JPH10247444A - Gas insulation vacuum circuit breaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To downsize a gas insulation vacuum circuit breaker by enhancing withstand voltage without enlarging the radius of curvature of an electric field relaxation electrode. SOLUTION: In a gas insulation vacuum circuit breaker in which insulation gas is filled and which is provided with a vacuum valve equipped with an insulation vessel and electric field relieving electrodes the end portions of which are arranged at both ends of the insulation vessel apart by gas gap G, a quasi- uniform electric field is set to have 0.35 or more of utilization factor U which is obtained by the equation U=R/ 0.9(R+G)} based on the radius of curvature R of an electric field relieving electrode 16a outer peripheral face and the gas gap G, and a coating 23a made of insulation material is formed on one half or more of the outer peripheral face except a part opposite to the insulation vessel 13 on the electric field relaxation electrode 16a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas-insulated vacuum circuit breaker used for a gas-insulated switchgear, and more particularly to a gas-insulated vacuum circuit breaker that improves the electric field relaxation function and withstand voltage to reduce insulation.

[0002]

2. Description of the Related Art In recent years, in power receiving and distribution equipment such as a gas insulated switchgear, an insulating gas has been used to improve the dielectric strength and reduce the installation space. FIG. 6 is a side view showing this type of gas insulated switchgear and its peripheral configuration.
In this gas insulated switchgear, an insulating gas 2 such as SF ₆ gas is sealed inside a box 1 whose outer periphery is hermetically surrounded by a mild steel plate. A disconnector 3A is provided in the chamber 1a above the box body 1.
Is stored. In the lower chamber 1b of the box 1,
A gas-insulated vacuum circuit breaker 4 and a disconnector 3B having the same shape as the upper disconnector 3A are housed therein. The storage devices in the insulating gas are connected to each other by a main circuit conductor 6 fixed to the insulator 5. The main circuit conductor 6 is electrically connected to an external power cable 8 via a power receiving cable head 7 attached to the side of the box 1. In the power cable 8, power reception to the gas insulated switchgear and current supplied thereto are measured by the through-type current transformer 9. In addition, box 1
The main circuit conductors in the upper chamber 1a are electrically connected to adjacent boards vertically arranged in the drawing by an air-gas bushing 10 provided on the ceiling of the box 1.

[0003] In such a gas insulated switchgear, the breakdown voltage of the insulating gas 2 exhibits a strong electric field dependence in each of the storage devices, so that appropriate electric field relaxation is performed and the withstand voltage is maintained. For example, as shown in FIG. 7, the electric field relaxation structure of the gas insulated vacuum circuit breaker 4 has an electric field relaxation structure having a large curvature up to a position overlapping with the insulating cylinder 13 in order to reduce the electric field of the sealing electrode 12 of the vacuum valve 11. The electrode 14 is attached by a bolt 15. Such a method of relaxing the electric field is disclosed in, for example, Japanese Utility Model Publication No. 1-15071, in which an electric field relaxing electrode 14 having a diameter larger than the diameter of the vacuum valve 11 is used. In the electric field relaxing electrode 14, the starting point of the outer peripheral surface having a radius of curvature is a surface in contact with the insulating cylinder 13. The outer peripheral surface is classified into curved surfaces having different radii of curvature in the pole direction 14A and the interphase direction 14B, and the curved surfaces are formed continuously. As a result, the electric field relaxing electrode 14 alone is used to reduce the electric field.

[0004]

However, in the above-mentioned gas-insulated vacuum circuit breaker, the radius of curvature of the electric field relaxing electrode 14 is increased to reduce the electric field and improve the withstand voltage. There is a problem of increasing the size.

That is, from the viewpoint of electric field relaxation, even if the radius of curvature of the electric field relaxation electrode 14 is increased to shorten the gas gap, the size of the electric field relaxation electrode 14 itself is increased.
There is a problem that the arrangement of three phases results in an increase in size. That is, there is a limit to downsizing based on electric field relaxation with such a large radius of curvature. It also goes against the recent trend of shrinking.

