On PD mechanisms at high temperature in voids included in an epoxy resin

In this paper the effects of temperature on partial discharge (PD) activity taking place inside a spherical void in epoxy resin system are studied, In deed, some experimental tests previously performed on specimens, having dif ferent void shapes, under multi-stress condition of temperature and voltage , have shown very different PD amplitude distributions at temperatures high er than ambient. However, this phenomenon cannot be explained only by takin g into account the different thermobaric conditions of the enclosed gas. In consequence of the general physical inaccessibility of such voids, a study is here performed using a numerical model based on an evolutionary optimiz ation algorithm. This is used to evaluate the range values for the physical parameters of the insulating system influencing the observed changes in PD activity. Finally, comments are presented about the adopted criteria by wh ich the comparison between the experimental data and the simulated ones is performed, and about the interpretation of the dependence on temperature of the experimental PD.