JPH0123891B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a vacuum interrupter, and particularly to a vacuum interrupter equipped with an electrode that generates an axial magnetic field (a magnetic field parallel to the arc).

<Prior Art> Conventionally, a vacuum interrupter in which the electrode itself has a function of generating an axial magnetic field to improve shearing performance has been constructed as shown in FIG.

That is, both ends of insulating cylinders 11, 11 made of ceramics, glass, etc. are connected to end plates 1 made of metal.
A pair of lead rods 15 and 16 are introduced into the vacuum container 10, which is airtightly closed by 2 and 13 and evacuated to a high vacuum, so as to be able to approach and separate from each other. It is constructed by attaching a pair of electrodes 2 and 3 to the inner ends of lead rods 15 and 16, which touch and separate (contact and separate) in order to disconnect. These electrodes 2 and 3 are arranged on the back side (lead rod side) of the arc electrodes 21 and 31 that serve as contact portions and on the back side (lead rod side) of the contact portions of these arc electrodes 21 and 31, and are arranged to direct the current flowing through the lead rods 15 and 16 to the respective leads. stick 1
5 and 16 to generate a magnetic field in the axial direction (vertical direction in FIG. 1).

Since these electrodes 2 and 3 have similar configurations, electrode 3 will be used as a representative and will be explained in more detail based on FIG.

The arc electrode 31 has a contact portion 31a in its center that contacts the mating electrode 2, and has a plurality of slits 31b cut in the radial direction from the outer periphery. The coil electrode 32 includes a boss portion 32a to which an end of a lead rod (not shown - lead rod 16 in FIG. 1) is connected, a plurality of arms 32b protruding radially outward from the boss portion 32a, and a plurality of arms 32b. Each arm 32b
The circular arc portion 32c has one end connected to the outer end of the circular arc portion 32c and is curved in the circumferential direction. This coil electrode 32 and the arc electrode 31 are integrally coupled with a high resistance spacer 33 made of a low conductivity material (for example, stainless steel material) interposed therebetween. The arc electrode 31 is connected to the arc electrode 31 via the connecting fitting 34 located in the axial direction.
It is connected on the back side of the main body and near the outer circumference.

In addition, in FIG. 1, 14 is a bellows, 17
is a shield.

By the way, there are many problems that need to be solved in order to improve the shearing performance of the vacuum interrupter as mentioned above, but the most relevant to improving the shearing performance is the problem with the coil electrode and arc electrode. It is a solution.

First, we will discuss the coil electrode.

The coil electrode generates an axial magnetic field, and the shearing performance is greatly affected by the strength (density) of this magnetic field. In order to obtain a high-density magnetic field, a coil electrode may be formed by winding a conductor once or multiple times, but this increases the length of the loop circuit and generates significant heat. To prevent this, it is necessary to use a fairly thick conductor, and the vacuum interrupter becomes very large, so one turn is usually made into a 1/4 inch conductor, as shown in Figure 2 above.
A so-called 1/4 branch (1/4 turn) is formed by combining four divided arc parts 32c, or a current is branched by forming a 1/3 turn or 1/2 turn with a reduced number of divisions. is used.

If the current is divided in this way, the current shared by each arcuate portion 32c of the coil electrode is reduced, so heat generation can be prevented, and the cross-sectional area of the arcuate portion etc. can be reduced, which has the advantage of forming a small electrode. Since one turn of the electric path is divided into a plurality of parts, as the number of divisions (the number of branched currents) increases, the effective circular arc portion of the coil decreases, resulting in a problem that the magnetic flux density decreases.

For this reason, the opening gap (distance between a pair of opposing electrodes at the time of opening) is 30 to 60 mm.
For vacuum interrupters that are large in size (for example, for high voltage applications or capacitor switching applications), it is desirable to use a 1/2 turn coil electrode that can obtain a large magnetic flux density.

However, as the magnetic flux density increases, eddy currents are more likely to occur in the arc electrode, which impairs the shearing performance, so the arc electrodes must be formed in such a way that eddy currents will not occur.

