IACS of the contact part. The test conditions were the same as those under which the results shown in FIG. 1 were obtained. As a result, as shown in Figure 2, the contact area
In the range of IACS less than 20% and more than 60%, the shearing performance decreases rapidly, and IACS of 20 to 60%
It has been found that good results can be obtained within the range of %. The Cu-Cr-Mo alloy that forms the contact part is made by mixing a predetermined amount of Cr and Mo powder of 100 mesh or less, placing a Cu block on top of this powder, and heating it at 1100℃ in a vacuum.
It is formed by heating to the above temperature to form a Cr-Mo skeleton and infiltrating Cu into the skeleton. And Cu−Cr−Mo
As a result of examining IACS by changing the mixing ratio of To obtain a material with IACS of 20-60%, Cu should be 20-80% by weight and Cr should be 5-70% by weight.
It has been found that it is sufficient to set the mixing ratio of 5 to 70% by weight and Mo. The present invention has been achieved based on the experimental results explained above, and in a vacuum interplater in which the contact part and the arc part have electrodes made of different materials, the contact part contains copper, chromium, and molybdenum. The arc part is made of a material that contains iron and has an IACS of 10 to 30%, thereby maintaining low cutting current characteristics and high withstand voltage characteristics. We aim to improve the holding and cutting performance,
The present invention also provides a vacuum interrupter whose electrodes are smaller and lighter. Example (Example 1) The Cu-Cr-Mo alloy forming the contact part was prepared by mixing a predetermined amount of Cr and Mo powder of 100 mesh or less, placing a Cu block on top of this powder, and heating it at 1100°C in vacuum.
It is formed by heating to the above temperature to form a Cr-Mo skeleton and infiltrating Cu into this skeleton. The outer diameter of this material
The contact part was made into a ring shape with an inner diameter of 40φmm and an inner diameter of 20φmm. At the same time, for comparison, Cu−
A contact part made of 0.25Bi alloy was also fabricated. On the other hand, the arc part was made of six spiral-shaped pieces with an outer diameter of 80 mm and was made of S10C material. At the same time, arc parts made of Cu and SUS materials were also fabricated for comparison. Table 1 shows the combinations of materials for the contact portion and arc portion that constitute the electrode.

[Table] The electrodes made of the material combinations shown in Table 1 have the same electrode structure as shown in FIG. , opening gap
A shear break test was conducted under the conditions of 12 mm and a shear break speed of 1.3 m/S. As a result, the results shown in FIG. 3 were obtained. Note that the curves labeled A, A, B, and C in FIG. 3 indicate vacuum interrupters equipped with electrodes labeled A, A, B, and C in Table 1, respectively. Therefore, as shown in FIG. 3, the vacuum interrupter A according to Example 1 has a contact part made of Cu-0.25Bi, which has been commonly used in the past and is said to have good shearing performance.
A large current (approximately 35 kA) equivalent to that of a vacuum interrupter tie with an electrode made of Cu can be easily broken, and the arc can be successfully broken with an arc time of about 0.2 cycles, resulting in dynamic dielectric strength. It can be seen that the area is stable and the area where shearing is possible is expanding. (Example 2) As shown in FIG. 4, an arc portion 12 is provided around the tip of the conductive rod 4, and the contact portion 10 directly engages the tip surface of the conductive rod 4 and is temporarily fixed with a screw 11. The electrode 9 is constructed by integrally joining these members together by brazing. When this electrode 9 was manufactured under the same conditions as in Example 1 and a sheath breakage test was conducted under the same conditions, similar results were obtained.
In the case where the contact part 10 is directly fixed to the tip surface of the conductive rod 4 as in this embodiment-2, when energizing
Since IACS does not involve 10 to 30% arcing, it is advantageous in terms of heat generation prevention. Effects of the Invention Since a material containing Fe and having high strength is used for the arc portion, the electrode can be made smaller and lighter. In addition, although the IACS of the arc part is small at 10 to 30%, it can easily break a large current similar to that of conventional products, and the withstand voltage characteristics of the materials themselves that form the contact part and the arc part are excellent. Combined with these favorable conditions, arcing and breaking can be achieved at short arc times, and dynamic dielectric strength can be stabilized when current is interrupted.

[Brief explanation of drawings]

Figure 1 is a graph showing the relationship between the electrical conductivity of the arc part and the shear breakage current, Figure 2 is a graph showing the relationship between the conductivity of the contact part and the shear breakage current, and Figure 3 is a graph showing the relationship between the conductivity of the arc part and the shear breakage current. Graph showing the relationship between the breakage current and arc time of the vacuum interrupter according to the comparative example, 4th
FIG. 5 is a vertical cross-sectional view of an electrode according to a second embodiment of the present invention, FIG. 5 is a vertical cross-sectional view of an electrode according to a conventional technique, and FIG. 6 is a vertical cross-sectional view of a vacuum interrupter according to a conventional technique. . 4... Conductive rod, 5, 9... Electrode, 6... Vacuum container, 7, 10... Contact part, 8, 12... Arc part.

Claims (1)

[Scope of Claims] 1. A vacuum interrupter in which a pair of electrodes that can be freely connected and separated, each consisting of a contact part and an arc part, are joined to a conductive rod and enclosed in a vacuum container,
The contact part has a conductivity of 20 to 60% IACS and is made of a metal material containing copper, chromium, and molybdenum, and the arc part is made of an iron-containing material that has a conductivity of 10 to 30% IACS. A vacuum interrupter characterized by: 2 The iron-containing material is S10C, S45C or
The vacuum interrupter according to claim 1, characterized in that it is SGD3. 3. The vacuum interrupter according to claim 1 or 2, wherein the contact portion is directly brazed to the conductive rod.