JP4119441B2 - Gas insulated switchgear - Google Patents

Description

  The present invention relates to a gas-insulated switchgear that is applied to an extra-high voltage substation facility for private demand, a power system substation, a switching station, a distribution substation, and the like.

  A conventional gas insulated switchgear supports a high-voltage conductor that forms a main circuit in a grounded sealed container filled with compressed SF6 gas while being electrically insulated from the grounded sealed container, and other circuit breakers. The equipment was configured. However, in recent years, the movement to regulate the use of SF6 gas, whose global warming potential is about 24,000 times higher than that of carbon dioxide, has become stronger due to global environmental problems, and it is essential to reduce the amount of SF6 gas used in equipment as much as possible. It has become. For this reason, a gas insulated switchgear that uses a vacuum circuit breaker instead of the SF6 gas circuit breaker as the circuit breaker and greatly reduces the amount of SF6 gas used is known (for example, see Patent Document 1). Also, as this insulating gas, dry air, nitrogen, carbon dioxide gas, or a mixed gas thereof is known in which c-C4F8, CF3SF5, C3F8, CF3OSF3 having a warming coefficient smaller than that of SF6 gas is mixed ( For example, see Patent Document 2). Since such an insulating gas has a dielectric strength as high as that of SF6 gas, the same product structure as that in the case where SF6 gas is sealed in a grounded sealed container can be adopted to reduce the global warming potential. Furthermore, when using a vacuum circuit breaker, to reduce the pressure difference between the inside and outside of the bellows that allows the movable electrode to open and close while maintaining the degree of vacuum in the vacuum vessel, to prevent the occurrence of fatigue cracks A double bellows is provided, and an intermediate pressure chamber is formed between the two bellows (see, for example, Patent Document 1 and Patent Document 3).

JP-A-60-205926 JP 2001-251714 A JP 63-314732 A

  However, the conventional gas-insulated switchgear uses a vacuum circuit breaker as a circuit breaker, and uses dry air, nitrogen, carbon dioxide gas, or a mixed gas thereof as an insulating gas sealed in a grounded airtight container. Even if a mixture of c-C4F8, CF3SF5, C3F8, and CF3OSF3 with a low activation coefficient is used, the global warming potential is lower than that of SF6 gas, but higher than that of carbon dioxide. In particular, chlorofluorocarbon is a chemically stable substance. Therefore, gas emissions during installation inspection work and leaks during long-term operation accumulate in the atmosphere, which will cause problems in the global environment in the future. Also, when collecting insulating gas from the grounded closed container for internal inspection, etc., if the gas pressure in the grounded sealed container to be recovered is increased, the saturated vapor pressure of c-C4F8, CF3SF5, C3F8, and CF3OSF3 is low and partly Liquefaction occurs, and separation and recovery are required to manage the mixing ratio, and the recovery device becomes large. Conversely, if the recovery tank gas pressure is lowered, the recovery tank becomes larger.

  On the other hand, if dry air, nitrogen, or carbon dioxide gas is used without mixing the above-mentioned chlorofluorocarbon gas, the dielectric strength is less than half that of SF6 gas, so if the pressure is the same, the size of the equipment should be more than twice the insulation distance and volume. It becomes about 8 times or more and becomes very expensive. Moreover, since the current interruption performance of these insulating gases is 30% or less of SF6 gas, the current interruption capability by the insulating gas is greatly reduced. However, when a vacuum circuit breaker is used as a circuit breaker, The load due to the pressure difference between the inside and outside of the bellows used to allow the movable electrode to operate while maintaining the vacuum of the tube is large, the bellows fatigues and cracks due to multiple operations, and the vacuum cannot be maintained, and the vacuum is shut off When the pressure difference is taken into consideration, the insulation performance cannot be improved by increasing the gas pressure.

  An object of the present invention is to provide a gas insulated switchgear that is downsized while suppressing the use of Freon gas such as SF6, c-C4F8, CF3SF5, C3F8, and CF3OSF3.