Next, we will discuss the arc electrode.

The arc electrodes 21 and 31 of the electrodes 2 and 3 in the vacuum interrupter as described above are generally made of a material with high conductivity such as Cu.
In this case, there is a problem that eddy current flows in the arc electrodes 21, 31, and the magnetic flux density of the axial magnetic field generated by the coil electrodes 22, 32 decreases.

In order to deal with this problem, it has been proposed that the arc electrode 31 (and 21) is provided with a plurality of radial slits 31b as shown in FIG. 2, but each slit 31b has an electrode diameter of 100 mm. If it is more than 100%, it is necessary to make the radial cut deeper. Therefore, the strength of the arc electrode 31 (and 21) decreases, and the slit 31b
There is a problem that the edges reduce the withstand voltage. This tendency becomes a problem in cases where a high shear breaking speed and a high withstand voltage are required, such as in a high-voltage vacuum interrupter. Moreover, if a large current is applied and cut off many times, the electrode material will melt and the slit will become loose, resulting in an increase in eddy current and a problem in that the cutting performance will deteriorate.

Furthermore, in order to deal with the above-mentioned problems, it has been proposed that the arc electrode 31 (and 21) is formed of a material with low conductivity without providing the slit 31b. In this case, materials with a conductivity of 30-40% or less (e.g. beryllium,
Arc electrodes 31, 21 by Cu-W, Ag-W)
If formed, the generation of eddy current is considerably reduced, there is no need to provide slits, and there are advantages that the withstand voltage and mechanical strength can be improved.

However, when the arc electrode is made of a material with a low conductivity of 30 to 40% or less, there is a problem in that heat generation becomes significant when electricity is applied.

That is, since the tip of the circular arc portion 32c located on the outer circumferential side of the coil electrode 32 is connected to a portion closer to the outer circumferential side of the arc electrode 31 via the connecting fitting 34, the tip of the arc portion 32c located on the outer circumferential side of the coil electrode 32 is connected to the outer circumferential side of the arc electrode 31 via the connecting fitting 34. As shown,
The currents I ₁ , I ₂ , I ₃ , and I ₄ form long electric paths in the radial direction within the arc electrode 31, thereby generating significant heat.

In addition, since the resistance of the arc electrode 31 is large,
Since the total resistance of the electric path formed by the arc electrode 31 and the coil electrode 32 becomes large, the current that is shunted to the high resistance spacer 33 increases, and as a result, the current flowing to the coil electrode 32 decreases. , problems arise when the magnetic flux density decreases.

<Problems to be Solved by the Invention> In order to solve the above-mentioned problems in electrodes equipped with arc electrodes made of materials with low conductivity, the present inventor has developed a structure in Japanese Patent Application No. 56-84233 (Japanese Unexamined Patent Publication No. 56-84233). Showa 57
199126), and the electrode thereof has a structure as shown in FIGS. 4 and 5.

That is, a boss part 41, a plurality of arms 42 (same number as the arms 32b of the coil electrode 32) projecting outward from the boss part 41 in the radial direction, and connecting parts 43 provided at the outer ends of each arm 42. and an adapter 4 made of a highly conductive material (for example, Cu),
Back part of arc electrode 31 (opposite side of contact part 31a)
The connecting portion 43 of each arm end of the adapter 4 and the end of the arc portion 32c of the coil electrode 32 are connected by a connecting fitting 34.

According to this configuration, the current I when energized is
As shown in FIG. 4, the contact portion 31 of the arc electrode 31
From a, an axial electric path (thickness direction electric path) is taken in the arc electrode 31, and the electric current flows to the boss portion 41 of the adapter 4, and is then branched to each arm 42 and flows through the connecting fitting 34 to the coil electrode 32. Furthermore, it will flow to the lead rod 16. As a result, the electrical path within the arc electrode 31 with high resistance is extremely short because it is formed in the axial direction (thickness direction), which solves the problem of heat generation.
The current shunted to the magnetic field decreases, and the resulting decrease in magnetic field density can also be prevented.

