Analysis of an alternative filler for RTV silicone rubber coatings applied in outdoor insulation

Summary

The performance of electrical insulation is one of the main factors associated with good functioning of the electric power system. The transmission of electricity between generator and consumer centers must have good levels of continuity, reliability and low cost. Ceramic and polymeric materials are commonly used in the composition of insulation. The use of polymeric insulators has shown a growing tendency in the phases of project development and maintenance of distribution and transmission networks. The reduced weight, resistance to vandalism and good performance in regions with high levels of pollution represent some advantages of polymeric insulators compared to traditional ceramic insulators. The hydrophobic properties of polymeric material prevent the formation of a conductive film on the insulator surface due to low surface energy. Consequently, the development of leakage current and occurrence of flashover are reduced. The application of hydrophobic coatings on the surface of ceramic insulators allows to improve the performance of the outdoor insulation and prolong the operational life, even in areas under severe weathering conditions. The introduction of fillers into the coating formulation affects the physico-chemical properties and allows for improved performance and reduced costs associated with fabrication and maintenance. This work will investigate the performance of polymeric coatings with added organic fillers. Three types of room temperature vulcanized silicone rubber will be produced employing different concentrations of carnauba wax powder. The coatings will be applied to the surface of glass insulators and subjected to a cyclic salt fog test. The filler dispersion in coating was evaluated by Scanning Electron Microscopy. The hydrophobicity was analyzed periodically using static contact angle method. From the results, it was verified that coating added 10% of carnauba wax presented values of leakage current near to unfilled coating. In addition, less loss and faster recovery of hydrophobicity was verified for coating with 10% carnauba wax.

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Keywords

RTV silicone rubber, carnauba wax, morphology, leakage current, hydrophobicity.