Development of Cone-Type FGM Spacer for Actual Size GIS

Functionally Graded Materials (FGM) with spatial distribution of dielectric permittivity (ε
r
) have been expected and investigated as a novel electric field grading material for high voltage power apparatus. This paper discusses the development of cone-type FGM spacers for 245 kV -class gas insulated switchgears (GIS). The FGM spacers with ε
r
between 10 and 4 using SrTiO
3
and SiO
2
fillers were fabricated by flexible mixture casting method, and their breakdown voltages were measured for different SF
6
gas pressures under lightning impulse voltage. The breakdown voltage of FGM spacer in pressurized SF
6
gas was expected to be 25 % higher than that of conventional spacer with a constant permittivity distribution.