  In order to achieve the above object, the present invention provides a circuit breaker unit and a disconnector unit by insulatingly supporting a high voltage conductor constituting a main circuit in a grounded sealed container filled with an insulating gas. The unit is a gas-insulated switchgear constituted by a vacuum circuit breaker having a first bellows that maintains the degree of vacuum in the vacuum vessel and allows the movable electrode to be opened and closed. Dividing into compartments, disposing the vacuum circuit breaker in one of the gas compartments to constitute the breaker unit, disposing the disconnector in the other gas compartment to constitute the disconnector unit, An insulating cylinder having one end connected to the vacuum vessel in an airtight manner and the other end connected in an airtight manner to the grounded sealed vessel is provided, the inside of the insulating tube and the inside of the vacuum vessel are communicated, and the other end side of the insulating tube Above true Container and by dividing between the insulating cylinder and the atmosphere, characterized in that a said first bellows.

  According to such a gas-insulated switchgear, the insulating gas in the grounded sealed container in which the vacuum circuit breaker is disposed and the grounded sealed container in which the disconnector is disposed, and the gas pressure thereof are changed between the internal and external gas pressures of the first bellows. In the case of the previous embodiment, the pressure difference applied to the first bellows is the pressure difference between the degree of vacuum in the vacuum container and the atmosphere. Similarly to the above, it is possible to provide a gas insulated switchgear having a small size and more stable performance. Moreover, since only one bellows is used, the configuration is simplified.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a cross-sectional view showing a gas insulated switchgear according to an embodiment of the present invention.
In the grounded sealed containers 11, 41, and 48 filled with the insulating gas, the high voltage conductors constituting the main circuit are electrically connected from the grounded sealed containers 11, 41, and 48 by appropriate insulating supports 9a to 9c and 18. It is configured in an insulated state. The entire grounded airtight container 11, 41, 48 is divided into a plurality of gas sections by insulating spacers 1, 2, a bus bar unit 4 in which a disconnector and a main bus bar are disposed, a circuit breaker unit 10 in which a vacuum circuit breaker 20 is disposed, The disconnector unit 7 is provided with a disconnector and a ground switch, and the cable unit 6 is led out from the disconnector unit 7 via a cable head 52.

  The busbar unit 4 is a three-phase collective type having three-phase main busbar conductors 8a to 8c supported by insulating supports 9a to 9c. Since each phase has substantially the same configuration, an arbitrary one phase will be described. A fixed contact electrode 43 of a disconnector is attached to the conductor 8b, a movable electrode 45 is provided at a predetermined distance from the fixed electrode 43, and a movable contactor that contacts and separates from the fixed electrode 43 while always in contact with the movable electrode 45. The movable contact 44 is configured to be opened and closed by an operation mechanism 47 through an insulator 46. In another embodiment, the bus unit 4 is divided into a bus unit having the main bus conductors 8a to 8c as the center and a disconnect unit having the disconnector as the center, and a gas partition is provided between them by an insulating spacer. Good.

  The circuit breaker unit 10 provided with the vacuum circuit breaker 20 supports the upper and lower portions of the vacuum vessel 13 whose outer surface is covered with the insulating mold member 12 by the insulating support 18, and the fixed side conductor 35 on the fixed electrode 14 side is an insulating spacer. 1 is connected to the fixed-side electrode 53 of the disconnector through a central conductor. The movable rod 25 connected to the movable electrode 15 is led out of the vacuum vessel 13 via the first bellows 21 and is connected to the mechanism portion 31 of the operating device 32 via the insulator 27. The insulating support 18 disposed at the lower part of the vacuum vessel 13 insulates and supports the cylindrical conductor 24 surrounding the vicinity of the first bellows 21, and supports the lower portion of the vacuum vessel 13 through the cylindrical conductor 24. The disconnector unit 70 is connected to the disconnector via the movable conductor 36 and the central conductor of the insulating spacer 2. The movable rod 25 is provided with a current collector 26, and the current collector 26 is electrically connected to the cylindrical conductor 24 by a flexible conductor (not shown). A sealed end lid 23 is connected to the movable rod 25 located in the cylindrical conductor 24, and the lower end of the first bellows 21 is hermetically sealed by the sealed end lid 23. Further, the upper end of the second bellows 22 is hermetically sealed by the hermetic end lid 23, and the lower end of the second bellows 22 is hermetically sealed by the cylindrical conductor 24. Thereby, the inside of the first bellows 21 is the same vacuum as the inside of the vacuum container 13, and an intermediate chamber 24 a is formed between the inside of the cylindrical conductor 24 and the outer periphery of the first bellows 21 and the second bellows 22, and the second The inner side of the bellows 22 is the same gas space as the grounded sealed container 11.

