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.

In this paper, the research process of alicyclic polyimides (Al-PIs) at home and abroad in recent years was reviewed, and the synthesis of typical monomers and polymers were described from the historical evolution perspective mainly. The applications of alicyclic polyimides in transparent flexible display, gas separation membrane, photosensitive material, and liquid crystal orientation membrane were discussed, and the development trend and application prospect of alicyclic polyimides were prospected.

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.

Three kinds of organic ultraviolet absorbers with the same concentration were added to polyethylene terephthalate (PET) films, and the properties of PET films before and after UV ageing were tested, and then the effects of ultraviolet absorbers on the UV ageing properties of PET films were studied. The results show that the UV ageing properties of PET films are related to the structure of ultraviolet absorber. Compared with triazine and benzotriazole ultraviolet absorbers, oxazinone ultraviolet absorber exhibits red shift of UV absorption wavelength, wider UV absorption range, and stronger UV absorption intensity because of its hyperconjugated structure. With the increase of ultraviolet radiation energy, the mechanical properties and glossiness of the three kinds of UV resistant transparent films decrease gradually, and the yellow index increases gradually. When the ultraviolet radiation energy is higher than 120 kWh/m², the property differences of the three kinds of UV resistant transparent films before and after ageing are obvious. The property difference of the film containing oxazinone hyperconjugated structure ultraviolet absorber before and after UV ageing is the smallest, and the ageing resistance is the best.

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.

This paper summarized the global patent layout of corona resistant PI films, the influencing factors of corona resistance for inorganic nano hybrid films, and introduced the application status of corona resistant PI films at liquid nitrogen temperature, as well as the future development of corona resistant PI films.

Mechanical impact is an important factor that damages the stator bar insulation material. At present, systematic researches on the damage of stator bar insulation materials by mechanical impact are still lack. In this paper, the effect of mechanical impact on the stator bar insulation material was studied by combining the finite element simulation and experiment. The results show that when the insulating material is subject to mechanical impact, the average equivalent stress-strain and electric strength firstly increase or decrease, and then become stable within a certain impact strength range under the same punch structure. Under the same impact strength, both the average equivalent stress-strain and electric strength increase with the increase of the tip area of punch head. The correlation between the average equivalent stress-strain and the electric strength can be used to evaluate the insulation damage of stator bar caused by mechanical impact.

Compared with mineral oil transformer, vegetable oil transformer has the characteristics of strong overload capacity, high fire safety, and good environmental performance. At the same time, its noise generated during operation is smaller than that of dry-type transformer, and the loss is lower, the size is smaller, the price is lower. So more and more power grid and industrial users began to use vegetable oil transformer. The current research progress of vegetable oil transformer from the aspects of design, material application and research, production and operation maintenance was summarized in this paper, and the research direction and prospect of vegetable oil transformer were prospected.