Vacuum circuit breaker and method for manufacturing a vacuum circuit breaker

Abstract

The vacuum valve (5) is provided with a fixed side contact (5a) and a movable side contact (5b) inside. The movable side contact (5b) is connected to the movable electrode shaft (5c). The movable electrode shaft (5c) is connected to the bellows (5d) and supported by a bearing (5h). The bearing (5h) is fixed to the bearing mounting part (5g) by bolts. A fixed airtight part (5j) is provided. The fixed airtight part (5j) is used to provide an airtight seal on the surface of the bearing (5h) fixed to the bearing mounting part (5g). The bearing (5h) is provided with an airtight sliding part (5k). The airtight sliding part (5k) is used to provide an airtight seal on the sliding surface between the bearing (5h) and the movable electrode shaft (5c).

Description

Technical Field

[0001] This disclosure relates to vacuum circuit breakers and methods for manufacturing vacuum circuit breakers. Background Technology

[0002] Gas-insulated switchgear consists of a main circuit section with applied high voltage, an operating mechanism section for driving the main circuit section, and a control circuit section. The main circuit section of the gas-insulated switchgear is housed within a pressurized, sealed container containing a gas with high insulating properties. Increasing the pressure of the insulating gas enhances the insulation performance, enabling miniaturization of the entire switchgear. SF6 gas, known for its high insulating properties, is commonly used as the insulating gas. However, SF6 has a high global warming coefficient. Therefore, in recent years, gas-insulated switchgear using pressurized, sealed dry air with no environmental impact has also been commercialized.

[0003] In addition, circuit breakers, which serve as switches in the main circuit and have the function of interrupting large currents, include gas circuit breakers that use gases with excellent arc-extinguishing properties, such as SF6 gas, and vacuum circuit breakers that use vacuum valves in the arc-extinguishing chamber. The application of vacuum circuit breakers began at lower voltage levels, but in recent years, with increasing environmental awareness, the demand for vacuum circuit breakers, which have no impact on the environment, has been continuously increasing compared to gas circuit breakers using SF6 gas, which has a higher global warming coefficient. Furthermore, vacuum circuit breakers are gradually being applied to higher voltage levels.

[0004] Thus, gas-insulated switchgear equipped with vacuum circuit breakers has begun to be used at higher voltage levels. The vacuum valve, serving as the arc-extinguishing chamber of the vacuum circuit breaker, is a structure formed by brazing and sealing metals such as stainless steel or copper with insulators such as ceramics, maintaining a high vacuum state inside the container. The vacuum valve's interior contains contact sections for opening and closing high voltage and high current; one contact is fixed to the vacuum valve's container, while the other contact is designed to be movable for opening and closing.

[0005] The movable part of a vacuum valve uses a metal bellows, a flexible, corrugated cylindrical structure that allows for opening and closing of the contacts while maintaining a high vacuum within the valve. However, the bellows is constantly subjected to stress due to the pressure difference between the surrounding pressure and the internal vacuum. For example, when the vacuum valve is used at atmospheric pressure, the pressure difference of one atmosphere continuously acts on the bellows. Furthermore, the bellows expands and contracts during the opening and closing of the valve contacts, generating additional stress due to this expansion and contraction. Therefore, the bellows is a mechanical weakness of the vacuum valve.

[0006] Furthermore, in gas-insulated switchgear, increasing the gas pressure inside the switchgear container improves insulation performance and enables miniaturization of the device. Therefore, the pressure inside the container of high-voltage gas-insulated switchgear increases. When a vacuum valve is applied to a high-voltage gas-insulated switchgear, stress arises on the bellows due to the pressure difference between the high pressure inside the switchgear container and the vacuum inside the valve. Consequently, compared to when the vacuum valve is used at atmospheric pressure, the stress acting on the bellows due to the pressure difference is greater, leading to a shorter bellows lifespan relative to the number of opening and closing cycles, which becomes a technical problem.

