JPH02201831A - Magnetic driving type electrode for vacuum interrupter - Google Patents

Abstract

PURPOSE:To improve the breaking performance by setting the outer diameter of a contact surface to be less than the diameter of a lead rod and connecting the lead rod with the back surface of a contact part directly, and setting a component of current ways at the time of energization of the crossing direction to the contact part larger than a component parallel to it. CONSTITUTION:The forward end part of a lead rod 25 is engaged with a throughholes 22 from the back surface side of an arc part 21, a flange part 26 provided in the outer circumferential surface of the lead rod 25 is applied to the back surface of a reinforcement plate 24, and the forward end part of the lead rod 25 and the arc part 21 are brazed with each other. A contact part 27 is engaged in the throughhole 22 on the surface side of the arc part 21, this contact part 27 has a bottom, a bottom surface 27a is tightly applied to a forward end surface 24a of the lead rod 25, and the circumferential surface of the contact part 27 is connected with the arc part 21 and the contact part bottom surface 27a with the lead rod forward end surface 24a by brazing respectively, so the lead rod 25 is directly connected with the back surface of the contact part 27. At the time of energization, most of current ways between the lead rod 25 and the contact surface 27b are of crossing direction to the contact surface 27b, so arc spreads radially and is extinguished by force of self-diffusion of metal steam produced at the time of breaking.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetically driven electrode for a vacuum interrupter that interrupts an arc by magnetic rotational driving.

B. Summary of the Invention The present invention provides an electrode for a magnetically driven vacuum interrupter, in which the outer diameter of the contact surface is made equal to or less than the diameter of the lead rod, and
By connecting a lead rod directly to the back of the contact part, in the current path formed between the contact surface and the lead rod, the current component in the direction perpendicular to the contact surface is divided into the current component in the direction perpendicular to the contact surface. The arc is made larger than the conventional one, and the arc is moved from the contact part to the arc part by the self-diffusion force of the arc due to the metal vapor at the time of breaking, and the arc is rotated and moved in the arc part to break it.

C. Prior Art Generally, as shown in FIG. 9, a vacuum interrupter has a fixed lead rod 3 having a fixed electrode 2 and a movable lead rod 5 having a movable electrode 4 and movable up and down in a vacuum container 1. Interior and configuration. In the figure, 6 is a bellows that makes the movable lead rod 5 movable, and 7 is a shield that covers the inner periphery of the vacuum vessel l.

The electrodes 2 and 4 of such a vacuum interrupter are required to have severe electrical characteristics such as large current breaking characteristics, low breaking current value characteristics, and high withstand voltage value characteristics.

However, since these characteristics are contradictory, it is difficult to achieve all of them at the same time. Therefore, conventionally, electrode materials have been selected with emphasis on one of the characteristics, or a special electrode structure has been adopted, depending on the purpose of the vacuum interrupter.

Under these circumstances, magnetically driven electrodes are known as a representative example of improving current cutting performance with the same electrode diameter.

Examples of magnetically driven electrodes are shown in FIGS. 6 and 7. As shown in the figure, this electrode 8 has a contact portion 11 provided at the center of one side of an arc portion 10 having a plurality of spiral grooves 9, and a lead rod 12 connected to the other side of the arc portion 10. The structure is designed to increase the cutoff limit by driving the arc in the outer circumferential direction using magnetic driving force and preventing local heating of the electrode.

Since this electrode 8 is intended to rotate the arc, various attempts have been made to ensure that the generated arc does not stagnate and continues to move until it reaches the zero current point.

That is, after the arc 13 is generated at point (■) in FIG. 6, it moves over the arc pedal 10a at points (■) and (■).

■Move as shown. At this time, the arc 13 collects the arcs generated one after another and rotates to form an arc column 13'.

The driving force for the arc 13 is the magnetic force F caused by the U-shaped current path generated in the electrode portion due to the component of the current Ih generated in the radial direction of the electrode 8 in FIG.

