Vacuum circuit breaker

Abstract

A vacuum circuit breaker (100) is provided with: a vacuum valve (1) provided with bellows (2); a tank (5) that houses the vacuum valve (1); flanges that are attached to the opening of the tank (5) and form a space in which a high-pressure insulating gas is sealed; and an operation mechanism (6) that is installed outside the tank (5) and operates the opening / closing of the vacuum valve (1). The flanges include a first flange (3A) located on the atmosphere side outside the tank (5), and a second flange (3B) located on the insulating gas side inside the tank (5). An intermediate chamber (4) is formed between the first flange (3A) and the second flange (3B), and the vacuum valve (1) is fixed to the second flange (3B) via an insulating cylinder (7). The intermediate chamber (4), the inside of the insulating cylinder (7), and the inside of the bellows (2) of the vacuum valve (1) communicate with one another, and the pressure is set to an intermediate level between the gas pressure of the insulating gas and the atmospheric pressure.

Description

Vacuum circuit breaker

[0001] The present disclosure relates to a vacuum interrupter.

[0002] In recent years, due to environmental considerations, there has been a shift in insulating gas from SF6 (sulfur hexafluoride) gas to gases with lower environmental impact, such as gases with lower global warming potential (GWP). When changing the gas sealed inside the tank to one with lower environmental impact, it is necessary to increase the gas pressure to obtain the same voltage resistance performance as SF6 gas. In this case, there is a risk that the bellows in the moving part of the vacuum valve may be deformed or damaged due to the pressure difference between the high gas pressure inside the tank and the vacuum inside the vacuum valve.

[0003] To solve this problem, a gas-insulated switchgear has been disclosed that uses two bellows to reduce the load on the bellows by adopting a double pressure structure.

[0004] Japanese Patent Application Laid-Open No. 2004-236455

[0005] However, in the device described in the patent document, the space formed by the two bellows is sealed off, making it difficult to fill and replenish the gas. In addition, high gas pressure causes significant deformation of the vacuum bellows and the flange to which the operating mechanism is fixed, which may adversely affect the alignment (centering) of the entire vacuum circuit breaker.

[0006] The present disclosure discloses a technology for solving the above-mentioned problems, and provides a vacuum circuit breaker having a structure that suppresses deformation of the flange and bellows due to pressure sharing and allows gas to be sealed and replenished.

[0007] The vacuum circuit breaker of the present disclosure comprises a vacuum valve with a bellows for maintaining a vacuum, a tank for housing the vacuum valve, a flange attached to the opening of the tank to form a space for sealing high-pressure insulating gas, and an operating mechanism installed outside the tank for opening and closing the vacuum valve, wherein the flange consists of a first flange on the atmospheric side outside the tank and a second flange on the insulating gas side inside the tank, and an intermediate chamber is formed between the first flange and the second flange, and the vacuum valve is fixed to the second flange via an insulating tube, and the intermediate chamber, the inside of the insulating tube, and the inside of the bellows of the vacuum valve are connected to create a pressure intermediate between the gas pressure of the insulating gas and atmospheric pressure.

[0008] According to the vacuum circuit breaker of the present disclosure, it is possible to obtain a vacuum circuit breaker that suppresses deformation of the flange and bellows due to pressure sharing and realizes a structure that allows gas to be sealed and replenished.

[0009] FIG. 1 is a cross-sectional view of a vacuum circuit breaker according to embodiment 1. FIG. 2 is a detailed view of an airtight drive unit of the vacuum circuit breaker according to embodiment 1. FIG. 3 is a side view of a vacuum circuit breaker according to embodiment 1. FIG. 4 is a cross-sectional view of a vacuum circuit breaker according to embodiment 2. FIG. 5 is a cross-sectional view of a vacuum circuit breaker according to embodiment 3. FIG. 6 is a detailed view of an airtight drive unit of the vacuum circuit breaker according to embodiment 3. FIG. 7 is a cross-sectional view of a vacuum circuit breaker according to embodiment 4. FIG. 8 is a detailed view of an airtight drive unit of the vacuum circuit breaker according to embodiment 4. FIG. 9 is a cross-sectional view of a vacuum circuit breaker according to embodiment 5. FIG. 10 is a detailed view of an airtight drive unit of the vacuum circuit breaker according to embodiment 5. FIG. 11 is a cross-sectional view of a vacuum circuit breaker according to embodiment 6. FIG. 12 is a cross-sectional view of a vacuum circuit breaker according to embodiment 7. FIG. 13 is a detailed view of an airtight drive unit of the vacuum circuit breaker according to embodiment 7.

