A mixed insulation gas charging device and a charging method

Abstract

The application discloses a kind of mixed insulation gas charging device and charging method, belong to electrical equipment insulation gas field, solve the existing charging device only to single mixed insulation gas is carried out charging and the problem that mixed insulation gas mixing ratio appears deviation when charging steel bottle is connected reversely;By detecting the pressure of mixed insulation gas in buffer tank, compared with reference pressure value test calibration value, judge whether the mixed insulation gas filled is SF6 / N2 or C4F7N / CO2, can identify the gas type of two charging gas paths respectively passed in;According to the test result, mass flow controller automatically selects the mass flow conversion coefficient corresponding to the gas type of current charging gas path, and in mixed ratio detection module automatically switches to the mixed ratio detection mode of current mixed insulation gas to be charged, to ensure that the mixed ratio of mixed insulation gas in charging chamber meets the requirements;The application is suitable for SF6 / N2 and C4F7N / CO2 two kinds of mixed insulation gas preparation and charging.

Description

Technical Field

[0001] This invention belongs to the field of electrical equipment insulating gas technology, and relates to a mixed insulating gas replenishment device and replenishment method. Background Technology

[0002] Gas-insulated equipment is one of the key transmission and transformation equipment that cannot be replaced by modern power grids. It has the advantages of compact structure, low susceptibility to environmental factors, and high operational safety and reliability. SF6 / N2 and C4F7N / CO2 mixed insulating gases are the most widely used insulating media in the power industry due to their excellent insulation and arc-extinguishing properties.

[0003] In engineering applications, the mixing ratio of the two insulating gases SF6 / N2 and C4F7N / CO2 is usually set as follows: the mixing ratio range of SF6 / N2 is SF6:N2 = (29%~31%): (71%~69%); the mixing ratio range of C4F7N / CO2 is C4F7N:CO2 = (5%~15%): (95%~85%).

[0004] Currently, mature SF6 / N2 and C4F7N / CO2 filling devices are available on the market. For example, Chinese invention patent application CN108119749A, published on June 5, 2018, discloses an SF6 and N2 mixed gas filling device and a precise filling method. This invention uses a gas mass flow controller to precisely control the mixing ratio of the mixed insulating gases and controls the filling speed and amount of SF6 and N2 gases based on the detected gas composition content in the gas chamber of GIS electrical equipment. Chinese invention patent application CN110314565A, published on October 11, 2019, discloses a multifunctional C4F7N / CO2 mixed gas mixing system and method. This invention uses a dynamic gas distribution pipeline structure and a pressure-partitioned mixing pipeline structure to quantitatively and pressure-controlled mix heated C4F7N and CO2 respectively. However, the above two devices can only replenish a single mixed insulating gas and cannot be applied to both SF6 / N2 and C4F7N / CO2 mixed insulating gases at the same time.

[0005] In addition, due to operational errors and unclear cylinder markings, SF6 cylinders and N2 cylinders or C4F7N cylinders and CO2 cylinders are often connected in reverse during on-site gas filling, resulting in incorrect gas type connection. This causes the type of gas being filled to differ from the set gas type, leading to a deviation in the mixing ratio of the mixed insulating gas. Summary of the Invention

[0006] This invention addresses the problems of existing gas filling devices being able to fill only a single mixed insulating gas and the deviation in the mixing ratio of the mixed insulating gas caused by the cylinder being connected incorrectly during filling.

[0007] The present invention solves the above-mentioned technical problems through the following technical solutions: A mixed insulating gas filling device includes: a first gas path, a second gas path, a mixing device, a vacuuming device, a mixing ratio detection unit, and a filling unit; the first gas path includes: a first gas cylinder (10), a first pressure reducing valve (11), a first heat exchanger (12), a first solenoid valve (13), a second solenoid valve (14), and a first mass flow controller (15); the second gas path includes: a second gas cylinder (20), a second pressure reducing valve (21), a second heat exchanger (22), a third solenoid valve (23), a fourth solenoid valve (24), and a fifth solenoid valve (25). The mass flow controller (25) is a second mass flow controller. The mixing device includes a buffer tank (30), a first compressor (31), a first temperature sensor (32), and a first pressure sensor (33). The vacuuming device includes a vacuum pump (40), a fifth solenoid valve (41), and a vacuum gauge (42). The mixing ratio detection unit includes a mixing ratio detection device (50) and a proportional valve (51). The gas filling unit includes a second compressor (60), a sixth solenoid valve (61), a second pressure sensor (62), and a gas filling port (63). The input end of the first pressure reducing valve (11) is sealed to the first steel cylinder (10) through a pipe, the output end of the first pressure reducing valve (11) is sealed to the input end of the first heat exchanger (12) through a pipe, the output end of the first heat exchanger (12) is sealed to the input end of the first solenoid valve (13) through a pipe, and the output end of the first solenoid valve (13), the input end of the second solenoid valve (14), and the input end of the first mass flow controller (15) are sealed to each other through a three-way pipe. The input end of the second pressure reducing valve (21) is sealed to the second steel cylinder (20) through a pipe, the output end of the second pressure reducing valve (21) is sealed to the input end of the second heat exchanger (22) through a pipe, the output end of the second heat exchanger (22) is sealed to the input end of the third solenoid valve (23) through a pipe, and the output end of the third solenoid valve (23), the input end of the fourth solenoid valve (24), and the input end of the second mass flow controller (25) are sealed to each other through a three-way pipe. The output ends of the second solenoid valve (14) and the fourth solenoid valve (24) are connected by a sealed pipe. The output ends of the first mass flow controller (15) and the second mass flow controller (25) are connected by a sealed pipe. The pipe between the output ends of the second solenoid valve (14) and the fourth solenoid valve (24) is connected to the pipe between the output ends of the first mass flow controller (15) and the second mass flow controller (25), and is sealed to the input end of the buffer tank (30). The output end of the buffer tank (30) is sealed to the input end of the second compressor (60) through a pipe. The output end of the second compressor (60) is sealed to the input end of the sixth solenoid valve (61) through a pipe. The output end of the sixth solenoid valve (61) is sealed to the air inlet (63) through a pipe. The second pressure sensor (62) is sealed and installed on the pipe at the output end of the sixth solenoid valve (61). The input end of the proportional valve (51) is sealed to the output end of the buffer tank (30) through a pipe, the output end of the proportional valve (51) is sealed to the input end of the mixing ratio detection device (50) through a pipe, and the output end of the mixing ratio detection device (50) is sealed to the input end of the second compressor (60) through a pipe. The input end of the fifth solenoid valve (41) is sealed and connected to the pipeline between the output end of the buffer tank (30) and the input end of the second compressor (60) through a pipe. The output end of the fifth solenoid valve (41) is sealed and connected to the input end of the vacuum pump (40) through a pipe. The vacuum gauge (42) is sealed and installed on the pipeline between the output end of the fifth solenoid valve (41) and the input end of the vacuum pump (40).

