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Partial discharge (PD) detection can give useful information for the diagnosis of electrical apparatus, but data interpretation can be impossible if several sources are simultaneously active. Pulse characterization can be used to identify the source origin in PD measurements. The distribution of energy at different frequencies helps in distinguishing several types of discharges. The parameterization of pulses by means of spectral power ratios (PR) has been studied as a reliable technique to represent different characteristics in high-frequency current pulses in high-voltage tests. In this study, the separation of PD sources by means of PR maps is proposed. This approach has proven to be effective in the identification of PD sources when two electrical insulation systems are simultaneously subjected to discharge activity in controlled experiments where internal, surface and corona discharges were occurring. The flexibility of the system to improve cluster separation is shown, and measurements are also made on a real insulated power cable, where two simultaneous PD sources were successfully identified.
partial discharges; electrical insulation; power ratio maps; clustering techniques; spectral power