Mechanical properties of HTV materials used in composite insulators in strong wind area

Composite insulators were extensively applied in outdoor insulation for the extraordinary performance of hydrophobicity and anti-aging property. Whereas HTV silicone rubber had low elastic modulus and the stiffness was not high enough to resist high speed wind. In northwest China there are many storm-wind areas where the designed wind velocity of transmission lines could reach to 42 m/s. The high speed wind induced sustained and intensive oscillation of insulator sheds and finally leaded to fracture failure at root of it. The oscillation problem of sheds and fatigue and fracture properties of HTV materials haven´t been paid enough attention before, for the composite insulators utilized in strong wind area. This paper researched on oscillation performance of one type of composite insulator in wind tunnel with applied wind speed from 0 m/s to 60 m/s. The oscillation phenomenon was recorded with high speed camera to measure the oscillation magnitude and frequency. Four HTV silicone rubber samples were tested for its fatigue resistance performance. The developing process of crack along the groove of silicone rubber samples was observed and the flexing cycles and the cycles that the micro-crack developed into fracture were measured.