JPH08115624A - Conductor drawing out device - Google Patents

Abstract

PURPOSE: To relax, by simple constitution, electric field concentration caused in the low electric constant region of an insulated supporting body for supporting a conductor drawn out astride an insulation region having a different dielectric constant. CONSTITUTION: A bushing main body 9 is fixed, with a jaw part 10 nipped by metallic upper and lower part flanges 11 and 12, to support a conductor 5 penetrating through the middle part. The bushing main body 9 is composed of e.g. epoxy resin etc., and has 5.0-6.0 dielectric constants. The lower side of the lower part flange 12 is insulating oil having 2.2-2.0 dielectric constants, and the upper part of the upper part flange 11 is an insulating gas such as SF6 having a dielectric constant of about 1.0. Electric potential, between the earth electric potential of the upper part flange 11 and the high electric potential of the conductor 5, is apt to be sharply distributed in the insulating gas region having a dielectric constant lower than that of the bushing main body 9. Here, a distance, between the inner surface 13 of the upper part flange 11 and the bushing main body 9, is set longer than that, between the inner surface 13 of the lower part flange 12 and the bushing main body 9, to relax the concentration of electric field distribution.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used to insulate and support a conductor, which is used for connecting an electric device housed inside a tank and an external circuit, such as a bushing device, to the tank. The present invention relates to a conductor drawing device.

[0002]

2. Description of the Related Art In a bushing device, for example, as is well known, a conductor is passed through a bushing body made of epoxy resin or the like, and a flange portion provided on the outer periphery of the bushing body is held by a flange fixed to a tank. Thus, it is configured to be fixed and supported.

FIG. 6 shows a usage state of a bushing in a certain capacitor device, 1 is a tank filled with an insulating medium (for example, SF6 gas, air), and 2 is oil contained in the tank 1. An input capacitor, which is mounted on a pedestal 3 and supported by a support insulator 4. 5 is a conductor drawn from the oil-filled capacitor 2,
Reference numeral 6 is a bushing for the conductor 5, 7 is a connecting conductor for connecting the conductors 5 from the oil-filled capacitors 2 to each other, and 8 is an insulating spacer used to draw the connecting conductor 7 out of the tank 1.

FIG. 3 shows a conventional bushing 6. Conductor 5
Is supported so as to penetrate through the bushing body 9 made of, for example, an epoxy resin. A flange portion 10 is formed on the outer periphery of the bushing body 9, and the flange portion 10 has an upper flange 1 whose front and back surfaces are cylindrical in appearance.
1 and the lower flange 12 (both made of metal) are fixed so as to be sandwiched. The upper wall of the tank 1 may also serve as the lower flange 12. The upper flange 11 is fixed to the lower flange 12 so as to be tightened.

By the way, conventionally, the upper flange 11 and the lower flange 12 usually have the same inner diameter, so that the inner surfaces 13 and 14 of both flanges 11 and 12 are aligned along the vertical direction. Is configured to. On the other hand, below the lower flange 12 is insulating oil, and above the upper francy 11 is SF6 gas,
Insulating oil and SF6 gas have different dielectric constants.
As a specific example, the dielectric constant of insulating oil is about 2.2 to 2.0, and the dielectric constant of SF6 gas is about 1.0. The epoxy resin has a dielectric constant of 5.0 to 6.0.

By the way, in the bushing having such a structure, the high voltage of the conductor 5 is shared by the bushing body 9 between the high voltage of the conductor 5 and the flange having the ground potential.
In this case, it is known that the voltage sharing becomes large in the region where the dielectric constant is small. In this configuration example, the portion of SF6 gas between the bushing body 9 and the upper flange 11 has a larger voltage share than the portion of the insulating oil 9 between the bushing body 9 and the lower flange 12. In particular, it is known that the electric field value becomes extremely large at a portion (triple junction) where the upper flange 11, the bushing body 9, and the SF6 gas, which is an insulating medium having a low dielectric constant, coincide with each other, that is, the portion A in the example of the drawing. ing.

Such local concentration of the electric field is apt to cause dielectric breakdown at that portion, so that electric field relaxation is required. Therefore, conventionally, as shown in FIG. 4, a configuration has been proposed in which a metal fitting 15 having a ground potential is embedded in a portion extending from the inside of the bushing body 9 to the inside of the collar portion 10. However, constructing the bushing main body 9 by embedding the metal fitting 15 increases the manufacturing cost, and the embedding of the metal fitting 15 increases the risk of stress concentration and destruction. There's a problem.

[0008]

SUMMARY OF THE INVENTION The present invention provides a flange-like support from the front and back sides of a support, such as a collar, of an insulating support for conductors that are drawn across insulating regions of differing permittivity. When supporting so as to be found, it is an object to alleviate the electric field of the triple junction portion on the insulating region side having a low dielectric constant with a simple configuration.

[0009]

DISCLOSURE OF THE INVENTION According to the present invention, a distance between an insulating support and an inner surface of a flange on an insulating region side having a small dielectric constant, of the flanges for sandwiching the supporting portion of the insulating support from the front and back surfaces thereof. Is larger than the distance between the inner surface of the flange on the insulating region side having a large dielectric constant and the insulating support.

