JPH11126526A - Gas bushing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To optimize potential distribution in a lower part of a bushing, to eliminate the air shield of the lower part, and to improve the workability of transportation and installation. SOLUTION: This gas bushing comprises a main circuit conductor 4 which penetrates an insulator tube 1 in the axial direction to carry high voltage electric current; an earth shield 5 installed concentrically with the main circuit conductor 4 in the inside of the insulator tube 1; and a floating shield 8 installed concentrically with the main circuit conductor 4 inside the earth shield 5. The distance L1 from the center of the main circuit conductor 4 to the floating shield 8 in the radius direction, the distance L2 from the center of the main circuit conductor 4 to the earth shield 5 in the radius direction, and the distance L3 from the center of the main circuit conductor 4 to the inside of the insulator pipe 1 are set to satisfy the following: Ll:L2:L3=10:(11-13):(14-20).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas insulated switchgear for electric power, a gas circuit breaker or a gas transformer, and an optimization of an arrangement relationship and an area ratio of a grounding shield and a floating shield provided inside an insulator tube. Regarding the intended gas bushing.

[0002]

2. Description of the Related Art FIG. 3 is a structural view showing a conventional gas bushing, and FIG. 4 is an enlarged view showing a ground shield and a floating shield of FIG. As shown in FIGS. 3 and 4, a conventional gas bushing has an insulator tube 1 formed of a substantially conical porcelain, and insulator tubes 1a and 1b are attached to both ends of the insulator tube 1, respectively. An upper air shield 2 and a lower air shield 3 are attached to the upper and lower sides of the insulator tube 1 by insulator tube fittings 1a and 1b, respectively.

A main circuit conductor 4 for supplying a high voltage current is provided through the inside of the insulator tube 1 in the axial direction, and a ground shield 5 is arranged inside the insulator tube 2 concentrically with the main circuit conductor 4. Have been. At the upper and lower ends of the ground shield 5,
As shown in FIG. 4, a mounting seat 5a for mounting the rod-shaped insulator 6 is provided, and the ground shield 5 is mounted on the lower tank 7 by the mounting seat 5a.

Further, by fixing the mounting seat 8 a of the floating shield 8 to the rod-shaped insulator 6, the floating shield 8 is arranged concentrically with the main circuit conductor 4 inside the ground shield 5.

[0005] By appropriately selecting the dimensions, shape and arrangement of the lower air shield 3, the ground shield 5, the floating shield 8 and the insulator 1b, the insulator 1 near the lower portion of the conventional gas bushing insulator 1 is selected.
b, controlling the electric field at each part of the shields and along the surface of the insulator tube to obtain a withstand voltage performance as a gas bushing.

[0006]

However, in the above-mentioned conventional gas bushing, since the lower air shield 3 is provided, the lower air shield 3 is easily snow-covered in a snow-covered area. Since the insulation performance of the bushing is significantly reduced, a gas bushing without the lower air shield 3 is desired.

Further, the gas bushing provided with the lower air shield 3 is bulky and inconvenient for transportation, and has a problem of poor installation workability.

The present invention has been made in view of the above-mentioned circumstances, and has been made to provide a gas bushing having an excellent potential distribution at a lower portion of a bushing, eliminating a lower air shield, and being excellent in transportation and installation workability. is there.

[0009]

In order to achieve the above object, the present inventor has adopted a structure of a ground shield having a two-stage structure of a ground shield and a floating shield. Or, by optimizing the potential distribution of each shield, optimization of each electric field value can be obtained. The present invention has been completed based on the above findings.

That is, according to the first aspect of the present invention, a porcelain tube formed of a substantially conical porcelain and having porcelain fittings attached to both ends thereof, and a high-voltage current passing through the porcelain tube in the axial direction. A main circuit conductor, a ground shield disposed concentrically with the main circuit conductor inside the insulator tube, and a floating shield concentrically disposed with the main circuit conductor inside the ground shield. In the bushing, a radial distance L1 from the center of the main circuit conductor to the floating shield, a radial distance L2 from the center of the main circuit conductor to the ground shield, and a distance from the center of the main circuit conductor to the inside of the insulator tube. Satisfies the following relational expression.

