Fabrication of Permittivity Graded Materials ( $\varepsilon$ -FGM) by Flexible Mixture Casting Method

For the downsizing of gas insulated power apparatus, we have proposed the electric field grading technique by “functionally graded materials” with spatial distribution of permittivity ( $\varepsilon$ -FGM). In this paper, we fabricated post-type and truncated cone-type $\varepsilon$ -FGM by a novel and practical technique “flexible mixture casting method” (FMC method). We confirmed that $\varepsilon$ -FGM by FMC method has the discharge inception voltage improvement effect by both experiment and simulation.