Insulating medium, preparation method thereof and electrical device

Abstract

The invention relates to the technical field of electrical equipment insulating media, and discloses an insulating medium, a preparation method thereof and an electrical device, the insulating medium comprises a mixed gas, the mixed gas comprises an insulating gas, a buffer gas and a heat conduction gas; and the heat conduction nano particles are suspended in the mixed gas. The insulating medium has excellent insulating property and heat-conducting property, and has application potential in a high-power density scene.

Description

Technical Field

[0001] This application relates to the field of electrical equipment insulation medium technology, specifically to insulation medium and its preparation method, and electrical devices. Background Technology

[0002] In high-voltage and ultra-high-voltage power systems, SF6 is widely used as the primary insulating and arc-quenching medium in gas-insulated switchgear. However, as one of the most potent greenhouse gases known, SF6's environmental impact has attracted widespread international attention. SF6 has a global warming potential of 24,300, more than 20,000 times that of carbon dioxide, and its atmospheric lifetime can reach 3,200 years. It hardly participates in atmospheric chemical reactions, making it highly susceptible to long-term cumulative effects.

[0003] Currently, new environmentally friendly insulating gases, such as perfluoroisobutyronitrile (PFOB) and perfluoropentanone (PFA), are gradually becoming potential substitutes for SF6 due to their lower global warming potential and stronger insulating capabilities. When mixed with buffer gases like CO2, these gases exhibit significantly lower liquefaction temperatures, resulting in more stable system operation. Furthermore, experiments and some engineering applications have verified that they can achieve or approach the insulation level of SF6 under the same pressure conditions. However, for high-end gas-insulated equipment, the significant heat generated during operation places higher demands on the thermal conductivity of the insulating medium. Therefore, developing an insulating medium with excellent thermal conductivity, such as combinations of PFOB / CO2 and perfluoropentanone / CO2, has become a key focus of current alternative technology research. Summary of the Invention

[0004] This application aims to at least partially solve one of the technical problems in the related art. Therefore, one objective of this application is to provide an insulating medium and its preparation method, as well as an electrical device thereof. The insulating medium of this application has excellent insulation and thermal conductivity properties, and is safe and environmentally friendly, posing no threat to the natural environment.

[0005] A first aspect of this application provides an insulating medium comprising: A mixed gas, comprising an insulating gas, a buffer gas, and a thermally conductive gas; Thermally conductive nanoparticles are suspended in the mixed gas. This application innovatively adds thermally conductive gas and thermally conductive nanoparticles to an insulating medium, thereby improving the thermal conductivity of the insulating medium and giving it multiple properties such as thermal conductivity and insulation.

[0006] In some embodiments, the volume ratio of the insulating gas, the buffer gas, the thermally conductive gas, and the thermally conductive nanoparticles is 10~25:65~85:5~10:0.1~0.5. This helps to obtain an insulating medium with excellent thermal conductivity and insulation properties, and the aforementioned insulating medium also exhibits strong stability.

[0007] In some embodiments, the insulating gas satisfies at least one of the following conditions: The insulating gas includes at least one of perfluoroisobutyronitrile, perfluoropentanone, perfluorohexanone, and perfluoromethyl vinyl ether. The purity of the insulating gas is ≥99.5%. This helps to obtain an insulating medium with excellent insulation performance and environmental friendliness.

[0008] In some embodiments, the buffer gas satisfies at least one of the following conditions: The buffer gas includes at least one of carbon dioxide, nitrogen, and dry air; The purity of the buffer gas is ≥99.9%; The moisture content of the dry air is <100 ppm. This helps to lower the liquefaction temperature of the insulating medium and further improve its stability.

[0009] In some embodiments, the heat-conducting gas satisfies at least one of the following conditions: The heat-conducting gas includes at least one of helium, neon, argon, krypton, and xenon. The purity of the heat-conducting gas is ≥99.9%. This helps to obtain an insulating medium with excellent thermal conductivity.

[0010] In some embodiments, the thermally conductive nanoparticles satisfy at least one of the following conditions: The thermally conductive nanoparticles include at least one of Al2O3 and TiO2; The particle size of the thermally conductive nanoparticles is <50nm; The thermally conductive nanoparticles have a thermal conductivity of 15 W / (m·K) to 40 W / (m·K). This helps to further improve the thermal conductivity of the insulating medium.

