JPS6351335B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vacuum shield breaker which is an improved electrode that generates an axial magnetic field by itself.

Conventionally, various improvements have been made to the electrode structure of vacuum shield disconnectors in order to obtain good large current disconnection performance. Recently, an electrode structure has been proposed in which the electrode itself generates an axial magnetic field, that is, a magnetic field oriented parallel to the arc, thereby uniformly distributing the arc over the electrode surface and preventing local overheating of the electrode.

The conventional arc electrode itself is a single piece of electrode.
The electrode that generates the axial magnetic field is configured as follows.

A pair of electrodes, which are arranged correspondingly in the vacuum container and can be moved toward and away from each other, are provided with conductive rods on the back surface, and these extend outside the vacuum container. A pair of through grooves are formed on the corresponding surfaces of the electrodes, and a current conducting part is formed between the through grooves. The through groove and current conducting portion of one electrode are arranged to be orthogonal to the through groove and current conducting portion of the other electrode.

Now, when one electrode is separated from the other,
An arc is generated between both electrodes. The arc current is
It flows from the center of one electrode along the current-carrying part in the radial direction, splits in the circumferential direction at the place where the through groove is cut, reaches the arc on the arc ignition parts on both sides, and flows into the other electrode. The other electrode follows the opposite path to that described above. Therefore, the radial current flowing in the current-carrying part and the circumferential current flowing in the ignition part generate an axial magnetic field in the space between the electrodes, and this magnetic field uniformly disperses the arc on the electrode surface, resulting in a good It is possible to obtain excellent breaking performance.

By the way, in the conventional electrode structure, if the surface electrodes are in uniform contact, immediately after the two electrodes are separated,
The arc is generated uniformly on the electrode surface, and the axial magnetic field as described above is generated throughout the interelectrode space, causing no problem. However, in general, it is rare for both electrodes to be in uniform contact, and it is common for them to be in contact at one or several locations. In this case, the arc generated immediately after opening is also concentrated in one or several locations. If the arc is concentrated in one place, for example at the center of the electrode, the arc current will be
Since there is no flow in either the radial current-carrying part or the circumferential firing part, no axial magnetic field is generated. Further, when the arc is shifted from the center of the electrode, for example, when it is concentrated at one point in the ignition part, an axial magnetic field is unlikely to be generated in the entire inter-electrode space. In this way, if the arc concentrates in one place immediately after the electrodes are separated, a sufficient axial magnetic field will not be generated and the shearing performance will deteriorate. On the other hand, even if the arc is once dispersed on the electrode surface, it will concentrate on a part of the electrode due to the influence of the electromagnetic force of the large current flowing in the circuit outside the circuit breaker and the instability of the arc itself. There are cases.
In such a case, the generated axial magnetic field is insufficient, and good cutting performance cannot be obtained.

An object of the present invention is to provide a vacuum shear breaker that generates an axial magnetic field over the entire electrode and has improved shearing performance.

The electrode of the present invention is provided with a bridging conductor that straddles at least one pair of through grooves formed on a corresponding surface and a current-carrying part formed between the through grooves and connects between the firing parts formed on the outside of the through grooves. The arc current flows in a loop over the entire area of the corresponding surface, generating an axial magnetic field over the entire surface of the electrode, and improving shearing performance.