[0008] A method for replenishing gas using the aforementioned mixed insulating gas replenishing device includes the following steps: Step 1: Calibration of reference pressure value of mixed insulating gas; Step 2: Evacuate the device; Step 3: Identify the type of gas being filled and determine the inflation status; Step 4: Preparation and compensation of mixed insulating gas; Step 5: Detect the mixing ratio and inflate.

[0009] Furthermore, the method for calibrating the reference pressure value of the mixed insulating gas described in step 1 is as follows: (1) The test conditions are set as follows: the temperature is 20℃, the value Q1 of the first mass flow controller (15) is set to 30L / min, the value Q2 of the second mass flow controller (25) is set to 70L / min, and the charging time of the first gas path and the second gas path is set to 30s. (2) When the gas in the first gas path is SF6 and the gas in the second gas path is N2, the pressure of the calibrated buffer tank (30) is P1=0.5000MPa; when the gas in the first gas path is N2 and the gas in the second gas path is SF6, the pressure of the calibrated buffer tank (30) is P2=0.6615MPa; when the gas in the first gas path is C4F7N and the gas in the second gas path is CO2, the pressure of the calibrated buffer tank (30) is P3=0.9941MPa; when the gas in the first gas path is CO2 and the gas in the second gas path is C4F7N, the pressure of the calibrated buffer tank (30) is P4=1.1870MPa.

[0010] Further, the method for evacuating the device described in step 2 is as follows: Open the first solenoid valve (13), the second solenoid valve (14), the third solenoid valve (23), the fourth solenoid valve (24), and the fifth solenoid valve (41), start the vacuum pump (40) to evacuate the entire device to 133 Pa, then turn off the vacuum pump (40), let the device stand for 30 minutes and then read the vacuum value X of the vacuum gauge (42), and let it stand for another 5 hours and then read the vacuum value Y of the vacuum gauge (42). The increase value (YX) should not exceed 67 Pa, and the evacuation is considered to be qualified; after the evacuation is completed, close the first solenoid valve (13), the second solenoid valve (14), the third solenoid valve (23), the fourth solenoid valve (24), and the fifth solenoid valve (41).

[0011] Furthermore, when filling the gas chamber of electrical equipment with a mixed SF6 / N2 insulating gas, the method for identifying the type of gas being filled and determining the filling status described in step 3 is as follows: (1) Adjust the first pressure reducing valve (11) and the second pressure reducing valve (21) to 0.6MPa, set the value Q1 of the first mass flow controller (15) to 30L / min and the inflation time to 30s, set the value Q2 of the second mass flow controller (25) to 70L / min and the inflation time to 30s, open the first solenoid valve (13) and the third solenoid valve (23), and the two inflation gases, SF6 and N2, enter the buffer tank (30) and are mixed by the first compressor (31). Record the pressure P in the buffer tank (30) at this time. a1 and temperature ; (2) P a1 When converted to isodense, the pressure P at 20°C b1 The specific calculation process is as follows: According to Dalton's law of partial pressures, the partial pressures of SF6 and N2 are respectively: (1) In the formula, For SF6 gas partial pressure, The percentage of SF6 gas. The partial pressure of N2 gas, The percentage of N2 gas; Will and temperature Substituting the values ​​into the Beattie-Bridgeman equation of state, calculate the SF6 gas density at this temperature and pressure. as follows: (2) In the formula, For gas density, Kelvin temperature ; Due to the temperature of 20℃ and The SF6 gas in the buffer tank (30) has the same density, therefore the temperature is 20℃, i.e., T1 = 20 + 273.15 and Substituting back into equation (2), we obtain the density as The partial pressure of SF6 gas at a temperature of 20℃, i.e., T1 = 20 + 273.15. ; Will Substituting into the ideal gas law, calculate the partial pressure of N2 gas at 20℃: (3) In the formula, This represents the pressure value of N2 gas at 20°C under isodense conditions. , =293.15K.

[0012] Transformed and The sum is the pressure P of the SF6 / N2 mixed insulating gas at 20℃. b1 .

[0013] (3) Compare the pressure P of the mixed insulating gas at 20℃ b1 Calibration value of mixed insulating gas pressure test: If P b1 The closest to P1 is the inflation configuration: the first gas path is filled with SF6, and the second gas path is filled with N2; if P b1 The closest to P2 is filled with N2 gas in the first gas path and SF6 gas in the second gas path.

[0014] Furthermore, the method for preparing and compensating the mixed insulating gas described in step 4 is as follows: When the gas in the first gas path is SF6 and the gas in the second gas path is N2, the first gas cylinder (10) and the second gas cylinder (20) are not reversed. At this time, SF6:N2=30%:70% meets the mixing ratio requirement. No gas compensation is performed. SF6 and N2 are continued to be added to the buffer tank (30) to prepare a mixed insulating gas. When the gas supplied through the first gas line is N2 and the gas supplied through the second gas line is SF6, the first cylinder (10) and the second cylinder (20) are connected in reverse, the preparation of the mixed insulating gas stops, and the amount of gas to be compensated is [not specified]. for: (4) In the formula, This refers to the amount of SF6 gas. This refers to the amount of N2 gas. The proportional coefficient for the SF6 mass flow controller. The inflation time is 30 seconds. After gas compensation, the value Q1 of the first mass flow controller (15) is set to 70L / min, and the value Q2 of the second mass flow controller (25) is set to 30L / min. SF6 and N2 are then added to the buffer tank (30) to prepare a mixed insulating gas.

[0015] Further, the method for detecting the mixing ratio and charging in step 5 is as follows: after opening the proportional valve (51), the mixing ratio detection device (50) detects that the mixing ratio of the prepared mixed insulating gas meets the requirements, the sixth solenoid valve (61) is opened, the second compressor (60) is turned on to charge the gas chamber of the electrical equipment, and the second pressure sensor (62) stops charging after detecting that the charging pressure reaches the rated pressure of the gas chamber.