Therefore, in the past, in order to generate a large magnetic force F, B: the inner diameter of the contact portion 11 is made larger than the diameter of the lead rod 12; b: a high-resistance material ( The arc pedal 10a is lengthened by providing a so-called blowout ring 14 made of stainless steel (SUS steel), and by extending the inner end of the spiral groove 9 below the contact portion 11 as shown by 9a in FIG. 6. In addition, for the rotational movement of the arc, +1 = The tip of the arc pedal 10a is lengthened as shown by 10b in Figure 6 to make it easier for the arc to move to the adjacent pedal. b: Surrounding arc Measures are taken to consider the gap between the shield and the shield.

D. The iI that the invention attempts to solve! ! The idea behind conventional electrodes that take the above-mentioned measures is that the generated arc 1
3 to quickly apply a magnetic driving force by a so-called U-shaped force. Therefore, the movement of the arc 13 is that the arc 13 generated at one point grows as described above, and the arcs generated one after another are collected to form a large arc column.
3/ as if rotating.

However, even though the arc rotates, there is a magnetic driving force acting on the arc toward the outer circumference of the electrode.
The rotational movement of the arc ends only on a part of the electrode surface, and the entire surface of the ft electrode is not effectively utilized.

Therefore, breaking performance commensurate with the electrode diameter cannot be obtained,
In addition, as mentioned above, ■ lengthening the spiral groove 9, ■
Lengthen the arc pedal 10, ■Blowout ring 1
Even if measures such as providing 4 are taken, there is a limit to the improvement in performance.In particular, the measures 1 and 2 cause another problem of reduced durability.

FIG. 8 shows the relationship between the electrode diameter and current cutoff performance in a conventional electrode. The figure also shows a vertical magnetic field application type electrode. As can be seen from the figure, in magnetically driven electrodes, when the gll diameter exceeds a certain size,
No improvement in cutting performance can be expected.

In addition, especially when the breaking current exceeds 50 kA, the arc energy becomes large, so the local concentration of the arc cannot be prevented by magnetic driving force alone, and the electrode diameter is 110 to 120 kA.
m or more, the breaking performance hardly improves.

Furthermore, in a vacuum interrupter with a rated voltage of about 12 kV, the distance from the external wiring (indicated by "1" in Figure 9) is about 250 to 350 m, and the electromagnetic force is about 20 m.
Gauss/ k A -rm (magnetic flux density/current・
arc length), magnetic driving force F is 10 g f / k A
, -mm, so especially when the arc is located near the outer periphery of the arc pedal 10a (1 it at the ■ mark shown in Fig. 6), it becomes difficult for the arc to move in the circumferential direction, and the breaking performance deteriorates. descend.

As mentioned above, there was a limit to the improvement of the breaking performance due to the outward magnetic driving force, so the inventors of the present invention returned to the starting point and decided to contact the arc generated by the self-diffusion force of the metal vapor generated during the breaking. I tried to see if it was possible to move it from the section to the arc section.

In other words, the electrodes were constructed so that the outward magnetic driving force was as small as possible.

Specifically, the outer diameter of the contact part is set to be less than or equal to the diameter of the lead rod, and the lead rod is connected directly to the back of the contact part, so that the current path between the lead rod and the surface of the contact part is perpendicular to the surface of the contact part. (indicated by in Figure 10) will be the majority,
Care has been taken to ensure that the component in the direction parallel to the surface of the contact portion (indicated by O in FIG. 10) is as small as possible.

When a vacuum interrupter was assembled using this electrode and its interrupting performance was tested, the current interrupting performance was 10~10.
A result of 30% improvement was obtained. Furthermore, when we disassembled the product after the test and observed the electrode surface, we found that there were no localized double digits, and traces of arcs were seen on almost the entire electrode surface. It was delicious). From this, it was found that the entire electrode surface was effectively utilized.

In addition, there was less dirt and debris on the inner wall of the vacuum interrupter shield. This shows that it is possible to prevent a drop in withstand voltage after shutoff, and as a result, an increase in the number of large current shutoffs can be expected.

