An environmentally friendly insulating gas for replacing sulfur hexafluoride in situ and its application

Abstract

The invention discloses an environmentally friendly insulating gas that replaces sulfur hexafluoride in situ and its application, and belongs to the technical field of high-voltage or high-current switches with arc extinguishing or arc protection devices. The components of the environmentally friendly insulating gas that replaces sulfur hexafluoride in situ include trifluoromethyl trifluorovinyl ether and a carrier gas; wherein the content of trifluoromethyl trifluorovinyl ether is 70 mol.%-95 mol.%, and the content of the carrier gas is 5 mol.%-30 mol.%; the carrier gas includes at least one of nitrogen, carbon dioxide, and carbon tetrafluoride. The present invention improves the insulation tolerance of the environmentally friendly insulating gas by adjusting the component content, reduces the possibility of generating high-energy arcs, thereby reducing the free carbon generated by discharge decomposition, and increases the stability of the environmentally friendly insulating gas. The environmentally friendly insulating gas that replaces sulfur hexafluoride in situ has excellent insulation tolerance, and has the advantages of high power frequency insulation strength and low carbon precipitation; it can play an excellent insulating function when applied, and has good use prospects in arc extinguishing or arc protection of basic electrical components.

Description

Technical Field

[0001] The present invention relates to the technical field of high-voltage or high-current switches with arc extinguishing or arc protection devices, and in particular to an environmentally friendly insulating gas for replacing sulfur hexafluoride in situ and application thereof. Background Art

[0002] The insulation performance of sulfur hexafluoride (SF6) is 2.5 times that of air, and its arc extinguishing performance is about 100 times that of air. Power equipment designed and developed around sulfur hexafluoride is widely used. Although sulfur hexafluoride has many excellent properties, it has a very strong greenhouse effect and is a restricted emission gas stipulated in many environmental conventions. The use and emission of sulfur hexafluoride have always been the focus of attention in the environmental field. In recent years, with the development of the electric power industry, sulfur hexafluoride, as the most representative insulating gas, has also shown an upward trend in usage. In response to global warming, the power industry has begun to use environmentally friendly macromolecular substances with a high content of fluorine as substitutes for sulfur hexafluoride, such as perfluoropentanone (C5F 10 O), perfluoroisobutyronitrile (C4F7N), trans-hexafluorobutene (HFO-1336mzz(E)), etc. However, the above alternative gases may have the defects of high boiling point and poor applicability in areas with low ambient temperature; or have technical problems such as high global warming potential (GWP) and high biological genotoxicity. In practical applications, it is difficult to meet the demand for replacing sulfur hexafluoride.

[0003] Among insulating gases, the liquefaction temperature of trifluoromethyl trifluorovinyl ether (C3F6O; Trifluoro(trifluoromethoxy)ethylene, TFE) is only -26 °C at normal pressure, and the liquefaction temperature can be further reduced after mixing with nitrogen / carbon dioxide background gas. At the same time, trifluoromethyl trifluorovinyl ether has excellent insulation performance and good stability, and has the ability to be used in gas insulation equipment. Based on this, the Chinese invention patent with publication number CN116635968A provides an insulating gas used for electrical insulation or arc extinguishing instead of SF6 gas and an electrical device using the insulating gas. The insulating gas is a mixed gas formed by 1 mol.%-60 mol.% of trifluoromethyl trifluorovinyl ether and the remainder of carbon dioxide, or a carrier gas composed of 1 mol.%-30 mol.% of oxygen and the remainder of carbon dioxide, and has the characteristics of low boiling point, high insulation resistance, low toxicity and low global warming index. It can replace sulfur hexafluoride, while maintaining high insulation and arc extinguishing capabilities, it reduces the global warming potential and reduces greenhouse gas emissions.

[0004] After the insulating gas breaks down at the power frequency, when the external applied voltage is removed, the insulating gas can quickly restore its insulation ability and maintain its working performance. Insulating gases are usually required to meet insulation strength performance indicators of more than 10 kV in electrical applications. When the insulating gas contains impurities, such as conductive vapor and conductive impurities, the breakdown voltage can be reduced. The inventors found in the application that the technical solutions of the prior art using perfluoropentanone, perfluoroisobutyronitrile, trans-hexafluorobutene, or trifluoromethyl trifluorovinyl ether, although optimizing the performance of insulating gases in terms of global warming potential, genotoxicity, and insulation endurance, generally have the technical problem of more carbon precipitation after discharge breakdown. As a conductive substance, carbon precipitation will seriously deteriorate the insulation reliability of electrical equipment. Even if the external applied voltage is removed, the precipitated carbon will still exist as a conductive impurity, reducing the performance of the insulating gas.

