JPH0432487B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a vacuum interrupter, and more particularly to improvement of an electrode in a so-called longitudinal magnetic field type vacuum interrupter, which is equipped with means for generating an axial magnetic field (longitudinal magnetic field) parallel to an arc. Prior art Vertical magnetic field type vacuum interrupters apply a parallel vertical magnetic field to the arc to disperse the arc on the electrode surface and prevent its local concentration, thereby preventing excessive melting of the electrode. A pair of electrode rods are introduced into a vacuum container so that they can be moved toward and away from each other, and an arc diffusion part and a contact part are installed at the inner end of each electrode rod. and a coil as a longitudinal magnetic field generating means is provided outside the vacuum container as described in Japanese Patent Publication No. 42-13045, or Japanese Patent Publication No. 53-41783. ,
Special Publication No. 54-22813 or Japanese Patent Application Publication No. 1983-
As described in Japanese Utility Model Publication No. 130037, etc., it is possible to provide the back of each electrode in a vacuum container, or furthermore, as described in Japanese Utility Model Application Publication No. 56-57443, etc., a pair of electrodes in a vacuum container can be provided. It is arranged around the outer periphery. Therefore, in the electrodes of the conventional vertical magnetic field type vacuum interrupter, the arc diffusion part is formed of copper, and in order to suppress the eddy current generated due to the linkage of the vertical magnetic field in this arc diffusion,
A plurality of radial slits are provided as described in Japanese Patent No. -52562 and the like. However, due to the low tensile strength of copper, approximately 20 Kgf/ ^mm2 , and the fact that it is provided with multiple slits, the arc diffusion section is susceptible to shocks at the time of injection and extinguishing, as well as the electromagnetic force of the large current arc. In order to prevent deformation due to impacts and the like caused by this, the axial dimension (thickness) and weight have increased. In addition, the arc and electric field concentrate at the edge of the slit, reducing the current shearing ability and dielectric strength, especially the dielectric strength after shearing (dynamic dielectric strength), and causing a large amount of wear on the arc diffusion area. There is a problem. In addition, the contact part is for high current and low voltage
-Cu-Bi alloy containing minute amounts of bismuth in copper (for example, Cu
-0.5Bi alloy), or copper containing tungsten as described in Japanese Patent Publication No. 54-36121 for low current and high voltage.
It is made of W alloy (for example, 20Cu-80W alloy). Purpose of the Invention The present invention has been made in view of the above-mentioned problems, and its purpose is to provide a vertical magnetic field system equipped with electrodes that can be made compact and lightweight, and that can improve current cutting ability and durability. To provide a vacuum interrupter. Structure of the Invention In order to achieve the above object, the present invention introduces a pair of electrode rods into a vacuum container so that they can approach and separate from each other freely, and an arc diffusion part and a contact part are provided at the inner end of each electrode rod. A vacuum interrupter comprising a coil for applying an axial magnetic field parallel to the arc to the outside of the vacuum vessel or inside the vacuum vessel, wherein at least an arc diffusion portion of each of the electrodes is fixedly fixed to the vacuum interrupter. It is made of a composite metal of 20-70% by weight copper, 5-40% chromium and 5-40% iron. Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal cross-sectional view of a vacuum interrupter showing an embodiment of the present invention, and this vacuum interrupter is arranged in a vacuum container 1 on its axis, and a pair of electrode rods 2, 2 are placed relatively close to each other. A pair of electrodes 3, 3 in the shape of a hat-shaped disk are mechanically fixed to the inner end of each electrode rod 2 with an insulating spacer interposed, and each electrode rod 2 and electrode 8 are connected to each other as electrodes. a coil 4, which is disposed on the back of the electrode rod 8 and generates a vertical magnetic field by changing the axial current flowing through the electrode rod 2 (vertical direction in FIG. 1) into a loop current centered around the electrode rod 2;
