The effect of external pressure on partial discharges and post-breakdown stages in LUKOSIOL

The characteristics of internal partial discharges in LUKOSIOL as a function of the applied voltage and the external pressure have been measured. The partial discharge measurements were performed with the help of Phase Resolved Partial Discharge Analyzer. The negative charge of partial discharge increased with the voltage and radically decreases at higher pressures. The pressure also caused an increase of the breakdown voltage and had influence on the development of post-breakdown stages — a vapor channel. From this strong dependence on the external pressure of the discharge characteristic results that pre-breakdown stage are connected with the gas phase. The time development of vapor channel was recorded by a high-speed camera.