JPH0719512B2 - Vacuum interrupter - Google Patents

Description

The present invention relates to a vacuum interrupter, and more particularly to a vacuum interrupter having means for applying an axial magnetic field parallel to an arc.

B. Outline of the Invention The present invention is a vacuum interrupter having means for applying a magnetic field in the axial direction to an arc, which is provided with an electrode having a cap-shaped disc formed of a contact portion and an arc diffusing portion, and facing surfaces of the electrodes. Is formed of a thin plate made of a material with a low flashover probability, and parts other than the facing surface are made of a material with a low conductivity, the re-ignition probability is extremely low, and high voltage, large current resistance and disconnection capability are achieved. It is excellent in that it can be opened and closed many times.

C. Conventional technology In recent years, by applying an axial magnetic field parallel to the arc, the arc is dispersed on the electrode surface to prevent local concentration of the arc, thereby preventing excessive melting of the electrode. There is known a vacuum interrupter of so-called longitudinal magnetic field application system, which is designed to improve the breaking performance and the breaking performance.

Conventionally, such a vacuum interrupter is disclosed in, for example, Japanese Patent Laid-Open No. 60-50.
It is disclosed in Japanese Patent Publication No. 828 and Japanese Patent Laid-Open No. 60-74316,
As shown in FIG. 2, a pair of electrode rods 2, 2 are introduced relatively close to and away from each other by positioning them in the vacuum vessel 1 on the axis thereof, and each electrode rod 2 has a cap-shaped circle at the inner end thereof. Plate-shaped pair of electrodes
3 and 3 are fixed by interposing an insulating spacer, and each electrode rod 2
And the electrode 3 are arranged at the back of the electrode 3 and the current in the axial direction (vertical direction in FIG. 2) flowing through the electrode rod 2 is changed to a loop current centered on the electrode rod 2 to generate a longitudinal magnetic field. The coils 4 and 4 which are magnetic field generating members are connected to each other to be generally configured.

That is, the vacuum container 1 is made of Fe-N in which one cylindrical insulating cylinder 5 made of glass or ceramics is fixed at both ends.
The thin-walled annular sealing metal fittings 6, 6, ... Made of i-Co alloy, Fe-Ni alloy, etc. are joined together to form one insulating cylinder, and both open ends are sealed with the other. The metal end plates 7, 7 are closed via the metal fittings 6, 6 and the inside is evacuated to a high vacuum (for example, a pressure of 6.665 mpa or less). Then, in the vacuum container 1, each of the electrode rods 2 is
Are introduced from the center of each metal end plate 7 so as to be relatively close to and away from each other while maintaining the airtightness of the vacuum container 1.

One electrode rod 2 (upper side in FIG. 2) is hermetically attached to one metal end plate 7, and the other electrode rod 2 is attached to the vacuum container 1 via a metal bellows 8. The other metal end plate 7 is inserted movably in the axial direction while maintaining airtightness. In FIG. 2, 9 and 10 are shaft shields and bellows shields, 11 is a main shield, and 12 is an auxiliary shield.

As shown in FIGS. 3 and 4, the inner end portion of each electrode rod 2 is made of a material having high conductivity such as Cu, and
Disc-shaped mounting base 4a with a diameter appropriately larger than the diameter of the electrode rod 2
And two arms 4b extending outward in the radial direction (horizontal direction in FIG. 3) from opposite positions on the outer circumference of the mounting base 4a, and the same direction from the end of each arm 4b about the mounting base 4a. A 1/2 branch type coil 4 consisting of a circular arc-shaped curved portion 4c is fixed by brazing via a recess 13 formed on one surface (downward in FIG. 3) of the mounting base 4a. .

The coil 4 includes a ring-shaped mounting portion 14a fitted to the outer periphery of the inner end of the electrode rod 2 by brazing, and a plurality of support arms 14b radially extending outward from the outer periphery of the mounting portion 14a.
And a ring-shaped support portion 14c that connects the ends of the support arms 14b.
And the coil reinforcement 14 made of and are brazed and reinforced with.