4 and is electrically connected to each other. That is, the vacuum container 1 includes a thin annular sealing fitting 6 made of Fe-Ni-Co alloy, Fe-Ni alloy, etc., with two cylindrical insulating tubes 5, 5 made of glass or ceramics fixed to both ends. , 6, . It is formed by evacuating the inside to a high vacuum (for example, a pressure of 5×10 ^-5 Torr or less). The electrode rods 2 are introduced into the vacuum container 1 from the center of each metal end plate 7 so as to be able to approach and separate from each other while maintaining the airtightness of the vacuum container 1. In addition, one (upper in FIG. 1) electrode rod 2
is airtightly inserted into one metal end plate 7, and the other electrode rod 2 is inserted into the other metal end plate 7 as an axis while maintaining the airtightness of the vacuum vessel 1 via a metal bellows 8. It is inserted so that it can move freely in any direction. Further, in FIG. 1, 9 and 10 are a shaft shield and a bellows shield, 11 is a main shield, and 12 is an auxiliary shield. As shown in FIGS. 2 and 8, the inner end of each electrode rod 2 is made of a highly conductive material such as copper and has a disc-shaped diameter suitably larger than the diameter of the electrode rod 2. A mounting base 4a, two arms 4b extending outward in the radial direction (in the left-right direction in FIG. 2) from opposing positions on the outer periphery of the mounting base 4a, and two arms 4b extending outward from the end of each arm 4b with the mounting base 4a as the center. A 1/2 shunt type coil 4 consisting of a circular arc portion 4c curved in an arc shape in the same direction is attached to the mounting base 4a.
It is fixed by brazing through a recess 13 formed in one (lower side in FIG. 2) of the surface. The coil 4 includes a ring-shaped attachment part 14a fitted to the outer circumference of the inner end of the electrode rod 2 by brazing, and a plurality of support arms 14b extending radially outward from the outer circumference of the attachment part 14a. It is reinforced by brazing with a coil reinforcing body 14 consisting of a ring-shaped support part 14c connecting the ends of each support arm 14b. The coil reinforcing body 14 is made of a material with high mechanical strength and low electrical conductivity, such as stainless steel. A circular recess 15 is provided on the other surface of the mounting base 4a of the coil 4, and the recess 15 is made of a material with high mechanical strength and low conductivity, such as stainless steel or Inconel. An insulating spacer 16 formed in a cylindrical shape is fixed by brazing via a small diameter flange 16a formed at one end thereof. The large-diameter flange 16b formed at the other end of the insulating spacer 16 is fitted with a circular plate-shaped mounting having a diameter appropriately larger than that of the large-diameter flange 16b and having a through hole approximately the same diameter as the inner diameter of the insulating spacer 16. A base 17a, two arms 17b extending radially outward from opposing positions on the outer periphery of the mounting base 17a, and a radius of curvature approximately equal to the arcuate portion 4c of the coil 4 from the end of each arm 17b. The auxiliary coil 1 consists of a circular arc portion 17c curved in an arc shape with an appropriate length in the same direction opposite to this, and is made of a material with high conductivity such as copper.
7 is fixed by brazing via an engagement step 18 provided on one (lower side in FIG. 2) surface of the mounting base 17a. The auxiliary coil 17 and the coil 4 are each circular arc portion 17c of the auxiliary coil 17.
One end is fixed to a recess 19 provided at the end of the coil 4, and the other end is electrically connected via an axial current-carrying pin 20 inserted into a through hole 21 provided at the end of each arcuate portion 4c of the coil 4. has been done. The electrode 3, which is formed to have approximately the same diameter as the coil 4, is attached to the auxiliary coil 17 by brazing to the mounting base 17a through a recess 22 provided at the center of the back surface.