The present invention has been made in view of the above circumstances, and provides a gas-insulated vacuum circuit breaker which can improve withstand voltage without increasing the radius of curvature of the electric field relaxing electrode and can be reduced in size. The purpose is to:

[0007]

According to a first aspect of the present invention, there is provided an electric field relaxing electrode in which an insulating gas is sealed, and an insulating container and an end provided at both ends of the insulating container with a gas gap G therebetween. A gas-insulated vacuum circuit breaker provided with a vacuum valve having a radius of curvature R of the outer peripheral surface of the electric field relaxing electrode.
The electric field utilization factor U obtained by the following equation based on the gas gap G is defined as a quasi-equivalent electric field of U = 0.35 or more. This is a gas-insulated vacuum circuit breaker in which a coating made of an insulating material is formed in at least half of the region.

U = R / {0.9 (R + G)} According to a second aspect of the present invention, in the gas insulated vacuum circuit breaker according to the first aspect, the coating is substantially 2
This is a gas-insulated vacuum circuit breaker having a thickness of 5 μm and made of an insulating material made of Teflon resin or epoxy resin.

Further, the invention corresponding to claim 3 is a vacuum valve in which an insulating gas is sealed, and which has an insulating container and an electric field relaxing electrode whose ends are arranged at both ends of the insulating container with a gas gap G therebetween. In the gas-insulated vacuum circuit breaker provided with the above, the electric field utilization factor U obtained by the following equation based on the radius of curvature R of the outer peripheral surface of the electric field relaxation electrode and the gas gap G is represented by U = 0.26 or less. It is a gas insulated vacuum circuit breaker with an electric field.

U = R / {0.9 (R + G)} According to a fourth aspect of the present invention, an insulating gas is filled,
A gas-insulated vacuum circuit breaker comprising a vacuum valve having an insulating container and an electric-field mitigating electrode whose ends are disposed at both ends of the insulating container separated by a gas gap G, wherein the vacuum valve is connected to a movable electrode of the vacuum valve; An insulating operation member formed so as to be able to advance and retreat in a direction substantially perpendicular to the axial direction of the vacuum valve, and an insulating operation member disposed opposite to the insulating operation rod in the axial direction, and a substantially U-shaped portion opposing the insulating operation member. A gas-insulated vacuum circuit breaker having a U-shaped concave portion and a support insulator for fixing the vacuum valve.

Further, according to a fifth aspect of the present invention, in the gas insulated vacuum circuit breaker according to the fourth aspect, the support insulator has a substantially elliptical cross-sectional shape and extends in the axial direction of the vacuum valve. First and second embedded electrodes embedded in parallel with each other, the first and second embedded electrodes having a substantially elliptical cross-sectional shape, and embedded so as to face the insulating operating rod via the first and second embedded electrodes. A gas-insulated vacuum circuit breaker provided with a third embedded electrode.

According to a sixth aspect of the present invention, in the gas insulated vacuum circuit breaker according to the fourth or fifth aspect, an electrode having an outer diameter larger than the outer diameter of the electric field relaxing electrode is embedded. A gas-insulated vacuum circuit breaker having a second supporting insulator for fixing the vacuum valve in rare cases.

According to a seventh aspect of the present invention, in the gas insulated vacuum circuit breaker according to the first aspect, the vacuum valve is fixed so as to have a relative dielectric constant higher than a relative dielectric constant of the insulating material. It is a gas insulated vacuum circuit breaker with a supporting insulator. (Operation) Therefore, the invention corresponding to claim 1 takes the above-mentioned means, and in a quasi-equivalent electric field having a large electric field utilization factor, a film made of an insulating material is formed on the electrode surface to withstand voltage. Characteristics can be improved. This coating suppresses the electric field strength by smoothing the unevenness of the electrode surface,
It is also assumed that electron emission is suppressed.