Therefore, from the above, a large magnetic field density can be obtained by forming the coil electrode in a 1/2 turn coil shape, but as the magnetic flux density increases, the generation of eddy current in the arc electrode increases proportionally. As a result, there is a problem that the magnetic flux density decreases and the shearing performance deteriorates, so the combination with an arc electrode is an important requirement in order to improve the shearing performance.

To prevent the generation of eddy current in this arc electrode, the arc electrode should be
If it is made of a material with a low electrical conductivity of 40% or less, it can be constructed without providing radial slits that would cause a decrease in withstand voltage. However, if the arc electrode is made of a material with low conductivity, the arc electrode will generate significant heat when energized, but this can be prevented by providing an adapter made of a material with high conductivity on the back of the arc electrode as described above. Problems are solvable.

In view of the above points, the present invention combines an arc electrode made of a material with low conductivity, an adapter made of a material with high conductivity provided on the back of the arc electrode, and a coil electrode made of a material with high conductivity. The object of the present invention is to provide a vacuum interrupter in which a large magnetic flux density is obtained by forming an electrode that generates an axial magnetic field, and the shearing performance is improved.

<Means for Solving the Problems> The present invention provides a vacuum container in which a pair of electrodes are arranged facing each other so as to be able to come into contact with each other through electrode rods, and an arc electrode in contact with the opposing electrode is connected to the electrode rod through a high-resistance spacer. a coil electrode supported on the opposite side of the arc electrode, connected to the electrode rod and the arc electrode, and generating an axial magnetic field by converting the current flowing through the electrode rod into a loop current centered on the electrode rod; A vacuum interrupter comprising: a boss portion for attaching the coil electrode to the inner end of the electrode rod; a plurality of arms provided on the boss portion extending in the radial direction; and a plurality of arms extending in the circumferential direction from the ends of the arms. The arc electrode is made of a material with high conductivity and has an arcuate portion that is concentric with the electrode rod and extends close to the adjacent arm, and the arc electrode is formed in the shape of a hat-shaped disk with an opposing surface made of a material with low conductivity. , a boss portion on the back surface of which the high resistance spacer is attached; arms provided on the boss portion and extending in the radial direction, the number of which is the same as the number of arms of the coil electrode; and a circular arc of the electrode from the end of the arm. An arcuate portion curved in an arcuate direction in the circumferential direction opposite to the coil electrode with approximately the same radius as the electrode rod, and extending from the end of the arm in the circumferential direction to near the adjacent arm that is concentric with the electrode rod. The present invention is characterized in that the adapter is formed by brazing an adapter made of a material with high conductivity, and the end of the coil electrode and the end of the arc portion of the adapter are electrically connected with a connecting fitting.

<Function> Between the arc electrode and the electrode rod, current flows in an arc-shaped loop in the coil electrode, and this loop current is further extended into an arc shape by the adapter, resulting in a large magnetic flux density. can get.

<Example> Next, an example according to the present invention will be explained based on FIGS. 6 to 9. In these figures, the same reference numerals as in FIGS. 1 to 5 described above indicate equivalent products. , so a detailed explanation of these will be omitted.

First, what is shown in FIGS. 6 to 8 is one of a pair of electrodes included in a vacuum interrupter according to an embodiment of the present invention, and the arc electrode 31 forming this electrode 3 is , with a contact part 31a in the center thereof, made of a material with a low conductivity of 30 to 40% or less (for example, beryllium, Cu-W,
It is made of electrode material such as Ag-W, Cu-Cr, etc., and is formed into a hat-shaped disk shape.