[0010] Embodiment 1. Embodiment 1 relates to a vacuum circuit breaker comprising a vacuum valve, a tank for accommodating the vacuum valve, a flange attached to the opening of the tank to form a space for sealing high-pressure insulating gas, and an operating mechanism for opening and closing the vacuum valve. The flanges are composed of a first flange on the atmosphere side outside the tank and a second flange on the insulating gas side inside the tank. An intermediate chamber is formed between the first and second flanges, and the vacuum valve is fixed to the second flange via an insulating cylinder. The intermediate chamber, the interior of the insulating cylinder, and the interior of the bellows of the vacuum valve are in communication with each other, and the pressure is intermediate between the insulating gas pressure and atmospheric pressure. This disclosure will sequentially describe the vacuum circuit breaker, which is a main component of gas-insulated switchgear. Embodiment 1 describes a vacuum circuit breaker compatible with a three-phase AC power source, and Embodiment 6 will describe a vacuum circuit breaker compatible with a single-phase AC power source.

[0011] A vacuum circuit breaker according to a first embodiment will be described below with reference to Fig. 1, which is a cross-sectional view of the vacuum circuit breaker, Fig. 2, which is a detailed view of the airtight drive unit of the vacuum circuit breaker, and Fig. 3, which is a side view of the vacuum circuit breaker. In each figure, identical or corresponding parts are designated by the same reference numerals, and duplicated explanations will be omitted. In the following description, the up-down direction in Fig. 1 is the Z direction, the left-right direction is the X direction, and the front-back direction is the Y direction, and the directions of the arrows are the positive sides. This also applies to the subsequent descriptions of the drawings.

[0012] First, the configuration and function of a vacuum circuit breaker 100 according to a first embodiment will be described with reference to Figures 1 to 3. Figure 2 shows details of the airtight drive unit, which is a main part of the vacuum circuit breaker 100. Here, the airtight drive unit refers to the space inside the tank 5 where the vacuum valve 1 is installed and where insulating gas is sealed. Figure 3 is a side view of the vacuum circuit breaker 100 as viewed from the right side of Figure 1, i.e., from the positive side to the negative side in the X direction.

[0013] The vacuum circuit breaker 100 comprises, as its main components, a vacuum valve 1, a tank 5 in which the vacuum valve 1 is installed and an insulating gas is sealed inside, a first flange 3A that is installed at the upper opening of the tank 5 to fix the vacuum valve 1 and seal the insulating gas, and an operating mechanism 6 that opens and closes the vacuum valve 1.

[0014] To enable multiple vacuum circuit breakers 100 to be arranged side by side in a panel configuration, the tank 5 contains the vacuum interrupters 1 as well as the movable connecting conductors 8, movable bus conductors 9, fixed bus conductors 10, and fixed connecting conductors 11 for connecting to other panels. Since the first embodiment is a three-phase vacuum circuit breaker, three vacuum interrupters 1, three movable connecting conductors 8, three movable bus conductors 9, three fixed bus conductors 10, and three fixed connecting conductors 11 are contained in the tank 5. In FIG. 3 , the three vacuum interrupters 1, the movable connecting conductors 8, and the movable bus conductors 9 are visible from the front through the opening for the side-by-side panel configuration. In this specification, the side of the vacuum interrupter 1 where the movable contacts are located (positive side in the Z direction in FIG. 1 ) is referred to as the movable side, and the side of the vacuum interrupter 1 where the fixed contacts are located (negative side in the Z direction in FIG. 1 ) is referred to as the fixed side.

