Optimal design of an elliptically graded permittivity spacer configuration in gas insulated switchgear

A functionally graded material (FGM) was investigated for use as an insulator in high voltage applications. The FGM was able to relax the electric field concentration around a high voltage electrode and along the gas-insulator surface. The FGM spacer, the permittivity of which was gradually changed, exhibited a considerable reduction in the maximum electric field when compared to a conventional spacer with a uniform permittivity. It is difficult to apply a gradual permittivity variation in the FGM spacer to real product processing due to its complicated shape. Thus, in this work, the electrode shape in the gas insulated switchgear was changed in order to increase the possibility of real FGM insulator manufacturing. To achieve this goal, optimization processes were used to modify the shape of both the electrode and the FGM spacer on a commercial gas insulated switchgear configuration. Especially, a modification of the spacer configuration was performed with the design of experiments (DOE). Consequently, the insulation capability of the switchgear with the optimally designed FGM spacer can be efficiently improved.