[0011] In a second aspect of this application, a method for preparing the aforementioned insulating medium is provided, comprising: The insulating gas and the buffer gas are mixed to obtain a premixed gas; The heat-conducting gas is mixed with the premixed gas to obtain a mixed gas; The insulating medium is obtained by suspending thermally conductive nanoparticles in the mixed gas. This preparation method is simple to operate, and the resulting insulating medium has excellent thermal conductivity and insulation properties.

[0012] In some embodiments, mixing the insulating gas and the buffer gas includes: introducing the insulating gas and the buffer gas into a gas mixer according to their liquefaction temperatures from high to low for preparation. This yields a premixed gas.

[0013] In some embodiments, mixing the thermally conductive gas with the premixed gas includes simultaneously introducing the thermally conductive gas and the premixed gas into a gas mixer for preparation. This yields a mixed gas.

[0014] In some embodiments, suspending the thermally conductive nanoparticles in the mixed gas includes: The thermally conductive nanoparticles are introduced into the mixed gas over a period of 10 to 30 minutes. This helps the nanoparticles to be uniformly suspended in the mixed gas, thus obtaining the insulating medium.

[0015] In a third aspect of this application, an electrical device is provided, comprising the aforementioned insulating medium. Therefore, this electrical device possesses excellent insulation and thermal conductivity.

[0016] In some embodiments, the electrical device described above includes at least one of gas-insulated switchgear, circuit breaker, instrument transformer, and switch cabinet. Attached Figure Description

[0017] Figure 1 This is a flowchart of the preparation of an insulating medium in one embodiment of this application.

[0018] Figure 2 This is a comparison diagram of the breakdown field strength and thermal conductivity of the insulating media in Embodiment 1 and Comparative Example 1 of this application. Detailed Implementation

[0019] The embodiments of this application are described in detail below. The embodiments described below are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0020] This application is based on the inventor's following discoveries and understandings: In related technologies, insulating media such as perfluoroisobutyronitrile / CO2 and perfluoropentanone / CO2 combinations can be directly used in electrical insulation equipment. These insulating media not only possess excellent insulation properties but also have a very low greenhouse effect. However, due to their lack of excellent thermal conductivity, they are unsuitable for high-end insulation equipment with high heat generation, thus limiting their application potential in high-power-density scenarios. Therefore, the inventors considered introducing components with thermal conductivity into these insulating media to improve their overall thermal management capabilities. Specifically, the inventors noted that many gases not only have extremely high thermal conductivity but also possess certain electrical insulation properties. Furthermore, thermally conductive nanoparticles also have excellent thermal conductivity and are used in many other fields to improve thermal conductivity. However, there are many types of gases with thermal conductivity. Choosing an unsuitable thermally conductive gas may cause it to react with the insulating medium itself, affecting the insulation performance of the insulating medium. In addition, thermally conductive nanoparticles are prone to agglomeration in gaseous media, resulting in uneven dispersion and thus affecting their thermal conductivity. Therefore, the selection of thermally conductive gases and how to introduce thermally conductive nanoparticles into gaseous insulating media to improve the thermal conductivity of the insulating medium are current problems.

[0021] In response, the inventors conducted in-depth research and discovered that some light inert gases have excellent thermal conductivity, with a thermal conductivity coefficient more than ten times that of SF6. At the same time, they are chemically stable and hardly react with other gas components and equipment materials. They can significantly improve the thermal conduction efficiency of mixed gases while having little or no impact on insulation performance under operating gas pressure. On the other hand, nanoparticles can only be uniformly dispersed in the gas medium under the presence of external force. If the gas is placed in a closed space, it will form a stable airflow. Thus, the generated airflow can act as an external force to promote the uniform dispersion of nanoparticles in the gas medium.

[0022] Based on the above understanding, the inventors considered introducing an appropriate amount of thermally conductive gas and thermally conductive nanoparticles into the insulating medium in related technologies as thermally conductive enhancement components, utilizing their extremely high thermal conductivity to improve the overall thermal conductivity of the mixed gas.

[0023] In view of this, the first aspect of this application proposes an insulating medium comprising a mixed gas and thermally conductive nanoparticles suspended in the mixed gas, wherein the mixed gas includes an insulating gas, a buffer gas, and a thermally conductive gas. The insulating medium of this application introduces thermally conductive components, namely thermally conductive gas and thermally conductive nanoparticles. The thermally conductive gas can transfer energy through intermolecular collisions, and due to its excellent thermal conductivity, it can transfer heat from high-temperature regions to low-temperature regions. Furthermore, the thermally conductive nanoparticles can build thermally conductive bridges between gas molecules. During heat transfer, the thermally conductive nanoparticles can capture heat and rapidly transfer it away through their high thermal conductivity. Thus, the aforementioned thermally conductive components can significantly improve thermal conductivity without substantially affecting the insulation performance, achieving a balance between the thermal conductivity and insulation performance of the insulating medium, effectively addressing the problem of insufficient thermal conductivity in environmentally friendly insulating media.