[0015] In addition, to shorten the insulation distance, a first flange 3A is installed at the upper opening of the tank 5, the tank 5 is sealed, and a gas with excellent insulating properties (dry air, etc.) is sealed inside. To insulate the three-phase vacuum valve 1 from the grounded tank 5, the movable side (positive side in the Z direction in Figure 1) is fixed to the tank 5 via an insulating cylinder 7, and the fixed side (negative side in the Z direction in Figure 1) is fixed to the tank 5 via a supporting insulator 12.

[0016] 1, a gas pipe 16 for supplying low-pressure gas to the intermediate chamber 4 (described later) is installed on the first flange 3A at the upper opening of the tank 5. This low-pressure gas has a pressure intermediate between the pressure of the high-pressure insulating gas and the vacuum of the vacuum valve 1, and it is desirable to use a gas with excellent insulating properties. In addition, the operating mechanism 6 has a three-phase branch section 6a for opening and closing the three vacuum valves 1.

[0017] 2 shows details of the airtight drive unit, which is a feature of the vacuum circuit breaker 100. In order to separate a high-pressure space filled with a gas having excellent insulating properties from a low-pressure space, a double structure is formed by a first flange 3A and a second flange 3B, forming a low-pressure intermediate chamber 4 and separating the gas compartments. When the first flange 3A and the second flange 3B are collectively referred to, they will be referred to as flange 3.

[0018] In Figure 2, the high-pressure space (space H) is shown as a solid line with widely spaced diagonal lines extending from the upper right to the lower left, the low-pressure space (space L) is shown as a solid line with diagonal lines extending from the upper right to the lower left, and the vacuum space (space V) is shown as a solid line with diagonal lines extending from the upper left to the lower right. The pressure outside the tank 5 is atmospheric.

[0019] Airtightness is maintained at the boundary surfaces of the gas compartments by using either fixed seals or sliding seals. In this specification, a sliding seal refers to a structure in which a seal member comes into contact with a sliding portion and the contact portion changes, while a fixed seal refers to a structure in which the contact portion of the seal member does not change, such as a bolt fastening portion. A sliding seal 14 is used at the contact portion between the operating mechanism 6 and the first flange 3A of the vacuum circuit breaker 100, so that airtightness is not impaired by opening and closing operations. As an example of a fixed seal, a fixed seal is used at the contact portion between the gas pipe 16 and the first flange 3A, so that airtightness is maintained.

[0020] Both the fixed seal and the sliding seal use an O-ring or the like as a sealing member. Unlike the sliding seal, the fixed seal does not have a separate part, but is constructed by, for example, drilling a groove in the first flange 3A and inserting a sealing member into this groove, and therefore is not shown in the drawings.

[0021] 2, the insulating tube 7 is composed of an insulator 7a, a filler metal 7b, and a filler metal 7c. The filler metal 7b is a member for fixing the second flange 3B to the insulating tube 7, and has a tap for fixing on the filler metal 7b side and an O-ring for sealing. The filler metal 7c is a member for fixing the movable-side connecting conductor 8 to the insulating tube 7, and has a tap for fixing on the filler metal 7c side and an O-ring for sealing.

[0022] 2, a low-pressure space (space L) is formed by the intermediate chamber 4, the inside of the insulating tube 7, the inside of the movable-side connecting conductor 8, and the inside of the bellows 2. Therefore, the inside of the bellows 2 communicates with the intermediate chamber 4 and is under low pressure, while the outside of the bellows 2 is a vacuum.

[0023] Now, Fig. 3 will be described. Since the first embodiment is a vacuum circuit breaker 100 compatible with a three-phase AC power supply, three vacuum valves 1, three movable-side connecting conductors 8, three movable-side bus conductors 9, three fixed-side bus conductors 10, and three fixed-side connecting conductors 11 are stored inside the tank 5. Because Fig. 3 is a right side view of Fig. 1, the fixed-side bus conductors 10 and the fixed-side connecting conductors 11 are hidden from view through the opening for the side-by-side panels on the front of the tank 5.

