JPS619113A - Electric insulator - 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 [Technical Field of the Invention] The present invention relates to a gas insulated switchgear in which an insulating gas is sealed, for example, as an electrical insulating device.

In particular, the present invention relates to improvements in solid insulators that support high voltage conductors trapped within the conduit.

[Prior art]

FIG. 1 is a diagram showing an example of a conduit in a conventional gas-insulated switchgear in a cross section of the upper half from the center line, and shows the same conical solid P! A plurality of grounding metals M/ are arranged in series, sandwiching the peripheral edge of the edge body. A plurality of high voltage conductors 3 are provided on the central axis of the ground metal l. The high voltage conductors 3 are connected through the center conductor. The solid insulator λ supports the center conductor DA at its center, and an insulating gas such as 5F, 8F, or G is sealed in each grounding container l. Note that the dotted line B in the figure exemplarily shows the lines of electric force that are assumed when a voltage is applied between the high voltage conductor 3 and the grounding container. It extends to

In the conventional gas insulated switchgear configured as described above, a so-called polarity reversal operation is performed to immediately reverse the voltage polarity of the high voltage conductor 3 for the purpose of power flow control during DC power transmission. In this case, the high voltage conductor 3 is operated with a negative polarity voltage, negative charges are accumulated on the surface of the solid insulator, and then the polarity is reversed and the high voltage conductor 3
If the polarity is immediately reversed to positive polarity, there is a drawback that the dielectric breakdown voltage decreases due to the influence of the residual charge caused by the accumulation.

This phenomenon will be explained in more detail as follows. That is, as shown in FIG. 2, which is an enlarged view of section A in FIG. 1, the surface of the high-voltage conductor 3 has been finished by ordinary machining, so that microprotrusions 3 are present in some parts. Electrons fly out from the tip of the microprotrusion 3 due to so-called field emission, and as these electrons receive force from the electric field, they end up along the lines of electric force B passing through the tip of the microprotrusion, as shown by arrow D. BFA gas will move in G space. These electrons are captured on the surface of the solid insulator interlinked with the lines of electric force B, accumulate as negative charges, and remain. Then, by reversing the polarity, the high voltage conductor 3
When the potential of the solid insulator quickly reverses from negative to positive, due to the presence of the negative charge remaining on the surface of the solid insulator, a higher voltage is generated on the surface of the solid insulator than in its absence. The electric field between the high-voltage conductor 3 and the conductor 3 increases locally, causing local breakdown of this portion, and in some cases, after the polarity is reversed, the entire circuit between the high-voltage conductor 3 and the grounding container l etc. is destroyed.

[Summary of the invention]

This invention was made for the purpose of eliminating the above-mentioned drawbacks, and by improving the shape of the insulator so that the lines of electric force from the conductor do not interlink with the surface of the insulator. An object of the present invention is to provide an electrical insulating device capable of suppressing the accumulation of charge on the substrate and preventing a decrease in dielectric breakdown voltage due to the accumulation of charge.

[Embodiments of the invention]

1@ Below, embodiments of this invention will be explained based on the drawings.
4 Ru. FIG. 3 is a cross-sectional view showing the upper half of the pipeline of a gas-insulated switchgear according to an embodiment of the present invention, and the same or corresponding parts as in FIGS. , and its explanation will be omitted.

The solid insulator 12, whose peripheral edge is fastened and fixedly supported by a flange /'a and whose center part is fixed to the center conductor, bulges out so that the center part becomes thicker, and is symmetrical about the center line C. It has a disc shape. The wall thickness tl of the peripheral edge of the solid insulator 1 is designed to have sufficient mechanical strength against the electromagnetic force when a short circuit current flows through the high voltage conductor 3 and the internal pressure of 8F & gas G. . The wall thickness tJ of the central portion of the solid insulator 1 is configured to be larger by the wall thickness tz, JL3O-3r%.

Here, the reason why it is set to be 3O-Jj% is based on the results of an experiment conducted by the inventors based on the experimental procedure shown below.

l) Grounded container; inner diameter ikOm J) Insulating gas: sF' = gas pressure 0 absda)
High voltage conductor applied voltage: DC negative polarity lθOkV5) Voltage application time: so minutes After applying the above voltage, the surface of each solid insulator corresponding to each sample was observed, and it was found that sample Accumulation of charges was observed on the entire conical concave side, which is the opposing surface of the high voltage conductor 3 interlinked with the line B. On the other hand, sample #
In J, only a small amount of charge accumulation on the surface was observed, and a large significant difference was observed between the two samples +, , and +2.

This occurs on the surface of the insulator of sample #a.

This indicates that there was only a very small portion interlinking with the line of electric force B from the high voltage conductor 3, and as shown in Figure 3, the line of electric force B from the high voltage conductor 3 was connected to the solid insulator. Be careful not to link with the surface of the l.

This is because a solid insulator is formed.

Figure 3 is a cross-sectional view showing the upper half of the gas insulated switchgear according to another embodiment of the present invention, in which the solid insulator l is parallel to the center line C and the center conductor is parallel to the center line C. It has a patented shape with a central axis. The wall thicknesses t and y of the solid insulator saw are.

This was determined based on the same experimental procedure as in the above example, and in this example as well, the electric force line B does not interlink with the surface of the solid insulator, and the same as in the above example. It is also possible to prevent charges from accumulating in the solid insulator 7.2 due to field emission.

In the above embodiments, the electrical insulating device is a gas insulated switchgear; however, the present invention is not limited to this, and any electrical device having a portion where electricity from a conductor intersects with the surface of an insulator may be used. Any configuration may be sufficient, and the same effects as in the above embodiment can be achieved.

〔Effect of the invention〕 .

As explained above, according to the electrical insulation device of the present invention,
Based on field emission, by improving the shape of the insulator so that the electric lines of force from the conductor do not interlink with the insulator surface.
Suppresses the accumulation of charge on the insulator.

This has the effect of preventing a decrease in dielectric breakdown voltage due to charge accumulation.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the upper half of a conventional gas insulated switchgear from the center line, and FIG. 4 is an enlarged view of section A in FIG. FIG. 3 is a cross-sectional view of the upper half of the gas insulated switchgear in one embodiment to which this invention is applied, and FIG. 1 is a sectional view of the gas insulated switchgear in another embodiment to which the present invention is applied It is a sectional view of half. 111・Grounding container (container), λ, l co・・Solid insulator (
Insulator), 3e/high voltage conductor (conductor), B6ko electric force lines. In each figure, the same reference numerals indicate the same or corresponding parts. I$1 figure, 2 figures, 3 figures

Claims (3)

[Claims] (1) A cylindrical container filled with an insulating gas, a conductor provided coaxially with the central axis of the container and to which a predetermined voltage is applied, and an edge attached to the container, In an electrical insulating device comprising an insulator whose center part supports the conductor, the insulator is formed such that a wall thickness of the insulator on the container side is not larger than a wall thickness on the conductor side. An electrical insulating device characterized by: (2) The thickness of the insulator on the conductor side is 30 mm thicker than the thickness on the container side.
-35% greater electrical insulation device according to claim 1. (3) The electrical insulation device according to claim 1, wherein the insulator has a flat plate shape in which the thickness on the conductor side and the thickness on the container side are equal.