  The disconnector unit 7 provided with a disconnector or a ground switch has a disconnector having the same structure as the disconnector of the bus unit 4, and further includes a movable ground contact 49 and a fixed ground contact 50. And a lightning arrester 51 and the like.

  The cable unit 6 has a cable 53 led out from the disconnector unit 7 through a cable head 52, and a current transformer 54 is provided on the outer periphery of the cable 53.

  In the grounded sealed containers 11, 41, and 48 of each unit, a fluorocarbon gas such as SF6 gas, c-C4F8, CF3SF5, C3F8, and CF3OSF3 is used as a gas mainly composed of dry air or carbon dioxide or nitrogen as an insulating gas. A mixed gas mixed at 20% or less is enclosed.

  c-C4F8, CF3SF5, C3F8, CF3OSF3 and other chlorofluorocarbons are chemically stable substances. Therefore, if the mixing ratio is 20% or more, outgassing during installation inspection work and leakage during long-term operation will occur in the atmosphere. Accumulate in the future and become a global environmental problem in the future. Further, when recovering the gas in the grounded sealed containers 11, 41, 48 by internal inspection or the like, if the gas pressure in those grounded sealed containers is increased, the saturated vapor pressure of c-C4F8, CF3SF5, C3F8, CF3OSF3 is low. For this reason, the liquid is partially liquefied, and separation and recovery are required to manage the mixing ratio, and the recovery apparatus becomes large. Conversely, if the gas pressure during recovery is lowered, the recovery tank will become large. On the other hand, if an insulating gas that does not mix the above-mentioned Freon gas with dry air, nitrogen, or carbon dioxide gas is used, the dielectric strength is less than half that of SF6 gas, so if the pressure is the same, the size of the equipment is more than twice the insulation distance Since the volume is about 8 times or more, the cost is very high. However, these problems are solved by using the mixed gas mixed as described above.

  In addition, since the current interruption performance of these insulating gases is greatly reduced below 30% of SF6 gas, the vacuum circuit breaker 20 is used as a circuit breaker, and a disconnector that requires small current interruption performance such as loop current is disposed. The gas pressure in the grounded sealed containers 41 and 48 is higher than the gas pressure in the grounded sealed container 11 in which the vacuum circuit breaker 20 is disposed.

  Here, the vacuum circuit breaker 20 used to configure the circuit breaker unit 10 has a configuration in which a fixed electrode 14, a movable electrode 15, and a shield 16 are arranged in a ceramic vacuum container 13. Bellows 21 and 22 are used to allow the movable electrode 15 to open and close while maintaining a degree of vacuum. When the pressure difference between the inside and outside of the bellows 21 and 22 is large, the load applied during operation is large and many times. The operation causes fatigue and cracks, making it impossible to maintain the vacuum. For this reason, the pressure difference between the inside and outside of the bellows 21 and 22 needs to be 0.4 MPa or less as much as possible. As a solution to this, it is effective to make the gas pressure in the grounded sealed container 11 in which the vacuum circuit breaker 20 is disposed lower than the gas pressure in the grounded sealed containers 41 and 71 in which the disconnector is disposed as described above. Hereinafter, a configuration that compensates for this point will be described.

  As shown in FIG. 1, a cylindrical conductor 24 is airtightly connected to the lower portion of the vacuum vessel 13, and an upper end of the second bellows 22 is airtightly connected to a sealed end lid 23 that hermetically seals the lower end of the first bellows 21. At the same time, the lower end of the second bellows 22 is airtightly connected to the cylindrical conductor 24. Accordingly, although the vacuum vessel 13 extends to the inside of the first bellows 21, an airtight intermediate chamber 24 a is formed between the inside of the cylindrical conductor 24 and the outer peripheral portions of the bellows 21, 22. In addition, the gas is also separated from the grounded sealed container 11 of the circuit breaker unit 10. The gas pressure applied to the bellows 21 and 22 is sealed by setting the gas pressure in the intermediate chamber 24a to 0.1 to 0.3 MPa · G lower than the gas pressure of the insulating gas sealed in the grounded hermetic container 11. The pressure is set to 0.4 MPa or less.

