JP4005982B2 - Gas insulated vacuum circuit breaker - Google Patents

Description

  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 electric field relaxation and withstand voltage and reduces insulation.

  In recent years, power receiving and distribution equipment such as gas-insulated switchgear has been improved in insulation withstand voltage by an insulating gas, and the installation space has been reduced.

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 3 </ b> A is accommodated in the chamber 1 a above the box 1. Further, a gas insulated vacuum circuit breaker 4 and a disconnector 3B having the same shape as the upper disconnector 3A are accommodated in the lower chamber 1b of the box 1. Each storage device in the insulating gas is 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, the feed-through current transformer 9 measures the power reception and energization current to the gas-insulated switchgear. Further, the main circuit conductor in the chamber 1a above the box 1 is electrically connected to the adjacent boards arranged in the upper and lower directions in the drawing by an air-gas bushing 10 provided on the ceiling of the box 1. ing.

  In such a gas-insulated switchgear, each storage device exhibits an electric field dependence in which the breakdown voltage of the insulating gas 2 is strong, 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 is for electric field relaxation having a large curvature up to the position where it wraps with the insulating cylinder 13 in order to relax the electric field of the sealing electrode 12 of the vacuum valve 11. Electrode 14 is attached by bolt 15. Such an electric field relaxation method is disclosed in, for example, Japanese Utility Model Publication No. 1-15071, and an electric field relaxation electrode 14 having a diameter larger than the diameter of the vacuum valve 11 is used. In the electric field relaxation 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 inter-pole direction 14A and the inter-phase direction 14B, and the curved surfaces are continuously formed. Thereby, the electric field relaxation electrode 14 is intended to relax the electric field alone.

  However, the gas insulated vacuum circuit breaker as described above has a problem that the electric field relaxation is achieved by increasing the radius of curvature of the electric field relaxation electrode 14 to improve the withstand voltage, while the electric field relaxation electrode 14 is enlarged.

  That is, from the viewpoint of electric field relaxation, even if the radius of curvature of the electric field relaxation electrode 14 is increased and the gas gap is shortened, the electric field relaxation electrode 14 itself is increased in size, so that the arrangement of three phases results. However, there is a problem that becomes larger. That is, there is a limit to downsizing based on electric field relaxation with a large radius of curvature. Moreover, it goes against the recent trend of downsizing.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a gas-insulated vacuum circuit breaker that can improve the withstand voltage without increasing the radius of curvature of the electric field relaxation electrode, and can be reduced in size. And

According to a first aspect of the present invention, there is provided a gas insulating apparatus comprising a vacuum valve that includes an insulating gas, and includes an insulating container and an electric field relaxation electrode having ends disposed at both ends of the insulating container and separated by a gas gap G. In the vacuum circuit breaker, an insulation operation element connected to the movable electrode of the vacuum valve and formed to be movable back and forth along a direction substantially perpendicular to the axial direction of the vacuum valve, and along the axial direction of the insulation operation rod. A support insulator that is disposed opposite to the insulating operation rod, has a substantially U-shaped concave portion coaxial with the insulating operation rod, and a support insulator for fixing the vacuum valve. the said insulation operation rod insulator Ri name of the same insulating material, as the supporting insulators, has a substantially elliptical cross-sectional shape, the first and second of embedded parallel to the axial direction of the vacuum valve Embedded electrode and a substantially elliptical cross section And a third embedded electrode embedded so as to face the insulating operation rod via the first and second embedded electrodes, and the first to third embedded electrodes are mutually connected The apparent electrode composed of the first to third embedded electrodes having the same potential is a gas-insulated vacuum circuit breaker larger than the individual embedded electrodes .

(Function)
Therefore, in the invention corresponding to claim 1, the support insulator for fixing the vacuum valve is formed in a U-shape, and the U-shaped opening is provided with an insulating operation for opening and closing the vacuum valve. An insulator made of the same insulating material is positioned in the part to reduce the electric field disturbance and improve the withstand voltage. Furthermore, the space for the support insulator and the insulation operation can be reduced, and the overall shape can be reduced.

