JPH07230731A - Gas insulated switchgear and gas insulated bushing - Google Patents

Abstract

PURPOSE:To facilitate manufacture of a gas insulation switchgear and contract an external shape by setting a non-equality coefficient of an electric field, between mutual conductors connected to electric equipment in an insulation gas sealed vessel or between the conductor and a ground potential, to a specific range. CONSTITUTION:Electric equipment is stored in a sealed vessel sealed with insulation gas, and an insulation bushing having a conductor, connected to this electric equipment, is provided and connected to a cable in the outside of the vessel. In this gas insulated switchgear, as the insulation bushing, a cone-shaped insulation layer 31 is formed in the periphery of a center conductor 30 by injecting an epoxy resin, to provide a ground layer 32 by conductive paint in the periphery of the insulation layer. Here is set a non-uniform coefficient of an electric field, between the conductor 30 and ground potential of the ground layer 32, to 3 to 11 range. Consequently, it is preferable to set the cone-shaped slope to 45 deg. and further ratio of its height H to external diameter D to 0.4 or less. In this way, the insulation bushing, increasing a withstand voltage value, facilitating work and contracting an external shape, can be obtained.

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 and a gas-insulated bushing used in the gas-insulated switchgear.

[0002]

2. Description of the Related Art An example of a side view of a conventional gas-insulated switchgear is shown in FIG. In FIG. 9, the inside of the box 1 whose outer periphery is surrounded by a mild steel plate is airtightly divided into a circuit breaker chamber 3 in the front and a busbar chamber 4 in the rear by a partition wall 2 provided vertically.

Of these, a vacuum circuit breaker 5 is provided in the circuit breaker chamber 3.
Is stored. The partition wall 2 has a pair of insulating spacers 6
Are pierced vertically. The main circuit conductor 7 protruding to the rear of the vacuum circuit breaker 5 is connected to the front portion of the insulating spacer 6. A disconnector 8A for three phases is attached to the center of the busbar chamber 4, and a current transformer 9A is attached to a front terminal of the disconnector 8A.
Via the connection conductor 10 to the rear portion of the upper insulating spacer 6.

A gas-insulated bushing is provided on the ceiling of the box 1.
11 are pierced for three phases, and this gas-insulated bushing 11
The lower terminal of is connected to the rear terminal of the disconnector 8A.
Also, on the rear surface of the lower part of the partition 2, the same rating as the disconnector 8A
The same type of disconnecting switch 8B is attached for three phases, and is connected to the rear terminal of the lower insulating spacer 6 by an L-shaped conductor 12 from above. The lower terminal of the disconnector 8B is connected to the current transformer 9B by the connecting conductor 13, and further connected by the connecting conductor 14 to the transformer 15 for the measuring instrument.
Connected to.

At the rear of the floor of the box body 1, a cable 16 is raised from the rear of the installation surface of the box body 1.
The cable head 17 is connected to the rear terminal of the current transformer 9B by a connecting conductor 18. At the top of the cable head 17,
A lightning arrester 19 is provided through the ceiling of the box body 1, and the lower end of this lightning arrester 18 can be brought into contact with or separated from the cable head 17. The busbar chamber 4 is filled with an insulating gas, and the insulating property of this insulating gas allows the gas-insulated switchgear to be downsized.

FIG. 10 shows the gas insulating bushing 11 among them.
FIG. In FIG. 10, the gas insulating bushing 11 is attached to the flange 20 on the ceiling of the box body 1 shown in FIG. 9, and the gas insulating bushing 11 divides the gas into upper air side and lower gas side of the flange 20. Has been done. In the gas insulating bushing 11, an insulating layer 22 cast with epoxy resin is formed on the outer periphery of a T-shaped central conductor 21. In addition, the O-ring 23 is attached to the mounting surface with the flange 20.
Is airtightly pressed.

A conductive paint is applied to the outer peripheral portion of the insulating layer 22 in FIG. 10 to form a ground layer 24. A through hole 25 for connecting a cable is formed on the air side of the gas insulating bushing 11. Further, on the gas side, a portion parallel to the central conductor 21 and a semicircular groove at the lower end of this portion are formed in the grounding layer 24 of the flange attachment portion, and a groove 26 having an annular shape in a cross-sectional view not shown is formed. ing. .

