JPH01173531A - Vacuum interrupter - Google Patents

Abstract

PURPOSE:To improve the breaking performance on opened poles nearby at the time of the current peak by uniformly providing disk-shaped protruded contact sections with the same height over the peripheral direction at positions slightly outside than the outer diameter size of lead bars on the surfaces of plane electrodes and specifying the number, diameter and height of them to constitute at least one electrode. CONSTITUTION:Disk-shaped protruded contact sections 14a and 15a with the same height are uniformly provided over the periphery direction at positions slightly outside than the outer diameter size of lead bars on the surfaces of electrodes 14 and 15 having nearly plane surfaces, the number of the protruded contact sections 14a and 15a is set to 3-6, the diameter is set to 3-8mm, and the height is set slightly smaller than the diameter to constitute at least one electrode. The electrodes 14 and 15 are brought into contact with each other via the protruded contact sections 14a and 15a of one electrode, thus they are in contact at least at three points, as a result distributed arcs occur at the contacts, the magnetic driving force in the radial direction is applied to these arcs and moves them to the arc diffusion section on the periphery. The preset breaking can be satisfactorily performed on opened poles at the peak time of a large current.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a vacuum interrupter, and more particularly to a so-called vertical magnetic field application type vacuum interrupter equipped with a coil that generates an axial magnetic field parallel to the axis. It is something.

B. Summary of the Invention The present invention provides a vacuum interrupter using a vertical magnetic field application method.
Disk-shaped convex contact portions of the same height are provided at positions slightly outward from the outer diameter dimension of the lead rod on the surface of the electrode having a substantially flat surface, equidistributed over the circumferential direction. , the number of these convex contact parts is 3 to 6, the diameter is 3 (mm) to 8 (臘),
at least one electrode is configured with a height smaller than the diameter;
By applying a horizontal magnetic driving force to the arc and applying a vertical magnetic field, good interruption can be achieved even at the current peak electrode when interrupting a large current.

C9 Prior Art As a type of vacuum interrupter, there is a so-called vertical magnetic field application type vacuum interrupter that has a coil that generates an axial magnetic field parallel to the arc.

This vertical magnetic field application type vacuum interrupter uses the axial magnetic field (w! magnetic field) to disperse the arc on the electrode surface and prevent its local concentration. It is known for its excellent current interrupting performance and high withstand voltage characteristics.

However, even in the vertical magnetic field application type vacuum interrupter, there is a problem in that current interrupting performance deteriorates depending on the opening timing.

That is, in the case of opening near the current peak time when the arc energy is the largest, that is, in terms of arc time, it is 50 Hz.
The period before and after the 0.25 period point (approximately 0
．． In the case of opening during a period of 2 cycles to 0.3 cycles, there is a problem in that the cut-off current value decreases significantly.

In order to solve this problem, an improved electrode structure of a vertical magnetic field application type vacuum interrupter has been proposed. This electrode is shown in Fig. 5 (al) and Fig. 5 (b). As shown in both figures, the electrode 1 has an annular shape on its surface whose inner diameter is approximately equal to or slightly larger than the outer diameter of the lead rod 2. It has a convex contact part 1a and an arc diffusion part 1b around the convex contact part 1a, and the magnetism directed outward in the radial direction of the electrode 1 is generated by forming a U-shaped current path I. The driving force F causes the arc A generated at the initial stage of contact opening to be rapidly moved from the convex contact portion 1a to the outer arc diffusion portion 1b.

D. Problems to be Solved by the Invention In the prior art as described above, even when an arc driving method using magnetic driving force is used in combination with the method of applying a vertical magnetic field,
In the case of opening at the current peak, the current interrupting performance is 1.5
It only improves by about twice as much.

Therefore, when we experimentally tracked down the factors that restrict the interrupting performance of the above-mentioned vacuum interrupter combined with magnetic driving force, we found the following.

That is, the arc A generated at the time of contact opening is quickly moved from the convex contact portion 1a to the arc diffusion portion 1b to alleviate thermal concentration at the arc generation point, but as the breaking current increases, the heat Even if the magnetic gFc driving force F that moves the arc in the radial direction is applied, the thermal concentration remains in the thermally concentrated area and opens with a rough surface, resulting in a re-electromotive voltage. It was found that this caused flash shorting from the convex contact portion 1a, and that the breaking performance near the peak current was not improved.

In view of the above experimental results, the present invention has developed a vacuum interrupter that has improved breaking performance at rMti near the current peak, which is the most severe breaking condition when large current is cut off in a vacuum interrupter using a vertical magnetic field application method. The purpose is to provide.

E. Measures to solve the problem In general, during use, the electrodes of the vacuum incluctor include:
A pressure contact force that resists the electromagnetic repulsive force is constantly applied to keep the contact resistance value below a predetermined value to suppress heat generation due to energization.

It is also possible to calculate the number of contact points based on the contact resistance value, and the following formula is known.

