Dependence of Breakdown Voltage of Silicone Liquid on Temperature

Breakdown voltages of silicone oil in a sealed off container with gas were measured. It was found that the ac breakdown voltage increases with temperature when nitrogen or air are used as gas. On the other hand, in vacuum the ac breakdown voltage does not depend on temperature, except at -20°C. The impulse breakdown voltage was found to be temperature independent. These results can be explained on the basis of breakdown initiation due to evolution of gas from the sample oil.