[0011]

(Equation 4) The reason for limiting the ratio of the three in the relational expression will be described.

When the radial distance L2 from the center of the main circuit conductor to the ground shield is less than 11, the potential of the floating shield decreases and the insulation between the main circuit conductor and the floating shield is reduced. Due to the reduction in the diameter of the ground shield, the gap between the floating shield and the ground shield becomes too narrow, so that it is susceptible to manufacturing variations and the insulation performance is reduced.

If the radial distance L2 from the center of the main circuit conductor to the ground shield exceeds 13, the radius of the ground shield tip to alleviate the electric field at the tip of the ground shield cannot be maintained, or the insulator tube and the ground shield cannot be connected. The gap becomes narrower, manufacturing susceptibility becomes more susceptible, and insulation performance decreases.

When the distance L3 from the center of the main circuit conductor to the inside of the insulator tube is less than 14, the same problem occurs as when the radial distance L2 from the center of the main circuit conductor to the ground shield exceeds 13. .

When the distance L3 from the center of the main circuit conductor to the inside of the insulator exceeds 20, the gap between the inside of the insulator, the floating shield and the ground shield is enlarged, and the insulation between the gaps is reduced. In addition, since the insulation relaxing power of the floating shield and the ground shield with respect to the porcelain surface (outside) decreases, the insulation performance of the porcelain surface decreases. Further, since the gap between the floating shield and the main circuit conductor is narrowed, it is susceptible to manufacturing variations and the insulation performance is reduced.

However, by setting the ratio of the three as in the first aspect of the present invention, the electric field distribution of the ground shield and the floating shield is made uniform, and the creeping electric field of the insulator tube is determined from the gap between the insulator tube and the ground shield. Was confirmed to be able to be reduced.

According to a second aspect of the present invention, there is provided an insulator tube formed of a substantially conical porcelain and having insulator fittings attached to both ends thereof, and a main body which penetrates the insulator tube in the axial direction to supply a high voltage current. In a gas bushing comprising: a circuit conductor; a ground shield disposed concentrically with the main circuit conductor inside the insulator tube; and a floating shield disposed concentrically with the main circuit conductor inside the ground shield. The distance L4 from the tip of the insulator fitting attached to the large diameter end of the insulator tube to the ground shield end, and the distance L4 from the tip of the insulator fitting attached to the large diameter end of the insulator pipe to the end of the floating shield. The distance L5 satisfies the following relational expression.

[0018]

L4: L5 = 10: 12-20

The reason for limiting the ratio of these relational expressions will be described.

The ground shield has a 0% potential and the floating shield has a middle potential (15 to 25%), and equipotential lines for 0 to the middle potential are distributed between the ground shield and the floating shield.

When the distance L5 from the tip of the insulator fitting attached to the large-diameter end of the insulator to the end of the floating shield is less than 12, the equipotential line interval (gap, density) becomes smaller, and the electric field becomes smaller. , The insulation performance is reduced, and the floating shield reduces the rise in potential, thereby lowering the effect of the floating shield.

If the distance L5 from the tip of the insulator fitting attached to the large-diameter end of the insulator to the end of the floating shield exceeds 20, the electric field between the ground shield and the floating shield is reduced. However, the electric field at the upper end of the floating shield is increased, and the insulation performance is reduced.

However, it has been confirmed that the creeping electric field value of the porcelain tube having the weakest insulation can be reduced by setting the ratio between the two as in the second aspect of the present invention.

According to a third aspect of the present invention, there is provided a porcelain tube formed of a substantially conical porcelain and having porcelain fittings attached to both ends thereof, and a high-voltage current that passes through the porcelain tube in the axial direction. In a gas bushing comprising: a circuit conductor; a ground shield disposed concentrically with the main circuit conductor inside the insulator tube; and a floating shield disposed concentrically with the main circuit conductor inside the ground shield. An area S1 of the ground shield facing the floating shield and an area S2 of the floating shield facing the main circuit conductor satisfy the following relational expression.

[0025]

S1: S2 = 10: 15-25

The reason for limiting the ratio between the two in this relational expression will be described.

