JP5020164B2 - Vacuum valve - Google Patents

Description

  The present invention relates to a vacuum valve provided with a windmill electrode, and more particularly to an improvement of the windmill electrode.

  For example, a technique as shown in FIG. 6 is disclosed as a conventional vacuum valve having a windmill electrode. FIG. 6A is an overall configuration showing a vacuum valve, and FIG. 6B is a perspective view of the movable electrode portion of FIG. A vacuum vessel 23 in which end plates 22a and 22b are attached to both ends of the insulating cylinder 21 and the inside thereof is in a high vacuum state is configured. In the vacuum vessel 23, a fixed electrode rod 24 penetrating one end plate 22a. The fixed electrode 25 fixed to the tip of the first electrode and the movable electrode 27 fixed to the tip of the movable electrode rod 26 penetrating the other end plate 22b are disposed to face each other. A bellows 28 is provided between the movable electrode rod 26 and the end plate 22b.

  The vacuum valve having such a configuration is configured to move the movable electrode rod 26 in the axial direction by using an operating device (not shown) connected to the movable electrode rod 26 as a drive source, thereby to Is electrically connected and separated. A shield 29 is attached to the inner wall of the insulating cylinder 21 in order to prevent metal vapor diffusing from the arc ignited between the electrodes 25 and 27 from adhering to the inner wall of the vacuum vessel 23.

As shown in FIG. 6B, the movable electrode 27 is formed in a windmill shape by providing a groove in the electrode itself. That is, a windmill part 31 located at the center and divided by the groove 30, and a plurality of contact parts 32 located at the periphery and divided by the groove 30 and thicker than the windmill part 31. It is joined to the movable electrode rod 26 at the center. The same applies to the fixed electrode 25.
With this configuration, the current path in the electrode is limited by the groove 30, and the magnetic field generated by the electric path causes a strong magnetic driving force to act on the arc immediately after the arc is generated, so that the arc is driven on the circumference of the electrode. Is moved to prevent arc stagnation and avoid local melting of the electrode, thereby improving the interruption performance (see, for example, Patent Document 1).

JP 2001-52576 A (page 4, FIG. 1)

The performance required for the vacuum valve includes short-circuit closing performance, short-time current withstanding performance, current-carrying performance (verified by a temperature rise test), and the like. As shown in the above-mentioned patent document 1, the type of the windmill-type electrode with the outer peripheral portion protruding is particularly excellent in short circuit interruption performance. However, there are the following problems of electromagnetic repulsion regarding short-circuiting performance and short-time withstand current performance. This will be described with reference to FIG. FIG. 7 is an electrode plan view of the electrode structure disclosed in Patent Document 1. As shown in FIG.
Usually, in the vicinity of the current peak of a short-circuit insertion test or a short-time withstand current test, a large current flows through almost one of the contact points between the fixed electrode and the movable electrode, so this contact point (hereinafter referred to as the energization point) A large electromagnetic repulsive force is generated at. However, in this electrode, there is a possibility that a conduction point is generated at a position as indicated by a circle in FIG. 7A. In this case, the current path A is formed between the fixed electrode surface and the movable electrode surface arranged opposite thereto. Are adjacent to each other and the direction of the current is opposite, so that an electromagnetic repulsive force is generated.

As a result of examining this electromagnetic repulsion force by experiment and magnetic field analysis, the following two points were found.
(1) The electromagnetic repulsive force generated between the fixed electrode and the movable electrode is equal to the sum of the electromagnetic repulsive force generated at the energization point and the electromagnetic repulsive force generated by the current path described above.
(2) The electromagnetic repulsive force generated by the current path between the fixed electrode surface and the movable electrode surface depends on the position of the energization point, and the energization point 41 close to the concave portion (windmill portion 31) of the electrode shown in FIG. The case of the energization point 42 on the tip side of the contact portion 32 is larger than the case. For this reason, the total electromagnetic repulsion force is 1.6 times greater in the case of the energization point 42 on the tip side than in the case of the energization point 41 close to the recess.
Since the position of energization varies, it is necessary to apply a large contact pressure so that the energization point 42 may be generated at the tip end side of the contact portion 32 in order to suppress arcing due to electromagnetic repulsion. As a result, the mechanical strength of the opening / closing mechanism has to be increased with the strengthening of the contact pressure spring, resulting in a problem that the circuit breaker becomes large.