It is joined to each arm 17b and arc portion 17c via the back surface by brazing. Electrode 3 is on the opposing surface (upper surface in FIG. 2)
The arc diffusion part 3a is formed in the shape of a cap-shaped disk with a circular recess 23 in the center and gradually becomes thinner as it approaches the periphery, and has a flat circular contact surface on the opposing surface and becomes gradually thinner as it approaches the periphery. The arc diffusion part 3 is formed in a cap-shaped disk shape and
Contact portion 3 fixed to recess 23 of a by brazing
b, and is provided in the shape of a cap-shaped disk as a whole. The arc diffusion part 3a of the electrode 3 is formed of a composite metal consisting of 20 to 70% by weight of copper, 5 to 40% by weight of chromium, and 5 to 40% by weight of iron. Composite metals in the range 5-
It has an electrical conductivity (IACS%) of 30%, a tensile strength of 30 Kgf/mm ² or more, and a hardness of 100 to 170 Hv (1 Kg). Further, the contact portion 3b is made of a conventional Cu-Bi alloy (for example, Cu-0.5Bi alloy) or Cu-W alloy (for example, 20Cu-80W alloy). Note that the composite metal forming the arc diffusion portion 3a is manufactured by various methods described below. (1) For example, mix a predetermined amount of -100 mesh chromium powder and -100 mesh iron powder, place this mixed powder in a container made of a material that does not react with chromium, iron, and copper (such as alumina), and place it on top of the container. A predetermined amount of copper block is placed on it, and after it is burnt, it is first heated at 1000℃ for 10 minutes in a vacuum (5 x 10 ^-5 Torr) to degas it, and a porous base material made of chromium and iron is removed. form,
Next, the temperature is 1100℃, which is higher than the melting point of copper (1083℃).
The copper is infiltrated into the porous substrate by heating for 10 minutes. (2) Powder chromium and iron, mix them in a predetermined amount, place this mixed powder in a container made of alumina, etc., and place it in a non-oxidizing atmosphere (for example, in a vacuum, hydrogen gas, nitrogen gas, or argon gas). gas, etc.), below the melting point of each metal (for example, below the melting point of copper if the copper material is placed on the powder in advance, or below the melting point of the other metal if the copper material is not placed on the powder in advance). Heating and holding at a temperature below the melting point (e.g. 600 to 1000℃)
(for about 5 to 60 minutes) to form a porous base material, and then heated and held above the melting point of copper in the above atmosphere (for example, at 100°C for about 5 to 20 minutes) to coat copper on this base material. Performed by infiltration and integral bonding. (3) Powder each metal, mix a predetermined amount of the required metal powder, press-mold this mixed powder to form a mixed element, and then place the mixed element in a non-oxidizing atmosphere at the melting point of copper. The metal powder particles are integrally bonded by heating and holding (about 5 to 60 minutes) at a temperature below (for example, 1000°C) or above the melting point of copper and below the melting point of other metals (for example, 1100°C). Here, the particle size of the metal powder is not limited to -100 mesh (149 μm or less), but may be -60 mesh (250 μm or less). However, the particle size
If the size is larger than 60 meshes, when diffusion bonding each metal powder particle, it is necessary to increase the heating temperature or lengthen the heating time to cope with the increased diffusion distance, which may reduce productivity. Become. On the other hand, as the upper limit of the particle size decreases, uniform mixing (uniform dispersion of each metal powder particle) becomes difficult, and it is easy to oxidize, making handling troublesome and requiring pretreatment before use. Because of these problems, there is a limit, and the upper limit of the particle size is selected based on various conditions. Further, in both of the above-mentioned manufacturing methods 2 and 3, a vacuum atmosphere is preferable as the non-oxidizing atmosphere since it has the advantage that degassing can be performed simultaneously during heating and holding. However, even when manufactured in a non-oxidizing atmosphere other than a vacuum atmosphere, there is no difference in performance as an electrode for a vacuum interrupter. Next, the -A component composition (50% by weight of copper,
consisting of 10% chromium and 40% iron),
-B component composition (consisting of 50% by weight copper, 25% by weight chromium and 25% by weight iron) and -C component composition (consisting of 50% by weight copper, 40% by weight chromium and
The structural states of the composite metals (10% iron) are shown in Figures 4A-D, 5A-D, and 6A-D, respectively.
