Breakdown processes over large distances in insulating liquids of distinct chemical compositions

In this study we examine breakdown and prebreakdown phenomena in asymmetric geometry (point to plane) at large gap distances (up to 20 cm) under positive voltage steps (up to 500 kV) in liquids of distinct chemical families: saturated, aromatic and polyaromatic. Signal analysis shows that the currents are not continuous but are made up of bursts with different waiting times between them. The duration and number of these bursts vary according to the general chemical composition of the liquid. For example, there are numerous short bursts in mineral oil and a few long bursts in the aromatic liquids. The polyaromatic has a behaviour which retains features of both.<>