JP4545362B2 - Gas insulated switchgear - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a gas-insulated switchgear in which switchgear such as a circuit breaker, a disconnect switch, and a ground switch is housed in a container and filled with an insulating gas such as dry air or nitrogen gas.
[0002]
[Prior art]
SF ₆ gas, which is widely used as an insulating medium for electrical equipment, was designated as an emission suppression gas at the Kyoto Conference on Global Warming Prevention in 1997. In the future, the use of SF ₆ gas will be restricted for gas insulated switchgear. Gas-insulated switchgear that does not use any SF ₆ gas has been developed and put into practical use. For example, as a 24 kV class gas insulated switchgear, there is one shown in the document “SF ₆ gas-free new type 24 kV switchgear” (published in the March 2001 issue of Electrical Review).
[0003]
FIG. 3 shows the overall configuration of the gas-insulated switchgear and FIG. 4 shows the configuration of the blocking portion. In the figure, 1a, 1b and 1c are vacuum switches, 2a, 2b and 2c are line-side disconnectors, 3a, 3b and 3c are insulating operation rods for opening and closing the vacuum switches 1a, 1b and 1c, and 4a, 4b and 4c are connected. Conductors, 5a, 5b and 5c are connection bushings, 6 is a vacuum switch 1a, 1b and 1c, a disconnector 2a, 2b and 2c, a breaker container containing operation rods 3a, 3b and 3c, and 7 is a vacuum switch 1a, 1b, 1c is a shut-off portion operating mechanism for opening and closing 10 and 10 is a portion in which the shut-off portion container 6 accommodates vacuum switches 1a, 1b, 1c, line side disconnectors 2a, 2b, 2c, operating rods 3a, 3b, 3c, etc. And the blocking bushes 5a, 5b, and 5c, the blocking unit operating mechanism 7, and the line side bushings 8a, 8b, and 8c. Reference numerals 9a, 9b, 9c are insulated conductors connecting the line-side bushings 8a, 8b, 8c and the lines.
[0004]
22a, 22b, and 22c are bus-side disconnectors, 23a, 23b, and 23c are bus-side bushings that are connected to the bus, 26 is a bus-side disconnector container that houses the bus-side disconnectors 22a, 22b, and 22c, and 27 is a bus side This is a bus-side disconnector operating mechanism for operating the disconnectors 22a, 22b, and 22c. Reference numeral 20 denotes a bus-side disconnector unit composed of bus-side disconnectors 22a, 22b, 22c and a bus-side disconnector operating mechanism 27 accommodated in the bus-side disconnector container 26. Reference numeral 29 denotes a housing that houses the blocking unit 10 and the busbar side disconnector unit 20. Reference numeral 30 denotes a gas-insulated switchgear in which the blocking unit 10, the busbar side disconnecting unit 20, and other devices are accommodated in a casing 29.
[0005]
As shown in FIG. 4 of the block diagram of the vacuum switch 1a, 1b, 1c as viewed from the axial direction, the internal structure of the shut-off unit 10 is arranged on both sides of the vacuum switch 1a, 1c, and the central phase vacuum switch 1b is In this configuration, the insulating barriers 11a, 11b, and 11c are arranged between the phases. The gas insulated switchgear 30 is provided with a ground switch at a position hidden behind the illustrated portion.
[0006]
In the gas insulated switchgear 30 configured as described above, the breaker 10 is accommodated in the breaker part container 6 and the busbar side disconnector part 20 is accommodated in the busbar side disconnector part container 26, respectively. It is a configuration in which an insulating gas of about 8: 2 with a mixing ratio of dry air or nitrogen and oxygen equivalent to that of dry air is filled at a pressure slightly higher than the atmospheric pressure, and an insulation barrier is provided between the ground of each phase charging part and between the phases. By arranging it, it is realized as a gas insulated switchgear that is not inferior in dimension to the case of using SF ₆ gas without using SF ₆ gas having a large global warming potential.
