Reduced performance of overhead power line insulators can be related to the presence of contaminants deposited on their surfaces. Contaminant deposition can form, in the presence of moisture, condensation or rain, a conductive or partially conductive surface layer that can be the cause of electrical discharge phenomena (flashover).This research aims to develop coatings that reduce the accumulation of surface contaminants, thus minimizing the probability of discharges on insulators.

The use of hydrophobic coatings results in reduced adhesion and easier leaching of soluble and insoluble contaminants due to the lower surface energy. The total length of the insulation chain is reduced compared to glass or ceramic insulators under the same contamination conditions.

Based on this, silicone-based hydrophobic coatings (PDMS) have been developed and characterized, and the hydrophobic properties have been improved with the use of appropriate chemical modifiers or fillers (stearyl methacrylate and PVDF). In the case of stearyl methacrylate, surfaces with static contact angles of about 110° and low hysteresis of the dynamic contact angle were obtained.

Laboratory washout tests against soluble and insoluble contaminants gave evidence of the anti-contamination capabilities of these surfaces, which were 2 to 4 times higher than those of uncoated glass. Hydrophobic surfaces were also obtained by deposition on glass of zinc oxides with special micro- and nano-crystalline structures: SEM images of these oxides show different geometries according to the synthesis conditions, and contact angles greater than 150° and low hysteresis were obtained by depositing prismatic microcrystalline oxides.

A field study of the anti-contamination performance of an RSE-developed hydrophobic coating applied to a chain of hood and pin insulators exposed in the ContIsola test field was performed. Preliminary results do not show a significant reduction in the amount of deposited contaminants, but the study is still in progress.

Two analytical methods (ion chromatography and ICP-OES) were developed and validated in the RSE laboratories to determine the composition of the soluble contaminants present on the surface of the isolators during the ContIsola experimental campaign. A potentiometric method was also used for the analysis of metals, anions, and cations in water samples obtained during the washing of the isolators.