JPH08111148A - Vacuum valve electrode - Google Patents

Abstract

(57) [Summary] [Purpose] To obtain electrodes for vacuum valves that can increase the breaking performance and current carrying capacity. [Structure] The electrode 1 in which the center portion of the back surface is joined to the tip of an energization shaft 17 is provided with four arm portions 1a formed radially outward from the center portion, and the tip of this arm portion 1a is The arc-shaped coil portion 1b is formed. An electrode plate 3 is provided on the front surface of the electrode 1, and the electrode plate 3 is provided with protrusions 3b at 90 ° intervals on the outer periphery of the disc portion 3a, and the protrusions 3b are brazed to the tip 1c of the coil portion 1b. To do. The contact 2 is brazed to the front surface of the electrode plate 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum valve electrode, and more particularly to a vacuum valve electrode in which the structure of a longitudinal magnetic field electrode is changed.

[0002]

2. Description of the Related Art An example of the structure of a vacuum valve incorporated in a conventional vacuum circuit breaker is shown in a vertical sectional view of FIG. As shown in FIG. 5, the vacuum valve 10 includes a fixed electrode 14 and a movable electrode 15 in a predetermined space inside a vacuum container configured by sealing both ends of an insulating cylinder 11 with a fixed flange 12 and a movable flange 13. It is confronted with.

Of these, the fixed electrode 14 is the fixed flange 12
It is fixed to the tip of a fixed current-carrying shaft 16 made of a copper rod penetrating the center of the vacuum vessel, and is connected to the outside of the vacuum container via the base end of the fixed current-carrying shaft 16. The movable electrode 15 is fixed to the tip of a movable energizing shaft 17 which is also made of a copper rod, and is connected to the outside of the vacuum container via the lower part of the movable energizing shaft 17.

The movable energizing shaft 17 penetrates a bearing 22 inserted in the center of the movable flange 13, and the lower end thereof is movable flange 13.
Movable flange through the bellows 18 brazed to the inner surface of the
It penetrates 13 airtightly. Therefore, the vacuum valve
The movable electrode 15 can be brought into and out of contact with the fixed electrode 14 by an operation mechanism portion (not shown) connected to the lower end of the movable energizing shaft 17 via an insulating rod (not shown) while maintaining the vacuum in the vacuum container. . The upper end of the bellows 18 is brazed to the upper and lower surfaces of a bellows cover 19 whose upper end is joined to the movable energizing shaft 17, and a cylindrical arc shield 20 is attached to the center of the inner surface of the insulating cylinder 11. .

By the way, since the vacuum valve utilizes the excellent arc extinguishing performance and insulating property of vacuum, compared with a circuit breaker using another insulating medium, for example, sulfur hexafluoride gas as the insulating medium. Thus, the gaps between the electrodes can be close to each other, and the outer shape can be made small. Also, the breaking capacity can be further increased by improving the structure of the electrode as described below.

In order to improve the shutoff performance of the vacuum valve,
It is necessary to suppress the local heating of the electrodes due to the arc generated between the electrodes. Therefore, conventionally, a structure of an electrode capable of suppressing abnormal generation of charged particles and metal vapor due to local heating of the electrode has been studied and put into practical use. As an electrode structure for this purpose, it is general to apply a driving force to the arc generated between the electrodes when the current is cut off by a magnetic field generated by the arc current.

As one of the methods of applying the magnetic field, there is a method of applying a magnetic field in a direction orthogonal to the arc generated between the electrodes. Electrode structures that employ this method include electrodes generally called spiral electrodes and contract electrodes. The magnetic field generated by such an electrode is a magnetic field in the radial direction from the center of the electrode.

Therefore, a Lorentz force acts in the circumferential direction on the arc generated between the electrodes. By this power,
The arc is rotationally driven in the circumferential direction and rotates on the surface of the electrode. By rotating the arc, local heat input can be prevented and melting of the electrodes can be prevented.

However, in order to apply this vacuum valve to a vacuum circuit breaker for breaking a high-voltage circuit, it is necessary to increase the distance between the electrodes in order to improve the withstand voltage between the electrodes. In this case, when the electrode structure for applying a magnetic field in a direction orthogonal to the arc generated between the electrodes described above is used, when the arc rotates on the electrode surface, the arc is stretched in the circumferential direction. Not only is there a possibility that the outer periphery of the electrode will be ejected in the radial direction, but this ejected arc may be ignited to the arc shield attached to the outside of the electrode.

