JPS63236228A - Vacuum interruptor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vacuum interrupter, and is particularly useful when applied to a vacuum interrupter equipped with means for applying an axial magnetic field parallel to an arc. It is.

B. Summary of the Invention The present invention provides a vacuum interrupter provided with a cap-shaped disk-shaped electrode consisting of a contact part and an arc diffusion part, and provided with means for applying an axial magnetic field to the arc, The facing surface of the electrode is formed of a thin plate made of a composite metal with high conductivity, and the parts other than the facing surface of the electrode are formed of a material with low conductivity. is made larger and the front and back surfaces of the arc diffusion part of the thin plate are made parallel, and the thickness of the thin plate in the arc diffusion part is equal to the thickness of the thin plate in the contact part.
Moreover, by forming it uniformly and by making the boundary between the back surface of the contact part and the back surface of the arc diffusion part a curved chamfer, the probability of restriking is extremely low, and the ability to interrupt high voltages and large currents is improved. The vacuum incluctor can be opened and closed frequently by providing an electrode with excellent mechanical durability.

C Conventional technology As a type of vacuum interrupter, by applying an axial magnetic field parallel to the arc, the arc is dispersed over the electrode surface, thereby preventing its local concentration and thereby preventing excessive melting of the electrode. A so-called vertical magnetic field application type vacuum interrupter is known, which aims to improve interrupting performance by preventing

This type of vacuum interrupter according to the prior art has a vacuum capacity V!, as shown in FIG. A pair of lead rods 2゜2 are positioned on the axis of the IJl and introduced so as to be able to move toward and away from each other, and a pair of electrodes 3 in the shape of a cap-shaped disk are installed at the inner end of each IJ lead rod 2. .3 is fixed with an insulating spacer interposed,
It is roughly constructed by connecting each lead rod 2 and electrode 3 with coils 4, 4, which are magnetic field generating members that generate a vertical magnetic field.

To further comment, the vacuum container 1 is a thin annular seal 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. It is joined through one of the fittings 6, 6... to form a single insulating cylinder, and its both open ends are connected to disk-shaped metal end plates 7, 7 through the other sealing fittings 6, 6. closed and the inside is placed under high vacuum (e.g. 6.665 m
It is formed by evacuating to a pressure of less than Pa). and,
Each of the lead rods 2 is 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 the vacuum container 1 while maintaining airtightness.

One (upper in FIG. 4) lead rod 2 is hermetically inserted into one metal end plate 7, and the other lead rod 2 is connected to the vacuum vessel 1 through a metal bellows 8. is held and pushed through the other metal end plate 7 so as to be freely movable in the axial direction. Further, in FIG. 4, 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 lead rod 2, as shown in FIGS. 5 and 6, there is a disk-shaped disc made of a material with high conductivity such as Cu and having a diameter suitably larger than the diameter of the lead rod 2. A mounting base 4a, two arms 4b extending outward in the radial direction (in the left-right direction in FIG. 5) from opposing positions on the outer periphery of the mounting base 4a, and two arms 4b extending outward from the ends of each arm 4b to the mounting base 4.
A rod-shunting type coil 4 consisting of an arcuate portion 4c curved in an arc shape in the same direction with a as its center is brazed through a recess 13 formed on one (lower side in Fig. 5) surface of the mounting base 4a. It is fixed.

The coil 4 has a ring-shaped attachment part 14a fitted to the outer periphery of the inner end of the lead rod 2 by brazing, and an attachment part 14a.
Extending radially outward from the outer periphery of ? : It is reinforced by being brazed to the coil reinforcing body 14, which is made up of a plurality of support arms 14b and a ring-shaped support part 14c that connects the ends of each support arm 14b.

The coil reinforcing body 14 is made of a material having mechanical strength holes and low electrical conductivity, such as stainless steel.