[0005] In summary, while meeting the requirements of excellent insulation performance, reducing the carbon precipitation content in gas-insulated equipment is of great significance for expanding the application of insulating gases. Summary of the invention

[0006] In view of the above-mentioned defects of the prior art, in a first aspect of the present invention, an environmentally friendly insulating gas for replacing sulfur hexafluoride in situ with excellent insulating properties and low carbon precipitation is provided, the components of which include trifluoromethyl trifluorovinyl ether and a carrier gas; wherein the content of trifluoromethyl trifluorovinyl ether is 70 mol.%-95 mol.%, and the content of the carrier gas is 5 mol.%-30 mol.%; the carrier gas includes at least one of nitrogen, carbon dioxide, and carbon tetrafluoride.

[0007] When using environmentally friendly insulating gas (hereinafter referred to as environmentally friendly insulating gas) that replaces sulfur hexafluoride in situ, the content of impurities must be strictly controlled to ensure its safe and efficient operation in electrical equipment. The sources of trifluoromethyl trifluorovinyl ether in the present invention are diverse, and it is appropriate to use commercially available industrial grade or higher purity trifluoromethyl trifluorovinyl ether to improve safety, insulation strength and other properties. In addition, due to the objective differences in the quality of different trifluoromethyl trifluorovinyl ether products, their boiling points fluctuate within a certain range. In order to meet the application requirements of most scenarios, the environmentally friendly insulating gas of the present invention is suitable for selecting trifluoromethyl trifluorovinyl ether with a boiling point lower than -20 ° C. Based on the chemical properties of trifluoromethyl trifluorovinyl ether, the carrier gas is suitable for using a gas that is chemically inert to trifluoromethyl trifluorovinyl ether in the application environment of this field, such as an inert diatomic molecule or a non-oxygen air component. Among them, nitrogen, carbon dioxide, and carbon tetrafluoride are widely available and easy to obtain, and are particularly suitable as the selection type of carrier gas of the present invention.

[0008] Preferably, the purity of the trifluoromethyl trifluorovinyl ether is ≥98 wt.%.

[0009] Preferably, the boiling point of the trifluoromethyl trifluorovinyl ether is less than -20°C.

[0010] Preferably, the global warming potential of the environmentally friendly insulating gas that replaces sulfur hexafluoride in situ is less than 1.

[0011] In a second aspect of the present invention, there is provided an application of the environmentally friendly insulating gas that replaces sulfur hexafluoride in situ according to the first aspect of the present invention, specifically as an insulating medium for basic electrical components for arc extinguishing or arc protection.

[0012] Preferably, the structure of the basic electrical components includes an insulating space for sealing and storing an environmentally friendly insulating gas that replaces sulfur hexafluoride in situ; the types of basic electrical components include electric switches, relays, selectors, and emergency protection devices.

[0013] The materials used to prepare the insulating space must have good chemical stability and must not react with the environmentally friendly insulating gas or its decomposition products. In order to achieve the best use effect, after the environmentally friendly insulating gas is filled into the insulating space of basic electrical components such as electric switches, relays, selectors, and emergency protection devices, it is appropriate to let it stand for a period of time to allow the gas to mix and evenly distribute inside the insulating space. In a few extreme use cases, the environmentally friendly insulating gas may be stratified under the influence of factors such as gravity, affecting its uniformity of distribution. Therefore, the vertical height of the insulating space should not be too high.

[0014] Further preferably, in the basic electrical component, the material constituting the insulating space is chemically inert to the environmentally friendly insulating gas that replaces sulfur hexafluoride in situ or to the decomposition products generated by the environmentally friendly insulating gas that replaces sulfur hexafluoride in situ during use.

[0015] Further preferably, after the environmentally friendly insulating gas that replaces sulfur hexafluoride in situ is filled into the insulating space and stored in a sealed manner, the obtained basic electrical components are left to stand for 20-24 hours before use.

[0016] Further preferably, the vertical height of the insulating space is ≤10 m.

