The effects of salt contamination deposition on HV insulators under environmental stresses

This paper examines the issue of salt contamination accumulation, flow of leakage current and surface flashover on high voltage insulators. Artificial contaminants were prepared using NaCl and distilled water. With long-term accumulation of salt particles on high voltage insulators in the presence of wind, ambient temperature, humidity, fog and moisture, conducting layers is formed on insulators´ surface. This conductive layer provides an ideal path for leakage current to flow from the high voltage conductor to the grounded side of the insulators. Insulators´ layer moistened and heated due to environmental stresses which cause an increase in leakage current and dry bands formation. Partial arcs can occur across the dry bands. Under favourable conditions a complete flashover might occur. The performance of the polluted insulators mainly depends on the conductivity of the polluted surface layer or on the equivalent salt deposited density of the polluted surface layer, which are affected by environmental conditions. Insulator is tested with different conductivities in a series of experiments including ESDD and NSDD measurement. COMSOL Multiphysics software is used to simulate and determine the electric field and potential distribution as well as the resulting leakage current flow on its polluted surface. The measurement results have been compared with the COMSOL results and found to be in good agreement. Outcomes will lead to the modelling of insulators and electric field response of insulators under different conductivities and environmental stresses.