JPS6131929B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improving the explosion protection of gas bushings.

In recent years, gas insulated equipment has come into widespread use because it can reduce the size of electrical stations, eliminate pollution, save labor, and improve safety. This gas-insulated equipment is often connected to air-insulated power transmission lines, and bushings are required here, and conventional oil-immersed paper capacitor type bushings and gas-insulated bushings are used. Oil-immersed paper capacitor bushings pose a risk of fire in the event of an accident, so gas bushings are increasingly being used. However, there are 3
Since the gas pressurized to about 4 kg/cm ² is filled for insulation purposes, flashovers occur on the surface of the insulator tube, and if the insulator tube breaks, fragments of the insulator tube will explode and scatter, causing damage to others. equipment, such as adjacent bushing insulators.

FIG. 1 shows an example of a conventional gas bushing.
1 is an insulator tube, and 2 is a conductor, which runs approximately through the central axis of the insulator tube 1. Reference numeral 3 denotes a ground electrode, which serves to alleviate the electric field in the lower part of the insulator tube 1 where the electric field is concentrated. Reference numeral 4 denotes an external electrode which, together with the grounding electrode 3, relieves the electric field in the lower part of the insulator tube 1. Reference numeral 5 denotes an upper electrode, which serves to relax the upper electric field. 6 is a mounting flange for the battery electrode 3, 7 is a container connected to gas insulated equipment (not shown), 8 is a sliding contact connected to gas insulated equipment (not shown), and 9 is a mounting flange for the conductor 2. A sliding contact 10 for escaping thermal expansion and contraction is an insulating spacer supporting the conductor 2.

The interior A of the insulator tube 1 of this bushing is filled with pressurized SF ₆ gas, similar to gas insulated equipment. The surface of the conductor 2 facing the ground electrode 3 has the largest electric field, and a gas pressure of 3 to 4 kg/cm ² (expressed in gauge pressure) is normally applied to this area, so in the unlikely event that the insulator tube 1 is damaged. There was a risk that the pieces would be scattered over a fairly large area. On the other hand, reducing the gas pressure of SF ₆ to about atmospheric pressure requires a large insulator tube, which is economically disadvantageous, and it is difficult to manufacture such a large insulator tube for ultra-high pressure applications.

The present invention has been made in view of the above, and provides a gas bushing that prevents explosive destruction and has excellent electrical performance.

The figures will be explained below. In Figure 2,
1 to 9 are the same as before. Reference numerals 11 and 12 denote partition walls made of a conical insulator that are fixed to the mounting flange 6 and protrude into the insulator tube 1, and close the space between the insulator tube 1 and the container 7 and support the conduit tube 2. 13,
Reference numeral 14 denotes an intermediate electrode, which improves potential distribution by capacitance between the conductor 2 and the ground electrode 3.
The partition walls 11 and 12 and the intermediate electrodes 13 and 14 are connected airtightly to each other, and the conductor 2 and the mounting flange 6 are also airtightly connected to each other, so that the space A inside the insulator tube 1 and the container 7 are connected airtightly.
It is separated from the interior B. Part B is filled with 3 to 4 kg of SF ₆ gas like general gas insulated equipment.
It is pressurized and filled to ^cm2 . Note that SF ₆ gas liquefies at high pressure, so it is generally not used in switchgear equipment.
Used ^below 15Kg/cm2. The part A inside the insulator tube 1 is brought to atmospheric pressure, that is, 0 kg/cm ² or a gas pressure close to this, and is filled with a gas that has better insulating performance than SF ₆ gas, such as C ₄ F ₆ . . C ₄ F ₆
has 2.2 times the dielectric strength of SF ₆ gas under the same pressure.