[0008]

As disclosed in FIG. 10 and Japanese Utility Model Laid-Open No. 64-38717, the shape of the conventional gas-insulated bushing on the gas chamber side is parallel to the center conductor at the flange mounting portion. A semi-spherical groove 26 is formed. this is,
The insulation characteristics of SF ₆ gas depend on the electric field, and in the case of atmospheric pressure, it is necessary to design the insulation with an allowable electric field strength of 8.9 kV / mm or less, so round the metal conductor end and the insulation creeping surface, and It is designed with an optimized shape by attaching a shield and relaxing the electric field.

However, in the case of designing with such an optimized shape, there are drawbacks that the machining of the casting die is complicated, the cost is high, and it is difficult to reduce the outer shape.
Therefore, an object of the present invention is to obtain a gas-insulated switchgear and an insulating bushing which can be easily manufactured and whose outer shape can be reduced.

[0010]

According to a first aspect of the present invention, an electric device is housed in a hermetically sealed container in which an insulating gas is sealed, and a conductor connected to the electric device is disposed in the gas insulation. The switchgear is characterized in that the inequality coefficient of the electric field between the conductors or between the conductor and the ground potential is set in the range of 3 to 11.

According to a second aspect of the present invention, in a gas-insulated switchgear in which an insulating bushing is provided through an outer wall of a hermetically sealed container in which an insulating gas is sealed, a center conductor of an inner end of the hermetically sealed container of the insulating bushing is provided. It is characterized in that the outer insulating layer has a conical shape with an inclination of 45 degrees and the inequality coefficient of the electric field between the inner end of the sealed container of the central conductor and the ground potential on the fixed side of the insulating bushing is 3 to 11.

Further, according to a third aspect of the present invention, in an insulating bushing that penetrates an outer wall of a hermetically sealed container in which an insulating gas is sealed and has a central conductor buried in an axial center, an inner end portion of the hermetically sealed container of the insulating bushing is provided. The insulating layer has a conical shape with an inclination of 45 degrees,
The ratio of the height to the outer diameter of this insulating layer was 0.4 or less, and a groove with a semicircular cross section was formed coaxially with the center conductor on the bottom side of the insulating layer, the end of which is continuous with the surface of the insulating bushing that is attached to the outer wall. It is characterized by

Further, the invention according to claim 4 is an insulating bushing in which a central conductor is embedded in an axial center by penetrating through a flange portion of an outer wall of a sealed container in which an insulating gas is sealed,
The insulating layer at the inner end of the sealed container of the insulating bushing has a conical shape with an inclination of 45 degrees, and the ratio of the thickness of the flange to the height of the insulating layer is
0.2, and on the bottom side of the insulating layer, a groove with a semicircular cross section is formed coaxially with the center conductor on the mounting surface of the insulating bushing to the outer wall, and the width of the groove and the thickness of the flange are the same. It is characterized by

[0014]

In the invention described in claim 1, when the inequality coefficient is set in the range of 3 to 11, post-dielectric breakdown is caused through corona discharge, so that the withstand voltage value increases. Further, in the invention according to claim 2, the insulating layer on the outer periphery of the central conductor at the inner end of the sealed container is formed into a conical shape with an inclination of 45 degrees, and between the inner end of the sealed container and the ground potential on the fixed side of the insulating bushing. By setting the inequality coefficient of the electric field to 3 to 11, the withstand voltage value is increased by the corona stabilizing effect.

Further, in the invention described in claim 3,
The insulating layer on the outer circumference of the central conductor at the inner end of the hermetically sealed container has a conical shape with an inclination of 45 degrees, and the ratio of the height to the outer diameter of this insulating layer is 0.4 or less. By providing the semicircular groove coaxially with the center conductor on the bottom side of the insulating layer, the withstand voltage value increases. .