[0024] Next, we will explain the effect of providing a low-pressure space (space L) in the airtight drive section, which is a feature of the vacuum circuit breaker 100. The low-pressure intermediate chamber 4 is provided by forming a dual-layer structure between the first flange 3A and the second flange 3B. This intermediate chamber 4 is connected to the inside of the insulating tube 7, the inside of the movable-side connecting conductor 8, and the inside of the bellows 2, forming a low-pressure space (space L). If this low-pressure space L were not provided, the first flange 3A would be subjected to a pressure difference between the high pressure of the insulating gas and atmospheric pressure. Furthermore, the bellows 2 would be subjected to a pressure difference between the high pressure of the insulating gas and the vacuum of the vacuum valve 1. Providing this low-pressure space L can reduce the pressure difference between the high pressure of the insulating gas applied to the first flange 3A and atmospheric pressure. Furthermore, it can also reduce the pressure difference between the high pressure of the insulating gas applied to the bellows 2 and the vacuum of the vacuum valve 1.

[0025] Furthermore, if the low-pressure space L is not provided, the bellows 2 would be affected by the high-pressure insulating gas. However, by providing the low-pressure space L, the inside of the bellows 2 is subjected to the low pressure of the space L, not the high pressure of the insulating gas. This allows the bellows 2 to use components that are difficult to use under high gas pressure, thereby broadening the range of component selection. Furthermore, if the low-pressure space L is not provided, the first flange 3A would be affected by the high-pressure insulating gas. However, by providing the low-pressure space L, the inside of the first flange 3A is subjected to the low pressure of the intermediate chamber 4, not the high pressure of the insulating gas. This suppresses deformation of the first flange 3A, which occurs in flanges of conventional configurations, and facilitates alignment (centering) of the entire vacuum circuit breaker. Furthermore, the differential pressure acting on the first flange 3A is reduced, allowing the strength of the first flange 3A to be reduced, thereby achieving cost and weight reductions.

[0026] Furthermore, in the vacuum circuit breaker 100 of the first embodiment, the intermediate chamber 4 is common to each of the three phases and communicates with the inside of the insulating cylinder 7, the movable-side connecting conductor 8, and the bellows 2 of each phase to form the low-pressure space L. Therefore, when low-pressure gas is supplied to the low-pressure space L, it is not necessary to branch the gas to each phase, and gas can be charged and replenished using a single gas pipe 16.

[0027] As explained above, the vacuum circuit breaker of the first embodiment provides a low-pressure space between the high pressure of the insulating gas and the vacuum, thereby realizing a structure that suppresses deformation of the flange and bellows due to pressure sharing and enables gas charging and replenishment. Furthermore, gas can be charged and replenished to this three-phase low-pressure space using a single gas pipe.

[0028] Second Embodiment In the second embodiment, the movable side of the vacuum valve is installed in the lower part of the tank.

[0029] A vacuum circuit breaker according to the second embodiment will be described, focusing on the differences from the first embodiment, based on Fig. 4, which is a cross-sectional view of the vacuum circuit breaker. In the configuration diagram of the second embodiment, parts that are the same as or equivalent to those in the first embodiment are given the same reference numerals. In order to distinguish the second embodiment from the first embodiment, the second embodiment is referred to as a vacuum circuit breaker 200.

[0030] As shown in FIG. 4 , in a vacuum circuit breaker 200 of the second embodiment, a first flange 3A and a second flange 3B, to which the movable side of a vacuum interrupter 1 is fixed via an insulating tube 7, are fixed to the bottom surface of a tank 5. The fixed side of the vacuum interrupter 1 (the positive side in the Z direction in FIG. 4 ) is fixed to the top surface of the tank 5 via a support insulator 12. An operating mechanism 6 for opening and closing the vacuum interrupter 1 and a three-phase branch section 6a are also installed on the lower side of the tank 5. The installation directions (Z direction) of the bellows 2, movable side connecting conductor 8, and fixed side connecting conductor 11 are opposite to those in FIG. 1 . Note that, for clarity, the movable side bus conductor 9 and the fixed side bus conductor 10 are omitted in FIG. 4 . The remaining configuration is the same as that of the first embodiment, and therefore description thereof will be omitted.

