With four case studies (dry-type transformer, power transformer, GIS, generator) this paper describes the principle of synchronous multi-channel PD measurements and its benefits for PD data evaluation. With respect to monitoring the tracing of a charge value as QIEC over the measuring time is not sufficient to assess the PD activity of an HV apparatus. With state-of-the-art PD evaluation techniques as 3PARD and 3CFRD a simple and fast (all calculations during the PD measurements are carried out in real-time) tool is available to separate PD from noise. Separated PD sources can easily be back-transformed to phase-resolved patterns or pulse sequence patterns, for instance, to be evaluated automatically by computerized PD expert systems or by experienced human experts.