Feasibility study on FGM (functionally graded materials) application for gas insulated equipment [solid insulators]

For size reduction of electric power equipment, the electric field stress around solid insulators is to be increased and must be carefully considered. This concern may be solved by the application of FGM (functionally graded materials). We investigated an application feasibility of FGM, from both an experimental approach and numerical simulation, and the fabrication technique for gas insulated equipment. Firstly, we investigated the fabrication techniques for the continuously graded permittivity distribution with an arbitrary direction and gradings. As a result, we established fabrication techniques for the grading of permittivity distribution in a higher or lower direction by centrifugal force application. Next, we fabricated a truncated cone FGM spacer, and carried out dielectric breakdown experiments under lightning impulse voltage application. Finally, we could confirm the significant effect of FGM application for gas insulated equipment.