In the example of the structure shown in FIG. 2, the part with the highest electric field strength in the pressurized part B is the surface of the conductor 2 facing the intermediate electrode 14, but this part is made of pressurized SF ₆ gas. It has sufficient insulation strength. The part A where the electric field strength is large is
These are the portion indicated by m on the conductor 2, the portion n at the tip of the intermediate electrode 13, and the portion p at the tip of the electrode 3. These electric field strengths are less than half the strength of the SF ₆ portion pressurized to 3 to 4 Kg/cm ² , partly due to the effect of improving the potential distribution by the intermediate electrodes 13 and 14 . SF ₆ gas has a dielectric strength that is approximately 1/3 of that of 3Kg/cm ² at atmospheric pressure, and if a gas with a dielectric strength approximately 1.5 times that of SF ₆ gas at atmospheric pressure is used, the gas pressure at part A will be , atmospheric pressure is sufficient. Therefore,
If a gas such as C ₄ F ₆ , which has a dielectric strength 2.2 times that of SF ₆ gas, is filled at a pressure near atmospheric pressure, m,
It is possible to provide a bushing which has sufficient dielectric strength in terms of n and p and which does not cause explosion of the insulator tube 1.
By appropriately selecting the tip position of the intermediate electrode 13, the intermediate electrode 13 has the effect of equalizing and lowering the electric field strength on the surface of the porcelain tube 1 together with the ground electrode 3, and increasing the dielectric strength of the surface of the porcelain tube in the atmosphere.

Further, by configuring the partition walls 11 and 12 in a conical shape, the volume of the section A can be reduced and the amount of gas such as C ₄ F ₆ , which is more expensive than SF ₆ gas, can be reduced.

Note that the gas filled in part A contains C ₄ F ₆ ,
Gases such as C ₅ F ₈ and C ₆ F ₁₂ can also be used, and under the same pressure, they are 1.4 times stronger than SF ₆ gas, respectively.
It has a dielectric strength of 2.1 times and 2.3 times. It is also good to use a mixed gas of these gases and SF ₆ gas. For example, gas with 50% C ₄ F ₆ and 50% SF ₆ is SF ₆
It has a dielectric strength 1.75 times that of gas, so it can withstand use. Furthermore, the tendency of C ₄ F ₆ to liquefy at low temperatures is also reduced by lowering the partial pressure of C ₄ F ₆ , making it possible to apply it to locations with low temperatures. Of course, mixed gas also has great economic effects.

FIG. 3 shows another embodiment. In this example,
A large number of intermediate electrodes 15 are integrated with an insulator 16, that is, the intermediate electrodes 13 and 14 in FIG. The potted insulator 16 is sized and arranged to a useful size.
The partition wall 17 is constructed by solidifying the partition wall 17. Here, even if the intermediate electrode 15 of the partition wall 17 is omitted and the partition wall is made of only an insulating material such as FRP, it can be applied to a low-voltage bushing that allows a sufficiently large insulator tube to be obtained.

Furthermore, although the insulator tube will be a little larger, with the structure shown in Figure 1, the bushing part A and the gas insulated equipment part are airtightly separated using insulating spacers, and a gas with better insulating properties than SF ₆ gas is added to part A. may be filled to a pressure close to atmospheric pressure.

As described above, according to the present invention, it is possible to economically provide a gas bushing that is safe and has excellent insulation performance without any fear of explosion of the insulator or fire.

[Brief explanation of the drawing]

Figure 1 is a sectional view showing a conventional gas bushing.
FIG. 2 is a sectional view showing one embodiment of the invention, and FIG. 3 is a sectional view showing another embodiment of the invention. In the figure, 1 is an insulator, 2 is a conductor, 7 is a container, 11,
12 and 17 are partition walls. Note that the same reference numerals in each figure indicate the same or equivalent parts.

Claims (1)

[Scope of Claims] 1. A container filled with SF ₆ gas of 1 kg/cm ² (gauge pressure) or more, which is connected to an electrical device and has a conductor penetrating the inside of the insulated pipe, wherein the container and the insulated pipe are connected to each other. The space between them is closed with a partition wall, and the above-mentioned
0 insulating gas with higher insulating properties than SF ₆ gas
A gas bushing characterized in that the dielectric strength of the insulating gas in the porcelain tube is made equal to the dielectric strength of the SF ₆ gas in the container by filling with Kg/cm ² to 1 Kg/cm ² (gauge pressure). . 2. The gas bushing according to claim 1, wherein the inside of the insulator tube is filled with a mixed gas of SF ₆ gas and an insulating gas having higher insulation properties than the SF ₆ gas. 3. The gas bushing according to claim 1 or 2, wherein the partition wall is formed in a conical shape protruding into the insulator tube. 4. The gas bushing according to claim 1 or 2, wherein the partition wall has a structure in which the intermediate electrode is integrated with an insulator and has a conical shape protruding into the insulator tube.