Next, the coil electrode 32 has a central boss portion 32a that is connected to the lead rod 16, and a central boss portion 32a that is connected to the lead rod 16.
a pair of radially located arms 32b connected to
and a pair of 1/2 arms each having one end connected to each outer end of these arms 32b, curved so as to surround the boss portion 32a, and the other end extending close to the other arm 32b. 2-turn arc portion 32c
It is formed with

The adapter 4 made of a highly conductive material (for example, Cu), which is provided on the back of the arc electrode 31 and is integrally formed with the arc electrode 31, has a pair of arms 42 whose inner ends are connected to the boss portion 41. and an arcuate portion 44 which has one end connected to the outer end of each arm 42, the other end of which is close to the other arm 42, and is curved in the circumferential direction so as to surround the boss portion 41. It is formed. In addition, the boss portion 41 of the adapter 4 is embedded in the back of the arc electrode 31 to achieve radial positioning, and the arm 42 and the arc portion 44 are brought into close contact with the back of the arc electrode 31. and the arc electrode 31 are integrally formed by brazing or the like.

The connection between the adapter 4 and the coil electrode 32 is made by using the tip 4 of the arcuate portion 44 of the adapter 4.
4a and the distal end in the extending direction of the 1/2 turn circular arc portion 32c of the coil electrode 32 are faced to each other and overlapped in the axial direction, and mechanical and electrical connections are made through the connecting fitting 34 located in the axial direction. The electrodes 3 are connected to each other to form the required electrodes 3.

In this way, the arc portion 44 of the adapter 4
If it is extended to the vicinity of the other arm 42, a large magnetic flux density can be obtained.

Further, a recess 41a is provided in a portion of the boss portion 41 of the adapter 4 located on the coil electrode 32 side. One end (upper end) of a high resistance spacer 33 made of a conductive material is recessed.

Furthermore, the adapter 4 and the boss portion 32 of the coil electrode 32
In order to fix the arc electrode 31 to the end of the lead rod 16, a high-resistance spacer 33 made of, for example, stainless steel is interposed between the lead rod 16 and the lead rod 16.

In addition, in FIG. 6, 35 is a coil electrode 32 made of a material with low conductivity (for example, stainless steel material).
As shown in FIG. 8, this reinforcing body 35 includes a ring-shaped boss portion 35a surrounding the lead rod 16, and a plurality of arms 35b connected to the boss portion 35a and positioned in the radial direction. and are connected to the outer ends of the plurality of arms 35b, respectively, and are formed in an arc shape having substantially the same shape as the arc portion 32c of the coil electrode 32, and have different surfaces (a plane portion and a side surface) forming the arc portion 32c. arc portion 35 joined to
c.

Further, the lead rod 16 includes a lead pipe 16a made of a material with high conductivity (for example, Cu), and a core 1 made of a material with high mechanical strength (for example, stainless steel material) buried in the lead pipe 16a.
6b, and an auxiliary fitting 16c that airtightly connects both members at their shaft ends.

In the electrode 3 configured as described above, the current flows in an arc-shaped loop in the coil electrode 32 between the arc electrode 31 and the lead rod 16,
Moreover, this loop current is further expanded into an arcuate shape by the adapter 4 to generate an axial magnetic field.

Next, FIG. 9 shows the magnetic flux density distribution in a vacuum interrupter equipped with the electrode of the present invention. In addition,
The diameter of the coil electrode used in the experiment was 120 mm.
The horizontal axis is the electrode radius Rmm, and the vertical axis is the magnetic flux density G/KA
This figure shows the magnetic flux distribution in the right half of the electrode from the center. In addition, A, B, C, and D in this figure are the magnetic flux densities at different gap sizes between poles, where A is a gap of 15 mm, B is a gap of 30 mm, and C is a gap of 45 mm.
mm and D indicate the case where the gap is 60 mm.

<Effects of the invention> As is clear from the above explanation, the conductivity is 30~
Arc electrode 31 made of 40% or less material
The electrode 3 of the present invention includes an adapter 4 made of a highly conductive material provided on the back side of the arc electrode 31, and a coil electrode 32 that shunts current into a loop current to generate a transverse magnetic field. Such a vacuum interrupter has various effects as described below.

Since the coil electrode 32 divides the current into 1/2 turns, the effective length of the circular arc portion 32c that generates the magnetic field is long, and a large magnetic flux density can be obtained.

