Impact of ESDD-standardised pollution on partial discharge inception and AC breakdown voltage of 11 kV disc insulators

Outdoor porcelain insulators are significant in power distribution due to the fact that they offer insulation and mechanical support to overhead lines. Some of the environmental contaminants that may cause impairment of performance, especially under AC stress, are dust, salt, and moisture. The existence of moisture on the insulator surface can lead to the formation of soluble salts, creating a conductive layer that leads to increased leakage current, dry-band formation, and a reduction in flashover voltage. This experiment was designed to investigate the influence of the severity of pollution upon the AC breakdown voltage of 11 kV porcelain disc insulators based on the standard Equivalent Salt Deposition Density (ESDD). The conditions were controlled to simulate dry and wet states of clean, light, medium, and heavy pollution, as stipulated in IEC 60507. Besides, COMSOL Multiphysics, through the finite element simulation function, was used to imitate the electric field density and the leakage current for each level of pollution. The results showed that the breakdown voltage decreased with an increase in pollution, and the most meaningful outcome was that of wet conditions. It is also found through simulations that, in the case of heavy pollution, the strengthening of the electric field around the high-voltage electrodes becomes higher. The agreement between the experiment and simulation supports the modelling strategy and validates that the hybrid techniques are trustworthy in identifying the performance of the insulator in a polluted environment.