Initiation and formation of partial discharges in mineral-based insulating oil

This paper reports the results of fundamental investigations concerning the behavior of partial discharges (PD) in mineral-based oil with the aim of characterizing the physical mechanisms that lead to the initiation and formation of PD pulses. First the influence of the parameters temperature, moisture, pressure and oil condition on the PD inception voltage, the apparent charge and the number of PD pulses are introduced. Furthermore some results achieved by investigating the shape of PD pulses and the behavior of visible PD channels using the Schlieren technique are explained. The paper ends with a discussion of the obtained results