Thick-film heating has become a key thermal-management solution for new-energy vehicles. To meet the relevant application demands, it is necessary to develop dielectric slurries for aluminum-based thick-film heating elements. This study utilized the built-in machine learning model of the Inorganic Glass Engineer System for property prediction to assist in the development of dielectric insulating glass formulations for aluminum-based thick-film heating elements, and conducted experimental verification. The results show that the insulating glass prepared by the optimal formula can be sintered at 580℃, with a thermal expansion coefficient of 18.8×10^-⁶℃^-1. When the dielectric-layer thickness exceeds 110 μm, it has a breakdown voltage over 1.29 kV and a leakage current less than 0.21 mA, which can meet the usage requirements of the medium layer of aluminum-based thick-film heating elements.

The interfacial characteristic between the shielding layer and insulation layer is a key factor determining the service life and operational reliability of the high-voltage cables. This study focused on the regulation of the dispersion of conductive carbon black (CB), and investigated the impact of interfacial characteristics between the shielding layer and cross-linked polyethylene (XLPE) insulation layer. The semi-conductive shielding materials with two different formulations were prepared, and an imported semi-conductive shielding material was selected as a comparison sample, then the mechanical, thermal, and electrical compatibility between the shielding materials and insulation layer were comprehensively evaluated. The results show that the introduction of polymer dispersant polyvinylpyrrolidone (PVP) into the matrix resin significantly improves the dispersibility of CB. The mechanical compatibility between the shielding layer and insulation layer is predominantly influenced by crosslinking, and an optimal crosslinking compatibility can enhance the interfacial adhesion and prevent delamination. The PVP-modified shielding layers exhibit better thermal compatibility with the insulation layer in terms of the coefficient of thermal expansion, and show superior thermal conductivity compared to the imported shielding material. Furthermore, the improved CB dispersion optimizes electrical compatibility between shielding layer and insulation layer, elevating the AC electrical strength at the shield-insulation interface.

To solve the ageing problem of transformer insulation oil after the long-term operation, three composite materials, including glucose attapulgite (GLU-APT), starch attapulgite (AL-APT), and polydopamine attapulgite (PDA-APT), were designed and prepared. The structures of the composite materials were characterized by X-ray diffractor, field emission scanning electron microscopy, Raman spectrometer, Fourier transform infrared spectrometer, and N₂ adsorption-desorption test. The results show that the decolorization and acid value reduction effects of the three composite materials on retired oil improves significantly compared to APT, among which the GLU-APT shows the best regeneration effect to retired oil. When the mass ratio of GLU-APT adsorbent and retired transformer oil is 1:2, the adsorption time is 2 h, and the adsorption temperature is 90℃, the decolorization rate of regenerated oil can reach 88.2%, and the acid value is reduced to 0.010 mgKOH/g, the adsorption efficiency can maintain 90% after 5 cycles of regeneration.

Room temperature vulcanized silicone rubber (RTV-SiR) is an important polymer coating material for high voltage insulators. The ageing behavior of RTV-SiR under long-term exposure to environmental stimuli is an essential consideration for its field applications. In this study, composite coatings were prepared by incorporating nanometer-scale silicon dioxide (SiO₂) and aluminum trihydrate (ATH) into RTV-SiR. Then the composite coating samples were conducted accelerated ageing for 9 000 h, and their micro-morphology, hydrophobicity class (HC), leakage current, Fourier transform infrared spectroscopy (FTIR), electrical strength, and mechanical strength were tested to investigate the ageing characteristics of SiO₂/ATH-filled RTV-SiR. The results show that the addition of SiO₂ and ATH fillers to RTV-SiR enhances the anti-degradation capability and environmental stress resistance of the composite coatings during ageing, preserving the samples' hydrophobicity. After ageing, compared with RTV-SiR, the composite samples exhibit a relatively smaller increase in leakage current and maintain higher electrical strength. According to FTIR analysis, the loss rates of several important absorption peak intensities of RTV-SiR are higher during ageing, and almost none of them can be restored, whereas those of the samples filled with SiO₂/ATH demonstrate a loss-recovery characteristics. Additionally, compared with RTV-SiR, the SiO₂/ATH-filled samples exhibit significantly lower reductions in tensile strength, elongation at break, and hardness after ageing treatment, indicating superior ageing resistance.

In order to suppress surface charge accumulation on the insulation in HVDC wall bushings and improve their flashover performance, the epoxy resins used for the supporting insulator and the tube body were surface fluorinated under the same conditions using a fluorine/nitrogen mixture. The results show that fluorine atoms are introduced into the surface layers of two types of epoxy resins by the substitution for hydrogen atoms and the addition to carbon-carbon double bonds, forming C-F bonds. The fluorination is accompanied by chain breaking, which mainly occurs at the crosslinking sites. Due to the difference in epoxy value, two types of epoxy resins show different crosslinking densities. SEM imaging shows that they have different thicknesses of the fluorinated layer and surface morphologies. Surface potential decay and surface conductivity measurements reveal that the fluorination increases surface conductivity of two types of epoxy resins and inhibits their surface charge accumulation to different degrees. Flashover tests show that their DC flashover voltages are significantly increased by the fluorination to almost the same degree.

