JPS62278714A - Vacuum switch - 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 [Purpose of the invention] (Industrial application field) The present invention relates to an improvement in the structure of a vacuum switch.

(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, and as a result, they are now able to conduct and interrupt large currents. Currently, there are three main types of electrode structures used in the incluctor section of vacuum circuit breakers: contrast type, spiral type, and vertical magnetic field type (axial magnetic field type). Among these three types of electrode structures, contrast type and spiral type electrodes are
Referred to as an arc-driven type, the magnetic field created by the current flowing through the electrodes causes the arc poles of the vacuum arc generated when the electrodes are opened to rotate at high speed in the circumferential direction with a high current density, so that they do not stagnate in one spot on the electrode surface. In this way, the arc is extinguished when the current reaches zero point.

In this type of method, the arc voltage is high and the arc electrode with a large current density is generated, which causes severe damage to the contacts when interrupting large currents, dielectric breakdown re-ignition due to contact surface roughness, and contact surface damage. Thermal re-ignition caused by heat concentration in extremely rough areas places a limit on interrupting performance.

Figure 4 shows an example of a conventional vertical magnetic field type vacuum valve, in which the current flowing through the current-carrying shafts 1 and 2 is shunted in the circumferential direction by the coil electrodes 6 and 7 on the opposing surfaces of the electrodes 4.5. This is a method in which the axial magnetic field generated by this causes the arc to be ignited evenly over the electrode surface, and is interrupted when the current is reached. In this method, the arc voltage is low and the vacuum arc is evenly distributed and ignited on the electrode surface, reducing current density, suppressing storm damage to the contacts, and significantly improving breaking performance.

However, when the vacuum valve is turned on, the current is shunted from the current-carrying shafts 1 and 2 and always flows through the coil electrode 6°7 extending in the circumferential direction, so the impedance due to the resistance and inductance of the coil electrode 6°7 is large. The amount of heat generated is relatively large, which poses a problem especially when applying a large current at the time of turning on. In FIG. 4, 8.9 is a contact, 10 is an insulating tube, and 11.
12 is F, 12.13 is a bellows, and 14 is an arc shield.

(Problems to be Solved by the Invention) The above-mentioned conventional vacuum valve cannot be applied to circuit breakers that cut off large currents, and moreover, the problem is that the temperature rises high when energized when the valve is turned on. There is.

Therefore, the present invention is capable of interrupting large currents, and
The purpose of the present invention is to provide a vacuum switch that enables large current during official operation.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention is constructed as follows. That is, in a vacuum switch which is provided with a pair of electrodes supported by a fixed current-carrying shaft and a movable current-carrying shaft, respectively, and which are movable toward and away from each other, in a vacuum container having end plates provided at both ends of an insulating cylinder, the current-carrying shaft and A thin plate made of high magnetic permeability material is wound in multiple layers around an electrically connected main circuit conductor to form an iron core (I), and an insulated conductive wire is wound around this iron core to form an annular solenoid. A solenoid coil is provided around the insulating cylinder of the vacuum container or at both ends thereof, and the solenoid coil and the annular solenoid coil are electrically connected, and these are connected to the current-carrying shaft and the main circuit conductor. It is characterized by being electrically insulated.

(Function) With the above structure, an axial magnetic field proportional to the breaking current at the time of breaking can be obtained between the electrodes, and a sufficient vacuum arc can be maintained in the diffusion mode, resulting in excellent breaking performance.
Moreover, even if a large current is applied at the time of turning on, it is possible to carry out a large current with little temperature rise.

(Example) Hereinafter, an example of the vacuum switch of the present invention will be described in Figs.
This will be explained with reference to FIG. First, the overall configuration will be explained with reference to FIG. That is, a pair of fixed electrodes 22a and a movable electrode 22 are placed in a vacuum container configured by providing end plates 21a and 21b at both ends of an insulating cylinder 20, which can be freely brought into and out of contact with each other.
A pair of solenoid coils 23a, 23b are mounted on the side surface of the insulating cylinder 20 or on the end plates 21a, 21b at both ends, and a fixed current-carrying shaft 24a,
The movable energizing shaft 24b is the center of the arrangement.

Then, thin conductive wires such as copper are coated with insulation and wound around laminated cores 26a and 26b made of thin plates of high magnetic permeability material, which are wound around the fixed current-carrying shaft 24a, the movable current-carrying shaft 24b, and the main circuit conductors 25a and 25b, respectively. annular solenoid coil 27a
.

