Effects of Different Defects on the Electric Field Distribution of Insulation Rod for GIS

Insulation rods made of fiber-reinforced composites are key components in gas-insulated switchgear (GIS). Micro defects are prone to be introduced inside the rod during manufacture. Effects of defects with different type and size on the electric field distribution within the insulation rod are investigated. A numerical simulation model is established firstly and various defects are introduced into the model. Obtained results show that the electric field strength decreases from high voltage terminal to ground along axial direction. Different defects will distort both surface and internal electric field with varying degrees. As for gas void defects, the degree of electric field distortion along rod surface and through the defect is comparable. However, the impact of delamination defect on the internal electric field is far greater than that on the rod surface. It is suggested that defects near high voltage terminal during opening and closing situations need to be carefully checked before use, considering the maximum electric field will migrates along the axis because partial rod structure will move into the shielding when the breaker is closing.