JPH0243063Y2 - - Google Patents

Description

[Detailed Description of the Invention] A. Field of Industrial Application The present invention relates to a vacuum interlayer having a coil behind one electrode and a relaxation shield for mitigating an electric field behind the other electrode.

B. Overview of the device This device includes a coil behind one electrode, a relaxation shield behind the other electrode that surrounds the inner end of the other lead rod to alleviate electric field concentration, and a metal In a vacuum interrupter in which a member surrounds an electrode, a relaxation shield is formed in a substantially truncated conical shape extending from the outer peripheral surface of the other lead rod to the outer peripheral surface of the other electrode, and is continuous with the opposite electrode side of the relaxation shield. By covering at least the portion of the outer circumferential surface of the other lead rod corresponding to the metal member with a material having a high withstand voltage, the brazing material when brazing the relaxation shield to the other lead rod is This prevents leakage from the outer peripheral surface and deterioration of withstand voltage characteristics.

C. PRIOR TECHNOLOGY There is a vertical magnetic field application type vacuum interintervalter that applies a magnetic field parallel to the arc generated between both electrodes in order to improve the shearing performance.

There are various methods for applying a longitudinal magnetic field, but there is one that improves shearing performance and reduces size by providing a magnetic field generating coil only behind one electrode.

FIG. 3 shows a cross-sectional view of a vacuum interlocker with a coil behind one of the electrodes and outside the vacuum vessel. As shown in the figure, a vacuum container 4 is connected to an insulating cylinder 1 made of ceramic or the like and metal end plates 2, 3, etc.
A fixed lead rod 6 and a movable lead rod 7 that can approach and separate from each other inside the vacuum container 4 are constructed.
has been introduced. A fixed electrode 8 and a movable electrode 9 are fixed to the inner ends of the fixed lead rod 6 and the movable lead rod 7. 10 is a coil provided outside the vacuum vessel 4 behind the fixed electrode 8 which is one electrode, 11 is a shield as a metal member having the same potential as the fixed electrode 8, 12 is a bellows, and 13 is a bellows shield. be. Behind the movable electrode 9, which is the other electrode, there is a relaxation shield 5, which is shaped like a disk and has a curved outer circumferential portion, connected to a movable lead rod 7 in order to prevent electric field concentration near the outer circumferential surface of the electrode and improve withstand voltage characteristics. It is fixed by brazing.

According to such a vacuum interrupter, the coil 10
Because the vertical magnetic field is applied, the shear cutting performance is high.
Moreover, the electric field concentration near the outer peripheral surface of the movable electrode 9 is alleviated by the relaxation shield 5, so that the withstand voltage characteristics are also good.

In this way, when a coil is provided only behind one electrode, the electrode on the side having the coil can be provided close to the metal end plate, contributing to miniaturization. However, since most of the vacuum container is formed on the other electrode side, the other electrode side must have a structure that is harsh in terms of electric field, and further improvements in shearing performance and withstand voltage characteristics are difficult to achieve. It was not what I expected. That is, since the distance between the relaxation shield 5 and the shield 11 is structurally narrow, electric field concentration tends to occur in this portion. Moreover, since the surfaces of the shield 11 and relaxation shield 5, especially the surfaces of the curved portions, are in an amorphous state of Fe ₂ O ₃ , electrons are easily emitted, and the curved portions face each other with a short vacuum gap. This causes a decrease in withstand voltage.

In other words, although the various shields are made of SuS material, which has high voltage resistance characteristics, it is formed by bending certain parts by pressing or squeezing, so the heat generated during this plastic deformation It is known that the surface of the member is in an amorphous state of Fe ₂ O ₃ (Japanese Patent Publication No. 58-55609). This Fe ₂ O ₃ is characterized by a large secondary electron emission coefficient.

Therefore, it has been found that problems with the structure and surface condition are combined to cause a significant drop in withstand voltage.

As a means to solve the above drawbacks, the fourth
As shown in Figure a, the relaxation shield 14 has a substantially truncated conical shape.
It is possible to install a That is, a shield is provided so as to connect the outer periphery of the movable electrode 9 and the movable lead rod 7 with a straight surface, so that the curved portions of the shield 11 and the relaxation shield 14 face each other with a short vacuum gap. It is important to configure the system so that it is not necessary to do so.