[0007]
In the gas insulated switchgear 30 configured in this way, switchgears such as vacuum switches 1a, 1b, 1c, line-side disconnectors 2a, 2b, 2c are accommodated in the circuit breaker section container 6, and the busbar side is similarly busbar The side disconnectors 22a, 22b, and 22c are accommodated in the bus side disconnector section container 26 and filled with insulating gas. If there is a leak in each container 6 or 26, the insulation performance cannot be maintained. Is manufactured under strict control so that no gas leakage occurs, and when the switchgear is built in, helium gas is filled inside for leak inspection and the surroundings of the container are inspected. Place in a container and secure a state lower than the filling pressure of helium gas by evacuation or the like, hold it for a predetermined time, and detect the presence and concentration of helium gas in the cuvette with a helium gas detector It is doing a leakage inspection Te.
[0008]
Since the helium gas filled for the leak inspection cannot be grasped about the influence on the withstand voltage performance when remaining in the container, the inside of the container 6 or 26 in which the switchgear is accommodated is evacuated after the leak inspection. Then, the helium gas is extracted, and the dry gas or an insulating gas having a mixing ratio of nitrogen and oxygen equivalent to that of dry air is approximately 8: 2 at a predetermined pressure.
[0009]
[Problems to be solved by the invention]
In the conventional air-insulated gas-insulated switchgear described above, helium gas is filled in a container in which the switchgear is housed, and a leak test is performed with the surroundings of the container 6 or 26 in which the switchgear is housed in a decompressed state. After inspecting, the inside of the container filled with helium gas is evacuated to extract helium gas, and the dry air or an insulating gas having a mixing ratio of nitrogen and oxygen equivalent to that of dry air is filled to a predetermined pressure. Then, after the leak inspection, there is a work of evacuating the container 6 or 26 and a work of filling with an insulating gas, and there is a problem that the assembling work time is long and the manufacturing cost is high.
[0010]
The present invention clarifies the influence on the withstand voltage performance of the helium gas filled for the leak inspection in the container in which the switchgear is accommodated, and the filled helium gas remains in the container and has a predetermined pressure. An object of the present invention is to provide a gas-insulated switchgear in which an insulating gas having a mixing ratio of approximately 8: 2 that is equal to dry air or a mixing ratio of nitrogen and oxygen is filled to a predetermined pressure.
[0011]
[Means for Solving the Problems]
In the gas insulated switchgear according to claim 1 of the present invention, an opening / closing device is accommodated in a container, and the insulating gas of the gas insulated switchgear used when the container is filled with an insulating gas is filled at the time of leak inspection of the container. In addition to the helium gas thus formed, an insulating gas having a mixing ratio of dry air or nitrogen and oxygen of approximately 8: 2 equivalent to that of dry air is filled at a gas pressure higher than atmospheric pressure.
[0012]
According to a second aspect of the present invention, the gas insulated switchgear according to the second aspect of the present invention uses helium gas to be filled at the time of leak inspection of the container having the configuration of the first aspect. In such a state, the partial pressure ratio in the state filled with the insulating gas is filled in an amount of 3 to 15%.
[0013]
According to a third aspect of the present invention, the gas insulated switchgear according to the third aspect of the present invention uses helium gas to be filled at the time of the leak inspection of the container of the first aspect. In such a state that the partial pressure ratio is 3 to 7% in the state filled with the insulating gas.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
In the first embodiment, the amount of helium gas necessary for leak inspection is left without changing the configuration of the gas-insulated switchgear that does not use SF ₆ gas, a global warming gas whose use is restricted, and dry air or It can be used in a state of being filled with an insulating gas having a mixing ratio of nitrogen and oxygen of about 8: 2, which is equivalent to that of dry air.
[0015]
Focusing on the fact that the assembly time can be shortened if it can be filled with dry air or a mixed gas of nitrogen and oxygen at a predetermined pressure without removing the helium gas filled for leak inspection after leak inspection. The experiment was conducted.
FIG. 1 and FIG. 2 show the results of determining the breakdown voltage by changing the mixing ratio of helium gas necessary for leak inspection to an insulating gas of about 8: 2 in which the mixing ratio of nitrogen and oxygen is equivalent to that of dry air. FIG. 1 shows a helium gas gas with a lightning impulse breakdown voltage of 1.0 when the electrode-to-electrode distance between the rod electrode and the plate electrode with a radius of curvature of 25 mm is 30 mm, the gas pressure is 0.25 MPa, and the mixing ratio of helium gas is 0. This shows the relationship between the mixing ratio and the breakdown voltage. FIG. 2 shows that the distance between the electrode of a rod electrode having a radius of curvature of 10 mm and a plate electrode is 60 mm, an insulating barrier having a thickness of 10 mm is arranged in the middle of the electrode at a distance of 15 mm from the rod electrode and 35 mm from the plate electrode. The lightning impulse breakdown voltage when the helium gas mixture ratio is 0 is set to 0.20 MPa, and the relationship between the helium gas mixture ratio and the breakdown voltage is shown as 1.0.
