Fabrication and experimental verification of permittivity graded solid spacer for GIS

Functionally gradient materials (FGM) have a spatial distribution of permittivity in order to achieve an efficient stress control. The application of FGM to solid spacers for gas insulated switchgear (GIS) is expected to improve electric field distribution around the spacer. In this paper, we discussed the applicability of FGM with experimental results and fabrication conditions. We firstly investigated the field control effect of the double-layer distribution FGM spacer by dielectric breakdown experiments under the application of lightning impulse voltage. Secondly, we confirmed the effect of FGM on the enhancement of electric field utilization experimentally. Thirdly, we succeeded in the fabrication of continuously graded distribution of permittivity by applying the centrifugal force technique.