Then, the legs of the arc are stagnated at both ignition positions, and excessive heat input is locally generated to this portion. This excessive heat input melts the electrode and the ignition part of the arc shield, and reduces the breaking performance. Furthermore, in such an electrode structure, as described above, since the arc is a high-temperature concentrated arc, the contact wear is increased,
The switching life of large current is reduced.

As another method of applying a magnetic field for driving the arc generated when the current is cut off, a magnetic field in an axial direction parallel to the arc generated between the electrodes,
That is, there is a method of applying a vertical magnetic field. The electrodes that employ this method are called so-called longitudinal magnetic field electrodes, and the arc generated between these electrodes spreads evenly over the entire opposing surface of the electrodes, preventing local excessive heat input on the electrode surface and interrupting it. An electrode structure with excellent performance can be obtained.

Even when the distance between the electrodes is increased in a vacuum valve connected to a high voltage circuit, a stable arc can be ignited between the electrodes by properly selecting the strength of the longitudinal magnetic field described above. It is possible to improve the blocking performance. Furthermore, since the ignition positions of the arc are dispersed, even when a large current is cut off, the contact wear is small,
The switching life can be extended.

A conventional electrode structure for generating a typical axial magnetic field will be described with reference to the plan view of FIG. It should be noted that FIG. 6 shows a view as seen from the front with the contacts omitted. This electrode is provided with a coil electrode 21 on the back, and this coil electrode 21
A current flowing in 21 generates a magnetic field in the axial direction between the electrodes, that is, a vertical magnetic field. The current flowing through the coil electrode 21 is four arm portions 21a extending radially from the center at 90 ° intervals.
Flow into the arc-shaped curved coil portion 21b from the tip of each arm 21a, and from the tip 21c of the coil 21b to the contact brazed to the tip.

The coil electrodes 21 are attached to the rear surfaces of the contacts on the movable electrode side and the fixed electrode side, respectively, and the above-mentioned axial magnetic field is generated between the electrodes by the current flowing through the coil portion 21b. Although FIG. 6 shows the case where the arm portion 21a is divided into four, the strength of the magnetic field in the axial direction can be changed by changing the number of arm portions.

As another electrode structure for generating an axial magnetic field, as shown in Japanese Patent Publication No. 32007/1990, a spiral slit is formed in the cylindrical portion of a cup-shaped electrode to generate an axial magnetic field. Structures to generate are proposed. In this electrode, by forming the current path of the cylindrical portion in a spiral shape, a circumferential component of the current is generated, thereby generating an axial magnetic field between the electrodes. The strength of the magnetic field in the axial direction can be changed by changing the inclination of the slit formed in the cylindrical portion.

[0016]

In order to apply the vacuum circuit breaker to a large capacity power system, it is necessary to increase the breaking capacity and the current carrying capacity. In response to this demand, the structure of the electrodes and the contact material have been improved, and as the contact material, a special alloy such as a copper-chromium alloy has been developed.

On the other hand, as a result of investigating the relationship between the strength of the magnetic field and the arc voltage from the research of the electrode structure of the longitudinal magnetic field that generates a magnetic field parallel to the arc generated between the contacts, the arc voltage has the lowest value at a certain magnetic field strength. It has been revealed that By applying the magnetic field strength at which the arc voltage exhibits the lowest value, the arc energy consumed between the contacts is minimized and the breaking performance is maximized.

The magnetic field strength at which the arc voltage becomes the minimum depends on the diameter of the electrode, the breaking current, the contact material, etc., and it is necessary to increase the strength of the magnetic field in order to improve the breaking performance. In the electrode structure for generating a magnetic field in the axial direction by using the coil electrode shown in FIG. 6, it is possible to increase the strength of the magnetic field by increasing the arc-shaped component of the current described above by reducing the number of the arms 21a. For example, by reducing the number of arms 21a from four to three and two, the magnetic field strength increases to about 1.3 times and two times, and it is possible to obtain the optimum magnetic field strength for the blocking condition. Performance can be improved.

However, in such a method of increasing the magnetic field strength, the current-carrying path becomes long, so that the resistance at the coil electrode portion increases. As a result, there is a possibility that the temperature rise becomes excessive when the normal load current is applied. Therefore, when the number of arms is reduced, it is necessary to increase the cross-sectional area of each arm and the coil, so that the electrode becomes large and the manufacturing is difficult, and the reliability may be reduced.

