Application of Non-Linear Discrete Spatial Permittivity Distributions in Reducing Electric Field Concentration in GIS Spacer

This research is focused on investigating the application of electric field grading method of functionally graded material (FGM) on a GIS spacer can reduce the maximum electric field intensity around the GIS triple junction area. To realize this purpose, FGM spacers in this study is using a fabricated discrete technique (stepwise layers). This study uses a spatial distribution model of discrete permittivity ($\varepsilon_{\mathbf{r}}$) of 5 layers with a value of 3.5 to 7.5. The composite filler that is mixed into the Epoxy Resin is TiO$_{\mathbf{2}}$ particles with high permittivity and SiO$_{\mathbf{2}}$ particles with low permittivity. The graded permittivity distribution is expected to allow effective in control the maximum of electric field strength along the surface of the spacer, especially in the triple junction (TJ) area as the weakest pant of the GIS insulation. From the electric field simulation results, it is obtained that permittivity distribution of the U-shape can reduce the electric field intensity around the high voltage triple junction (TJ-HV) area from 399.90 kV/m to 251.34 kV/m with 37% reduction. The large to small permittivity distribution (BS-FGM) can reduce the electric field intensity from 399.90 kV/m to 249.38 kV/m, with 38% the electric field. The final results of this study shows that fabricating spacer with permittivity distribution of Ushape, filler loading weight of 30% is used for the middle layer of the spacer, while part near the TJ-HV and TJ-GND sections, a filler loading weight of 40% is used vs the total weight of the epoxy resin matrix.