The axial magnetic field generating section 30 of the present invention will be explained below with reference to the embodiment shown in FIG. The axial magnetic field generating section 30 is configured as follows. A pair of electrodes 2A and 2B, which have conductive rods 1A and 1B extending outside the vacuum container attached to their back surfaces and can be freely connected and separated, are arranged correspondingly inside the vacuum container. For example, the conductive rod 1A and the electrode 2A are the small diameter part of the tip of the conductive rod 1A and the electrode 2.
The central part of the rectangle surrounded by the penetrating rod 4 is butted against and brazed. Other conductive rod 1
The bonding between B and the electrode 2B is also exactly the same as described above.
One electrode 2A has a corresponding surface 3 with the other electrode 2B.
A pair of parallel through grooves 4 extending substantially in the radial direction.
is formed. Therefore, the current-carrying portion 6 is provided between the through grooves. The through groove 4 and the current conducting part 6 on one side and the through groove 5 and the current conducting part 7 on the other side are orthogonal to each other. There are through grooves 4 on the left and right sides of the current-carrying part.
A semicircular arc ignition part 8 is formed through the through groove, and is connected to the current-carrying part 6 at the end of the through groove. The hole 10 in the center of the electrode extends from the center O to the through groove 4 and the ignition part 8.
It spans part of the ridge, forming a circular depression. A bridging conductor 11 shown in FIG. 1C is provided in this recess 10 so as to be in contact with both the ignition parts 8 and not in contact with the through groove 4 or the current carrying part 6.

The bridging conductor 11 is connected to both the ignition parts 8 via the connecting part 8A at the arcuate end part 11A and the bottom part. A part of the hole 10 is formed between the parallel end portion 11B in the right angle direction of the connecting portion 8A and the inner surface of the firing portion.
A gap is formed between the current-carrying portion 6 and the bridging conductor 11 corresponding to the hole. The side surface of the current-carrying portion 6 opposite to the gap 12 is connected to the conductive rods 1A and 1B.

The pair of electrodes 2A, 2B is provided with a reinforcing plate 13 on the back side, and the above-mentioned conductive rod 1A,
1B is installed. This reinforcing plate 13 is made of a high resistivity material such as stainless steel.

Next, the state of the arc, the trajectory of the current, and the state of the generated magnetic field when one electrode 2A is separated from the other electrode 2B will be explained with reference to FIG.

(1) When the arc 20 is ignited at the center of the electrode, that is, on the bridging conductor, the arc current I flowing from the conductive rod 1A is divided at the center of the conductive rod 1A, as shown by the arrow, and energized. Flows to points A and B on the ignition section, and at points A and B, it branches to the ignition section 8, flows in the circumferential direction, reaches the bridging conductor from points C and D on the ignition section, and joins, It flows to the other electrode 2B. At the other electrode 2B, a similar current loop is formed by following the opposite path to that described above. Therefore, when the current locus is projected in the axial direction, it becomes as shown in Figure C, where a fan-shaped loop current flows uniformly, and each fan-shaped area has an axial magnetic field H ₁ of the same strength. , H ₂ , H ₃ , and H ₄ are generated.

(2) The arc 20 is connected to the ignition part 8 as shown in FIG.
When a portion of the electrode is ignited, the arc current is still formed in a loop over the entire electrode. In this case, the direction of the current in one electrode 2A and the current in the other electrode 2B are partially reversed, and they appear to cancel each other out, but the longer the current path, the greater its impedance and the smaller the current. To,
Overall, as shown in Figure C, four fan-shaped currents flow almost uniformly, and each region,
, , an axial magnetic field of comparable strength is obtained. In fact, when we simulate the case where the arc is concentrated in a part of the ignition part and measure the distribution of the strength of the axial magnetic field, we find that the axial magnetic field is distributed over the entire electrode, as shown in Figure D. There is.

On the other hand, an electrode in which the bridging conductor 11 is not used in FIG. 1 will be explained with reference to FIG. 3.

(1) When the arc 20 is ignited at the center O of the electrodes as shown in Fig. 3A, the current trajectory connects the conductive rod 1A of one electrode to the conductive rod 1B of the other electrode, as shown by the arrow. The path connects in a straight line, and no axial magnetic field is generated.

(2) As shown in Figure 3B, when the arc 20 is concentrated in a part of the semicircular ignition part, the current flows only in half of one electrode, so
When the current trajectory is projected in the axial direction, a biased current loop is created as shown in C in the figure. Therefore,
Since the magnetic field strength distribution becomes non-uniform as shown in Figure D, the arc is difficult to disperse and the shearing performance is inhibited.

