JPH02201830A - 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 a contact part, an arc part, and the lead rod with each other in such a way that a component crossing the contact surface is larger than a parallel component for current components of current ways at the time of energization. CONSTITUTION:An arc part 30 of an electrode has a plurality of spiral grooves 29, and a ring-like contact part 31 is connected at the center of the surface side of the arc part 30 by brazing, and the spiral grooves 29 of the arc part 30 are extended to the contact part 31. Most of current ways between a lead rod 12 and a contact surface 31a are of the crossing direction to the contact surface 31a at the time of energization and just after the opening time (while arc exists in the contact surface), the arc spreads radially by force of self- diffusion of metal steam produced at the time of breaking to move from the contact part 31 to the arc part 30, and the arc is extinguished after rotation and moving by action of the spiral grooves 29 at the arc part 30. The breaking performance is thus made much better than that of the conventional devices.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field 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 a magnetically driven electrode for a vacuum interrupter in which the outer diameter of the contact surface is the same as the diameter of the lead rod, and the current path formed between the contact surface and the lead rod. Of the current components, the current component in the direction perpendicular to the contact surface is made larger than the current component parallel to the contact surface, so that the arc is moved from the contact part to the arc part by the self-diffusion force of the arc due to metal vapor at the time of interruption, and the arc The arc is cut off by rotationally moving the arc.

2. Description of the Related Art In general, a vacuum interrupter has a fixed lead rod 3 having a fixed electrode 2 and a movable M pole 4, as shown in FIG. It is constructed by incorporating the rod 5. In the figure, 6 is a bellows that makes the movable lead rod 5 movable, and 7 is a shield that covers the inner circumference of the vacuum container 1.

The electrodes 2 and 4 of such a vacuum interrupter are required to have various 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.

An example of a magnetically driven electrode is shown in FIGS. 5 and 6. 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, painstaking efforts are made to ensure that the generated arc does not stagnate and continues to move until the current reaches zero point.

After the arc 13 occurs at ■ in Fig. 5, it moves on the arc pedal 10a by ■ 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 electric rod 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, a: the inner diameter of the contact portion 11 was made larger (compared to the diameter of the lead rod 12), b: a high-resistance material (SO3 C: The inner end of the spiral groove 9 is extended below the contact part 11 as shown by 9a in FIG. 5, and the arc pedal 10a is extended (
For rotational movement of the arc, the tip of the arc pedal 10a is lengthened as shown by 10b in Figure 5 to make it easier for the arc to move to the adjacent pedal. Measures are taken to: (b) consider the gap size with the surrounding arc shield;

D. Problems to be Solved by the Invention The idea behind conventional electrodes that take the above-mentioned measures is to quickly apply a magnetic driving force by a so-called U-shaped force to the generated arc 13. Therefore, the movement of the arc 13 is such 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 13' and rotate.

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 portion of the electrode surface, and the entire electrode surface 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, and measures ① and ③ cause another problem of reduced durability.

FIG. 7 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, with magnetically driven electrodes, if the electrode diameter exceeds a certain size, no improvement in the blocking 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.
Above m+a, 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 8) is on the order of 250 to 350, and the electromagnetic force is about 20 kV.
0aug+/kA-III11 (magnetic flux density/current/arc length), magnetic driving force F is 10 g f/k A-
ms, so the arc is particularly strong when the arc pedal 10a
If the arc is located near the outer periphery (the position marked with ■ in FIG. 5), it becomes difficult for the arc to move in the circumferential direction, and the breaking performance deteriorates.

As mentioned above, there was a limit to the improvement of the breaking performance by the outward magnetic driving force, so the inventors of the present invention went back to the basics and decided to reduce the arc generated by the self-diffusion force of the gold-g4 vapor generated at the time of cutting. I tried to see if it could be moved from the contact area to the arc area.

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 surface is set to be less than or equal to the diameter of the lead rod, and in most cases the current path between the lead rod and the contact surface is perpendicular to the contact surface (indicated by a circle in Figure 9). In this way, consideration was given to minimizing the component in the direction parallel to the contact surface (indicated by O in FIG. 9).

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. Moreover, when we disassembled the product after the test and observed the electrode surface, we found that there was no local erosion, and traces of arcing were seen over almost the entire electrode surface (conventional products had only two localized lotions). Ta). 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 indicates 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, better 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.

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 in the center of the other surface. In a magnetically driven electrode for a vacuum interrupter in which a lead rod is connected to a portion of the electrode, the outer diameter of the contact surface is less than or equal to the diameter of the lead rod, and the electrode is formed between the contact surface and the lead rod at least when energized. In the current path, the current component in the direction perpendicular to the contact surface is IV, and the component in the direction parallel to the contact surface is Ib. The rods were connected and configured.

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

Further, the arc portion is made of a material mainly composed of magnetic material and copper, such as Fs-Cr or magnetic stainless steel ll-Cu (
D97 alloy metal is adopted.

