An epoxy insulating material with high moisture resistance was prepared by grafting the hydroxyl terminated polydimethylsiloxane on o-cresol epoxy resin, and its properties were analyzed from the perspective of theoretical calculation and experiment. The results show that when the mass fraction of hydroxyl terminated polydimethylsiloxane is 10%, the modulus and toughness of the modified epoxy resin are higher, the volume change rate at high temperature is smaller. In the layer model of modified epoxy resin and water, the water molecules diffuse away from the epoxy resin. The water absorption of modified epoxy resin is decreased by 13.74% compared with the unmodified epoxy resin. After water absorption, both the volume resistivity and surface resistivity of the modified epoxy resin sample are higher than those of the unmodified epoxy resin, and its electric strength increases by 1.1 kV/mm compared with the unmodified epoxy resin.

The free acid value and PH₃ release amount of PA66 prepared by red phosphorus flame-retardant with different coating process were compared, and the morphology and contact resistance of the corresponding contact element after surface contamination were tested. The effects of housing using different red phosphorus flame-retardant PA66 on the electrical performance of AC contactor were analyzed, and the experiment of simulating the actual application environment was conducted. The results show that the red phosphorus flame-retardant PA66 using multi-layer coating process has low free acid value and PH₃ release amount, which has little effect on the electrical performance of AC contactors and can be used as one of the alternative materials for AC contactor housing.

Firstly, a natural ester was exposed to the air, and the relationships between its properties and exposure to air duration were measured. Then the oxidation situation of insulating part impregnated with natural ester in air was observed, and the natural ester on the insulating part was removed by traditional gas-phase drying method. Finally, the withstand field strength of solid insulating parts in natural ester transformer was calculated by an electric field analysis software. The results show that the water content of the natural ester increases significantly after exposure to air, but its other characteristics change little. There is no oxide film forming on the surface of insulating parts after exposed to room temperature for two months. The natural ester in insulating parts cannot be removed by gas-phase drying method completely. The withstand field strength of insulating parts in natural ester transformer is 10% higher than that in mineral oil transformer with the same structure.

The setting of boundary conditions is a key factor that affects the accuracy of stress calculation for basin insulator. In this paper, an axisymmetric model of basin insulator for miniaturized 252 kV GIS was established. The Mooney-Rivlin function model of rubber sealing ring was introduced to simulate and calculate the stress of basin insulator under different constraint boundary conditions by finite element analysis software, and the result was compared with the measured value of hydraulic test. The results show that the boundary condition using the friction contact is consistent with the engineering practice, which is suitable for the setting of stress simulation boundary condition for basin insulator. The research results can provide reference for the miniaturization and lightweight design of basin insulator of other voltage levels.

A nano organic silicone oxide sol was prepared by the hydrolysis and polymerization of methyl triethoxysilane and tetraethyl orthosilicate, which was converted into SiO₂ equivalent to mixed with polyamide-imide (PAI) resin through high-speed shearing, and then organic silicone oxide hybrid PAI composite films were prepared through film spreading and thermal curing. The composite films were characterized by infrared spectroscopy, X-ray diffraction, and SEM, and their dielectric spectra, electric strength, and corona resistance lifetime at high temperature (155℃) were tested. The results show that the nano organic silicone oxides disperse uniformly in an amorphous state in the resin matrix. With the increase of the nano organic silicone oxide content, the dielectric constant and dielectric loss factor of the hybrid PAI composite films increase gradually, the electric strength decreases gradually, and the corona resistance life increases at first and then decreases. When the mass fraction of the nano organic silicon oxide is 15% of SiO₂ equivalent, the corona resistance life of the hybrid PAI composite film at high temperature is 3.1 times longer than that of pure PAI film.

On the basis of radiation spectral characteristics of insulation abnormal discharges, a dual-spectral discharge detection method was proposed. The differences of spectral distribution characteristics under corona discharge, spark discharge, and arc discharge were obtained through experiments, and a dual-spectral sensor based on solid avalanche array was developed. The evolutional relationship between the dual-spectral characteristics and discharge energy was studied using this sensor, and then the discharge hazard quantification criteria based on dual-spectral intensity ratio was summarized. The results show that the light radiation under three kinds of discharge modes has a certain polarity effect. There is a strong correlation between the dual-spectral intensity ratio and the discharge intensity, and there is almost no intersection for the variation range of dual-spectral ratio of low-energy discharge and high-energy discharge, which can be used as an effective criterion to judge partial discharge or arc discharge, and provide a new approach for the optical monitoring and diagnosis of abnormal discharges in equipment.