[0016] Furthermore, when filling the gas chamber of electrical equipment with a C4F7N / CO2 mixed insulating gas, the method for identifying the type of gas being filled and determining the filling status described in step 3 is as follows: (1) Adjust the first pressure reducing valve (11) and the second pressure reducing valve (21) to 0.6MPa, set the value Q1 of the first mass flow controller (15) to 30L / min and the inflation time to 30s, set the value Q2 of the second mass flow controller (25) to 70L / min and the inflation time to 30s, open the first solenoid valve (13) and the third solenoid valve (23), and the two inflation gases enter the buffer tank and are mixed by the first compressor (31). Record the pressure P in the buffer tank (30) at this time. a2 and temperature .

[0017] (2) P a2 The pressure P at 20°C when converted to equimolar volume b2; The specific calculation process is as follows: According to Dalton's law of partial pressures, the partial pressures of C4F7N and CO2 are respectively: (5) In the formula, For C4F7N gas partial pressure, The proportion of C4F7N gas. For CO2 gas partial pressure, The percentage of CO2 gas; Will and temperature Substitute the values ​​into the Peng-Robinson equation to calculate the molar volume of C4F7N gas at this temperature and pressure. as follows: (6) In the formula, This represents the gas pressure of C4F7N at 20℃. The gas constant is... Kelvin temperature , The molar volume of C4F7N , , These are the correction parameters for the gas in the Peng-Robinson equation. The critical temperature is 385.928 K. For temperature comparison, The critical pressure is set at 2.5028 MPa. The eccentricity factor is 0.47340; Because the temperature is 20℃ and the temperature is The molar volumes of C4F7N gas in the buffer tank (30) are the same, therefore the temperature is 20℃, i.e., T2 = 20 + 273.15 and Substituting back into equation (4), we obtain the molar volume as follows: The partial pressure of C4F7N gas at a temperature of 20℃, i.e., T1 = 20 + 273.15. ; Will Substituting into the ideal gas law, calculate the partial pressure of CO2 gas at 20℃: (7) In the formula, This represents the CO2 gas pressure at 20°C under isodensity conditions. , =293.15K.

[0018] Transformed and The sum is the pressure P of the C4F7N / CO2 mixed insulating gas at 20℃. b2 ; (3) Compare the pressure P of the mixed insulating gas at 20℃ b2 Calibration value of mixed insulating gas pressure test: If P b2 The closest to P3 is the inflation configuration: the first gas path is filled with C4F7N, and the second gas path is filled with CO2; if P b2 The closest to P4 is filled with CO2 in the first gas path and C4F7N in the second gas path.

[0019] Furthermore, the method for preparing and compensating the mixed insulating gas described in step 4 is as follows: When C4F7N is introduced into the first gas line and CO2 is introduced into the second gas line, and the first gas cylinder (10) and the second gas cylinder (20) are not connected in reverse, the amount of gas to be compensated is... for: (8) When CO2 is introduced into the first gas line and C4F7N is introduced into the second gas line, and the first gas cylinder (10) and the second gas cylinder (20) are connected in reverse, the amount of gas to be compensated is... for: (9) In the formula, The gas volume of C4F7N is [missing information]. This refers to the volume of CO2 gas. The proportional gain for the C4F7N mass flow controller. This is the proportional coefficient for the CO2 mass flow controller; After gas compensation, the value Q1 of the first mass flow controller (15) is set to 15L / min, and the value Q2 of the second mass flow controller (25) is set to 85L / min. Then, C4F7N and CO2 are continuously added to the buffer tank (30) to prepare a mixed insulating gas.

[0020] Further, the method for detecting the mixing ratio and charging in step 5 is as follows: after opening the proportional valve (51), the mixing ratio detection device (50) detects that the mixing ratio of the prepared mixed insulating gas meets the requirements, the sixth solenoid valve (61) is opened, the second compressor (60) is turned on to charge the gas chamber of the electrical equipment, and the second pressure sensor (62) stops charging after detecting that the charging pressure reaches the rated pressure of the gas chamber.

[0021] The advantages of this invention are: The device of this invention determines whether the mixed insulating gas being filled is SF6 / N2 or C4F7N / CO2 by detecting the pressure of the mixed insulating gas in the buffer tank and comparing it with a reference pressure value for test calibration. It can identify the types of gas introduced into the two filling gas paths respectively. Based on the detection results, the mass flow controller automatically selects the mass flow conversion coefficient corresponding to the type of gas being filled in the current filling gas path, and automatically switches to the mixing ratio detection mode of the mixed insulating gas to be filled in the mixing ratio detection module, ensuring that the mixing ratio of the mixed insulating gas entering the filling chamber meets the requirements. The device of this invention is suitable for the preparation and replenishment of two mixed insulating gases, SF6 / N2 and C4F7N / CO2. The filling interface of the device does not need to be set with the gas type, and the gas cylinder can be connected to any filling port to prevent accidental connection during on-site filling, which could lead to a deviation in the mixing ratio of the mixed insulating gas due to a difference between the type of gas filled and the set gas type. Attached Figure Description

[0022] Figure 1 This is a structural diagram of the mixed insulating gas replenishment device according to an embodiment of the present invention; Figure 2 This is a flowchart of the mixed insulating gas replenishment method according to an embodiment of the present invention. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments: I. Structural Composition of the Device like Figure 1As shown, the environmentally friendly mixed insulating gas adaptive filling and replenishing device includes: a first gas path, a second gas path, a mixing device, a vacuuming device, a mixing ratio detection unit, and a filling and replenishing unit; the first gas path includes: a first gas cylinder (10), a first pressure reducing valve (11), a first heat exchanger (12), a first solenoid valve (13), a second solenoid valve (14), and a first mass flow controller (15); the second gas path includes: a second gas cylinder (20), a second pressure reducing valve (21), a second heat exchanger (22), a third solenoid valve (23), and a fourth solenoid valve (24). The second mass flow controller (25) is included; the mixing device includes: a buffer tank (30), a first compressor (31), a first temperature sensor (32), and a first pressure sensor (33); the vacuuming device includes: a vacuum pump (40), a fifth solenoid valve (41), and a vacuum gauge (42); the mixing ratio detection unit includes: a mixing ratio detection device (50) and a proportional valve (51); the gas filling unit includes: a second compressor (60), a sixth solenoid valve (61), a second pressure sensor (62), and a gas filling port (63).

[0025] The input end of the first pressure reducing valve (11) is sealed to the first steel cylinder (10) through a pipe, the output end of the first pressure reducing valve (11) is sealed to the input end of the first heat exchanger (12) through a pipe, the output end of the first heat exchanger (12) is sealed to the input end of the first solenoid valve (13) through a pipe, and the output end of the first solenoid valve (13), the input end of the second solenoid valve (14), and the input end of the first mass flow controller (15) are sealed to each other through a three-way pipe. The input end of the second pressure reducing valve (21) is sealed to the second steel cylinder (20) through a pipe, the output end of the second pressure reducing valve (21) is sealed to the input end of the second heat exchanger (22) through a pipe, the output end of the second heat exchanger (22) is sealed to the input end of the third solenoid valve (23) through a pipe, and the output end of the third solenoid valve (23), the input end of the fourth solenoid valve (24), and the input end of the second mass flow controller (25) are sealed to each other through a three-way pipe. The output ends of the second solenoid valve (14) and the fourth solenoid valve (24) are connected by a sealed pipe. The output ends of the first mass flow controller (15) and the second mass flow controller (25) are connected by a sealed pipe. The pipe between the output ends of the second solenoid valve (14) and the fourth solenoid valve (24) is connected to the pipe between the output ends of the first mass flow controller (15) and the second mass flow controller (25), and is sealed to the input end of the buffer tank (30). The output end of the buffer tank (30) is sealed to the input end of the second compressor (60) through a pipe. The output end of the second compressor (60) is sealed to the input end of the sixth solenoid valve (61) through a pipe. The output end of the sixth solenoid valve (61) is sealed to the air inlet (63) through a pipe. The second pressure sensor (62) is sealed and installed on the pipe at the output end of the sixth solenoid valve (61). The input end of the proportional valve (51) is sealed to the output end of the buffer tank (30) through a pipe, the output end of the proportional valve (51) is sealed to the input end of the mixing ratio detection device (50) through a pipe, and the output end of the mixing ratio detection device (50) is sealed to the input end of the second compressor (60) through a pipe. The input end of the fifth solenoid valve (41) is sealed and connected to the pipeline between the output end of the buffer tank (30) and the input end of the second compressor (60) through a pipe. The output end of the fifth solenoid valve (41) is sealed and connected to the input end of the vacuum pump (40) through a pipe. The vacuum gauge (42) is sealed and installed on the pipeline between the output end of the fifth solenoid valve (41) and the input end of the vacuum pump (40).

[0026] II. Calibration of Reference Pressure Value of Mixed Insulating Gas in Buffer Tank The experimental conditions were as follows: the temperature was 20℃, the value Q1 of the first mass flow controller (15) was set to 30L / min, the value Q2 of the second mass flow controller (25) was set to 70L / min, and the inflation time of both the first and second air passages was set to 30s. The four inflation conditions were as follows: 2.1 When the gas introduced into the first gas path is SF6 and the gas introduced into the second gas path is N2, the specific details are as follows: The first cylinder (10) is an SF6 cylinder. Open the first pressure reducing valve (11) to reduce the pressure of SF6 in the first cylinder (10) to 0.6MPa. Turn on the first heat exchanger (12) to heat the SF6 to 20℃. Set the value Q1 of the first mass flow controller (15) to 30L / min and the filling time to 30s. Open the first solenoid valve (13) to fill the buffer tank (30) with SF6. The second cylinder (20) is an N2 gas cylinder. Open the second pressure reducing valve (21) to reduce the pressure of N2 in the second cylinder (20) to 0.6MPa, turn on the second heat exchanger (22) to heat N2 to 20℃, set the value Q2 of the second mass flow controller (25) to 70L / min, the filling time is 30s, and open the third solenoid valve (23) to fill N2 into the buffer tank (30); Turn on the first compressor (31) to draw the gas inside the buffer tank (30) from the bottom of the buffer tank (30) to the top of the buffer tank (30) for circulation and uniform mixing. At this time, the first temperature sensor (32) monitors the temperature of the buffer tank (30) as 20°C and the first pressure sensor (33) monitors the pressure of the buffer tank (30) as P1=0.5000MPa.

[0027] 2.2 When the gas introduced into the first gas path is N2 and the gas introduced into the second gas path is SF6, the specific details are as follows: The first cylinder (10) is an N2 gas cylinder. Open the first pressure reducing valve (11) to reduce the pressure of N2 in the first cylinder (10) to 0.6MPa. Turn on the first heat exchanger (12) to heat N2 to 20℃. Set the value Q1 of the first mass flow controller (15) to 30L / min and the filling time to 30s. Open the first solenoid valve (13) to fill N2 into the buffer tank (30). The second cylinder (20) is an SF6 cylinder. Open the second pressure reducing valve (21) to reduce the pressure of SF6 in the second cylinder (20) to 0.6MPa. Turn on the second heat exchanger (22) to heat the SF6 to 20℃. Set the value Q2 of the second mass flow controller (25) to 70L / min and the filling time to 30s. Open the third solenoid valve (23) to fill the buffer tank (30) with SF6. Turn on the first compressor (31) to draw the gas inside the buffer tank (30) from the bottom of the buffer tank (30) to the top of the buffer tank (30) for circulation and uniform mixing. At this time, the first temperature sensor (32) monitors the temperature of the buffer tank (30) as 20°C and the first pressure sensor (33) monitors the pressure of the buffer tank (30) as P2=0.6615MPa.

[0028] 2.3 When the gas introduced into the first gas path is C4F7N and the gas introduced into the second gas path is CO2, the specific details are as follows: The first cylinder (10) is a C4F7N gas cylinder. Open the first pressure reducing valve (11) to reduce the pressure of C4F7N in the first cylinder (10) to 0.6MPa. Turn on the first heat exchanger (12) to heat C4F7N to 20℃. Set the value Q1 of the first mass flow controller (15) to 30L / min and the filling time to 30s. Open the first solenoid valve (13) to fill C4F7N into the buffer tank (30). The second cylinder (20) is a CO2 cylinder. Open the second pressure reducing valve (21) to reduce the pressure of CO2 in the second cylinder (20) to 0.6MPa, turn on the second heat exchanger (22) to heat CO2 to 20℃, set the value Q2 of the second mass flow controller (25) to 70L / min, the filling time is 30s, and open the third solenoid valve (23) to fill CO2 into the buffer tank (30); Turn on the first compressor (31) to draw the gas inside the buffer tank (30) from the bottom of the buffer tank (30) to the top of the buffer tank (30) for circulation and uniform mixing. At this time, the first temperature sensor (32) monitors the temperature of the buffer tank (30) as 20°C and the first pressure sensor (33) monitors the pressure of the buffer tank (30) as 0.9941 MPa.

[0029] 2.4 When the gas introduced into the first gas path is CO2 and the gas introduced into the second gas path is C4F7N, the specific details are as follows: The first cylinder (10) is a CO2 cylinder. Open the first pressure reducing valve (11) to reduce the CO2 pressure in the first cylinder (10) to 0.6MPa, turn on the first heat exchanger (12) to heat the CO2 to 20℃, set the value Q1 of the first mass flow controller (15) to 30L / min, the filling time is 30s, and open the first solenoid valve (13) to fill the CO2 into the buffer tank (30). The second cylinder (20) is a C4F7N gas cylinder. Open the second pressure reducing valve (21) to reduce the pressure of C4F7N in the second cylinder (20) to 0.6MPa. Turn on the second heat exchanger (22) to heat C4F7N to 20℃. Set the value Q2 of the second mass flow controller (25) to 70L / min and the filling time to 30s. Open the third solenoid valve (23) to fill C4F7N into the buffer tank (30). Turn on the first compressor (31) to draw the gas inside the buffer tank (30) from the bottom of the buffer tank (30) to the top of the buffer tank (30) for circulation and uniform mixing. At this time, the first temperature sensor (32) monitors the temperature of the buffer tank (30) as 20°C and the first pressure sensor (33) monitors the pressure of the buffer tank (30) as 1.1870MPa.

[0030] The test calibration of the pressure value of the mixed insulating gas in the buffer tank (30) under the above four inflation conditions (temperature is 20℃) is shown in the table below.

[0031]

[0032] As can be seen from the table above, the pressure of the buffer tank (30) is different under the above-mentioned inflation conditions, and the difference is quite obvious. Therefore, the inflation condition of the device can be determined by detecting the pressure of the mixed insulating gas in the buffer tank (30).

[0033] 3. Fill the gas chamber of electrical equipment with SF6 / N2 mixed insulating gas. The specific steps for charging and replenishing the device are as follows: 3.1 Vacuuming of the apparatus Initially, the first mass flow controller (15) outputs SF6 by default, and the second mass flow controller (25) outputs N2 by default. The proportional coefficients of the mass flow controllers are set to the proportional coefficients of SF6 and N2 by default, respectively. Open the first solenoid valve (13), the second solenoid valve (14), the third solenoid valve (23), the fourth solenoid valve (24), and the fifth solenoid valve (41), and start the vacuum pump (40) to evacuate the entire device to 133Pa. At this time, turn off the vacuum pump (40), and after the device stands for 30 minutes, read the vacuum value X of the vacuum gauge (42). After standing for another 5 hours, read the vacuum value Y of the vacuum gauge (42). The rise value (YX) should not exceed 67Pa, and the vacuum evacuation is considered to be qualified. After the vacuum evacuation is completed, close the first solenoid valve (13), the second solenoid valve (14), the third solenoid valve (23), the fourth solenoid valve (24), and the fifth solenoid valve (41).

[0034] 3.2 Identify the type of gas used for filling. Adjust the first pressure reducing valve (11) and the second pressure reducing valve (21) to 0.6 MPa. Set the value Q1 of the first mass flow controller (15) to 30 L / min and the inflation time to 30 s. Set the value Q2 of the second mass flow controller (25) to 70 L / min and the inflation time to 30 s. Open the first solenoid valve (13) and the third solenoid valve (23). SF6 and N2 inflation gases enter the buffer tank (30) and are mixed by the first compressor (31). Record the pressure P in the buffer tank (30) at this time. a1 and temperature .

[0035] P a1 When converted to isodense, the pressure P at 20°C b1 The specific calculation process is as follows: According to Dalton's law of partial pressures, the partial pressures of SF6 and N2 are respectively: (1) In the formula, For SF6 gas partial pressure, The percentage of SF6 gas. The partial pressure of N2 gas, This represents the percentage of N2 gas.

[0036] Will and temperature Substituting the values ​​into the Beattie-Bridgeman equation of state, calculate the SF6 gas density at this temperature and pressure. as follows: (2) In the formula, For gas density, Kelvin temperature .

[0037] Due to the temperature of 20℃ and The SF6 gas in the buffer tank (30) has the same density, therefore the temperature is 20℃, i.e., T1 = 20 + 273.15 and Substituting back into equation (2), we can obtain the density as The partial pressure of SF6 gas at a temperature of 20℃, i.e., T1 = 20 + 273.15. .

[0038] Will Substituting into the ideal gas law, calculate the partial pressure of N2 gas at 20℃: (3) In the formula, This represents the pressure value of N2 gas at 20°C under isodense conditions. , =293.15K.

[0039] Transformed and The sum is the pressure P of the SF6 / N2 mixed insulating gas at 20℃. b1 .

[0040] 3.3 Determining the inflation status Compare the pressure P of the mixed insulating gas at 20℃ b1 Calibration value of mixed insulating gas pressure test: If P b1 The closest to P1 is the inflation configuration: the first gas path is filled with SF6, and the second gas path is filled with N2; if P b1 The closest to P2 is filled with N2 gas in the first gas path and SF6 gas in the second gas path.

[0041] 3.4 Preparation and Compensation of Mixed Insulating Gases This embodiment uses the preparation of a mixed insulating gas with SF6:N2 = 30%:70% as an example for illustration.

[0042] When the gas in the first gas path is SF6 and the gas in the second gas path is N2, the first gas cylinder (10) and the second gas cylinder (20) are not reversed. At this time, SF6:N2=30%:70% meets the mixing ratio requirement. No gas compensation is required. SF6 and N2 can be added to the buffer tank (30) to prepare a mixed insulating gas.

[0043] When the gas supplied through the first gas line is N2 and the gas supplied through the second gas line is SF6, and the first cylinder (10) and the second cylinder (20) are connected in reverse, the preparation of the mixed insulating gas should be stopped, and the amount of gas to be compensated should be [not specified]. for: (4) In the formula, This refers to the amount of SF6 gas. This refers to the amount of N2 gas. The proportional coefficient for the SF6 mass flow controller. The inflation time is 30 seconds. After gas compensation, the value Q1 of the first mass flow controller (15) is set to 70L / min, and the value Q2 of the second mass flow controller (25) is set to 30L / min. SF6 and N2 are then added to the buffer tank (30) to prepare a mixed insulating gas.

[0044] 3.5. Mixing ratio detection and inflation. After the mixed insulating gas is prepared, the proportional valve (51) is opened. After the mixing ratio detection device (50) detects that the mixing ratio of the prepared mixed insulating gas meets the requirements, the sixth solenoid valve (61) is opened and the second compressor (60) is started to charge the gas chamber of the electrical equipment. After the second pressure sensor (62) detects that the charging pressure reaches the rated pressure of the gas chamber, the charging stops.

[0045] IV. Fill the gas chamber of electrical equipment with a C4F7N / CO2 mixed insulating gas. The specific steps for charging and replenishing the device are as follows: 4.1 Vacuuming of the apparatus Open the first solenoid valve (13), the second solenoid valve (14), the third solenoid valve (23), the fourth solenoid valve (24), and the fifth solenoid valve (41), and start the vacuum pump (40) to evacuate the entire device to 133 Pa. At this time, turn off the vacuum pump (40), and after the device has been left to stand for 30 minutes, read the vacuum value X of the vacuum gauge (42). After standing for another 5 hours, read the vacuum value Y of the vacuum gauge (42). The increase value (YX) should not exceed 67 Pa, and the vacuum evacuation is considered to be qualified. After the vacuum evacuation is completed, close the first solenoid valve (13), the second solenoid valve (14), the third solenoid valve (23), the fourth solenoid valve (24), and the fifth solenoid valve (41).

[0046] 4.2 Identify the type of gas used for filling. Adjust the first pressure reducing valve (11) and the second pressure reducing valve (21) to 0.6 MPa. Set the value Q1 of the first mass flow controller (15) to 30 L / min and the inflation time to 30 s. Set the value Q2 of the second mass flow controller (25) to 70 L / min and the inflation time to 30 s. Open the first solenoid valve (13) and the third solenoid valve (23). The two inflation gases enter the buffer tank and are mixed by the first compressor (31). Record the pressure P in the buffer tank (30) at this time. a2 and temperature .

[0047] P a2 The pressure P at 20°C when converted to equimolar volume b2 The specific calculation process is as follows: According to Dalton's law of partial pressures, the partial pressures of C4F7N and CO2 are respectively: (5) In the formula, For C4F7N gas partial pressure, The proportion of C4F7N gas. For CO2 gas partial pressure, This represents the percentage of CO2 gas.

[0048] Will and temperature Substitute the values ​​into the Peng-Robinson equation to calculate the molar volume of C4F7N gas at this temperature and pressure. as follows: (6) In the formula, This represents the gas pressure of C4F7N at 20℃. The gas constant is... Kelvin temperature , The molar volume of C4F7N , , These are the correction parameters for the gas in the Peng-Robinson equation. The critical temperature is 385.928 K. For temperature comparison, The critical pressure is set at 2.5028 MPa. The eccentricity factor is 0.47340.

[0049] Because the temperature is 20℃ and the temperature is The molar volumes of C4F7N gas in the buffer tank (30) are the same, therefore the temperature is 20℃, i.e., T2 = 20 + 273.15 and Substituting back into equation (4), we can obtain the molar volume as follows: The partial pressure of C4F7N gas at a temperature of 20℃, i.e., T1 = 20 + 273.15. .

[0050] Will Substituting into the ideal gas law, calculate the partial pressure of CO2 gas at 20℃: (7) In the formula, This represents the CO2 gas pressure at 20°C under isodensity conditions. , =293.15K.

[0051] Transformed and The sum is the pressure P of the C4F7N / CO2 mixed insulating gas at 20℃. b2 .

[0052] 4.3 Determining the inflation status Compare the pressure P of the mixed insulating gas at 20℃ b2 Calibration value of mixed insulating gas pressure test: If P b2 The closest to P3 is the inflation configuration: the first gas path is filled with C4F7N, and the second gas path is filled with CO2; if P b2 The closest to P4 is filled with CO2 in the first gas path and C4F7N in the second gas path.

[0053] 4.4 Preparation and Compensation of Mixed Insulating Gases The following explanation uses the preparation of a mixed insulating gas with a C4F7N:CO2 ratio of 15%:85% as an example.

[0054] When C4F7N is introduced into the first gas line and CO2 is introduced into the second gas line, and the first gas cylinder (10) and the second gas cylinder (20) are not connected in reverse, the amount of gas to be compensated is... for: (8) When CO2 is introduced into the first gas line and C4F7N is introduced into the second gas line, and the first gas cylinder (10) and the second gas cylinder (20) are connected in reverse, the amount of gas to be compensated is... for: (9) In the formula, The gas volume of C4F7N is [missing information]. This refers to the volume of CO2 gas. The proportional gain for the C4F7N mass flow controller. This is the proportional coefficient for the CO2 mass flow controller.

[0055] After gas compensation, the value Q1 of the first mass flow controller (15) is set to 15L / min, and the value Q2 of the second mass flow controller (25) is set to 85L / min. Then, C4F7N and CO2 are continuously added to the buffer tank (30) to prepare a mixed insulating gas.

[0056] 4.5. Mixing ratio detection and inflation. After the mixed insulating gas is prepared, the proportional valve (51) is opened. After the mixing ratio detection device (50) detects that the mixing ratio of the prepared mixed insulating gas meets the requirements, the sixth solenoid valve (61) is opened and the second compressor (60) is started to charge the gas chamber of the electrical equipment. After the second pressure sensor (62) detects that the charging pressure reaches the rated pressure of the gas chamber, the charging stops.

[0057] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A mixed insulating gas replenishment device, characterized in that, include: The system comprises a first gas path, a second gas path, a mixing device, a vacuuming device, a mixing ratio detection unit, and a gas replenishment unit; the first gas path includes: a first gas cylinder (10), a first pressure reducing valve (11), a first heat exchanger (12), a first solenoid valve (13), a second solenoid valve (14), and a first mass flow controller (15); the second gas path includes: a second gas cylinder (20), a second pressure reducing valve (21), a second heat exchanger (22), a third solenoid valve (23), a fourth solenoid valve (24), and a second mass flow controller (25); the mixing device includes: a buffer tank (30), a first compressor (31), a first temperature sensor (32), and a first pressure sensor (33); the vacuuming device includes: a vacuum pump (40), a fifth solenoid valve (41), and a vacuum gauge (42); the mixing ratio detection unit includes: a mixing ratio detection device (50) and a proportional valve (51); the gas replenishment unit includes: a second compressor (60), a sixth solenoid valve (61), a second pressure sensor (62), and a gas filling port (63); The input end of the first pressure reducing valve (11) is sealed to the first steel cylinder (10) through a pipe, the output end of the first pressure reducing valve (11) is sealed to the input end of the first heat exchanger (12) through a pipe, the output end of the first heat exchanger (12) is sealed to the input end of the first solenoid valve (13) through a pipe, and the output end of the first solenoid valve (13), the input end of the second solenoid valve (14), and the input end of the first mass flow controller (15) are sealed to each other through a three-way pipe. The input end of the second pressure reducing valve (21) is sealed to the second steel cylinder (20) through a pipe, the output end of the second pressure reducing valve (21) is sealed to the input end of the second heat exchanger (22) through a pipe, the output end of the second heat exchanger (22) is sealed to the input end of the third solenoid valve (23) through a pipe, and the output end of the third solenoid valve (23), the input end of the fourth solenoid valve (24), and the input end of the second mass flow controller (25) are sealed to each other through a three-way pipe. The output ends of the second solenoid valve (14) and the fourth solenoid valve (24) are connected by a sealed pipe. The output ends of the first mass flow controller (15) and the second mass flow controller (25) are connected by a sealed pipe. The pipe between the output ends of the second solenoid valve (14) and the fourth solenoid valve (24) is connected to the pipe between the output ends of the first mass flow controller (15) and the second mass flow controller (25), and is sealed to the input end of the buffer tank (30). The output end of the buffer tank (30) is sealed to the input end of the second compressor (60) through a pipe. The output end of the second compressor (60) is sealed to the input end of the sixth solenoid valve (61) through a pipe. The output end of the sixth solenoid valve (61) is sealed to the air inlet (63) through a pipe. The second pressure sensor (62) is sealed and installed on the pipe at the output end of the sixth solenoid valve (61). The input end of the proportional valve (51) is sealed to the output end of the buffer tank (30) through a pipe, the output end of the proportional valve (51) is sealed to the input end of the mixing ratio detection device (50) through a pipe, and the output end of the mixing ratio detection device (50) is sealed to the input end of the second compressor (60) through a pipe. The input end of the fifth solenoid valve (41) is sealed and connected to the pipeline between the output end of the buffer tank (30) and the input end of the second compressor (60) through a pipe. The output end of the fifth solenoid valve (41) is sealed and connected to the input end of the vacuum pump (40) through a pipe. The vacuum gauge (42) is sealed and installed on the pipeline between the output end of the fifth solenoid valve (41) and the input end of the vacuum pump (40).

2. A method for replenishing gas using the mixed insulating gas replenishing device according to claim 1, characterized in that, Includes the following steps: Step 1: Calibration of reference pressure value of mixed insulating gas; Step 2: Evacuate the device; Step 3: Identify the type of gas being filled and determine the inflation status; Step 4: Preparation and compensation of mixed insulating gas; Step 5: Detect the mixing ratio and inflate.

3. The gas filling method according to claim 2, characterized in that, The method for calibrating the reference pressure value of the mixed insulating gas described in step 1 is as follows: (1) The test conditions are set as follows: the temperature is 20℃, the value Q1 of the first mass flow controller (15) is set to 30L / min, the value Q2 of the second mass flow controller (25) is set to 70L / min, and the charging time of the first gas path and the second gas path is set to 30s. (2) When the gas in the first gas path is SF6 and the gas in the second gas path is N2, the pressure of the calibrated buffer tank (30) is P1=0.5000MPa; when the gas in the first gas path is N2 and the gas in the second gas path is SF6, the pressure of the calibrated buffer tank (30) is P2=0.6615MPa; when the gas in the first gas path is C4F7N and the gas in the second gas path is CO2, the pressure of the calibrated buffer tank (30) is P3=0.9941MPa; when the gas in the first gas path is CO2 and the gas in the second gas path is C4F7N, the pressure of the calibrated buffer tank (30) is P4=1.1870MPa.

4. The gas filling method according to claim 3, characterized in that, The method for evacuating the device described in step 2 is as follows: Open the first solenoid valve (13), the second solenoid valve (14), the third solenoid valve (23), the fourth solenoid valve (24), and the fifth solenoid valve (41), start the vacuum pump (40) to evacuate the entire device to 133 Pa, then turn off the vacuum pump (40), let the device stand for 30 minutes and then read the vacuum value X of the vacuum gauge (42), and let it stand for another 5 hours and then read the vacuum value Y of the vacuum gauge (42). The increase value (YX) should not exceed 67 Pa, and the evacuation is considered to be qualified. After the evacuation is completed, close the first solenoid valve (13), the second solenoid valve (14), the third solenoid valve (23), the fourth solenoid valve (24), and the fifth solenoid valve (41).

5. The gas filling method according to claim 4, characterized in that, When filling the gas chamber of electrical equipment with a mixed SF6 / N2 insulating gas, the method for identifying the type of gas being filled and determining the filling status in step 3 is as follows: (1) Adjust the first pressure reducing valve (11) and the second pressure reducing valve (21) to 0.6MPa, set the value Q1 of the first mass flow controller (15) to 30L / min and the inflation time to 30s, set the value Q2 of the second mass flow controller (25) to 70L / min and the inflation time to 30s, open the first solenoid valve (13) and the third solenoid valve (23), and the two inflation gases, SF6 and N2, enter the buffer tank (30) and are mixed by the first compressor (31). Record the pressure P in the buffer tank (30) at this time. a1 and temperature ; (2) P a1 When converted to isodense, the pressure P at 20°C b1 The specific calculation process is as follows: According to Dalton's law of partial pressures, the partial pressures of SF6 and N2 are respectively: （1） In the formula, For SF6 gas partial pressure, The percentage of SF6 gas. The partial pressure of N2 gas, The percentage of N2 gas; Will and temperature Substituting the values ​​into the Beattie-Bridgeman equation of state, calculate the SF6 gas density at this temperature and pressure. as follows: （2） In the formula, For gas density, Kelvin temperature ; Due to the temperature of 20℃ and The SF6 gas in the buffer tank (30) has the same density, therefore the temperature is 20℃, i.e., T1 = 20 + 273.15 and Substituting back into equation (2), we obtain the density as The partial pressure of SF6 gas at a temperature of 20℃, i.e., T1 = 20 + 273.