27b are electrically connected by connection lines 3Qa and 30b, respectively.

With this configuration, when a breaking current flows through the main circuit conductors 25a, 25b, the main circuit conductors 25a, 25b
Due to the magnetic field generated in the circumferential direction around b, an induced voltage is generated in the annular solenoid coils 26a and 26b, and the upper solenoid coil 1 23a electrically connected thereto
, 23 b A current flows and generates an axial magnetic field.

Therefore, the solenoid coil 23a.

23b is the electrode 22a at an interval twice the radius of the electrode 22a.

The space between 22b is the center of the arrangement. This is electrode 2
This is to generate a uniform circular magnetic field in the space between 2a and 22b.

Further, the molds 122a and 22b are provided with slits extending linearly in the radial direction, and the electrodes 22a are formed.

A cylindrical intermediate shield 28 made of a low-conductivity material surrounding the periphery of the intermediate shield 22b is square, and the intermediate shield 28 is provided with a thin slit 28a in the axial direction thereof, as shown in FIG.

For this reason, the fixed current-carrying shaft 24a and the movable current-carrying shaft 2
An axial magnetic field is generated in the space between the electrodes 22a and 22b when the electrodes are separated, without dividing the current flowing through the electrodes 4b.
°A large current can be cut off, and the current-carrying shaft 24 a when turned on,
The current flowing through 24b is directly connected to the electrode 2 from the main circuit conductor 25a without being shunted to the conventional coil electrode.
2a and 22b to the main circuit conductor 25b on the opposite side, heat generation is suppressed and large current can be passed. In FIG. 1, 29a and 29b are the electrodes 22a.

22b, respectively.

Next, the operation of the vacuum switch configured as described above will be explained. The short circuit current flows through the main circuit conductor 25a1 fixed current-carrying shaft 24a,
When flowing to the contact point 29a, a strong magnetic field is generated in the circumferential direction around the main circuit conductor 25a. Now, assuming that a current of I (A) flows through the contact 29b5 electrode 22b and the movable current-carrying shaft 24b and is interrupted, the annular solenoid coil 27
The voltage VR induced in a and 27b is the annular solenoid 2
7a.

The number of turns per unit length of 27b is n1 iron core 26a.

The magnetic permeability of 26b is μ, and the annular solenoid coils 27a, 2
If the cross-sectional area of 7b is a, then the following formula % Formula % Let this vR be the electromotive force, and the annular solenoid coil 27a,
27b and solenoid coil 23a.

When the inductance of 23b is respectively L2, and the resistance is R, the following current i flows through an equivalent circuit as shown in FIG.

As this current i flows through the solenoid coils 23a, 23b, the following magnetic field is generated near the center of the fixed electrode 22a5 and the movable electrode 22b, which are combined by the respective solenoid coils 23a, 23b. Here, the average radius of solenoid coils 23a and 23b is b1 solenoid coil 2
Assuming that the distance between the centers of 3a and 23b is 2d, and the number of turns of each is N, then an axial magnetic field H shown by the above equation (3) is generated in the space between the electric conductors 22a and 22b.

Next, a case where the present invention is applied to an actual vacuum valve will be considered. Since the solenoid coils 23a and 23b and the annular solenoid coils 27a and 27b are the same, only one side will be described here. Solenoid coil 23
The radius of a is 100mIR, solenoid coil 23a,
When the center distance d between the two 23b is 200 mm, the axial magnetic field near the center has a magnetic flux density of 4.44×10 iN, as shown by equation (3). Now 0.2
If a magnetic flux density of T is required, 1N is 4.5X1
04 AT and the solenoid coil 23a is wound 500 times, the current flowing here is 90A. Assuming that the annular solenoid coil 27H has a cross-sectional area a of 2N and is wound at a rate of 50 T/m per unit length around an iron core 26a made of sendust with a magnetic permeability of about 3×10 4 , the induced voltage peak value V 1 will be about 0.121°.

Now, if 10KAnIIls flows through the main circuit conductor 25a, vR will be 1.7KV. The inductance L1 of the annular solenoid coil 30 can be calculated using equation (4).