If the area S2 of the floating shield facing the main circuit conductor is less than 15, the potential of the floating shield decreases and the electric field between the ground shield and the floating shield is reduced, but the potential of the floating shield is reduced. The electric field from to 100% potential increases. Further, in conjunction with the decrease in the height of the floating shield, as a result, the electric field on the surface of the insulator tube (outside), which is not alleviated by the floating shield, increases, and the insulation performance as a bushing decreases.

When the area S2 of the floating shield facing the main circuit conductor exceeds 25, the potential of the floating shield rises, and the equipotential line interval (density) between the ground shield and the floating shield becomes narrow. As a result, the insulation performance deteriorates due to the electric field concentration.

However, it was confirmed that by setting the ratio between the two as in the third aspect of the invention, the electric field values of the main circuit conductor and the floating shield can be optimized.

According to a fourth aspect of the present invention, there is provided a porcelain tube formed of a substantially conical porcelain and having porcelain fittings attached to both ends thereof, and a main body for passing a high voltage current through the porcelain tube in the axial direction. In a gas bushing comprising: a circuit conductor; a ground shield disposed concentrically with the main circuit conductor inside the insulator tube; and a floating shield disposed concentrically with the main circuit conductor inside the ground shield. When the potential of the main circuit conductor is 100% and the potential of the ground shield is 0%, the potential of the floating shield is set to 15 to 25%.

The reason for limiting the potential of the floating shield will be described.

When the potential of the floating shield is less than 15%, the same problem occurs as when the area S2 where the floating shield faces the main circuit conductor is less than 15, as described above.

The potential of the floating shield is 2
If it exceeds 5%, the same problem occurs when the area S2 where the floating shield faces the main circuit conductor exceeds 25 as described above.

By setting the potential of the floating shield as in the fourth aspect of the present invention,
It has been confirmed that the electric field value of the floating shield can be optimized.

[0035]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a configuration diagram showing one embodiment of a gas bushing according to the present invention, and FIG. 2 is an enlarged view showing a ground shield and a floating shield of FIG. Parts that are the same as or correspond to those of the conventional configuration are described using the same reference numerals.

As shown in FIGS. 1 and 2, the gas bushing of the present embodiment is formed of a substantially conical porcelain, and has insulator tubes 1a and 1b attached to both ends thereof, respectively. A main circuit conductor 4 for passing a high voltage current therethrough in an axial direction, a cylindrical grounding shield 5 disposed concentrically with the main circuit conductor 4 inside the insulator tube 1, and a grounding shield 5 5 inside the main circuit conductor 4
And a floating shield 8 which is arranged concentrically and is formed in a cylindrical shape.

The floating shield 8 has an intermediate potential between the ground shield 5 and the main circuit conductor 4, and is fixed from the mounting seat 5 a of the ground shield 5 via the rod-shaped insulator 6. It is supported by the ground shield 5. The ground shield 5 is attached to the lower tank 7 by the attachment seat 5a.

In the present embodiment, the main circuit conductor 4
, A radial distance L1 from the center of the main circuit conductor 4 to the floating shield 8, a radial distance L2 from the center of the main circuit conductor 4 to the ground shield 5, and
The distance L3 to the inside is set so as to satisfy the following relational expression.

[0040]

(Equation 7)

By setting the dimensional ratio of the three as described above, it is possible to make the electric field distribution of the ground shield and the floating shield uniform and to reduce the creeping electric field of the insulator tube from the gap between the insulator tube and the ground shield. confirmed.

In this embodiment, the distance L4 from the tip of the insulator 1b attached to the large-diameter end of the insulator tube 1 to the end of the ground shield 5 and the length of the insulator 1b attached to the large-diameter end of the insulator 1 are determined. The distance L5 from the tip to the end of the floating shield 8 is set so as to satisfy the following relational expression.

[0043]

L4: L5 = 10: 12-20

The ground shield 5 has a 0% potential and the floating shield 8 has an intermediate potential (15 to 25%).
Equipotential lines for 0 to the intermediate potential are distributed.

It was confirmed that the creeping electric field value of the porcelain tube 1 having the weakest insulation was reduced by setting the dimensional ratio of the two as described above.

Further, in this embodiment, the ground shield 5
The area S1 facing the floating shield 8 and the area S2 facing the main circuit conductor 1 of the floating shield 8 are set so as to satisfy the following relational expression.

