JPH059888B2 - - Google Patents

Description

[Detailed description of the invention]

FIELD OF THE INVENTION The present invention relates to a vacuum interrupter, and more particularly to a vacuum interrupter with magnetically driven electrodes. Prior Art The magnetically driven electrode of a vacuum interrupter drives the arc by the interaction between the arc current and the magnetic field generated by making the current path containing the arc into a reciprocating loop, thereby preventing local stagnation of the arc and reducing the current flow. Generally, as shown in Figure 1, a pair of electrode rods 1 (only one is shown in the figure) are introduced into a vacuum container (not shown) so that they can approach and separate from each other. ) an arc drive section 2 having a plurality of spiral or screw-shaped arc pedals fixed to the inner end of the arc drive section 2; and a ring-shaped or button-shaped contact section 3 protruding from the center of the opposing surface of the arc drive section 2. It is composed of. By the way, the following characteristics are generally required for the electrode material of the vacuum interrupter. (1) High current cutting capacity (2) Excellent dielectric strength (3) Low consumption (4) Small current cutting value (5) Low contact resistance (6) Good welding resistance However, it is not possible to satisfy all the characteristics with a single material, and of course it is not possible even with pure metal, so materials are currently selected depending on the purpose of the vacuum interrupter. Therefore, in the conventional magnetically driven electrode, the arc driving part 2 is made of copper as a single material and satisfies the above characteristics, and the contact part 3 is made for large current. −12131
Cu made by adding bismuth to copper known as
- Made of Bi alloy (e.g. Cu-0.5Bi alloy), or made of copper with tungsten added for high voltage use, known from Japanese Patent Publication No. 54-36121 etc.
It is sometimes formed from a Cu-W alloy (for example, a 20Cu-80W alloy). However, since the tensile strength of copper is as low as approximately 20 Kgf/mm ² , the arc drive unit 2 is made of This results in an increase in its axial direction (vertical direction in FIG. 1) dimension (thickness) and weight. Furthermore, since the tensile strength of copper is low, it is not possible to increase the length of the arc pedal in order to increase the magnetic driving force, resulting in a stagnation in current flow and breaking ability. Furthermore, since copper is soft and its vapor pressure and melting point are approximately between those of other elements, such as tungsten and bismuth, in the case of a high current arc, excessive melting of the arc pedal will cause a large amount of copper to be consumed. There's a problem. In addition, in order to cope with the rise in current and voltage associated with the recent expansion of power systems, there is a demand for electrodes that have both excellent current shedding ability and dielectric strength. Purpose of the Invention The present invention has been made in view of the above-mentioned problems.The purpose of the present invention is to provide a compact, lightweight and durable magnetic material capable of interrupting high voltages and large currents. The present invention provides a vacuum interrupter with a driven electrode. 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 a contact portion and an arc drive portion are provided at the inner end of each electrode rod. In a vacuum interrupter formed by fixing magnetically driven electrodes, the contact portions of each electrode are made of 20 to 70% by weight of copper and 5 to 70% by weight of copper.
chromium and 5 to 70% by weight molybdenum, and the arc drive part is 20% by weight.
~70% by weight copper, 5-40% by weight chromium and 5
It is formed from a composite metal of ~40% by weight iron. Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 2 is a vertical cross-sectional view of a vacuum interrupter showing an embodiment of the present invention. This vacuum interrupter has a pair of electrode rods 5, 5 introduced into a vacuum container 4 so as to be able to approach and separate from each other, and It is generally constructed by fixing magnetically driven electrodes 6, 6 to the inner ends of electrode rods 5, 5, respectively. That is, the vacuum container 4 includes a thin-walled annular sealing fitting 8 made of Fe-Ni-Co alloy, Fe-Ni alloy, etc., to which both ends of two cylindrical insulating tubes 7, 7 made of glass or ceramics are fixed. , 8, . It is formed by evacuating the inside to a high vacuum (for example, a pressure of 5×10 ^-5 Torr or less). Each of the electrode rods 5 is introduced into the vacuum container 4 from the center of each metal end plate 9 so as to be able to approach and separate from each other while maintaining the airtightness of the vacuum container 4. Note that one side of the electrode rod 5 (upper side in Fig. 2)
