JPH02201833A - Magnetic driving type electrode for vacuum interrupter - Google Patents

Abstract

PURPOSE:To improve the breaking performance by setting a component of the crossing direction to the contact surface to be larger than a component of the parallel direction for current ways formed between a contact surface of a contact part and a lead rod at the time of energization, and extending inner ends of spiral grooves provided in an arc surface to the back part of the contact part. CONSTITUTION:At arc pat 30 of an electrode has a plurality of spiral grooves 29, and a contact part 31 having a ring-like contact surface 31a is connected at the center of the surface side of the arc part 30 by brazing. The spiral grooves 29 of the arc part 30 extend to the back surface side of the contact part 31. A lead rod 32 is connected at the center of the back surface side of the arc part 30 by brazing. The outer diameter of the lead rod 32 and the outer diameter of the contact part 31 are almost similar, and current ways in the crossing direction to the contact surface 31a are thus secured large at the time of energization. Most of current ways between the lead rod 32 and the contact surface 31a are of the crossing direction to the contact surface 31a at the time of energization and just after opening, and arc spreads radially by force of self-diffusion of metal stream produced at the time of breaking to be extinguished after rotation and moving by action of the grooves 29.

Description

DETAILED DESCRIPTION OF THE INVENTION Field 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, in a current path formed between a contact surface and a lead rod, a current component in a direction perpendicular to the contact surface is The contact part, the arc part, and the lead rod are connected to each other in such a way that they are larger than those parallel to the contact surface, and furthermore, the contact surface of the contact part and the surface of the arc part are made into a continuous surface, and a The inner end of the spiral groove is extended to the back of the contact part, 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 in the arc part and broken. This is what I did.

C1 Prior Art In general, as shown in FIG. 8, a vacuum interrupter includes a fixed lead rod 3 having a fixed electrode 2, a movable lead rod 5 having movable poles 4, and movable up and down, as shown in FIG. It is composed of the interior. 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 includes a contact portion 11 provided at the center of one surface of an arc portion 10 provided with a plurality of spiral grooves 9, and a lead rod 12 provided on the other surface of the arc portion 10. It has a connecting structure and aims 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.

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

That is, after the arc 13 occurs at point 2 in FIG. 5, it moves over the arc pedal 10a at points 2 and 3.

■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, conventionally, in order to generate a large magnetic force F, a: The inner diameter of the contact portion 11 is made larger than the diameter of the lead rod 12. b: The upper part of the lead rod 12 is made of a high-resistance material (SUSm). C: The inner end of the spiral groove 9 is extended below the contact portion 11 as shown by 9a in FIG. 5 to lengthen the arc pedal 10a. , ■ For rotational movement of the arc, a: Make the tip of the arc pedal 10a longer as shown by 10b in Fig. 5 to make it easier for the arc to move to the adjacent pedal, b; Gap size with the surrounding arc pedals. We are taking measures such as taking into consideration the following.

D. Problems to be Solved by the Invention The idea behind conventional electrodes that take the above-described 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 part of the m1m 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 in particular, with the measures ① and ②, another problem arises in that durability is reduced.

FIG. 7 shows the relationship between the electrode diameter and current cutoff performance in a conventional electrode. The figure also shows the S pole of the vertical magnetic field application type. 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 becomes 50 kA or more, the arc energy becomes large, so the local concentration of the arc cannot be prevented by magnetic driving force alone, and the m pole diameter is 110 to 120 kA.
If the thickness exceeds mm, the breaking performance will hardly improve.

Furthermore, in a vacuum incluctor with a rated voltage of about 12 kV, the distance from the external wiring (indicated by "l" in Figure 8) is about 250 to 350 meters, and the electromagnetic force is about 20 kV.
Gauss/ k A -rrtra (magnetic flux density/
current/arc length), magnetic driving force F is 10gf/kA-I
Since the arc is about II11, especially when the arc is
If the arc is located near the outer periphery of 0a (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 returned to the original point that the arc generated by the self-diffusion force of the metal vapor generated during the cutting An attempt was made to see if it was possible to move it 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 contact portion, arc portion, and lead rod are arranged so that the majority of the current path between the lead rod and the contact surface of the contact portion is perpendicular to the contact surface (indicated by the circle in Figure 9). By configuring the connection, 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. Furthermore, 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 (in contrast to the previous model, there was only local erosion). ). 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, 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.

Note that in order to smoothly move the arc from the contact portion to the arc portion by self-diffusing force, it is necessary that there be no cuts or the like between the contact surface and the surface of the arc portion. This is because if there is a minute gap at the boundary between the contact surface and the surface of the arc part, or if solder from brazing protrudes, the arc will stagnate at that part and melt the electrode.

Therefore, in addition to connecting the arc part, the connecting part, and the lead rod as described above, the contact surface of the contact part and the surface of the arc part are made into a continuous surface, and the inside of the spiral groove of the arc part is designed to guide the arc. It is effective to extend the end to the contact portion side.

