Development of a high performance high voltage insulator for power transmission lines from blends of polydimethylsiloxane/ethylene vinyl acetate containing nanosilica

Abstract

Ceramic materials are commonly used as outdoor insulators for high voltage power transmission lines. Presently these ceramic insulators are replaced by composite polymeric insulators with silicone rubber (PDMS) housing, especially in industrial areas with pollution. Silicone rubber is chosen for housing material because of its excellent aging resistance, electrical properties, tracking resistance, and stable hydrophobicity which in turn control the tracking resistance. However, the material has deficiencies like poor mechanical strength and high cost. To improve the mechanical properties and reduce the cost, silicone rubber is blended with ethylene vinyl acetate copolymer (EVA). The optimum blend composition is found to be PDMS/EVA 60/40 w/w. But in doing so some reduction in hydrophobicity is observed, thus adversely affecting the tracking resistance. To improve hydrophobicity, the addition of nanosilica at the level of 6 phr is found to be the optimum. Thus high performance outdoor insulators can be produced from a PDMS–EVA blend containing 6 phr nanosilica. Different types of accelerated aging tests were performed on the insulator samples to simulate their aging behavior under different real life aging processes.