Therefore, good results can be obtained by moving the arc from the contact part to the arc part by the naturally occurring self-diffusion force, instead of forcing the generated arc to be driven by an outward magnetic force as in the past. It turned out that it was impossible.

E Means for Solving the Problems Based on the above findings, the present invention provides a contact portion having a ring-shaped contact surface in the center of one surface of an arc portion having a plurality of spiral grooves, and a contact portion having a ring-shaped contact surface on the other surface. In a magnetically driven electrode for a vacuum interrupter having a lead rod connected to a central portion, the outer diameter of the contact surface is set to be equal to or less than the diameter of the lead rod, and the lead rod is directly connected to the back surface of the contact portion. ,
At least when current is applied, the current component in the current path formed between the contact surface and the lead rod is defined as Iv, the component in the direction perpendicular to the contact surface, and I)l, the component in the direction parallel to the contact surface. Then, I v > r h.

The contact portion may be made of a material containing chromium or copper as a main component, such as a composite metal of Cu-Cr-MO.

Further, the arc portion is made of a material mainly composed of a magnetic material and copper, and a composite metal of Fa Cr or magnetic stainless steel-Cu may be used.

F Function In the vacuum interrupter electrode described above, when the current is cut off, each generated arc moves from the contact part to the arc part by the self-diffusion force of the generated metal vapor without causing an arc base, and each arc moves from the contact part to the arc part. Since the entire arc rotates,
Cutoff is performed by effectively utilizing the electrode surface.

G Embodiment FIGS. 1 and 2 show a plane of a vacuum interrupter electrode according to an embodiment of the present invention and its cross section taken along the I-■ arrow.

The arc portion 21 of the electrode has a disk ring shape with a through hole 22 in the center, and a large number of spiral grooves 23 are formed from near the inner surface of the through hole 22 to the outer peripheral surface. Here, the spiral groove 23 extends from the front and back of the arc portion 21 to 11
However, this may be a non-penetrating groove provided on the front surface, back surface, or both surfaces of the arc portion 2J.

In the electrode according to this embodiment, a reinforcing plate 24 made of stainless steel, Inconel, etc. is provided on the back surface of the arc portion 2J.

A lead rod 25 is inserted into the through hole 22 from the back side of the arc portion 21.
A flange portion 26 protruding from the outer surface of the reinforcing rod 25 is in contact with the back surface of the reinforcing plate 24. The tip of the lead rod 25 and the arc portion 21 are connected by brazing.

On the other hand, a contact portion 27 is fitted into the C through hole 22 on the surface side of the arc portion 21. This contact portion 27 has a bottom, and the bottom surface 27a is the tip surface 2 of the lead rod 25.
5a, and the peripheral surface of the contact portion 27 and the arc portion 21 and the bottom surface 27a of the contact portion and the tip end surface 25a of the lead rod are connected by brazing. In other words, the lead rod 25 is attached to the back of the contact portion 27.
The structure is such that they are directly connected.

The outer diameter of the contact surface 27b is set to be equal to or smaller than the diameter d of the lead rod 23.

In the embodiments shown in FIGS. 1 and 2, D=d, but as shown in FIG. 3, it may be Dad.

By determining the dimensions of each part and configuring the connections as described above, the contact surface 27b (contact part 27
The resistance of the path leading to the contact surface 27b is reduced, and a large current path in the direction perpendicular to the contact surface 27b is secured.

In addition, in this embodiment, the inner end of the spiral groove 23 is
It may be formed in a groove extending to the contact portion 27 as shown by the two-dot chain line r23aJ in FIG.

In this embodiment, the contact portion 27 has an outer diameter of 40 mm and an inner diameter of 2 mm.
0 mm, it is formed by infiltrating a porous sintered body of Mo-Cr with CuJe.

