Gas-insulated switchgear

Abstract

The vacuum circuit breaker (3) of the gas-insulated switchgear (1) comprises a vacuum valve (10), a fixed contact (10b) fixed inside the vacuum valve (10), a movable contact (10a) arranged opposite the fixed contact (10b), and a bellows (11) that moves in conjunction with the movement of the movable contact (10a). The vacuum valve (10) has a vacuum compartment (22) in which the fixed contact (10b) and the movable contact (10a) are arranged, and a gas compartment (19) that includes the bellows (11). The vacuum valve (10) is provided with a piston device (160) connected to the gas compartment (19) and having a preset volume difference that corresponds to the volume difference caused by the expansion and contraction of the bellows (11) between the closed and open states of the vacuum valve (10).

Description

[Technical Field]

[0001] The present disclosure relates to gas-insulated switchgear. [Background technology]

[0002] Conventional gas-insulated switchgear consists of a main circuit section to which high voltage is applied, an operating mechanism section that drives the switches in the main circuit section, and a control circuit section. The main circuit section is placed in a container where a gas with high insulating properties is pressurized and sealed, and by increasing the pressure of the insulating gas, the insulation performance is improved and the overall size of the device is made smaller. SF6 gas, which has high insulating properties, is generally used as the insulating gas, but because SF6 gas has a high global warming potential, gas-insulated switchgear that uses pressurized and sealed dry air, which has no environmental impact, has also been commercialized in recent years.

[0003] Furthermore, among the main circuit switches, circuit breakers with the function of interrupting large currents include gas circuit breakers that use SF6 gas, which has excellent arc extinguishing performance, and vacuum circuit breakers that use a vacuum valve in the arc extinguishing chamber. Vacuum circuit breakers were first used in the low voltage class, but with the rise in environmental awareness in recent years, there has been an increasing demand for vacuum circuit breakers, which have a lower environmental impact than gas circuit breakers that use SF6 gas, which has a high global warming potential. As a result, the range of application of vacuum circuit breakers has gradually expanded, and they are now being used in transmission voltage classes of 72kV and above.

[0004] As mentioned above, gas-insulated switchgear equipped with vacuum circuit breakers is beginning to be applied to high-voltage applications. The vacuum valve, which serves as the arc extinguishing chamber of the vacuum circuit breaker, is constructed by brazing metals such as stainless steel or copper to insulating materials such as ceramic, and is sealed, with the interior maintained in a high vacuum. Inside the vacuum valve are contacts that open and close high voltages and large currents, one contact is fixed to the vacuum valve housing, and the other contact is movable for opening and closing.

[0005] The moving parts of a vacuum valve use metal bellows, which are cylindrical and flexible. This allows the contacts to open and close while maintaining the high vacuum inside the valve. However, the bellows of a vacuum valve is constantly subjected to stress due to the pressure difference between the surrounding pressure and the internal vacuum. For example, when a vacuum valve is used under atmospheric pressure, the pressure difference between atmospheric pressure and the vacuum (1 atmosphere) is constantly applied to the bellows. Furthermore, the bellows expands and contracts when the contacts are opened and closed, which also causes stress.

[0006] For this reason, the bellows is one of the mechanical weak points of the vacuum valve. Furthermore, in gas-insulated switchgear, increasing the gas pressure inside the vessel improves insulation performance, allowing for the device to be made more compact. Therefore, in high-voltage gas-insulated switchgear, the pressure inside the vessel increases. When a vacuum valve is used in such a device, the pressure difference between the high-pressure gas inside the vessel and the vacuum inside the vacuum valve increases the stress on the bellows. As a result, the lifespan of the bellows is shortened, and the number of times it can be opened and closed is limited.

[0007] In contrast to this, in conventional gas-insulated switchgear, the part of the vacuum valve containing the bellows is treated as a small gas compartment separate from the device's container, and the pressure is set lower than that inside the container, thereby reducing the stress on the bellows (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-060244 Summary of the Invention [Problem to be solved by the invention]

[0009] The bellows of the vacuum valve of a conventional gas-insulated switchgear expands when the contact is closed and contracts when the contact is opened. As a result, the volume of the gas compartment containing the bellows changes when the vacuum valve is opened or closed, causing the pressure inside the gas compartment to increase or decrease. This pressure fluctuation in the gas compartment causes a decrease in pressure, which can lead to a decrease in insulation performance. Furthermore, an increase in pressure can increase the stress on the bellows. Furthermore, the pressure fluctuation in the gas compartment can increase the load on the vacuum circuit breaker.