For this reason, the withstand voltage can be improved without increasing the radius of curvature of the electric field relaxing electrode, so that the radius of curvature can be reduced and the electric field relaxing electrode can be reduced, and the insulation between phases of the vacuum circuit breaker and between the ground can be achieved. The distance can be shortened, so that downsizing and downsizing can be achieved.

According to a second aspect of the present invention, since the film has a thickness of about 25 μm and is made of a Teflon resin or an epoxy resin, the action corresponding to the first aspect is easily and reliably achieved. Can be.

Further, according to the present invention, in the case of an uneven electric field having a small electric field utilization factor, for example, the end of the electric field relaxing electrode is provided on the insulating cylinder by separating it from the insulating cylinder of the vacuum valve by several mm. The electric field relaxing action by the synergistic effect with the provided electrode works to improve the withstand voltage.

According to a fourth aspect of the present invention, a support insulator for fixing a vacuum valve is formed in a U-shape, and an insulating operation member for opening and closing the vacuum valve is provided in the U-shaped opening, thereby forming a U-shape. By disposing an insulator made of the same insulating material in the opening, the disturbance of the electric field can be reduced, and the withstand voltage can be improved. Further, the space for the support insulator and the insulating operation can be reduced, and the overall shape can be reduced.

Further, according to a fifth aspect of the present invention, since the embedded electrode is divided into a plurality of parts, the volume of the metal to be embedded can be reduced so that the temperature of the metal mold can be quickly raised at the time of molding, and the adhesion to the insulating resin can be improved. By improving the properties, it is difficult to generate defects such as voids and peeling, and good insulation characteristics can be realized. Further, since each of the divided embedded electrodes can be apparently made a large electrode, the electric field of a supported object such as a vacuum valve fixed to the supporting insulator can be reduced.

According to a sixth aspect of the present invention, since the supporting insulator has an electrode having an outer diameter larger than the outer diameter of the electric field relaxation electrode, the equipotential lines near the electric field relaxation electrode are expanded to increase the electric field. Since the relaxation can be achieved, the radius of curvature of the electric field relaxing electrode can be reduced, and the shape of the electric field relaxing electrode can be reduced.

Further, in the invention according to claim 7, since the supporting insulator has a higher relative permittivity than the insulating material of the coating, the equipotential lines in the region along the supporting insulator are expanded to reduce the electric field. Therefore, the radius of curvature of the electric field relaxing electrode can be reduced, and the shape of the electric field relaxing electrode can be reduced.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a side view showing the internal configuration of a gas-insulated vacuum circuit breaker according to an embodiment of the present invention. The same parts as those in FIG. 7 are denoted by the same reference numerals, and detailed description thereof will be omitted. Is described only.

That is, the present embodiment is intended to realize electric field relaxation without increasing the radius of curvature of the electric field relaxation electrode, and has the following structure. In FIG. 1, electric field relaxation electrodes 16a and 16b are provided above and below the vacuum valve 11 for both electric field relaxation and conduction. The electric field relaxing electrodes 16a and 16b are fixed to each other via an insulating support plate 17 parallel to the axial direction of the vacuum valve.
Each support insulator 18a, 18 perpendicular to the axial direction of the vacuum valve
It is supported and fixed to the flange 19 via b.

A Russell mechanism 20 for opening and closing a movable electrode (not shown) in the vacuum valve 11 is provided inside the lower electric field relaxing electrode 16b.
Operation insulator 21 connected to the lower support insulator 18b
And are arranged in parallel. The insulation operation member 21 is connected to the operation mechanism 22 on the air side.

On the other hand, a coating 23a made of an insulating material such as Teflon resin or epoxy resin is formed on the upper surface of the upper electric field relaxing electrode 16a except for the surface facing the vacuum valve 11. The insulation thickness of the coating is several tens of μm, and is approximately 25 μm here. Similarly, a coating 23b is formed on a lower side of the lower electric field relaxation electrode 16b except for a surface facing the vacuum valve 11. That is, as shown in the enlarged view of FIG. 2, the electric field relaxing electrode on which the coatings 23a and 23b are formed is opposed to the insulating cylinder via the gas gap G, has a large radius of curvature, and has a high electric field utilization rate. And a quasi-equal electric field with a large value can be realized. The relative permittivity of the insulating material of the coating is smaller than the relative permittivity of the support insulator.

