Nonlinear dielectric behaviour of insulating oil under HVDC stress as a result of ion drift

The paper presents two nonlinear dielectric effects from literature in mineral insulating oil, when stressed with DC voltage. In the first part it is shown how current time measurements fit Kerr field strength measurements. In the second part, the nonlinear current time effect is noted for polarity reversal. Both effects are caused by oil intrinsic charge carriers and their special dielectric properties. The current-time-behaviour and the nonlinear field strength distribution are calculated solving the Poisson-Nernst-Planck-equation time dependently.