A circular recess 15 is provided on the other side of the mounting base 4a of the coil 4, and the recess 15 is made of a mechanically strong hole and a low conductivity material such as stainless steel or Inconel. An insulating spacer 16 formed in a cylindrical shape is fixed by brazing via a small diameter 7 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. Base 17a and mounting base 17a
two arms 17b extending radially outward from opposing positions on the outer periphery of the coil 4;
A circular arc portion 1 having a radius of curvature approximately equal to that of the circular arc portion 4C and curved in an arc shape with an appropriate length in the same direction opposite to the circular arc portion 4C.
7c, and is made of a highly conductive material such as copper.
It is fixed by brazing via an engagement step 18 provided on the surface (lower in the figure). The auxiliary coil 17 and the coil 4 have one end fixed to a recess 19 provided at the end of each arcuate portion 17c of the auxiliary coil 17, and the other end provided at the end of each arcuate portion 4C of the coil 4. They are electrically connected via an axial current-carrying pin zO inserted into the through hole 21.

In the auxiliary coil 17, the amount tIi 3 formed to have approximately the same diameter as the coil 4 is connected to the recess 2 provided at the center of the back surface.
2 to the mounting base 17a by brazing, and also to each arm 17b and the arc portion 17c by brazing through the back surface. The electrode 3 has a circular recess 23 in the center of the opposing surface (upper surface in FIG. 5) and an arc diffusion section 3a formed in the shape of a hat-shaped disk that gradually becomes thinner as it approaches the periphery, and a flat circular recess 23 on the opposing surface. The concave portion 23 of the arc diffusion portion 3a is formed in the shape of a cap-shaped disk and has a contact surface of
The contact portion 3b is fixed to the contact portion 3b by brazing, and the entire contact portion 3b is provided in the shape of a cap-shaped disk.

The arc diffusion part 3a of the Wk pole 3 is made of austenitic stainless steel (for example, SuS 304°316L, etc.) 3
0-70% by weight and Cu30-701! Amount % to Naro composite metal, 3 to 70% by weight Cu2O, chromium Cr
It is made of a composite metal consisting of 5 to 40% by weight of iron Fs and 5 to 40% by weight of iron Fs. Further, the contact portion 3b is C
u 20~70 fflft%, Cr5~? O3i %
and molybdenum Mo in an amount of 5 to 70% by weight.

FIG. 7 is a vertical cross-sectional view showing an extracted electrode 3 and its vicinity according to a conventional technique in which the structure of the electrode 3 is different. As shown in the figure, this electrode 3 is connected to the arc diffusion section 3 shown in FIG.
The entire surface is made of a uniform material in the shape of a combination of the contact portion 3b and the contact portion 3b. This uniform material over the entire surface is made of a material having the same composition as the contact portion 3b shown in FIG.

Note that in FIG. 7, the same parts as in FIG. 5 are given the same numbers and redundant explanations will be omitted.

D. Problems to be Solved by the Invention The above-mentioned conventional vacuum incrector has excellent interrupting performance, particularly excellent in interrupting large currents in the event of an accident, and exhibits high withstand voltage characteristics.

However, when this vacuum interrupter was not used for opening and closing the capacitor, restriking occurred.

That is, in the case of the electrode 3 shown in FIG. 5, the arc tends to concentrate on the stepped part of the boundary between the arc diffusion part 3a and the contact part 3b due to its shape, and the surface of the electrode 3 becomes rough when the capacitor circuit is opened and closed. Therefore, there is a problem that the withstand voltage characteristics deteriorate.

On the other hand, in the case of the electrode 11i3 shown in FIG. 7, since there is no stepped portion in shape, the problem as in the case of the above-mentioned ri pole shown in FIG. 5 is unlikely to occur. However, if the material of electrode 3 is C
Since the conductivity of u-Cr-Mo is high, there is a problem that the magnetic flux generated by the coil 4 is canceled due to the influence of eddy current, the magnetic flux density decreases, and the interrupting performance deteriorates.