  The present invention has been made to solve the above-described problems, and provides a vacuum valve provided with a windmill-type electrode that is excellent not only in short-circuit interruption performance but also in short-circuit insertion performance, short-time current resistance performance, and energization performance. The purpose is to do.

The vacuum valve according to the present invention is a vacuum valve having a pair of windmill-shaped electrodes that are detachably arranged in a vacuum vessel, wherein the windmill-shaped electrode includes a circular center portion joined to the electrode rod, The protrusion is divided into a plurality of circular arc portions by a plurality of grooves extending in a spiral shape from the center portion side toward the periphery of the protrusion portion. and which, hand of the one pair of the windmill type electrodes are widely formed toward the periphery of the width of the groove, the other wind turbine type length of the tip portion extending in the circumferential direction of the arcuate portion of the projecting portion The length is shorter than the tip of the electrode .

According to the vacuum valve of the present invention, the pair of windmill-shaped electrodes has a central portion and a protruding portion on the outer periphery thereof, and the protruding portion has a plurality of circular arcs by a plurality of grooves extending spirally from the central portion side toward the peripheral edge. part is divided into, windmill-shaped electrode of the hand is, since the wider toward the periphery of the width of the groove, the fixed electrode and the movable electrode is not in contact with the tip portion of the protruding portion, the electromagnetic repulsive force is suppressed Thus, while maintaining the short-circuit breaking performance, the short-circuiting performance and the short-time current withstanding performance can be enhanced. Therefore, the electrode diameter can be reduced and the contact pressure can be reduced, and as a result, the circuit breaker can be reduced in size.

Embodiment 1 FIG.
1 and 2 are plan views of wind turbine-shaped electrodes of a vacuum valve according to Embodiment 1 of the present invention. FIG. 1 and FIG. 2 are used by combining one as a fixed electrode and the other as a movable electrode. In the following description, FIG. 1 will be described as a fixed electrode and FIG. 2 as a movable electrode. FIG. 3 is a sectional view taken along line III-III in FIG. Further, since the overall configuration diagram of the vacuum valve is the same as that of FIG. 6 described in the background art section, illustration and description thereof are omitted.

In FIG. 1, a fixed electrode 1 that is a windmill-shaped electrode is made of a disk-shaped contact material, and surrounds a circular center portion 2 to which an electrode rod, which will be described later, is joined, and an outer periphery of the center portion 2. And a protruding portion 3 protruding toward the counter electrode from the surface. Then, a plurality of (four in the figure) grooves 4 extending in a spiral shape from the center 2 side toward the peripheral edge of the protrusion 3 are formed, and the protrusion 3 is formed by a plurality of (four) arc portions by the groove 4. It is divided into The groove 4 is cut from the front surface to the back surface of the electrode. The number of grooves 4 is not limited to four.
The surface shown in FIG. 1 is a surface facing the surface of the movable electrode 11 shown in FIG. 2 to be described later, and the protrusion 3 is in contact with the protrusion 13 of the movable electrode 11.

As shown in the side sectional view of FIG. 3, the fixed electrode 1 is provided with a joint hole 5 penetrating in the center, and the electrode rod 6 for guiding current from outside the vacuum vessel is narrowed into the joint hole 5. The tip is inserted and secured. A reinforcing plate 7 for supplementing mechanical strength is provided on the back surface of the fixed electrode 1, and a stainless steel spacer 8 is interposed between the shoulder portion of the electrode bar 6 and the reinforcing plate 7. It is fixed together by brazing.
The contact material of the fixed electrode 1 is preferably a Cu—Cr alloy containing 20 to 40% by weight of Cr or a Cu—Cr—Te alloy containing a small amount of Te. The reinforcing plate 7 is preferably SUS in terms of mechanical strength, withstand voltage performance, and conductivity.