Further, in the invention as set forth in claim 4, the insulating layer on the outer periphery of the central conductor at the inner end of the hermetically sealed container is formed into a conical shape having an inclination of 45 degrees, and the ratio of the thickness of the flange to the height of the insulating layer is made. By setting the width to 0.2 and making the width of the semicircular groove and the thickness of the flange the same, the withstand voltage value increases.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. The electrode shape used in the experiment is shown in FIG. A round-edge conductor 27 and a plate electrode 28 having a ground potential were used in SF ₆ gas, and the radius of curvature of the end portion of the round-edge conductor 27 and the insulating distance between the electrodes were changed. The pressure of the insulating gas is 0.10 MPa.

The experimental results of FIG. 1 are shown in FIG. In FIG. 2, solid line A is a corona starting electric field, B is an AC commercial frequency voltage breakdown electric field, and solid line C is an impulse breakdown electric field. When the inequality coefficient f is 3.2 or more, the AC commercial frequency voltage breakdown electric field is higher than the corona starting electric field. However, the inequality coefficient f is 1
At 0.7 or more, the AC commercial frequency voltage breakdown electric field is higher than the impulse breakdown electric field.

Generally, according to the standard of electrical equipment, impulse withstand voltage is higher than AC commercial withstand voltage. For example,
Rated voltage 7.2kV of "closed metal switchgear and control gear" of the Japan Electrical Manufacturers' Association standard (JEM1425-1987)
In the insulation class 6A, the AC commercial frequency withstand voltage is 22 kV and the impulse withstand voltage is 60 kV. Therefore, when the inequality coefficient f is larger than 10.7, it is difficult to use because the impulse breakdown electric field is low in terms of insulation enhancement. That is, in the usable range of the corona stabilizing action, the inequality coefficient f is 3.2 to 10.7.

When the end of the round-edge conductor 27 is simulated as a spherical electrode, the inequality coefficient f can be calculated by the following equation. f = {(r + a) / r} · 0.9 The above equation is the inequality coefficient of the sphere-to-plate electrode, r is the radius of curvature, and a is the distance between the electrodes. By shearing, r = 1 (m
In the case of m) and a = 10 (mm), the inequality coefficient f is 9.9. Therefore, when the inequality coefficient f is used in the range of 3.2 to 10.7, the conductor end portion may be chamfered. However, when the inequality coefficient f is 3.2 or less, the radius of curvature becomes 5 mm or more,
Machining is required. Such characteristics are effective in determining the insulation distance between the conductor end and the flange when the conductor is attached to the bushing. The gas pressure is 0.2M
The above characteristics show the same tendency in a relatively low range of Pa or less.

The metal conductor has been described above,
A similar tendency is obtained with an insulator. FIG. 3 shows the shape of the gas insulating bushing. In FIG. 3, an insulating layer 31 cast with epoxy resin is formed in a conical shape in the upper part around the center conductor 30, and the creeping surface of the insulating layer 31 is the center conductor 30.
45 degrees (that is, the angle of the conical top is 90 degrees)
Is formed at an angle of. A conductive paint is applied to the dotted line portion to form the ground layer 32.

FIG. 4 shows the insulating characteristics with respect to the height H of the insulating layer 31. The outer diameter D of the insulating layer 31 is fixed to 60 mm, and the insulating layer 31
When the height H of the insulating layer is changed, the ratio of the height H of the insulating layer to the outer diameter D becomes
Below 0.4, the flashover voltage improves as the height of the insulating layer 31 is reduced. This is because the electric field in the central conductor direction is high and the electric field in the creeping plane is low. Although the flashover voltage is increased even if it exceeds 0.4, it cannot be adopted in order to reduce the size because the insulating layer needs to be infinitely high. Therefore, the ratio of the height of the insulating layer to the outer diameter is
Below 0.4, the bushing has the groove 35 shown in FIG. When the ratio of the height of the insulating layer to the outer diameter exceeds 0.4, the groove 39 shown in FIG.
And the bushing is formed.

