The Loss of Hydrophobicity of HTV Silicone Rubber in a Dynamic Drop Test

This paper presents the hydrophobicity performance of high temperature vulcanizing (HTV) silicone rubber (SIR) materials. Unfilled HTV and filled HTV with different concentrations of alumina trihydrate (ATH) and slica (SiO2) fillers are taken into considerations. Silica fillers with 3.6 mu m and 9 mu m mean particle size and ATH fillers with 4 mu m and 9 mu m mean particle sizes are investigated. The hydrophobicity performance of the HTV silicone rubbers are evaluated by using dynamic drop test (DDT) according to CIGRE TB 442 documentation. DDT were performed at constant test voltage of 5 kV at power frequency voltage of 50 Hz, at an ambient temperature of 23 +/- 2 degrees C for 1 ml/min contamination flow rate. Time-to-hydrophobicity loss for the HTV samples as well as the leakage current magnitudes were obtained for unfilled HTV and for different filler concentrations of ATH and silica incorporated with HTV.