The coil reinforcement 14 is made of a material having 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 such as stainless steel or Inconel having high mechanical strength and low conductivity. The insulating spacer 16 formed in a cylindrical shape,
It is fixed by brazing via a small diameter flange 16a formed at one end thereof. Then, the large-diameter flange 16b formed on the other end of the insulating spacer 16 is mounted in the shape of a circular plate having a through hole having a diameter substantially larger than that of the large-diameter flange 16b and having a diameter substantially equal to the inner diameter of the insulating spacer 16. Base 17a and mounting base 1
Two arms 17b extending from the opposite positions on the outer circumference of 7a to the outside of the radial direction, and coil 4 from the end of each arm 17b.
The circular arc portion 17c has a radius of curvature substantially equal to that of the circular arc portion 4c and is curved in an arc shape with an appropriate length in the opposite direction.
The auxiliary coil 17 made of a material having high conductivity such as copper is fixed by brazing via an engaging step portion 18 provided on one surface (downward in FIG. 3) of the mounting base 17a. ing. And the auxiliary coil 17 and the coil 4 are
Axial energization with one end fixed to a recess 19 provided at the end of each arc portion 17c of the auxiliary coil 17 and the other end inserted into a through hole 21 provided at the end of each arc portion 4c of the coil 4. It is electrically connected via pin 20.

On the auxiliary coil 17, the electrode 3 formed to have a diameter substantially the same as the diameter of the coil 4 is joined to the mounting base 17a by brazing via a recess 22 provided in the center of the back surface, and is brazed via the back surface. It is joined to each arm 17b and the arc portion 17c. The electrode 3 is a facing surface (upper surface in FIG. 3).
An arc diffusing portion 3a is provided which has a circular recess 23 in the center and is gradually thinned toward the periphery to form a shaded disk shape.
And a contact portion 3b which has a flat circular contact surface on the opposite surface and is formed in a shaded disk shape which gradually becomes thinner toward the periphery and which is fixed to the recess 23 of the arc diffusion portion 3a by brazing. , Is provided as a cap-shaped disc as a whole.

The arc diffusion portion 3a of the electrode 3 comprises 30 to 70% by weight of C and austenitic stainless steel (for example, SuS304,316L).
u30 to 70% by weight, or Cu20 to 70% by weight, chromium Cr5 to 40% by weight, and iron Fe 5 to 40% by weight. Further, the contact portion 3b is
Cu20-70wt%, Cr5-70wt% and molybdenum Mo5-7
It is made of a composite metal of 0% by weight.

D. Problems to be Solved by the Invention The above-described conventional vacuum interrupter has excellent breaking and breaking performance, is particularly excellent in breaking and breaking a large current due to an accident, and exhibits high withstand voltage characteristics.

However, when this vacuum interrupter was used for opening and closing a capacitor, reignition was observed. Unlike the normal load switching, when the capacitor is opened and closed, twice the voltage of the system voltage is applied between the electrodes when the contact is opened, and when it is turned on, an instantaneous large current (rush current) of about 5 times the system current is applied.
Flows. When switching capacitors, the voltage and current values are smaller (greater than load switching) when compared to the case of a circuit failure or disconnection at the time of a system fault, but the capacitor circuit is destroyed unless it is reliably switched more than 10,000 times. There is a risk of causing it.

E. Means for Solving the Problems In order to solve the above-mentioned conventional problems, the present invention introduces a pair of lead rods into a vacuum container so that the lead rods can be relatively moved toward and away from each other. Each electrode of a vacuum interrupter, in which a cap-shaped disc-shaped electrode including a contact portion and an arc diffusion portion is fixed to an end portion, and a magnetic field generating member for applying an axial magnetic field parallel to the electrode is applied to the arc. The opposing surface of is formed of a thin plate made of a composite metal having a conductivity of 40 to 70% with a copper content of 20 to 80% by weight, chromium of 5 to 70% by weight, and molybdenum of 5 to 70% by weight. Was formed of a material having a conductivity of less than 40%.

In addition, the diameter of the back surface of the contact part was made larger than the diameter of the contact part surface of the thin plate, and the surface and the back surface of the arc diffusion part of the thin plate were made parallel to each other, and the tilt angles formed by the surface and the back surface with the contact part plane were made equal . As a result, the thickness of the thin plate in the arc diffusion portion is thinner and more uniform than the thickness of the thin plate in the contact portion.