[0024] In some embodiments, the volume ratio of the insulating gas, the buffer gas, the thermally conductive gas, and the thermally conductive nanoparticles is 10~25:65~85:5~10:0.1~0.5. Specifically, the volume ratio can be 10:65:5:0.1, 15:65:5:0.1, 20:65:5:0.1, 25:65:5:0.1, 10:75:5:0.1, 10:85:5:0.1, or 10:65:8 Volume ratios such as 0.1, 10:65:10:0.1, 10:65:5:0.3, 10:65:5:0.5, 20:75:5:0.1, 20:75:8:0.3, 20:85:5:0.5, 25:65:10:0.5, 25:85:10:0.5, and 18:75:8:0.3 help to obtain insulating media with better stability, and the insulating media has excellent thermal conductivity and insulation properties. Specifically, the volume ratio between the insulating gas and the buffer gas was calculated using the Levenberg-Marquardt algorithm and the improved formula for the thermal conductivity of the mixed gas. The specific formula is as follows:

[0025] Among them, y i k is the volume fraction of the insulating gas. i k is the thermal conductivity of the insulating gas. j φ is the thermal conductivity of the buffer gas. ij Let μi be the interaction coefficient between the insulating gas and the buffer gas, μj be the viscosity of the insulating gas, Mi be the molecular weight of the insulating gas, and Mj be the molecular weight of the buffer gas. When the insulating gas and the buffer gas are multiple gases, all gases need to be summed in the calculation. Maximize the thermal conductivity of the mixed gas (k... mixThe resulting volume fraction of insulating gas is 10%-25%, and the volume fraction of buffer gas is 65%-85%. Further limiting the volume fraction of thermally conductive gas to 5%-10% and the volume fraction of thermally conductive nanoparticles to 0.1%-0.5%, within these ranges helps achieve a balance between the thermal conductivity and insulation properties of the insulating medium. This largely avoids problems such as the instability and reduced insulation properties caused by an excessively high volume fraction of thermally conductive gas, and the reduced gas thermal conductivity caused by an excessively low volume fraction of thermally conductive gas. It also largely avoids problems such as uneven dispersion and reduced stability of the insulating medium caused by an excessively high volume fraction of thermally conductive nanoparticles, and the negative impact on the thermal conductivity of the insulating medium caused by an excessively low volume fraction of thermally conductive nanoparticles.

[0026] In some embodiments, the insulating gas includes at least one of perfluoroisobutyronitrile, perfluoropentanone, perfluorohexanone, and perfluoromethyl vinyl ether. In terms of performance, the aforementioned fluorinated insulating gases have high dielectric strength and high insulation strength. Under the same operating conditions, using these gases can reduce equipment size and improve insulation reliability, making them particularly suitable for high-voltage and ultra-high-voltage electrical equipment. Simultaneously, these insulating gases have strong arc-extinguishing capabilities, quickly extinguishing the arc generated during the disconnection of electrical equipment, reducing arc damage to the equipment, and improving equipment operational stability. Furthermore, the aforementioned insulating gases have low global warming potential, significantly reducing their impact on global climate change and meeting environmental protection requirements.

[0027] In some embodiments, the purity of the insulating gas is ≥99.5%, specifically, it can be 99.5%, 99.6%, 99.7%, 99.8%, 99.9%, 99.99%, etc. The purity of the insulating gas within the above range helps to ensure that the insulating medium has excellent insulating performance. The molecular structure of high-purity insulating gas is stable, thus having stable chemical properties. Long-term direct contact with equipment will basically not cause equipment corrosion. It can basically avoid the problem of a significant decrease in insulation performance caused by the purity of the insulating gas being too low, which would affect the power system and accelerate equipment aging and corrosion.

[0028] In some embodiments, the buffer gas includes at least one of carbon dioxide, nitrogen, and dry air. The aforementioned insulating gases are prone to liquefaction at low temperatures, leading to a sharp drop in insulation performance. Mixing in buffer gases, such as nitrogen and carbon dioxide with extremely low boiling points (-195.8°C and -78.5°C respectively), can lower the liquefaction temperature of the mixed gas, allowing it to remain gaseous under low-temperature conditions and ensuring stable equipment operation. Furthermore, the large molecular weight of insulating gases results in poor fluidity; adding the buffer gas can significantly improve the diffusion and fluidity of the mixed gas, facilitating a more uniform distribution of the insulating medium.