[0017] From the perspective of the design of the technical solution, in order to solve the defects of the prior art (CN116635968A), the technical difficulty that the present invention needs to overcome mainly lies in how to use a simple method to reduce the carbon precipitation phenomenon while improving the power frequency insulation strength. Since the solutions of the prior art do not involve the technical problem of carbon precipitation, and the specific performance indicators of the insulating gas in this field may be affected by many factors, it is difficult for technical personnel in this field to anticipate or simply associate appropriate solutions during research and development. In particular, in the simultaneous satisfaction of multiple indicators, balancing the application needs of all aspects requires creative work.

[0018] During the research and development stage, the inventors studied the structure and application effects of trifluoromethyl trifluorovinyl ether and its isomers based on gas components. As shown in one or more comparative examples of the present invention, the isomers of trifluoromethyl trifluorovinyl ether are difficult to meet the power frequency insulation strength index of the present invention. Molecules with the same chemical formula have different effects due to different functional groups and molecular structures, and no regularity or predictable effects have been found.

[0019] In the technical scheme disclosed in the prior art, in order to meet the synergistic effect of insulation endurance, the content of trifluoromethyl trifluorovinyl ether needs to be controlled within the range of 1 mol.%-60 mol.%; when the carrier gas is carbon dioxide and oxygen, from the perspective of insulation and safety, the content of trifluoromethyl trifluorovinyl ether and oxygen is appropriately controlled within a lower range, otherwise there is a risk of flammability or even explosion. The inventors have found that the reason for the carbon precipitation phenomenon in this scheme is that the trifluoromethyl trifluorovinyl ether molecules decompose to form active groups under the action of high-energy arcs during the breakdown process. These active groups reorganize to form stable products including free carbon, and some free carbon is attached to the surface of electrical parts (such as electrodes), causing carbon precipitation. After comprehensively considering the defects of the prior art, the inventors proposed the above technical scheme. The design concept and principle of the present invention are to improve the insulation tolerance of environmentally friendly insulating gas by adjusting the component content, reduce the possibility of generating high-energy arcs, thereby reducing the free carbon generated by discharge decomposition, and increase the stability of environmentally friendly insulating gas. Regarding the carbon precipitation phenomenon, there is a technical solution in the art (CN103415895A) that uses oxygen or air to reduce carbon deposition on the electrode by using the reaction between oxygen and carbon. However, trifluoromethyl trifluorovinyl ether can produce a violent redox reaction with oxygen, especially at a high concentration as in the present invention. In order to eliminate the risks of combustion and explosion that may exist during use, its use requires strict oxygen control; therefore, the carbon precipitation phenomenon in the application environment of the present invention cannot be solved by oxygen oxidation. As presented in one or more embodiments of the present invention, after adding trifluoromethyl trifluorovinyl ether to the carrier gas, the insulation tolerance of the mixed gas is improved and the carbon precipitation is suppressed. The inventor considers that the liquefaction temperature of trifluoromethyl trifluorovinyl ether exceeds -25 ° C. In order to limit the mass fraction of carbon precipitation on the surface of the plate electrode after the mixed gas breaks down to no more than or approximately 20%, while meeting the liquefaction temperature and insulation tolerance of engineering applications, the present invention determines that the content of trifluoromethyl trifluorovinyl ether is 70 mol.%-95 mol.%, and the content of the carrier gas is 5 mol.%-30 mol.%.

[0020] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0021] The present invention provides an environmentally friendly insulating gas for replacing sulfur hexafluoride in situ, which has excellent insulation tolerance and has the advantages of high power frequency insulation strength and low carbon precipitation.

[0022] The present invention provides an application of an environmentally friendly insulating gas for replacing sulfur hexafluoride in situ, which has excellent insulating function and has good application prospects in arc extinguishing or arc protection of basic electrical components. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural diagram of the power frequency insulation strength test platform;

[0024] Figure 2 It is a schematic diagram of the structure of a ball-ball electrode;

[0025] Figure 3 Schematic diagram of the structure of the needle-plate electrode;

[0026] Figure 4 is the ball-and-stick model of the trifluoromethyl trifluorovinyl ether molecule;

[0027] Figure 5 Schematic diagram of the design and application process of environmentally friendly insulating gas for in-situ replacement of sulfur hexafluoride;

[0028] Figure 6 The power frequency insulation withstand capability of the insulating gas formed by trifluoromethyl trifluorovinyl ether and carbon dioxide and the variation law of the molar mixing ratio (k%) of trifluoromethyl trifluorovinyl ether;