The arc part 21 has an outer diameter of 80mm, the number of spiral grooves (=the number of arc pedals 21a) is 12, the width of the spiral groove 23 is 4ffI+l+, and is made of Cu (Cu) infiltrated into a porous sintered body of Fe and Cr. 50%) Fe (42%) - Cr (8%)
It must be made of a material consisting of the following ingredients:

As shown in FIG. 4, the electrodes having the above configuration are fixed electrodes 29,
A vacuum interrupter was constructed as the movable electrode 30, and the current interrupting performance was tested by changing the electrode diameter. The results are shown in FIG.

In FIG. 4, the constituent members of the vacuum interrupter are the same as those shown in FIG. 9, and the same members are designated by the same reference numerals. Note that the test conditions were a voltage of 12 kV and an interelectrode gap of 12 mm.

During energization and immediately after contact opening (while the arc exists on the contact surface)
In this case, most of the current paths between the lead rod 25 and the contact surface 27b (Iv)Ih) are perpendicular to the contact surface 27b (indicated by the circles in FIGS. 2 and 10), so when the current path is cut off, Due to the self-diffusion force of the resulting metal vapor, the arc spreads in the radial direction, moves from the contact area to the gap area, and is rotated and extinguished by the action of the spiral groove in the arc area.

In FIG. 1, the movement of the arc is illustrated by an arrow A.

As a result of the test, the interrupting performance of the vacuum interrupter using the electrode of the present invention (indicated by o - o in Fig. 5) was 10% lower in the valley diameter than that of the conventional product (indicated by X - x in Fig. 5).
-30% good results, and extremely good results were obtained even with a large diameter of 120++++a.

When the component is Ih, make sure that Iv>Ih,
The arc moves from the contact part to the arc part by the self-diffusion force of the metal vapor generated when the current is cut off, and the entire arc rotates at the arc part to extinguish the arc, improving the breaking performance and making effective use of the electrode surface. This makes it possible to reduce the electrode diameter and, in turn, reduce the size of the vacuum interrupter. In addition, since the shield is prevented from becoming dirty and the occurrence of flakes, the withstand voltage can be improved and the number of times the large current can be cut off can be increased.

[1 Effects of the Invention The magnetically driven electrode for a vacuum interrupter according to the present invention has the outer diameter of the contact portion set to the diameter of the lead rod, and the lead rod is directly connected to the back surface of the contact portion, so that at least when energized, The current component in the current path formed between the contact surface of the contact part and the rod is expressed as Iv, the component in the direction perpendicular to the contact surface, and Iv in the direction parallel to the contact surface.

[Brief explanation of the drawing]

FIG. 1 shows f for a vacuum interrupter according to an embodiment of the present invention.
2 is a plan view of the 4 poles, FIG. 2 is a sectional view taken along arrows -■, FIG. 3 is a sectional view similar to FIG. 2 of an electrode according to another embodiment, and FIG.
The figure is a longitudinal cross-sectional view of a vacuum interrupter equipped with electrodes according to the embodiment, Figure 5 is a graph showing the relationship between electrode diameter and interrupting performance, Figure 6 is a plan view of a conventional magnetically driven electrode, and Figure 7 Figure 8 is a graph showing the relationship between the diameter of one conventional electrode and breaking performance, Figure 9 is a schematic diagram of a vacuum interrupter, and Figure 10 is an explanatory diagram of the current path. It is. In the drawing, 21 is an arc portion, 23 is a spiral groove, 25 is a U-shaped rod, and 27 is a contact portion. Fig. 1 Example 1: Planar mouth patent for such electrode Applicant Meidensha Co., Ltd. Agent

Claims (1)

[Claims] A vacuum formed by providing a contact portion having a ring-shaped contact surface in the center of one surface of an arc portion having a plurality of spiral grooves, and connecting a lead rod to the center of the other surface. In the magnetically driven electrode for an interrupter, the outer diameter of the contact surface is set to be equal to or less than the diameter of the lead rod, and the lead rod is directly connected to the back surface of the contact part,
At least when current is applied, a current component in a current path formed between the contact surface and the lead rod, where the component in the direction perpendicular to the contact surface is Iv, and the component in the direction parallel to the contact surface is Ih, An electrode for a magnetically driven vacuum interrupter, characterized in that Iv>Ih.