[0007] In patent document 1 Figure 4 In the structure shown, by forming an intermediate chamber sealed by an insulating cylinder on the movable side of the vacuum valve, and setting the pressure of the intermediate chamber to the intermediate pressure between atmospheric pressure and vacuum, the pressure difference and stress acting on the bellows of the vacuum valve are reduced. Furthermore, in Patent Document 1 Figure 1 In this structure, the intermediate chamber uses two bellows, a first bellows and a second bellows, and the pressure inside the intermediate chamber is set to an intermediate pressure between high pressure and vacuum. In this case, stress is generated on the second bellows due to the pressure difference between the high pressure and the intermediate pressure, and stress is generated on the other first bellows due to the pressure difference between the high pressure and the intermediate pressure. Existing technical documents Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2004-236455 Summary of the Invention The technical problem that the invention aims to solve

[0009] The aforementioned patent document 1 Figure 4 In this structure, the movable rod in the intermediate chamber is also subjected to high voltage, and the pressure inside the intermediate chamber is a lower pressure between atmospheric pressure and vacuum. Therefore, the insulation performance of the gas is reduced. Consequently, to withstand the high voltage insulation, the insulation distance needs to be increased, making it difficult to achieve product miniaturization.

[0010] Furthermore, the aforementioned patent document 1 Figure 1 In this structure, due to the use of two bellows, the vacuum valve itself becomes larger, and it is similar to the structure described in Patent Document 1 above. Figure 4 Compared to other structures, the stress acting on the bellows due to pressure difference is also greater, which poses a technical problem of shortening the mechanical life of the bellows.

[0011] This disclosure discloses a technology for solving the above-mentioned technical problems, with the aim of providing a vacuum circuit breaker in which the parts other than the vacuum valve can be insulated by a high-pressure insulating gas, and the gas-insulated switchgear can be miniaturized as a whole. Technical solutions adopted to solve technical problems

[0012] The vacuum circuit breaker disclosed herein has a vacuum valve installed inside a sealed container, and the space inside the sealed container is filled with a high-pressure insulating gas. The vacuum valve has a fixed side contact and a movable side contact inside, and the movable side contact is connected to the movable electrode shaft. The movable electrode shaft is connected to the bellows and supported by a bearing, which is fixed to the bearing mounting part by bolts. An airtight fixing part is provided, which is used to provide an airtight seal to the surface where the bearing is fixed to the bearing mounting part. The bearing is provided with an airtight sliding part, which is used to provide an airtight seal for the sliding surface between the bearing and the movable electrode shaft. Furthermore, the manufacturing method of the vacuum circuit breaker disclosed herein comprises the following steps: a step of preparing a bearing, wherein a first sealing member is installed in the groove of the fixed airtight portion of the bearing, and a second sealing member is installed in the groove of the airtight sliding portion; and In the air, with the fixed side contact and the movable side contact in contact, the bearing is installed on the movable electrode shaft and fixed by bearing fixing bolts, thereby sealing the air in the inner circumferential space of the bellows. Invention Effects

[0013] According to the vacuum circuit breaker and its manufacturing method disclosed herein, the parts other than the vacuum valve can be insulated by a high-pressure insulating gas, and the overall gas-insulated switchgear can be miniaturized. Attached Figure Description

[0014] Figure 1 This is a side sectional view showing the gas-insulated switchgear of Embodiment 1. Figure 2 This is a schematic diagram showing the vacuum circuit breaker section of a gas-insulated switchgear as a comparative example. Figure 3 This is a schematic diagram showing the vacuum circuit breaker section of the gas-insulated switchgear according to Embodiment 1. Figure 4 This is an enlarged view showing the bearing periphery of the movable electrode shaft of the vacuum valve in Embodiment 1. Figure 5This is a schematic diagram showing the vacuum circuit breaker section of the gas-insulated switchgear according to Embodiment 1. Figure 6 This is an enlarged view showing the bearing periphery of the movable electrode shaft of the vacuum valve in Embodiment 2. Figure 7 This is an enlarged view showing the bearing periphery of the movable electrode shaft of the vacuum valve in Embodiment 3. Detailed Implementation