Incidentally, when switching a capacitor, unlike normal load switching, a voltage twice the grid voltage is applied between the poles when the capacitor is opened, and an instantaneous large current (rush current) about five times the grid current flows when the capacitor is turned on. . When switching a capacitor, the voltage,
Each value of the current is small compared to the circuit cutoff at the time of a system fault (larger than the load switching), but if the capacitor circuit is not switched reliably by more than -Gallo, there is a risk that the capacitor circuit will be destroyed.

E Means for Solving the Problems The structure of the present invention for solving the above-mentioned conventional problems is that in a vertical boron vacuum incluctor, a cap-shaped disk-shaped ff
The facing surface of the i-pole is made of a thin plate made of copper, chromium, and molybdenum that is uniform over the entire surface, and the back surface of this thin plate is made of a high-resistance material. The electrode is characterized by having a curved chamfered portion at the boundary with the back surface of the arc diffusion portion, which is the peripheral portion of the arc diffusion portion.

F Effect According to the present invention having the above configuration, the thin plate that is the opposing surface of the electrode is mechanically reinforced at the back surface. In particular, since the boundary between the back surface of the contact part, which is a flat part of the thin plate, and the back face of the arc diffusion part, which is the peripheral part of the thin plate contact part, is made into a curved surface, the machine when the vacuum interrupter is turned on acts on this part. target stress is dispersed. Further, since the thin plate is made of a uniform material of high conductivity, the arc generated when the vacuum interrupter is opened and closed is well dispersed on the surface of the thin plate. Further, since the portion made of a high conductivity material is a thin plate and the back portion is made of a high resistance material, the eddy current in the electrode portion is small.

G. Example Hereinafter, the present invention will be explained in detail based on an example shown in FIG. In FIG. 1, parts that are the same as those in the prior art are designated by the same reference numerals as in FIGS. 5 and 7, and redundant explanation will be omitted.

FIG. 1 shows an electrode in an embodiment of the present invention.
In the auxiliary coil 17, an electric field 30 in the shape of a cap-shaped disk formed with approximately the same diameter as the diameter of the coil 4 (outer diameter 80 m) is joined to the mounting base 17a by brazing through a recess 31 provided at the center of the back surface. At the same time, it is joined to each arm 17b and arc portion 17c by brazing through the back surface.

The opposing surface of the electrode 30 is made of Cu 49% by weight, M.

38! ! electrical conductivity (IAC
3%) and 50 to 60% composite metal, the thin plate 32 is made of a hat-shaped disk-shaped material that is uniform over the entire surface. That is, a contact part 33 is provided in the center of the thin plate 32 in the shape of a disc with an outer diameter of 30 m and can freely come into contact with and separate from the counter electrode.
The portion having a diameter larger than 3 is an arc diffusion portion 34 having an inclined surface formed at an angle of about 5 degrees with the surface of the contact portion 33.

Further, the diameter D2 of the back surface of the contact portion 33 is larger than the diameter D1 of the front surface of the contact portion 33 in the thin plate 32, and the front and back surfaces of the arc diffusion portion 34 in the thin plate 32 are formed in parallel. Therefore, the thickness t2 of the thin plate 32 in the arc diffusion part 34 is thinner and uniform than the thickness t1 of the thin plate 32 in the contact part 33.

In this embodiment, the thickness t of the thin plate 32 in the contact portion 33 is approximately 2.5 m+a, and the thickness t2 of the thin plate 32 in the arc diffusion portion 34 is approximately 2 m.

Generally, the thickness of the contact portion 33 of the thin plate 32 is 4 to 2 m.
m is preferable; if it exceeds 4III11, the increase in the thin current will be significant and the breaking performance will deteriorate;
! If it is less than 1, it will not be possible to cope with erosion due to frequent opening and closing. Further, the arc diffusion portion 34 in the thin plate 32
The plate thickness is preferably 2IIll or less; if it exceeds 2IIll, eddy current will increase and the breaking performance will deteriorate.

Furthermore, the diameter D of the large diameter flange 16b of the insulating spacer 16
3 and the diameter of the surface of the contact portion 33 of the thin plate 32 are formed so that D, ≦D3. D1≦D3
This is for mechanical reinforcement, and it is the large diameter flange 16b that applies force to the contact portion 33.