is airtightly inserted into one metal end plate 9, and the other metal end plate 9 is inserted in the axial direction (Fig. It is inserted so that it can move freely in the vertical direction). Also, in Figure 2, 1
1 and 12 are a shaft shield and a bellows shield, 13 is a main shield, and 14 is an auxiliary shield. As shown in FIG. 3, at the inner end of each electrode rod 5, there is a mounting base 15 made of a highly conductive material such as copper and shaped like a disk and having a diameter suitably larger than the diameter of the electrode rod 5. , are fixed by brazing through a recess 16 formed on one (lower side in FIG. 3) surface. A recess 17 having a suitably larger diameter than the recess 16 on the one surface is formed on the other surface of the mounting base 15 . As well as being formed,
By cutting a plurality of spiral-shaped slits 18 from the periphery to the vicinity of the center in order to magnetically drive the arc, an arc drive section 6a having a plurality of spiral-shaped arc pedals around the periphery is provided protruding from the center of one surface. It is fixed by brazing through the protrusion. This arc driving section 6a forms a magnetically driven electrode 6 in conjunction with a contact section which will be described later. A circular recess 19 having a diameter suitably larger than the diameter of the electrode rod 5 is formed in the center of the other opposing surface of the arc drive section 6a, and a ring-shaped contact section 6b is formed in this recess 19. It protrudes from the opposing surface of the arc drive section 6a and is fixed by brazing. The arc driving section 6a 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, and is made of a composite metal of 20 to 70% by weight of copper, 5 to 40% by weight of chromium, and 5 to 40% of iron. The metal has an electrical conductivity (IACS%) of 5-30%, a tensile strength of 30 Kgf/mm ² or more, and a hardness of 100-170 Hv (1 Kg). Note that the composite metal forming the arc drive section 6a is manufactured by various methods described below. (1) Mix a specified 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 the powder on top of the container. A fixed amount of copper block was placed and then heated to 1000°C in vacuum (5 x 10 Torr).
The copper is heated for 10 minutes at 1100℃, which is higher than the melting point of copper (1083℃), to form a porous base material made of chromium and iron. This is done by infiltrating the base material. (2) Powder chromium and iron, mix them in predetermined amounts, place the 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.), at a temperature 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 copper if the copper material is not placed on the powder in advance). Heat and hold at a temperature below the melting point of the metal (e.g. 600 to 1000
℃ for about 5 to 60 minutes) to form a porous base material, and then heated and held in the above atmosphere above the melting point of copper (for example, at 1100℃ for about 5 to 20 minutes) to form a porous base material. This is done by infiltrating and bonding them together. (3) Powder each metal, mix a predetermined amount of each 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 bonded together by heating and holding (for 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 -60 mesh
Any mesh (250 μm or less) is sufficient. However, when the particle size becomes larger than 60 meshes, it becomes necessary to raise the heating temperature or lengthen the heating time to deal with the increased diffusion distance when diffusion bonding each metal powder particle, which reduces productivity. This will result in a decline. 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 copper 10
consisting of wt% chromium and 40wt% 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 structure of the composite metal (composed of 10% by weight of iron) was as shown in the X-ray photographs shown in FIGS. 4A to D, 5A to D, and 6A to D, respectively. That is, the X-ray photographs A in FIGS. 4, 5, and 6 are secondary electron images, and the X-ray photographs B in each figure show the characteristic X showing the dispersion state of chromium Cr.