In such a vacuum interlude, the gap between the curved portions of the shield 11 and the relaxation shield 14 can be made larger, so that the withstand voltage characteristics can be improved more than the above-mentioned vacuum interlude. It should be noted that the vacuum interlude shown in FIG. 4a is the same as that shown in FIG. 3 except for the relaxation shield.

D Problems to be solved by the invention However, the mitigation shield 14 is
The following new problems arose due to the use of brazing to fix the parts. That is, A in FIG. 4a
As shown in FIG. 4b, an enlarged view of the brazing filler metal 19
is placed inside the relaxation shield 14 to prevent the brazing material from flowing out onto the outer surface of the movable lead rod 7 when it melts, but in reality, the brazing material flows onto the outer surface of the movable lead rod 7. . This is thought to be caused by the following.

A gap exists between the outer periphery of the small diameter portion 7a and the inner diameter of the relaxation shield 14, and when the relaxation shield 14 is attached, the gap is shifted and the brazing material flows out from the side with the larger gap.

Since the relaxation shield 14 is simply placed on the large diameter portion 7b, the relaxation shield 14 is lifted by the melted brazing material, and the brazing material flows out onto the outer surface of the movable lead rod 7.

On the other hand, looking at the electric field distribution, because the movable electrode 9 and the movable lead rod 7 are connected smoothly and linearly by the relaxation shield 14 due to the structure, the electric field is distributed between the movable electrode 9, the movable lead rod 7, and the relaxation shield. 14, and the seeped brazing filler metal 15 is exposed to a strong electric field. As described above, a. The brazing metal seeps out from the outer peripheral surface of the movable lead rod 7.

b. The brazing filler metal 15 seeping out from the outer peripheral surface of the movable lead rod 7 is exposed to a strong electric field.

It was found that the withstand voltage characteristics deteriorated due to this.

Therefore, an object of the present invention is to provide a vacuum interrupter that solves the problem of such a gap.

E Means for solving the problem The structure of the present invention to achieve this purpose is as follows:
A pair of lead rods that can approach and separate from each other are introduced into the vacuum chamber, and an electrode is fixed to the inner end of each lead rod. In a vacuum interoperator which is provided with a coil behind the other electrode and a relaxation shield surrounding the inner end of the other lead rod, the relaxation shield is connected from the outer peripheral surface of the other lead rod to the other electrode. It is formed into a substantially truncated conical shape extending to the outer peripheral surface, and is continuous with the opposite electrode side of the relaxation shield, and at least a portion of the outer peripheral surface of the other lead rod corresponding to the metal member is covered with a material having a high withstand voltage. It is characterized by

F Effect Since at least the part of the other lead rod that corresponds to the metal member is covered with a material with high withstand voltage,
Even if the brazing material flows down when the mitigation shield is brazed to the other lead rod, it will flow between the lead rod and the component with high withstand voltage, and the brazing material will not directly oppose the metal component. do not have. Therefore, the withstand voltage characteristics do not deteriorate due to the brazing filler metal.

G. Embodiments Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings. It should be noted that this example is a partial improvement of the conventional vacuum interrupter mentioned above.
Identical parts will be given the same reference numerals and explanations will be omitted, and only different parts will be explained.

What is shown in FIG. 1a is a movable lead rod in the vacuum interlocker of Example 1. The movable lead bar 7 is composed of a small diameter part 7a and a large diameter part 7b on the inner end side, and surrounds the inner end of the movable lead bar 7 and extends from the outer peripheral surface of the movable lead bar 7 to the movable electrode 9. A substantially truncated cone-shaped relaxation shield 14 extending to the vicinity of the outer peripheral surface is inserted into the small diameter portion 7a and brazed. The relaxation shield 14 has an acute angle θ from the electrode fixed side of the movable lead rod 7, and is bent inward near the outer peripheral surface of the movable electrode 9 to form a curled portion 14a. A stainless steel pipe 16 is covered and brazed to a portion of the outer circumferential surface of the movable lead rod 7 below the relaxation shield 14 in the figure as a member with high withstand voltage characteristics. A notch 16a is formed along the circumference of the inner periphery of the upper end of the stainless steel pipe 16 in order to store the brazing material seeped out during brazing (see FIG. 1b).
A groove 16b for accommodating a wire brazing material for brazing the stainless steel pipe 16 to the movable lead rod 7 is formed along the circumferential direction on the lower inner peripheral surface. 1st
In FIG. b, 19 is a wire brazing material arranged for brazing the relaxation shield 14 and the stainless steel pipe 16.