Further, when the cross-sectional area of the coil portion is increased to increase the current carrying capacity, the center diameter of the portion that generates the magnetic field is reduced when the outer diameter of the electrode is the same. Therefore, the magnetic field at the electrode end portion decreases, the entire electrode surface cannot be effectively used, and the blocking performance may deteriorate. Furthermore, when the current is cut off, when the arc generated between the electrodes is ignited from the end of the electrode, the arc becomes unstable in the weak magnetic field and the arc becomes unstable. Was extended, the control by the magnetic field of the arc was not effective, and there was a fear that the breaking performance was deteriorated.

Therefore, in view of the above problems, an object of the present invention is to obtain an electrode of a vacuum valve capable of improving the breaking performance and increasing the current carrying capacity without increasing the outer shape.

[0022]

In the electrodes of the vacuum valve according to the present invention as set forth in claims 1, 2 and 3, the center of the back surface is joined to the tip of the current-carrying shaft, and a plurality of current-carrying arms are provided from this center. Parts are formed in a radial shape, and a plurality of protrusions are joined to the front surface of the electrode in which the coil portion is formed in an arc shape from the tip of the energizing arm portion, and the electrode plate formed on the outer circumference of the disk portion is joined to the front surface of the electrode portion. It is characterized in that a disc-shaped contact is joined to the front surface of the electrode plate. Further, it is preferable that the protruding portion of the electrode plate is joined to the tip of the coil portion, and the cross-sectional shape of the contact is frusto-conical with the outer circumference of the top face being a curved surface, and the diameter of the top is D1 and the disc plate of the electrode plate. When the diameter of the portion is D2, it is preferable that D2> D1.

Further, in the electrode of the vacuum valve according to the fourth aspect of the present invention, the center of the back surface is joined to the tip of the current-carrying shaft, and a plurality of grooves are provided from the outside of the center to the bottom of the groove and the current-carrying shaft. An electrode plate with a plurality of protrusions formed on the outer circumference of the disk part is joined to the front surface of a bottomed cylindrical electrode that is formed radially in a direction orthogonal to the line connecting the axes, and this electrode It is characterized in that a disc-shaped contact is joined to the front surface of the plate.

[0024]

In the electrode of the vacuum valve thus constructed, the axial thickness of the coil portion of the electrode can be reduced, and the distance between the coil portions of the pair of electrodes opposed to each other inside the vacuum valve can be shortened. At the same time, the electric path of the coil portion is shortened.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the electrode of the vacuum valve of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view showing electrodes of a vacuum valve according to the first and second and third aspects of the invention, and FIG. 2 is a sectional view taken along line AA of FIG. In addition,
1 and 2 show the case of a movable electrode joined to a movable current-carrying shaft, and the fixed electrode also has the same structure by changing the movable current-carrying shaft to the fixed current-carrying shaft.

In FIGS. 1 and 2, on the upper surface of the vertical magnetic field electrode 1 brazed to the tip of the movable energizing shaft 17, projections 3b are provided on the disk-shaped outer periphery at intervals of 90 °. 3 is brazed, and a disc-shaped contact 2 is brazed to the upper surface of the electrode plate 3.

Of these, the longitudinal magnetic field electrode 1 is formed in a shallow U-shape in the longitudinal section shown in FIG. 2, and in the plan view of FIG. 1, it is the same as the electrode of FIG. 6 shown in the prior art. , 90 °
Arm portions 1a radially formed from the central portion at intervals and an arc-shaped coil portion 1 continuously formed at the tip of the arm portion 1a.
b.

Therefore, the difference from the electrode 21 shown in FIG. 6 is the same except that the tip 21c formed on the upper surface side of the tip of the coil portion 21b shown in FIG. 6 is omitted. That is, the upper surface of the coil portion 1b is a flat surface from the base portion to the tip.

The electrode plate 3 has a diameter D of the electrode plate 3.
The above-mentioned protrusion 3b protruding from the outer periphery of the disc portion 3a indicated by 1 is brazed on the front surface of the tip of the coil 1b. The dimension between the outer peripheral surfaces of the protrusions 3b opposite to each other at 180 ° (that is, the diameter of the circle connecting the tips of the protrusions 3b) is the same as the outer diameter of the vertical magnetic field electrode 1.