[0016]
As a result, in FIG. 1, when the helium gas partial pressure ratio is up to 45%, the breakdown voltage is higher than when helium gas is not included, and when the partial pressure ratio is 5%, the maximum value is 1.15 times. In FIG. 2, the breakdown voltage is higher when the partial pressure ratio is 15% or less than when helium gas is not included, and in the range of 3 to 7%, the breakdown voltage is 1.05 times that when helium gas is not included. ing.
[0017]
Based on the above results, helium gas to be filled for leak inspection is filled with helium gas in an amount such that the partial pressure ratio of the gas-insulated switchgear to the insulating gas is 15% or less. By filling with an insulating gas having a mixing ratio of approximately 8: 2 that is equal to that of dry air or a dry air or a mixture ratio of nitrogen and oxygen, a gas-insulated switchgear having a dielectric strength equivalent to that without helium gas is obtained. .
[0018]
In addition, helium gas to be filled for leak inspection is filled with a partial pressure ratio in the range of 3 to 7% with respect to the insulating gas of the gas insulated switchgear, and leak inspection is performed. Filling with an insulating gas of approximately 8: 2 with dry air or a mixture ratio of nitrogen and oxygen equal to that of dry air up to a pressure increases the dielectric strength by 1.05 times compared to the case where helium gas is not included, It becomes a gas insulated switchgear with high insulation reliability.
[0019]
The leak inspection performed after the opening / closing device is incorporated in the container 6 or 26 of the gas insulated switchgear is filled with a helium gas in an amount necessary for the leakage inspection in the container in which the opening / closing device is accommodated. Leaked by a method of detecting the presence of helium gas and the concentration of helium gas in the vacuum container by holding the vacuum state for a predetermined period of time and putting it in a vacuum container so that the pressure is lower than the helium gas filling pressure. Perform an inspection. After the leak inspection, the air 6 or 26 in which the switchgear is accommodated is left with helium gas remaining, and dry air or an insulating gas having a nitrogen / oxygen mixing ratio of about 8: 2 equivalent to dry air at a predetermined pressure. Filled and assembled.
[0020]
For example, a gas filling inspection apparatus shown in FIG. 3 is prepared and the leakage inspection is performed by this apparatus, whereby the leakage inspection and the filling operation of the insulating gas can be performed efficiently. In FIG. 3, 31 is a vacuum vessel, 32 is a helium gas detection device, 33 is a valve provided in the gas insulated switchgear 10 or 20, 34 is a valve provided in a pipe penetrating the wall of the vacuum vessel 31, and 35 is a vacuum. A valve provided in the container 31, 36 is a valve provided in a pipe connected to a vacuum pump, 37 is a valve connected to a helium gas cylinder, 38 is a dry air tank or a mixing ratio of nitrogen and oxygen is equal to dry air A valve 39 connected to a tank of insulating gas mixed at approximately 8: 2 is a valve for returning the inside of the vacuum vessel 31 provided in the vacuum vessel 31 to atmospheric pressure.
[0021]
The leak inspection and gas filling operation by the gas filling inspection apparatus shown in FIG.
(A) The assembled gas insulated switchgear 10 or 20 is accommodated in the vacuum vessel 31, the valve 33 and the valve 34 are connected, the valve 33 is opened, and the lid of the vacuum vessel 31 is attached and sealed.
(B) The valves 34 and 35 are opened, the valves 37 and 38 are closed, the vacuum pump is operated and the valve 36 is opened, and the gas insulated switchgear 10 or 20 and the vacuum vessel 31 are opened. Evacuate.
(C) After reaching a predetermined degree of vacuum, the valves 34, 35, and 36 are closed, the valve 38 is maintained closed, the valve 37 is opened, and the valve 34 is opened to supply helium gas. Then, the valves 34 and 37 are closed.
