Study of the generation by acute electrodes of a gaseous phase in dielectric liquids subjected to high A.C. or step voltages

The gas generation in a liquid is studied with a test arrangement simulating an all-film capacitor, a model previously developed. In the case of step voltages, the generation threshold voltage is obtained with good accuracy and low spread by recording bursts on the transient currents. These bursts are associated with the presence of streamers from which result gas generation. The presence of space charge, which reduces the field at the acute electrode and produces an increase in the measured generation voltage, is evidenced in various experimental conditions. Another main result is that the gas generation voltage depends strongly on the nature of the solid material adjacent to the foil edge. It is hypothetised that the double layer at the insulator/liquid interface plays a role in the streamer propagation.