JPS62229728A - Vacuum interruptor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a vacuum interrupter, and more particularly to a so-called vertical magnetic field type vacuum interrupter that applies an axial magnetic field parallel to an arc.

B1 Summary of the Invention A metal container is provided at one end of an insulating cylinder forming a vacuum container, and a pair of electrodes to which an electrode rod is connected is provided inside the metal container, and the inner wall of the insulating cylinder of the vacuum container and the electrode rod are connected by a shield. In a vacuum interrupter that is separated, the dimensions of the inner wall of the shield and the outer wall of the electrode rod, the dimension between the electrode surface located on the insulating cylinder side and the free end of the shield, the dimension of the outer diameter of the electrode, etc. are set in a predetermined dimensional relationship. This allows the vacuum ink crack to be made smaller without reducing the withstand voltage characteristics.

C1 Conventional technology A so-called vertical magnetic field type vacuum interrupter that applies a magnetic field parallel to the arc (axial magnetic field) between electrodes has a magnetic field generating coil (hereinafter referred to as a coil) installed inside the vacuum container, especially at the back of the electrode. , some are installed outside the vacuum container. Moesha, which has a coil electrode directly attached to the back of a pair of electrodes, has a weak point in terms of strength and durability (20 year guarantee).
There is a problem with this.

An example of an external coil system that does not have such difficulties is to provide a coil outside the vacuum vessel, place a pair of electrodes on one side of the vacuum vessel, and surround the electrodes with a single coil, thereby creating a vacuum interrupter. Japanese Patent Laid-Open No. 79921/1984 is an example of a device that aims to reduce the size and cost of the device, and improves durability and heat generation.

This will be explained with reference to FIGS. 5 and 6. 1 is a vacuum container, and the vacuum container l includes an insulating cylinder 2 made of glass or ceramics, and one end side of this insulating cylinder 2 (lower end side in the figure).
The end plate 3 made of metal seals the insulating cylinder 2, and the other end side (
A metal container 4 made of non-magnetic stainless steel is airtightly connected to the upper end side). This metal container 4 has a ceiling plate 4a and is formed into a substantially cup shape, and has an arc extinguishing chamber 20 inside. A shield 6 made of non-magnetic stainless steel is provided in the upper part of the metal container 4 so as to cover an annular metal fitting 5 provided on the insulating tube 2 and a part of the insulating tube 2.

A fixed electrode rod 7 having an electrode 11 at its inner end is provided to penetrate through the ceiling plate 4a of the metal container 4 in an airtight manner. In addition, a movable electrode rod 9 having an electrode 8 at the inner end is provided airtightly and movably through the end plate 3 that seals the other end of the insulating cylinder 2 via a bellows 10. It is. A shield 12 made of non-magnetic stainless steel is provided on the movable electrode rod 9 so as to cover the bellows 10. 3a is an auxiliary shield provided inside the end plate 3.

Reference numeral 13 denotes a substantially cylindrical coil, which surrounds the outer periphery of the metal container 4 via a gap A, and also connects a pair of electrodes 1.
1 and 8 so as to still surround them when they are shut off. The coil 13 includes a coil body 13a formed in a substantially l-turn cylindrical shape with a slit at one location, and a coil body 13a located at one end in the axial direction of the coil body 13a.
A pair of first arms 13b and a second arm 13c are arranged in parallel to each other and extend radially inward from both ends of the arcuate direction of the arm 3a. It is configured to include a first base portion Hd and a second base portion L3e.

The first base portion 13d is provided with a through hole 14, into which the outer end portion 7a of the fixed electrode rod 7 is fitted and connected. Second base 13e
is arranged with a space 15 in between, and one end of an external connection conductor 16 formed in a substantially cylindrical shape is connected to this. Also, 17
18 is a spacer made of a non-magnetic material, and 18 is a reinforcing body.

To explain the flow of current in the vacuum interrupter configured as above, for example, the current that enters from the external connection conductor 16 flows from one end of the coil body 13a to the other via the second base 13e and the arm 1 (c). flows in a loop toward the end of the arm 13b, and at this time generates a so-called longitudinal magnetic field parallel to the arc generated between the electrodes.
It reaches the fixed side electrode rod 7 via the base 13d. It then reaches the movable electrode rod 9 via the electrode 11 and the other electrode 8 (which generates an arc when disconnected).

In the vacuum interrupter, when opening the electrode 11.8
Although metal vapor is generated due to the arc generated between the two, these metal vapors adhere to the shield 6 and do not stain the inner wall of the insulating cylinder 2, thereby preventing a decrease in the withstand voltage characteristics of the vacuum interrupter. .

D0 Problems to be Solved by the Invention By the way, vertical magnetic field type vacuum interrupters generate less metal vapor when cutting off the current than the so-called spiral type vacuum interrupters that drive the arc in rotation, so it is difficult to prevent contamination inside the vacuum interrupter. The shield structure for this is relatively simple.