The temperature rise characteristics of gas-insulated transmission lines (GIL) determine their current-carrying capacity. To investigate the temperature rise characteristics of two typical environmental friendly insulating gases — perfluoroisobutyronitrile (C₄F₇N) mixed gas and dry air, the temperature rise process of a 126 kV three-phase common-tank GIL was simulated, and based on the simulation results, a temperature rise test platform was established. Then the temperature rise tests were carried out under conditions such as different gas dielectrics and current magnitudes. The results show that under the identical current conditions, the temperature rises of both C₄F₇N/CO₂ mixed gas and dry air under typical application parameters are similar, yet both exceed that of SF₆ gas. When the current loading is 3 150 A, both C₄F₇N/CO₂ mixed gas-filled and dry air-filled equipment can meet the requirement of temperature rise not exceeding 75 K, but when the current loading is 3 465 A, neither filling with C₄F₇N/CO₂ mixed gas nor filling with dry air can satisfy this requirement. It is also found that when the three gases were filled respectively, the temperature rise of phase B is higher than that of phase A and phase C, aligning with simulation results and thermal convection processes, indicating that the maximum temperature rise of phase B conductors requires special consideration in the temperature rise design of 126 kV three-phase common-tank GIL.

To investigate the thermal ageing mechanism of dry air core reactor encapsulated insulating materials at the molecular level, this study conducted 336-hour accelerated thermal ageing tests on epoxy/glass fiber composites at 180℃. The evolutionary characteristics of functional groups, molecular chain segment motions, activation energies, and AC electric strength of the epoxy/glass fiber composites after ageing were characterized by infrared spectroscopy, dielectric spectroscopy, and AC electric strength test. The effect of the decrease in activation energy caused by the changes in chemical structure and the evolution of molecular chain segment movement properties during ageing on the AC electric strength was investigated. The results show that a lot of carbonyl groups and small molecular chains dominated by ester and ketone groups generate during the ageing process. These small molecule chains and polar groups greatly increase the free volume and the number of free electrons inside the epoxy matrix, so that the chain segment movement is gradually enhanced and the activation energy is reduced, which ultimately leads to a significant reduction in insulation capacity.

Using styrene-butadiene-styrene (SBS) as the resin matrix and SiO₂ as the filler, SiO₂/hydrocarbon high frequency hydrocarbon copper clad laminate with low dielectric loss were prepared by hot-pressing method using a double-roll open mill and a flat vulcanizing machine. The resin film forming method and the influence of different contents and morphologies of SiO₂ under the open mill film on the dielectric performance, peel strength, thermal conductivity, tensile performance, and water absorption rate of high frequency hydrocarbon copper clad laminate were explored. The results show that compared with the traditional solvent-based resin film method, the solvent-free film production using an open mill has obvious advantages in the molding of composite resins and material properties. With the increase of SiO₂ content, the dielectric constant and dielectric loss of the high frequency hydrocarbon copper clad laminate increase, while the peel strength and water absorption rate decrease. Under the same particle size and filling content of SiO₂, the dielectric constant, dielectric loss factor, and water absorption rate of spherical SiO₂/hydrocarbon high frequency hydrocarbon copper clad laminate are lower than those of angular SiO₂/hydrocarbon high frequency hydrocarbon copper clad laminate. When the mass fraction of spherical SiO₂ is 75%, the comprehensive performance of the carbon-hydrogen high-frequency board is relatively superior, with a dielectric constant lower than 3.3, a dielectric loss factor of 0.002 2, and a water absorption rate lower than 0.040%.

To investigate the rejuvenation effect and enhancement mechanism of the voltage stabilizer-containing rejuvenation fluid on moisture-affected XLPE/SiR interface, XLPE was sanded by sandpapers with different granularities to prepare XLPE/SiR interface samples. At first, the surface roughness of the samples was measured using a profilometer, and interfacial breakdown tests were conducted. Then, the samples were subjected to moisture tests. After that, the antioxidant 300 and ferrocene were selected as voltage stabilizers, and five rejuvenation fluids with different stabilizer content were prepared to rejuvenate the moisture-affected interfaces. The interface samples before and after rejuvenation were further analyzed by surface profilometry, Fourier transform infrared spectroscopy (FTIR), polarization-depolarization current (PDC), and interface breakdown tests. The results show that the interfacial breakdown voltage decreases with the increase of surface roughness, while the moisture exposure elevates the interfacial DC conductivity and dielectric loss factor and decreases the interfacial breakdown voltage. After the rejuvenation, the interface roughness, DC conductivity, and dielectric loss factor of the samples decrease, and the rejuvenated product can homogenize the electric field distribution between the cavity and the solid dielectrics, and significantly increase the interfacial breakdown voltage. Moreover, the addition of antioxidant 300 and ferrocene can enhance the interfacial breakdown voltage, and ferrocene has a better improvement effect on the insulation performance of the moisture-exposed interface.

In this paper, different types of polyurethane potting materials were developed successfully by taking propylene epoxide-tetrahydrofuran polyether or polytetrahydrofurane glycol as polymer polyols, toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), and 3,3′-dimethyl-4,4′-biphenyl diisocyanate (TODI) as curing agents, and adding an appropriate amount of silica aerogel. The mechanical property, proccessability, low temperature resisitance, high temperature resistance, resistance to high and low temperature shock, and insulting property of the polyurethane potting materials were analyzed systematically. The results show that the polyurethane potting material formulated with propylene oxide-tetrahydrofuran copolymer and TODI as primary components, supplemented with silica aerogel with the mass fraction of 0.5%, exhibits outstanding processability, mechanical strength, and electrical insulation. It also demonstrates exceptional tolerance to extreme temperature fluctuations. This material achieves a glass transition temperature as low as -69.3°C and maintains a compression cold resistance coefficient of 0.54 at -60°C. Its 5% weight loss temperature reaches 302.3°C. After enduring 20 cycles of thermal shock between -65°C and 125°C, the material retains 93.5% of its tensile strength with a dimensional change rate of merely -0.6%, while preserving excellent insulation properties: volume resistivity of 4.2×10¹² Ω·cm and dielectric strength of 25 kV/mm.