Since the arc electrode 31 is made of a material with low conductivity, even if a large magnetic field is applied by the 1/2 turn coil electrode 32, almost no eddy current that causes a decrease in magnetic flux density is generated. Moreover, since there is no need to provide a radial slit to prevent the generation of eddy current, it is possible to improve the withstand voltage characteristics and the shearing characteristics when the contacts are opened.

Based on the above, vacuum interrupters for high voltages require a large dimension between opposing electrodes and a large magnetic field when opening, and vacuum interrupters for opening/closing capacitors where high voltage is applied more than usual after the shear is disconnected. It is suitable for

Further, an adapter 4 made of a material with high conductivity is provided on the back of the arc electrode 31, and this adapter 4 is connected to the arc portion 3 of the coil electrode 32.
2c, and the adapter 4 is connected to the contact portion 31a of the arc electrode 31.
Since it is located at the back of the arc electrode 31, when electricity is applied, the current flows to the adapter 4 vertically in the thickness direction of the arc electrode 31, and since this electrical path is very short, there is almost no problem with heat generation. However, it is possible to provide a highly durable vacuum interrupter.

In particular, when the adapter 4 includes a pair of arcuate portions 44, and the tip 44a of each arcuate portion 44 and the tip of the arcuate portion 32c of the coil electrode 32 are arranged facing each other and overlapping in the axial direction, In this case, there is an advantage that a larger magnetic flux density can be obtained as a result of increasing the number of loops, and it is suitable for a vacuum interrupter that uses a low current and high voltage and has a large gap when opening.

[Brief explanation of drawings]

Figure 1 is a front sectional view of a conventional vacuum interrupter, Figure 2 is an exploded perspective view of the electrode in Figure 1,
3 and 4 are plan views and cross-sectional views of electrodes with other configurations, FIG. 5 is a perspective view of the adapter in FIG. 4, and FIGS. 6 to 8 are electrodes according to the present invention. 6 is a sectional view, FIG. 7 is an exploded perspective view of the main parts, FIG. 8 is a perspective view of the reinforcing body, and FIG. 9 is a magnetic flux density distribution diagram in the present invention. 1 is a vacuum interrupter, 10 is a vacuum container, 15
and 16 are lead rods, 2 and 3 are electrodes, 21 and 31 are arc electrodes, 22 and 32 are coil electrodes,
32b is an arm, 32c is a circular arc portion, 33 is a high resistance spacer, 34 is a connecting fitting, 4 is an adapter, 42 is an arm, and 44 is a circular arc portion.

Claims (1)

[Claims] 1. A pair of electrodes are disposed in a vacuum container so as to be able to come into contact with and separate from each other in a vacuum container, and an arc electrode that is in contact with the opposing electrode is supported on the electrode rod via a high resistance spacer, and the anti-contact of the arc electrode is A vacuum interrupter including a coil electrode connected to the electrode rod and the arc electrode on the side and generating an axial magnetic field by converting the current flowing through the electrode rod into a loop current centered on the electrode rod, the coil electrode comprising: a boss attached to the inner end of the electrode rod; a plurality of arms provided on the boss and extending in the radial direction; and a circumferentially adjacent arm concentric with the electrode rod from the end of the arm. the arc electrode is formed of a material with high conductivity and has an arcuate portion extending up to 100 mm, and the opposing surface is formed of a material with low conductivity in the shape of a hat-shaped disk, and a boss portion on the back surface of which the high resistance spacer is attached; and an arm provided on the boss portion and extending in the radial direction and having the same number of arms as the arms of the coil electrode, and an arm extending from the end of the arm with a radius substantially the same as the arcuate portion of the electrode and opposite to the coil electrode. An adapter made of a highly conductive material, which is curved in an arc shape in the circumferential direction of the arm, and has an arc section extending from the end of the arm in the circumferential direction to a point near the adjacent arm that is concentric with the electrode rod. A vacuum interrupter characterized in that the coil electrode is formed by brazing, and the end of the coil electrode and the end of the arc portion of the adapter are electrically connected by a connecting fitting.