Furthermore, the invention corresponding to claim 1 divides the embedded electrode into a plurality of parts, so that the volume of the embedded metal can be reduced, and the temperature of the mold can be quickly raised during molding, and the adhesiveness with the insulating resin is improved. Thus, it is difficult to generate defects such as voids and peeling, and good insulation characteristics can be realized. In addition, since each of the divided embedded electrodes can be formed into an apparently large electrode, the electric field of a supported object such as a vacuum valve fixed to a support insulator can be reduced.

  As described above, according to the present invention, it is possible to provide a gas-insulated vacuum circuit breaker capable of improving the withstand voltage without increasing the radius of curvature of the electric field relaxation electrode and thereby reducing the size.

  Hereinafter, an embodiment of the present invention will be described 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. Only about.

  That is, this embodiment is intended to realize electric field relaxation without increasing the radius of curvature of the electric field relaxation electrode, and specifically has the structure described below.

  In FIG. 1, electric field relaxation electrodes 16 a and 16 b that serve both as electric field relaxation and energization are provided above and below the vacuum valve 11. The electric field relaxation electrodes 16a and 16b are fixed to each other via an insulating support plate 17 parallel to the axial direction of the vacuum valve, and to the flange 19 via respective support insulators 18a and 18b perpendicular to the axial direction of the vacuum valve. The support is fixed.

  Further, in the lower electric field relaxation electrode 16b, there is a Russell mechanism portion 20 for opening and closing a movable electrode (not shown) in the vacuum valve 11, and an insulation operation portion 21 connected to the Russell mechanism portion 20 is provided at the lower portion. Are arranged in parallel with the insulator 18b. The insulation operation deed 21 is connected to the operation mechanism unit 22 on the air side.

  On the other hand, in the upper electric field relaxation electrode 16a, a coating 23a made of an insulating material such as Teflon resin or epoxy resin is formed on the upper surface excluding the surface facing the vacuum valve 11. The insulating thickness of the film is several tens of μm, and is approximately 25 μm here. Similarly, a coating 23b is formed on the lower side of the lower electric field relaxation electrode 16b except for the surface facing the vacuum bulb 11. That is, the electric field relaxation electrode on which the coatings 23a and 23b are formed is opposed to the insulating cylinder through the gas gap G as shown in an enlarged view in FIG. A large quasi-equal electric field can be realized. The dielectric constant of the insulating material of the film is smaller than the dielectric constant of the supporting insulator.

  Specifically, the electric field relaxation electrode 16a is fixed by a bolt 15, and the lower surface is a base without a film or the like formed thereon. The end portion of the electric field relaxation electrode 16a extends to the vicinity of the electrode portion 24 that couples the sealing electrode 12 of the vacuum valve 11 and the insulating cylinder 13, and the gap length G is maintained from the end of the insulating cylinder 13 to a few mm. Is located. Therefore, in the lower part of the electric field relaxation electrode 16a (or on the side facing the insulating cylinder), an unequal electric field having an acute angle at the end is obtained.

  Further, as shown in FIG. 3, the support insulator 18 b is provided with a U-shaped opening 18 c coaxially facing the insulation operation element 21. That is, the insulating operation elements 21 are arranged in parallel along the opening 18c. The gap between the insulating operation 21 and the opening 18c is set to a value of several tens of millimeters, which is an appropriate value that does not cause partial discharge. Further, in the support insulator, each of the embedded metal fittings 25a, 25b, 25c is provided on each side excluding the opening 18c.

  As shown in FIG. 4, the upper support insulator 18a is embedded with an electrode 27 connected to the end of the electric field relaxation electrode 16a, and the electrode 27 supports the electric field relaxation electrode 16a in a fixed manner. Yes. Here, the diameter φ1 of the electrode 27 in the support insulator 18a and the diameter φ2 of the electric field relaxation electrode 16a are preferably in a relationship of φ1> φ2 from the viewpoint of electric field relaxation due to the expansion of the equipotential line 28.