[0010] The present disclosure discloses a technique for solving the above-described problems, and aims to provide a gas-insulated switchgear that prevents a deterioration in insulation performance and reduces the load on a vacuum circuit breaker. [Means for solving the problem]

[0011] The gas insulated switchgear of the present disclosure comprises: In a gas-insulated switchgear equipped with a vacuum circuit breaker, The vacuum circuit breaker comprises: Multiple Vacuum valve and Each of the vacuum valves has: a fixed contact fixed inside the vacuum valve; a movable contact arranged opposite the fixed contact; a bellows that moves in conjunction with the movement of the movable contact; Each of the vacuum valves has a vacuum compartment in which the fixed contact and the movable contact are disposed, and a gas compartment containing the bellows, All The bellows are connected to the gas compartment, and expand and contract between the closing and opening states of each vacuum valve. All with a volumetric difference and a preset volumetric difference One It is equipped with a piston device. [Effects of the Invention]

[0012] According to the gas insulated switchgear of the present disclosure, It is possible to obtain a gas-insulated switchgear that prevents a decrease in insulation performance and reduces the load on the vacuum circuit breaker. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a schematic front view showing the configuration of a gas-insulated switchgear according to a first embodiment. [Figure 2] 2 is a schematic diagram showing an open state of a vacuum circuit breaker of the gas-insulated switchgear shown in FIG. 1. FIG. [Figure 3] 2 is a schematic diagram showing a closed state of a vacuum circuit breaker of the gas-insulated switchgear shown in FIG. 1. FIG. [Figure 4] FIG. 4 is a diagram for explaining the sizes of various parts of the vacuum circuit breaker shown in FIGS. 2 and 3. [Figure 5] FIG. 4 is a diagram for explaining the sizes of various parts of the vacuum circuit breaker shown in FIGS. 2 and 3. [Figure 6] 10 is a schematic plan view of the configuration of a vacuum circuit breaker of a gas-insulated switchgear according to a second embodiment, as viewed from above. FIG. [Figure 7] 7 is a diagram showing the configuration of a piston device of the vacuum circuit breaker shown in FIG. 6. FIG. [Figure 8] FIG. 10 is a diagram showing the configuration of a piston device of a vacuum circuit breaker of a gas-insulated switchgear according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] Embodiment 1 Fig. 1 is a front schematic view showing the configuration of a gas-insulated switchgear according to embodiment 1. Fig. 2 is a schematic view showing an open state of a vacuum circuit breaker of the gas-insulated switchgear shown in Fig. 1. Fig. 3 is a schematic view showing a closed state of the vacuum circuit breaker of the gas-insulated switchgear shown in Fig. 1. Fig. 4 is a diagram for explaining the sizes of various parts of the vacuum circuit breaker shown in Figs. 2 and 3. Fig. 5 is a diagram for explaining the sizes of various parts of the vacuum circuit breaker shown in Figs. 2 and 3.

[0015] As shown in Fig. 1, the gas-insulated switchgear 1 is configured by combining disconnector-use sealed containers 2a, 2b, and 2c with a circuit breaker-use sealed container 3. Each of the disconnector-use sealed containers 2a, 2b, and 2c is equipped with a disconnector-use earthing switch 4a, 4b, and 4c as a main circuit unit. The circuit breaker-use sealed container 3 is equipped with a vacuum circuit breaker 5 as a main circuit unit. A busbar 8 is connected to each of the disconnector-use earthing switches 4a, 4b, and 4c and the circuit breaker-use sealed container 3. Note that, although the busbar 8 is shown as a single wire in Fig. 1 for convenience, it is actually configured with a three-phase wire.

