Experience on measuring partial discharges in paper/oil medium-voltage distribution transformers

This paper deals with partial discharge measurements in oil-filled distribution transformers. Measurements are performed using antenna sensors, bearing in mind that these transformers are almost never equipped with bushing taps, so that alternative means for partial detection need to be devised. A simplified model is presented to investigate the emission pattern associated with partial discharge phenomena inside the transformer. The model is validated through measurements and computer simulations, and serves the purpose of designing an optimum sensor. Eventually, PD measurements on field on distribution transformers are discussed.