A new approach in the analysis of the water treeing phenomenon by using fluorescence microscopy and the thermostimulated creep

Electrical treeing and water treeing are both forms of electrical degradation. The authors have been devoted to a new approach to the phenomenon by using fluorescence and epifluorescence microscopies and thermostimulated creep. Most authors, using light microscopy or scanning electron microscopy, assume that water trees are made of a distribution of small non-connected cavities of variable sizes, ranging from 1 to several micrometers. In contrast to this model, others observed hollow microchannels or suggested from transmitted electron microscopy observations, that microchannels could result from the coalescence of cavities as small as 0.1 mu m. In order to understand the efficiency of the fluorescent dye in revealing the structure of water trees, some preliminary observations on a water tree, grown in a laboratory specimen, are carried out. Different sections from the same water tree which underwent three different treatments are collected.<>