Analyzing the Root Cause for Insulator Failure through Investigating the Insulator Performance under Environmental Stresses

Previous investigations result with issues regarding insulators premature aging and degradation process. Recent case of an outage in power plant showed unusual pattern of insulator failure. Insulators operating under various adverse conditions including presence of water, fog, dew and other contaminants are affected by these factors in a way that field enhancement that leads to flashover activity is generated. To identify the root cause of the insulator failure, the service conditions of a polymer rod type 110 kV insulator were simulated using COMSOL Multiphysics (Mph). Simulations relate to presence of water droplets, uniform and non-uniform pollution layer on the insulator surface, and formation of dry band areas. In order to simulate various types of pollutants present on the insulator surface, the pollution layer is modeled as a conductive layer for different values of conductivity. The provided results in the paper, pointing out critical weakened spots due to presence of various contaminants, should be used as a detection tool to determine whether this type of stresses could have contributed to the unusual mechanism of insulator failure. Deeper understanding and knowledge of the failure mechanism may be useful in order to prevent early failures of insulating systems in general.