  Here, if the diameters of the first bellows 21 and the second bellows 22 are substantially equal, the volume of the intermediate chamber 24a can be made unchanged during the opening / closing operation performed by driving the movable rod 25 in the axial direction. No pressure change occurs within 24a. Therefore, the pressure difference during the opening / closing operation is made as small as possible, usually 20% or less, so that there is no significant change in the insulation structure.

FIG. 2 is a cross-sectional view showing a main part of a gas insulated switchgear according to another embodiment of the present invention.
In the embodiment shown in FIG. 1, the operations of the two bellows 21 and 22 are reversed, and the second bellows 22 is compressed when the first bellows 21 is extended. The expansion and compression directions of 21 and 22 may be the same. Here, the cylindrical conductor 24 that is airtightly connected to the lower end of the vacuum vessel 13 has an axial length that does not contact the lower end lid 23 in the open position, and the upper end of the second bellows 22 is airtightly sealed to the lower portion of the cylindrical conductor 24. In addition to being connected, the lower end of the second bellows 22 is airtightly connected to the movable rod 25 or to a fixed member 33 provided with airtightness to the movable rod 25. Therefore, the inside of the first bellows 21 is formed as a part of the vacuum vessel 13, and an intermediate chamber 24 a composed of the inside of the cylindrical conductor 24, the outside of the first bellows 21, and the inside of the second bellows 22 is formed.

  The intermediate chamber 24 a is not part of the vacuum vessel 13 and is also separated from the grounded sealed container 11 of the circuit breaker unit 10, and the insulating pressure in which the gas pressure in the intermediate chamber 24 a is sealed in the grounded sealed vessel 11. The gas pressure applied to the bellows 21 and 22 can be reduced to 0.4 MPa or less by sealing with 0.1 to 0.3 MPa · G lower than the gas pressure of the gas. Again, if the diameters of the first bellows 21 and the second bellows 22 are substantially equal, the volume of the intermediate chamber 24a can be made unchanged during the opening / closing operation performed by driving the movable rod 25 in the axial direction. No pressure change occurs within 24a.

FIG. 3 is a cross-sectional view showing a main part of a gas insulated switchgear according to still another embodiment of the present invention.
In this embodiment, both bellows 21 and 22 shown in FIG. 2 are formed in a conical shape, and both bellows 21 and 22 are formed in a conical shape so that they overlap each other in the axial direction. Therefore, it is possible to reduce the size in the axial direction.

  In each of the above-described embodiments, one intermediate chamber 24a is formed, and the intermediate pressure between the vacuum vessel 13 and the grounded sealed vessel 11 is set, but two or more intermediate chambers are formed using two or more bellows. If the gas pressure is formed and changed stepwise, the gas pressure in the grounded sealed container 11 can be further increased while reducing the burden on the gas pressure of the bellows.

  In this way, by reducing the burden of the gas pressure on the bellows of the vacuum circuit breaker 20, the gas insulated switchgear as shown in FIG. The gas pressure of the insulating gas in the 10 grounded sealed containers 11 is lowered to a gas pressure determined by the mechanical strength of the bellows, and the gas pressure of the insulating gas sealed in the grounded sealed containers 41 and 48 of the other units 4 and 6 is reduced. By increasing the length, the insulation distance of the other units 4 and 6 can be shortened to reduce the size. Moreover, since units 4 and 6 other than the circuit breaker unit 10 include a disconnector, the small current interrupting performance of the disconnector can be improved by increasing the gas pressure. On the other hand, in the grounded sealed container 11 of the circuit breaker unit 10, since an arc is not generated directly in the gas as in the case of a disconnector, etc., the insulation performance is improved by enclosing dry air whose insulation performance is 10 to 20% better than nitrogen. The equipment can be reduced.

  In the gas insulated switchgear shown in FIG. 1, the insulation mold member 12 is molded on the outer peripheral portion of the vacuum vessel 13 in the vacuum circuit breaker 20 to improve the grounding and interphase dielectric strength of the vacuum circuit breaker 20. The insulating mold member 12 may be applied to the intermediate chamber 24a. The insulating mold member 12 may be applied including the ceramic portion in the ceramic vacuum vessel 13, but may be applied only to the metal portion.