The contact 2 has a trapezoidal shape having a flat vertical cross section as shown in FIG. 2, and the outer diameter is a protrusion of the vertical magnetic field electrode 1 and the electrode plate 3 brazed to the upper surface of the vertical magnetic field electrode 1. It is the same as the distance between the parts 3b. An obtuse angle portion formed between a flat surface portion having a diameter D2 having substantially the same diameter as that of the movable energization shaft 17 which is an upper side of the trapezoidal contact 2 and a slope portion of the outer periphery is chamfered to prevent arc sticking. It is a curved surface.

Next, the operation of the electrodes of the vacuum valve thus constructed will be described. The current flowing from the movable energizing shaft 17 to the contact 2 flows from the longitudinal magnetic field electrode 1 connected to the tip of the movable energizing shaft 17 to the contact 2 through the electrode plate 3, and the surface of the contact 2 opposes the contact 2. Flows to the contact of the fixed side electrode that is provided.

Of these, the current flowing through the vertical magnetic field electrode 1 is
It flows from the arm portion 1a to the coil portion 1b. This coil part 1b
The electric current flowing through the coil portion 1b flows from the protrusion 3b of the electrode plate 3 brazed to the front surface of the tip of the coil portion 1b to the contact 2. Then, the current flowing through the coil portion 1b has an arc shape in the plan view of FIG. 1 and is in a direction orthogonal to the arc. Therefore, the magnetic flux generated by the current flowing through the coil portion 1b is generated between the pair of contacts at the time of interruption. A longitudinal magnetic field parallel to the arc is generated.

In the electrode of the vacuum circuit breaker thus constructed, the strength of the longitudinal magnetic field is changed to an optimum value corresponding to the breaking current by changing the number of coil portions 1b formed in the longitudinal magnetic field electrode 1. What can be done is as described above.

In the conventional vacuum valve electrode, when the axial thickness of the arm portion 1a and the coil portion 1b is increased in order to increase the current carrying capacity, the coil portion 1b incorporated in the fixed electrode is Coil part 1 incorporated in the movable electrode
Since the distance between b is increased, the strength of the longitudinal magnetic field with respect to the arc is reduced accordingly. However, in the electrode of the vacuum valve of the present invention, there is no projection in the axial direction due to the tip 21c shown in FIG. 6, and the distance between the coil portions 1b becomes closer to that much, so conversely increase the longitudinal magnetic field for the arc. You can

Therefore, by shortening the distance between the pair of electrodes facing each other, not only the length of the vacuum valve can be reduced but also the breaking performance can be improved. Further, by omitting the tip 21c, not only the shape of the electrode is simplified and the manufacturing is facilitated, but also the electric path of the coil portion is shortened, so that the resistance value of the coil portion is reduced, which causes the coil portion. It is possible to prevent temperature rise and increase current carrying capacity.

Further, since the contact 2 is brazed to the electrode plate 3 having the disk portion 3a having a large joint area with the diameter D1,
The joint strength can be increased, it can withstand impact at the time of injection, and the contact surface becomes small due to the bending of the contact surfaces to widen the mutual contact area, reducing the contact resistance, and reducing this contact resistance also reduces the temperature rise. Therefore, the current-carrying capacity can be increased.

Next, an embodiment of the electrode of the vacuum valve of the invention according to claim 4 is shown in FIG. 3 and a front view of FIG.
Described in. 3 and FIG. 4 are different from FIG. 1 and FIG. 2 in that a vertical magnetic field electrode 1A and a vertical magnetic field electrode 1A are provided.
The shape of the contact 2A brazed to the upper surface of the upper electrode plate 3 of FIG.

That is, in the longitudinal magnetic field electrode 1A, in FIG. 1, four grooves 1d are formed radially and symmetrically from a portion outside the center of the bottom. These grooves 1d are
It goes out to the outer periphery of the vertical magnetic field electrode 1A, and further, in the front view of FIG. Further, an acute-angled tip portion 1c1 is formed on the left side of this opening.

The electrode plate 3 to be brazed on the upper surface of the vertical magnetic field electrode 1A has a projection 3b projecting on the outer periphery of the electrode plate 3 and an upper surface of a tip 1c1 formed on the outer periphery of the vertical magnetic field electrode 1A. It is provided so as to overlap. On the other hand, in the contact point 2A, most of the contact surface is a flat surface, and a slightly curved surface portion is formed on the outer peripheral portion.

Even in the vacuum valve having the movable electrode and the fixed electrode as described above, the energizing current flows from the movable energizing shaft 17 through the longitudinal magnetic field electrode 1A to the contact portion 2A from the protrusion 3b of the electrode plate 3 and this process. In, the longitudinal magnetic field is generated by the groove 1d formed in the longitudinal magnetic field electrode 1A by the arc-shaped current flowing from the central portion of the longitudinal magnetic field electrode 1A to the tip portion 1c1 of the outer periphery.

