Gas-insulated switchgear

Abstract

Provided is a structure suitable for a gas-insulated switchgear when using an alternative gas for SF6 gas. The gas-insulated switchgear has a pressure vessel, an electric contact provided inside the pressure vessel, and an insulating gas filled in the pressure vessel, wherein the cross-sectional shape of the pressure vessel has a curved surface.

Description

Gas-insulated switchgear

[0001] The present invention relates to a gas-insulated switchgear.

[0002] Gas-insulated switchgear is a type of switchgear that uses insulating gas as an insulating medium to enable high-voltage operation of the switchgear. Conventionally, SF6, known as a high-performance gas, has been widely used as the insulating gas. However, as the destruction of the ozone layer by fluorine-based gases has become a social issue, there is a growing demand for high-voltage switchgear that does not use chlorofluorocarbons.

[0003] Patent Document 1 discusses downsizing of equipment when an alternative gas to SF6 gas is used.

[0004] Japanese Patent Application Laid-Open No. 2006-352972

[0005] The switching device described in Patent Document 1 is designed to be compact, but the design is limited to the details and does not go into a fundamental investigation of the overall structure.

[0006] In order to solve the above problems, the present invention aims to provide a desirable gas-insulated switchgear structure when using an alternative gas to SF6 gas.

[0007] An example of the safety work device of the present invention for solving the above problems is as follows.

[0008] A gas-insulated switchgear having a pressure vessel, an electrical contact provided within the pressure vessel, and an insulating gas filled in the pressure vessel, wherein the cross-sectional shape of the pressure vessel has a curved surface.

[0009] According to the present invention, it is possible to provide a structure suitable for a gas-insulated switchgear when an alternative gas to SF6 gas is used.

[0010] Further configurations and effects of the present invention will become apparent from the entire specification below.

[0011] FIG. 1 is a schematic cross-sectional structural view of an example of a gas-insulated switchgear of the present invention. FIG. 2 is a top view of an example of a gas-insulated switchgear of the present invention. FIG. 3 is a side view of an example of a gas-insulated switchgear of the present invention. FIG. 4 is a rear view of an example of a gas-insulated switchgear of the present invention. FIG. 5 is a front view of an example of a gas-insulated switchgear of the present invention. FIG. 6 is an explanatory view of a bottom plate of an example of a gas-insulated switchgear of the present invention. FIG. 7 is an explanatory view of a bottom plate of an example of a gas-insulated switchgear of the present invention.

[0012] FIG. 1 is a schematic cross-sectional structural view of an example of a gas-insulated switchgear according to the present invention.

[0013] Reference numeral 10 denotes a bus room and 12 denotes an equipment room. Together, these make up a tank 11. Pressurized dry air is sealed in both the bus room 10 and the equipment room 12. This is an example of an alternative gas to SF6 gas. The alternative gas used is not limited to pressurized dry air, but it is assumed that it does not exhibit ozone layer depletion properties.

[0014] Furthermore, the insulating performance per unit volume of dry air is inferior to that of SF6. To compensate for this, in this embodiment, dry air is pressurized and sealed at a gas pressure of 0.31 MPa. This gas pressure is higher than the gas pressure when SF6 is normally used. This effectively increases the amount of gas per unit volume, thereby compensating for the difference in insulating characteristics due to the change in insulating gas.

[0015] The problem here is that the gas pressure must be increased, or more specifically, it must be increased. This increases the gas pressure on the tank, and a thicker, heavier tank is required to withstand this pressure. Patent Document 1 also partially considers downsizing the equipment when using alternative gases, but does not fully consider the tank itself.

[0016] There are two easy solutions. One is to make the tanks larger, but this goes against another social demand for smaller tanks. The other is to make the tanks thicker. However, this would increase the number of materials used and the energy required for transportation and manufacturing, which would worsen the environmental impact in other ways.

[0017] Therefore, the greatest feature of the present invention is that the tank structure is changed from the conventional rectangular shape to a structure with curved surfaces.