[0029] Furthermore, the purity of the buffer gas is greater than or equal to 99.9%, specifically, it can be 99.9%, 99.91%, 99.92%, 99.93%, 99.94%, 99.95%, 99.96%, 99.97%, 99.98%, 99.99%, etc. The purity of the buffer gas within the above range is beneficial to improving the fluidity of the insulating medium and has basically no impact on the insulating performance of the insulating medium. If the purity of the buffer gas is too low, the impurities in it, such as moisture and organic matter, may directly damage the insulating performance of the insulating medium.

[0030] In some embodiments, when dry air is used as the buffer gas, the moisture content in the dry air is <100 ppm. Specifically, it can be 1 ppm, 10 ppm, 20 ppm, 30 ppm, 40 ppm, 50 ppm, 60 ppm, 70 ppm, 80 ppm, 90 ppm, 99 ppm, etc. The moisture content in the dry air within the above range can basically ensure that the insulation performance of the insulating medium is not affected. When the moisture content in the dry air is too high, the moisture will react with the fluorine-containing insulating gas under high temperature and high pressure conditions to generate corrosive substances such as hydrofluoric acid, which may lead to a decrease in insulation performance. At the same time, excessive moisture will reduce the dielectric strength of the gas and increase the risk of partial discharge.

[0031] In some embodiments, the heat-conducting gas includes at least one of helium, neon, argon, krypton, and xenon. These heat-conducting gases have high thermal conductivity, and when mixed into the insulating medium, they can significantly enhance the thermal conductivity of the mixed gas, accelerate the diffusion of heat from inside the equipment to the external environment, avoid excessively high local temperatures, and ensure that the equipment operates within the normal temperature range. At the same time, the above-mentioned heat-conducting gases are all inert gases with stable chemical properties, do not react with other components in the insulating medium, and have virtually no impact on the insulation performance.

[0032] Furthermore, the purity of the aforementioned heat-conducting gas is ≥99.9%, specifically, it can be 99.9%, 99.91%, 99.92%, 99.93%, 99.94%, 99.95%, 99.96%, 99.97%, 99.98%, 99.99%, etc. Heat-conducting gases with purity within the above range have excellent thermal conductivity, which can basically avoid the reduction in thermal conductivity caused by excessively low purity of the heat-conducting gas, as well as the impact of other impurities contained therein on the insulation performance of the insulating medium.

[0033] In some embodiments, the thermally conductive nanoparticles include at least one of Al2O3 and TiO2. These thermally conductive nanoparticles have a high thermal conductivity and a large specific surface area, which can accelerate heat transfer in a mixed gas. At the same time, these thermally conductive nanoparticles are resistant to high and low temperatures and have stable chemical properties, are not prone to reaction, and can exist stably in an insulating medium.

[0034] In some embodiments, the particle size of the thermally conductive nanoparticles is <50 nm. Specifically, the particle size of the thermally conductive nanoparticles can be 1 nm, 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 49 nm, etc. The particle size of the thermally conductive nanoparticles within the above range has a high specific surface area, thereby exhibiting excellent thermal conductivity. At the same time, the particle size within the above range helps to disperse evenly in the insulating medium, thereby avoiding local overheating. This can basically avoid problems such as uneven distribution and reduced thermal conductivity caused by excessively large particle size of the thermally conductive nanoparticles.

[0035] In some embodiments, the thermal conductivity of the thermally conductive nanoparticles is 15 W / (m·K) to 40 W / (m·K). Specifically, the thermal conductivity can be 15 W / (m·K), 20 W / (m·K), 25 W / (m·K), 30 W / (m·K), 35 W / (m·K), 40 W / (m·K), etc. A thermal conductivity within the above range helps to balance thermal conductivity and insulation performance. It can basically avoid the problems of damage to the internal structure of the insulating medium caused by excessively high thermal conductivity of nanoparticles, which would affect the equipment, and the problems of insignificant thermal conductivity caused by excessively low thermal conductivity of nanoparticles.

[0036] In a second aspect of this application, a method for preparing the aforementioned insulating medium is provided, referring to... Figure 1 ,include: S10: Mix the insulating gas and the buffer gas to obtain a premixed gas.