More specifically, the electric field relaxing electrode 16a is fixed by bolts 15, and its lower surface is a base without a coating or the like. The end of the electric field relaxing electrode 16a extends to the vicinity of the electrode part 24 connecting the sealing electrode 12 of the vacuum valve 11 and the insulating tube 13, and the upper end where the gap length G is maintained at several mm from the end of the insulating tube 13. It is located in. Therefore, in the lower part of the electric field relaxing electrode 16a (or on the side facing the insulating cylinder), an uneven electric field having an acute angle at the end is obtained.

As shown in FIG. 3, the support insulator 18b has a coaxial U-shaped opening 18c opposed to the insulating operation member 21. As shown in FIG. That is, the opening 18
Insulating operation members 21 are arranged in parallel along c. The gap between the insulating member 21 and the opening 18c is about 10 mm or more.
And an appropriate value that does not cause partial discharge. In addition, each of the embedded metal fittings 25a, 25b, 25
c is provided on each side except the opening 18c.

As shown in FIG. 4, the upper supporting insulator 18a is connected to the electrode 2 connected to the end of the electric field relaxing electrode 16a.
7 are embedded, and the electrode 27 reduces
6a is fixedly supported. Here, the support insulator 18
a that the diameter φ1 of the electrode 27 in FIG. 2a and the diameter φ2 of the electrode 16a for relaxing the electric field satisfy the relationship of φ1> φ2,
This is preferable from the viewpoint of electric field relaxation due to expansion of.

Next, the operation of the gas insulated vacuum circuit breaker configured as described above will be described. In addition, since each structure independently realizes electric field relaxation, the operation will be described separately for each structure. (Electrical Relaxation by Coating) FIG. 5 is a voltage characteristic diagram showing the result of investigation of the relationship between the breakdown (impulse flashover) voltage and the presence or absence of the coating while changing the radius of curvature. The characteristics of the black marks are as follows: a radius of curvature R = 40 mm;
The breakdown voltage of the electric field relaxing electrodes 16a and 14 arranged at m is compared for the presence or absence of the coating 23a. The characteristics indicated by white marks are the electric field relaxing electrodes 16a,
14 has a radius of curvature R = 3 mm. Here, in the case of the former R = 40 mm, the quasi-uniform electric field is obtained with the electric field utilization ratio U = 0.88, and in the case of the latter R = 3 mm, the electric field utilization ratio U =
An uneven electric field is 0.26. Note that an approximate value of the electric field utilization factor U can be obtained by the following equation.

Electric field utilization factor U = R / {0.9 (R + G)} where R: radius of curvature of the electrode, G: gas gap length. From the figure, in the quasi-equivalent electric field, when the electrode has the coating 23a,
The breakdown voltage is increased by about 25% as compared with the bare electrode. On the other hand, in the uneven electric field, the breakdown voltage of the electrode having the coating 23a hardly increases. In the electric field relaxing electrode 16a shown in FIG. 2, when the radius of curvature R was 30 mm, the gas gap G was 65 mm, and the electric field utilization factor U was 0.35, the breakdown voltage could be increased by about 10%. That is, in proportion to the electric field utilization rate U (or as the electric field becomes equal),
Since the effect of the coating 23a appears, it can be said that the breakdown voltage can be increased by using the coating 23a. Specifically, the coating 23a
Is presumed to have the effect of smoothing the unevenness of the electrode surface, suppressing the electric field strength and suppressing the electron emission from the electrode. For this reason, the radius of curvature R of the electric field relaxation electrode 16 can be reduced, and the gas gap G between the phases and the ground can be reduced, so that the single shape of the electric field relaxation electrode 16a can be reduced and the overall shape of the gas insulated vacuum circuit breaker can be reduced. The size can be reduced. If it is difficult to form the film 23 in about half of the electric field relaxation electrode 16 in the formation process, the film 23 may be provided on the entire surface of the electric field relaxation electrode 16.