In the present invention, the material of the thin plate forming the facing surface of the electrode is
When the Cu content was less than 20% by weight, the conductivity was lowered and the contact resistance was remarkably increased. When the Cu content was more than 80% by weight, the welding force and the breaking value were remarkably increased and the dielectric strength was remarkably lowered. When Cr is less than 5% by weight, the dielectric strength is remarkably lowered, and when it exceeds 70% by weight, the electrical conductivity and the mechanical strength are remarkably lowered. Further, when Mo is less than 5% by weight, the dielectric strength is remarkably reduced, and when it is more than 70% by weight, the mechanical strength is remarkably lowered, and further, the breaking value is remarkably increased. When the conductivity (IACS%) of the material of the thin plate that forms the electrode facing surface is less than 40%, the contact resistance increases, and when it exceeds 70%, eddy current occurs and the magnetic flux density remarkably increases. Fell.

Further, the thickness of the contact portion of the thin plate is preferably 4 to 2 mm, and when it exceeds 4 mm, the eddy current increases remarkably and the cutting performance is deteriorated. When it is less than 2 mm, the erosion due to frequent opening and closing is caused. I can not cope. Further, the thickness of the arc diffusion portion of the thin plate is preferably 2 mm or less, and if it exceeds 2 mm, the eddy current increases and the cutting performance deteriorates.

On the other hand, if the material of the part other than the facing surface of the electrode has a conductivity of more than 40%, an eddy current is generated and the effect due to the longitudinal magnetic field is attenuated, and a large current cannot be cut off. . Considering the prevention of eddy current and the capacity of energizing current, it is desirable that the conductivity is 4 to 10%, the plate thickness under the arc diffusion part is 5 mm or less, and the plate thickness under the contact part is good. It is better to be as thin as possible. The conductivity is 40
% Or less, for example, stainless steel, Cu30-70
Wt% and stainless steel 30-70 wt% composite metal or Cu 20-70 wt%, Cr5-40 wt% and Fe5-40
There are composite metals and the like made up of wt%.

In addition, when the angle formed by the contact portion surface and the arc diffusion portion surface of the thin plate is 2 to 10 °, excellent shearing performance is shown,
Particularly, it is most preferable that the angle is 3 to 5 °.

F. Action According to the vacuum interrupter with the above configuration, even when it is used for opening and closing a capacitor, there is little decrease in withstand voltage due to the rush current at the time of turning on, frequent opening and closing is possible, and a large current is turned on and off. You can

G. Example Hereinafter, the present invention will be described in detail based on an example shown in FIG. In FIG. 1, the same parts as those in the conventional art are shown with the same reference numerals as those in FIG. 4, and the description thereof will be omitted.

FIG. 1 shows an electrode in one embodiment of the present invention.
The diameter of the auxiliary coil 17 is approximately the same as the diameter of the coil 4 (outer diameter 80
mm-shaped disk-shaped electrode 30 is joined to the base 17a by brazing through a recess 31 provided in the center of the back surface thereof, and each arm 17b is brazed through the back surface.
And is joined to the arc portion 17c. The opposing surface of the electrode 30 is formed of a cap-shaped thin plate 32 made of a composite metal having 60% by weight of Cu, 30% by weight of Mo and 10% by weight of Cr and having an electric conductivity (IACS%) of 50 to 60%. That is, the central portion of the thin plate 32 is provided with a contact portion 33 which is disc-shaped and has an outer diameter of 30 mm and which can be contacted with and separated from the counter surface electrode.
The arc diffusion portion 34 is an inclined surface provided at an angle of 5 ° with the surface of the contact portion 33.

In addition, from the diameter D _{1 of the} surface of the contact portion 33 of the thin plate 32, the contact portion
The diameter D ₂ of the back surface 33 is formed larger, and the back surface of the arc diffusion portion 34 in the thin plate 32 is formed parallel to each other. Therefore, the plate thickness t ₂ of the thin plate 32 in the arc diffusion portion 34 is smaller than the plate thickness t ₁ of the thin plate 32 in the contact portion 33 and is formed uniformly.

In this embodiment, the plate thickness t ₁ of the thin plate 32 at the contact portion 33 is
The plate thickness t ₂ of the thin plate 32 in the arc diffusion portion 34 is 2.5 mm and ₂ mm, respectively. Further, the diameter D ₃ of the large-diameter flange 16b of the insulating spacer 16 and the diameter D _{1 of the} surface of the contact portion 33 of the thin plate 32 are formed so that D ₁ ≦ D ₃ . D ₁
≦ D ₃ is for mechanical reinforcement, and it is the large-diameter flange 16b that exerts a force on 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 (IACS%) of 7% of 40Cu-20Cr-40.
It is made of Fe. The thin plate 32 and the back surface part 35 are brazed together, or the components except for Cu are used for the thin plate 32 and the back surface part.
A skeleton forming 35 and 35 is made, both are overlaid, and Cu is infiltrated at once to manufacture.

