JPS62278713A - Vacuum interrupter - 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] 3. Detailed Description of the Invention [Object of the Invention] (Field of Industrial Application) The present invention relates to a vacuum interrupter used in a vacuum circuit breaker, and particularly relates to an improvement in the electrode structure. be.

(Prior Art) As is well known, a vacuum circuit breaker opens electrodes in a vacuum container sealed in a vacuum, and interrupts current by utilizing the excellent insulating performance and arc extinguishing performance of vacuum. The performance of vacuum circuit breakers has improved significantly in recent years, allowing them to conduct and interrupt large currents. Conventionally, there are three main types of electrode structure used in the interrupter section of a vacuum circuit breaker: a contrast type, a spiral type, and a vertical magnetic field type (axial magnetic field type). Of these three types of electrode structures, the contrast type and spiral type electrodes are called arc-driven types, which use the magnetic field created by the current flowing through the electrode to drive the arc pole of the large current density of the vacuum arc generated when the electrode is opened. The electrode is rotated at high speed in the circumferential direction, and the arc is extinguished when the current reaches zero point so that the electrode does not get stuck in one place on the electrode surface.

On the other hand, in the conventional vertical magnetic field type electrode, as shown in FIGS. 3 and 4, the current flowing in the current-carrying shaft is connected to the coil electrode 3 on the back side of the opposing surface of the electrode 2, and the coil arm portion 3a, coil portion 3b,
In this method, the current is divided in the circumferential direction by the coil current-carrying portion 3c, and the vertical magnetic field (axial magnetic field) generated thereby causes the arc to be ignited uniformly on the electrode surface, and is interrupted when the current reaches zero point. In addition, in FIG. 3, the right half shows the back surface of the electrode part, and the left half shows the front surface of the electrode part. Figure 3.

In FIG. 4, 3d is a coil attachment part, 4 is a contact, 5 is a spacer, and 6 is a slit.

(Problems to be Solved by the Invention) In the above-mentioned arc drive type, the arc voltage is high and an arc pole with a large current density is generated, so the contact is subject to severe erosion and damage when interrupting a large current, and insulation due to roughness of the contact surface Breaking performance is limited by thermal re-ignition caused by destructive re-ignition or heat concentration due to extremely rough contact surfaces.

In the case of the above-mentioned vertical magnetic field type, the arc voltage is low and the arc is evenly distributed and ignited on the electrode surface, so the current density decreases.
Damage to the contact point 4 is also suppressed, and breaking performance is also significantly improved.

However, when the electrode is inserted, the current is shunted from the current-carrying shaft 1, and the coil electrode 3. Specifically, the coil arm portion 3a,
Since the energizing current always flows through the coil portion 3b and the coil current-carrying portion 3c, the impedance due to the resistance and inductance of the coil electrode 3 is large, and the heating opening is relatively large, which poses a problem when applying a large current when the electrodes are turned on.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a vacuum interrupter that is capable of interrupting a large current and allowing a large current to flow when turned on.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a vacuum container having fixed and movable electrodes each supported by a current-carrying shaft and arranged so as to be able to move toward and away from each other in a vacuum container. In the interchanger, a solenoid for generating a vertical magnetic field is arranged and supported in the circumferential direction around the energizing shaft on the back surface opposite to the facing surface of the fixed electrode and the movable electrode, and a solenoid for generating a vertical magnetic field is arranged and supported around the energizing shaft. There is an annular iron core in which a thin plate of high magnetic permeability material is wound in multiple layers at a position close to the solenoid, and a required number of conductive wires are wound around this iron core, and electrically connected to the solenoid coil. It is equipped with a connected annular solenoid coil.

(Function) As a result, an axial magnetic field is generated in the space between the electrodes when the electrodes are separated without dividing the current flowing through the current-carrying shaft, and a large current can be interrupted. Because the current flows directly through the electrode to the opposite electrode without being shunted to the conventional coil electrode, heat generation is suppressed and large current can be passed.

