JPS64776B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vacuum interrupter, and more particularly to a vacuum interrupter equipped with a coil electrode that generates a magnetic field parallel to an arc when the arc is interrupted.

The vacuum interrupter 1 is generally constructed as shown in FIG. That is, a cylinder 1 made of an insulator
1, 11, metal end plates 12, 13 and bellows 14
An electrode (fixed electrode) 2 is attached to the inner end of a lead rod 15 which is fixedly fixed through the end plate 12 in an airtight manner. Lead rod 1 that can be moved freely
An electrode (movable electrode) 3 is provided at the inner end of the electrode 6 . 17 is a main shield made of metal such as non-magnetic stainless steel, and a pair of electrodes 2, 3,
The lead rods 15 and 16 are arranged so as to partially surround the lead rods 15 and 16 to prevent metal vapor scattered from the pair of electrodes 2 and 3 from adhering to the inner surface of the cylinder 11 made of an insulating material.

By moving up and down in the figure, one electrode 3 comes into contact with and separates from the other electrode 2, thereby making or breaking the electrical circuit.

Note that the vacuum interrupter 1 is not limited to the configuration shown in FIG. Some are made of an insulating material, and some are made so that the fixed lead rod 15 can also be moved via a bellows.

Next, the configurations of the electrodes 2 and 3 will be described. Since both the electrodes 2 and 3 have similar configurations, the following explanation will be based on the electrode 3 and will be explained based on FIGS. 2 to 4.

Reference numeral 31 denotes an arc electrode that comes into contact with the opposite mating electrode 2, and this electrode 31 is integrated with the circular root 32a of the coil electrode 32 via a non-magnetic (for example, stainless steel, Inconel) high-resistance material 33. are connected to each other. This coil electrode 32 is for generating a magnetic field parallel to the arc generated between the opposing electrodes 2 and 3, and has a circular root 32a connected to the lead rod 16 as shown in FIG.
and a plurality of (two) arms 32b extending radially outward from this root 32a, one end of which is connected to the outer end of each arm 32b, and the other end of which is connected to the other arm 32b via a gap 32d. It is formed of a plurality (two) of circular arc portions 32c facing each other, and constitutes a so-called 1/2 branch (1/2 turn) coil electrode.

Further, the tip of the arc portion 32c of the coil electrode 32 in the arc direction is connected to the back of the arc electrode 31 via a connecting conductor 34.

Reference numeral 4 denotes a reinforcing member made of a non-magnetic and high-resistance material (for example, stainless steel or Inconel), which is a reinforcing member for the coil electrode 32 fixed to the tip of the lead rod 16, and is fixed to surround the lead rod 16. ing. As shown in FIG. 4, this reinforcing body 4 includes circular arc members 43 provided in the same number (2 pieces) as the circular arc parts 32c of the coil electrode 32, and these circular arc members 43 are connected to ring-shaped bosses 41, respectively. A plurality of radially connected arms 42a, 42
b, 42c, and 42d.
The two arcuate members 43 are each separated by a gap 44 located in the radial direction, and a space 45 is formed between each arm.

Reference numeral 5 denotes an auxiliary shield made of, for example, non-magnetic stainless steel, located on the back of the reinforcing body 4;
This auxiliary shield 5 is attached to the lead rod 16 via a fitting 51.

The lead rod 16 is a lead pipe 16 made of copper.
a, a shaft rod 16b made of a non-magnetic material (for example, stainless steel or Inconel), and an auxiliary member 16c made of a non-magnetic material that connects both members.

By the way, as mentioned above, the electrode 3 (and 2) equipped with the coil electrode 32 that generates a magnetic field parallel to the arc has the coil electrode 32 provided with the air gap 32d between each circular arc portion 32c, and the coil electrode 32 and Due to the presence of the connecting conductor 34 that connects the arc electrode 31, the shape of the outer peripheral side surface portion of the electrode (the portion facing the main shield 17) is extremely complex.

Moreover, in the case of the high voltage vacuum interrupter 1 in which the electrodes 3 and 2 are large, the coil electrode 3
It is common to provide a reinforcing body 4 as described above to withstand shocks and vibrations when inserting and cutting the insert 2. Moreover, this reinforcing body 4 is designed to make it difficult for leakage current that causes a decrease in magnetic flux density to flow.
Its shape is as shown in FIG.
2a, 42b, 42c, and 42d, and a space 45 is usually formed between each arm. For this reason, not only the shapes of the outer circumferential side surfaces of the electrodes 3 and 2 become more complicated, but also the shapes of the backs of the electrodes 3 and 2 also become more complicated.

