Investigation of electrical field grading of bushings with microvaristor filled epoxy resin components

High electric field intensities along the composite insulator surface of high voltage bushings, in particular around the area of the grounded electrode, can result in electrical partial discharges on the silicone rubber surface. The microvaristor filled epoxy resin components are applied to bushings in order to reduce the electric field intensity locally. Using this nonlinear component makes it possible to reduce the diameter of bushings, while still having a reasonable electric field distribution. This new compact design is analyzed using numerical simulations. The corresponding prototypes are experimentally tested in the high voltage laboratory.