Electrical and mechanical properties of fly ash filled silicone rubber for high voltage insulator are investigated in
this paper. The fly ash studied is taken from subbituminous coal combustion which contains high amount of Silica (SiO2 )
and Alumina (Al 2 O3 ), majority in form of glass and quartz. In many literature, Silica and Alumina have been proven can
enhance electrical and mechanical performance of silicone rubber insulator. Measurements are conducted on various
amount of fly ash in RTV (Room Temperature Vulcanization) silicone rubber to find electrical and mechanical
characteristics of fly ash and RTV silicone rubber composite such as dielectric strength, volume resistivity, surface
resistivity, dielectric constant (relative permittivity), tensile strength, and hydrophobicity. Test performed according to
ASTM (American Society for Testing and Materials) standard. Test results showed that, on average, the dielectric strength
of materials are increase with increasing fly ash content. Maximum value of the dielectric strength achieved in 40% fly ash
content in silicone rubber. Volume resistivity of the materials are increase with addition of fly ash. The maximum volume
resistivity value is achieved in 30% fly ash content. Surface resistivity and dielectric constant also increase with increasing
content of fly ash up to 80% in the silicone rubber. Tensile strength of the materials, on average, are increase with addition
of fly ash content. The maximum increase in tensile strength, reached on the 30% fly ash content. Hydrophobicity test by
contact angle measurement of the materials are increase with addition of fly ash in the silicone rubber, with maximum
contact angle is reached in 30 % of fly ash content.