JPH0510778B2 - - 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 more particularly to a so-called vertical magnetic field type vacuum interrupter that 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 the vacuum container so that they can be moved toward and away from each other, and the inner end of each electrode rod is separated from the arc diffusion part and the contact part. A coil as a longitudinal magnetic field generating means is provided outside the vacuum vessel as described in Japanese Patent Publication No. 42-13045, or as described in Japanese Patent Publication No. 53-41793, Publication No. 54-22813 or Japanese Patent Application Publication No. 56-130037
As described in the publication, etc., it is necessary to provide the back of each electrode in the vacuum container, and even
As described in Japanese Patent Publication No. -57443, etc., it is arranged around a pair of electrodes in a vacuum container. Incidentally, the electrode material of the vacuum interrupter is required to have the following properties (i) to (vi). (i) High current breaking ability (ii) High withstand voltage (iii) Low consumption (iv) Low current cutting value (v) Low contact resistance (vi) Low welding force As disclosed in, for example, Japanese Utility Model Application Publication No. 57-89242, some conventional vertical magnetic field type vacuum interrupter electrodes have an arc diffusion section and a contact section made of stainless steel. Such an electrode can suppress the generation of eddy current generated in the electrode due to a longitudinal magnetic field, and has high mechanical strength.
However, if stainless steel, which has low conductivity and high mechanical strength, is also used for the contact part, the above
Characteristics (iv), (v) and () cannot be obtained. Therefore, the arc diffusion part was formed of stainless steel, and the contact part was made of a Cu-Bi alloy (e.g. Cu
-0.5Bi alloy) is known. However, although such electrodes have excellent large current interrupting ability, welding resistance, and contact resistance, they are unsuitable for high voltage applications. In addition, for high voltage applications, the arc diffusion part is made of stainless steel, and the contact part is made of a Cu-W alloy (e.g. 20Cu-80W alloy) is known. However, this electrode has the disadvantage that it is difficult to interrupt large currents such as fault currents. On the other hand, in order to cope with the rise in current and voltage accompanying the recent expansion of power systems, there is a demand for electrodes with excellent current interrupting ability and dielectric strength. OBJECTS OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a vertical magnetic field type vacuum interrupter equipped with electrodes capable of interrupting large currents and high voltages. 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, and an arc diffusion part and a contact part are provided at the inner end of each electrode rod. Each electrode consisting of is fixed,
In 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, the arc diffusion portion of each electrode is formed of austenitic stainless steel, Contact area copper 20~70
wt%, chromium 5-70 wt% and molybdenum 5
It is formed from a composite metal consisting of ~70% by weight. 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 cap-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 3 are connected to each other as electrodes. a coil 4, which is disposed on the back of the electrode rod 3 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 is a thin-walled annular sealing fitting made of Fe-Ni-Co alloy, Fe-Ni alloy, etc., with two cylindrical insulating tubes 5, 5 made of glass or ceramics fixed at both ends. 6, 6, . . . are joined together to form a single insulating cylinder, and both open ends thereof are closed by disc-shaped metal end plates 7, 7 through the other sealing fittings 6, 6, and high vacuum inside (for example, pressure below 5×10 ^-5 Torr)
It is formed by exhausting the air. And vacuum container 1
Inside, the electrode rod 2 is introduced from the center of each metal end plate 7 so as to be able to approach and separate from the vacuum container 1 while maintaining its airtightness. 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 the 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. At the inner end of each electrode rod 2, as shown in FIGS. 2 and 3, there is a disc-shaped disc made of a material with high conductivity such as Cu and having a diameter suitably larger than the diameter of the electrode rod 2. a mounting base 4a; two arms 4b extending outward in a radial direction (left-right direction in FIG. 2) from opposing positions on the outer periphery of the mounting base 4a;
A 1/2 shunt type coil 4 consisting of an arc portion 4c curved in an arc shape in the same direction with the mounting base 4a as the center from the end of each arm 4b is attached to the mounting base 4.
It is fixed by brazing through a recess 13 formed on one (lower side in FIG. 2) of the surface of the a. 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 portion 3a of the electrode 3 is made of austenitic stainless steel, such as SUS304 or 316L. Note that this stainless steel has an electrical conductivity (IACS%) of 2 to 3%, a tensile strength of 49 Kgf/mm ² or more, and a hardness of 200 Hv (1 Kg). In addition, the contact portion 3b contains 20 to 70% by weight of Cu, 5 to 70% by weight of chromium (Cr), and molybdenum (Mo).