[0029] Figure 7 This is the variation law of the carbon element fraction on the plate electrode surface and the molar mixing ratio of trifluoromethyl trifluorovinyl ether after the insulating gas formed by trifluoromethyl trifluorovinyl ether and carbon dioxide is broken down 100 times by power frequency. DETAILED DESCRIPTION

[0030] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. The experimental methods in the following examples without specifying specific conditions are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0031] In the following embodiments:

[0032] The trifluoromethyl trifluorovinyl ether and its isomers with a purity of >99.99% provided by Sanming Haisifu were used; the nitrogen, carbon dioxide, sulfur hexafluoride, perfluoropentanone, perfluoroisobutyronitrile and trans-hexafluorobutene gases with a purity of >99.99% provided by Newred were used.

[0033] Use Figure 1The power frequency insulation strength test platform shown in the figure measures the power frequency insulation strength of the selected insulating medium under different AC electric field conditions. The main structure and functions of the power frequency insulation strength test platform are as follows:

[0034] (1) Induction voltage regulator (single phase): supplies power to the low voltage winding of the transformer so that the output voltage of the transformer can be evenly adjusted over a wide range;

[0035] (2) Power frequency transformer: provides the power frequency voltage required for the experiment, with an output voltage range of 0-100 kV;

[0036] (3) Protection resistor: protects the transformer from damage in the event of flashover, with a resistance of 10 kΩ;

[0037] (4) Voltage divider capacitor: converts the experimental voltage to a range that can be measured by the voltmeter, with a voltage divider ratio of 500 pF / 500nF;

[0038] (5) Simulated gas chamber: The electrode defect model can be installed and adjusted inside the experimental gas chamber, and the insulating gas as the insulating medium can be filled in. The gas sampling port is used to collect gas samples before and after the experiment. The total volume of the gas chamber is 60 L. The tank body is made of 304 stainless steel and can withstand a gas pressure of more than 0.7 MPa. It contains a high-voltage guide rod with adjustable spacing.

[0039] Electrode defect models include: Figure 2 The ball-ball electrode shown and Figure 3 The needle-plate electrode shown in Figure 1. Among them, the ball-ball electrode is used to simulate a quasi-uniform electric field, while the needle-plate electrode is used to simulate an extreme electric field environment, that is, an extremely non-uniform electric field. During testing, the electrode defect model can be replaced to simulate different electric field environments.

[0040] The test process of power frequency insulation strength is as follows:

[0041] S1. Before the experiment, carefully wipe the inside of the simulated air chamber and the electrode defect model with anhydrous alcohol to remove the influence of impurities on the accuracy of the experimental results; after thorough cleaning, air dry, then install the electrode defect model, ensure that the experimental tank is completely sealed, and connect the experimental circuit;

[0042] S2. Check the air tightness of the simulated air chamber. Connect a vacuum pump to the air sampling port of the experimental air chamber, open the valve, and use the vacuum pump to evacuate the experimental air chamber. When the air pressure reading reaches 0.005 MPa, turn off the vacuum pump and let it stand for 1 hour to observe whether the air pressure reading changes. If the air pressure reading does not change significantly, it indicates that the air tightness of the experimental air chamber is good, and then the next step can be started. If the air pressure reading changes significantly, it proves that the experimental air chamber is leaking, and the cause of the leak needs to be checked.

[0043] S3. After the air tightness meets the requirements, the tank of the power frequency insulation strength test platform is evacuated and washed to eliminate the interference of other components in the air; the simulated air chamber is evacuated with a vacuum pump, and then 0.1 MPa buffer gas is introduced for washing and then vacuumed again. The whole process is repeated 3 times.

[0044] S4. Based on the component ratio of the tested insulating gas, the volume fraction of the filled gas is determined based on the partial pressure ratio using Dalton's law of partial pressure; when filling, first fill the gas with a lower content, then fill the gas with a higher content. For the environmentally friendly insulating gas that replaces sulfur hexafluoride in situ, first slowly introduce trifluoromethyl trifluorovinyl ether gas into the simulated gas chamber, then introduce the carrier gas, and after the filling is completed, let it stand for a period of time to allow it to be evenly mixed;

[0045] S5. Use the step-by-step pressure-increasing method to conduct a breakdown test on the mixed gas and measure the power frequency insulation strength.

[0046] Example 1

[0047] This embodiment provides an environmentally friendly insulating gas for replacing sulfur hexafluoride in situ, which is composed of 90 mol.% trifluoromethyl trifluorovinyl ether and 10 mol.% carbon dioxide.