[0018] The concept of the present invention will be explained first with reference to Figure 2. While the details will be described later, a major feature is that the tank 11 has a curved structure. This allows for less gas pressure concentration compared to a rectangular structure, i.e., a structure with extensive corners, and therefore allows for improved pressure resistance per unit area compared to a rectangular structure. As a result, the tank can be made more compact or its wall thickness can be reduced. Although a curved surface is mentioned here, a circular shape would be ideal. Therefore, the following explanation will be given using an example of a circular shape.

[0019] Returning to Figure 1, the internal structure of the gas-insulated switchgear will be described. In this embodiment, the built-in equipment itself does not require a specially designed design. This is also one of the advantages of the present invention.

[0020] The busbar chamber has a side input / output section 19. A first input / output terminal 41 is introduced into the tank 11 from the side input / output section 19. The opening of the side input / output section 19 is firmly fixed and sealed with an insulating resin member, for example, epoxy resin.

[0021] The current introduced from the first input / output terminal 41 is introduced into the disconnector 20 via the conductor 40. The disconnector 20 drives one of the pair of first electrodes 21 using a drive unit, and the current is turned on and off by the contact and separation between the electrodes.

[0022] The current introduced by the disconnector 20 is introduced into the vacuum circuit breaker 22 through a conductor 40. The current is turned on and off by contacting and separating a pair of electrodes within a space maintained in a vacuum state.

[0023] The conductor 40 runs from the busbar room 10 to the equipment room 12, with a spacer 14 between them to provide airtight separation between the busbar room 10 and the equipment room 12. The spacer 14 is insulated to prevent a problem such as a short circuit from spreading to the other room and expanding the scale of the problem if such a problem occurs in either the busbar room 10 or the equipment room 12.

[0024] The current passes through the vacuum circuit breaker 22 and enters the disconnector 23 via the conductor 40. The disconnector 23 drives one of a pair of second electrodes 24 using a drive unit, and the current is turned on and off depending on the contact and separation between the electrodes. The current turned on by the disconnector 23 flows through the conductor 40 to the second input / output terminal 42. In this way, the current in the gas-insulated switchgear is turned on and off.

[0025] The first input / output terminal 41 and the second input / output terminal 42 are input terminals and output terminals, respectively. Their names and roles vary depending on how they are used. Alternatively, one may be referred to as the power source side and the other as the power consumption device side.

[0026] 1 also shows a grounding switch 25. This is used when driving either of the pair of third electrodes 26 to set the entire device at ground potential.

[0027] Also disclosed is a lightning arrester 27. While it appears to be always connected in the diagram, it is made of a unique material, a special insulator that only exhibits conductivity under high voltage. One example is zinc oxide. By using this material, a structure is realized in which, although it is technically connected, it is electrically insulated under normal conditions, but becomes conductive under extremely high voltages such as lightning strikes. This device prevents damage to equipment by dissipating unexpected high voltages, such as lightning strikes, to the ground potential connected to the lightning arrester.

[0028] The structure of the tank 11 will be further explained with reference to Figure 1. Reference numeral 15 denotes a first circular hatch, and 16 denotes a second circular hatch. The first circular hatch 15 is larger than the second circular hatch 16. This is because the first circular hatch 15 is required to provide electrical continuity for the second input / output terminals 42. In particular, when the second input / output terminals 42 are three-phase, three terminals must be provided. Therefore, the first circular hatch 15 is made larger than the second circular hatch 16 to ensure an insulating distance between the terminals.

[0029] The second circular hatch 16 is mainly intended for inspection and for installing equipment during manufacturing. Therefore, if other methods can be used instead, the second circular hatch 16 is not essential. However, considering the actual work area and maintenance, it is desirable to provide it.

[0030] The tank 11 has a first rectangular hatch 17 and a second rectangular hatch 18 on the surface opposite to the first circular hatch 15 .

[0031] The second rectangular hatch 18 is a hatch for installing the disconnector 20 in the tank 11. The first rectangular hatch 17 is a hatch for installing the disconnector 23 and the drive unit of the vacuum circuit breaker 22 in the tank 11.