[0031] Next, the features of the vacuum circuit breaker 200 of the second embodiment will be described. In the second embodiment, the vacuum valve 1 is attached to the bottom of the tank 5, and the intermediate chamber 4 is located on the bottom side of the tank 5 (negative side in the Z direction). However, as in the first embodiment, the intermediate chamber 4 is common to each of the three phases and communicates with the inside of the insulating tube 7, the movable-side connecting conductor 8, and the bellows 2 of each phase to form the low-pressure space L. Therefore, when supplying low-pressure gas to the low-pressure space L, a single gas pipe 16 can be used for gas charging and replenishment without requiring branching to each phase. Also, as in the first embodiment, the formation of the first flange 3A, the second flange 3B, and the intermediate chamber 4 share the pressure difference, suppressing deformation that occurs in conventional flanges and facilitating alignment (centering) of the entire vacuum circuit breaker. Furthermore, in the second embodiment, because the movable side of the vacuum valve 1 is located on the bottom side of the tank 5, gravity acts on the drive rod, which moves downward in the Z direction, during interruption of an abnormal current, thereby increasing the opening speed of the vacuum circuit breaker.

[0032] As explained above, the vacuum circuit breaker of the second embodiment provides a low-pressure space between the high pressure of the insulating gas and the vacuum, thereby realizing a structure that suppresses deformation of the flange and bellows by sharing the pressure and enables gas charging and replenishment. Furthermore, gas can be charged and replenished in this three-phase low-pressure space using a single gas pipe. Furthermore, the opening speed of the vacuum circuit breaker is increased when interrupting an abnormal current.

[0033] Third Embodiment In a third embodiment, the contact portion between the operating mechanism of the vacuum circuit breaker and the opening of the first flange is configured to maintain airtightness by a bellows.

[0034] The vacuum circuit breaker of embodiment 3 will be described, focusing on the differences from embodiment 1, with reference to Fig. 5, which is a cross-sectional view of the vacuum circuit breaker, and Fig. 6, which is a detailed view of the airtight drive unit of the vacuum circuit breaker. In the configuration diagram of embodiment 3, parts that are the same as or equivalent to those of embodiment 1 are given the same reference numerals. In order to distinguish embodiment 3 from embodiment 1, embodiment 3 is referred to as vacuum circuit breaker 300.

[0035] In the vacuum circuit breaker 300 of the third embodiment, the contact portion between the operating mechanism 6 and the opening of the first flange 3A is maintained in airtightness by the bellows 21. The bellows 21 has a bellows body 21a brazed to a bellows mounting flange 21b, which is fixed to the first flange 3A. A fixed seal is used at the boundary between the first flange 3A and the bellows mounting flange 21b to maintain airtightness. The other configurations are the same as those of the first embodiment, and therefore description thereof will be omitted.

[0036] Next, the features of the vacuum circuit breaker 300 of the third embodiment will be described. In the third embodiment, airtightness is maintained by connecting the contact portion between the operating mechanism 6 of the vacuum valve 1, which slides during the opening and closing operations of the vacuum circuit breaker 300, and the opening of the first flange 3A with a bellows 21. Because the bellows can expand and contract, airtightness can be maintained, similar to the sliding seal used in the first embodiment, even during opening and closing operations. Furthermore, when a sliding seal is used, a fixed seal comes into contact with the sliding portion during the opening and closing operations, which may cause wear to the fixed seal. However, when the bellows 21 is used, a fixed seal can be used at the boundary between the first flange 3A and the bellows mounting flange 21b, eliminating the risk of wear to the fixed seal due to sliding.

[0037] As described above, the vacuum circuit breaker of embodiment 3 provides a low-pressure space between the high pressure of the insulating gas and the vacuum, thereby realizing a structure that suppresses deformation of the flange and bellows due to pressure sharing and enables gas charging and replenishment. Furthermore, gas can be charged and replenished to this three-phase low-pressure space using a single gas pipe. In addition, it is possible to eliminate the risk of wear on the fixed seal at the contact point between the vacuum valve operating mechanism and the opening of the first flange.

[0038] Fourth Embodiment In a fourth embodiment, a three-phase branch portion of an operating mechanism of a vacuum circuit breaker is housed in an intermediate chamber formed by a first flange and a second flange.