However, in recent years, vacuum interrupters have a rated breaking current of 100 times or more, for example.
Moreover, large current interrupting performance is required. In order to meet the above-mentioned requirements with a vertical magnetic field type vacuum interrupter, the conventional shield structure is insufficient to ensure the internal creepage distance of the vacuum container and prevent contamination. In order to avoid this problem, it would be possible to use a crossed shield as used in spiral type vacuum interrupters, but in that case, the external size of the vacuum interrupter would increase, which is contrary to miniaturization, miniaturization, and cost reduction. This may cause problems.

Means for Solving Problem E1 Therefore, the present inventor focused on the above problem and developed the above structure (
We conducted repeated experiments and conducted research to further reduce the size of the vacuum interrupter shown in Figure 5 and improve its interrupting performance. As a result, it was found that there is a correlation between the mutual arrangement of the shield and other members in the withstand voltage characteristics of the vacuum interrupter.

Experimental examples leading to the present invention will be explained below.

The experiment was conducted using a vacuum interrupter having the structure shown in FIG. First, the vacuum interrupter shown in FIG. 2 will be described with the same reference numerals assigned to the same parts as those of the conventional example shown in FIG. 5.

The insulating tube 2 is made of alumina ceramics, and one end of the insulating tube 2 is closed by a metal container 4 made of non-magnetic stainless steel via an annular fitting 5 made of a Cu material. The other end of the insulating cylinder 2 is hermetically closed with an end plate 3 made of Fe-Ni-Co alloy (Kovar). Electrodes 1 are located in the metal arc extinguishing chamber 20 formed by the metal container 4 and are located at the inner ends of the fixed side and movable side electrode rods 7°9, respectively.
1 and 8 are provided.

The pair of electrodes 8 and 11 is made of a powder composite metal material consisting of Cu, 35% by weight of Mo, and 5% by weight of Cr. Reference numeral 19 denotes a shield made of non-magnetic stainless steel, which is provided on the movable electrode bar 9 at the back side of the movable electrode 8 . The shield 19 is almost funnel-shaped with an expanded upper part.
The maximum diameter portion is provided to have approximately the same size as the electrode diameter, and the tip portion is bent toward the back side of the electrode.

A shield 21 extending in the axial direction is provided at the lower end of the metal container 4 so as to cover a portion of the insulating cylinder 2 on the metal arc extinguishing chamber side.

This shield 21 is made of non-magnetic stainless steel. Further, a shield 12 provided on the movable electrode rod 9 so as to cover the outside of the bellows IO is made of non-magnetic stainless steel. Further, the coil 13 surrounding the outer periphery of the metal container 4 via the gap A has one end side of the circular arc portion connected to the outer conductor 2.
The outer end of the fixed electrode rod 7 is fitted into a through hole 23 at the tip of an arm 13f extending radially inward from the other end of the arc portion.

Experiment 1 In a vacuum interrupter made of the above structure and materials,
First, we conducted the following experiment. In this experiment, the electrode diameter D = 50 am (the taper angle around the outer diameter of the contact part was 30 mm), the diameter of the movable electrode rod d = 22 mm, the opening gap G = 8 *ttr, and the shield The inner diameter of, (change) the distance between the movable electrode surface and the free end of the shield when the contact is open, Q, C change) the gap between the inner wall of the shield and the outer wall of the electrode rod, C, (change) and If so, D+, L+ 121. We investigated what kind of correlation Qt has with the withstand voltage characteristics.

That is, if the metal base l< generated between the electrodes adheres to the inner wall surface of the insulating cylinder 2, it will most likely affect the withstand voltage characteristics of the vacuum interrupter. From this, it is clear that the shape of the shield 21, that is, the inner diameter of the shield 7. Based on the distance Q between the movable side electrode surface and the free end of the shield at the time of opening, the shield 21 becomes a metal vapor movement path.
The relationship between the distance e between the electrode rod 9 and the electrode diameter D1 of the metal vapor source was investigated.

experiment! [1, L) Various dimensions and -) 12kV -
The withstand voltage characteristics were investigated after 25 kA was interrupted 100 times.

(In addition, Q3 is the dimension between the shields 19 and 21 when the contacts are opened, and Q, = Q, is closed. Also, when h = 70 or more, vl becomes a large diameter, so for anything larger than that, experiment (In addition, Q was slightly thicker than G = 8 zyr, and lOum was taken as the minimum value.) The results of the experiment are shown in FIG. Note that the results are shown as a ratio to the initial withstand voltage value. In the same figure, curve A shows the minimum value in the cases of Examples -1, -2, and -3, curve opening shows the minimum value in the cases of Examples -4 and -5, and curve C shows the minimum value in the cases of Examples -6°- The minimum value in case of 7 is shown. Therefore, from the above results ■D, > D, + 12++
In the case of +at (Example -6, -7), the shield must be made considerably long as shown in curve C (L/Qt>tO)
, was found to be unsuitable for practical use.