[0032] As is clear, when comparing the first rectangular hatch 17 with the second rectangular hatch 18, the first rectangular hatch 17 is larger. Therefore, from the viewpoint of pressure response to an increase in gas pressure, consideration of the first rectangular hatch 17 is more important.

[0033] Therefore, in the present invention, we have gone beyond giving the tank 11 a curved surface and have investigated the desirable configuration for the shape and size of the hatch to accommodate increased gas pressure.

[0034] As a result, the inventors of the present invention found that the greater the maximum width of the opening in the lateral direction, the greater the pressure applied by the hatch.

[0035] Therefore, in the present invention, a further configuration is employed in a gas-insulated switchgear having multiple hatches, in which the wider the hatch is in the lateral direction, the thicker the hatch wall is. As an example, the first circular hatch 15 is 830 mm in diameter, i.e., the width is 830 mm, but the wall thickness is 32 mm. Similarly, the first rectangular hatch 17 is 590 mm in width, but the wall thickness is 9 mm. This ensures safety even when hatches are provided in a gas-insulated switchgear that is pressurized using dry air, and also reduces wall thickness where possible, thereby achieving improved environmental performance through weight reduction and reduced component usage.

[0036] Furthermore, the evaluation results showed that the difference in maximum vertical width had a smaller effect on the tank's pressure resistance than the difference in maximum horizontal width. Although the exact reason is not clear, it is currently assumed that when using a circular tank, the horizontal cross section changes continuously, making it susceptible to the effects of differences in gas pressure and shape, whereas the vertical cross section remains the same and does not change, making it less susceptible to the effects of differences in gas pressure and shape.

[0037] The structure will be described further with reference to the top view of Figure 2. Note that the same reference numerals as in Figure 1 denote the same components, and therefore will not be described again.

[0038] Reference numeral 45 denotes a bottom plate, and in the top view, it is seen that the corners of the bottom plate protrude from the tank 11. In FIG. 2, the first input / output terminals 41 are a set of three wires corresponding to three phases. They are provided on both the top and bottom in the drawing. However, the present invention also includes the case where they are provided on only one side.

[0039] Also, in the figure, 18 has 17 hidden underneath it. Similarly, 20 in the figure has 22 and 23 hidden underneath it.

[0040] The first circular hatch 15 has an opening / closing door 55 shown on its front side. Although the drawings in this specification include drawings in which the opening / closing door is not separately shown for various hatches, in reality, the hatch has an opening / closing door.

[0041] Fig. 3 is a side view of an example of a gas-insulated switchgear according to the present invention. Since the same reference numerals as in Fig. 1 denote the same components, a repeated explanation will be omitted. Compared to the cross-sectional view of Fig. 1, the tank 11 is circular, and therefore each hatch is formed around the side of the tank 11.

[0042] Figure 4 is a rear view of an example of a gas-insulated switchgear according to the present invention. It corresponds to a view of the exterior of Figure 1 as seen from the right side. Note that the same reference numerals as in Figure 1 denote the same components, and therefore will not be described again. It can be seen that the first circular hatch 15 is larger than the second circular hatch 16.

[0043] Fig. 5 is a front view of an example of a gas-insulated switchgear according to the present invention, which corresponds to the external configuration of Fig. 1 as seen from the left side. Note that the same reference numerals as in Fig. 1 denote the same components, and therefore will not be described again.

[0044] 6 is an explanatory diagram of the bottom plate of an example of a gas-insulated switchgear according to the present invention. Because the tank 11 is circular, a structural feature is that large spaces are created at the corners of the bottom plate 45. Therefore, these large spaces are utilized to provide mounting holes 59. This not only simplifies installation, but also eliminates the need to secure additional space for mounting holes, enabling further miniaturization.

[0045] Figure 7 is a modified example of Figure 6. As can be seen from Figure 6, there is still space in the mounting hole 59 in the direction toward the tank 11. Therefore, in Figure 7, the mounting hole 59 is made an elongated hole in the direction toward the tank 11. This makes it easier to align the mounting hole during assembly and installation, improving work efficiency and reducing time.