It is formed from 5 to 70% by weight of composite metal.
Furthermore, this composite metal has a conductivity of 20-60% and
It has a hardness of 120-180Hv (1Kg). On the other hand, the composite metal forming the contact portion 3b is manufactured by various methods described below. (1) For example, mix a predetermined amount of -100 mesh Cr powder and -100 mesh Mo powder, place this mixed powder in a container made of a material that does not react with Cr, Mo, and Cu (e.g., alumina), and place it on top of the container. Place the Cu block in a vacuum (5x
10 ^-5 Torr), the melting point of Cu (1083
Cu by heating at 1100℃ for 10 minutes at a temperature above ℃)
This is done by infiltrating a porous base material. (2) Powder Cr and Mo, 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, etc.) at a temperature below the melting point of each metal (for example, below the melting point of Cu if the Cu material is placed on the powder in advance, or Cr if the Cu material is not placed on the powder in advance). (below the melting point of
~60 minutes) to form a porous base material, and then heated and held above the melting point of Cu in the above atmosphere (for example, at 1100°C for about 5 to 20 minutes) to infiltrate Cu into this base material. Combine them as one. (3) Powder Cu, Cr, and Mo metals, mix them in predetermined amounts, press-mold this mixed powder to form a mixed element body, and then place this mixed element body in a non-oxidizing atmosphere. Cu
below the melting point of Cu (e.g. 1000℃) or above the melting point of Cu and below the melting point of other metals (e.g. 1100℃)
The metal powder particles are bonded together by heating and maintaining the temperature (about 5 to 60 minutes) at a temperature of 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, when the particle size is larger than 60 meshes, it becomes necessary to increase the heating temperature or lengthen the heating time as the diffusion distance increases 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 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. Since there are problems such as smearing, etc., there is naturally 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 a 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 I component composition (Cu50% by weight, Cr10% by weight and Mo40% by weight) produced by production method (1),
Ingredient composition (Cu50wt%, Cr25wt% and
Mo25% by weight) and component composition (Cu50% by weight,
The structural states of each composite metal (Cr40% by weight and Mo10% by weight) are shown in Figures 4A to D and Figures 5A to 5, respectively.
D and the X-ray photographs shown in FIGS. 6A to 6D. That is, FIG. 4A, FIG. 5A, and FIG. 6A.
The X-ray photographs in Figure B are secondary electron images, and the X-ray photographs in each figure B are characteristic X-ray images showing the dispersion state of Cr, and the white parts scattered like islands are Cr. In addition, each X-ray photograph in Figure C shows the characteristic X that shows the dispersion state of Mo.
In the line image, the white parts scattered like islands are Mo.
Furthermore, the X-ray photographs in each figure D are characteristic X-ray images showing the dispersion state of Cu, with the white portion being Cu. Therefore, Cr and Mo particles diffusely bond with each other to form a porous base material, and Cu 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 test results of the I component composition, component composition, and various properties of the composite metal of the component composition forming the contact portion 3b were as follows. (1) Electrical conductivity (IACS%) 40-50% (2) Hardness 120-180Hv (1Kg) In addition, the arc diffusion part 3a is formed from austenitic stainless steel SUS304 into a cap-shaped disk shape with a diameter of 100m/m. At the same time, the contact portion 3b is made of a composite metal having an I-component composition and formed into a cap-shaped disk shape with a diameter of 60 m/m to form the electrode 3 shown in FIG. The results of various performance verifications conducted for the vacuum interrupter shown in the figure are as follows. (1) Current interrupting ability The interrupting conditions are rated voltage 12kV (restart voltage 21kV,
JEC-181), 61kA when the cutoff speed is 1.2 to 1.5m/s
(rms) current could be interrupted. Also,
It was possible to interrupt a current of 42 kA (rms) at a rated voltage of 84 kV (restart voltage 143 kV, JEC-181) and a interrupt speed of 3.0 m/s. In addition, when the contact portion 3b was made of a composite metal of each component composition and a comparative product, the current interrupting ability was tested under the same conditions as shown in Table 1.