■In the case of D, <D, ≦D, +8 am (example -4, -5), the inner wall of the insulating cylinder 2 tends to be easily contaminated like the curved opening, but (1, /Q, ≧5 I found out that it would be a good idea to do this.

■When D, = (D, -8) ~ D, am (Example -1 ~ -
For 3), it has been found that it is sufficient to set Q, /Qt≧4, as shown in curve A.

Furthermore, it has been found that when Q, /Q, is 4 or 5 or less than 8, the inner wall of the alumina ceramic is contaminated by the adhesion of metal vapor generated during shutoff, and as a result, the withstand voltage characteristics are significantly lowered.

Experiment 2 Therefore, in the vacuum interrupter with the dimensional relationship shown in Example 2 in the table above and the structure shown in FIG. 2, Ql/Qt=
5. Experiments were conducted with a dimensional relationship of QI/l2t=3.

In the experiment, 12 kV-25 kA was cut off, and the withstand voltage value was measured every 50 times. The experimental results are shown in the graph of FIG. 4 as a ratio to the initial value. In the same figure, curve a is Ql/Qt=
5, b is the result for the relationship Q, /Qt=3.

As can be seen from the figure, when Q, /Q, = 5, the number of interruptions is 1.
It can maintain 80% of the initial voltage resistance up to 50 times.
The withstand voltage characteristics were significantly improved.

On the other hand, when Ql/Q2=3, the withstand voltage characteristic could be maintained at 80% of the initial value up to 100 times, but it significantly decreased after 150 times. Incidentally, the dimensions of a conventional vacuum interrupter are generally set at approximately Q, /ρ, and #3.

In addition, in the case of cutting off at the dimension of curve a, that is, C, #, = 5, metal vapor adhered to the shield 21 and the withstand voltage characteristics deteriorated, and the inner wall of the insulating cylinder 2 There was no metal vapor attached. curve, that is, C
, /12t=3, the particles adhered not only to the inner peripheral surface of the shield 21 but also to the inner wall of the insulating cylinder 2. This is thought to be the reason for the significant drop in withstand voltage characteristics.

From the results of Experiment 1.2 above, when D, = (D,'-8) ~ D-shoulder, (21/i2
．． ≧4, D, Q when <Dt≦D++8Ri, /σ,
If ≧5, it was found that when a large current of 12 kV-25 kA was interrupted 150 times for the former and 100 times for the latter, it was possible to maintain voltage resistance characteristics of 80% of the initial value.

The present invention has been made based on the above results. That is, an insulating tube and a metal container provided at one end of the insulating tube form a vacuum container, a pair of relatively movable electrodes are provided in the metal container, and an electrode rod is connected to one electrode. At the same time, the electrode rod is inserted through the insulating tube, and a shield is provided at the same potential as the metal container, and is located between the electrode rod and the insulating tube and extends in the axial direction so as to separate them.
In the vacuum interrupter configured by providing a coil for applying an axial magnetic field between the pair of electrodes, the outer diameter of the electrode is Dl.
, the inner diameter of the shield is Dz, and the gap dimension between the inner wall of the shield and the outer wall of the electrode rod Q7. When the distance between the electrode surface located on the insulating cylinder side and the free end of the shield is Ql, D,
(D, -8) to (D, + 8) am and Q, /Q,
It was configured to have a relationship of ≧5. Furthermore, D,=(D,
-8) to D1R11, and the relationship is 121/(2t≧4).

F. EXAMPLE The present invention will be explained below based on the example shown in FIG. Incidentally, the same parts as those of the vacuum interrupter shown in FIG. 2 are given the same reference numerals, and the explanation thereof will be omitted. Therefore, in this embodiment, the electrode diameter D = 50! Diameter of movable electrode rod d = 22am Opening gap G = 8i Inner diameter of skin shield, = 5011 Dimension between movable side electrode surface and free end of shield when opening L = 70z Shoulder shield inner wall and electrode rod outer wall A vacuum interrupter is shown in which the gap dimension is Qt=L4zm and the dimension between two shields 19.21 is 12a=14am.

The dimension between the movable electrode 8 and the inner wall of the vacuum container 1 is Q.
3 or more, and in the example, Q3
It is set larger. Also, dimension 12, Q is Q
It is necessary to satisfy 3≧Q2, and in the embodiment, the dimensions are the same. Furthermore, the distance between the free end (lower end) of the shield 21 and the bellows shield 12 needs to be larger than g1 when opened, and is configured in such a manner. Further, the electrode material of each electrode 11, 8 is Cu-35Mo-5
A powder composite metal of Cr was used.