In this way, in the present invention, even if the arc is biased towards the center of the electrode or a part of the arc ignition part, an axial magnetic field is generated in the entire space between the electrodes, the biased arc is quickly dispersed, and the arc is not affected properly. It is possible to obtain cutting performance. Furthermore, since it has become possible to generate an axial magnetic field with only one electrode, for example 2A, the vacuum shield and disconnector can be made smaller.

FIG. 4A shows another embodiment of the present invention,
The difference from FIG. 1 is that the bridging conductor 11 is configured to be convex with respect to the ignition part 8, so that when a pair of electrodes are in contact, the bridging conductor 11 is always in contact. . In this embodiment, an arc is always generated on this bridging conductor 11 immediately after the electrodes are opened, so a balanced axial magnetic field is generated from the beginning of the opening, and the arc is uniformly dispersed. Can be done.

FIG. 4B shows still another embodiment, in which the through groove 4 is extended in the circumferential direction to the ignition part 8. In this embodiment, the current flowing through the ignition part 8 is detoured as close to the outer circumference as possible, which has the effect of widening the magnetic field generation area and dispersing the arc over a wider range.

FIG. 4C shows still another embodiment, in which one electrode is provided with three radial current-carrying parts 6. In this example, by rotating the electrodes of the same structure by 60 degrees around the axis and arranging them correspondingly, six current loops are created as shown in Figure 4D, and the entire interelectrode space is axially A magnetic field can be generated.

Note that the same effect can be obtained by fitting a current blocking portion such as a high resistivity member such as stainless steel or an insulator into the through groove described above.

As described above, according to the present invention, even if the arc is biased towards the center of the electrode or a part of the ignition part, an axial magnetic field is generated in the entire space between the electrodes, so the arc can be quickly dispersed over the entire electrode. , good cutting performance can be obtained. Furthermore, since an axial magnetic field can be generated with only one electrode, the vacuum shield and disconnector can be made smaller.

[Brief explanation of the drawing]

FIG. 1 is a diagram of an electrode of a vacuum shield breaker shown as an embodiment of the present invention, where A is a perspective view and B is a perspective view.
XX sectional view of Figure A, Figure C is a perspective view of the bridging conductor, Figure 2 A, B, and C are diagrams explaining the current trajectory in Figure 1, Figure D is a diagram explaining the magnetic field distribution, Figures 3A, B, and C are diagrams for explaining current trajectories of conventional electrodes, Figure D is a diagram for explaining magnetic field distribution, and Figure 4 is an electrode shown as another embodiment of the present invention. A is a cross-sectional view, B and C are plan views, and D is a diagram for explaining the current locus of C in the same figure. 1... Conductive rod, 2... Electrode, 3... Corresponding surface,
4, 5... Through groove, 6, 7... Current carrying part, 8, 9...
...Ignition part, 11...Bridging conductor, 20...Arc.

Claims (1)

[Claims] 1 A pair of electrodes that can be freely moved toward and away from each other and have a conductive rod on the back side are arranged correspondingly in a vacuum container, and the electrodes are provided with an axial magnetic field generating section that generates an axial magnetic field, wherein the axial magnetic field generating section In this method, a hole is provided in the electrode facing the conductive rod, at least two or more through grooves that do not reach the outer periphery from the hole are provided in the hole, and at least four or more are provided, and a current-carrying part is formed between the pair of through grooves. Then, a bridging conductor provided perpendicularly to the through groove is connected to the inner surface of the hole, a gap is formed between the bridging conductor corresponding to the hole and the current carrying part, and a conductive rod is connected to the electrode in the passage part. A vacuum shield disconnector characterized in that the pair of electrodes are arranged in correspondence with each other so that the through groove of one side electrode and the through groove of the other side electrode are orthogonal to each other.