Properties of Acoustic Emission Signals Coming from Partial Discharges Caused by Modeled Sources Immersed in Transformer Oil

Investigation results concerning acoustic emission signals coming from partial discharges generated by modeled sources are presented in the paper. These sources have been made using different bushing ends (without any extra elements and with a thread or a pike) situated directly in the oil, but without screens typical for partial discharge investigations in a bushing. Measurements have been carried out using own measuring acoustic emission system DEMA-COMP and - in a parallel way - computer-aided partial discharges measuring system TE 571 (produced by the firm Haefely Trench). Fundamental and advanced analysis of acoustic emission signals has been made. These signals were recorded in 20 measuring situations which need to multiple installation of acoustic emission sensors. Conclusions resultant from own originate advanced analysis of signals content description of properties revealed by defined acoustic emission descriptors.