Here, μ-μsμ0 -3X104X4Xπ×10, N is the number of turns in the coil table, r2 is the outer radius of the coil, and 1 is the inner radius of the coil.From this, the inductance L1 is about several mH. The inductance L2 of the solenoid coil 23a is calculated using the Nagaoka coefficient KO, L2 −KOμ.yr b2 N2 /7 −
(5) Here, assuming Ko=0.4, J-0.05m
If calculated as follows, it will be approximately L2-0.1H. The resistance of the annular solenoid coil 27b and the solenoid coil 23a is determined by the number of turns of each coil and the cross-sectional area of the insulated copper wire used, and can be considered to be approximately several ohms. Therefore,
The current i in equation (2) flows approximately 1.7KV15-340A, assuming that the total impedance is 5Ω. Therefore, enough current can flow to generate a magnetic flux of 062T. Due to this axial magnetic field, the vacuum arc generated during interruption is sufficiently diffused.

Moreover, the current flowing at the time of turning on is not divided into the coil electrodes 6 and 7 and flows through the main circuit conductor 25a, unlike the fourth conventional vertical magnetic field generating coil electrode.

The current flowing through the vacuum valve 25b directly flows from the fixed current-carrying shaft 24a or the movable current-carrying shaft 24b through the electrode 22a or 22b to the opposite pole, so the impedance of the vacuum valve is sufficiently low and a large current can be passed.

〔Effect of the invention〕

7 According to the present invention described above, a vacuum container is provided with a pair of electrodes supported by a fixed current-carrying shaft and a movable current-carrying shaft, respectively, and which are movable toward and away from each other, in a vacuum container having end plates provided at both ends of an insulating cylinder. In a switch, an iron core is constructed by wrapping several layers of thin plates made of high magnetic permeability material around the main circuit conductor electrically connected to the current-carrying shaft, and an insulated conductive layer is placed around this iron core. The wire is wound to form a circular solenoid coil.
Further, solenoid coils are provided around the insulating cylinder of the vacuum container or on both ends thereof, and the solenoid coil and the annular solenoid coil are electrically connected, and these are electrically separated from the current-carrying shaft and the main circuit conductor. Since it is insulated, an axial magnetic field proportional to the breaking current can be obtained between the electrodes, and the vacuum arc can be sufficiently maintained in the diffusion mode, resulting in excellent breaking performance. It is possible to provide a vacuum switch that can conduct large current with little increase.

[Brief explanation of drawings]

': Figure 21 is a schematic f74 diagram showing only the main parts of an embodiment of the vacuum switch of the present invention, Figure 2 is a front view showing an example of the intermediate shield in Figure 1, and Figure 3 is the figure in Figure 1. FIG. 4 is a schematic configuration diagram showing an example of a conventional vertical magnetic field type vacuum valve. 20... Insulating cylinder, 21a, 21b... End plate, 22
a... Fixed electrode, 22b... Movable electrode, 23a. 23b... Solenoid coil, 24a... Fixed current-carrying shaft, 24b... Movable current-carrying shaft, 25a, 25b... Main circuit conductor, 26a, 26b-- Iron core, 27a, 27b
...Annular solenoid coil, 28...Intermediate shield, 28a...Slit, 29a, 29b-...Contact, 3
0a, 30b...Connection lines. Applicant's agent Patent attorney Takehiko Suzue Figure 1 Figure 2 Figure 3

Claims (4)

[Claims] (1) In a vacuum switch which is provided with a pair of electrodes supported by a fixed current-carrying shaft and a movable current-carrying shaft, respectively, and which are movable toward and away from each other, in a vacuum container having end plates provided at both ends of an insulating cylinder, the current-carrying shaft is An iron core is formed by wrapping multiple layers of thin plates made of high magnetic permeability material around the main circuit conductor electrically connected to the main circuit conductor, and an annular solenoid coil is formed by winding an insulated conductive wire around this iron core. In addition, solenoid coils are provided around the insulating cylinder of the vacuum container or on both ends thereof, and the solenoid coil and the annular solenoid coil are electrically connected, and these are electrically connected to the current-carrying shaft and the main circuit conductor. A vacuum switch characterized by being electrically insulated. (2) The solenoid coils attached to the periphery of the insulating cylinder of the vacuum vessel or at both ends thereof are arranged at intervals approximately twice the radius of the solenoid coils, and are uniformly arranged within the vacuum vessel corresponding to the midpoint between the two solenoid coils. 2. The vacuum switch according to claim 1, wherein an axial magnetic field is generated. (3) The vacuum switch according to claim 1, wherein a radial slit is provided in the pair of electrodes. (4) Claim 1, characterized in that an intermediate shield made of a low conductivity material is provided on the inner surface of the vacuum vessel at a certain distance from the electrode, and an axial slit is formed in this intermediate shield. Vacuum switch as described.