  Next, the operation of the gas insulated vacuum circuit breaker configured as described above will be described. In addition, since each structure implement | achieves an electric field relaxation each independently, an effect | action is demonstrated for every structure separately.

(Electric field relaxation by coating)
FIG. 5 is a voltage characteristic diagram showing the result of investigating the relationship between the breakdown (impulse flashover) voltage and the presence / absence of a film by changing the radius of curvature. The characteristic of the black mark compares the breakdown voltage in the electric field relaxation electrodes 16a and 14 having a radius of curvature R = 40 mm and disposed in the gas gap 10 mm with or without the coating 23a. The white mark characteristics are such that the electric field relaxation electrodes 16a and 14 in the black mark characteristics have a curvature radius R = 3 mm. Here, when the former R = 40 mm, the electric field utilization factor U = 0.88 is a quasi-equal electric field, and when the latter R = 3 mm, the electric field utilization factor U = 0.26 is an unequal electric field. The electric field utilization factor U can be approximated by the following equation.

Electric field utilization factor U = R / {0.9 (R + G)}
Where R: radius of curvature of electrode, G: gas gap length.

  From the figure, in the quasi-equal electric field, the breakdown voltage is increased by about 25% compared to the bare electrode when the electrode has the coating 23a. On the other hand, in the unequal electric field, the breakdown voltage of the electrode having the coating 23a hardly increases. In the electric field relaxation electrode 16a shown in FIG. 2, the breakdown voltage could be increased by about 10% when the radius of curvature R = 30 mm, the gas gap G = 65 mm, and the electric field utilization rate U = 0.35. That is, since the effect of the film 23a appears in proportion to the electric field utilization factor U (or as the field becomes equal), it can be said that the breakdown voltage can be increased using the film 23a. Specifically, it is estimated that the coating 23a has an effect of smoothing unevenness on the surface of the electrode to suppress the electric field strength and suppress 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 shortened. Therefore, 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. Reduction can be achieved. If it is difficult to form the coating film 23 on about half of the electric field relaxation electrode 16, the coating film 23 may be provided on the entire surface of the electric field relaxation electrode 16.

  Here, the end portion of the electric field relaxation electrode 16a forms an unequal electric field by itself, but the electric field relaxation as a whole shape by a synergistic effect with the electrode 24 to be coupled to the insulating cylinder 13 in combination with the vacuum valve 11. Can be achieved. This electric field relaxation is greatly influenced by the gas gap length G between the insulating cylinder 13 and the end portion of the electric field relaxation electrode 16a. According to experiments, when the gas gap G is about 2 mm, there was no destruction from the gas gap portion. When the gas gap G cannot be formed and is wrapped with the insulating cylinder 13, the breakdown voltage is most lowered. Although the configuration of the upper electric field relaxation electrode 16a has been described as an example, the lower electric field relaxation electrode 16b may have the same configuration.

(Electric field relaxation by embedded metal fittings)
Since each of the embedded metal fittings 25a to 25c in the support insulator is provided on each side except the opening 18c, the insulation operation 21 and the opening 18c of the support insulator have a withstand voltage without disturbing the electric field due to an appropriate gap length. Improvements can be made. In particular, in insulation operation cowpea 21 is prone to the electrode distance is shorter electric field concentration than the support insulators 18b, since the insulating layer supporting region insulators 18b are close, it is possible to suppress the electric field strength.

  Further, since the insulating operation element 21 is disposed along the U-shaped opening 18c, the space can be reduced as compared with the structure in which the general rotationally symmetric support insulator and the insulating operation element 21 are individually disposed.

  In addition, since each of the embedded metal fittings 25a, 25b, and 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 adhesiveness with the insulating resin is improved, and defects such as voids and peeling are difficult to occur, and good insulating properties can be obtained.