In FIG. 5, the height H and the diameter D of the insulating layer 34 are shown.
When the ratio is less than 0.4, the groove 35 having a semicircular cross section facing the central conductor 33 is coaxially formed in the lower part of the insulating layer 34 of the flange mounting portion. Further, in FIG. 5, a conductive paint is applied to a dotted line portion on the outer periphery, and a ground layer 36 is formed. Next, in FIG. 6, when the insulating height H1 and the diameter D1 are used in a ratio of more than 0.4, a groove 39 having a semicircular cross section having a portion parallel to the central conductor 37 is formed in the insulating layer 38 of the flange mounting portion. Are formed coaxially. Further, a conductive paint is applied to the dotted line portion as in FIG. 5, and a ground layer 40 is formed.

FIG. 7 shows the impulse flashover characteristic of the bushing when the height of the insulating layer is fixed to 50 mm and the thickness of the flange is changed. As shown in Fig. 7, if the thickness of the flange is changed, the ratio of the thickness of the flange to the insulation height becomes
The maximum value is 0.2.

FIG. 8 shows how the bushing is attached. In FIG. 8, a semi-spherical groove 43 facing the central conductor 41 is formed in the insulating layer at the mounting portion of the flange 45. In addition, a conductive paint is applied to the dotted line portion, and a ground layer 44 is formed. The bushing is attached to the flange 45, and the contact surface between the bushing and the flange 45 is an O-ring.
Closely attached at 46. The thickness of the flange 45 is the same height as the diameter of the hemispherical groove 43.

In the present invention, in the unequal electric field region, the corona stabilizing action can be utilized within the range of the inequality coefficient of 3.2 to 10.7, and the withstand voltage is increased. Also, the ratio of the height of the insulating layer to the outer diameter
With 0.4 as the boundary, below 0.4, a semi-spherical groove facing the central conductor is formed, and above 0.4, a semi-spherical groove parallel to the central conductor is formed to change the ground structure. Therefore, in terms of processing, these can be cast in two parts centering on the central conductor, and because they are easy to process, not only can they be easily manufactured, but they can also be reduced in size.

[0027]

As described above, according to the invention of claim 1,
In a gas-insulated switchgear in which electrical equipment is housed inside a sealed container filled with insulating gas and conductors connected to this electrical equipment are arranged, inequalities in electric field between conductors or between conductor and ground potential By setting the coefficient in the range of 3 to 11, dielectric breakdown occurs after corona discharge and the withstand voltage value is increased, so that an insulating bushing that is easy to process and that can be reduced in outer shape is obtained. be able to.

According to a second aspect of the present invention, in a gas-insulated switchgear in which an insulating bushing is provided through the outer wall of a hermetically sealed container in which an insulating gas is sealed, the center of the inner end of the hermetically sealed container of the insulating bushing is provided. The insulating layer on the outer circumference of the conductor has a conical shape with an inclination of 45 degrees, and the inequality coefficient of the electric field between the inner end of the sealed container of the central conductor and the ground potential on the fixed side of the insulating bushing is 3-11.
By so doing, the withstand voltage value is increased by the corona stabilizing action, so that it is possible to obtain an insulating bushing which is easy to process and whose outer shape can be reduced.

According to a third aspect of the present invention, in an insulating bushing having an axial center and a central conductor buried in the outer wall of the hermetically sealed container in which the insulating gas is sealed, the inner end of the hermetically sealed container of the insulating bushing is provided. The insulating layer of the part is conical with an inclination of 45 degrees, the ratio of the height of the insulating layer to the outer diameter is 0.4 or less, and the end is continuous with the bottom surface of the insulating layer and the mounting surface to the outer wall of the insulating bushing. Since the withstand voltage value was increased by forming the groove with a semicircular cross section coaxially with the center conductor, it is easy to process and
It is possible to obtain an insulating bushing whose outer shape can be reduced.

