Experience on partial discharge monitoring of power transformers

Partial discharge (PD) monitoring of high voltage and extra high voltage transformers is a tool that may provide timely and complementary information on transformer state with respect to other diagnostic techniques, such as dissolved gas analysis. Identification of source(s) generating PD and evaluation of the relevant time behaviour are, however, fundamental requisites in order to evaluate and plan maintenance actions. For this purpose, monitoring PD activity over a selected time span may be the appropriate procedure. In this paper, results obtained through partial discharge monitoring of a self-transformer are presented, showing the feasibility of PD identification and noise rejection.