  Furthermore, since each embedded metal fitting 25 has the same potential, even a small embedded metal fitting (electrode) is apparently a large embedded metal fitting (electrode). Therefore, it is possible to reduce the electric field of the object to be supported such as the lower electrode 16b for electric field relaxation and the vacuum valve 11 fixed to the support insulator 18b. That is, by apparently enlarging the embedded metal fitting 25 with respect to the electric field relaxation electrode 16 or vacuum valve as a supported object, the electrode on the insulating gas side can be affected, and the electric field strength can be suppressed.

(Electric field relaxation by large-diameter embedded electrode)
FIG. 4 is a schematic diagram for explaining the relationship between the fixing structure by the supporting insulator and the electric field relaxation. As shown in the figure, when the diameter of the electrode 27 embedded in the insulating layer 26 is φ1 and the diameter of the electric field relaxation electrode 16a is φ2 in the upper support insulator 18a, the relationship between the two is φ1> φ2. Thus, electric field relaxation can be achieved. That is, the equipotential line 28 in the vicinity of the electric field relaxation electrode 16a is widened by the support insulator 18a, and the electric field is relaxed. Therefore, since the radius of curvature of the electric field relaxation electrode 16a can be reduced, the shape of the electric field relaxation electrode 16a itself can be reduced.

(Electric field relaxation by low dielectric constant film)
If the relative dielectric constants of the support insulators 18a and 18b for supporting and fixing the electric field relaxation electrodes 16a and 16b are made higher than the relative dielectric constants of the coating films 23a and 23b of the electric field relaxation electrodes 16a and 16b, the coating films 23a and 23b. The effect of relaxing the electric field can be greatly exhibited. This is because the equipotential lines on the creeping surface are widened by forming the support insulators 18a and 18b with an insulating material having a high relative dielectric constant. Further, in the coated electric field relaxation electrodes 16a and 16b, since the potential sharing with the gas gap G is determined, the coating 23a and 23b having a lower relative dielectric constant can reduce the potential sharing of the gas gap G. As a result, it is possible to reduce the size of the coated electric field relaxation electrode and the support insulator for fixing the electrode.

  As described above, according to the present embodiment, in a quasi-equal electric field having a large electric field utilization factor, the formation of the coating 23a made of an insulating material on the electrode surface does not increase the curvature radius of the electric field relaxation electrodes 16a and 16b. Since the withstand voltage characteristics can be improved, the curvature radius can be reduced to reduce the electric field relaxation electrodes 16a and 16b, and the insulation distance between the phases of the vacuum circuit breaker and the ground can be shortened, thereby achieving miniaturization and reduction in size. be able to.

  Further, since the coatings 23a and 23b have a thickness of approximately 25 μm and are formed of Teflon resin or epoxy resin, electric field relaxation by the coatings 23a and 23b can be easily and reliably achieved.

  Further, in an unequal electric field with a small electric field utilization factor, the electric field due to a synergistic effect with the electrode 24 provided on the insulating cylinder 13 is obtained by separating the end of the electric field relaxation electrode from the insulating cylinder 13 of the vacuum valve 11 by several mm. It is possible to improve the withstand voltage by acting a relaxation action.

  Further, the support insulator 18b for fixing the vacuum valve 11 is U-shaped, and the U-shaped opening 18c is provided with an insulating operation 21 for opening and closing the vacuum valve 11, so that the U-shaped opening 18c is identical. It is possible to reduce the electric field disturbance by positioning an insulator made of this insulating material, and to improve the withstand voltage. Furthermore, the space for the support insulator 18b and the insulating operation 21 can be reduced, and the overall shape can be reduced.