[0015] Implementation method 1. This embodiment relates to vacuum circuit breakers, and more particularly to the vacuum valve structure of vacuum circuit breakers. The contents described in this embodiment can be used in vacuum circuit breakers of gas-insulated switchgear. Figure 1 This is a side sectional view showing a gas-insulated switchgear with a vacuum circuit breaker. The gas-insulated switchgear 1 has a sealed container 8 containing a vacuum circuit breaker 2, a disconnecting switch and a grounding switch 6, a busbar 7, power cables 9, etc., and the sealed container 8 is filled with an insulating gas such as dry air. The vacuum circuit breaker 2 consists of an operating mechanism 3 of the vacuum circuit breaker disposed outside the sealed container 8 and a main circuit section 4 of the vacuum circuit breaker disposed inside the sealed container 8. A vacuum valve 5 is provided in the main circuit section 4 of the vacuum circuit breaker. Figure 2 This is a schematic diagram showing the vacuum circuit breaker section of a gas-insulated switchgear relative to a comparative example of this embodiment. The space 8a inside the sealed container 8 is filled with high-pressure insulating gas. The vacuum valve 5 has a fixed-side contact 5a and a movable-side contact 5b inside, and the movable-side contact 5b is connected to the movable electrode shaft 5c.

[0016] The movable electrode shaft 5c is connected to the bellows 5d, maintaining a vacuum inside the vacuum valve 5. The other end of the bellows 5d is mounted to the container 5w that constitutes the vacuum valve 5. Furthermore, the movable electrode shaft 5c passes through the inner circumferential space 5f of the bellows 5d and extends to the outside of the vacuum valve 5. The movable electrode shaft 5c is supported by a bearing 5e, which is fixed to the bearing mounting portion 5g by bolts. The bearing 5e is made of thermoplastic resin or thermosetting resin. The reason is that a large current flows through the vacuum circuit breaker via the fixed side contact 5a, the movable side contact 5b, and the movable electrode shaft 5c. However, if the bearing 5e of the movable electrode shaft is made of metal, a current path will be formed passing through the fixed side contact 5a, the movable side contact 5b, the movable electrode shaft 5c, the bellows 5d, the bearing mounting part 5g, the bearing 5e of the movable electrode shaft, and the movable electrode shaft 5c. Current will also flow through this current path, and the current flowing through the bellows 5d will damage it. Therefore, by making the bearing 5e into a thermoplastic resin or a thermosetting resin, current can be prevented from flowing through the bellows 5d.

[0017] The movable electrode shaft 5c extending outside the vacuum valve 5 is connected to the insulating operating rod 10, which in turn is connected to the operating shaft 12 of the vacuum circuit breaker. The operating shaft 12 of the vacuum circuit breaker passes through the airtight sliding part 11 and extends outside the sealed container 8, connecting with... Figure 2 Operating mechanism 3 of the vacuum circuit breaker (not shown in the figure) Figure 1 (Connection). Furthermore, the bearing 5e of the movable electrode shaft only mechanically supports the movable electrode shaft 5c and is not hermetically sealed. Therefore, a portion of the inner circumferential space 5f of the bellows 5d contains the same high-pressure insulating gas as the space 8a within the sealed container 8.

[0018] Figure 3 This is a schematic diagram showing the vacuum circuit breaker section of the gas-insulated switchgear according to Embodiment 1. Figure 2 and Figure 3 The difference is that, Figure 2 The bearing 5e portion of the movable electrode shaft shown is in Figure 3 The bearing 5h of the movable electrode shaft of the vacuum valve, which has been changed to Embodiment 1, is as follows: Regarding other parts... Figure 3 and Figure 2 Same. Also... Figure 3 The diagram shows the open state of the circuit breaker contacts. Furthermore, in order to address... Figure 2 For the same reason explained by the bearing 5e shown, the bearing 5h of the movable electrode shaft is made of thermoplastic resin or thermosetting resin.