In the line image, the gray parts scattered like islands are chrome. Further, the X-ray 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. In addition, the X-ray photograph D in each figure is a characteristic X-ray image showing the dispersion state of copper (Cu), and the white portion is 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. On the other hand, the contact portion 6b contains 20 to 70% by weight of copper,
It is made of a composite metal consisting of 5 to 70% by weight of chromium and 5 to 70% by weight of molybdenum.
Composite metals with this component and composition range are 20-60%
It has an electrical conductivity of 120 to 180 Hv (1 kg) and a hardness of 1 kg. Note that the composite metal forming the contact portion 6b is manufactured by various methods substantially similar to those for forming the arc drive portion 6a, and
Almost the same thing can be said about the particle size of each metal powder. Next, a -A component composition (consisting of 50% by weight of copper, 10% by weight of chromium and 40% by weight of molybdenum) and a -B component composition (consisting of 50% by weight of Copper, 25% by weight
of chromium and 25% by weight of molybdenum)
and -C component composition (50% by weight copper, 40% by weight
of chromium and 10% by weight of molybdenum)
The structural states of the composite metals are shown in Figure 7A~
D, the result looked like the X-ray photographs shown in FIGS. 8A-D and 9A-D. That is, the X-ray photographs A in FIGS. 7, 8, and 9 are secondary electron images, and the X-ray photographs B in each figure are characteristic X showing the dispersion state of chromium Cr.
In the line image, the gray or white parts scattered like islands are chromium. Further, the X-ray photograph C in each figure is a characteristic X-ray image showing the dispersion state of molybdenum Mo, and the gray parts scattered like islands are molybdenum. Furthermore, the X-ray photograph D in each figure is a characteristic X-ray image showing the dispersion state of copper (Cu), with the white portion being copper. Therefore, the chromium and molybdenum particles are diffusely bonded to each other to form a porous substrate.
Moreover, it can be seen that copper is infiltrated into the pores (voids) of this base material, creating a strongly bonded composite metal. Further, a composite metal having a -A component composition, a -B component composition and a -C component composition forms the arc driving part 6a, and a composite metal having a -A component composition, a -B component composition and a -C component composition forming the contact part 6b. The test results for various properties of the metal were as described below. Note that A indicates the characteristics of the composite metal forming the arc drive portion 6a, and B indicates the characteristics of the composite metal forming the contact portion 6b. (1) Electrical conductivity (IACS%) A; 8-10% B; 40-50% (2) Tensile strength A; 30Kgf/mm ² (3) Hardness A; 100-170Hv (1Kg), B; 120-180Hv
(1Kg) Both are sufficiently hard compared to copper's approximately 40Hv (1Kg). Furthermore, the arc driving part 6a is made of a composite metal with a -B component composition and has a diameter of 100 m/m and has eight arc pedals, and the contact part 6b is made of a composite metal with a -A component composition and has an inner diameter of 30 m/m.
Verification of various performances was carried out by forming the electrode 6 shown in Fig. 3 into a ring shape with an outer diameter of 60 m/m and incorporating this pair of electrodes 6 as a vacuum interrupter shown in Fig. 2. The results were as described below. (1) Current shedding capacity Rated voltage with shedding speed 1.2 to 1.5 m/s
When we conducted a shearing test at 12kv (re-electromotive voltage 21kv, JEC-181), we were able to cut off a current of 45kA (r, m, s). In addition, the rated voltage was 84kv (restart voltage
When we conducted a shearing test at 143kv (JEC-181), we were able to cut a current of 35kA (r, m, s). Note that -A forming the arc drive section 6a,
-A, -B and - forming the contact portion 6b with composite metals having component compositions -B and -C
Table 1 shows the current shedding ability of the invented product in various combinations with composite metals having the C component composition, and the current shedding ability of comparative products and conventional products tested under the same conditions.