[0016] Inside each of the sealed containers 2a, 2b, 2c, 3, insulating gas such as SF6 gas or dry air, which has high insulating properties, is pressurized and sealed, thereby insulating the disconnector earthing switches 4a, 4b, 4c and vacuum circuit breakers 5 inside each of the sealed containers 2a, 2b, 2c, 3. In addition, bushings 6a, 6b, 6c are provided at the connection between the disconnector earthing switches 4a, 4b, 4c inside each of the disconnector sealed containers 2a, 2b, 2c and the outside of each of the sealed containers 2a, 2b, 2c.

[0017] Bushings 6a, 6b, and 6c are made of insulating resin with a metal conductor positioned in the center. They hermetically seal the gas inside each sealed container 2a, 2b, and 2c, maintaining insulation between the grounded metal sealed containers 2a, 2b, and 2c and the busbars 8 of the high-voltage main circuit disconnector and earthing switches 4a, 4b, and 4c. The bushings 6a, 6b, and 6c are then connected to cables 7a, 7b, and 7c. In the configuration shown in Figure 1, power received via cable 7a is output via disconnector and earthing switch 4a and vacuum circuit breaker 5 to cables 7b and 7c via the disconnector and earthing switches 4b and 4c of the sealed containers 2b and 2c, which serve as feeder panels. The operating unit 9 of the vacuum circuit breaker 5 is located outside the sealed containers.

[0018] As shown in Figures 2 and 3, the interior of the circuit breaker sealed vessel 3 is a gas compartment 18 in which three phases of vacuum interrupters 10 are arranged. Each vacuum interrupter 10 has a movable contact 10a, a fixed contact 10b, and a bellows 11. The fixed contact 10b is fixed inside the vacuum interrupter 10. The movable contact 10a is arranged opposite the fixed contact 10b. The vacuum interrupter 10 has a vacuum compartment 22 in which the fixed contact 10b and the movable contact 10a are arranged, and a gas compartment 19 in which the bellows 11 is arranged.

[0019] The bellows 11 moves the movable contact 10a while maintaining a vacuum in the vacuum compartment 22 of the vacuum interrupter 10. The movable contact 10a of the vacuum interrupter 10 is connected to the movable part 12 of the vacuum circuit breaker 5. The movable part 12 of the vacuum interrupter 5 is surrounded by the vacuum interrupter 10 and the insulating cylinder 13, and is hermetically sealed by the insulating cylinder 13, the flange 17, and the piston container 16a. This forms a gas compartment 19 containing the bellows 11 of the vacuum interrupter 10.

[0020] 2, the gas compartment 19 containing the bellows 11 of the three-phase vacuum valve 10 is connected at the flange 17. It is also connected to the interior of the piston container 16a, forming the gas compartment 19 containing the bellows 11 of the vacuum valve 10. The piston device 160 connected to the gas compartment 19 in this way has a preset volume difference that corresponds to the expansion and contraction of the bellows 11 between the closed and open states of the vacuum valve 10. This point will be explained in detail later.

[0021] The movable part 12 of the vacuum interrupter 10 is connected to a three-phase shaft 15 via a contact pressure spring 14 outside the sealed container 3, and the three-phase shaft 15 is also connected to a piston 16. The three-phase shaft 15 is also connected to the operating part 9 of the vacuum circuit breaker 5, and the opening and closing operation is performed by the driving force of the operating part 9.

[0022] Next, the relationship between the operation of the vacuum circuit breaker 5 and the volume of the piston container 16a of the piston device 160 will be described using Figures 2 to 6. Figure 2 shows the open position of the vacuum circuit breaker 5, where the movable contact 10a and fixed contact 10b of the vacuum interrupter 10 are separated. Figure 3 shows the closed position of the vacuum circuit breaker 5, where the movable contact 10a and fixed contact 10b of the vacuum interrupter 10 are in contact. As can be seen from comparing Figures 2 and 3, the three-phase shaft 15 moves upward in Figure 3 compared to Figure 2, so that the movable part 12 of the vacuum circuit breaker 5 also moves upward, and the movable contact 10a of the vacuum interrupter 10 comes into contact with the fixed contact 10b of the vacuum interrupter 10.

