A review of definitions, algorithms and validation procedures relevant to the identification of defects supporting Partial Discharges (PD) and separation of mixed pulse-signals which are the main steps of diagnostic of insulation systems based on PD measurements, are presented in this paper. The fundamental requirements to obtain valid insulation diagnosis and avoid misleading evaluations of the defects generating PD, are discussed considering also a possible future development of fully automated diagnostics and smart instruments. This presentation summarize the current investigations conducted by the Research Unit of the Dielectric Materials Lab. of the University of Trieste (Italy)
