The Use of the Pulse Sequence Analysis to Monitor the Condition of Oil

Partial discharges in oil are influenced by the actual dielectric properties of the liquid. Especially degradation products or water may influence the electric strength, the local field distribution in the surrounding of defects and hence the ignition and the sequence of partial discharges. As a consequence of dielectric forces the local concentration of polar molecules in non homogeneous electric fields is influenced and especially at spots of extreme high electric fields (at which usually partial discharges start) a local accumulation may occur and influence the partial discharge phenomena. The analysis of the sequences of partial discharges (Patsch and Berton, 2002) as well as the pulse shapes of the signals (Patsch et al., 2002) from the coupling device in differently aged and/or polluted oil shows characteristic differences. Possibilities to use characteristic parameters for diagnostic purposes and especially their correlation to other dielectric properties will be discussed in detail.