In order to analyze the effects of rutile nano-TiO₂ doping on the properties of polyethylene (PE) materials from the microscopic perspective, PE and TiO₂/PE composite models with different mass fractions of water molecular were constructed by using molecular dynamics simulation method. And then taking temperature as a variable, the thermodynamic properties and microstructure of PE before and after being modified by nano-TiO₂ and the diffusion ability of water molecules in the composite system were analyzed. The results show that after doping with nano-TiO₂, the glass transition temperature of PE system increases by 33 K, the Young's modulus increases by 428.17%, and the shear modulus increases by 338.62%. Nano-TiO₂ greatly inhibits the movement of PE molecular chain and the diffusion of water molecules, which increases the stability of the composite system. The addition of water molecular and the increase of temperature decrease the thermodynamic properties of the composite system, both of which destroy the stability of the composite system.

In the preparation of tetragonal nano-barium titanate powder by traditional solid-phase method, the dispersion and particle size of the BaCO₃ precursors play a crucial role in the morphology, particle size, and dielectric properties of the obtained tetragonal BaTiO₃ nanoparticles. In this paper, nano BaCO₃ powders were prepared by controlling the concentration of the Ba(OH)₂ using Ba(OH)₂ and drikold as raw materials. Then, BaTiO₃ powders and ceramic were prepared using the BaCO₃ powders, and the dielectric properties of BaTiO₃ ceramic was studied. The results show that the short rod-shaped nano BaCO₃ powders with a particle size of 180 nm and the highly dispersed, highly uniform and pure tetragonal BaTiO₃ powders with a particle size of 400 nm were prepared. The dielectric constant and dielectric loss factor of the BaTiO₃ ceramic obtained by calcination at 1 250℃ is 4 885 and 0.018 9, respectively.

In this study, EPDM seal ring commonly used in gas insulated switchgear (GIS) equipment was treated at -55℃, and the effects of low temperature on its surface morphology, structure, glass transition temperature, and mechanical properties (tensile and compression permanent deformation) were investigated. The results show that the low temperature treatment cannot damage the macromolecular chain structure in the seal ring, but it is easy to cause frosting, and the glass transition temperature shows an increasing trend. The mechanical properties of the seal ring change greatly after low temperature treatment, the hardness and breaking strength decrease, while the elongation at break and compression permanent deformation increase. The degree of change in tensile property is related to the amplitude of alternating temperature difference in alpine environment, the greater the amplitude, the greater the breaking strength loss of the seal ring.

Simulation calculations were conducted on the stator bars and windings of generator in a high altitude area by establishing a simulation model, and the rationality of the anti-corona design of the stator bar and winding was explored. According to the design, the stator bars and windings were manufactured and the reliability of the anti-corona structure was further verified through experiments. The simulation calculation results show that when the altitude is 3 000 m, the maximum field strength of the stator bar during the operation voltage, anti-corona assessment voltage, and voltage withstand process is 0.32, 0.44, and 0.53 kV/mm, respectively, and the maximum loss is 2.19×10⁵, 1.46×10⁶, and 6.34×10⁶ W/m³, respectively. The maximum electronic density between the layers of the generator winding is 1.32×10¹⁷ m^-3. After the modification of the oblique clearance of the stator winding, the maximum field strength of the stator bar during the operation voltage, anti-corona assessment voltage, and voltage withstand process is 0.78, 1.50, and 2.14 kV/mm, respectively, and the maximum loss is 3.01×10⁵, 6.8×10⁵, and 3.23×10⁶ W/m³, respectively. The experimental results show that the stator bars can pass the corona test under 40.7 kV and the withstand voltage test under 73.5 kV for 1 minute. With the increase of altitude, the ultraviolet photon number of the winding at 1.1U_n increases gradually, while that number is less than 1 000 when the altitude is below 3500 m. The anti-corona performance of the designed winding meets the design and operation requirements of the unit.

With a high voltage grade and large transmission capacity, ultra-high voltage (UHV) gas insulated metal enclosed transmission line (GIL) needs insulator with higher resistance to the comprehensive effect from electric, heat, and force. In this paper, epoxy composite materials were prepared by doping micro-Al₂O₃, micro-SiO₂, and micro-Al₂O₃-SiO₂ blend fillers, respectively. The mechanical, thermal, and electrical properties of the blend system were tested and analyzed. The results show that with the increase of the volume proportion of Al₂O₃, the comprehensive mechanical properties of the composites are improved, and pure micro-Al₂O₃/epoxy composite exhibits the best mechanical properties. Doping two fillers improves the thermal conductivity and arc resistance of the composites, but slightly reduces the glass transition temperature and increases the thermal expansion coefficient. When the volume ratio of Al₂O₃ and SiO₂ in composites is 1:1, the arc resistance duration and the thermal conductivity of the composite reaches 1.198 W/(m·K） and 186.63 s, respectively. With the increase of the volume proportion of SiO₂, the dielectric constant of the composites decreases, while the breakdown strength increases. The power frequency breakdown strength of the pure micro-SiO₂/epoxy composites is the highest, reaching 36.63 kV/mm.

