Electric Field Stress in a Three Phase Common Enclosure Gas Insulated Busduct with FGM Post Type Spacer and Reduction with Metal Inserts

The establishment of supporting insulators plays a vital role in the continuous operation of the three-phase Gas Insulated Busduct (GIB), which primarily depends on the distribution of electric field stress on the spacer surface. Shape control is a technique used along the spacer surface to achieve uniform field intensity, but this technique can also lead to very irregular shapes. The Triple Junction (TJ) is the region where the field stress has to be reduced. Over a period, high field stresses along the spacer surface will result in a surface flashover and thus de-energize the complete GIB, leading to enormous losses economically. In this paper, a Functionally Graded Material (FGM) spacer for a three-phase GIB has been designed with more number of gradings and further field stress at TJ is minimized by inserting and reshaping the metal inserts (MI) at the end of the enclosure. By doping them with different permittivity values, functionally graded materials are spatially distributed with multiple filler materials to achieve uniform stress on the electric field. Simulation is carried out with the FGM and epoxy (post type) Spacers for different voltages and FGM gradings. With MI, the stress is minimized and an enhanced uniform field allocation along the surface is obtained.