Next, the movable electrode which is the other windmill type electrode will be described with reference to FIG.
The movable electrode 11 is basically the same as in FIG. 1, and includes a circular central portion 12 joined to the electrode rod 6 and a protruding portion 13 that surrounds the outer periphery of the central portion 12 and protrudes toward the counter electrode. In addition, a plurality of spiral grooves 14 are formed, but the shapes of the groove portions are different.
That is, the groove 14 has a shape in which the protruding portion 13 is divided into four arc portions by a plurality of (four in the drawing) grooves 14 extending spirally from the central portion 12 side toward the peripheral edge of the protruding portion 13. ing. Further, the width of the groove 14 is set to the peripheral edge of the protruding portion 13 so that the length of the tip portion (tip portion C) extending in the circumferential direction of the protruding portion 13 of the arc portion becomes shorter, that is, closer to the center portion 12. It is formed to become larger as it goes. The spiral direction of the groove 14 is opposite to the fixed electrode 1 when viewed from the contact surface side.

FIG. 4 shows a state in which the fixed electrode 1 and the movable electrode 11 are combined, and the shaded portion is a contact surface 15 where both electrodes come into contact when the electrode is closed. In addition, this contact surface is a design contact surface and is an area that can be contacted. In actuality, contact is made at some point (one point or a plurality of points) in this area.
By forming the shape of the groove 14 of the movable electrode 11 so as to become wider toward the peripheral edge, as shown in the figure, at the time of closing, all the protruding portions 3 and 13 of the fixed electrode 1 and the movable electrode 11 are all. Does not become a contact surface, and has a structure in which the tip portion (tip portion B) does not come into contact with the protruding portion 3 of the fixed electrode 1.

Next, the operation will be described with reference to FIG.
In the short-circuit insertion test and the short-time withstand current test, the contact surface 15 of both electrodes 1 and 11 is as shown in FIG. 4, but as described above, at the current peak, almost one point anywhere on the contact surface. A large current is applied. The total electromagnetic repulsive force is 1.6 times greater when the energization point is closer to the tip side (tip B) than the center of the electrode.
Therefore, in the present embodiment, as shown in FIG. 4, the structure is configured such that the tip end portion B of the projecting portion does not come into contact, so that the electromagnetic repulsion force is suppressed as compared with the conventional windmill electrode.

In the short circuit interruption test, the electrode pairs 1 and 11 are dissociated and an arc is generated on the contact surface 15. FIG. 4 shows the arc occurrence locations with circles. The arc is generated at an arbitrary position as long as it is on the contact surface 15, and FIG. 4 shows, for example, 16a to 16c as an example. The current I flowing through the electrode rod 6 flows from the joint portion of the joint hole 5 into the electrode 1 (or 11), and flows through the center portion 2 (or 12) corresponding to the contact surface 15 where the arc 16a is generated. The projection 16) flows into the arc 16a. In FIG. 4, the current I ₂ is shown. The arc 16a receives the driving force F in the circumferential direction by the circumferential component I ₂ θ of the current I ₂ . For this reason, the arc receives a strong magnetic driving force immediately after the arc is generated. As a result, for example, the arc 16a moves at a high speed toward the position of the arc 16b, and further moves to the adjacent protrusion through 16c. This operation is carried out continuously, and in effect during the generation of the arc, it rotates on the protrusion. As a result, since the arc moves at a high speed immediately after the arc is generated, the temperature of the contact surface is suppressed, and the generation of metal vapor is also suppressed, so that the same breaking performance as that of the conventional windmill electrode is obtained.

In order to improve the energization performance and suppress the temperature rise of the vacuum valve, it is necessary to keep the contact resistance of the contact surface between the fixed electrode and the movable electrode low. In the present embodiment, the contact area at the tip of the protrusion is reduced, but in order to compensate for this, it can be dealt with by reducing the inner diameter of the protrusion.
Further, when the rated voltage is not high, it is also possible to increase the contact area by reducing the chamfer R (see FIG. 5) of the protruding portion end. In this case, the rating can be raised by increasing the applied voltage or applying current conditioning in the conditioning of the vacuum valve.

  In the above description, the electrode having the shape shown in FIG. 2 is a movable electrode. However, the electrode shown in FIG. 2 may be a fixed electrode, and the electrode shown in FIG. good.

