Breakdown Characteristics of Cone-type ε-FGM Spacer for Gas Insulated Switchgears

For the downsizing of gas insulated switchgears (GIS), a novel electric field grading technique is highly expected. In order to meet this demand, we have been investigating the electric field control and relaxation technique by “functionally graded materials” with the spatial distribution of permittivity (ε-FGM). In this paper, we fabricated the 1/4-sized cone-type ε-FGM spacer for 245 kV-class GIS and verified its breakdown voltage improvement effect by both experiment and simulation.