(Example) Hereinafter, an example of the vacuum interrupter of the present invention will be described with reference to the drawings. Some conventional vacuum interrupters have different structures between fixed electrodes and movable electrodes,
In this example, both electrodes have the same structure, so the following description will be made only with respect to the movable electrode. FIG. 1 is a cross-sectional view thereof, and the current-carrying shaft 20 is directly fixed by brazing or the like to the center of the opposing back surface of an electrode 21 made of a highly conductive material such as copper (Cu). A recess (not shown) is formed on the surface of the electrode 21, and a contact 22 made of a highly conductive material is fixed to the recess so as to slightly protrude from the surface of the electrode 21. A linear slit (not shown) extending in the direction is formed. Around the lower part of the current-carrying shaft 2o, several layers (Tj
An annular iron core 23 is disposed overlapping the current-carrying shaft 2o (several layers) and surrounding the side surface of the current-carrying shaft 2o at a certain interval. Furthermore, an annular solenoid coil 24 is formed by applying an insulating wave crest around the iron core 23 and winding a thin copper wire having a suitable cross-sectional area. This annular solenoid coil 24 includes a cover 25 made of a thin low-conductivity material such as stainless steel, which is provided to protect the annular solenoid coil 24 from metal vapor flakes generated when an arc is ignited in a vacuum. It is fixed around the side surface of the current-carrying shaft 20 by a mounting plate 26 for fixing the annular solenoid coil, which is also made of a thin low-conductivity material. Further, on the opposite back side of the electrode 21, a thin copper wire having an appropriate cross-sectional area and also coated with insulation is wound inside near the outer periphery of the electrode 21 to form a solenoid coil 27. Solenoid coil fixing material 28 made of stainless steel etc.
Fixed by The solenoid coil 27 is
It is electrically connected to the annular solenoid coil 24 by a connecting wire 29 .

The contact 22 is formed from a melted or sintered contact material based on copper or silver (Ag).

Next, the operation of the vacuum interrupter configured as described above will be explained. When a short-circuit current flows through the current-carrying shaft 20, a strong magnetic field is generated around it in the circumferential direction.

Now, assuming that a current I (A) flows through the movable current-carrying shaft 20 and is cut off, the induced voltage vR induced in the annular solenoid coil 24 is equal to the number of turns per unit length of the annular solenoid coil 24 of the n1 iron core 23. If the magnetic permeability is μ and the small cross-sectional area of the annular solenoid coil 24 is a, then (1) can be easily obtained.
It is expressed by the formula.

When this vR is used as an induced voltage and the respective inductances of the annular solenoid coil 24 and the solenoid coil 27 are set to L2, a current i shown in equation (2) flows through the equivalent circuit shown in FIG. In Figure 2, 2
4A is the annular solenoid coil inductance, 27A is the solenoid coil inductance, 24B is the magnetic field generated when the current I flows through the annular solenoid coil 24, 27
B is the axial magnetic field generated by the solenoid coil 27;
8 is the resistance.

When this electric current 1fEi flows through the solenoid coil 27, a longitudinal magnetic field H shown in equation (3), which is synthesized by both the solenoid coils 24 and 27, is generated near the center of the fixed electrode and the movable electrode.

Here, b is the average radius of the annular solenoid coil 24°27, 2d is the center-to-center spacing of the solenoid coil 24°27,
N is the number of turns of each solenoid coil 24°27.

Therefore, an axial magnetic field H expressed by the above equation (3) is generated in the interelectrode space.

Next, we will consider the case where the method is applied to an actual vacuum interrupter. Now, 10 K is applied to the current-carrying shaft 20 with a diameter of 30 mm.
Considering the case where a breaking current of Ar, v, s (effective value 10 KA) is flowing, the average radius of the annular solenoid coil 24 is 25111 JI, and the inner radius r1 of the coil cross section (first
(shown in figure 1) - 20 pieces, outer radius "2 (shown in figure 1) = 3
0mm, center distance between both solenoid coils 24.27 (
Height) is 20mm, and the number of turns per unit length is 10.
If it is wound 00 times, the induced voltage vR
is vR-gv at maximum, but this can be freely changed by changing the number of turns of the iron core 23 and the annular solenoid coil 24.