[0048] Example 2

[0049] This embodiment provides an environmentally friendly insulating gas for replacing sulfur hexafluoride in situ, which is composed of 90 mol.% trifluoromethyl trifluorovinyl ether and 10 mol.% nitrogen.

[0050] Example 3

[0051] This embodiment provides an environmentally friendly insulating gas for replacing sulfur hexafluoride in situ, which is composed of 80 mol.% trifluoromethyl trifluorovinyl ether and 20 mol.% carbon dioxide.

[0052] Example 4

[0053] This embodiment provides an environmentally friendly insulating gas for replacing sulfur hexafluoride in situ, which is composed of 70 mol.% trifluoromethyl trifluorovinyl ether and 30 mol.% carbon dioxide.

[0054] Example 5

[0055] This embodiment provides an environmentally friendly insulating gas for replacing sulfur hexafluoride in situ, which is composed of 80 mol.% trifluoromethyl trifluorovinyl ether and 20 mol.% nitrogen.

[0056] Example 6

[0057] This embodiment provides an environmentally friendly insulating gas for replacing sulfur hexafluoride in situ, which is composed of 70 mol.% trifluoromethyl trifluorovinyl ether and 30 mol.% nitrogen.

[0058] Comparative Example 1

[0059] The insulating gas in this comparative example is sulfur hexafluoride.

[0060] Comparative Example 2

[0061] The insulating gas of this comparative example is composed of 90 mol.% hexafluoroacetone and 10 mol.% carbon dioxide.

[0062] Comparative Example 3

[0063] The insulating gas of this comparative example is composed of 90 mol.% hexafluorooxetane and 10 mol.% carbon dioxide.

[0064] Comparative Example 4

[0065] The insulating gas of this comparative example is composed of 90 mol.% of pentafluoropropionyl fluoride and 10 mol.% of carbon dioxide.

[0066] Comparative Example 5

[0067] The insulating gas of this comparative example is composed of 90 mol.% hexafluoropropylene oxide and 10 mol.% carbon dioxide.

[0068] Comparative Example 6

[0069] The insulating gas of this comparative example is composed of 50 mol.% of trifluoromethyl trifluorovinyl ether and 50 mol.% of carbon dioxide.

[0070] Comparative Example 7

[0071] The insulating gas of this comparative example is composed of 30 mol.% of trifluoromethyl trifluorovinyl ether and 70 mol.% of carbon dioxide.

[0072] Comparative Example 8

[0073] The insulating gas of this comparative example is composed of 50 mol.% of trifluoromethyl trifluorovinyl ether and 50 mol.% of nitrogen.

[0074] Comparative Example 9

[0075] The insulating gas of this comparative example is composed of 30 mol.% of trifluoromethyl trifluorovinyl ether and 70 mol.% of nitrogen.

[0076] Comparative Example 10

[0077] The insulating gas of this comparative example is composed of 7.5 mol.% perfluoropentanone and 92.5 mol.% carbon dioxide.

[0078] Comparative Example 11

[0079] The insulating gas of this comparative example is composed of 4 mol.% perfluoroisobutyronitrile and 96 mol.% carbon dioxide.

[0080] Comparative Example 12

[0081] The insulating gas of this comparative example is composed of 20 mol.% of trans-hexafluorobutene and 80 mol.% of carbon dioxide.

[0082] In the embodiments of the present invention, trifluoromethyl trifluorovinyl ether is used. Figure 4 For its ball-and-stick model, the compound has good stability, excellent insulation properties and low liquefaction temperature. Figure 5 The figure is a schematic diagram of the design and application process of an environmentally friendly insulating gas that replaces sulfur hexafluoride in situ. In order to replace the environmental problems caused by sulfur hexafluoride, the field is actively looking for its substitutes. To this end, the inventor studied trifluoromethyl trifluorovinyl ether with a molecular formula of C3F6O and its isomers, adjusted the component ratio and tested its situation in practical application.

[0083] The component contents of the above comparative examples are formulated based on common insulating gases in the prior art or for specific research purposes. Comparative Example 1 is the most widely used sulfur hexafluoride gas in the art; Comparative Examples 2-5 are isomers of trifluoromethyl trifluorovinyl ether; Comparative Examples 6-9 use a trifluoromethyl trifluorovinyl ether ratio lower than the range of the present invention, i.e., the range selected in the invention patent with publication number CN116635968A; Comparative Examples 10-12 are common sulfur hexafluoride substitutes in the art.