On the other hand, the back surface portion 35, which is a portion other than the facing surface of the electrode 30 (other than the thin plate 32), has a conductivity of 40% (IAC 3%) of 7%.
It is made of Cu-20Cr-40Fe. The thin plate 32 and the back part 35 are connected to the fistula or Cu.
A skeleton forming the thin plate 32 and the back surface part 35 is made from the components except for , the two are overlapped, and Cu is infiltrated all at once. That is, the back surface portion 35 is bonded to the back surface of the thin plate 32.

At this time, if the back surface portion 35 has a conductivity exceeding 40%, eddy currents will be generated and the effect of the vertical magnetic field will be attenuated, making it impossible to cut off the large current. Considering prevention of eddy current and current carrying capacity, the conductivity is preferably 4 to 10%, and the plate thickness below the arc diffusion is 5%.
A value of fl or less shows good results, and it is better that the thickness of the plate below the contact area be as thin as possible.

Examples of materials with electrical conductivity of 40% or less include stainless steel, Cu30-70ifi%, and stainless steel 5.
Composite metal consisting of v430-70% or Cu2
0-70% by weight, 5-40% by weight of Cr and 5-4% by weight of Fe
There are composite metals starting from 0% by weight.

Further, when the angle between the surface of the contact portion and the surface of the arc diffusion portion in the thin plate 32 is between 2 and 10 degrees, excellent breaking performance is exhibited, and particularly when the angle is between 3 and 5 degrees, the best performance is achieved.

Furthermore, the boundary between the back surface of the contact part 33, which is a flat part of the thin plate 32, and the back surface of the arc diffusion part 34, which is an inclined part of the thin plate 32, is shown in FIG. 2 by extracting and enlarging part A in FIG. As shown, the chamfered portion R is a curved surface. In other words, the plane portion 36 that is a portion of the back surface portion 35 that is parallel to the contact portion 33
Similarly, the boundary portion of the back surface portion 35 with the inclined portion 37, which is a portion parallel to the arc diffusion portion 34, is a chamfered portion similar to the chamfered portion R described above.

The electrode with the above configuration was applied to the vacuum interrupter shown in FIG. 4, and the vacuum interrupter was incorporated into a circuit for opening and closing a capacitor, and the flash fault probability was investigated. The results are shown in the table below.

The test method was made to be equivalent to the opening/closing conditions of a 66 kV-60 MVA (7): I-in-sa container.

The input conditions are that a DC voltage of 54k Vr is applied to the capacitor in advance.
* Charge m6 S11 and use LC vibration to 370
A current of 0 A peak and 200 cycles was applied.

On the other hand, the 50-cycle power supply voltage 501 (Vr,
The rn6 so p current was set to a leading phase current of 520 A, and the switching on and off was repeated many times under this condition.

In addition, the gap between poles is 15m, and the input speed is im/s.
ee, Lt4p breaking speed is 2 m/sea.

In addition, the large current breaking strength is also listed in the table below. The new conditions are rated voltage 72kV (restart voltage 123kV)
kV), t/+ breaking velocity was 3.5 rn/s.

For comparison, the vacuum interrupter with conventional electrodes shown in FIG. 5 (Conventional Example 1) and the vacuum interrupter with conventional electrodes (Conventional Example 2) shown in FIG. The flash fault probability and large current breaking power were investigated under the same test conditions as those of the previous model, and the results are shown in the table below.

As can be seen from the table above, the example according to the example is the conventional example 1.
In addition, the flashover probability is significantly lower than that of the conventional vacuum incluctor, and the occurrence of restrike is almost eliminated.In other words, the vacuum incluctor of this embodiment is most suitable for opening and closing capacitors.

Further, the vacuum interrupter of the example exhibited the same interrupting performance as the vacuum interrupter of the conventional example 1 having the electrode structure.

