Superhydrophobic Coating for Performance Enhancement of Polymeric Outdoor Insulators Used in HVDC Systems

Polymeric outdoor insulators in HVdc systems encounter additional challenges beyond the typical environmental and electrical stresses seen in HVac systems, such as increased pollution accumulation, surface charge accumulation, more severe discharges, and a higher failure rate. This study presents the development of a superhydrophobic coating made from polydimethylsiloxane (PDMS) and hydrophobic nano silica (SiO2) for polymeric outdoor insulators, achieving excellent water-repellency and self-cleaning properties. Experimental evaluations under various conditions—dry, clean fog, clean rain, salt fog, and salt rain—demonstrated significant performance improvements: for example, under salt rain conditions, the flashover voltage increased by 97.3% (from 22.16 to 43.72 kV), while the leakage current (LC) reduced from 32.2 mA to 193 $\mu $ A. Simulation and experimental results demonstrate the superior performance of the superhydrophobic insulators, ensuring more stable and reliable operation of composite insulators in HVdc systems.