[0010]

By making the inner surfaces of the two flanges staggered, the equipotential lines of the triple junction portion of the farther away flange become sparse, and the electric field value at that portion decreases. In the present invention, the inner surface of the flange on the side of the insulating region having a small dielectric constant is located farther from the outer periphery of the insulating support than the inner surface of the flange on the side of the insulating region having a large dielectric constant, thereby forming a triple junction portion on the side of the insulating region having a small dielectric constant. The equipotential lines are sparse, and the electric field is relaxed accordingly.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG.
In addition, the same reference numerals as those in FIG. 3 indicate the same or corresponding portions. When the upper flange 11 is on the side of an insulating medium such as insulating gas and the lower flange 12 is on the side of insulating oil, the distance X between the inner surface 13 of the upper flange 11 and the bushing body 9 which is an insulating support is , Y is longer than the distance Y between the inner surface 14 of the lower flange 12 and the bushing body 9 (see FIG. 2).

As a result, the inner surface 13 of the upper flange 11 is separated from the inner surface 1 of the lower flange 12 from the conductor 5 having a high potential.
By moving away from 4, the electric field between the inner surface 13 of the upper flange 11 and the bushing body 9 becomes more relaxed than the electric field between the inner surface 14 of the lower flange 12 and the bushing body 9.

The results of the electric field analysis conducted by the present inventor are shown in Table 1.
(When an epoxy resin is used for the bushing body 9). This table shows the electric field values at the location A with respect to the respective distances X and Y (unit is mm), and is expressed as% with the electric field value when X = 15 and Y = 15 as 100.

[0014]

[Table 1]

As can be seen from Table 1, for sample numbers 1 and 2 in which the distances X and Y are the same, the electric field value decreases as the distances X and Y increase, but the values are sufficiently small. Don't On the other hand, Yangju, which only lengthened the distance X,
As will be understood from the sample numbers 3 and later, the electric field value is about 60%, which is sufficiently small. Further, as understood from this table, it is desirable to set the distance X to be twice or more the distance Y (sample number 4 or later), but the condition is determined by the restriction of the mounting place and the cost. .

FIG. 5 shows a state of electric field distribution between the bushing body 9 and the flange. FIG. 5 (b) shows a conventional configuration, in the vicinity of the inner surface 13 of the upper flange 11, particularly at the location A.
It is found that the electric field is concentrated in the vicinity of. On the other hand, (a) is according to the present invention, and the electric field is concentrated on the inner surface 14 of the lower flange 12, resulting in the upper flange 11
The electric field near the inner surface 13 becomes sparse. As shown in (c), when the inner surfaces of both flanges 11 and 12 are sufficiently distant from each other, the electric field becomes sparser than in the case of (b), but compared to the case of (a), the upper flange 11
Is denser than the electric field near the inner surface of.

When the insulating region is the insulating gas and the insulating oil as described above, the dielectric strength of the insulating material in the insulating gas easily deteriorates due to the adhesion of foreign matter. By increasing the distance between the inner surface of the flange 11 and the outer surface of the bushing body 9, the electric field on the creeping surface of the bushing body 9 is also reduced, and the degree of decrease in dielectric strength can be reduced. In other words, a high pure edge strength can be achieved with respect to adhesion of foreign matter.

Further, the internal pressure on the insulating gas side is generally higher than the internal pressure on the insulating oil side. In this case, a pressure based on the pressure difference is applied downward to the upper surface of the upper flange 11. This pressure is lower flange 1
However, since the inner surface 14 of the lower flange 12 is close to the bushing body 9, the lower flange 12 can sufficiently withstand this pressure.

Since it is not necessary for the upper flange 11 to receive this pressure, there is no problem even if the inner surface 13 of the upper flange 11 is kept away from the bushing body 9. Therefore, by forming the inner surface of the upper flange 11 away from each other, the material cost of the upper flange body 11 can be reduced.

[0020]

As described above, according to the present invention, a simple structure is provided in which the distance between the flange on the insulating region side having a small dielectric constant and the insulator supporting the conductor is increased.
The effect that the electric field on the side of the insulating region having a small dielectric constant can be relaxed is exhibited.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a partially enlarged sectional view of FIG.

FIG. 3 is a cross-sectional view showing a conventional example.

FIG. 4 is a partially enlarged sectional view of FIG.

FIG. 5 is a distribution diagram of an electric field.

FIG. 6 is a cross-sectional view of a capacitor device showing a usage example of a bushing.

[Explanation of symbols]

 5 Conductor 6 Bushing 9 Insulating Support (Bushing Main Body) 10 Support (Flange) 11 Upper Flange (Lower Permittivity Side Flange) 12 Lower Flange (Higher Permittivity Side Flange) 13 Inner Surface of Upper Flange 14 Lower Flange Inside

Claims (1)

[Claims] 1. A conductor drawing apparatus for supporting a supporting portion of an insulating support for a conductor drawn across an insulating region having a difference in dielectric constant so as to be sandwiched by flanges from the front and back surfaces thereof. Among the flanges that sandwich the support part of the support from the front and back surfaces, the distance between the inner surface of the flange on the insulating area side with a small dielectric constant and the insulating support is defined as the inner surface of the flange on the insulating area side with a large dielectric constant. A conductor drawing device which is larger than the distance from the insulating support.