A numerical approach for analysis of structure of voltage-endurance nanoporous-silica composite insulator

This paper presents an attempt to show the effectiveness of nanoporous-silica composite in epoxy matrix for voltage-endurance and lower permittivity by numerical analysis. By finite element analysis of the static electric field, we estimated the permittivity of the nanoporous-silica composite insulator required to reduce the electric field enhancement around the GIS solid spacer. In order to achieve the effective lower permittivity of nanoporous-silica composite insulator, we estimated the amount of nanopore volume by using the random arranged model for dielectric mixtures. The electric field inside nanopore of the nanoporous composite insulator can be also intensified due to the difference in permittivity among air, epoxy and silica, which may lead to the void discharge. Depending on the nanopore size, the nanopore might be a critical defect for voltage-endurance. Based on the Paschen´s law, we estimated the nanopore size required not to allow the void discharge in nanopores. Finally, the nanoporous-silica structure of nanoporous composite required to achieve both lower permittivity and high dielectric strength is discussed.