Recently, composite materials with nonlinear dielectric or resistive properties performed well in electric field homogenization and space charge suppression in a high voltage transmission and distribution system. For the purpose of obtaining insulation materials with desirable dielectric and electrical resistance properties, we investigated several fillers with nonlinear electrical properties doped in silicon rubber composites, and their dependency on the temperature and field. The samples of silicone rubber composites with different components were prepared using barium strontium titanate (BST) and zinc oxide (ZnO) as the filler, and high temperature vulcanized silicone rubber (SiR) as the matrix. The investigations revealed that the BST-doped samples showed different dielectric properties compared to ZnO-doped composites, with an increase in the electric field, which was nonlinear. The resistivity of both doped samples was similar. Results demonstrated that it was possible to achieve higher values of permittivity, and lower values of tanδ and resistivity, with respect to unfilled silicone rubber composites over a wide electrical field and temperature range. Discussion of the results attributes these important functional behaviours to the spontaneous polarization of nonlinear nanoparticles and the interaction between the SiR chains and the nonlinear nanoparticles at the interfacial area.

Metal cabinets such as switch cabinets and ring network cabinets have the advantages of small footprints and good protection for equipment and offer neat and orderly protection. They are widely used in power systems. In a hot and humid environment, condensation can easily cause equipment to age and even cause insulation failure. Therefore, research on reliable anticondensation methods is of great significance for the safe operation of power equipment. In this study, phase change capsules with phase transition temperatures of 22 and 32 °C were used as fillers and liquid silicone rubber was used as a matrix to prepare liquid silicone rubber composites filled with phase change capsules for a temperature-control coating. Studies have shown that liquid silicone rubber coatings containing phase change capsules can significantly enhance the anticondensation performance of metal cabinets. By using a temperature-control coating on the surface where the cabinet experiences condensation, the temperature difference between the surface and the dew point is reduced, thereby slowing down the condensation rate and even preventing condensation.

For the purpose of obtaining desirable dielectric properties, a variety of inorganic particles fillers were doped into epoxy resin composites to change electrical behavior of epoxy resin composites. We researched electric properties of epoxy resin composites doped by nonlinear fillers, including zinc oxide(ZnO) with the size of 40nm and barium strontium titanate (BST) with the size about 100-200nm, and measured the dielectric constant (ϵ r ) and conductivity (σ). Different mass fractions (0%, 5%, 10% and 20%) of nano-sized nonlinear powder (BST and ZnO) were doped separately into epoxy composites to obtain multi-phase dielectric composites. As the electric field changed from 10 3 V/m to 10 7 V/m, electrical properties changed accordingly. The results showed that BST and ZnO fillers tended to exhibit enhanced dielectric constant and lower dielectric loss with the increase of effective mass fraction. The influence mechanism was discussed in accordance with mass fractions, electric intensity and polarization mode of each kind of nonlinear fillers.