(Predetermined pressure = 3-7% or 3-15% of the total pressure of the gas insulated switchgear)
(D) The state filled with helium gas is maintained for a predetermined time, and the presence or absence of helium gas in the vacuum vessel 31 and the helium gas concentration are detected by the helium gas inspection device 32.
(E) When the detected helium gas value is less than the limit value in (d), it is determined that there is no leakage, and the following operation is performed.
(F) The valves 33 and 34 are opened, the valves 35, 36, and 37 are closed, and the valve 39 is opened to bring the vacuum inside the vacuum vessel 31 to atmospheric pressure.
(G) Confirm the closed state of the valve 35, open the valve 38, open the valve 34, and open the valve 34 with an insulating gas of approximately 8: 2 so that the mixing ratio of dry air or nitrogen and oxygen is equal to that of dry air. A predetermined pressure is filled and the valve 34 is closed.
(H) The lid of the vacuum vessel 31 is removed, the valve 33 is closed, and the gas insulated switchgear is taken out, thereby completing the leak inspection and the gas filling operation.
[0022]
As described above, the helium gas filled for the leak inspection is left in the container and filled with a predetermined pressure of approximately 8: 2 insulating gas in which the mixing ratio of dry air or nitrogen and oxygen is equal to that of dry air. As a result, there is no need to perform evacuation and insulation gas filling after a leak test as in the prior art, and the assembly time can be reduced.
[0023]
【The invention's effect】
In the gas insulated switchgear according to the first aspect of the present invention, the helium gas filled at the time of the container leak inspection is largely filled with an insulating gas having a mixing ratio of 8: 2 that is equal to that of dry air or dry air. Since the filling is performed at a gas pressure higher than the atmospheric pressure, the evacuation work after the leak inspection and the filling work of the insulating gas are eliminated, and the assembling work time can be shortened.
[0024]
According to a second aspect of the present invention, the gas insulated switchgear according to the second aspect of the present invention uses helium gas to be filled at the time of leak inspection of the container having the configuration of the first aspect. Since the partial pressure ratio is 3 to 15% in a state where the insulating gas is filled, there is no need to perform the vacuuming operation after the leakage inspection and the insulating gas filling operation, and the withstand voltage performance is ensured.
[0025]
According to a third aspect of the present invention, the gas insulated switchgear according to the third aspect of the present invention uses helium gas to be filled at the time of the leak inspection of the container of the first aspect. Since the partial pressure ratio in the state filled with the insulating gas is 3 to 7%, the withstand voltage characteristic is improved as compared with the case where helium gas is not included.
[Brief description of the drawings]
FIG. 1 is a breakdown voltage characteristic diagram of an insulating gas obtained by adding helium gas to an insulating gas in which nitrogen and oxygen are mixed.
FIG. 2 is a breakdown voltage characteristic diagram when an insulating barrier is disposed between electrodes of an insulating gas obtained by adding helium gas to an insulating gas in which nitrogen and oxygen are mixed.
FIG. 3 is a conceptual diagram of a gas filling leak inspection apparatus.
FIG. 4 is a configuration diagram of a conventional 24 kV class gas insulated switchgear using dry air as an insulating medium.
FIG. 5 is a detailed configuration diagram of the blocking unit of FIG. 4;
[Explanation of symbols]
31 vacuum vessel, 32 helium gas detector, 33-39 valve.

Claims (3)

In a gas-insulated switchgear in which an opening / closing device is accommodated in a container, and the container is filled with an insulating gas, the insulating gas includes dry air or nitrogen and oxygen in addition to the helium gas filled at the time of leakage inspection of the container. A gas-insulated switchgear characterized in that an insulating gas having a mixing ratio of approximately 8: 2 equivalent to that of dry air is filled at a gas pressure higher than atmospheric pressure. The amount of helium gas to be filled at the time of the container leakage inspection is such that the partial pressure ratio is 3 to 15% in a state in which dry air or a mixture ratio of nitrogen and oxygen is approximately 8: 2 equivalent to that of dry air. The gas insulated switchgear according to claim 1, wherein the gas insulated switchgear is filled. The amount of helium gas to be filled at the time of the container leakage inspection is such that the partial pressure ratio is 3 to 7% in the state where the dry air or the mixing ratio of nitrogen and oxygen is approximately 8: 2 equivalent to that of dry air. The gas insulated switchgear according to claim 1, wherein the gas insulated switchgear is filled.

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