[0039] The vacuum circuit breaker of embodiment 4 will be described, focusing on the differences from embodiment 1, based on Fig. 7, which is a cross-sectional view of the vacuum circuit breaker, and Fig. 8, which is a detailed view of the airtight drive unit of the vacuum circuit breaker. In the configuration diagram of embodiment 4, parts that are the same as or equivalent to those of embodiment 1 are given the same reference numerals. In order to distinguish from embodiment 1, embodiment 4 is referred to as a vacuum circuit breaker 400 and a three-phase branch unit 6b.

[0040] 7 and 8, in a vacuum circuit breaker 400 according to the fourth embodiment, a three-phase branch portion 6b of an operating mechanism 6 is installed in an intermediate chamber 4 formed by a first flange 3A and a second flange 3B. The other configuration is the same as that of the first embodiment, and therefore a description thereof will be omitted.

[0041] Next, a description will be given of the features of the vacuum circuit breaker 400 according to the fourth embodiment. In the fourth embodiment, the three-phase branch portion 6b of the operating mechanism 6 of the vacuum circuit breaker 400 is installed in the intermediate chamber 4, so that the contact portion between the operating mechanism 6 and the first flange 3A can be kept airtight with a single sliding seal 14. Since the number of locations where gas sealing is required is reduced, it is possible to reduce costs and improve leak resistance while maintaining airtightness.

[0042] As described above, the vacuum circuit breaker of embodiment 4 provides a low-pressure space between the high pressure of the insulating gas and the vacuum, thereby realizing a structure that suppresses deformation of the flange and bellows due to pressure sharing and enables gas charging and replenishment. Furthermore, gas can be charged and replenished to this three-phase low-pressure space using a single gas pipe. In addition, costs can be reduced and leak resistance can be improved.

[0043] Fifth Embodiment In the fifth embodiment, the second flange and the insulating cylinder are integrally molded to form an insulating flange.

[0044] The vacuum circuit breaker of embodiment 5 will be described, focusing on the differences from embodiment 1, with reference to Fig. 9, which is a cross-sectional view of the vacuum circuit breaker, and Fig. 10, which is a detailed view of the airtight drive unit of the vacuum circuit breaker. In the configuration diagram of embodiment 5, parts that are the same as or equivalent to those of embodiment 1 are given the same reference numerals. In order to distinguish embodiment 5 from embodiment 1, embodiment 5 is referred to as vacuum circuit breaker 500.

[0045] In embodiment 5, the second flange 3B and insulating tube 7 in embodiment 1 are integrally molded as an insulator flange 22. The first flange 3A and the integrally molded insulator flange 22 form an intermediate chamber 4. In FIG. 10, the insulator flange 22 is composed of an insulator 22a and a filler metal 22b. The filler metal 22b is a member for fixing the movable-side connecting conductor 8 to the insulator flange 22, and a tap for fixing is cut on the filler metal 22b side, and an O-ring for sealing is installed. The other configuration is the same as in embodiment 1 above, so a description thereof will be omitted.

[0046] Next, the features of the vacuum circuit breaker 500 of the fifth embodiment will be described. In the fifth embodiment, the function of the second flange 3B, which forms the intermediate chamber 4 together with the first flange 3A, and the function of the insulating tube 7, which ensures insulation between the movable-side connecting conductor 8, which is the live part, and the tank 5, are integrated by being molded as an insulator flange 22. As a result, the number of parts can be reduced. By reducing the number of parts, the number of locations where gas sealing is performed is reduced (specifically, the filler metal 7b in FIG. 2 is unnecessary), and therefore, leak performance can be improved while maintaining airtightness.

[0047] As described above, the vacuum circuit breaker of embodiment 5 provides a low-pressure space between the high pressure of the insulating gas and the vacuum, thereby realizing a structure that suppresses deformation of the flange and bellows due to pressure sharing and enables gas charging and replenishment. Furthermore, gas can be charged and replenished to this three-phase low-pressure space using a single gas pipe. In addition, the number of parts can be reduced and leak resistance can be improved.

[0048] Sixth Embodiment The sixth embodiment is a single-phase vacuum circuit breaker.

[0049] The vacuum circuit breaker of embodiment 6 will be described with reference to Fig. 11, which is a cross-sectional view of the vacuum circuit breaker, focusing on the differences from embodiment 1. In the configuration diagram of embodiment 5, parts that are the same as or equivalent to those of embodiment 1 are given the same reference numerals. In order to distinguish embodiment 6 from embodiment 1, embodiment 6 is referred to as a vacuum circuit breaker 600.

