In this paper, some results are presented from experiments concerning partial discharge (PD) behaviour of epoxy resin samples having 3 wt% nano- and 3 wt% micro-fillers, as well as epoxy samples having 3 wt%and1 wt% nanoparticles. The nano- and micro-fillers were TiO2 (titania). The main idea is to see whether a sample with PD at its inception voltage, still presents some tendency to charging effects below inception. An effort is being made to relate the present work with previous publications on the same main idea, as well as to previous research performed recently at Xian Jiaotong University, State Key Laboratory of Electrical Insulation and Power Equipment. It is indicated that with the samples investigated, although on some occasions random charging phenomena were observed below the inception voltage, it was not noted the same behaviour as with pure epoxy samples. Finally, a discussion ensues as to the definitions of the phenomena taking place below inception voltage.
