The mechanism of water tree formation in insulating liquids

A new technique has been developed to study the growth of water trees. In this trees are grown around a high voltage conductor immersed in an insulating fluid and are observed using a video camera and time lapse recorder. It was found that the tree-like structures grow in a relatively short time if droplets of water or other liquid or solid particles are injected into the fluid. As in solid insulation tree growth depends on the presence of ions in the liquid, the frequency of the field applied to the conductor, the permittivity of the injected particles and the viscosity of the insulating fluid