Furthermore, when a vacuum interrupter having the electrode 30 was subjected to an opening/closing durability test of 10,000 times, no mechanical damage was observed in the electrode 30.

The input speed at this time was 1.3 m/see, l,
The breaking speed was 3.5 m/see.

On the other hand, in the electrode 40 shown in FIG. 3, a crack C occurred in the thin plate 42 after 3,000 cycles of the opening/closing durability test under the same conditions. FIG. 3 is an enlarged view extracting and showing a portion corresponding to portion A in FIG. 1, that is, an enlarged view corresponding to FIG. 2. As shown in the figure, this electrode 40 does not have a chamfered portion at the boundary between the back surface of the contact portion 43 and the back surface of the arc diffusion portion 44, and the cross-sectional shape is such that the two back surfaces intersect linearly. It is.

In the durability test, a crack C was generated from this intersection point toward the surface of the thin plate 42.

This is because the stress caused by the impact at the time of injection is concentrated at the boundary portion. In the electrode 30 of this embodiment, the chamfered portion R is provided at the boundary portion, so that the stress caused by the impact at the time of insertion is dispersed, and as a result, it has sufficient opening and closing durability.

In addition, in FIG. 3, 45 is the back head, 46 is a flat part of the back part 45, and 47 is an inclined part of the back part 45.

I (Effects of the Invention As described above, according to the vacuum incluctor of the present invention, the facing surface of the electrode on the cap-shaped disk is formed of a thin plate made of a highly conductive uniform material over the entire surface, and the back surface other than the facing surface is Since it is made of a material with low conductivity and sufficient mechanical strength, the probability of restriking is extremely low and frequent switching is possible, making it ideal for switching capacitors. It also exhibits excellent characteristics in terms of high voltage and large current breaking ability.

Furthermore, since the boundary between the back surface of the contact part of the electrode and the back surface of the arc diffusion part of the thin plate is a curved chamfer, the mechanical stress when the vacuum incretor is turned on is dispersed, and sufficient opening/closing durability is achieved. Become what you have.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional front view of an electrode in an embodiment of the vacuum interceptor of the present invention, FIG. 2 is an enlarged view showing part A of FIG. 1, and FIG. An enlarged view showing the corresponding parts extracted, FIG. 4 is a vertical sectional front view of a conventional vacuum interrupter, FIG. 5 is a vertical sectional front view showing an example of the electrode in FIG. 4, and FIG. 6 is shown in FIG. 5. FIG. 7 is an exploded perspective view of the electrode, and a longitudinal sectional front view showing another example of the FA pole in FIG. ), 30 is an electrode, 32 is a thin plate, 33 is a contact part, 34 is an arc diffusion part, 35 is a back part (a part other than the facing surface), and R is a chamfered part. IH;hke b Electrode II bloom front view Figure 5

Claims (1)

[Claims] A pair of lead rods are introduced into a vacuum container so as to be able to approach and separate from each other, and a cap-shaped disk-shaped electrode consisting of a contact part and an arc diffusion part is provided at the inner end of each lead rod. In a vacuum interrupter comprising a magnetic field generating member that is firmly fixed and applies an axial magnetic field parallel to the arc, the opposing surfaces of each electrode are made of 20 to 80% by weight of copper and 5 to 5% by weight of chromium.
The electrode is made of a thin plate made of a composite metal containing 70% by weight and 5% to 70% molybdenum and has an electrical conductivity of 40% to 70%, and the parts other than the facing surface of the electrode are made of a material having an electrical conductivity of less than 40%, and The diameter of the back surface of the contact part in the thin plate is larger than the diameter of the front surface of the contact part, and the front and back surfaces of the arc diffusion part in the thin plate are made parallel, so that the thickness of the thin plate in the arc diffusion part is thinner than the thickness of the thin plate in the contact part, Moreover, the vacuum interrupter is characterized in that it is formed uniformly and that the boundary between the back surface of the contact part and the back surface of the arc diffusion part is a curved chamfer.