[Table] (2) Dielectric strength When the gap was maintained at 30m/m and a shock wave withstand voltage test was performed, the result was ±400kV (variation ±10kV)
It showed a dielectric strength of . In addition, similar tests were conducted after cutting off a large current (61kA) many times, but there was no change in dielectric strength. In addition, advance small current (80A)
A similar test was conducted after the circuit was cut off, but there was almost no change in dielectric strength. In addition, the dielectric strength when the contact portion 3b is made of each composite metal of component composition and component composition is I
It showed a value similar to that of the component composition. Table 2 shows the results of shock wave withstand voltage tests for the product of the present invention (combination of SUS304 and I component composition) and the comparative product.

[Table] (3) Welding resistance Under a pressure of 130 kg, a current of 25 KA (rms) was
After energizing for seconds (IEC short-time current standard), 200
The contact resistance could be removed without any problems using a static removal force of Kg, and the subsequent increase in contact resistance was only 2 to 8%. Also, under a pressure of 1000Kg, 50kA (rm
s.) was applied for 3 seconds, there was no problem in tripping, and the increase in contact resistance after that was only 0 to 5%, indicating sufficient welding resistance. It should be noted that similar effects were obtained when the contact portion 3b was made of a composite metal having a component composition or a composite metal having a component composition. (4) Breaking ability of small delayed current (inductive load) The current cutting value when 30A is applied is the average
3.9A (standard deviation σn=0.96, number of samples n=100). In addition, when the contact part 3b is made of a composite metal with a component composition, the average resistance is 3.7A (σn=1.26, n=100),
When using a composite metal with a component composition, an average of 3.9A
(σn=1.5, n=100). (5) Breaking ability of small leading current (capacitive load) Voltage: 84kV×1.25/√3, 80A small leading current test (JEC-181) was conducted 10,000 times, but no restrike occurred. It was hot. In addition, similar results were obtained when the contact portion 3b was made of a composite metal having a component composition or a composite metal having a component composition. By the way, the component composition of the composite metal forming the contact portion 3b is Cu20-70% by weight, Cr5-70% by weight,
When the composition was outside the Mo5 to 70% by weight range, satisfactory properties could not be obtained. That is, if Cu is less than 20% by weight,
The inductivity decreased and the contact resistance increased significantly, while when it exceeded 70% by weight, the welding force and shear value increased significantly and the dielectric strength decreased significantly. Furthermore, when Cr content is less than 5% by weight, the dielectric strength decreases significantly;
When it exceeded 20%, the dielectric constant and mechanical strength were significantly reduced. Further, when Mo was less than 5% by weight, the dielectric strength was significantly lowered, while when it was more than 70% by weight, the mechanical strength was significantly lowered and the cleavage value became significantly larger. In addition, in the above-mentioned embodiment, a case was described in which the coil 4 is a 1/2 shunt type, but the coil 4 is not limited to this. For example, the coil 4 is of a 1 turn, a 1/3 shunt type, or a 1/4 It is also good as a branch type. Further, 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. may be connected directly to the center of the back of the electrode. Furthermore, the coil 4 is not limited to the case where the coil 4 is provided on the back of the electrode 3;
Of course, the coil may be arranged so as to surround the pair of electrodes, or the coil may be arranged outside the vacuum vessel as described in Japanese Patent Publication No. 13045/1983. Effects of the Invention As described above, the present invention forms the arc diffusion part of each electrode of a vacuum interrupter with austenitic stainless steel, and the contact part with Cu20~
70wt%, Cr5~70wt% and Mo5~70wt%
Since it is made of a composite metal consisting of, the current interrupting ability can be greatly improved compared to conventional ones. Furthermore, it is possible to obtain excellent dielectric strength similar to the conventional one in which the contact portion is formed of a 20Cu-80W alloy.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing one embodiment of the vacuum interrupter of the present invention, FIGS. 2 and 3 are longitudinal sectional views and exploded perspective views of the electrodes in FIG. 1, respectively, and FIGS. 4A, B, and C. , D, Figure 5 A, B, C,
D and FIGS. 6A, B, C, and D are X-ray photographs showing the structural states of different compositions of the composite metal forming the contact portion, respectively. 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 that applies an axial magnetic field parallel to the arc inside a vacuum vessel, the arc diffusion portion of each electrode is formed of austenitic stainless steel, and the contact portion is made of copper 200. A vacuum interrupter characterized in that it is formed of a composite metal consisting of ~70% by weight, 5-70% by weight of chromium, and 5-70% by weight of molybdenum.