[0019] Figure 4 It is shown Figure 3 An enlarged view of the bearing 5h surrounding the movable electrode shaft of the vacuum valve. In the bearing 5h of the movable electrode shaft of the vacuum valve in Embodiment 1, a groove for a fixing airtight portion 5j is provided. This fixing airtight portion 5j is used to provide an airtight seal to the surface where the bearing 5h is fixed to the bearing mounting portion 5g. It is configured to allow the installation of sealing components such as O-rings and gaskets to achieve an airtight seal. Furthermore, the bearing 5h of the movable electrode shaft has a groove for an airtight sliding portion 5k. This airtight sliding portion 5k is used to provide an airtight seal to the sliding surface between the bearing 5h and the movable electrode shaft 5c. It is equipped with sealing components such as T-rings, X-rings, or a combination of resin and spring. Thus, it is configured to allow for airtight sliding when the movable electrode shaft 5c is in motion. A T-ring is a component with a T-shaped cross-section. Figure 4 The image shows the use of a T-ring. An X-ring refers to an annular sealing gasket with an X-shaped cross-section that is nearly polygonal. As a sealing component composed of resin and a spring, it is envisioned to be Balseal (registered trademark) manufactured by BalSeal Engineering Co., Ltd. In addition, for vacuum valves used in vacuum circuit breakers, it is generally impossible to maintain a high vacuum state inside the vacuum valve without using a bellows. To drive the movable electrode shaft 5c while maintaining a high vacuum, a bellows 5d is necessary. An airtight sliding part 5k can be achieved using a rubber T-ring, but this is only for gas sealing. While rubber T-rings and the like can achieve gas sealing and maintain a low vacuum for a short time, they cannot maintain a high vacuum.

[0020] Figure 5 This is a schematic diagram showing the vacuum circuit breaker section of the gas-insulated switchgear according to Embodiment 1. Figure 3 The diagram shows the open state of the circuit breaker contacts, while... Figure 5 The diagram shows the closed state of the circuit breaker contacts. Figure 3 and Figure 5 The difference is that, Figure 3 The middle contact is disconnected; in contrast, in Figure 5 The movable side contact 5b moves towards the fixed side contact 5a to close the contact, and the movable electrode shaft 5c, the insulating operating rod 10, and the operating shaft 12 of the vacuum circuit breaker, which are connected to the movable side contact 5b, also move towards the fixed side contact 5a. Furthermore, with the movement of the movable electrode shaft 5c, the bellows 5d elongates, and the inner circumferential space 5f of the bellows increases.

[0021] When manufacturing vacuum valves, such as Figure 5 As shown, the contacts of vacuum valve 5 are in the closed state. This is because the internal space 5m of the vacuum valve is a vacuum, while the inner circumferential space 5f of the bellows is at atmospheric pressure, and the movable contact 5b is pressed due to the pressure difference. Next, the method for sealing the inner circumferential space 5f of the bellows by mounting the bearing 5h of the movable electrode shaft on the vacuum valve 5 will be described. When sealing ordinary air within the inner circumferential space 5f of the bellows, the bearing 5h is prepared in advance as follows: O-rings, gaskets, or other sealing components (first sealing components) are installed in the groove of the airtight portion 5j for fixing the bearing 5h of the movable electrode shaft, and further, T-rings, X-rings, or sealing components composed of resin and springs (second sealing components) are installed in the groove of the airtight sliding portion 5k. Then, in air, with the vacuum valve contacts closed, the bearing 5h of the movable electrode shaft is installed and secured with bearing fixing bolts 5i.