[0046] The above-mentioned technical concepts can be used alone or in combination, and these cases are also included within the scope of the present invention.

[0047] Furthermore, as long as the technical concept detailed above is applied, modifications and slight differences in structure are also included within the scope of the present invention.

[0048] An example of the invention disclosed in this specification is as follows.

[0049] <No. 1> A gas-insulated switchgear having a pressure vessel, an electrical contact provided inside the pressure vessel, and an insulating gas filled in the pressure vessel, wherein the cross-sectional shape of the pressure vessel has a curved surface.

[0050] <Item 2> The gas-insulated switchgear according to item <Item 1>, wherein the curved surface is circular.

[0051] <Item 3> The gas-insulated switchgear according to item <Item 2>, wherein the insulating gas is pressurized dry air.

[0052] <Item 4> The gas-insulated switchgear according to item <Item 3>, wherein the pressure vessel has an opening / closing hatch, and the opening / closing hatch has a circular hatch.

[0053] <Item 5> The gas-insulated switchgear according to item <Item 4>, wherein the gas-insulated switchgear has a rectangular hatch different from the circular hatch.

[0054] <No. 6> The gas-insulated switchgear according to <No. 5>, wherein the rectangular hatch has a narrower width in the lateral direction and a thinner wall thickness than the circular hatch.

[0055] <No. 7> The gas-insulated switchgear according to <No. 6>, wherein the rectangular hatch or the circular hatch has a thickness that increases as the width in the lateral direction increases.

[0056] <No. 8> In the gas-insulated switchgear described in <No. 5>, the rectangular hatch is for attaching a driving member, and the size of the parts attached to the rectangular hatch is larger than the size of the parts attached to the circular hatch.

[0057] <No. 9> The gas-insulated switchgear according to <No. 3>, wherein the pressure vessel has a rectangular base on the bottom surface, and mounting holes are provided at corners of the base.

[0058] <Item 10> The gas-insulated switchgear according to item <Item 9>, wherein the mounting hole is an elongated hole extending in a direction toward the pressure vessel.

[0059] 10: Busbar room 11: Tank 12: Equipment room 14: Spacer 15: First circular hatch 16: Second circular hatch 17: First rectangular hatch 18: Second rectangular hatch 19: Side input / output section 20: Disconnector 21: Pair of first electrodes 22: Vacuum circuit breaker 23: Disconnector 24: Pair of second electrodes 25: Earthing switch 26: Pair of third electrodes 27: Lightning arrester 40: Conductor 41: First input / output terminal 42: Second input / output terminal 45: Bottom plate 55: Opening door 56: Opening door 59: Mounting hole

Claims

1. A gas-insulated switchgear having a pressure vessel, electrical contacts provided within the pressure vessel, and insulating gas filled in the pressure vessel, wherein the cross-sectional shape of the pressure vessel has a curved surface.

2. A gas-insulated switchgear according to claim 1, wherein the curved surface is circular.

3. A gas-insulated switchgear according to claim 2, wherein the insulating gas is pressurized dry air.

4. A gas-insulated switchgear according to claim 3, wherein the pressure vessel has an opening / closing hatch, and the opening / closing hatch is a circular hatch.

5. A gas-insulated switchgear according to claim 4, wherein the gas-insulated switchgear has a rectangular hatch different from the circular hatch.

6. A gas-insulated switchgear according to claim 5, wherein the rectangular hatch has a narrower width in the horizontal direction and a thinner wall thickness than the circular hatch.

7. A gas-insulated switchgear according to claim 6, wherein the rectangular hatch or the circular hatch has a greater wall thickness as its lateral width increases.

8. A gas-insulated switchgear according to claim 5, wherein the rectangular hatch is for mounting a driving member, and the size of the parts mounted on the rectangular hatch is larger than the size of the parts mounted on the circular hatch.

9. A gas-insulated switchgear according to claim 3, wherein the pressure vessel has a rectangular base on the underside, and mounting holes are provided at the corners of the base.

10. A gas-insulated switchgear according to claim 9, wherein the mounting hole is an elongated hole extending in a direction toward the pressure vessel.

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