JPH02309526A - Vacuum valve - Google Patents

Abstract

PURPOSE:To restrain high-frequency surge during operation effectively and realize a high-reliability, small-size and low-cost product by providing a cylindrical member with magnetism to be concentric to a conductive portion along an axial direction. CONSTITUTION:A fixed current conduction shaft 3 and a movable current conduction shaft 5 are provided with cylindrical structures 11a, 11b of strong- magnetism material. The structures 11a, 11b should be of conductive magnetic material such as iron but may be of high-resistance magnetic material such as ferrite. If such magnetic material is placed in a vacuum valve, the inductance of this part gets significantly big. Such big inductance has the operation of slackening sharp waves which occur between the contacts or between the electrodes 2 of the vacuum valve and rise quickly.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a vacuum circuit breaker, and in particular can suppress high frequency surges that occur when the vacuum circuit breaker is operated. The structure of the vacuum valve is as follows.

(Prior Art) In recent years, the voltage of circuits using vacuum circuit breakers has been increasing, and vacuum circuit breakers with rated voltages of 3.6 KV to 84 KV have been developed. Recently, a cubicle-type gas insulated switchgear has also been developed in which a vacuum valve is externally insulated with an insulating gas such as low-pressure SF6 gas within a rectangular grounded metal container.

It is a well-known fact that such operation of a vacuum circuit breaker generates high frequency surges inside the vacuum circuit breaker and in equipment connected to the vacuum circuit breaker. For example, when operating a vacuum circuit breaker, the maximum peak value of high frequency vibration of several MHI is
A surge voltage that is twice or more (2.0 pu or more) the peak value of the constant operating voltage may occur. There have been reports of cases where insulation breakdown accidents occurred in transformers and motors connected to vacuum circuit breakers due to this steep wave crest. Furthermore, these surges are induced into the grounding system of the vacuum circuit breaker, causing various radio interference and damage to the low voltage control circuit. Therefore, it is necessary to suppress the high frequency surge generated in the vacuum circuit breaker by some means.

In the SF6 gas circuit breaker, a resistor is connected to the tip of the circuit breaker's electrode using a method called resistance closing.

When another call occurs between the electrodes of the circuit breaker, this high-frequency current necessarily passes through the resistor, and the surge is immediately absorbed by this resistor and does not propagate.

In order to apply such a resistance closing method to a vacuum circuit breaker, it is necessary to use a structure in which the electrode for energizing and the electrode for interrupting the arc are separated, similar to a gas circuit breaker. If such a method is used, the electrode structure of the vacuum valve that constitutes the vacuum circuit breaker becomes complicated.

Furthermore, since the voltage between the poles immediately before the re-call occurs is applied to this resistor, a considerable insulation distance is required to prevent dielectric breakdown of the resistor due to this voltage. Furthermore, measures against vibrations during circuit breaker operation are also required. It is not a good idea to require such a complicated structure from a vacuum circuit breaker, which is characterized by its simple structure.

(Problems to be Solved by the Invention) As mentioned above, if a resistor injection method is used as a method of suppressing high frequency surges generated in a vacuum circuit breaker, the electrode structure becomes extremely complicated and the resistor itself requires a considerable insulation distance. As a result, the equipment itself becomes large and quite expensive.

The present invention has been made in view of the above circumstances, and can effectively suppress high frequency surges when operating a vacuum circuit breaker.
Furthermore, the purpose of the present invention is to provide a vacuum valve that is highly reliable, compact, and inexpensive.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a pair of electrodes that can be connected to and separated from an insulating container and a lid plate that closes openings at both ends of the insulating container within the vacuum container. One of the pair of electrodes is movably attached to one side of the cover plate via a bellows, and the vacuum valve is equipped with a movable current-carrying shaft and a fixed current-carrying shaft to which the pair of electrodes are attached. A magnetic member is arranged concentrically with respect to a conductive portion along the axial direction.

(Function) A magnetic member formed in a cylindrical shape is arranged so as to be concentric with the conductive part (formed by a fixed current-carrying shaft, a movable current-carrying shaft, and electrodes) along the axial direction. Therefore, the steep wave surge voltage generated between the electrodes when opening and closing the vacuum valve is suppressed, and damage to the connected transformer, electric motor, etc. can be prevented.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view showing one embodiment of the present invention.

In the figure, 1 is a contact, 2 is an electrode, and the current is interrupted at these parts. Reference numeral 3 denotes a fixed current-carrying shaft, which passes through the fixed side cover plate 4 and has its tip connected to one of the electrode sections. Reference numeral 5 denotes a movable current-carrying shaft, which is connected to the movable side cover plate 7 via a bellows 6, and whose tip is connected to the other side of the electrode 2. Reference numeral 8 denotes an intermediate shield that prevents the arc generated between the contacts 1 and 1 from directly contacting the inner surface of the insulating container 9 during the current breaker operation. This intermediate shield 8 is electrically insulated from both contacts 1 by being supported between two insulating containers 9. Reference numeral 10 denotes an end shield, which is provided to relax the electric field at the sealed portion of the insulating container 9.

Further, the above-described fixed current-carrying shaft 3 and movable current-carrying shaft 5 are provided with structures 11a and I formed in a cylindrical shape from a ferromagnetic material.
lb is installed. The structure 11a and fib are
Although it is assumed that a conductive magnetic material such as iron is used, a high resistance magnetic material such as ferrite may also be used.

Next, the operation of the embodiment having the above configuration (hereinafter referred to as the first embodiment) will be explained. Structure 11a.