Here, the end of the electric field relaxing electrode 16a is
Although a non-uniform electric field is formed by itself, the electric field can be reduced as a whole by the combination with the vacuum valve 11 and the synergistic effect with the electrode 24 coupled to the insulating cylinder 13. This electric field relaxation is performed by the insulating cylinder 13 and the electric field relaxation electrode 1.
It was greatly affected by the gas gap length G with the end of 6a. According to the experiment, when the gas gap G was about 2 mm, there was no breakage from the gas gap portion. The case where the gas gap G cannot be formed and wrapped with the insulating cylinder 13 results in the lowest breakdown voltage. The upper electrode 16a for relaxing the electric field
Although the configuration has been described as an example, the same configuration may be applied to the lower electric field relaxing electrode 16b. (Electrification alleviation by embedded metal fittings and the like) Since the embedded metal fittings 25a to 25c in the support insulator are provided on each side excluding the opening 18c, the insulating operation member 21 and the opening 1 of the support insulator are provided.
8c can improve the withstand voltage without disturbing the electric field by an appropriate gap length. In particular, insulation operation dedicated 21
However, since the distance between the electrodes is shorter than that of the supporting insulator 18b, electric field concentration is likely to occur. However, since the insulating layer of the supporting insulator 18b having a lower relative dielectric constant than the insulating gas is close, the electric field intensity can be suppressed. .

Further, since the insulating operation member 21 is arranged along the U-shaped opening 18c, a space is reduced as compared with a structure in which a general rotationally symmetrical support insulator and the insulating operation member 21 are individually arranged. Can be smaller.

Each of the embedding fittings 25a, 25b,
Since the portion 25c is divided, the volume of the metal embedded in the insulating layer of the support insulator 18b can be reduced. For this reason, the temperature of the mold can be quickly raised at the time of molding, the adhesion to the insulating resin is improved, defects such as voids and peeling are hardly generated, and good insulating properties can be obtained.

Furthermore, since each of the embedding metal fittings 25 has the same potential, even if each embedding metal fitting (electrode) is small, it becomes an apparently large embedding metal fitting (electrode). Therefore, the lower electric field relaxing electrode 16 fixed to the support insulator 18b
The electric field of the supported object such as the b and the vacuum valve 11 can be reduced. In other words, by making the embedded metal fittings 25 apparently larger with respect to the electrode 16 for alleviating the electric field and the vacuum valve as the object to be supported, the electrodes on the insulating gas side are affected, and the electric field strength can be suppressed. FIG. 4 is a schematic diagram for explaining the relationship between the fixed structure using the supporting insulator and the electric field relaxation. As shown, the upper support insulator 18a
The diameter of the electrode 27 embedded in the insulating layer 26 is φ1
Assuming that the diameter of the electric field relaxing electrode 16a is φ2, the electric field can be mitigated by making the relationship of φ1> φ2. That is, the equipotential lines 28 near the electric field relaxing electrode 16a are expanded by the support insulator 18a, and the electric field is relaxed. Therefore, since the radius of curvature of the electric field relaxing electrode 16a can be reduced, the shape of the electric field relaxing electrode 16a itself can be reduced. (Electric field relaxation by coating having low relative permittivity) Compared with the relative permittivity of the coatings 23a and 23b of the electrodes 16a and 16b, the relative permittivity of the supporting insulators 18a and 18b for supporting and fixing the electrodes 16a and 16b is small. Is higher, the effect of the electric field relaxation by the coatings 23a and 23b can be significantly exhibited. This is because, by forming the supporting insulators 18a and 18b with an insulating material having a high relative permittivity, equipotential lines on the creeping surface are widened. Further, in the coated electric field relaxing electrodes 16a and 16b, the electric potential sharing is determined between the electric field relaxation electrodes 16a and 16b, so that the films 23a and 23
b can reduce the potential sharing of the gas gap G. From these facts, it is possible to reduce the size of the coated electric field relaxing electrode and the supporting insulator for fixing it.

