Creeping discharge on solid/liquid insulating interface under AC and DC voltages

This paper deals with the propagation of discharges on liquid/solid interface under ac and dc voltages using a point-plane electrode arrangement. The tests are carried out on different samples of Bakelite immersed in mineral oil. The final length of surface discharges and the associated currents are analysed as a function of the shape and the polarity of the voltage. It is shown that the final discharge length increases with the voltage and decreases when a hydrostatic pressure is applied. The number of creepage discharge branches, the associated current pulses and emitted light are also reduced when the pressure is increased.