What is shown in FIG. 2 is a movable lead rod in the vacuum interlocker of Example 2. Movable lead rod 17
is covered with a shield pipe 18 that integrates a relaxation shield and a stainless steel pipe, and is brazed to the shield pipe 18. To braze the shield pipe 18, a wire brazing material 19 may be interposed between the relaxation shield portion and the movable lead rod 17 and heated as shown in FIG.

In both Examples 1 and 2, the entire area below the relaxation shield on the outer peripheral surface of the movable lead rod is covered with stainless steel material, but it is sufficient to cover at least the portion corresponding to the shield 11 as a metal member. That is, it is sufficient to cover the portion indicated by L in FIG. 1a and FIG. 2. Here, metal members include metal tubes or shields that have the same potential as one electrode,
Alternatively, it refers to a metal tube or intermediate shield at an intermediate potential.

Next, the operation of such a vacuum interrupter will be explained. As shown in Figure 1b, each member and wire brazing material 1
9 is placed and then heated and brazed, the upper brazing material 19 melts and joins the relaxation shield 14 and the movable lead rod 7. In the unlikely event that wax oozes out, the wax will accumulate in the notch 16a or flow into between the stainless steel pipe 16 and the movable lead rod 7. On the other hand, the brazing material 19 contained in the groove 16b flows between the stainless steel pipe 16 and the movable lead rod 7, and both are brazed to each other. Therefore, the brazing material will not seep out to the outside of the stainless steel pipe 16 to form a convex portion, and the withstand voltage characteristics will not deteriorate. Additionally, in general, the electric field strength of a vacuum interrupter tends to be larger on the center side (movable lead rod side) than on the outside, and if there is a copper member with poor voltage resistance characteristics in the center, this may cause Although this could sometimes be a cause of a decrease in the withstand voltage characteristics, by covering the outer circumferential surface of the movable lead rod 7 with the stainless steel pipe 16 having a high withstand voltage characteristic, an improvement in the withstand voltage characteristics can be expected from this point as well. The case in FIG. 2 is similar to the case in FIG. 1, so the explanation will be omitted.

In this embodiment, a case has been described in which a coil is provided behind a fixed electrode, but a coil may be provided behind a movable electrode. Further, the place behind the electrode where the coil is provided may be not only the outside but also the inside of the vacuum container.

H. Effect of the invention As explained above, according to the invention, a relaxation shield is provided behind the electrode on the side that does not have a coil,
Since the part of the lead rod that is continuous with the relaxation shield and corresponds to at least the metal member is covered with a material having a high withstand voltage, the brazing material is applied to the outer peripheral surface of the lead rod at the back of the electrode at the point of electric field relaxation at the back of the electrode. The combination of the fact that no seepage is formed and the fact that the outer circumferential surface of the lead rod is made of a material with high withstand voltage can improve the withstand voltage characteristics.

[Brief explanation of the drawing]

Figures 1a, b, and 2 relate to an embodiment of the vacuum interrupter according to the present invention, where Figure 1a is a configuration diagram showing the vicinity of the movable lead rod of Example 1, and Figure 1b is Figure 1a. FIG. 2 is a configuration diagram showing the vicinity of the movable lead rod of Embodiment 2, FIG. 3, FIG. 4 a,
b relates to a conventional vacuum interrupter, FIGS. 3 and 4 a are cross-sectional views, and FIG. 4 b is A in FIG. 4 a.
FIG. 4...Vacuum container, 6...Fixed lead rod, 7,1
7...Movable lead rod, 8...Fixed electrode, 9...Movable electrode, 10...Coil, 11...Shield,
5, 14... Relaxation shield, 16... Stainless steel pipe, 18... Shield pipe.

Claims (1)

[Scope of utility model registration request] A pair of lead rods that can approach and separate from each other are introduced into the vacuum chamber, and an electrode is fixed to the inner end of each lead rod. In a vacuum interrupter having a coil behind the other electrode and a relaxation shield surrounding the inner end of the other lead rod, the relaxation shield is connected from the outer peripheral surface of the other lead rod to the other electrode. It is formed into a substantially truncated conical shape extending to the outer peripheral surface, and is continuous with the opposite electrode side of the relaxation shield, and at least a portion of the outer peripheral surface of the other lead rod corresponding to the metal member is covered with a material having a high withstand voltage. A vacuum interrupter characterized by: