Vacuum C 4 F 7 N / CO 2 / O 2 Mixed gas leakage characteristic detection system and method

Abstract

The present invention relates to a detection system and method for the leakage characteristics of a C4F7N / CO2 / O2 mixed gas in a vacuum. After using a vacuum pumping device to obtain an initial vacuum environment and the mixed gas, the helium gas supply device and the vacuum pumping device are alternately used to alternately introduce helium gas at different preset pressures and pump the vacuum to form a new vacuum environment. The mixed gas is introduced into the new vacuum environment, and a helium ionization gas chromatograph is used to detect the first O2 leakage concentration corresponding to the initial vacuum environment and the second O2 leakage concentration corresponding to the new vacuum environment, so as to obtain the true leakage concentrations of O2, C4F7N, and CO2 in the vacuum. Compared with the prior art, the present invention has the advantages of effectively and accurately detecting the leakage characteristics of the C4F7N / CO2 / O2 ternary mixed gas in the vacuum, etc.

Description

Technical Field

[0001] The present invention relates to the technical field of electrical equipment detection, in particular to a vacuum C 4 F 7 N / CO 2 / O 2 A system and method for detecting leakage characteristics of mixed gases. Background Art

[0002] Since SF6 has a strong greenhouse effect, in order to achieve the goal of "carbon peak and carbon neutrality", researching new environmentally friendly insulating gases to replace pure SF6 gas is an important task in the current power industry. 4 F 7 N / CO 2 / O 2 The environmentally friendly GIS equipment with ternary mixed insulating gas has been initially demonstrated and applied, and the operation effect is good. However, as the operation time of GIS equipment increases, gas leakage is very likely to occur due to equipment aging and other problems, which may cause the pressure of insulating gas in the equipment to decrease, affecting the insulation and arc extinguishing ability of the gas, bringing serious safety hazards to the operation of the equipment and shortening the service life of the equipment.

[0003] The State Grid requires that the annual leakage rate of electrical equipment should not exceed 0.5%. Therefore, daily leakage detection of electrical equipment is of great significance to ensure the safe and stable operation of electrical equipment. The existing technology generally refers to the leakage detection method specified in the standard GB / T11023-2018. Since the air contains 21% O 2 The existing detection instruments cannot measure the leaked trace amount of O 2 (about μL / L level), so C is usually measured by detection instruments. 4 F 7 N and CO 2 The concentration of O 2 Leakage rate.

[0004] However, due to the presence of O 2 The concentration is relatively high (about 21%), and the leaked trace amount of O cannot be measured by the above method. 2 (approximately μL / L), C is calculated only according to the mixing ratio 4 F 7 N / CO 2 / O 2 The leakage rate of the ternary mixed gas will have a large deviation. The gas leakage rate is affected by factors such as gas molecule size and pressure difference. 4 F 7 N / CO 2 / O 2 The leakage of ternary mixed gas in the environment needs to be tested in vacuum.4 F 7 N / CO 2 / O 2 The leakage test of ternary mixed gas is carried out to eliminate the interference of other factors that affect the gas leakage rate.

[0005] However, the development of vacuum C 4 F 7 N / CO 2 / O 2 The difficulty of the ternary mixed gas leakage test is that there is almost no pressure in a vacuum, and the gas leaking into the vacuum cannot be extracted for detection, so the gas leakage rate in the vacuum cannot be obtained. 4 F 7 N / CO 2 / O 2 The test method for the leakage concentration of ternary mixed gas hinders the 4 F 7 N / CO 2 / O 2 Research on the leakage characteristics of ternary mixed gas. Therefore, how to effectively and accurately detect C 4 F 7 N / CO 2 / O 2 The leakage characteristics of the ternary mixed gas are C 4 F 7 N / CO 2 / O 2 Providing strong support for the leak detection and maintenance of ternary mixed gas electrical equipment has become a problem that needs to be solved in this field. Summary of the invention

[0006] The purpose of the present invention is to overcome the vacuum C 4 F 7 N / CO 2 / O 2 The leakage concentration of ternary mixed gas is difficult to accurately detect, so a vacuum C 4 F 7 N / CO 2 / O 2 Mixed gas leakage characteristic detection system and method, established to detect C in vacuum 4 F 7 N / CO 2 / O 2 Ternary mixed gas leakage characteristics test method, carry out C 4 F 7 N / CO 2 / O 2 Ternary mixed gas simulation leakage test, R&D and detection of C in vacuum4 F 7 N / CO 2 / O 2 The test device for the leakage characteristics of ternary mixed gas is used for C 4 F 7 N / CO 2 / O 2 Study on the leakage characteristics of ternary mixed gas and C 4 F 7 N / CO 2 / O 2 Provide technical support for the operation and maintenance of ternary mixed gas GIS equipment.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] According to a first aspect of the present invention, there is provided a vacuum C 4 F 7 N / CO 2 / O 2 A mixed gas leakage characteristic detection system, the system comprising a mixed gas providing device, a helium providing device, a vacuum device, a leakage simulation device, a sealed tank and a helium ionization gas chromatograph, the gas outlet of the mixed gas providing device is connected to the gas inlet pipeline of the leakage simulation device, the gas outlet of the helium providing device is connected to the sealed tank, the vacuum device is connected to the gas inlet of the leakage simulation device, and is connected between the gas outlet of the helium providing device and the sealed tank, the sealed tank is connected to the helium ionization gas chromatograph, and the leakage simulation device is located inside the sealed tank; after the system uses the vacuum device to obtain an initial vacuum environment and a mixed gas, the system alternately uses the helium providing device and the vacuum device to alternately introduce helium of different preset pressures and vacuumize to form a new vacuum environment, introduces the mixed gas into the new vacuum environment, and uses the helium ionization gas chromatograph to detect a first O corresponding to the initial vacuum environment. 2 The leakage concentration and the second O corresponding to the new vacuum environment 2 Leakage concentration, obtained in vacuum O 2 The actual leakage concentration, C 4 F 7 The actual leakage concentration of N and CO 2 The actual leakage concentration.

[0009] As a preferred technical solution, the process of using the system to detect the leakage characteristics of the mixed gas in a vacuum specifically includes: using the vacuum pumping device to pump the space between the outer wall of the leakage simulation device and the inner wall of the sealed tank into an initial vacuum environment, and then using the helium supply device to fill the sealed tank with helium at a second preset pressure, and then re-evacuating to a preset pressure; using the mixed gas supply device to obtain and store the mixed gas; after a preset time, using the helium supply device to fill the sealed tank with helium at a first preset pressure, and after standing, using the helium ionization gas chromatograph to detect the first O 2 Leakage concentration; after evacuating to a preset pressure using the vacuum pumping device, filling the sealed tank with helium of a second preset pressure using the helium providing device; evacuating to the same preset pressure using the vacuum pumping device again to form the new vacuum environment; passing the stored mixed gas into the leakage simulation device; after standing still, filling the sealed tank with helium of the first preset pressure using the helium providing device again, and after standing still again, using the helium ionization gas chromatograph to detect the second O 2 Leakage concentration, vacuum C 4 F 7 The actual leakage concentration of N and CO 2 The actual leakage concentration; According to the first O 2 Leakage concentration and the second O 2 Leakage concentration, obtain vacuum O 2 The actual leakage concentration.

[0010] As a preferred technical solution, the vacuum O 2 The calculation formula for the actual leakage concentration is:

[0011] C O2 =C O2,2 -C O2,1

[0012] In the formula, C O2 Indicates O in vacuum 2 The actual leakage concentration, C O2,1 Indicates the first O 2 Leakage concentration, C o2,2 Indicates the second O 2 Leakage concentration.

[0013] As a preferred technical solution, the C 4 F 7 N / CO 2 / O 2 The ratio of the leakage rate of each component in the mixed gas is:

[0014] F C4F7N : F cO2 : Fo2 =C C4F7N :C CO2 :C O2

[0015] In the formula, F C4F7N 、F CO2 、F O2 Represents C in vacuum 4 F 7 N, CO 2 , O 2 Leakage rate, C C4F7N , C CO2 Represents C in vacuum 4 F 7 N, CO 2 The actual leakage concentration.

[0016] As a preferred technical solution, the system also includes multiple needle valves, through which the mixed gas providing device and the leakage simulation device, the helium providing device and the sealed tank, the vacuum pumping device and the leakage simulation device, the vacuum pumping device and the helium providing device, and the sealed tank and the helium ionization gas chromatograph are all connected.

[0017] As a preferred technical solution, the system further includes a plurality of pressure sensors, and the pressure sensors are connected to the connecting pipe between the mixed gas providing device and the leakage simulation device and to the connecting pipe between the sealing tank and the helium ionization gas chromatograph.

[0018] As a preferred technical solution, the mixed gas providing device includes a gas distributor, a buffer tank, a compressor, a first needle valve and a gas storage tank connected in sequence, and the gas outlet of the gas storage tank is connected to the gas inlet of the leakage simulation device through a second needle valve.

[0019] As a preferred technical solution, the vacuum pumping device includes a vacuum pump and a third needle valve connected in sequence, and a vacuum gauge connected to the other end of the third needle valve. The other end of the third needle valve is also connected to the air inlet pipe of the leakage simulation device, and is also connected between the air outlet of the helium providing device and the sealing tank.

[0020] As a preferred technical solution, the helium supply device includes a helium filling port and a fourth needle valve connected in sequence, and the other end of the fourth needle valve is connected to the sealing tank.

[0021] According to a second aspect of the present invention, there is provided a vacuum C 4 F 7 N / CO 2 / O 2A mixed gas leakage characteristic detection method, the method is implemented by the system, after obtaining an initial vacuum environment and a mixed gas, the method alternately introduces helium with different preset pressures and evacuates the air to form a new vacuum environment, introduces the mixed gas into the new vacuum environment, and detects the first O corresponding to the initial vacuum environment. 2 The leakage concentration and the second O corresponding to the new vacuum environment 2 Leakage concentration, obtained in vacuum O 2 The actual leakage concentration, C 4 F 7 The actual leakage concentration of N and CO 2 The actual leakage concentration.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. C provided by the present invention 4 F 7 N / CO 2 / O 2 The mixed gas leakage characteristic detection system creates a vacuum environment outside the leakage simulation device, alternately uses the helium supply device and the vacuum device to alternately introduce helium with different preset pressures and vacuumize, mixes the trace gas leaked into the vacuum with the filled helium, and provides the intake pressure required for gas chromatograph detection, which can accurately detect the concentration of gas leaked into the vacuum, realizing C in vacuum 4 F 7 N / CO 2 / O 2 Detection of leakage concentration of ternary mixed gas;

[0024] 2. The device provided by the present invention can be used for C 4 F 7 N / CO 2 / O 2 The research on the leakage characteristics of ternary mixed gas provides theoretical and technical support for ensuring C 4 F 7 N / CO 2 / O 2 The safe and stable operation of ternary mixed gas electrical equipment is of great significance;

[0025] 3. The method provided by the present invention is simple to operate and easy to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of the system structure provided in Example 1 of the present invention;

[0027] Figure 2 This is a schematic structural diagram of a mixed gas providing device in Example 1 of the present invention;

[0028] Figure 3 This is a schematic diagram of the structure of the vacuum pumping device in Example 1 of the present invention;

[0029] Figure 4 This is a schematic diagram of the structure and connection of a helium supply device, a leakage simulation device, a sealed tank and a helium ionization gas chromatograph in Example 1 of the present invention;

[0030] Among them: 1. gas distribution instrument; 2. buffer tank; 3. compressor; 4. first needle valve; 5. gas storage tank; 6. second needle valve; 7. first pressure sensor; 8. vacuum pump; 9. third needle valve; 10. helium filling port; 11. fourth needle valve; 12. fifth needle valve; 13. vacuum gauge; 14. sixth needle valve; 15. sealed tank body; 16. leakage simulation device; 17. second pressure sensor; 18. seventh needle valve; 19. helium ionization gas chromatograph. DETAILED DESCRIPTION

[0031] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0032] Example 1

[0033] like Figure 1 As shown, this embodiment provides a vacuum C 4 F 7 N / CO 2 / O 2 Mixed gas leakage characteristic detection system. The system specifically includes a gas distributor 1, a buffer tank 2, a compressor 3, a first needle valve 4, a gas storage tank 5, a second needle valve 6, a first pressure sensor 7, a vacuum pump 8, a third needle valve 9, a helium filling port 10, a fourth needle valve 11, a fifth needle valve 12, a vacuum gauge 13, a sixth needle valve 14, a sealed tank body 15, a leakage simulation device 16, a second pressure sensor 17, a seventh needle valve 18 and a helium ionization gas chromatograph 19.

[0034] The leakage simulation device 16 is located inside the sealed tank 15 .

[0035] like Figure 2 As shown, the mixed gas providing device includes a gas distributor 1, a buffer tank 2, a compressor 3, a first needle valve 4 and a gas storage tank 5 connected in sequence. The gas outlet of the gas storage tank 5 is connected to the gas inlet pipeline of the leakage simulation device 16 through the second needle valve 6, and the first pressure sensor 7 is connected to the pipeline.

[0036] like Figure 3As shown, the vacuum pumping device includes a vacuum pump 8 and a third needle valve 9 connected in sequence, and a vacuum gauge 13 connected to the other end of the third needle valve 9. The other end of the third needle valve 9 is also connected to the air inlet pipe of the leakage simulation device 16 through the sixth needle valve 14, and the other end of the third needle valve 9 is also connected between the fourth needle valve 11 and the sealed tank body 15 through the fifth needle valve 12.

[0037] like Figure 4 As shown, the helium supply device includes a helium filling port 10 and a fourth needle valve 11 connected in sequence. The other end of the fourth needle valve 11 is connected to a pipeline of a sealed tank body 15. The sealed tank body 15 is connected to a helium ionization gas chromatograph 19 through a seventh needle valve 18, and a second pressure sensor 17 is connected to the pipeline.

[0038] The above system is used to detect C in vacuum 4 F 7 N / CO 2 / O 2 The process of mixed gas leakage characteristics specifically includes:

[0039] First, the space between the outer wall of the leakage simulation device 16 and the inner wall of the sealed tank body 15 is evacuated to an initial vacuum environment by using a vacuum pump, and then 0.05MPa of high-purity helium is filled into the space through the helium filling port 10, and then the space is evacuated to 67Pa; secondly, the mixed gas is obtained by using the gas distributor 1 in the mixed gas providing device, and the mixed gas is stored in the gas storage tank 5; after a period of time (at least 24 hours), 0.3MPa of pure helium is filled into the sealed tank body 15 by using the helium providing device, and after standing, the first O is detected by using the helium ionization gas chromatograph 19. 2 Leakage concentration; again, after evacuating to 67Pa using the vacuum device, 0.05MPa of pure helium is filled into the sealed tank body 15 using the helium supply device; then, after evacuating to 67Pa using the vacuum device again, a new vacuum environment is formed; the stored mixed gas is passed into the leakage simulation device 16; after standing for at least 24h, 0.3MPa of helium is filled into the sealed tank body 15 again using the helium supply device, and after standing again, the second O is detected using the helium ionization gas chromatograph 19 2 Leakage concentration, vacuum C 4 F 7 The actual leakage concentration of N and CO 2 The actual leakage concentration; according to the first O 2 Leakage concentration and second O 2 The difference in leakage concentration is used to obtain the O 2 The actual leakage concentration.

[0040] Example 2

[0041] This embodiment provides a vacuum C 4 F7 N / CO 2 / O 2 The mixed gas leakage characteristic detection test method is implemented using the detection device provided in Example 1. The device structure is the same as that in Example 1 and will not be described in detail here. The test process is as follows:

[0042] Build as Figure 1 The vacuum C 4 F 7 N / CO 2 / O 2 The test device for the leakage characteristics of the ternary mixed gas is connected to the gas distribution device 1, the buffer tank 2 and the compressor 3, and controlled by the first needle valve 4; the air inlet of the leakage simulation device 16 is connected to the gas inlet of ... 4 F 7 N / CO 2 / O 2 The gas storage tank 5 of the ternary mixed gas is connected through a pipeline, and is controlled by the second needle valve 6 in the middle; the sealed tank body 15 is connected to the helium filling port 10 and is controlled by the fourth needle valve 11, and the vacuum pump 8 and the vacuum gauge 13 are simultaneously connected to the leakage simulation device 16 and the sealed tank body 15, and the passage is controlled by the third needle valve 9, the fifth needle valve 12 and the sixth needle valve 14; the sealed tank body 15 is connected to the second pressure sensor 17 and the seventh needle valve 18, and the gas is controlled by the seventh needle valve 18 to enter the helium ionization gas chromatograph 19 for detection. The specific working principle and test method are as follows:

[0043] (1) Open the first needle valve 4, the second needle valve 6, the third needle valve 9, the fourth needle valve 11, the fifth needle valve 12, and the sixth needle valve 14, start the vacuum pump 8, and evacuate the buffer tank 2, the gas storage tank 5, the sealed tank body 15, the leakage simulation device 16, and the entire pipeline. When the pressure on the vacuum gauge 13 shows 67Pa, stop evacuating. After 3 hours of stopping evacuating, observe the pressure rise. If the rise value is lower than 67Pa, it means that the airtightness effect is good. Then, fill in 0.05MPa of high-purity helium through the helium filling port 10, and then evacuate to 67Pa. Otherwise, it is necessary to check the airtightness of the device. The purpose of this step is to eliminate the interference of residual gas in the pipeline and create an external vacuum environment for the leakage simulation device 16;

[0044] (2) Open only the first needle valve 4, start the gas distributor 1, and prepare C 4 F 7 N / CO 2 / O 2 Mixed gas (generally C 4 F 7 N is 0-10%, CO 2 80~90%, O 2The mixed gas enters the buffer tank 2 and is then pressurized by the compressor 3 to (P r +1)MPa(P r The pressure required for the mixed gas test) and enters the gas storage tank 5;

[0045] (3) Due to the pressure difference between the inside and outside of the sealed tank 15 after vacuuming, the O 2 A small amount of O2 will enter the sealed tank body 15 under vacuum conditions. After the device is left to stand for 24 hours, 0.3MPa high-purity helium (the helium concentration in the test is 99.999%, close to 100%, and the second pressure sensor 17 is used to observe the inflation pressure) is filled into the sealed tank body 15 from the helium filling port 10. After standing for half an hour, the seventh needle valve 18 is opened, and the helium ionization gas chromatograph 19 is used for detection. The O2 entering the sealed tank body 15 under vacuum conditions is measured. 2 The content is C O2,1 (i.e. the first O 2 Leakage concentration);

[0046] (4) Open the third needle valve 9 and the fifth needle valve 12, start the vacuum pump 8, evacuate the sealed tank body 15 to 67Pa, then stop evacuating and close the third needle valve 9, the fifth needle valve 12 and the vacuum pump 8; open the fourth needle valve 11, inject 0.05MPa of high-purity helium into the sealed tank body 15 through the helium filling port 10 (the helium concentration in the test is 99.999%, close to 100%, and the inflation pressure is observed using the second pressure sensor 17), continue to open the third needle valve 9 and the fifth needle valve 12, start the vacuum pump 8, evacuate the sealed tank body 15 to 67Pa, and then fill it with 0.05MPa of high-purity helium through the helium filling port 10, and then evacuate to 67Pa. The purpose of this step is to eliminate the small amount of residual oxygen in the pipeline, reduce the interference caused by oxygen adsorbed on the pipe wall, and ensure that the outside of the leakage simulation device 16 is in a vacuum environment;

[0047] (5) Open the second needle valve 6, and the mixed gas in the gas tank 5 enters the leakage simulation device 16. When the first pressure sensor 7 shows a pressure of P r When the second needle valve 6 is closed;

[0048] (6) After standing for 24 hours, the mixed gas leaks into the sealed tank body 15 which is already under vacuum conditions through the leakage simulation device 16. At this time, the fourth needle valve 11 is opened, and helium is filled into the sealed tank body 15 under vacuum conditions through the helium filling port 10 to 0.3 MPa (the filling pressure is observed by the second pressure sensor 17). The purpose of this step is to provide the intake pressure required by the helium ion gas chromatograph 19. After standing for half an hour, the seventh needle valve 18 is opened, and the gas to be tested is introduced into the helium ion gas chromatograph 19 for detection, and C is measured. 4 F7 N, CO 2 , O 2 The concentrations of the three components are C C4 , C CO2 , C O2,2 , C O2,2 The second O 2 Leakage concentration. After vacuuming, the sealed tank 15 will enter from the air with a content of C O2,1 O 2 According to the test results, the O in vacuum can be calculated by formula (1). 2 The actual leakage concentration C O2 :

[0049] C O2 =C O2,2 -C O2,1 (1)

[0050] (7) According to formula (2), calculate the vacuum C 4 F 7 N, CO 2 , O 2 The ratio of the leakage rates of the components in the ternary gas mixture:

[0051] F C4F7N : F CO2 : F O2 =C C4F7N :C CO2 :C O2 (2)

[0052] In the formula, F C4F7N 、F CO2 、F O2 The leakage rate (unit: Pa·m 3 / s).

[0053] In summary, this embodiment provides a method suitable for detecting C in vacuum. 4 F 7 N / CO 2 / O 2 The test method and device for the leakage characteristics of ternary mixed gas have the advantages of creating a vacuum environment outside the leakage simulation device, mixing the trace gas leaked into the vacuum with the filled helium, and providing the intake pressure required for gas chromatograph detection, which solves the problem that the existing detection technology cannot detect the concentration of gas leaked into the vacuum, and realizes the C 4 F 7 N / CO 2 / O 2 The device can detect the leakage concentration of ternary mixed gas. 4 F 7 N / CO2 / O 2 The research on the leakage characteristics of ternary mixed gas provides theoretical and technical support for ensuring C 4 F 7 N / CO 2 / O 2 The safe and stable operation of ternary mixed gas electrical equipment is of great significance.

[0054] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A C4F7N / CO2 / O2 mixed gas leakage characteristic detection system in vacuum, characterized in that: The system comprises a mixed gas supply device, a helium supply device, a vacuum device, a leakage simulation device, a sealed tank and a helium ionization gas chromatograph, wherein the gas outlet of the mixed gas supply device is connected to the gas inlet pipeline of the leakage simulation device, the gas outlet of the helium supply device is connected to the sealed tank, the vacuum device is connected to the gas inlet of the leakage simulation device, the sealed tank is connected to the helium ionization gas chromatograph, and the leakage simulation device is located inside the sealed tank; the system also comprises a plurality of needle valves, wherein the mixed gas supply device and the leakage simulation device, the helium supply device and the sealed tank, the vacuum device and the leakage simulation device, the vacuum device and the helium supply device, and the sealed tank and the helium ionization gas chromatograph are connected via the needle valves. valve connection; the system also includes a plurality of pressure sensors, and the pressure sensors are connected to the connecting pipeline between the mixed gas providing device and the leakage simulation device and the connecting pipeline between the sealed tank and the helium ionization gas chromatograph; the mixed gas providing device includes a gas distributor, a buffer tank, a compressor, a first needle valve and a gas storage tank connected in sequence, and the gas outlet of the gas storage tank is connected to the gas inlet of the leakage simulation device through a second needle valve; the vacuum pump includes a vacuum pump and a third needle valve connected in sequence, and a vacuum gauge connected to the other end of the third needle valve, and the other end of the third needle valve is also connected to the gas inlet pipeline of the leakage simulation device; the helium providing device includes a helium filling port and a fourth needle valve connected in sequence, and the fourth needle valve is simultaneously connected between the gas outlet of the helium providing device and the sealed tank; After the system uses the vacuum pumping device to obtain an initial vacuum environment and uses the mixed gas providing device to obtain a mixed gas, the system alternately uses the helium providing device and the vacuum pumping device to alternately introduce helium with different preset pressures and evacuate the air to form a new vacuum environment, introduces the mixed gas into the new vacuum environment, and uses the helium ionization gas chromatograph to detect a first O2 leakage concentration corresponding to the initial vacuum environment and a second O2 leakage concentration corresponding to the new vacuum environment to obtain a true leakage concentration of O2, a true leakage concentration of C4F7N, and a true leakage concentration of CO2 in the vacuum.

2. A method for detecting leakage characteristics of C4F7N / CO2 / O2 mixed gas in vacuum, characterized in that: The method is implemented by using the system according to claim 1, and the process of using the system to detect the leakage characteristics of the mixed gas in a vacuum specifically includes: The vacuuming device is used to evacuate the space between the outer wall of the leakage simulation device and the inner wall of the sealed can into an initial vacuum environment, and then the helium supply device is used to fill the sealed can with helium of a second preset pressure, and then the vacuum is re-evacuated to a preset pressure; Using the mixed gas providing device to obtain and store the mixed gas; After a preset time, the helium supply device is used to fill the sealed tank with helium of a first preset pressure, and after standing, the helium ionization gas chromatograph is used to detect the first O2 leakage concentration; After the vacuuming device is used to evacuate the air to a preset pressure, the helium supply device is used to fill the sealed can with helium at a second preset pressure; After the vacuuming device is used to evacuate the air to the same preset pressure again, a new vacuum environment is formed; Passing the stored mixed gas into the leakage simulation device; After standing still, the helium supply device is used to fill the sealed can with helium of the first preset pressure again, and after standing still again, the helium ionization gas chromatograph is used to detect the second O2 leakage concentration, the real leakage concentration of C4F7N in vacuum, and the real leakage concentration of CO2; According to the first O2 leakage concentration and the second O2 leakage concentration, obtaining a real leakage concentration of O2 in a vacuum; The calculation formula for the actual leakage concentration of O2 in the vacuum is: ， In the formula, Indicates the actual leakage concentration of O2 in vacuum, Indicates the first O2 leakage concentration, Indicates the second O2 leakage concentration; The ratio of the leakage rate of each component in the C4F7N / CO2 / O2 mixed gas in vacuum is: ， In the formula, F C4F7N 、F CO2 、F O2 Respectively represent the leakage rates of C4F7N, CO2, and O2 in vacuum, C C4F7N , C CO2 They represent the actual leakage concentrations of C4F7N and CO2 in vacuum respectively.

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