In this case, compared with the electrodes shown in FIGS. 1 and 2, it is possible to increase the cross-sectional area of the arc-shaped electric path flowing from the movable energization shaft 17 to each tip 1c1 and the contact area between the contacts. Therefore, there is an advantage that the current carrying capacity can be further increased and the temperature rise of the electrode can be further reduced.

[0042]

As described above, according to the inventions of claims 1, 2 and 3, the central portion of the back surface is joined to the tip of the current-carrying shaft, and a plurality of current-carrying arm portions are radially formed from this central portion. Then, from the tip of this energizing arm portion, to the front surface of the electrode in which the coil portion is formed in an arc shape, the electrode plate having the plurality of protrusions formed on the outer circumference of the disc portion is joined, and the front surface of this electrode plate is joined. By connecting the disc-shaped contacts, the axial thickness of the electrodes was reduced, and the distance between the coil parts of the pair of electrodes opposite each other inside the vacuum valve was reduced. Thus, it is possible to obtain an electrode of a vacuum valve capable of increasing the current carrying capacity.

Further, according to the invention described in claim 4, the center portion of the back surface is joined to the tip of the current-carrying shaft, and a plurality of groove portions are provided from the outside of the center portion so as to form the bottom portion of the groove portion and the axis of the current-carrying shaft. To the front surface of the bottomed tubular electrode that is radially formed in a direction orthogonal to the line connecting the electrode plates, the electrode plate having a plurality of protrusions formed on the outer periphery of the disk part is joined, and By connecting a disc-shaped contact to the front surface, the axial thickness of the electrode was reduced, and the distance between the electric paths that generated a pair of longitudinal magnetic fields opposite each other inside the vacuum valve was reduced. Without, it is possible to obtain an electrode of a vacuum valve capable of increasing the breaking performance and the current carrying capacity.

[Brief description of drawings]

[0044]

FIG. 1 is a plan view showing an embodiment of electrodes of a vacuum valve of the invention according to claims 1, 2 and 3.

[0045]

FIG. 2 is a sectional view taken along line AA of FIG.

[0046]

FIG. 3 is a plan view showing an embodiment of an electrode of the vacuum valve according to the invention of claim 3;

[0047]

FIG. 4 is a front view of FIG.

[0048]

FIG. 5 is a vertical sectional view showing an example of a vacuum valve in which electrodes of a conventional vacuum valve are incorporated.

[0049]

FIG. 6 is a plan view showing a main part of an electrode of a conventional vacuum valve.

[0050]

[Explanation of symbols]

1, 1A ... Longitudinal magnetic field electrode, 1a ... Arm portion, 1b ... Coil portion,
1c, 1c1 ... Tip, 1d ... Groove, 2, 2A ... Contact point, 3
... electrode plate, 3a ... disk part, 3b ... projection part, 17 ... movable energizing shaft.

Claims (4)

[Claims] 1. The center of the back surface is joined to the tip of the current-carrying shaft,
A plurality of energizing arms are radially formed from this center part, and an electrode in which a coil part is formed in an arc shape from the tip of this energizing arm part, and a plurality of protrusions joined to the front surface of this electrode are the outer circumference of the disc part. An electrode of a vacuum valve, which is composed of an electrode plate formed on the substrate and a disc-shaped contact point joined to the front surface of the electrode plate. 2. The electrode of a vacuum valve according to claim 1, wherein the projection of the electrode plate is joined to the tip of the coil. 3. The cross-sectional shape of the contact is frustoconical in which the outer circumference of the top surface is a curved surface, the diameter of the top portion is D1, and the diameter of the disc portion of the electrode plate is D2, D2> D1. The electrode of the vacuum valve according to claim 1 or 2, characterized in that. 4. The center of the back surface is joined to the tip of the current-carrying shaft,
A plurality of groove portions are joined from the outside of the center portion to a bottomed cylindrical electrode radially formed in a direction orthogonal to a line connecting the bottom portion of the groove portion and the axis of the current-carrying shaft and the front surface of the electrode. An electrode of a vacuum valve, which is composed of an electrode plate having a plurality of protrusions formed on the outer periphery of the disc part and a disc-shaped contact point joined to the front surface of the electrode plate.