Performance Assessment of FRP Rods of 400 kV Field-Aged Composite Insulators

The satisfactory performance of silicone rubber (SiR) insulators is crucial to ensure safe and stable operation. Several interface failures of 400 kV SiR insulators and insulators with many hot spots have recently been reported from the country's northeastern region. This study investigated the performance of fiber-reinforced plastic (FRP) rods of three 400 kV field-aged insulators, which were in service for about four years. The dye penetration and water diffusion tests are conducted to evaluate the FRP rod interface quality, porosity nature, and water resistance per the IEC 62217 standard. All the samples failed during the tests, indicating the presence of various defects, such as axial holes within the FRP rod and a bad-quality FRP-SiR interface. Further, numerical simulation was conducted using COMSOL Multiphysics to investigate the influence of air voids on the electric field distribution. Various scenarios were assumed, and interesting results about the failure mechanism obtained are presented.