[0022] When dry air or inert gas is sealed in the inner circumferential space 5f of the bellows, a vacuum valve and a bearing 5h for the movable electrode shaft are prepared in the sealed space for assembly work. After the sealed space for assembly work is filled with dry air or inert gas, the bearing 5h is installed in the sealed space for assembly work and fixed with the bearing fixing bolt 5i to complete the operation. That is, in this case, a bearing 5h is prepared with a first sealing member installed in the groove of the fixed airtight part 5j and a second sealing member installed in the groove of the airtight sliding part 5k. In the closed space for assembly operation filled with dry air or inert gas, with the fixed side contact 5a in contact with the movable side contact 5b, the bearing 5h is installed on the movable electrode shaft 5c and the bearing 5h is fixed by the bearing fixing bolt 5i, thereby sealing the dry air or inert gas in the inner circumferential space 5f of the bellows 5d. In addition, during the manufacture of vacuum valve 5, there is no insulating gas in the sealed container 8. After manufacturing vacuum valve 5, vacuum valve 5 and other components are assembled into sealed container 8, the lid of sealed container 8 is closed, and finally insulating gas is sealed into the space 8a inside sealed container 8.

[0023] Through the above manufacturing process, Figures 3-5 In the case of the vacuum circuit breaker structure shown in Embodiment 1, when the contacts of the vacuum valve 5 are closed, the inner circumferential space 5f of the bellows is at atmospheric pressure. When the contacts of the vacuum valve 5 are closed ( Figure 5Let the volume of the inner circumferential space 5f of the bellows be V, and the pressure be P. Let the volume of the inner circumferential space 5f of the bellows when the contacts of the vacuum valve 5 are open be V1. Then, the pressure in the inner circumferential space 5f of the bellows when the contacts of the vacuum valve 5 are open is V / V1×P. Since V1 < V, the pressure in the inner circumferential space 5f of the bellows will increase slightly to above atmospheric pressure accordingly. However, the inner circumferential space 5f of the bellows will not be subjected to the high pressure of the insulating gas in the space 8a of the sealed container 8. Therefore, the stress acting on the bellows 5d due to the pressure difference can be reduced.

[0024] In addition, by setting the volume of the inner circumferential space 5f of the bellows to be larger and the difference between the volumes V and V1 to be smaller, the pressure fluctuation of the inner circumferential space 5f of the bellows can be reduced, and the mechanical life of the bellows 5d can be extended. On the other hand, the space 8a inside the sealed container 8 is filled with high-pressure insulating gas. Therefore, the parts other than the vacuum valve can be insulated by high-pressure insulating gas at the periphery of the insulating operating rod 10, thereby enabling the overall miniaturization of the device.

[0025] By adopting the above structure, the size of the vacuum valve 5 can be controlled to be the same as that of existing products. The pressure on the inner circumference of the bellows is in the range of atmospheric pressure to slightly above atmospheric pressure, and the bellows 5d only bears the stress caused by the pressure difference between this pressure and the vacuum. Even if the vacuum valve 5 is placed in a gas-insulated switch device 1 that is insulated by a high-pressure insulating gas, the pressure on the inner circumference of the vacuum valve 5 is still in the range of atmospheric pressure to slightly above atmospheric pressure, and is not affected by the higher pressure caused by the insulating gas around the vacuum valve 5. In addition, the movable electrode shaft 5c and part of the insulating operating rod 10 of the vacuum valve 5 are insulated by an insulating gas with a high pressure, thus enabling the miniaturization of the gas-insulated switch device 1. Furthermore, the gas compartment on the inner circumference of the bellows is a space enclosed by the metal bellows 5d and the bearing 5h of the movable electrode shaft. Almost no electric field is generated inside this space; therefore, the insulation performance within the gas compartment on the inner circumference of the bellows does not need to be considered. That is, an electric field is generated by a potential difference (voltage difference), but there is no potential difference within the metal bellows 5d, therefore, no electric field is generated. Moreover, sealing the dry air prevents condensation. In addition, sealing with inert gas removes oxygen and prevents deterioration due to oxidation.