[0037] In this step, insulating gas and buffer gas can be introduced into a gas mixer at room temperature according to their liquefaction temperature from high to low for preparation, and the prepared premixed gas can be stored in a steel cylinder for later use.

[0038] Specifically, the liquefaction temperature of insulating gas is usually higher than that of buffer gas. Therefore, the insulating gas can be introduced into the gas mixer first, and then the buffer gas can be introduced into the gas mixer to obtain a premixed gas.

[0039] Specifically, under standard atmospheric pressure, the liquefaction temperatures of perfluoroisobutyronitrile (PFOBN) are -29°C, perfluoropentanone (PFOP) is 49°C, perfluorohexanone (PFH) is 52.6°C, perfluoromethyl vinyl ether (PFME) is -22°C, carbon dioxide is -78°C, nitrogen is -195.8°C, and dry air is -191°C. Understandably, in practical operation, the gas can be introduced into the gas mixer in descending order of liquefaction temperature for preparation.

[0040] S20: Mix the heat-conducting gas with the premixed gas to obtain a mixed gas.

[0041] In this step, the heat-conducting gas and the aforementioned premixed gas can be simultaneously introduced into the gas mixer for configuration, and the configured mixed gas can be stored in a steel cylinder for later use. Alternatively, the configured mixed gas can be directly charged into the target equipment.

[0042] In some embodiments, the components in the mixed gas do not liquefy at pressures of 0.1 MPa to 0.7 MPa. The above pressure range refers to the pressure of the target equipment or sealed cylinder. Within the above pressure range, the non-liquefaction of each component can basically ensure the normal chemical stability, insulation performance, thermal conductivity, and other properties of the mixed gas. It can also basically avoid the reduction of intermolecular distance and enhanced interaction caused by the liquefaction of one component, which would lead to a chemical reaction that would affect thermal conductivity, insulation performance, etc.

[0043] S30: Suspend thermally conductive nanoparticles in the mixed gas to obtain the insulating medium.

[0044] In this step, thermally conductive nanoparticles can be injected into the cylinder or target device containing the mixed gas using the side channel of a three-way pipe at a predetermined amount within 10 to 30 minutes (the thermally conductive nanoparticles need to be added through the three-way pipe before the gas pressure is introduced). The specific injection time can be 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, etc. Since the mixed gas can form a pressurized airflow in the cylinder or target device, the airflow can help the thermally conductive nanoparticles to be uniformly suspended in the mixed gas. Therefore, the above-mentioned time helps the thermally conductive nanoparticles to be uniformly suspended in the mixed gas, resulting in a more stable insulating medium. If the injection time is too short, the thermally conductive nanoparticles will locally aggregate, thereby reducing the stability and thermal conductivity of the insulating medium. If the injection time is too long, gas leakage will occur and time will be wasted.

[0045] Specifically, the mixed gas is relatively sealed in a gas cylinder or target device, with a pressure difference between it and the external environment. When nanoparticles are injected, the mixed gas in the gas cylinder or target device will start to flow in order to balance the pressure difference with the outside world, thus forming an airflow. The airflow has a certain impact force, and the continuously flowing airflow will exert forces on the heat-conducting nanoparticles in various directions, causing the nanoparticles to diffuse to different areas along with the flow of the mixed gas, thereby being evenly dispersed in the mixed gas.

[0046] In some embodiments, to avoid affecting the stability of the insulating medium, it is filled into the target device within 1 hour after the insulating medium is prepared. This avoids the thermally conductive nanoparticles from attracting each other and agglomerating due to prolonged storage of the insulating medium, thus affecting the thermal conductivity of the insulating medium.

[0047] In a third aspect of this application, an electrical device is proposed that includes the aforementioned insulating medium, thereby possessing all the advantages of the aforementioned insulating medium, which will not be elaborated further here.

[0048] In some embodiments, the aforementioned electrical device includes at least one of gas-insulated switchgear (GIS), circuit breaker, instrument transformer, and switchgear. During operation, the core components of the aforementioned electrical device generate a large amount of heat due to resistance loss, arc energy, etc. Using the insulating medium of this application can efficiently dissipate this heat, essentially preventing problems such as discharge and accelerated component aging in the electrical device.

[0049] The present application will now be described with reference to specific embodiments. It should be noted that these embodiments are merely descriptive and do not limit the present application in any way. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in the art or in accordance with the product manual.

[0050] Example 1 The specific method for preparing the insulating medium is as follows: S10: Pass 15 parts by volume of perfluoroisobutyronitrile and 80 parts by volume of carbon dioxide into the gas mixing instrument in sequence, and then fill the prepared premixed gas into the steel cylinder.