The magnetic material forming 11b generally has a large relative magnetic permeability. For example, iron has μ=50H, and 50H in vacuum.
00 times the magnetic flux will be generated. Therefore, if such a magnetic material is installed inside the vacuum valve, the inductance of this part will become considerably large. For example, the inductance of iron with a length of 1 m is L=μOμ/2π・(dc+/di)...(1) where, μO: magnetic permeability in vacuum, μ=5[10G, do: magnetic material Outer diameter di: Inner diameter In () of magnetic material: Natural logarithm. Then, do = 10an, di =
In the case of 9.6 an, the inductance becomes a large value of 40.8 μH. This large inductance has the effect of dampening the rapid rise of steep waves generated between the contacts of the vacuum valve or between the electrodes 2.

This will be explained using the equivalent circuit shown in FIG.

That is, in the figure, 12 is the equivalent inductance of the ferromagnetic material given by equation (1), 13 is the characteristic impedance of the vacuum valve, and the current flowing through this equivalent resistance represents the surge propagating through the vacuum valve. .

Further, 14 indicates a source of a steep wave surge generated between the contacts 1 or between the electrodes 2 of the vacuum valve.

In such an equivalent circuit, consider a simple step wave as the surge waveform of the source 14, and assuming that the step wave is generated at t = 0, by solving the following circuit equation (2), the flow will flow through the equivalent resistor 13. Current i is determined.

Lφ (di/dt) +Ri =V...
(2) The solution to equation (2) that satisfies the initial conditions of 1=0 and f=0 is given by i=V/R・(1−e 1:t)−(3). Here, R represents the value of the equivalent resistance 13, and L represents the value of the equivalent inductance 12.

FIG. 3 shows this change in current i. In other words, the vertical axis represents the current (
When time (seconds) is plotted on the horizontal axis in A), the current i changes as shown by the curve ■.

In this way, by placing a magnetic material concentrically with the current-carrying shaft of the vacuum valve, the surge voltage generated by the vacuum valve can be significantly fluctuated, which prevents it from penetrating the transformer or motor connected to the vacuum valve. The surge voltage can be reduced.

Therefore, according to the first embodiment described above, by installing a ring-shaped structure made of a ferromagnetic material so as to surround the current-carrying shaft of a vacuum valve for a vacuum circuit breaker, the electrode of the vacuum valve is This vacuum valve is highly reliable, has low manufacturing costs, and has a small and simple configuration. Can be provided.

Note that the present invention is not limited to the first embodiment described above, and can be implemented in various modifications. That is, FIG. 4 shows structures 15a and 15b formed by winding a ferromagnetic material film in multiple layers around a current-carrying shaft, and a fixed current-carrying shaft 3 and a movable current-carrying shaft 5.
An example (hereinafter referred to as the second example) in which each of the two is installed is shown below. This second embodiment also provides the same effects as the first embodiment described above.

Further, FIG. 5 shows an embodiment (hereinafter referred to as a third embodiment) in which an intermediate shield 16 made of a magnetic material is installed between the insulating containers 9, 9 so as to surround the electrode 2. The other configurations are the same as in the first embodiment. This intermediate shield 16
For example, a multi-layered magnetic material such as an amorphous alloy containing iron as a main component is used, but other than this, a high-resistance magnetic material such as ferrite may also be used.
In addition, other magnetic materials with large μ such as permalloy (
μ = 10 [1,000), pure iron (μ = 1000.
000) etc., it is possible to make the cylindrical structure even smaller. This third embodiment (including one in which the shield 16 is made of various magnetic materials) also provides the same effects as the above-mentioned embodiments.

FIG. 6 shows an embodiment in which an intermediate shield 17 made of a magnetic material is installed between the insulating containers 9 and 9 so as to surround the electrode part.
Hereinafter, a fourth embodiment) will be shown.

The other configurations are the same as in the first embodiment. The intermediate shield 17 is made of an insulating material filled with magnetic powder, and the outer peripheral surface may be made of conductive metal. This fourth embodiment also provides the same effects as the above-described embodiments.

FIG. 7 shows an example (hereinafter referred to as
Embodiment 5) is shown. The other configurations are the same as in the first embodiment. This fifth embodiment also provides the same effects as each of the above-described embodiments.

[Effects of the Invention] As explained above, according to the present invention, the steep wave surge voltage generated between the electrodes is suppressed, the damage to equipment connected to the vacuum circuit breaker due to the surge voltage is prevented, and the reliability is improved. It is possible to provide a vacuum valve with a small and simple configuration, which has a low manufacturing cost.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the present invention, FIG. 2 is an equivalent circuit diagram showing the effect of the present invention, FIG. 3 is a step wave response waveform diagram showing the effect of the present invention, and FIG. 5 is a sectional view showing another embodiment of the invention, FIG. 6 is a sectional view showing another embodiment of the invention, and FIG. FIG. 7 is a sectional view showing still another embodiment of the present invention. 1... Contact 2... Electrode 3... Fixed energizing shaft 5... Movable energizing shaft 8, 16.17... Intermediate shield 9.11... Insulating container 11a, Ilb, 15a, 15b - ---
Structure (8733) Agent Patent Attorney Yoshiaki Inomata (
1 other person) Sheep 1 Zuden L (A) 3rd Kaya 411ffi $ 5 Zuhoki 61! I #7 Field

Claims (1)

[Claims] A pair of detachable electrodes is arranged in a vacuum container consisting of an insulating container and a lid plate that closes openings at both ends of the insulating container, and one of the pair of electrodes is connected to the lid plate through a bellows. In a vacuum valve that is movably attached to one of the electrodes and has a movable current-carrying shaft and a fixed current-carrying shaft to which the pair of electrodes are attached, a magnetic member formed in a cylindrical shape,
A vacuum valve characterized by being arranged concentrically with respect to a conductive part along the axial direction.