[0026] Implementation method 2. Figure 6 This is an enlarged view showing the bearing periphery of the movable electrode shaft of the vacuum valve in Embodiment 2. Compared with Embodiment 1... Figure 4 The difference is that, Figure 6The bearing is equipped with a 5p gas supply port. Other points are... Figure 4 The situation is the same. In Embodiment 1, atmospheric air, dry air, or an inert gas is sealed into the inner circumferential space 5f of the bellows while the vacuum valve contacts are closed. In Embodiment 2, a gas supply port 5p is provided on the bearing 5n. After the bearing 5n is installed on the movable electrode shaft 5c, the air in the inner circumferential space 5f of the bellows is evacuated through the gas supply port 5p, and any gas, such as an inert gas (helium, neon, argon, or other rare gases, or nitrogen), is sealed into the bellows at any pressure through the gas supply port 5p.

[0027] Since the gas supply port 5p is only used during gas sealing, the hole of the gas supply port 5p is sealed after gas sealing. As a specific example, when sealing any gas at atmospheric pressure into the inner circumferential space 5f of the bellows, the gas supply port 5p is pre-designed as a threaded hole, and piping is installed on this threaded hole. The air in the inner circumferential space 5f of the bellows is evacuated, and any gas is then sealed in at atmospheric pressure. Afterwards, even if the piping is removed, the inner circumferential space 5f of the bellows and its surrounding area remain at atmospheric pressure, therefore, gas leakage is almost nonexistent. Then, the threaded hole serving as the gas supply port 5p is sealed with a sealing bolt or a bolt with a gas-sealing material such as an O-ring, thus making the inner circumferential space 5f of the bellows a closed space.

[0028] Furthermore, when any gas above atmospheric pressure is sealed into the inner circumferential space 5f of the bellows, the gas supply port 5p can be designed as a piping shape instead of a hole shape (threaded hole). That is, piping can be installed by welding or other methods. Moreover, this piping section allows for evacuation and gas sealing of the inner circumferential space 5f of the bellows. After the gas is sealed, the inner circumferential space 5f of the bellows can be made a sealed space by sealing the root of the piping installed at the gas supply port 5p. In other words, the piping can be cut airtightly by flattening the end of the piping. Therefore, the inner circumferential space 5f of the bellows is in a state where there is almost no oxygen, thus preventing the oxidation of the bellows 5d and the movable electrode shaft 5c, and maintaining its long-term integrity.

[0029] Implementation method 3. Figure 7 This is an enlarged view showing the bearing periphery of the movable electrode shaft of the vacuum valve in Embodiment 3. Compared with Embodiment 1... Figure 4 The difference is that, Figure 7 An insulating sheet 5r is sandwiched between the bearing mounting part 5g and the bearing 5q. Here, the insulating sheet is made of rubber, nylon, PTFE (polytetrafluoroethylene), etc. Furthermore, in implementation method 1 Figure 4 In this embodiment, the bearing 5h is made of resin, and the bearing fixing bolt 5i is made of metal. In contrast, in embodiment 3... Figure 7 In this design, bearing 5q is made of metal, while bearing fixing bolt 5s is made of insulating material. Non-magnetic metals such as aluminum, copper, brass, and stainless steel are used as the metal. Furthermore, thermoplastic resins such as PET (polyethylene terephthalate) and PBT (polybutylene terephthalate), or thermosetting resins such as epoxy resin, are used as the insulating material. Other points are... Figure 4 The situation is the same.

[0030] By making the bearing 5q a machined metal component, its dimensional accuracy is higher compared to resin products, thereby improving its performance or airtightness as a mechanical bearing. Furthermore, even though the bearing 5q is made of metal, because it is fitted with an insulating sheet 5r and the bearing fixing bolts 5s are made of insulating material, there is no path for current to flow through the bellows 5d, thus preventing the bellows 5d from being affected by current flow.

[0031] Furthermore, in embodiments 1 to 3, the use of dry air as an insulating gas was described, but SF6 gas or the like can also be used as other insulating gases.

