Insulators Used in Outdoor Power Applications: Materials and Coatings

The optimum design of the electrical insulation system is essential for robust operation of the power grid and its equipment/devices. Accordingly, choosing the insulating material is crucial, so the insulation can withstand suffering the high stresses caused by abnormal operating conditions and external effects. The solid insulating materials, like ceramics and plastics, have been used vastly in the power applications since they can satisfy the required electrical and mechanical aspects. In this work, the outdoor insulators are demonstrated and classified into single and composite materials. Although they have been operating effectively, the faults still occur causing failure of the device or the whole system. Consequently, the failure causes are illustrated. Coating the insulator surface is discussed elaborately since it aims at enhancing the insulator performance to cope with the adverse effects causing the failure. Either hydrophobic (HP) or field graded material (FGM) coating is used depending on the failure cause. The research works that investigated coating same material insulators are compared together. The comparisons serve as a useful guide for choosing the proper coating and might be helpful for future work prospective developments.