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 magnetic drive type *tWi for a vacuum interrupter in which a lead rod is connected to the central part, at least when current is applied, a current component in a current path formed between the contact surface of the contact part and the lead rod,
When 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, the contact portion, the arc portion, and the lead rod are connected and configured so that Iv>Ih, and further, the contact portion The contact surface of the arc portion and the surface of the arc portion are made continuous, and the inner end of the spiral groove provided in the arc portion extends to the back of the contact portion.

The contact portion is 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 a magnetic material and copper, and a composite metal of Fe-Cr or magnetic stainless steel-Cu is used.

F Function In the vacuum interrupter electrode described above, when the current is interrupted, the generated can arc moves from the contact part to the arc part by the self-diffusion force of the generated metal vapor without causing arc concentration, and each arc in the arc part Since the whole 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 a cross section thereof taken along the line 1--2.

The arc portion 30 of the electrode has a plurality of spiral grooves 29. A contact portion 31 having a ring-shaped contact surface 31a is coupled to the center portion of the front surface of the arc portion 30 by brazing. The spiral lI29 of the arc portion 30 extends to the back side of 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 this lead rod 32 and the outer diameter of the contact portion 31 are approximately equal. By doing so, a large current path in the direction perpendicular to the contact surface 31a is ensured, at least when the current is applied.

The arc portion 30 and the contact portion 31 are connected by brazing as described above, but after the two are connected by brazing, the contact surface 3
81 to make 1a and arc portion surface 30a a continuous surface.
Castle processing is applied. Contact surface 31a and arc portion surface 30a
By making these continuous surfaces, the arc can smoothly move from the contact surface 31a to the arc portion surface 30a.

In this electrode, a reinforcing plate 35 made of stainless steel, Inconel, 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 2 mm.
Cujeil is applied to the porous sintered body of Mo-Cr between 0 and 0.
Formed by soaking.

The arc part 30 has an outer diameter of 80 mm, the number of spiral grooves (=the number of arc pedals 30b) is 12, and the width of the spiral groove 29 is 4 mm. 50%) Fe (42%) - Cr (8%).

As shown in FIG. 3, the electrodes with the above configuration are fixed electrodes 33,
A vacuum interrupter was constructed as the movable electrode 34, and the current interrupting performance was tested by changing the electrode diameter. The results are shown in FIG.

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 12 kV and an interelectrode gap of 12 mm.

During energization and q opening M1& (while the arc exists on the contact surface 31a), the current path between the lead rod 32 and the contact surface 31a is connected to the contact surface 31. Since the majority (Iv>Ih) is orthogonal to a (indicated by the circles in Figures 2 and 9), the self-diffusion force of the metal vapor generated at the time of interruption causes the arc to spread in the radial direction and cause contact. It moves from part to arc part, rotates and extinguishes the arc by the action of the spiral groove in the arc part. Further, since the contact surface 31a and the arc portion surface 30a are continuous surfaces, and there is nothing that could cause stagnation of the arc, the contact surface 31. The movement of A from a to the arc portion surface 30a is performed smoothly. In FIG. 1, the movement of the arc is illustrated by arrow A.

As a result of the test, the breaking performance of the vacuum interrupter using the electrode of the present invention (indicated by o --- o in Fig. 4) was 10% lower in the valley diameter than that of the conventional product (indicated by × - × in Fig. 4). -30% good results, and extremely good results were obtained even with the large diameter one of 120 mm.

It Effects of the Invention The magnetically driven vacuum interrupter electrode according to the present invention has the following effects:
At least when energized, the current component in the current path formed between the contact surface of the contact part and the rod is 1v in the direction perpendicular to the contact surface, and 1v in the direction parallel to the contact surface. The contact part, the arc part, and the lead rod are connected so that Iv>Th when Ih is applied, and the contact surface of the contact part and the surface of the arc part are continuous, and a By extending the inner end of the spiral groove to the back of the contact part, 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 in the arc part to extinguish the arc. Therefore, the interrupting performance is improved and the electrode surface can be used effectively, making 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.

[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 - - from t, and Fig. 3 is a longitudinal cross-section of a vacuum interrupter equipped with an electrode according to an embodiment. 4 is a graph showing the relationship between electrode diameter and cutting performance, FIG. 5 is a plan view of a conventional magnetically driven electrode, FIG. 6 is a cross-sectional view taken along the ■-■ arrow, and FIG. A graph showing the relationship between the electrode diameter and breaking performance of a conventional electrode, FIG. 8 is a schematic diagram of a vacuum interrupter, and FIG. 9 is an explanatory diagram of a current path. In the drawing, 29 is a spiral groove, 30 is an arc portion, 30a is a surface of the arc portion, 31 is a contact portion, 31a is a contact surface, and 32 is a lead rod. Fig. 1: Plan view of the electrode according to the embodiment Fig. 2: Cross-sectional opening along line I-I in Section 1; Figure 9: Explanatory diagram of current path

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, at least when current is applied, a current component in a current path formed between the contact surface of the contact portion and the lead rod,
When 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, the contact portion, the arc portion, and the lead rod are connected and configured so that Iv>Ih, and further, the contact portion A magnetically driven electrode for a vacuum interrupter, characterized in that the contact surface of the part and the surface of the arc part are continuous surfaces, and the inner end of the spiral groove provided in the arc part extends to the back of the contact part. .