In this paper, the characteristics of high-frequency copper clad laminates were summarized, the dielectric properties of their base resins were compared, and the research progresses of hydrocarbon resin (PCH) high-frequency copper clad laminates were mainly introduced. By summarizing the current researches on hydrocarbon resin based high-frequency copper clad laminates, the existing problems were pointed out, and their future development trends were prospected.

Electron irradiation in the Geosynchronous orbit (GEO) will cause charge accumulation in aerospace insulating materials, which may cause electrostatic discharge of dielectric, while the electrostatic discharge will also affect the charge accumulation. In this paper, the joint measurement experiment of potential distribution and electrostatic discharge current was carried out on polyimide film materials under electron irradiation, and the surface charging and discharging process of polyimide film materials under the electronic irradiation of harsh GEO environment were studied. The results show that the surface potential of polyimide film is negative polarity under the electronic environment of 15 keV, 0.33 nA/cm², the distribution patterns include unimodal type, multimodal type, crater type, and flat top type, and the unimodal type and multimodal type have the highest discharge number. Short-term multiple discharges will change the potential distribution pattern and make the transformed distribution pattern maintain for a long time. The potential distribution pattern will affect the wavefront time of discharge current signal, while the potential level will affect the half peak time of discharge current signal, and the half peak time of the current signal at low potential level is about 28% higher than that at high potential level.

In this paper, a multi-source partial discharge diagnosis method based on joint detection of pulse current method and ultraviolet pulse method was presented. A multi-source partial discharge experimental platform of switchgear was constructed for four basic defect models. The characteristics of partial discharge information obtained by joint detection were extracted and a database was constructed, and then the discharge types were identified by k-nearest neighbor (KNN) algorithm and directed acyclic graph SVMs (DAG-SVMs) algorithm. The results show that the change of discharge number and discharge quantity in discharge pattern measured by pulse current method are related to the defect type in model. The existence of void and surface defects will increase the discharge quantity and pattern symmetry, and the existence of corona defect will increase the discharge number. The discharge pulse number measured by ultraviolet pulse method is related to the defect number in multisource discharge model and the ratio of ultraviolet to visible light. The higher the number of defects and the ratio of ultraviolet to visible light, the larger the discharge pulse number. The recognition accuracy of the KNN algorithm can reach up to 99.67%.

Multilayer ternary composite polypropylene (PP) films with different content of nano-ZrO₂ particles were prepared with a ternary composite PP film constructed by maleic anhydride grafted PP and nano-ZrO₂ particles as the outer layer and neat PP film as the middle layer, and their physical and chemical properties as well as electrical properties were measured. The results show that the nano-ZrO₂ exhibit good dispersibility in ternary composite PP system and there is a distinct interface between ternary composite PP film and neat PP film. The crystallinity of multilayer ternary composite PP films is higher than that of the single layer neat PP film. With the increase of nano-ZrO₂ content, the dielectric constant of the multilayer ternary composite PP film increases, while the DC electric strength increases at first and then decreases. When the mass fraction of nano-ZrO₂ reaches 1.0%, both the DC electric strength and energy storage density achieve the highest value (424.3 kV/mm and 2.14 J/cm³), which are about 10.6% and 31.3% higher than those of the single layer neat PP film. Besides, the dielectric loss factor of multilayer ternary composite PP film remains at the same level of 10^-3 as that of neat PP film. The ternary composite PP and interlayer interface can jointly suppress the migration of heteropolar space charges, which contributes to improve the internal electric field distribution of dielectric, increase the electric strength, and reduce the dielectric loss caused by electron migration.

A series of HFBAPP/6FDA/BPADA fluorinated phenyl ether-containing polyimide films were prepared using 2,2-bis [4-(4-aminophenoxy)phenyl] hexafluoropropane (HFBAPP) as the diamine monomer, 2,2′-bis (3,4-dicarboxylic acid) hexafluoropropane dianhydride (6FDA) and bisphenol A-type diether dianhydride (BPADA) as the dianhydride monomer. The effects of ether bond and trifluoromethyl on the comprehensive performance of polyimide films were analyzed and compared by changing the ratio of dianhydride monomer. The results show that with the increase of trifluoromethyl content and the decrease of ether bond content, the optical and thermal properties of the HFBAPP/6FDA/BPADA fluorophenyl ether-containing polyimide films increase, while the mechanical properties decrease, the glass transition temperature can reach 247.3℃, the residual carbon rate at 800℃ can reach 56.3%, the maximum transmittance in the visible range is 88.2%, and the maximum tensile strength is 84.7 MPa.