However, R = contact resistance (actual measurement), ρ = specific resistance value of electrode 1, a = radius of the contact area between electrodes 1, H = Brinell hardness of electrode 1. Therefore, the relationship between pressure contact force P and contact resistance value R I looked into it. The t1 pole used was 49Cu-38Mo-13Cr
(% by weight) of composite material.

First, an investigation was conducted on a non-energized and uncut electrode (a new electrode), and the results shown in FIG. 6 were obtained.

That is, in the elastic range where the pressure contact force P is small, the contact resistance value is high;
Gradually decreases as shown by the straight line ■ in the figure (R P3)
Shita. When the pressure contact force P is increased, it becomes a plastic region, and the contact resistance value rapidly decreases as shown by the straight line 1 [, II (R P2
゜RccP-1)L, ta.

On the other hand, when the electrode (used electrode) after several times of large current interruption and large current energization was investigated, the results shown in FIG. 7 were obtained.

That is, it has been found that the relationship between the pressure contact force P and the contact resistance value R is similar to the above-mentioned straight line (RocP2).

This is presumed to be due to the fact that the electrode is subjected to the load of cutting off and energizing, so that a certain thickness of the surface side of the electrode loses its elastic region and becomes a plastic region.

Based on the above results, the number of contact points was calculated using the above formula, and it was found that for new electrodes, the number of contact points n was 2 to 5 points, and in particular, more than half of the contact points were 3 points. On the other hand, it was found that there was only one point for the electrode after defecation.

From the above results, if the number of contact points n is reduced, especially to one point, the electrode surface will become excessively rough due to the arc during contact opening, leading to a decrease in the breaking performance. Furthermore, a small number of contact points leads to an increase in contact resistance, which causes a problem of heat generation during energization.

Therefore, the configuration of the present invention includes a pair of lead rods introduced into a vacuum container so as to be able to approach and separate from each other, a pair of electrodes fixed to the inner ends of the lead rods and facing each other, and an arc In a vacuum interrupter having a coil that generates an axial magnetic field parallel to the lead rod, a circumferential wire is placed on the surface of the electrode having a substantially flat surface at a position slightly outward from the outer diameter dimension of the lead rod. Disk-shaped convex contact portions of the same height are provided equally spaced in the direction, and the number of convex contact portions is 3 to 6 and the diameter is 3 (mn+) to 8.
(mm 2 ), the height of which is smaller than the diameter of at least one electrode.

F Effect According to the present invention having the above configuration, since the electrodes contact each other via the convex contact portion of one electrode, they contact each other at at least three points, and as a result, a distributed arc is generated at each contact point, and A radial magnetic driving force acts on this arc and moves it to the surrounding arc diffusion area, so that no thermal aftereffects are exerted on the convex contact area.

Embodiment G The present invention will be described in detail below based on an embodiment shown in the drawings.

As shown in FIG. 1, the vacuum ink cleaner of this embodiment is
A fixed lead rod 12 and a movable lead rod 1 are placed inside the vacuum container 11.
3 are introduced so as to be relatively approachable and releasable, and electrodes 14 and 15 are fixed to the inner ends of the fixed and movable lead rods 12 and 13, and the vacuum vessel 11 is connected to [! A longitudinal magnetic field in a direction parallel to the arc generated between the electrodes 14 and 15 is applied by the coil 16 extending therethrough. In the figure, 17 is an arc shield, and 18 is a metal bellows, which allows the movable lead rod 13 to move up and down.

Figure 2 (al is electrode 1 of the vacuum interrupter shown in Figure 1)
Front view extracting and showing 4.15 and its neighboring parts, 2nd
Figure (bl is a view taken along the line A-A. As shown in both figures, the electrodes 14 and 15 having substantially flat surfaces are made of a composite metal of Cu and a high melting point material, Its component ratio is Jusha%: Cu = 49%, Mo = 38% 1Cr = 13
%. In addition, in this embodiment, the fixed lead rod 1
Three cylindrical convex contact portions 14a are formed on the surface of one of the electrodes 14 fixed to the electrode 2 at positions slightly outward from the outer diameter of the fixed lead rod 12 and equally spaced in the circumferential direction. It is. These convex contact portions 14a are each formed to have the same height and a base having a certain degree of curvature, preferably a continuous curvature with the arc diffusion portion 14b which is a plane other than the convex contact portion 14a.

Note that the number of convex contact portions 14a is set to 3 to 6 in view of the fact that the number of contact points was 2 to 5 from the above-mentioned experimental results.

Further, the diameter of the convex contact portion 14a is 3 mi to 8 thresholds, preferably 5+m. This means that when focusing on one contact point of the electrode 14, the diameter of the contact portion must increase as the applied current increases;
This is based on the experimental results that the temperature is saturated at ).