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

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

The arc portion 30 of the electrode has a plurality of spiral grooves 29. A ring-shaped contact portion 31 is coupled to the center portion of the surface side of the arc portion 30 by brazing. In this electrode, the spiral groove 29 of the arc portion 30 extends to the contact portion 31.

A beam rod 32 is joined to the center portion of the back side of the arc portion 30 by brazing. The outer diameter of the contact portion 31 is set to be less than or equal to the diameter d of the rod 32. By doing this, at least when electricity is applied, the contact surface 31a
This ensures a large current path in the direction perpendicular to (the surface of the contact portion 31). Incidentally, if the outer diameter of the contact surface 31a is made larger than the diameter d of the lead rod 32, the current path O component in the direction parallel to the contact surface 31a increases as the outer diameter increases, and the current ih increases.

In this electrode, a reinforcing plate 35 made of stainless steel, innel, etc. is provided on the back surface of the arc portion 30.

In this embodiment, the contact portion 31 has an outer diameter of 40 mm and an inner diameter of 20 mm.
+mn, it is formed by infiltrating Cu into a porous sintered body of Mo-Cr.

The arc part 30 has an outer diameter of 80 mm, the number of spiral grooves (in addition to the number of arc pedals 30a) is 12, and the width of the spiral groove 29 is 4 mm.
It is formed from a material consisting of the following components: u (50%) - Fe (42%) - Cr (8%).

As shown in FIG. 3, the electrodes with the above configuration are fixed electrodes 33,
Configure a vacuum interrupter as a possible rjJJ electric rod 34,
Figure 4 shows the results of testing the current interrupting performance by changing the electrode diameter.

In FIG. 3, the constituent members of the vacuum interrupter are the same as those shown in FIG. 8, and the same members are designated by the same reference numerals. Note that the test conditions were a voltage of 1.2 kV and an interelectrode gap of 12 mm.

During energization and immediately after opening 8ii (while the arc exists on the contact surface), the current path between the lead rod 12 and the tangential surface 31a is perpendicular to the contact surface 31a (Fig. 2, 9).
(indicated by the circle in the figure) is the majority (Iv>Ih), so the arc spreads in the radial direction due to the self-diffusion force of the metal vapor generated at the time of interruption, moves from the contact part to the arc part, and forms a spiral groove in the arc part. It rotates and moves due to the action, causing an arc-extinguishing gap. In FIG. 1, the movement of the arc is illustrated by an arrow A.

As a result of the test, the breaking performance of the vacuum interrupter using the electrode of the present invention (indicated by 0-0 in Fig. 4) was 1 higher in the outer diameter than that of the conventional product (indicated by ×-× in the 4th rIA).
The results were 0 to 30% good, and extremely good results were obtained even with the large diameter 120%.

■ Effects of the Invention In the magnetically driven electrode for a vacuum incluctor according to the present invention, the outer diameter of the contact surface of the contact portion is equal to or less than the diameter of the lead rod, and at least when electricity is applied, the magnetically driven electrode for a vacuum incluctor is formed between the contact surface and the lead rod. When the current component in the current path is Iv, the component in the direction perpendicular to the contact surface, and Ih, the component in the direction parallel to the contact surface, the contact part, arc part, and lead rod are connected so that Iv>Ih. Then, 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. This improves the breaking performance and makes the electrode surface Since it can be used effectively, it is possible to reduce the diameter of the electrode and, in turn, reduce the size of the vacuum interrupter. Furthermore, since the shield is less likely to become soiled and the occurrence of flakes occurs, it is possible to improve the withstand voltage and increase the number of times the large current is cut off.

[Brief explanation of the drawing]

FIG. 1 is a plan view of an electrode for a vacuum interrupter according to an embodiment of the present invention, FIG. 2 is a cross-sectional view taken along arrows -■, and FIG. 3 is a vertical cross-section of a vacuum interrupter equipped with an electrode according to an embodiment. Figure 4 is a graph showing the relationship between electrode diameter and cutting performance.
Fig. 5 is a plan view of a conventional magnetic 5A drive type electrode, Fig. 6 is a sectional view taken along the line M-M, Fig. 7 is a graph showing the relationship between the electrode diameter and cutting performance of the conventional electrode, and Fig. 8 The figure is a schematic diagram of the vacuum interrupter, and FIG. 9 is an explanatory diagram of the current path. In the drawing, 29 is a spiral conductor, 30 is an arc part, 31 is a contact part, and 32 is a lead rod. Patent Application Co., Ltd. Osamu Akiyo

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 at least when current is applied, a current component in a current path formed between the contact surface and the lead rod is reduced to the contact surface. A vacuum interrupter characterized in that the contact part, the arc part, and the lead rod are connected so that Iv>Ih, where Iv is the component in the direction perpendicular to the contact surface, and Ih is the component in the direction parallel to the contact surface. Magnetically driven electrode.