As described above, according to the present embodiment, in a quasi-equivalent electric field having a large electric field utilization factor, the radius of curvature of the electric field relaxing electrodes 16a and 16b is increased by forming the coating 23a made of an insulating material on the electrode surface. Since the withstand voltage characteristics can be improved without reducing the radius of curvature, the radius of curvature can be reduced to reduce the electric field relaxing electrode 16.
a and 16b can be reduced, and the insulation distance between the phases and the ground of the vacuum circuit breaker can be shortened, so that downsizing and downsizing can be achieved.

Further, since the coatings 23a and 23b have a thickness of about 25 μm and are made of Teflon resin or epoxy resin, the electric field can be easily and reliably relaxed by the coatings 23a and 23b.

Further, in an uneven electric field having a small electric field utilization rate, the end of the electric field relaxing electrode is separated from the insulating tube 13 of the vacuum valve 11 by several mm so that the end of the electrode for synergizing with the electrode 24 provided on the insulating tube 13 is formed. By using the effect of relaxing the electric field by the effect, the withstand voltage can be improved.

The supporting insulator 18b for fixing the vacuum valve 11 is U-shaped, and the insulating opening 21 for opening and closing the vacuum valve 11 is provided in the U-shaped opening 18c. By disposing an insulator made of the same insulating material at 18c, the disturbance of the electric field can be reduced and the withstand voltage can be improved. Further, the space between the support insulator 18b and the insulating operation member 21 can be reduced, and the overall shape can be reduced.

Further, by dividing the buried electrodes 25a to 25c into a plurality of parts, the volume of the buried metal can be reduced and the temperature of the mold can be quickly raised at the time of molding. Good insulation characteristics can be realized by making it difficult to generate defects such as peeling and peeling. In addition, since each of the divided embedded electrodes can be apparently made a large electrode, the electric field of a supported object such as the vacuum valve 11 fixed to the supporting insulators 18a and 18b can be reduced.

Further, since the supporting insulator 18a has the electrode 27 having an outer diameter larger than the outer diameter of the electric field relaxing electrode 16a, the equipotential line 28 near the electric field relaxing electrode 16a can be widened to relax the electric field. The radius of curvature of the electric field relaxing electrode 16a can be reduced, and the shape of the electric field relaxing electrode 16a can be reduced.

Further, since the supporting insulators 18a and 18b have a higher relative dielectric constant than the insulating material of the coatings 23a and 23b, the equipotential lines 28 in the region along the supporting insulators 18a and 18b are expanded to increase the electric field. Since the relaxation can be achieved, the radius of curvature of the electric field relaxing electrodes 16a and 16b can be reduced, and the shape of the electric field relaxing electrodes 16a and 16b can be reduced. (Other Embodiments) In another embodiment, in an outlet portion of a support insulator for fixing a main circuit conductor or an instrument transformer, a portion of an electrode facing an insulating gas is coated with an insulating material using a quasi-equal electric field. Alternatively, the fixed side with the supporting insulator or the like may be used alone as an unequal electric field, and the electric field may be alleviated by the synergistic effect of the combination of the fixed side and the supporting insulator, thereby reducing the overall shape. In addition, the present invention can be implemented with various modifications without departing from the scope of the invention.

[0041]

As described above, according to the present invention, there is provided a gas-insulated vacuum circuit breaker capable of improving the withstand voltage without increasing the radius of curvature of the electric field relaxing electrode and thereby achieving downsizing. it can.

[Brief description of the drawings]

FIG. 1 is a side view showing the internal configuration of a gas-insulated vacuum circuit breaker according to one embodiment of the present invention.

FIG. 2 is an enlarged schematic view showing a part of an electric field relaxing electrode in the embodiment.

