An analysis of partial diecharges that result from transformers is presented. The PSA-method (PulseSequence-Analysis) is applied to investigate the discharge behavior. It is shown that a PD data base, that comprises typical model defects, can be efficiently wed to identify the types of PD defects within high voltage (HV) equipment. When applying physically meaningful discharge parameters a reliable diagnostic decision can be obtained and the risk of misclassification can be reduced considerably.-* PSA -patterns of reference data --