Decomposition Products of Silicone Liquid Due to Electric Discharge

Silicone liquid can be used at relatively high temperatures, for instance as an impregnant in transformers for use in trains, because it has high thermal stability and low flammability. This paper describes decompositions of silicone liquid due to electrical discharges, such as arc discharge and partial discharge. It was found that hydrogen, carbon monoxide and cyclic dimethyl siloxane (D4) are produced due to electrical discharge as in the case of thermaln degradation. However, only one kind of dimethyl siloxane (D4) was found, whereas D3, D4, D5, and D6 were found in thermal degradation [2]. Moreover, the ratio of the gaseous products to cyclic dimethyl siloxane compounds for partial discharge is much smaller than the same ratio for arc discharge. In both cases the ratio is much larger than the ratio found for thermal degradation [2].