【table】

[Table] (2) Dielectric strength When the gap was maintained at 30m/m and a shock wave withstand voltage test was performed, the result was ±250kv (variation ±
It showed a dielectric strength of 10kv). In addition, similar tests were conducted after multiple cycles of high current (45kA) and after interruptions, but there was no change in dielectric strength. A similar test was conducted after a small current (80A) was applied, but there was almost no change in dielectric strength. Note that the dielectric strength of the combination of the arc driving part 6a and the contact part 6b made of composite metals of each component composition has the same value as that of the combination of composite metals of -B component composition and -A component composition. Indicated. Further, Table 2 shows the comparison results of the shock wave withstand voltage test between the product of the present invention (a combination of the -B component composition and the -A component composition), comparative products, and conventional products.

【table】

[Table] (3) Welding resistance Under a pressure of 130 kg, a current of 25 kA (rms) is
After applying current for seconds (IEC short-time current standard),
It can be removed without any problem with a static removal force of 200Kg, and the increase in contact resistance after that is 2 to 2.
It remained at 8%. In addition, there is no problem with tripping after applying a current of 50 kA (rms) for 3 seconds under a pressure of 1000 kg, and the increase in contact resistance after that is only 0 to 5%, providing sufficient welding resistance. Ta. Note that similar results were obtained when the contact portion 6b was made of a composite metal having a -B or -C component composition. (4) Ability to withstand small delayed currents (inductive loads) The average current interruption value obtained when a current of 30 A is applied is 3.9 A (standard deviation σn = 0.96, number of samples n =
100). In addition, when the contact part 6b is made of a composite metal with a -B component composition, the average resistance is 3.7A (σn=1.26, n=
100), and when formed from a composite metal with a -C component composition, an average of 3.9A (σn = 1.5, n = 100)
The current cutoff value was shown. (5) Ability to withstand small leading current (capacitive load) Voltage: 84 kv x 1.25/√3, 80 A small leading current test (JEC-181) was conducted 10,000 times, but there was no restrike. It was hot. Incidentally, the same was true when the contact portion 6b was made of a composite metal having a -B or -C component composition. However, if the component composition range of the composite metal forming the arc driving part 6a 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 The advantages of the elements were not fully utilized, and the current carrying capacity, dielectric strength, mechanical strength, etc. were significantly reduced. That is, if the copper content is less than 20% by weight,
When the content of chromium exceeds 70% by weight, the mechanical strength and dielectric strength significantly decrease, and when the content of chromium is less than 5% by weight, the dielectric strength decreases significantly. On the other hand, when the content exceeded 40% by weight, the mechanical strength significantly decreased. Furthermore, if the iron content is less than 5% by weight,
The mechanical strength was significantly reduced, and when it exceeded 40% by weight, the current carrying and cutting ability was significantly reduced. In addition, if the component composition range of the composite metal forming the contact portion 6b is other than 20 to 70% by weight of copper, 5 to 70% by weight of chromium, and 5 to 70% by weight of molybdenum, the advantages of each component element Therefore, it was not possible to satisfy each characteristic required of the contact portion 6b. That is, when copper is less than 20% by weight, the conductivity decreases and the contact resistance increases significantly, while when it exceeds 70% by weight, the welding resistance decreases and the current cutoff value increases significantly. In addition, the dielectric strength decreased significantly. Furthermore, when the content of chromium was less than 5% by weight, the dielectric strength decreased significantly, while when it exceeded 70% by weight, the electrical conductivity and mechanical strength decreased significantly. Furthermore, when the molybdenum content was less than 5% by weight, the dielectric strength decreased significantly, while when it exceeded 70% by weight, the mechanical strength decreased significantly and the current cutoff value increased significantly. Effects of the Invention As described above, according to the present invention, the arc drive section can be
~70% by weight copper, 5-40% by weight chromium, 5
It is formed of a composite metal consisting of ~40% by weight of iron, and the contact part is made of a composite metal consisting of 20~70% by weight of copper and 5~40% by weight of copper.
Since it is made of a composite metal consisting of 70% by weight chromium and 5 to 70% by weight molybdenum, the arc driving part is made of copper and the contact part is made of copper.
Compared to conventional ones made of -0.5Bi alloy or 20Cu-80W alloy, various effects described below are achieved. (1) By improving the tensile strength of the arc drive part, the thickness and weight of the electrode can be significantly reduced. (2) By increasing the tensile strength of the arc drive part, the length of the arc pedal can be increased without changing its outer diameter, and the magnetic drive force can be significantly increased. (3) Since the arc drive part and the contact part are made of a composite metal with high hardness and uniformly dispersed components, excessive melting of the arc pedal and the contact part can be prevented and wear and tear can be significantly reduced. At the same time, the dielectric recovery characteristics can be improved, and there is almost no decrease in dielectric strength after 10,000 cycles or rupture. 10-20%)
be able to. Furthermore, the current cutoff value can be reduced. (4) In particular, while keeping the dielectric strength to the same level as the contact part made of 20Cu-80W alloy,
-0.5Bi alloy can cut a much larger current than one in which the contact portion is formed.

[Brief explanation of the drawing]

Figure 1 is a vertical cross-sectional view of a conventional magnetically driven electrode.
FIG. 2 is a vertical cross-sectional view of a vacuum interrupter showing an embodiment of the present invention, and FIG. 3 is a vertical cross-sectional view of its electrodes.
Fig. 4 A, B, C, D, Fig. 5 A, B, C, D, and Fig. 6 A, B, C, D respectively show the structural states of different compositions of the composite metal forming the arc driving part. X-ray photographs, Fig. 7 A, B, C, D, Fig. 8 A, B, C, D, and Fig. 9 A, B, C, D show the structures of different compositions of the composite metal forming the contact area, respectively. This is an X-ray photograph showing the condition. 4... Vacuum container, 5... Electrode rod, 6... Electrode,
6a... Arc drive section, 6b... Contact section.

Claims (1)

[Claims] 1 A pair of electrode rods are introduced into a vacuum container so that they can approach and separate from each other, and a magnetically driven electrode consisting of a contact part and an arc drive part is fixed to the inner end of each electrode rod. In the vacuum interrupter, the contact portion of each electrode is coated with 20 to 70% by weight of copper,
It is made of a composite metal of 5-70% by weight of chromium and 5-70% by weight of molybdenum, and the arc drive part is made of a composite metal of 20-70% by weight of copper, 5-40% by weight of chromium and 5-40% by weight of iron. A vacuum interrupter characterized in that it is formed from a composite metal.