Sammendrag
An automated setup for testing dielectric performance of liquids in a small point-to-plane gap is presented. It provides step voltages with rise times around 30 ns, with amplitudes up to 90 kV. Breakdown studies of thirteen different liquids were conducted with a gap distance of 4 mm in a test cell containing 20 ml liquid. The liquids were circulated and filtered after each breakdown to remove carbonized particles and relax space charges. Time to breakdown versus applied voltage was recorded, and for streamers that stopped mid gap, shadow graphic images of streamer structures were taken. Multivariate correlation studies between streamer properties and physio-chemical parameters of liquids were made, indicating relevance of liquid evaporation and electronic states of molecules.