[0084] Test Example 1

[0085] This test adopts a power frequency insulation strength test platform, and uses the environmentally friendly insulating gas that replaces sulfur hexafluoride in situ of Examples 1-6 and the insulating gas of Comparative Examples 1-9 as the insulating medium to measure the power frequency insulation strength thereof, so as to study the insulation performance of the environmentally friendly insulating gas that replaces sulfur hexafluoride in situ of the present invention.

[0086] During the test, a quasi-uniform electric field was simulated with a ball-ball electrode, and the insulating medium was subjected to 20 power frequency breakdowns in different equipment pressure environments (0.10 MPa, 0.15 MPa, 0.20 MPa, 0.25 MPa, and 0.30 MPa) using a step-by-step pressure increase method. Each breakdown interval was 30 minutes, and the average value of the 20 breakdown voltages was taken as the power frequency insulation strength of the insulating medium. The power frequency insulation strength test results of the above embodiments and comparative examples are shown in Table 1.

[0087] Table 1: Power frequency insulation strength of insulating media in the embodiments and comparative examples

[0088]

[0089] It can be seen from the test results in Table 1 that the power frequency insulation strength of the environmentally friendly insulating gas that replaces sulfur hexafluoride in situ in Examples 1 and 2 is similar to that of Comparative Example 1, that is, the power frequency insulation strength under various gas pressure conditions is equivalent to that of sulfur hexafluoride, and can meet the application requirements of operating in various equipment pressure environments. In contrast, although the power frequency insulation strength of Examples 3 to 6 is not as good as that of Examples 1 and 2, they can also meet the basic gas insulated equipment requirements, and their minimum insulation tolerance is maintained above 10 kV, meeting the technical purpose of replacing sulfur hexafluoride in applications. The results of Comparative Examples 2-9 show that compared with the isomer formula of trifluoromethyl trifluorovinyl ether and other trifluoromethyl trifluorovinyl ether contents (less than 60 mol.%), the environmentally friendly insulating gas that replaces sulfur hexafluoride in situ of the present invention exhibits excellent insulation tolerance.

[0090] Test Example 2

[0091] This test uses a power frequency insulation strength test platform, and selects a needle-plate electrode as an electrode defect model to simulate the extreme electric field environment in the device. In different equipment pressure environments (0.10 MPa, 0.15 MPa, 0.20 MPa, 0.25 MPa, 0.30 MPa), the environmentally friendly insulating gas of Examples 1-6 that replaces sulfur hexafluoride in situ and the insulating gas of Comparative Examples 6-12 are respectively broken down 100 times by power frequency under the extremely non-uniform electric field created by the needle-plate electrode. The mass fraction of carbon elements in the core area of ​​the needle-plate electrode surface (i.e., the plate electrode surface) is detected by an energy dispersive spectrometer (EDS) to study the carbon precipitation in the actual application process. The test results of the carbon precipitation content of the above embodiments and comparative examples are shown in Table 2.

[0092] Table 2: Carbon element fraction on the surface of plate electrode after power frequency breakdown test of insulating medium in the embodiments and comparative examples

[0093]

[0094] It can be seen from the test results in Table 2 that after 100 power frequency breakdowns, the mass fraction of carbon elements on the plate electrode surface of the environmentally friendly insulating gas of Examples 1 and 2 that replaces sulfur hexafluoride in situ is much smaller than that of Comparative Examples 6-12. Under various gas pressure conditions, the carbon precipitation of the environmentally friendly insulating gas that replaces sulfur hexafluoride in situ proposed by the present invention is far better than that of various common insulating gases. Comparative Examples 6-9 also use trifluoromethyl trifluorovinyl ether, but their carbon mass fraction is significantly higher than that of Examples 1-6. This is because when the content of trifluoromethyl trifluorovinyl ether is reduced, the insulation tolerance of the insulating gas decreases, that is, it is easier to generate high-energy arcs, and the mixed stability decreases. More free carbon is generated through discharge decomposition, and it is attached to the surface of the plate electrode to show a higher carbon mass fraction. Therefore, the environmentally friendly insulating gas that replaces sulfur hexafluoride in situ of the present invention enhances the insulation reliability of operation in various gas-insulated equipment.