Next, the axial magnetic flux density of the vertical magnetic field that minimizes the arc voltage varies depending on the abrasive material of the contact 22, but approximately I Q K
A r, m, ste 0. Assuming that the IT magnetic flux is required, a magnetic field of 8 x 10' AT/m is required by the solenoid coil 27, and if the center-to-center spacing of the solenoid coil 24.27 is 40 mm and the average radius is 40 mm, the required ampere turns are 9 x 103 AT. Become. Therefore, if the number of turns of the solenoid coil 27 is N-103, a current of 1-9 A is sufficient. Now, the inductance L1 of the annular solenoid coil 24 is equal to the inductance L1 of the annular solenoid coil 24.
The inner radius and outer radius of 4 are respectively rl as shown in Figure 1.
, r2, the magnetic permeability is μ (-relative magnetic permeability μs×magnetic permeability in vacuum), the number of turns is N1, and the coil height is h.

Based on this formula (4), specifically μ-320X4πx
lO (h/m), N-157 (times), h-20 (zz
), the inductance L1 is found to be 1. 77
(771H).

Next, if the inductance of the solenoid coil 27 is set to Nagaoka's coefficient of approximately 0.4, and the coil length is set to 1, then... (5) is obtained.

Therefore, if the total of both inductances is 130ηH1 resistance and about 50Ω, the total impedance is about 64Ω, so in order to apply about 10Ai to the solenoid coil 27, the induced voltage vR of about 700V is applied to the annular solenoid coil 24.
You can output it with . This is the annular solenoid coil 24
It can be freely changed by changing the number of turns, the cross sections U and y, and the core material.

Regarding the phase difference, if the resistance value is 50 Ω and the inductance is 130 mH, the generation of the vertical magnetic field will be delayed by about 2 m5 ec, but this is sufficient to expect the diffusion effect due to the vertical magnetic field of the vacuum arc.

When the vacuum interrupter is turned on, the energizing current is not shunted to the coil electrodes as in the case of conventional vertical magnetic field generating coil electrodes, but the current flowing through the energizing shaft 20 directly flows through the electrodes 21,
Since the current flows to the contact 20 and further to the opposing electrode, the impedance of the vacuum interrupter is sufficiently low, allowing large current to flow.

[Effects of the Invention] According to the present invention described above, on the back side opposite to the facing surfaces of the fixed electrode and the movable electrode, the wire is wound in the circumferential direction around the current-carrying shaft that supports the electrode. A solenoid that is supported and generates a vertical magnetic field, an annular iron core in which a thin plate of high magnetic permeability material is wound in several layers around the current-carrying shaft and close to the solenoid, and a conductive magnetic field around the iron core. The present invention includes an annular solenoid coil in which a required number of wires are wound and electrically connected to the solenoid coil.
An axial magnetic field proportional to the breaking current at the time of breaking occurs between the electrodes i
'7, since the vacuum arc can be sufficiently maintained in the diffusion mode, it is possible to provide a vacuum interrupter that has excellent interrupting performance and is capable of passing a large current with little temperature rise even when it is turned on.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing only the electrode portion of one embodiment of the vacuum interrupter of the present invention, and FIG. 4 is a cross-sectional view taken along the line ■-■ in FIG. 3 and viewed in the direction of the arrow. 20... Current-carrying shaft, 21... Electrode, 22... Contact,
23... Iron core, 24... Annular solenoid coil, 2
5... Cover, 26... Mounting plate for fixing the annular solenoid coil, 27... Solenoid coil, 28... Support material, 29... Connection wire. Applicant's agent Patent attorney Takehiko Suzue Figure 1 Figure 3 Figure 4

Claims (3)

[Claims] (1) each supported by a current-carrying shaft in a vacuum container;
In a vacuum interplater having fixed and movable electrodes that are arranged so as to be able to move toward and away from each other, on the back surface opposite to the opposing surface of the fixed electrode and the movable electrode, in the circumferential direction around the energizing axis. A solenoid for generating a vertical magnetic field is arranged and supported, an annular iron core in which thin plates of high magnetic permeability material are wound in multiple layers around the current-carrying shaft and close to the solenoid, and around this iron core. A vacuum interrupter comprising an annular solenoid coil having a required number of turns of conductive wire and electrically connected to the solenoid coil. (2) A vacuum interrupter according to claim 1, wherein contacts made of a sintered or melted material based on copper or silver are provided on the opposing front surfaces of the fixed and movable electrodes. (3) The vacuum interrupter according to claim 2, wherein linear slits extending in the radial direction are formed in the fixed and movable electrodes and the contacts arranged thereon.