A aluminum thin-walled cylinder was used to replace the cable to finish the actual setting process of terminal. The interface pressure between the 110 kV prefabricated cable terminal and the stress cone was measured by the electrical measurement method and elastic mechanics theory. By finite element simulation analysis and comparing the calculating result and test result, a reasonable finite element simulation analysis model was established and the terminal setting process was simulated. Several analysis models with different interference were established to study the influence of interference, silicone rubber material parameter, and spring compression on the interface pressure. The results show that the maximum interface pressure is located in the middle of the maximum radius of stress cone. The interface pressure is proportional to the spring compression before the spring compressing to 90 mm, and the interface pressure changes little during the process of the spring compressing from 90 mm to 85 mm. The interfacial pressure is affected by the interference and the cross-sectional area of cable, and it is greatly affected by the elastic modulus of stress cone, and less affected by the elastic modulus of cross-linked polyethylene (XLPE) insulation.

In order to study the ablation mechanism of buffer layer in cable, we analyzed the change of contact state between buffer layer and aluminum sheath according to the defect phenomenon, and then a circuit model was established to analyze the defect. According to the model, the induced voltage of insulation shielding layer and the main factors affecting the induced voltage were analyzed. A 15 m defective cable sample was intercepted from the breakdown accident line, and a partial discharge detection experimental platform was built with the defective cable sample. The results show that the induced voltage of insulation shielding layer is directly proportional to the number of defects, the resistivity of composite layer, and the thickness of white powder at the defect, and is inversely proportional to the contact area between buffer layer and aluminum sheath, and the discharge signals inside the defect cable have obvious characteristics of poor contact discharge.

A barium titanate/polyvinylidene fluoride (BT/PVDF) composites was prepared by solution blending method, and the effect of size distribution and content of BT particles on the dielectric properties, electric strength, energy storage properties, and thermal stability of the composites were investigated. The results show that compared with single particle size BT, the synergistic effect of double particle size BT filler makes the composites have more excellent comprehensive properties, and the synergistic effect is the most remarkable when the mass ratio of BT with double size is equal to 1. With the increase of filler content, the dielectric constant and thermal stability of the composites increase, and the dielectric loss factor of the composites maintains at the relative low level. When the mass fraction of BT is 60%, and the mass ratio of BT with double size is 5∶5, the dielectric constant of BT/PVDF composites reaches 46.5 at 100 Hz, which is 5 times bigger than that of pure PVDF; the energy storage density and polarization are 0.18 J/cm³ and 0.011 9 C/m², respectively, which are 176% and 310% higher than those of pure PVDF; the decomposition temperature corresponding to 5% of weight loss reaches 478.4℃, which is 1.3℃ and 30.3℃ higher than that of PVDF composites filled with S-BT and L-BT, respectively.

In order to study the ablation mechanism of buffer layer of corrugation aluminum (Al) sheath high voltage cross-linked polyethylene (XLPE), firstly, we analyzed a ablation failure of 110 kV XLPE insulated cable, and proposed that the concentrated radial current was the cause of ablation failure. Secondly, a simulation model of the faulty cable was established. The current density and its distribution of the contact part of buffer layer and corrugated Al sheath were simulated, and the simulation results were proved by model experiment and calculation. It was found that the size and distribution of radial current were affected by the embedded depth of Al sheath in the buffer layer and the volume resistivity of the buffer layer. Finally, simulation experiments were designed to prove that the radial current concentrated was one of the causes of buffer layer ablation, and the experimental conditions of the simulated ablation experiment were controlled in the thermostat. The surface morphology of the experimental sample and the ablated Al sheath were compared by optical microscope. The results show that the ablation process in the ablation experiment is the same as that in the actual faulty cable, and with the increase of the current density in buffer layer, the ablation start time decreases. This paper reveals the physical mechanism of radial current concentration in the ablation fault of corrugated Al sheath, which provides guideline for relevant fault diagnosis and protection.