15. ; Will Substituting into the ideal gas law, calculate the partial pressure of N2 gas at 20℃: （3） In the formula, This represents the pressure value of N2 gas at 20°C under isodense conditions. , =293.15K; Transformed and The sum is the pressure P of the SF6 / N2 mixed insulating gas at 20℃. b1 ; (3) Compare the pressure P of the mixed insulating gas at 20℃ b1 Calibration value of mixed insulating gas pressure test: If P b1 The closest to P1 is the inflation configuration: the first gas path is filled with SF6, and the second gas path is filled with N2; if P b1 The closest to P2 is filled with N2 gas in the first gas path and SF6 gas in the second gas path.

6. The gas filling method according to claim 5, characterized in that, The method for preparing and compensating the mixed insulating gas described in step 4 is as follows: When the gas in the first gas path is SF6 and the gas in the second gas path is N2, the first gas cylinder (10) and the second gas cylinder (20) are not reversed. At this time, SF6:N2=30%:70% meets the mixing ratio requirement. No gas compensation is performed. SF6 and N2 are continued to be added to the buffer tank (30) to prepare a mixed insulating gas. When the gas supplied through the first gas line is N2 and the gas supplied through the second gas line is SF6, the first cylinder (10) and the second cylinder (20) are connected in reverse, the preparation of the mixed insulating gas stops, and the amount of gas to be compensated is [not specified]. for: （4） In the formula, This refers to the amount of SF6 gas. This refers to the amount of N2 gas. The proportional coefficient for the SF6 mass flow controller. The inflation time is 30 seconds. After gas compensation, the value Q1 of the first mass flow controller (15) is set to 70L / min, and the value Q2 of the second mass flow controller (25) is set to 30L / min. SF6 and N2 are then added to the buffer tank (30) to prepare a mixed insulating gas.

7. The gas filling method according to claim 6, characterized in that, The method for detecting the mixing ratio and charging in step 5 is as follows: Open the proportional valve (51), and after the mixing ratio detection device (50) detects that the mixing ratio of the prepared mixed insulating gas meets the requirements, open the sixth solenoid valve (61), start the second compressor (60) to charge the gas chamber of the electrical equipment, and stop charging after the second pressure sensor (62) detects that the charging pressure reaches the rated pressure of the gas chamber.

8. The gas filling method according to claim 4, characterized in that, When filling the gas chamber of electrical equipment with a C4F7N / CO2 mixed insulating gas, the method for identifying the type of gas being filled and determining the filling status in step 3 is as follows: (1) Adjust the first pressure reducing valve (11) and the second pressure reducing valve (21) to 0.6MPa, set the value Q1 of the first mass flow controller (15) to 30L / min and the inflation time to 30s, set the value Q2 of the second mass flow controller (25) to 70L / min and the inflation time to 30s, open the first solenoid valve (13) and the third solenoid valve (23), and the two inflation gases enter the buffer tank and are mixed by the first compressor (31). Record the pressure P in the buffer tank (30) at this time. a2 and temperature ; (2) P a2 The pressure P at 20°C when converted to equimolar volume b2 ; The specific calculation process is as follows: According to Dalton's law of partial pressures, the partial pressures of C4F7N and CO2 are respectively: （5） In the formula, For C4F7N gas partial pressure, The proportion of C4F7N gas. For CO2 gas partial pressure, The percentage of CO2 gas; Will and temperature Substitute the values ​​into the Peng-Robinson equation to calculate the molar volume of C4F7N gas at this temperature and pressure. as follows: （6） In the formula, This represents the gas pressure of C4F7N at 20℃. The gas constant is... Kelvin temperature , The molar volume of C4F7N , , These are the correction parameters for the gas in the Peng-Robinson equation. The critical temperature. For temperature comparison, The critical pressure. It is the eccentricity factor; Because the temperature is 20℃ and the temperature is The molar volumes of C4F7N gas in the buffer tank (30) are the same, therefore the temperature is 20℃, i.e., T2 = 20 + 273.15 and Substituting back into equation (4), we obtain the molar volume as follows: The partial pressure of C4F7N gas at a temperature of 20℃, i.e., T1 = 20 + 273.

15. ; Will Substituting into the ideal gas law, calculate the partial pressure of CO2 gas at 20℃: （7） In the formula, This represents the CO2 gas pressure at 20°C under isodensity conditions. , =293.15K; Transformed and The sum is the pressure P of the C4F7N / CO2 mixed insulating gas at 20℃. b2 ; (3) Compare the pressure P of the mixed insulating gas at 20℃ b2 Calibration value of mixed insulating gas pressure test: If P b2 The closest to P3 is the inflation configuration: the first gas path is filled with C4F7N, and the second gas path is filled with CO2; if P b2 The closest to P4 is filled with CO2 in the first gas path and C4F7N in the second gas path.

9. The gas filling method according to claim 8, characterized in that, The method for preparing and compensating the mixed insulating gas described in step 4 is as follows: When C4F7N is introduced into the first gas line and CO2 is introduced into the second gas line, and the first gas cylinder (10) and the second gas cylinder (20) are not connected in reverse, the amount of gas to be compensated is... for: （8） When CO2 is introduced into the first gas line and C4F7N is introduced into the second gas line, and the first gas cylinder (10) and the second gas cylinder (20) are connected in reverse, the amount of gas to be compensated is... for: （9） In the formula, The gas volume of C4F7N is [missing information]. This refers to the volume of CO2 gas. The proportional gain for the C4F7N mass flow controller. This is the proportional coefficient for the CO2 mass flow controller; After gas compensation, the value Q1 of the first mass flow controller (15) is set to 15L / min, and the value Q2 of the second mass flow controller (25) is set to 85L / min. Then, C4F7N and CO2 are continuously added to the buffer tank (30) to prepare a mixed insulating gas.

10. The gas filling method according to claim 9, characterized in that, The method for detecting the mixing ratio and charging in step 5 is as follows: Open the proportional valve (51), and after the mixing ratio detection device (50) detects that the mixing ratio of the prepared mixed insulating gas meets the requirements, open the sixth solenoid valve (61), start the second compressor (60) to charge the gas chamber of the electrical equipment, and stop charging after the second pressure sensor (62) detects that the charging pressure reaches the rated pressure of the gas chamber.

Images