[0047]

## EQU9 ## S1: S2 = 10: 15-25

It has been confirmed that by setting the area ratio between the two, the electric field values of the main circuit conductor 1 and the floating shield 8 can be optimized.

Further, in this embodiment, when the potential of the main circuit conductor 1 is 100% and the potential of the ground shield 5 is 0%, the potential of the floating shield 8 is 15 to 25%.
%, It has been confirmed that the electric field value of the floating shield 8 can be optimized.

As a result, in FIG. 2, a potential distribution which is more effective in forming the gas bushing without the lower air shield in the vicinity of the portion A of the insulator tube 1 is formed.
It is possible to construct an electric field distribution equal to or higher than that of a conventional gas bushing with a lower air shield.

[0051]

As described above, according to the present invention,
By optimizing the dimension ratio and area ratio of the grounding shield and floating shield and the potential of the floating shield, it is possible to optimize each electric field value of the insulator surface, the insulator fitting, the grounding shield and the floating shield. A simple gas bushing without an air shield can be provided. As a result, not only is it effective for preventing snow cover in a snow-covered area, but also since there is no lower air shield, transportation and installation can be greatly simplified.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of a gas bushing according to the present invention.

FIG. 2 is an enlarged view showing a ground shield and a floating shield of FIG. 1;

FIG. 3 is a configuration diagram showing a conventional gas bushing.

FIG. 4 is an enlarged view showing a ground shield and a floating shield of FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulator tube 1a Insulator tube fitting 1b Insulator tube fitting 2 Upper air shield 3 Lower air shield 4 Main circuit conductor 5 Ground shield 5a Mounting seat 6 Bar insulator 7 Lower tank 8 Floating shield 8a Mounting seat

Claims (4)

[Claims] 1. A porcelain tube formed of substantially conical porcelain and having porcelain fittings attached to both ends thereof, a main circuit conductor which penetrates the porcelain in the axial direction and supplies a high voltage current, and In a gas bushing having a ground shield disposed concentrically with the main circuit conductor inside and a floating shield concentrically disposed with the main circuit conductor inside the ground shield, the center of the main circuit conductor A radial distance L1 from the main circuit conductor to the floating shield, a radial distance L2 from the center of the main circuit conductor to the ground shield, and a distance L3 from the center of the main circuit conductor to the inside of the insulator tube are represented by the following relational expressions. A gas bushing characterized by satisfying the following. (Equation 1) 2. A porcelain tube formed of a generally conical porcelain and having porcelain fittings attached to both ends thereof, a main circuit conductor which penetrates the porcelain in the axial direction and supplies a high voltage current, and In a gas bushing including a ground shield disposed concentrically with the main circuit conductor inside and a floating shield concentrically disposed with the main circuit conductor inside the ground shield, a large-diameter end of the insulator tube is provided. The distance L4 from the tip of the porcelain fitting attached to the end to the ground shield end and the distance L5 from the tip of the porcelain fitting attached to the large diameter end of the insulator to the end of the floating shield are as follows. A gas bushing characterized by satisfying the formula. L4: L5 = 10: 12-20 3. A porcelain tube formed of a substantially conical porcelain and having porcelain fittings attached to both ends thereof, a main circuit conductor which penetrates the porcelain in the axial direction and supplies a high-voltage current thereto, and In a gas bushing including a ground shield disposed concentrically with the main circuit conductor inside and a floating shield concentrically disposed with the main circuit conductor inside the ground shield, the floating of the ground shield An area S1 facing the shield,
A gas bushing wherein an area S2 of the floating shield facing the main circuit conductor satisfies the following relational expression. ## EQU3 ## S1: S2 = 10: 15-25 4. A porcelain tube formed of a substantially conical porcelain and having porcelain fittings attached to both ends thereof, a main circuit conductor which penetrates the porcelain in the axial direction and supplies a high voltage current thereto, and In a gas bushing including a ground shield disposed concentrically with the main circuit conductor inside and a floating shield concentrically disposed with the main circuit conductor inside the ground shield, a potential of the main circuit conductor Is 100% and the potential of the ground shield is 0%, the potential of the floating shield is 15 to 25.
Gas bushing characterized by setting to%.