[0051] S20: The above premixed gas and 5 parts by volume of helium are simultaneously introduced into the gas mixing instrument, and the prepared mixed gas is loaded into a steel cylinder.

[0052] S30: In a vacuum chamber, Al2O3 nanoparticles with a particle size of 20nm and a volume fraction of 0.2 are injected into a steel cylinder containing a mixed gas for 15 minutes to obtain the insulating medium of this application. Examples 2-10 Same as Example 1, the main differences are detailed in Table 1.

[0053] Comparative Example 1 15 parts by volume of perfluoroisobutyronitrile and 80 parts by volume of carbon dioxide were sequentially introduced into a gas mixing instrument, and the prepared mixed gas was loaded into a steel cylinder as an insulating medium.

[0054] Comparative Examples 2-3 Similar to Comparative Example 1, the main differences are detailed in Table 1.

[0055] Performance testing The prepared insulating medium was set to a pressure of 0.14 MPa and the breakdown field strength was tested using 5 mm pitch ball-plate electrodes in accordance with the IEC60243 test standard. Transient hot-wire thermal conductivity tests were performed on insulating media using the Hot Disk TPS system.

[0056] The breakdown field strength and thermal conductivity of the insulating media prepared in Example 1 and Comparative Example 1 are shown in the figure. Figure 2 As can be seen, compared with Comparative Example 1, the thermal conductivity of the insulating medium in Example 1 is increased by about 21%, and the breakdown field strength is increased by about 3.8%.

[0057] Table 1

[0058] Conclusion: The insulating medium prepared by the method of this application has excellent thermal conductivity and insulation properties.

[0059] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0060] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0061] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. An insulating medium, characterized in that, include: A mixed gas, comprising an insulating gas, a buffer gas, and a thermally conductive gas; Thermally conductive nanoparticles are suspended in the mixed gas.

2. The insulating medium according to claim 1, characterized in that, The volume ratio of the insulating gas, the buffer gas, the thermally conductive gas, and the thermally conductive nanoparticles is 10~25:65~85:5~10:0.1~0.

5.

3. The insulating medium according to claim 1, characterized in that, At least one of the following conditions must be met: The insulating gas includes at least one of perfluoroisobutyronitrile, perfluoropentanone, perfluorohexanone, and perfluoromethyl vinyl ether; The purity of the insulating gas is ≥99.5%.

4. The insulating medium according to claim 1, characterized in that, At least one of the following conditions must be met: The buffer gas includes at least one of carbon dioxide, nitrogen, and dry air; The purity of the buffer gas is ≥99.9%; The moisture content of the dry air is <100 ppm.

5. The insulating medium according to claim 1, characterized in that, At least one of the following conditions must be met: The heat-conducting gas includes at least one of helium, neon, argon, krypton, and xenon. The purity of the heat-conducting gas is ≥99.9%.

6. The insulating medium according to claim 1, characterized in that, At least one of the following conditions must be met: The thermally conductive nanoparticles include at least one of Al2O3 and TiO2; The particle size of the thermally conductive nanoparticles is <50nm; The thermal conductivity of the thermally conductive nanoparticles is 15 W / (m·K) to 40 W / (m·K).

7. The method for preparing the insulating medium according to any one of claims 1 to 6, characterized in that, include: The insulating gas and the buffer gas are mixed to obtain a premixed gas; The heat-conducting gas is mixed with the premixed gas to obtain a mixed gas; The insulating medium is obtained by suspending thermally conductive nanoparticles in the mixed gas.

8. The method for preparing the insulating medium according to claim 7, characterized in that, The mixing of insulating gas and buffer gas includes: The insulating gas and buffer gas are introduced into the gas distributor in descending order of liquefaction temperature for preparation.

9. The method for preparing the insulating medium according to claim 7, characterized in that, The mixing of the thermally conductive gas and the premixed gas includes: The heat-conducting gas and the premixed gas are simultaneously introduced into a gas mixer for preparation.

10. The method for preparing the insulating medium according to claim 7, characterized in that, The process of suspending the thermally conductive nanoparticles in the mixed gas includes: The thermally conductive nanoparticles are introduced into the mixed gas within 10 to 30 minutes.

11. An electrical device, characterized in that, Includes the insulating medium as described in any one of claims 1 to 6.

12. The electrical device according to claim 11, characterized in that, This includes at least one of gas-insulated switchgear, circuit breakers, instrument transformers, and switchgear.

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