[0032] This application describes various exemplary implementation methods and embodiments, but the various features, methods and functions described in one or more implementation methods are not limited to specific implementation methods, and can be applied to implementation methods alone or in various combinations. Therefore, within the scope of the technology disclosed in this application, numerous variations not illustrated can be contemplated. For example, these include variations, additions, or omissions of at least one constituent element, as well as the extraction of at least one constituent element and its combination with constituent elements of other embodiments. Symbol Explanation

[0033] 1 Gas-insulated switchgear; 2 Vacuum circuit breaker; 4 Main circuit section; 5 Vacuum valve; 5a Fixed side contact; 5b Movable side contact; 5c Movable electrode shaft; 5d Bellows; 5f Inner peripheral space; 5g Bearing mounting section; 5h Bearing; 5j Fixed airtight section; 5k Airtight sliding section; 5n Bearing; 5p Gas supply port; 5q Bearing; 5r Insulating sheet; 8 Sealed container.

Claims

1. A vacuum circuit breaker, wherein a vacuum valve is installed inside a sealed container, and a high-pressure insulating gas is sealed within the space of the sealed container, characterized in that, The vacuum valve has a fixed side contact and a movable side contact inside, and the movable side contact is connected to the movable electrode shaft. The movable electrode shaft is connected to the bellows and supported by a bearing, which is fixed to the bearing mounting part by bolts. A fixing airtight part is provided, which is used to provide an airtight seal to the surface where the bearing is fixed to the bearing mounting part, and... The bearing is provided with an airtight sliding part, which is used to provide an airtight seal for the sliding surface between the bearing and the movable electrode shaft.

2. The vacuum circuit breaker according to claim 1, characterized in that, When the contacts of the vacuum valve are closed, the pressure in the inner circumferential space of the bellows becomes atmospheric pressure. When the contacts of the vacuum valve are open, the volume of the inner circumferential space of the bellows decreases, and the pressure in the inner circumferential space of the bellows increases accordingly to be greater than atmospheric pressure.

3. The vacuum circuit breaker according to claim 2, characterized in that, The inner circumferential space of the bellows is sealed with air, dry air, or an inert gas.

4. The vacuum circuit breaker according to any one of claims 1 to 3, characterized in that, The bearing is made of thermoplastic resin or thermosetting resin.

5. The vacuum circuit breaker according to any one of claims 1 to 3, characterized in that, The bearing is made of metal, and an insulating sheet is sandwiched between the bearing mounting portion and the bearing.

6. A method for manufacturing a vacuum circuit breaker, which is the method for manufacturing a vacuum circuit breaker according to claim 1 or 2, characterized in that, It consists of the following processes: The process of preparing a bearing, wherein a first sealing component is installed in the groove of the fixed airtight part of the bearing, and a second sealing component is installed in the groove of the airtight sliding part; as well as In the air, with the fixed side contact in contact with the movable side contact, the bearing is installed on the movable electrode shaft and the bearing is fixed by bearing fixing bolts, thereby sealing the air in the inner circumferential space of the bellows.

7. A method for manufacturing a vacuum circuit breaker, which is the method for manufacturing a vacuum circuit breaker according to claim 3, characterized in that, It consists of the following processes: The process of preparing the bearing, wherein a first sealing member is installed in the groove of the fixed airtight part of the bearing, and a second sealing member is installed in the groove of the airtight sliding part; and In a closed space for assembly operations filled with dry air or inert gas, with the fixed side contact in contact with the movable side contact, the bearing is installed on the movable electrode shaft and the bearing is fixed by bearing fixing bolts, thereby sealing the dry air or inert gas in the inner circumferential space of the bellows.

8. A method for manufacturing a vacuum circuit breaker, as described in claim 1, characterized in that, A gas supply port is provided in the bearing. After the bearing is installed on the movable electrode shaft, the air in the inner circumferential space of the bellows is evacuated through the gas supply port, and gas is sealed into the inner circumferential space through the gas supply port.

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