The characteristics are as shown in the photo. That is, the photographs A in Figures 4, 5, and 6 are secondary electron images, and the photographs B in each figure are characteristic X-ray images showing the dispersed state of chromium Cr, which is island-shaped. The scattered gray parts are chrome. Further, the photograph C in each figure is a characteristic X-ray image showing the dispersion state of iron (Fe), and the white or gray parts scattered like islands are iron. The photograph D in each figure is a characteristic X-ray image showing the dispersion state of copper, with the white portion being copper. Therefore, the chromium and iron particles are diffusely bonded to each other to form a porous base material, and copper is infiltrated into the pores (voids) of this base material to form a strongly bonded composite metal. It can be seen that this is the case. Further, the test results of the component composition, component composition, and various properties of the composite metal of the component composition forming the arc diffusion portion 3a were as described below. (1) Electrical conductivity (IACS%) 8-10% (2) Tensile strength 80Kgf/mm ² or more (3) Hardness 100-170Hv (1Kg) Sufficiently hard compared to copper's approximately 40Hv (1Kg). (4) Dielectric strength A pair of circular disks with a diameter of 100 m/m and a thickness of 6.5 m/m are placed facing each other with a gap of 3 m/m under a pressure of 5 × 10 ^-5 Torr to resist shock waves. A voltage test showed a dielectric strength of ±120kV. Furthermore, the arc diffusion part 3a is formed into a cap-shaped disk shape with a diameter of 100 m/m by using a composite metal with a component composition, and the contact part 3b is formed into a cap-shaped disc shape with a diameter of 60 m/m by using a 20Cu-80W alloy or a Cu-0.5Bi alloy. The electrodes 3 shown in FIG. 2 were formed into a plate shape, and the pair of electrodes 3 were incorporated into the vacuum interrupter shown in FIG. 1. The results of verification of current shedding ability and dielectric strength were The arc diffusion part is made of copper in the shape of a cap-shaped disk with a diameter of 100 m/m and has six slits, and the contact part is made of 20Cu-80W alloy or Cu-0.5Bi alloy into a cap-shaped circle with a diameter of 60 m/m. The results are shown in the table below, which also shows the verification results under the same conditions for a conventional one formed into a plate shape.

[Table] In addition, the current shearing ability is at a shearing speed of 1.2~
1.5m/s, rated voltage 12kV (restart voltage
12kV, JEC-181) and a rated voltage of 84kV (re-electromotive voltage 143kV, JEC-181), and the dielectric strength was determined by a shock wave voltage test in which the gap was maintained at 30m/m and a shock wave was applied. . In addition, values similar to those obtained when the arc diffusion portion 3a was formed of a composite metal having a component composition and a composite metal having a component composition were shown. In addition, the number of times the conventional product can withstand tearing is 10,000 times, compared to 500 times for the conventional product, which is a dramatic increase. However, if the component composition range of the composite metal forming the arc diffusion part 3a is outside the range of 20 to 70% by weight of copper, 5 to 40% by weight of chromium, and 5 to 40% by weight of iron, each component element However, the advantages of this method were not fully utilized, and there was a significant decrease in current cutting ability, dielectric strength, mechanical strength, etc. That is, if the copper content is less than 20% by weight,
The current shedding ability was significantly reduced, and when it exceeded 70% by weight, the mechanical strength and dielectric strength were significantly reduced, and the electrical conductivity was increased, resulting in a decrease in the current shedding ability. In addition, when chromium is less than 5% by weight, the electrical conductivity increases and the ability to pass and break current decreases, as well as the dielectric strength decreases significantly, while when it exceeds 40% by weight, the mechanical strength significantly decreases. decreased. Furthermore, iron is 5% by weight.