Further, the height h of the convex contact portion 14a may be at least as long as the electrode is consumed, and may be smaller than the outer diameter. Further, when paying attention to the material of the electrode 14 as described above in this embodiment, T1
Since the amount of extreme consumption is small, 0 < h < 1 (
mn), preferably 0.5 mm. In addition, mTi
It is desirable that the height of the convex contact portion 14a be as low as possible in order to keep the surface of the electrode 1ii14 as flat as possible so that the cathode spot due to the first field is easily distributed evenly on the surface of the electrode 14.

On the other hand, the other electrode 15 fixed to the movable lead rod 13 has a convex contact portion 15 opposite to the convex contact portion 14a of the electrode 14.
It has a. These convex contact portions 15a have a diameter slightly larger than that of the convex contact portion 14a.
.

The configuration is the same as that of the convex contact portion 14a except that the contact of the contact portion 15a is ensured.

Note that the surface of the electrode 15 may remain flat; the point is that at least one electrode should be provided with a convex contact portion, and if a pair of electrodes are provided with a convex contact portion, the convex contact portion on one side should be provided with a convex contact portion. The outer diameter of the contact portion may be increased so that it comes into contact with the surface.

According to this embodiment, the electrodes 14 and 15 are connected to the convex contact portion 1.
Since they are in contact at three points via 4a and 15a, the vacuum interrupter's rJ! At the J pole, a magnetic driving force acts on the arc at each contact point, which is a dispersed arc, and each arc quickly moves to the arc diffusion area, and a longitudinal magnetic field acts on the many generated arcs, causing the arc to be in a dispersed state. is maintained. Therefore, even when the contact is opened at the peak of a large current, the convex contact portion 14
A, 15a does not cause any thermal aftereffects due to the arc.

In the above embodiment, the coil for generating the vertical magnetic field was arranged outside the vacuum vessel 11, but the fill may be located near the electrode or at the back of the electrode. In short, the present invention only needs to be of a type that generates a vertical magnetic field.

FIG. 3 (al is an electrode according to the present invention, FIG. 3(b) is a disc-shaped electrode, and FIG. 3(e) is an M F with a ring-shaped contact portion on which a magnetic driving force acts. [I are shown respectively, and FIG. 4(a) to FIG. 4(C) are shown in FIG. 3(a) to
FIG. 4(a) is a characteristic diagram showing the blocking property (new blocking area) of a vertical magnetic field application type vacuum interrupter having each electrode shown in FIG. 3 (tel), and FIG. Figure (b)
corresponds to Fig. 3 (b) and Fig. 4 (cl corresponds to Fig. 3 (cl), respectively, and the lowest value of the cutoff current value in Fig. 4 [b) is compared as 100%. be.

As shown in Fig. 4(a), the present invention has a 180% cut-off performance even when the current peak is open (0.25 cycles), and the cut-off performance varies depending on the σ target timing. It can be seen that the large current can be cut off well without being damaged.

■ [Effects of the Invention As explained above in detail with the embodiments, according to the present invention, since a pair of electrodes are in contact with each other through three to six convex contact portions, arcing at the time of opening is prevented. The arc is dispersed at each contact point, and as a result of the magnetic driving force acting on each arc, no thermal aftereffects occur at the convex contact part of the electrode, and a longitudinal magnetic field acts on the arc that occurs thereafter. Since the arc is maintained in a dispersed state, even when the arc is opened at the peak of a large current, a predetermined breaking can be performed satisfactorily. Therefore, regardless of the opening timing,
It can cut off large currents reliably, fully exhibit the longitudinal magnetic field effect, and contribute to downsizing of vacuum interrupters.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention, FIG.
bl is a view taken along the line A-A in Fig. 2(a), and Fig. 3(a) -
FIG. 3(C) is a front view showing each electrode, FIG. 4 ta+ to FIG. A front view showing the If pole of such a vacuum interrupter, FIG. 5 (bl is a plan view thereof, and FIG. 6 → shows the relationship between pressure contact force and contact resistance value when the electrode is new as shown in ml and fbl) Characteristic diagram, Figure 1 shows the same relationship after several times of energization and shutoff.In the diagram, 11 is a vacuum container, 12 is a fixed lead rod, 13 is a movable lead rod, 14.15 is a Electrodes, 14a and 15a are convex contact parts, and 16 is a coil.Patent applicant Meidensha Co., Ltd. Agent

Claims (1)

[Claims] A pair of lead rods are introduced into the vacuum chamber so that they can be moved toward and away from each other, a pair of electrodes are fixed to the inner ends of the lead rods and are opposed to each other, and an axial direction parallel to the arc is formed. In a vacuum interrupter having a coil that generates a magnetic field, on the surface of the electrode having a substantially flat surface, at positions slightly outward from the outer diameter dimension of the lead rod, evenly distributed circumferentially and at the same height. A disc-shaped convex contact part is provided,
The number of these convex contact parts is 3 to 6, and the diameter is 3 (mm) to 8.
(mm), and at least one of the electrodes is configured to have a height smaller than a diameter.