JPS6338807B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vacuum shield breaker, and more particularly to a vacuum shield breaker in which a coil for generating an axial magnetic field perpendicular to the electrode surface is disposed behind each electrode.

In general, as shown in FIG. 1, a vacuum chamber disconnector is constructed by airtightly closing both ends of a cylindrical insulating tube 1 made of glass or ceramic with disk-shaped metal end plates 2 to form a vacuum vessel 3. A pair of electrodes 4 are introduced into the vacuum chamber 3 from the center of both metal end plates 2 so as to be able to approach and separate from each other via a pair of electrode rods 5. It is set up and configured.

However, the arc that occurs when a typical vacuum shield disconnector disconnects becomes extremely unstable due to the interaction between its own magnetic field and the magnetic field of the external circuit.
As it moves along the electrode surface, it is unevenly distributed around the electrode surface,
The electrode is locally heated and a large amount of metal vapor is released, resulting in a decrease in shear shear capacity.

In order to deal with this problem, as shown in FIG. This is a so-called vertical magnetic field electrode in which a coil 6 that generates a magnetic field (up and down in Figure 2) is installed, and the axial magnetic field generated by the coil 6 spreads the arc uniformly on the electrode surface to increase the shear capacity. The vacuum cutter is known.

However, in vacuum shield breakers using vertical magnetic field electrodes, the axial magnetic field generated by the coil 6 interlinks with the electrode rod 5, which is usually made of copper, resulting in eddy currents in the electrode rod 5. Since the magnetic field generated by the current acts to reduce the axial magnetic field, the shear capacity is reduced accordingly.

The present invention has been made in view of the above-mentioned problems, and its purpose is to reduce the eddy current generated in the electrode rod by improving the shape etc. of the electrode rod, thereby reducing the eddy current generated by the coil. An object of the present invention is to provide a vacuum shear breaker for a longitudinal magnetic field electrode that can reduce the loss of the axial magnetic field and effectively increase the shear breaker capacity.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings from FIG. 3 onwards. In the following description, the same reference numerals are given to constituent members having the same functions as those described above, and redundant explanation will be omitted.

FIG. 3 is a sectional view of the essential parts of the vacuum shield disconnector according to the present invention, in which a pair of electrode rods 5 made of copper are introduced into a vacuum container (not shown) so as to be able to approach and separate from each other.
A small diameter portion 5a is formed over a predetermined length at the inner end. The small diameter portion 5a is for reducing the linkage of the axial magnetic field generated by the coil 6 to reduce the generation of eddy current in the electrode rod 5, and the axial length L of the small diameter portion 5a is is at least the length of the dimension corresponding to 1/3 of the outer diameter D of the electrode 4 from the inner end (upper end in FIG. 3) of the electrode rod 5 corresponding to the middle part of the coil 6, and the outer diameter of the small diameter portion 5a. d
30 m/m or less, and a reinforcing pipe 7 made of stainless steel is fitted by brazing or the like into this small diameter portion 5a to increase mechanical strength and enable high voltage current to be applied and cut. It is worn.

In addition, in the small diameter portion 5a, the outer diameter of the electrode rod 5 is 30 m/
Of course, it is formed when the outer diameter of the electrode rod 5 is 30 m/m or less over the entire length. In addition, the reinforcing pipe 7 is
Even if the inner circumferential surface and the outer circumferential surface of the small diameter portion 5a are in close contact with each other, there is no problem even if there is a gap between both surfaces.

Here, if eddy current is generated due to a change in the outer diameter of the electrode rod 5 and the range of the outer diameter change, that is, a change in the axial length L of the small diameter portion 5a, in other words, due to a change in the shape of the electrode rod 5. Therefore, an experiment was conducted to examine the influence of the axial magnetic field generated from the coil 6. Figure 4 shows the experimental results. That is, in FIG. 4, the horizontal axis is the outer diameter d of the small diameter portion 5a of the electrode rod 5, and the vertical axis is the magnetic flux density at the center of the electrode surface, where the case where there is no electrode rod 5 is taken as 100%. , each curve A to D is
When the outer diameter of the electrode 4 is D and the axial length L of the small diameter portion 5a of the electrode rod 5, the A curve is such that L extends over the entire length of the electrode rod, the B curve is L>1/3D, and the C curve is L＞
The 1/2D and D curves show the results obtained by setting L>D, changing the outer diameter d of the small diameter portion 5a from 10 m/m to 60 m/m, and measuring the corresponding magnetic flux densities. Therefore, by making the length of the small diameter portion 5a at the inner end of the electrode rod 5 longer than the length corresponding to 1/3 of the outer diameter of the electrode, and making the outer diameter 30 m/m or less, It can be seen that the influence of eddy current can be reduced to 40% or less.

When the magnetic flux density decreases to 40% or more, the shearing performance decreases rapidly. That is, FIG. 5 is a characteristic curve showing the relationship between changes in magnetic flux density and shear current, with the horizontal axis representing the magnetic flux density and the vertical axis representing the shear current.

As a sample, curve C in Fig. 4, that is, L>1/2
When D is the outer diameter d of the small diameter part, 10φ,
The measurement results for 20φ, 30φ, and 40φ are shown, and the shear current value when d is 10φ is taken as 100%.

In addition, the magnetic flux density is 100% when there is no electrode rod, and it is impossible to cut it without the electrode rod, so the magnetic flux density is 80%.
Comparisons were made with the results at 100%.

As described above, the present invention provides a pair of electrodes in a vacuum container so as to be able to move toward and away from each other via a pair of electrode rods that are introduced into a vacuum container so as to be able to approach and move away from each other, and to generate an axial magnetic field at the back of each electrode. In a vacuum disconnector having a coil, the outer diameter of the length of the electrode rod from the middle part of the coil to the length corresponding to 1/3 of the outer diameter of the electrode or more is 30 m/m or less. Therefore, the interlinkage of the axial magnetic field with the electrode rod is reduced, so that the generation of eddy current can be significantly reduced. Therefore, the axial magnetic field can be effectively applied to the electrode surface, and the vacuum shielding capacity of the longitudinal magnetic field electrode and the disconnection capacity can be effectively increased.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of a general vacuum disconnector.
Fig. 2 is a schematic explanatory diagram of a vertical magnetic field electrode, Fig. 3 is a sectional view of a main part of a vacuum shield breaker according to the present invention, and Fig. 4 is an axial direction affected by the shape change of an electrode rod according to the present invention. Explanatory diagram showing the experimental results of the influence of magnetic field, No. 5
The figure is a characteristic curve diagram of shear current versus magnetic flux density. 3... Vacuum container, 4... Electrode, 5... Electrode rod,
5a...Small diameter portion, 6...Coil.

Claims (1)

[Claims] 1 A pair of electrodes are installed in a vacuum container so that they can be moved toward and away from each other via a pair of electrode rods that are introduced so that they can approach and separate from each other, and a coil that generates an axial magnetic field is arranged on the back of each electrode. The outer diameter of the electrode rod is 30
In a vacuum shield disconnector made of a material of 30 m/m or more, the inner end of the electrode rod is a small diameter part with an outer diameter of 30 m/m or less, and the axial length of the small diameter part is equal to the middle part of the coil. A vacuum shield breaker characterized by having a length equal to or more than 1/3 of the outer diameter of the electrode.