[0050] Embodiment 6 is a single-phase vacuum circuit breaker in which one vacuum interrupter 1 is housed in a tank 5. As in embodiment 1, a double structure is formed by a first flange 3A and a second flange 3B to provide an intermediate chamber 4, and a low-pressure space (space L) is formed by communicating this intermediate chamber 4 with the inside of an insulating cylinder 7, the inside of a movable-side connecting conductor 8, and the inside of a bellows 2. Since the configuration is the same as embodiment 1 except for the fact that one vacuum interrupter 1 is housed in a tank 5, a description thereof and a detailed diagram of the airtight drive unit are omitted.

[0051] Next, the features of the single-phase vacuum circuit breaker 600 of the sixth embodiment will be described. By providing the low-pressure space L, it is possible to reduce the pressure difference between the high pressure of the insulating gas applied to the first flange 3A and atmospheric pressure. It is also possible to reduce the pressure difference between the high pressure of the insulating gas applied to the bellows 2 and the vacuum of the vacuum valve 1. Furthermore, it is possible to fill and replenish gas in the low-pressure space L through the gas pipe 16.

[0052] As described above, the single-phase vacuum circuit breaker of embodiment 6 has a low-pressure space intermediate between the high pressure of the insulating gas and the vacuum, thereby realizing a structure that suppresses deformation of the flange and bellows due to pressure sharing and enables gas to be sealed and replenished.

[0053] Seventh Embodiment In a seventh embodiment, an intermediate chamber is provided outside the tank.

[0054] The vacuum circuit breaker of embodiment 7 will be described, focusing on the differences from embodiment 1, with reference to Fig. 12, which is a cross-sectional view of the vacuum circuit breaker, and Fig. 13, which is a detailed view of the airtight drive unit of the vacuum circuit breaker. In the configuration diagram of embodiment 5, parts that are the same as or equivalent to those of embodiment 1 are given the same reference numerals. In order to distinguish embodiment 7 from embodiment 1, the parts are referred to as a vacuum circuit breaker 700, a third flange 31A, and a fourth flange 31B.

[0055] As shown in Figure 12, in embodiment 7, the first flange 3A in embodiment 1 is fixed to the tank 5 as a fourth flange 31B using a flat flange plate. The vacuum valve 1 is fixed to the fourth flange 31B via an insulating cylinder 7. The second flange 3B in embodiment 1 is fixed to the fourth flange 31B as a third flange 31A, thereby providing an intermediate chamber 4 outside the tank 5. The third flange 31A and the fourth flange 31B form a double structure to provide the intermediate chamber 4, which communicates with the inside of the insulating cylinder 7, the inside of the movable-side connecting conductor 8, and the inside of the bellows 2 to form a low-pressure space (space L). The remaining configuration is the same as in embodiment 1, and therefore description thereof will be omitted.

[0056] Next, the features of the vacuum circuit breaker 700 of the seventh embodiment will be described. In the seventh embodiment, the fourth flange 31B fixed to the tank 5 and the third flange 31A fixed to the fourth flange 31B form the intermediate chamber 4 outside the tank 5, thereby reducing the pressure difference between the high pressure of the insulating gas and the atmospheric pressure and the vacuum inside the vacuum valve 1. Furthermore, gas charging and replenishment can be facilitated using a single gas pipe 16 that does not require branching. Compared to the first flange 3A of the first embodiment, the fourth flange 31B, to which the vacuum valve 1 and other components are fixed, requires a greater thickness to withstand high mechanical shocks and high pressures. However, since the third flange 31A is only subjected to the low pressure of the intermediate chamber 4, it can be thinned to a thickness sufficient to maintain the seal. Furthermore, since the intermediate chamber 4 is formed outside the tank 5, the height dimension of the tank 5 can be reduced.

