No abstract

We have been investigating functionally graded materials (FGM) with the purpose of controlling and relaxing electric field in solid insulator of electric power apparatus. FGM is characterized by the spatial distribution of dielectric permittivity in a solid insulator, and can control the surrounding electric field distribution in power apparatus such as gas insulated switchgears (GIS) and epoxy mold transformers. In this paper, we fabricated a coaxial disk-type GLP (grading to lower permittivity)-FGM for the GIS spacer. Experimental results revealed that we could fabricate GLP-FGM with relative permittivity distribution from 8.2 to 5.3 in the coaxial disk-type spacer. According to the numerical analysis, the maximum electric field at the HV-electrode/spacer interface was reduced by 12 % for the coaxial disk-type GLP-FGM than that of the conventional spacer with uniform permittivity.