FIG. 4 is a cross-sectional view showing a main part of a gas-insulated switchgear according to still another embodiment of the present invention, and the same components as those of the previous embodiment are denoted by the same reference numerals and detailed description thereof is omitted. .
In this embodiment, an insulating tube 29 that is airtightly connected to the lower end of the vacuum vessel 13 is provided, and the lower end portion of the insulating tube 29 is airtightly connected to the grounded hermetic vessel 11. The insulating cylinder 29 may be one in which the cylindrical conductor 24 serving as a connection portion with the movable high-voltage conductor 36 is integrally provided on the upper portion thereof, but the upper portion thereof is airtightly connected to the lower portion of the cylindrical conductor 24. May be. The movable rod 25 having the movable electrode 15 can be opened and closed in the axial direction while maintaining the degree of vacuum in the vacuum vessel 13 by the first bellows 21, and the rod portion 37 connected to the lower end portion of the movable rod 25 via the insulator 2. The second bellows 22 is arranged on the rod portion 37 led out to the grounded sealed container 11. The rod portion 37 led out by the second bellows 22 is connected to the operating device 32 and the mechanism portion 31 of the vacuum circuit breaker 20 arranged outside the grounded sealed container 11.

  The second bellows 22 has an upper end connected to the rod portion 37 in an airtight manner by an end lid 34 and a lower end connected to the grounded sealed container 11 in an airtight manner. Accordingly, an intermediate chamber 24a divided by both bellows 21 and 22 is formed in the insulating cylinder 29, and this intermediate chamber 24a can be set to an intermediate gas pressure between the vacuum vessel 13 and the atmosphere. The intermediate chamber 24a in the previous embodiment has an intermediate gas pressure between the inside of the vacuum vessel 13 and the grounded sealed vessel 11, but here it can be set to an intermediate gas pressure in the vacuum vessel 13 and in the atmosphere. . This is irrelevant to the gas pressure in the grounded sealed container 11 from the viewpoint of the burden due to the difference in gas pressure between the inside and outside of the bellows 21 and 22, so the gas pressure in the grounded sealed container 11 is changed to the both bellows 21 and 22 It means that it can be set independently.

  According to such a gas insulated switchgear, the insulating gas in the grounded sealed container 11 in which the vacuum circuit breaker 20 is disposed, and the grounded sealed containers 41 and 48 in which the disconnector is disposed, and the gas pressure thereof are both bellows 21. , 22 can be selected under optimum conditions regardless of the burden caused by the difference in gas pressure between the inside and outside, so that a gas insulated switchgear having a smaller size and more stable performance can be obtained. Compared to the gas insulated switchgear shown in FIG. 1, the gas pressure in the grounded sealed container 11 in FIG. Further, in terms of the dielectric strength of the insulating gas in the grounded sealed container 11, the same effect as that obtained by increasing the gas pressure in the grounded sealed container 11 of FIG. 1 can be obtained.

FIG. 5 is a cross-sectional view showing a main part of a gas-insulated switchgear according to still another embodiment of the present invention, and the same reference numerals are given to the equivalents of the embodiment shown in FIG. Is omitted.
In this embodiment, an insulating tube 29 that is airtightly connected to the lower end of the vacuum vessel 13 is provided, and the lower end portion of the insulating tube 29 is airtightly connected to the grounded hermetic vessel 11. The insulating cylinder 29 may be one in which the cylindrical conductor 24 serving as a connection portion with the movable high-voltage conductor 36 is integrally provided on the upper portion thereof, but the upper portion thereof is airtightly connected to the lower portion of the cylindrical conductor 24. May be. In any case, the bellows is omitted between the vacuum vessel 13 and the insulating cylinder 29, and both communicate with each other to form an integral vacuum vessel. The movable rod 25 having the movable electrode 15 is connected to the rod portion 37 via the insulator 27 in this integral vacuum container, and then led out of the grounded sealed container 11. A first bellows 21 is provided at the lead-out portion to the outside of the grounded sealed container 11, and the first bellows 21 can be opened and closed in the axial direction while maintaining the degree of vacuum in the integral vacuum container. The rod portion 37 led out by the first bellows 21 is connected to the operating device 32 and the mechanism portion 31 of the vacuum circuit breaker 20 disposed outside the grounded sealed container 11.