On the other hand, the outer peripheral portion 43a of this reinforcing body 4
The portion (see FIGS. 2 and 4) has a sufficient radius because it can be rounded when the reinforcing body 4 is lathed. However, since the gap 44 that divides the arc member 43 is formed by cutting a cutter, and the space 45 forming each arm is formed by a milling cutter or the like, the arc parts located on both sides of the gap 44 43 and the edges of each portion located around the space 45 are in an edge state. However, because the reinforcement body 4 is made of stainless steel, the gaps 44 and 45 are narrow, and the sanding work is done by hand, it is extremely difficult to round these edges, and cutting them is difficult. The burrs during machining were removed, or even if a radius was formed, it was very small, so the electric field was likely to concentrate.

Furthermore, the shape of each arm 42a, 42b, 42c, 42d in the radial direction is such that the inner boss 41 side is larger due to bending stress, while the outer arcuate member 4 is larger.
It has a shape as shown in FIG. 2 with the third side smaller. For this purpose, on the back 4a side of the reinforcing body 4, the boss 41 located at the periphery of the space 45, the arms 42a, 42b, 42c, 42d and the arc member 4
The edge portion 3 tends to concentrate the electric field and is in a state where it faces the main shield body 17.

For this reason, when the vacuum interrupter 1 comprising the electrodes 3 and 2 as described above was subjected to a withstand voltage test using an impulse voltage, it was found that
It has been found that the electric field is concentrated on the sides and back of the main shield body 17, and this causes a flash short between the electrode 3 or 2 and the main shield body 17.

One possible solution to this problem is to increase the inner diameter of the main shield body 17 and separate it from the electrodes 3 and 2, but this is not preferable because it increases the size of the vacuum interrupter 1. .

Another method is to provide an auxiliary shield 5 on the back of the reinforcing body 4 (lower side in the figure) to alleviate the electric field in this area, as shown in FIG. It is conceivable that the side and back portions of the electrode 3 are surrounded by an auxiliary shield 5a shown in FIG. However, in the former case, the electric field relaxation effect on the outer circumferential side of the electrode 3 is not sufficient, and the ends of the coil electrode 32 and the reinforcing body 4 face the main shield body 17 even at the edges, so there is no flash. This makes it difficult to further improve the withstand voltage.

On the other hand, in the latter case, since the electrodes 3 and 2 do not directly oppose the main shield body 17, the above-mentioned problem is solved, but the gap between the auxiliary shield 5a and the main shield body 17 becomes shorter. Therefore, a flashover occurs and the withstand voltage decreases, and if this gap is increased, the vacuum interrupter 1 becomes larger, which causes a new problem.

The present invention has been made in view of the above points, and a vacuum interrupter is constructed by machining at least the portion facing the main shield body of each edge portion of the reinforcing body forming the electrode by electrical discharge melting. This provides a vacuum interrupter with improved withstand voltage.

Next, one embodiment of the present invention will be explained based on FIGS. 5 to 7. In these figures, the same reference numerals as those in FIGS. 1 to 4 described above indicate equivalent products. Therefore, detailed explanations of these will be omitted.

Reinforcement body 4 made of a non-magnetic and high-resistance material (for example, austenitic stainless steel, Inconel)
is formed with an arc portion 46 erected on the outer periphery of a circular arc member 43, and the arc portion 46 and the circular arc member 43 form a substantially hook-shaped cross-sectional shape in the radial direction. As shown in FIG.
It is to be joined to the outer circumferential surface of c). Further, by setting the standing height (the vertical dimension in FIG. 5) of the arc portion 46 to a required dimension, the arc member 43 and the arc portion 46 of the reinforcing body 4 can be connected to the coil electrode 32. When the arcuate portion 32c of the two members is joined by the brazing filler metal 48 disposed between the two members, the melted brazing filler metal 4
8 is exposed on the outer side of the electrode and does not face the main shield body (not shown).