Further, according to the invention of claim 4,
In an insulating bushing that penetrates through the flange of the outer wall of the sealed container in which the insulating gas is filled and has a central conductor embedded in the shaft center, the insulating layer at the inner end of the sealed container of the insulating bushing has a conical shape with an inclination of 45 degrees. , The ratio of the thickness of the flange to the height of the insulating layer is 0.2, and a groove with a semicircular cross section is formed coaxially with the center conductor on the bottom side of the insulating layer, the end of which is continuous with the surface where the insulating bushing is attached to the outer wall. However, since the withstand voltage value was increased by making the width of the groove the same as the thickness of the flange, it is easy to process,
In addition, it is possible to obtain an insulating bushing whose outer shape can be reduced.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of a gas-insulated switchgear and a gas-insulated bushing of the present invention.

FIG. 2 is a graph showing the operation of the gas-insulated switchgear and the gas-insulated bushing of the present invention.

FIG. 3 is a partial cross-sectional view showing an embodiment of the gas-insulated switchgear and the gas-insulated bushing of the present invention.

FIG. 4 is a graph showing an operation of the gas-insulated switchgear and the gas-insulated bushing of the present invention, which is different from FIG.

FIG. 5 is a partial cross-sectional view showing another embodiment of the gas-insulated switchgear and the gas-insulated bushing of the present invention.

FIG. 6 is a partial cross-sectional view showing another embodiment of the gas insulated switchgear and the gas insulated bushing of the present invention.

FIG. 7 is a graph showing an operation of the gas-insulated switchgear and the gas-insulated switchgear according to the present invention, which is different from FIGS. 2 and 4.

FIG. 8 is a partial sectional view showing still another embodiment of the gas insulated switchgear and the gas insulated switchgear of the present invention.

FIG. 9 is a right side view showing an example of a conventional gas-insulated switchgear.

FIG. 10 is a sectional view showing an example of a conventional gas insulation bushing.

[Explanation of symbols]

1 ... Box body, 2 ... Partition wall, 3 ... Circuit breaker room, 4 ... Bus room, 5 ...
Vacuum circuit breaker, 6 ... Insulating spacer, 7 ... Main circuit conductor, 8
A, 8B ... Disconnector, 9A, 9B ... Current transformer, 10 ... Connection conductor, 11 ... Gas insulation bushing, 31, 34, 38 ... Insulation layer, 3
2, 36, 40 ... Ground layer.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masaru Miyagawa No. 1 Toshiba-cho, Fuchu-shi, Tokyo Toshiba Corporation Fuchu factory

Claims (4)

[Claims] 1. A gas-insulated switchgear in which an electric device is housed in a hermetically sealed container in which an insulating gas is sealed, and a conductor connected to the electric device is disposed, between the conductors or between the conductor and the ground. The inequality coefficient of the electric field between the electric potentials is 3 to 11
Gas-insulated switchgear characterized by having the range of 2. A gas-insulated switchgear in which an insulating bushing is provided through an outer wall of a hermetically sealed container in which an insulating gas is sealed. A gas insulated switchgear having an inclined conical shape, and an inequality coefficient of an electric field between an inner end of the sealed container of the central conductor and a ground potential on the fixed side of the insulating bushing is set to 3 to 11. 3. An insulating bushing in which an outer wall of a hermetically-sealed container in which an insulating gas is filled is penetrated and a central conductor is buried in an axial center, wherein an insulating layer at an inner end of the hermetically-sealed container of the insulating bushing is inclined at 45 degrees. A conical shape, the ratio of the height of the insulating layer to the outer diameter is 0.4 or less, and a groove having a semicircular cross section whose end portion is continuous with the mounting surface of the insulating bushing to the outer wall is formed on the bottom side of the insulating layer. An insulating bushing formed coaxially with the central conductor. 4. An insulating bushing in which a central conductor is embedded in an axial center through a flange portion of an outer wall of a hermetically sealed container in which an insulating gas is sealed, wherein an insulating layer at an inner end of the hermetically sealed container of the insulating bushing is 45 degrees. And the ratio of the thickness of the flange to the height of the insulating layer is 0.2, and the end of the insulating bushing is continuous with the bottom surface of the insulating layer. An insulating bushing in which a circular groove is formed coaxially with the central conductor, and the width of the groove and the thickness of the flange are the same.