[0057] In the seventh embodiment, the fourth flange 31B is fixed to the tank 5 as a flat flange plate, and the third flange 31A is fixed to this fourth flange 31B, thereby providing the intermediate chamber 4 outside the tank 5. By providing the intermediate chamber 4 outside the tank 5, the height of the tank 5 is lowered. As a method of providing the intermediate chamber 4 outside the tank 5, for example, in the first embodiment, the second flange 3B is provided at the opening of the tank 5 as a flat flange plate, and the first flange 3A, which has a convex shape at the top, is provided on top of the second flange 3B, thereby providing the intermediate chamber 4 outside the tank 5.

[0058] As explained above, the vacuum circuit breaker of embodiment 7 provides a low-pressure space between the high pressure of the insulating gas and the vacuum, thereby realizing a structure that suppresses deformation of the flange and bellows due to pressure sharing and enables gas charging and replenishment. Furthermore, gas can be charged and replenished to this three-phase low-pressure space using a single gas pipe. In addition, the height of the tank can be reduced.

[0059] Although various exemplary embodiments and examples are described in this disclosure, the various features, aspects, and functions described in one or more embodiments are not limited to the application of a particular embodiment, but may be applied to the embodiments alone or in various combinations. Therefore, countless variations not illustrated are anticipated within the scope of the technology disclosed in this specification. For example, this includes cases where at least one component is modified, added, or omitted, or where at least one component is extracted and combined with components of another embodiment.

[0060] REFERENCE SIGNS LIST 1 vacuum valve, 2 bellows, 3A first flange, 3B second flange, 4 intermediate chamber, 5 tank, 6 operating mechanism, 6a, 6b three-phase branch section, 7 insulating tube, 7a insulator, 7b filler metal, 7c filler metal, 8 movable side connecting conductor, 9 movable side bus conductor, 10 fixed side bus conductor, 11 fixed side connecting conductor, 12 support insulator, 14 sliding seal, 16 gas piping, 21 bellows, 21a bellows body, 21b bellows mounting flange, 22 insulator flange, 22a insulator, 22b filler metal, 31A third flange, 31B fourth flange, 100, 200, 300, 400, 500, 600, 700 vacuum circuit breaker.

Claims

1. A vacuum circuit breaker comprising a vacuum valve with a bellows for maintaining a vacuum, a tank for housing the vacuum valve, a flange attached to the opening of the tank to form a space for sealing high-pressure insulating gas, and an operating mechanism installed outside the tank for opening and closing the vacuum valve, wherein the flanges consist of a first flange on the atmospheric side outside the tank and a second flange on the insulating gas side inside the tank, and an intermediate chamber is formed between the first flange and the second flange, and the vacuum valve is fixed to the second flange via an insulating tube, and the intermediate chamber, the interior of the insulating tube, and the interior of the bellows of the vacuum valve are connected, maintaining a pressure intermediate between the gas pressure of the insulating gas and atmospheric pressure.

2. A vacuum circuit breaker according to claim 1, wherein a gas pipe for supplying gas to said intermediate chamber is provided outside said tank.

3. A vacuum circuit breaker according to claim 1 or claim 2, wherein the operating mechanism and the flange are provided below the tank.

4. A vacuum circuit breaker according to any one of claims 1 to 3, wherein the contact area between the operating mechanism and the opening for the operating mechanism provided in the first flange is kept airtight by a sliding seal.

5. A vacuum circuit breaker as claimed in any one of claims 1 to 3, wherein the contact area between the operating mechanism and the opening for the operating mechanism provided in the first flange is kept airtight by a bellows.

6. A vacuum circuit breaker according to any one of claims 1 to 5, wherein the second flange and the insulating cylinder are integrally formed.

7. A vacuum circuit breaker according to any one of claims 1 to 6, wherein the intermediate chamber is provided inside the tank.

8. A vacuum circuit breaker according to any one of claims 1 to 6, wherein the intermediate chamber is provided on the outside of the tank.

9. A vacuum circuit breaker according to any one of claims 1 to 8, which is for single-phase use and includes one vacuum valve.

10. A vacuum circuit breaker according to any one of claims 1 to 8, which is a three-phase circuit breaker having three vacuum valves.

11. A vacuum circuit breaker as claimed in claim 10, wherein a three-phase branching section for branching the operating mechanism into three phases is provided in the intermediate chamber.

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