On the back 4a side of the reinforcing body 4, as shown in FIG.
1. The edges of the arms 42a, 42b, 42c, 42d and the arc portion 43, as well as the radial void 44
Arms 42a, 42d located on both sides of the arc member 4
The edge portion of No. 3 is rounded. This rounding process is performed by arranging a movable electrode (not shown) facing the edge portion indicated by the dotted line with an arbitrary gap, and applying a high voltage between the electrode and the auxiliary body 4 to generate an electric discharge. After the corners of the edge portion are melted by electric arc melting, they are solidified to form the edge portion into a beaded shape. This bead-like edge part is formed once the edge part melts and becomes bead-like due to surface tension.
Since it solidifies as it is, the surface becomes a very smooth radius and there are no curved surfaces. Therefore, electric field concentration is alleviated and dielectric strength is significantly improved.

In addition, the outer corner portion 43a of the circular arc member 43 and the tip portion 46 of the arc portion 46 of the reinforcing body 4 may be rounded, especially on the outer circumferential side, by the above-mentioned electric discharge melting method. 4, it can be rounded at the same time when the reinforcing body 4 is formed by lathe processing, and rounding by electric discharge melting is not necessary.

In addition, in the present invention described above, the cylinder 11 of the vacuum container 10 forming the vacuum interrupter 1 is made of a metal member, and either the end plate 12 or 13 is made of an insulator, and the cylinder 11 is made of the above-mentioned main shield. It was also used as a body.

In the vacuum interrupter 1 of the present invention comprising the reinforcing body 4 as described above, the surface of the portion facing the main shield body 17 of each edge portion of the reinforcing body 4 is melted by electric discharge melting. Because of the smooth radius treatment, the electric field will not be concentrated, and there will be no chance of a flash short circuit between the main shield body 17 and the vacuum interrupter 1. The withstand voltage can be improved.

In addition, the rounding process is not done by sanding as in the past, but by beading using electric discharge, so the workability is extremely good and it is possible to perform a simple and sufficient rounding process. be.

Note that if the vacuum interrupter of the present invention is used in conjunction with the auxiliary shield 5 provided along the back 4a of the reinforcing body 4 as explained in FIG. It is possible to improve the withstand voltage.

Further, in the present invention, as described above, the vacuum interrupter 1 has the cylinder 11 made of an insulator and the end plate 12
The cylinder 11 forming the vacuum vessel 10 is not limited to the one in which the vacuum vessel 10 is formed by using metal members and the main shield body 17 inside, and the cylinder 11 forming the vacuum vessel 10 is made of a metal member and can also be used as a shield body. done,
Also, in a vacuum interrupter in which either one of the end plates 12 or 13 is formed of an insulating material,
It can be implemented in the same manner and produces similar effects.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a typical vacuum interrupter.
Fig. 2 is a cross-sectional front view of a conventional electrode, Fig. 3 is a perspective view of a conventional coil electrode, Fig. 4 is a perspective view of a conventional reinforcing body, and Fig. 5 is an electrode of an embodiment of the present invention. 6 is a perspective top view of the reinforcing body of FIG. 5, and FIG. 7 is a perspective bottom view of the reinforcing body of FIG. 5. 1... Vacuum interrupter, 10... Vacuum container,
15, 16... Lead rod, 17... Main shield body, 2, 3... Electrode, 31... Arc electrode, 32
... Coil electrode, 32b ... Arm, 32c ... Arc portion, 4 ... Reinforcement body, 41 ... Boss, 42a, 42
b, 42c, 42d... arm, 43... arc member,
44... void, 45... space.

Claims (1)

[Claims] 1 A pair of electrodes that can be brought into contact and separated from each other are provided in a vacuum container comprising an insulator via a lead rod, and the electrodes serve as a contact part with an arc electrode and a magnetic field connected to the arc electrode and parallel to the arc. A coil electrode comprising a circular arc portion for generating a ring, a ring-shaped boss surrounding and fixed to the lead rod, circular arc members provided in the same number as the circular arc portions included in the coil electrode, and these circular arc members. a reinforcement body made of a resistance member having a plurality of radially extending arms coupled to a boss, and a shield body surrounding the electrode is provided in the vacuum vessel, the vacuum interrupter comprising: At least the edges of the space formed between the arms, the boss and the circular arc member among the respective edge portions of the reinforcing body, and the edges of the arms and circular arc members located on both sides of the space between adjacent circular arc members. A vacuum interrupter characterized in that the part and part are formed into a round shape by electric arc melting.