When the amount was less, the mechanical strength decreased significantly, while when it exceeded 40% by weight, the current cutting ability decreased significantly. FIG. 7 is a longitudinal cross-sectional view of the main parts of a vacuum interrupter showing another embodiment of the present invention, and this embodiment has the following features:
In the above-described embodiment, the arc diffusion section 3a and the contact section 3b are each formed into a hat-shaped disk shape using different materials, whereas the arc diffusion section 3
A is formed into a hat-shaped disk shape with a composite metal having an electrical conductivity of 20 to 30% and consisting of 20 to 70% by weight of copper, 5 to 40% by weight of chromium, and 5 to 40% by weight of iron. In addition, a flat circular surface formed on the opposing surface of the arc diffusion section 3a is used as a contact section 3b, and the same effects as those of the above-mentioned embodiments are achieved. Note that the other configurations are the same as those of the embodiment described above, so the same reference numerals are given and the explanation thereof will be omitted. The electrical conductivity of the composite metal in each of the examples described above varies depending on the heating holding time during infiltration of copper into a porous base material made of chromium and iron. Furthermore, in each of the embodiments described above, the coil 4
I mentioned the case where is a 1/2 branch type, but
The coil 4 is not limited to this, and may be, for example, one turn, 1/3 shunt type, or 1/4 shunt type. Furthermore, the electrical connection between the electrode 3 and the coil 4 is not limited to the case where the auxiliary coil 17 bonded to the back of the electrode 3 is used.
For example, as described in Japanese Patent Publication No. 58-41783, one end of the coil may be directly connected to the center of the back surface of the electrode. In addition, the coil 4 is not limited to being disposed on the back of the electrode 3; for example, the coil may be disposed so as to surround a pair of electrodes as described in Japanese Utility Model Application Publication No. 56-57443, etc. Of course, the coil may be disposed outside the vacuum container as described in Japanese Patent Publication No. 42-13045. Effects of the Invention As described above, according to the present invention, at least the arc diffusion portion of the electrode is made of 20 to 70% by weight of copper and 5% by weight of copper.
Formed by a composite metal consisting of ~40% by weight chromium and 5-40% by weight iron, and composite metals with this composition and composition range have an electrical conductivity of 5-30% (IACS%)
As a result, the arc diffusion part is made of copper, and compared to the conventional structure in which multiple slits are provided in the arc diffusion part to suppress the generation of eddy current, various effects described below can be achieved. play. (1) The thickness and weight of the electrode can be significantly reduced by improving the tensile strength of the arc diffusion part. (2) Due to the low conductivity of the arc diffusion part,
The generation of eddy current can be significantly reduced, and there is no need to provide slits, so
The effect of (1) above can be further promoted, and the current cutting ability can be greatly improved. (3) The arc diffusion part is made of a composite metal with high hardness and uniformly dispersed components, which together with the fact that there are no slits in the arc diffusion part prevents excessive melting of the arc diffusion part. This can significantly reduce consumption.

[Brief explanation of drawings]

FIG. 1 is a vertical sectional view of a vacuum interrupter showing one embodiment of the present invention, FIGS. 2 and 3 are longitudinal sectional views and exploded perspective views of the main parts thereof, and FIGS. 4A, B, C, and D. , Fig. 5 A, B, C, D and Fig. 6 A, B, C, D, respectively, are characteristic photographs showing the structure states of different compositions of the composite metal forming the arc diffusion part, and Fig. 7 is the characteristic photograph of the structure of the composite metal of the present invention. It is a longitudinal cross-sectional view of the principal part of the vacuum interrupter which shows another Example. 1... Vacuum container, 2... Electrode rod, 3... Electrode,
3a...Arc diffusion part, 3b...Contact part, 4...
coil.

Claims (1)

[Claims] 1 A pair of electrode rods are introduced into a vacuum container so as to be able to approach and separate from each other, and an electrode consisting of an arc diffusion part and a contact part is fixed to the inner end of each electrode rod, and the outside of the vacuum container is Alternatively, in a vacuum interrupter comprising a coil for applying an axial magnetic field parallel to the arc inside a vacuum vessel, at least the arc diffusion portion of each electrode is made of 20 to 70% by weight copper and 5 to 40% by weight. A vacuum interrupter formed of a composite metal of chromium of