  As described above, according to the vacuum valve of the present invention, in the vacuum valve having a pair of windmill-shaped electrodes that are detachably arranged in the vacuum vessel, the windmill-shaped electrode has a circular center joined to the electrode rod. And a plurality of protrusions formed by a plurality of grooves extending spirally from the center side toward the peripheral edge of the protrusion. And at least one of the pair of windmill-shaped electrodes is formed so that the width of the groove increases toward the periphery, and the length of the tip portion extending in the circumferential direction of the arc portion of the protruding portion Therefore, the fixed electrode and the movable electrode are not in contact at the tip of the projecting part, the electromagnetic repulsion force is suppressed, and the short-circuit closing performance and short-time current resistance performance are maintained while maintaining the short-circuit breaking performance. Can be increased. Therefore, the electrode diameter can be reduced and the contact pressure can be reduced, and as a result, the circuit breaker can be reduced in size.

Embodiment 2. FIG.
FIG. 5 is a sectional view showing a windmill electrode portion of a vacuum valve according to Embodiment 2 of the present invention. Since the planar structure of the electrodes other than those shown is the same as that of the first embodiment, the illustration and description are omitted. The overall configuration of the vacuum valve is the same as that shown in FIG.

,
As a result of the examination by the experiment and the magnetic field analysis, it has been found that there is a method of increasing the height of the protruding portion as another method for reducing the electromagnetic repulsion force in the short-circuit insertion test and the short-time current resistance test. Therefore, in this embodiment, the dimensional relationship of the electrodes is as follows.

In FIG. 5, h is a protruding height protruding from the surface of the central portion 12 toward the counter electrode side of the protruding portion 13, k is a thickness of the central portion 12, and H is a total thickness of the protruding portion 13.
Then, h = 4 mm to 8 mm, k = 3 mm to 7 mm, and H = 15 mm or less.
In addition, as a vacuum valve to which the electrode of the said dimension is applied, the thing with a rated current of about 20 kA-40 kA is assumed.
In the above dimensions, it was verified by experiments and magnetic field analysis that the electromagnetic repulsion force can be reduced particularly when the projection height h is in the above range. For example, when the protrusion height is increased from 3 mm to 5 mm, the electromagnetic repulsion force decreases by about 10%. If the protrusion height is increased, the magnetic driving force related to the breaking performance will be reduced, and the breaking performance will be slightly reduced. Reduction of contact pressure can be achieved.
This dimension can be applied to both the fixed electrode and the movable electrode.

  As described above, according to the vacuum valve of the second embodiment, the projecting height of the projecting part projecting from the center surface to the counter electrode side is set to 4 mm or more and 8 mm or less. Since the performance and short-time withstand current performance can be balanced, the electrode diameter can be reduced and the contact pressure can be reduced. As a result, the circuit breaker can be reduced in size.

It is a plane which shows one electrode of the windmill type electrode of the vacuum valve by Embodiment 1 of this invention. It is a plane which shows the other windmill type electrode which becomes a pair with FIG. FIG. 3 is a sectional view taken along line III-III in FIG. 1. It is a figure explaining operation | movement of the windmill-shaped electrode of the vacuum valve by Embodiment 1 of this invention. It is sectional drawing which shows the windmill type electrode of the vacuum valve by Embodiment 2 of this invention. It is sectional drawing and the principal part enlarged view which show the conventional vacuum valve. It is a figure explaining operation | movement of the vacuum valve of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fixed electrode (windmill-shaped electrode) 2 Center part 3 Projection part 4 Groove 5 Joint hole 6 Electrode rod 7 Reinforcement plate 8 Spacer 11 Movable electrode (windmill-shaped electrode) 12 Center part 13 Projection part 14 Groove 15 Contact surface 16a-16c Arc .

Claims (2)

In a vacuum valve having a pair of windmill-shaped electrodes arranged in a vacuum container so as to be able to contact and separate,
The windmill-shaped electrode has a circular center part joined to the electrode rod, and a projecting part which is on the outer periphery of the center part and protrudes from the surface of the center part toward the counter electrode, from the center part side The protrusion is divided into a plurality of arc portions by a plurality of grooves extending spirally toward the periphery of the protrusion,
Hand of said pair of the windmill type electrodes are widely formed toward the width of the groove in the periphery, the length of the distal end portion extending in a circumferential direction of the arcuate portion of the projecting portion and the other A vacuum valve characterized by being shorter than the tip of the windmill electrode .   2. The vacuum valve according to claim 1, wherein a protruding height of the protruding portion protruding from the surface of the central portion toward the counter electrode is 4 mm or more and 8 mm or less.

Images