[0095] Test Example 3

[0096] This test example uses the power frequency insulation strength test platform and conducts the test in the same way as in Test Example 1 and Test Example 2. Carbon dioxide is used as the carrier gas to study the relationship between the power frequency insulation withstand capacity of the insulating gas and the carbon content on the plate electrode surface after 100 power frequency breakdowns at different molar mixing ratios of trifluoromethyl trifluorovinyl ether. The power frequency insulation withstand capacity of the insulating gas formed by trifluoromethyl trifluorovinyl ether and carbon dioxide and the change law of the molar mixing ratio of trifluoromethyl trifluorovinyl ether are shown in the figure. Figure 6 As shown; after 100 power frequency breakdowns, the change rules of the carbon content on the plate electrode surface and the molar mixing ratio of trifluoromethyl trifluorovinyl ether are as follows Figure 7 shown.

[0097] Depend on Figure 6 It can be seen that with the increase of the content of trifluoromethyl trifluorovinyl ether, the power frequency insulation withstand capacity of the insulating gas shows an upward trend under various gas pressure environments. Figure 7 It is confirmed that the increase of trifluoromethyl trifluorovinyl ether content helps to reduce the carbon element fraction on the electrode surface. Considering that the liquefaction temperature of pure trifluoromethyl trifluorovinyl ether usually requires a high pressure environment and exceeds -25 °C, its content should not exceed 95 mol.% from the perspective of engineering application liquefaction temperature; in addition, in order to limit the mass fraction of carbon precipitation on the plate electrode surface after the mixed gas breaks down to no more than or approximately 20%, while meeting the insulation tolerance, the inventors determined that the content of trifluoromethyl trifluorovinyl ether is 70 mol.%-95 mol.%, and the content of carrier gas is 5 mol.%-30 mol.%.

[0098] 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. An environmentally friendly insulating gas for replacing sulfur hexafluoride in situ, characterized in that: The components of the environmentally friendly insulating gas for in-situ replacement of sulfur hexafluoride are composed of trifluoromethyl trifluorovinyl ether and a carrier gas; wherein the content of trifluoromethyl trifluorovinyl ether is 70 mol.%-95 mol.%, and the content of the carrier gas is 5 mol.%-30 mol.%; and the carrier gas includes at least one of nitrogen, carbon dioxide, and carbon tetrafluoride.

2. The environmentally friendly insulating gas for replacing sulfur hexafluoride in situ according to claim 1, characterized in that: The purity of the trifluoromethyl trifluorovinyl ether is ≥98 wt.%.

3. The environmentally friendly insulating gas for in-situ replacement of sulfur hexafluoride according to claim 1, characterized in that: The boiling point of trifluoromethyl trifluorovinyl ether is less than -20°C.

4. The environmentally friendly insulating gas for in-situ replacement of sulfur hexafluoride according to claim 1, characterized in that: The global warming potential of the environmentally friendly insulating gas that replaces sulfur hexafluoride in situ is less than 1.

5. An application of the environmentally friendly insulating gas for in-situ replacement of sulfur hexafluoride as claimed in any one of claims 1 to 4, characterized in that: The environmentally friendly insulating gas that replaces sulfur hexafluoride in situ is used as the insulating medium of basic electrical components for arc extinguishing or arc protection.

6. The use of an environmentally friendly insulating gas for replacing sulfur hexafluoride in situ according to claim 5, characterized in that: The structure of the basic electrical components includes an insulating space for sealing and storing an environmentally friendly insulating gas that replaces sulfur hexafluoride in situ; the types of basic electrical components include electric switches, relays, selectors, and emergency protection devices.

7. The use of an environmentally friendly insulating gas for replacing sulfur hexafluoride in situ according to claim 6, characterized in that: In the basic electrical component, the material constituting the insulating space is chemically inert to the environmentally friendly insulating gas that replaces sulfur hexafluoride in situ or to the decomposition products generated by the environmentally friendly insulating gas that replaces sulfur hexafluoride in situ during use.

8. The use of an environmentally friendly insulating gas for replacing sulfur hexafluoride in situ according to claim 6, characterized in that: After the environmentally friendly insulating gas that replaces sulfur hexafluoride in situ is filled into the insulating space and sealed for storage, the obtained basic electrical components are left to stand for 20-24 hours before use.

9. The use of an environmentally friendly insulating gas for replacing sulfur hexafluoride in situ according to claim 6, characterized in that: The vertical height of the insulating space is ≤10 m.

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