[0023] As shown in FIG. 3, the bellows dimension 11a of the vacuum interrupter 10 is in an expanded state. Furthermore, the contact pressure spring dimension 14a of the contact pressure spring 14 is in a compressed, short state. Furthermore, as the three-phase shaft 15 moves upward, the piston 16 also moves upward. As a result, the piston container dimension 16b is shorter in FIG. 3 than in FIG. 2. If the movement distance of the three-phase shaft 15 when the vacuum circuit breaker 5 is opened or closed is R, the movement distance of the piston 16 is also R, and the increase or decrease in the piston container dimension 16b is also R. Furthermore, if the contact pressure spring dimension 14a when the vacuum circuit breaker 5 is closed is W, and the compressed dimension of the contact pressure spring 14 when the vacuum circuit breaker 5 is closed relative to when the vacuum circuit breaker 5 is opened is Y, then the dimension of the contact pressure spring 14 when the vacuum circuit breaker 5 is opened is W+Y.

[0024] Furthermore, the separation dimension between the movable contact 10a of the vacuum interrupter 10 and the fixed contact 10b of the vacuum interrupter 10 when the vacuum interrupter 5 is open is defined as Z. The movable part 12 of the vacuum interrupter 5 moves by Z. When the vacuum interrupter 5 operates from the open position to the closed position, the three-phase shaft 15 moves by R, and at this time the movable part 12 of the vacuum interrupter 5 moves by Z, bringing the movable contact 10a of the vacuum interrupter 10 into contact with the fixed contact 10b of the vacuum interrupter, after which the contact pressure spring 14 is compressed by Y. Therefore, R = Z + Y. Furthermore, if the internal dimension of the piston container 16a when the vacuum interrupter 5 is closed is defined as V, the internal dimension of the piston container 16a when the vacuum interrupter 5 is open is V + R. The above can be summarized as shown in Figure 4.

[0025] Furthermore, if the cross-sectional area of ​​the bellows 11 of the vacuum valve 10 is S and the internal cross-sectional area of ​​the piston container 16a is P, the internal volume of the bellows 11 of the vacuum valve 10 and the internal volume of the piston container 16a are as shown in FIG.

[0026] In other words, without the piston container 16a, the volume of the gas compartment 19 including the bellows 11 of the vacuum valve 10 would be reduced by 3×S×Z when the vacuum circuit breaker 5 is open compared to when it is closed, which would increase the pressure.

[0027] On the other hand, when the piston container 16a is provided as in the present disclosure, the internal volume of the piston container 16a increases by P×R when the vacuum circuit breaker 5 is open compared to when it is closed. Therefore, by installing the piston container 16a with dimensions such that 3×S×Z=P×R, it is possible to suppress increases and decreases in the volume and pressure of the gas compartment 19 including the bellows 11 of the vacuum valve 10 even when the vacuum circuit breaker 5 is opened or closed.

[0028] Here, we have described an example of a piston container 16a with dimensions such that 3×S×Z=P×R. However, even if 3×S×Z and P×R are not identical, as long as they are fairly close in value, it is possible to suppress increases and decreases in the volume and pressure of the gas compartment 19 including the bellows 11.

[0029] As an example of a value that is relatively close, if the volume of the entire gas compartment including the bellows of the vacuum valve 10 when the contact is closed is C and the pressure is A, then when the contact is opened, the volume is (C + P * R - 3 * S * Z) and the pressure is B. If it is desired to control B to within ±10% of A, then B = A * C / (C + P * R - 3 * S * Z), and therefore various dimensions can be set so that C / (C + P * R - 3 * S * Z) is a predetermined value, for example, the same, 1.0, or 0.9 to 1.1 within the concept of the same. However, this is not a limitation, and the volume difference between the piston device and the volume difference due to expansion and contraction of the bellows between the closed and open states of the vacuum valve may be set to a predetermined volume difference as appropriate depending on the device characteristics.