  The upper end of the first bellows 21 is airtightly connected to the rod portion 37 by the end lid 34, and the lower end of the first bellows 21 is airtightly connected to the grounded sealed container 11. Therefore, only the first bellows 21 separates the degree of vacuum in the integrated vacuum vessel 13 and the atmosphere outside the grounded sealed vessel 11. Here, although there is no intermediate chamber 24a in the previous embodiment, only the pressure difference between the integrated vacuum vessel 13 and the atmosphere is applied to the first bellows 21. The burden caused by is reduced. Moreover, since the gas pressure in the grounded sealed container 11 and the burden due to the gas pressure difference between the inside and outside of the first bellows 21 are irrelevant, the gas pressure in the grounded sealed container 11 can be determined by a desired dielectric strength.

  According to such a gas-insulated switchgear, the insulating bellows in the grounded sealed container 11 in which the vacuum circuit breaker 20 is disposed, and the grounded sealed containers 41 and 71 in which the disconnectors are disposed, and the gas pressure are supplied to the first bellows. Since the selection can be made under optimum conditions regardless of the load caused by the difference in gas pressure between the inside and outside of the gas chamber 21, the gas insulated switchgear having a smaller size and more stable performance can be obtained as in the case of the previous embodiment.

  As described above, the gas-insulated switchgear according to the present invention includes the insulating gas in the grounded sealed container 11 in which the vacuum circuit breaker 20 is disposed, the grounded sealed containers 41 and 48 in which the disconnectors are disposed, and the gas pressure thereof. Regardless of the burden caused by the gas pressure difference between the inside and outside of the bellows 22, each can be selected under optimum conditions, and the pressure difference applied to the bellows 22 is the pressure difference between the degree of vacuum in the vacuum vessel and the atmosphere, so it is compact. Thus, a gas insulated switchgear having more stable performance can be obtained. Moreover, since only one bellows is used, the configuration is simplified.

  Moreover, the gas insulated switchgear of the present invention can limit the use of SF6 gas with a high global warming potential because the gas pressure in the grounded sealed container containing the vacuum circuit breaker can be made higher than the limit due to the strength of the bellows. However, it is possible to improve the dielectric strength, thereby reducing the environmental load and reducing the cost to the same level as in the past.

It is sectional drawing which shows the gas insulated switchgear by one embodiment of this invention. It is sectional drawing which shows the principal part of the gas insulated switchgear by other embodiment of this invention. It is sectional drawing which shows the principal part of the gas insulated switchgear by other embodiment of this invention. It is sectional drawing which shows the principal part of the gas insulated switchgear by other embodiment of this invention. It is sectional drawing which shows the gas insulated switchgear by one embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 Insulation spacer 4 Bus side side disconnector unit 7 Disconnector unit 10 Circuit breaker unit 11 Grounding airtight container 12 Vacuum container 20 Vacuum circuit breaker 22 Bellows 29 Insulating cylinder 41, 48 Grounding airtight container

Claims (1)

A circuit breaker unit and a disconnector unit are constructed by insulating and supporting the high-voltage conductor that constitutes the main circuit in a grounded sealed container filled with an insulating gas. The circuit breaker unit maintains the degree of vacuum in the vacuum container. In the gas insulated switchgear constituted by a vacuum circuit breaker having a first bellows that allows the movable electrode to be opened and closed, the grounded sealed container is divided into two or more gas compartments by an insulating spacer, and one of the gas compartments The vacuum circuit breaker is arranged to constitute the circuit breaker unit, the disconnector is arranged in the other gas compartment to constitute the disconnector unit, and one end of the vacuum vessel is hermetically connected, and An insulating cylinder having the other end hermetically connected to the grounded airtight container is provided, the inside of the insulating cylinder communicates with the inside of the vacuum container, and the vacuum container, the inside of the insulating cylinder and the atmosphere are connected to the other end of the insulating cylinder. Inside and By dividing between gas insulated switchgear, characterized in that provided with the first bellows.

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