These pair of electrodes 11 and 8 have a recess 2 at the center of their surface.
5, and a ring-shaped contact portion 11a on the outer periphery of the recess 25.

8a, and an electrode having a taper 24 at an angle of 4 degrees from its outer periphery to the electrode periphery was used. Furthermore, the thickness of the electrode 11.8 is 5 mm, the depth of the recess 25 is IMR, the inner diameter of the ring-shaped contact portion 11a, 8a is 20 ix, and the outer diameter is 30 mm.
rpm.

12kV-25k using the vacuum interrupter with the above structure.
When the 'ri flow of A was cut off, the withstand voltage characteristics of 80% of the initial value could be maintained up to 150 times.

Although not shown in the drawings, if the electrode rod inserted through the insulating tube 2 is a fixed electrode rod, or if the magnetic field generating coil is arranged inside the metal arc extinguishing chamber 20, the arrangement of the magnetic field generating coil 13 may be changed. The test was also performed on the back of the movable electrode. As a result, it was possible to maintain excellent withstand voltage characteristics similar to those of the vacuum interrupter having the structure shown in FIG.

G1 Effects of the Invention As described above, according to the present invention, a vacuum interrupter with long-term stable voltage resistance characteristics can be obtained, and the relationship between the electrode shape of the metal vapor source and the shield shape can be optimized. , it is possible to manufacture a vacuum interrupter that is the most compact among those with the same rating, thereby reducing manufacturing costs and, in turn, reducing the size of the vacuum switchgear.

It becomes possible to reduce costs.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a vacuum interrupter according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of a vacuum interrupter used in experiments of the present invention, FIG. 3 is a graph showing the results of experiment 1, and FIG. Graft showing the results of Experiment 2... Vacuum container, 2... Insulating cylinder, 4... Metal container, 7... Fixed side electrode rod, 8...
...Movable side electrode, 9...Movable side electrode rod, 11...Fixed side electrode, 13...Coil, 2o...Metal arc extinguishing chamber,
21...Shield. Part ■ Kula 482 Figure 3! 4s4 (support) 0 50 100 150
20OLJP-Determined Mohi @Figure 5 1 Old

Claims (7)

[Claims] (1) An insulating cylinder and a metal container provided at one end of the insulating cylinder form a vacuum container, a pair of relatively movable electrodes is provided in the metal container, and an electrode rod is connected to one electrode. At the same time, the electrode rod is inserted through the insulating cylinder, and a shield is provided between the electrode rod and the insulating cylinder and extends in the axial direction so as to separate the two, at the same potential as the metal container. In the vacuum interrupter configured by installing a coil that applies an axial magnetic field between the pair of electrodes, the electrode outer diameter is D_1, the shield inner diameter is D_2, the gap size between the shield inner wall and the electrode rod outer wall is l_2, and the insulating cylinder side is When the distance between the surface of the electrode and the free end of the shield is l_1, D_2=(D_1-8)~
(D_1+8) mm, and l_1/l_2≧5. (2) A vacuum container is formed by an insulating cylinder and a metal container provided at one end of the insulating cylinder, a pair of relatively movable electrodes is provided in the arc extinguishing chamber, and an electrode rod is connected to one electrode. At the same time, the electrode rod is inserted through the insulating cylinder, and a shield is provided between the electrode rod and the insulating cylinder and extends in the axial direction so as to separate the two, at the same potential as the metal container. In the vacuum interrupter having a coil that applies an axial magnetic field between the pair of electrodes, the outer diameter of the electrode is D_1, the inner diameter of the shield is D_2, the gap size between the inner wall of the shield and the outer wall of the electrode rod is l_2, and the electrode is located on the insulating cylinder side. When the distance between the surface of the shield and the free end of the shield is l_1, D_2=(D_1-8)~
A vacuum interrupter characterized in that D_1 mm and l_1/l_2≧4. (3) The electrode rod inserted through the insulating cylinder is a movable electrode rod, and the dimension l_2 is the distance between the surface of the movable electrode and the free end of the shield provided at the same potential as the metal container when the electrode is opened. The vacuum interrupter according to claim 1 or 2, wherein the distance dimension is a distance dimension. (4) The vacuum interrupter according to claim 1 or 2, wherein the electrode rod inserted through the insulating cylinder is a fixed electrode rod. (5) The vacuum interrupter according to claim 1 or 2, wherein the magnetic field generating coil is provided outside the metal container. (6) The vacuum interrupter according to claim 1 or 2, wherein the magnetic field generating coil is provided inside the metal container. (7) The vacuum interrupter according to claim 6, wherein the magnetic field generating coil is provided on the back of at least one of the electrodes.