[0030] According to the gas-insulated switchgear of the first embodiment configured as described above, In a gas-insulated switchgear equipped with a vacuum circuit breaker, The vacuum circuit breaker comprises: Vacuum valve and a fixed contact fixed inside the vacuum valve; a movable contact arranged opposite the fixed contact; a bellows that moves in conjunction with the movement of the movable contact; the vacuum valve has a vacuum compartment in which the fixed contact and the movable contact are disposed, and a gas compartment containing the bellows; The piston device is connected to the gas compartment and has a preset volume difference that is equal to the volume difference caused by the expansion and contraction of the bellows between the closed and open states of the vacuum valve. The piston device offsets the difference in volume of the gas compartment containing the bellows due to the opening and closing of the vacuum valve, thereby suppressing increases and decreases in pressure in the gas compartment containing the bellows. By providing a piston device whose volume increases and decreases in accordance with the operation of the moving contacts of the vacuum circuit breaker, the volume of the gas compartment containing the bellows of the vacuum valve does not change even when the vacuum circuit breaker is opened or closed. Maintaining a constant volume of the gas compartment containing the bellows of the vacuum valve regardless of the opening or closing state of the vacuum circuit breaker keeps the pressure in the gas compartment containing the bellows of the vacuum valve constant, thereby stabilizing the insulation performance of the gas compartment containing the bellows of the vacuum valve, stabilizing the stress the bellows receives due to pressure, and further reducing the load on the operating part of the vacuum circuit breaker due to pressure. This provides a gas-insulated switchgear that prevents a decrease in insulation performance and reduces the load on the vacuum circuit breaker.

[0031] Furthermore, according to the gas-insulated switchgear of the first embodiment configured as described above, The piston device is connected to the gas compartment and has a volume difference equal to the volume difference caused by expansion and contraction of the bellows between the closed and open states of the vacuum valve. The difference in volume of the gas compartment in which the bellows is located due to the opening and closing of the vacuum valve can be reliably offset by the piston device, and the increase or decrease in pressure in the gas compartment in which the bellows is located can be reliably suppressed.

[0032] Embodiment 2 Fig. 6 is a schematic plan view of the configuration of a vacuum circuit breaker of a gas-insulated switchgear according to embodiment 2, as viewed from above. Fig. 7 is a diagram showing the configuration of a piston device of the vacuum circuit breaker shown in Fig. 6. In the figure, the same parts as those in embodiment 1 above are given the same reference numerals, and descriptions thereof will be omitted. Furthermore, in embodiment 2, descriptions will be mainly focused on parts that are different from embodiment 1 above, and descriptions of similar parts will be omitted as appropriate.

[0033] 2 and 3 of the first embodiment are schematic diagrams of the vacuum circuit breaker 5 as seen from the front, and for convenience, the vacuum interrupter 10 and piston device 160 are shown side by side. In reality, as shown in Fig. 6, when viewed from above, the shafts of the three-phase vacuum interrupters 10 are arranged at the vertices of a triangle on a plane. The shaft of the piston 16 is arranged at the center of the triangle in which the vacuum interrupters 10 are arranged, and is formed to communicate with it. The shafts of the three-phase vacuum interrupters 10 are also connected by a three-way three-phase shaft 15.

[0034] 7, a bearing portion 20 is disposed between the piston 16 and the piston container 16a. As a result, when the three-phase shaft 15 operates the three-phase vacuum interrupter 10, the movement direction of the three-phase shaft 15 is supported by the bearing portion 20. This prevents the three-phase shaft 15 from tilting relative to the vertical direction. This also reduces operational variations in the bellows 11 of the three-phase vacuum interrupter 10 of the vacuum circuit breaker 5.

[0035] The gas-insulated switchgear of the second embodiment configured as described above has the same effects as those of the first embodiment, and also has the following advantages: The vacuum circuit breaker has the vacuum valves for three phases, The three-phase vacuum valve has its axes arranged at the vertices of a triangle on a plane, The piston axis of the piston device is disposed at the center of the triangle in which the vacuum valves are disposed, and is formed in communication with the three-phase vacuum valves, It can also be used in cases where a three-phase vacuum valve is provided.

[0036] Furthermore, according to the gas-insulated switchgear of the second embodiment configured as described above, the same effects as those of the first embodiment can be achieved, and in addition, The piston of the piston device is provided with a bearing portion, so that tilting in the vertical direction can be suppressed, and the operational variation of the bellows of the three-phase vacuum valve can be suppressed.

