Influence of charging voltage magnitude on time domain dielectric response of oil-paper insulation

Polarisation current profile varies non-linearly with a magnitude of charging voltage. This implies performance parameters obtained from polarisation-depolarisation current and those measured using specialised equipment cannot always be compared. Results reported in this study suggested that the non-linearity in insulation response can be explained in terms of the interaction between space charge and insulation conductivity. The influence of using different charging voltages and its effect on performance parameter calculation is investigated in this study with the help of laboratory samples. It is shown in this study that with the help of a trained artificial neural network, it is possible to identify the charging voltage at which insulation response exhibits minimum non-linearity. To test the accuracy of the proposed method performance parameters measured using commercial equipment are compared with those calculated from the polarisation current profile.