Optimizing the microstructure of alumina as substitute to polymer insulation for large‐capacity power transmission

Abstract Polymer insulation has encountered great challenge due to the increasing electrical–thermal stresses in power apparatus with high voltage and large capacity, while ceramic dielectrics are potential to substitute polymer for better long‐term reliability. However, the internal insulation issue in the apparatus is rather different with traditional vacuum insulation and the overall insulation performances of current ceramic dielectrics are not satisfied enough to be directly applied in power apparatus. This paper has proposed a method to comprehensively improve the insulation performance along the gas–solid interface for alumina based ceramic through microstructure modulation. The influencing mechanism of microstructure on the dielectric properties, including the volume resistivity and its temperature‐dependent behavior, the charge accumulation and the flashover voltage along the gas–solid interface of alumina are revealed. On this basis, optimized formula of alumina ceramics with excellent comprehensive insulation properties are acquired which shows great advantage over current polymer insulation.