[0037] Embodiment 3 Figure 8 is a diagram showing the configuration of a piston device of a vacuum circuit breaker of a gas-insulated switchgear according to embodiment 3. In the figure, parts that are the same as those in the above-mentioned embodiments are given the same reference numerals and descriptions thereof will be omitted. Furthermore, in this embodiment 3, the description will focus on parts that are different from the above-mentioned embodiments, and descriptions of similar parts will be omitted as appropriate.

[0038] In the gas-insulated switchgear 1, an insulating gas such as SF6 gas or dry air is sealed inside the container. However, if moisture is present inside the container, it will affect the deterioration of the internal components, so it is necessary to adsorb the moisture using an adsorbent. In the third embodiment, as shown in FIG. 8, an adsorbent 21 that adsorbs moisture is disposed in the internal space of the piston container 16a. This allows the piston container 16a to also be used as an arrangement space for the adsorbent 21. Therefore, there is no need to provide a separate arrangement space for the adsorbent 21, and the space inside the sealed container can be used effectively.

[0039] The gas-insulated switchgear of the third embodiment configured as described above has the same effects as those of the above-described embodiments, and also has the following advantages: The piston device has a moisture adsorbent inside, The space inside the vacuum circuit breaker container can be used effectively.

[0040] 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 contemplated 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, and even cases where at least one component is extracted and combined with components of other embodiments. [Explanation of symbols]

[0041] 1 Gas insulated switchgear, 2a, 2b, 2c Sealed enclosure for disconnecting switch, 3 Sealed enclosure for circuit breaker, 4a, 4b, 4c Disconnecting switch earthing switch, 5 Vacuum circuit breaker, 6a, 6b, 6c Bushing, 7a, 7b, 7c Cable, 8 Busbar, 9 Operating part, 10 Vacuum valve, 10a Moving contact, 10b Fixed contact, 11 Bellows, 11a Bellows dimensions, 12 Moving part, 13 Insulating tube, 14 Pressure spring, 14a Pressure spring dimensions, 15 Three-phase shaft, 16 Piston, 160 Piston device, 16a Piston container, 16b Piston container dimensions, 17 Flange, 18 Gas compartment, 19 Gas compartment, 20 Bearing part, 21 Adsorbent, 22 Vacuum compartment.

Claims

1. In a gas-insulated switchgear equipped with a vacuum circuit breaker, The vacuum circuit breaker comprises: Multiple vacuum valves and Each of the vacuum valves has: a fixed contact fixed inside the vacuum valve; a movable contact arranged opposite the fixed contact; a bellows that moves in conjunction with the movement of the movable contact; Each of the vacuum valves has a vacuum compartment in which the fixed contact and the movable contact are disposed, and a gas compartment containing the bellows, A gas-insulated switchgear comprising one piston device connected to all of the gas compartments and having a preset volume difference that is the same as all of the volume differences that occur when the bellows expands and contracts between the closing and opening states of each of the vacuum valves.

2. 2. The gas-insulated switchgear according to claim 1, wherein the piston device is connected to the gas compartment and has a volume difference equal to the volume difference caused by expansion and contraction of the bellows between the closed and open states of the vacuum valve.

3. The vacuum circuit breaker has the vacuum valves for three phases, The three-phase vacuum valve has its axes arranged at the vertices of a triangle on a plane, 2. The gas-insulated switchgear according to claim 1, wherein the axis of the piston of the piston device is arranged at the center of the triangle in which the vacuum valves are arranged, and is formed to communicate with the three-phase vacuum valves.

4. The vacuum circuit breaker has three phases of the vacuum valves, The three-phase vacuum valve has its axes arranged at the vertices of a triangle on a plane, 3. The gas-insulated switchgear according to claim 2, wherein the axis of the piston of the piston device is arranged at the center of the triangle in which the vacuum valves are arranged, and is formed to communicate with the three-phase vacuum valves.

5. The gas-insulated switchgear according to claim 3 , wherein the piston of the piston device is provided with a bearing portion.

6. A gas-insulated switchgear as described in Claim 4, wherein the piston of the piston device is provided with a bearing portion.

7. 7. The gas-insulated switchgear according to claim 1, wherein the piston device includes a moisture adsorbent therein.

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