  Further, by dividing the embedded electrodes 25a to 25c into a plurality of parts, the volume of the embedded metal can be reduced, and the temperature of the mold can be quickly raised at the time of molding. This makes it difficult to generate defects and realizes good insulation characteristics. In addition, each of the divided embedded electrodes can be formed into a large electrode, so that the electric field of the supported object such as the vacuum bulb 11 fixed to the support insulators 18a and 18b can be reduced.

  In addition, since the support insulator 18a has the electrode 27 having an outer diameter larger than the outer diameter of the electric field relaxation electrode 16a, the electric field can be relaxed by widening the equipotential line 28 in the vicinity of the electric field relaxation electrode 16a. The radius of curvature of the electrode 16a can be reduced, and the shape of the electric field relaxation electrode 16a can be reduced.

  Further, since the support insulators 18a and 18b have a relative dielectric constant higher than that of the insulating material of the coatings 23a and 23b, the equipotential lines 28 in the regions along the support insulators 18a and 18b can be widened to relax the electric field. The radius of curvature of the electric field relaxation electrodes 16a and 16b can be reduced, and the shape of the electric field relaxation electrodes 16a and 16b can be reduced.

(Other embodiments)
As another embodiment, in the lead-out part of the support insulator for fixing the main circuit conductor or the transformer for the instrument, the insulating material is coated with the quasi-equal electric field at the portion of the electrode facing the insulating gas, the support insulator, etc. The non-uniform electric field alone may be used as the non-uniform electric field, and electric field relaxation may be realized by a synergistic effect of the combination of the fixed side and the support insulator, thereby reducing the overall shape.

  In addition, the present invention can be implemented with various modifications without departing from the gist thereof.

The side view which shows the internal structure of the gas insulated vacuum circuit breaker which concerns on one Embodiment of this invention. The schematic diagram which expands and shows a part of electrode for electric field relaxation in the embodiment The perspective view which shows the structure of the lower support insulator in the embodiment Schematic diagram for explaining the relationship between the fixed structure by the support insulator and the electric field relaxation in the embodiment The characteristic figure which shows the result of having investigated the relationship between the breakdown voltage and the presence or absence of a film in the same embodiment by changing the radius of curvature Side view showing a general gas-insulated switchgear and its peripheral configuration Schematic diagram showing the electric field relaxation structure of a gas insulated vacuum circuit breaker

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Vacuum valve, 12 ... Sealing electrode, 13 ... Insulating cylinder, 16a, 16b ... Electrode for electric field relaxation, 15 ... Bolt, 17 ... Insulating support plate, 18a, 18b ... Support insulator, 18c ... Opening, 19 ... Flange , 20 ... Russell mechanism part, 21 ... insulation operation dedicated, 22 ... operation mechanism part, 23a, 23b ... coating, 24, 27 ... electrode, 25a to 25c ... embedded metal fitting, 26 ... insulating layer, 28 ... equipotential line.

Claims (1)

In a gas-insulated vacuum circuit breaker comprising a vacuum valve which encloses an insulating gas and has an insulating container and an electric field relaxation electrode disposed at both ends of the insulating container by a gas gap G and having an end portion disposed.
An insulating operation connected to the movable electrode of the vacuum valve and formed to be movable back and forth along a direction substantially perpendicular to the axial direction of the vacuum valve;
It is disposed opposite to the insulation operation rod along the axial direction of the insulation operation rod, and has a substantially U-shaped concave portion coaxial with the insulation operation rod at a portion facing the insulation operation deed, and the vacuum valve It has a support insulator to fix,
The support Ri name of the same insulating material and the insulating operating rod and insulators,
The support insulator is
First and second embedded electrodes having a substantially elliptical cross-sectional shape and embedded in parallel to the axial direction of the vacuum valve;
A third embedded electrode having a substantially elliptical cross-sectional shape and embedded so as to face the insulating operation rod via the first and second embedded electrodes;
The gas-insulated vacuum circuit breaker characterized in that the first to third embedded electrodes are at the same potential, and an apparent electrode made of the first to third embedded electrodes is larger than each embedded electrode . .

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