The electrode having the above structure was applied to the vacuum interrupter shown in FIG. 2, the vacuum interrupter was incorporated into a circuit for opening and closing a capacitor, and the flashover probability was investigated. The results are shown in the table below.

The test method was made equivalent to the switching condition of the capacitor capacity of 66kV-60MVA. Regarding the charging conditions, a capacitor was charged with a direct current voltage of 54 kVr.ms in advance, and a current of 3700 A peak, 200 cycles was applied by LC vibration. On the other hand, the disconnection is a 50-cycle power supply voltage of 50 kVr.ms, and a leading current of 520 A,
The charging and disconnection were repeated many times under these conditions. The gap between poles is 15 mm, the closing speed is 1 m / sec, and the breaking speed is
It is 2m / sec.

In addition, high current and breaking ability are also shown in the following table. The rated condition is 72kV (re-starting voltage 123kV),
For comparison, a vacuum interrupter (conventional example 1) having a conventional electrode shown in FIG. 3 and the electrode structure shown in FIG. All parts 35 and 60 are 60Cu-30Mo-10
With respect to a vacuum interrupter (conventional example 2) having an electrode formed of a Cr composite metal, the flashover probability and the large current breaking / breaking ability were examined under the same test conditions as those of the above-mentioned examples, and the results are shown in the following table. Shown inside.

As can be seen from the above table, according to the example, the conventional example 1
The flashover probability was significantly lower than that of No. 1 and the occurrence of re-strikes was almost eliminated. That is, the vacuum interrupter of the embodiment is optimal for opening and closing a capacitor.

Further, the vacuum interrupter of the example showed the same breaking performance as the vacuum interrupter having the electrode structure of Conventional Example 1.

H. Effect of the Invention As described above, according to the vacuum interrupter of the present invention, the facing surface of the electrode of the cap-shaped disk is formed of a thin plate made of a material having a low flashover probability, and the portion other than the facing surface has low conductivity. The thickness of the thin plate in the arc diffusion part is thinner than the thickness of the thin plate in the contact part and is formed uniformly, so the probability of re-ignition is extremely high. It is low in temperature, can be opened and closed frequently, and is most suitable for opening and closing a capacitor. It also has excellent characteristics such as high voltage, high current and disconnection ability as a normal vacuum interrupter.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view of an electrode in one embodiment of the vacuum interrupter of the present invention, FIG. 2 is a vertical sectional front view of a conventional vacuum interrupter, and FIG. 3 is a vertical sectional front view of an electrode in FIG. FIG. 4 is an exploded perspective view of the electrode shown in FIG. 1 ... Vacuum container, 2 ... Electrode rod, 4 ... Coil (magnetic field generating member), 30 ... Electrode, 32 ... Thin plate, 33 ... Contact part, 34
...... Arc diffuser, 35 ...... Back surface (portion other than facing surface), D1 ...... Contact surface diameter, D2 ...... Contact surface back diameter, t1 ...... Thin plate thickness at contact area, t2 ... ... Thickness of the thin plate in the arc diffusion part.

Claims (1)

[Claims] 1. A pair of lead rods are introduced into a vacuum container so as to be relatively close to and away from each other, and a cap-shaped disc-shaped electrode having a contact portion and an arc diffusion portion is fixed to the inner end portion of each lead rod. Then, in the vacuum interrupter comprising a magnetic field generating member for applying an axial magnetic field parallel to the arc, a facing surface of each of the electrodes has a copper content of 20 to 80% by weight, a chromium content of 5 to 70% by weight, and a molybdenum content of 5%. ~ 70% by weight, conductivity 40 ~ 70%
In addition to forming a thin plate made of a composite metal, the parts other than the facing surface of the electrode are made of a material having a conductivity of less than 40%, and the diameter of the back surface of the contact part is made larger than the diameter of the contact part surface of the thin plate. A vacuum interrupter characterized in that the front surface and the back surface of the arc diffusion portion are parallel to each other, and the thickness of the thin plate in the arc diffusion portion is thinner than the thickness of the thin plate in the contact portion and is uniform.