FIG. 3 is a perspective view showing a configuration of a lower support insulator in the embodiment.

FIG. 4 is a schematic diagram for explaining a relationship between a fixing structure using a supporting insulator and electric field relaxation in the embodiment.

FIG. 5 is a characteristic diagram showing a result of an investigation of a relationship between a breakdown voltage and the presence or absence of a film in the same embodiment while changing a radius of curvature.

FIG. 6 is a side view showing a general gas insulated switchgear and its peripheral configuration.

FIG. 7 is a schematic view showing an electric field relaxation structure of a gas insulated vacuum circuit breaker.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Vacuum valve 12 ... Sealed electrode 13 ... Insulating cylinder 16a, 16b ... Electric field relaxation electrode 15 ... Bolt 17 ... Insulating support plate 18a, 18b ... Support insulator 18c ... Opening 19 ... Flange 20 ... Russell mechanism part 21 ... Insulation Operation 22: Operation mechanism 23a, 23b: Coating 24, 27: Electrodes 25a to 25c: Embedded metal fittings 26: Insulating layer 28: Equipotential line

Claims (7)

[Claims] 1. A gas-insulated vacuum circuit breaker having a vacuum valve filled with an insulating gas and having an insulating container and an electric-field-mitigating electrode having two ends separated by a gas gap G at both ends of the insulating container. An electric field utilization factor U obtained by the following equation based on the radius of curvature R of the outer peripheral surface of the electric field relaxing electrode and the gas gap G is set to a quasi-equal electric field of U = 0.35 or more. A gas insulated vacuum circuit breaker characterized in that a coating made of an insulating material is formed on at least a half of the outer peripheral surface except for a portion facing the insulating container. U = R / {0.9 (R + G)} 2. The gas-insulated vacuum circuit breaker according to claim 1, wherein the coating has a thickness of about 25 μm and is formed of an insulating material made of Teflon resin or epoxy resin. Insulated vacuum circuit breaker. 3. A gas-insulated vacuum circuit breaker having a vacuum valve filled with an insulating gas and having an insulating container and electric-field-mitigating electrodes arranged at both ends of the insulating container and separated by a gas gap G at an end thereof. An electric field utilization factor U obtained by the following equation based on the radius of curvature R of the outer peripheral surface of the electric field relaxing electrode and the gas gap G is defined as an uneven electric field of U = 0.26 or less. Insulated vacuum circuit breaker. U = R / {0.9 (R + G)} 4. A gas-insulated vacuum circuit breaker comprising: a vacuum valve filled with an insulating gas and having an insulating container and electric-field-mitigating electrodes disposed at both ends of the insulating container at an end separated by a gas gap G. An insulating operation member connected to a movable electrode of the vacuum valve and configured to be able to advance and retreat in a direction substantially perpendicular to the axial direction of the vacuum valve; and disposed opposite to each other along the axial direction of the insulating operation rod; A gas-insulated vacuum circuit breaker, comprising a substantially U-shaped recess at a portion facing the insulating operation member, and a supporting insulator for fixing the vacuum valve. 5. The gas-insulated vacuum circuit breaker according to claim 4, wherein the support insulator has a substantially elliptical cross-sectional shape, and is embedded in the first and the second parallel to the axial direction of the vacuum valve. 2 embedded electrodes, and a third embedded electrode having a substantially elliptical cross-sectional shape and embedded so as to face the insulating operating rod via the first and second embedded electrodes. A gas insulated vacuum circuit breaker characterized by the above. 6. The gas-insulated vacuum circuit breaker according to claim 4, wherein an electrode having an outer diameter larger than an outer diameter of the electric field relaxing electrode is embedded to fix the vacuum valve. A gas-insulated vacuum circuit breaker, comprising: a support insulator according to (2). 7. The gas-insulated vacuum circuit breaker according to claim 1, further comprising a supporting insulator for fixing the vacuum valve with a relative permittivity higher than a relative permittivity of an insulating material of the coating. Features a gas-insulated vacuum circuit breaker.