Circuit modelling of aged-polluted polymer insulators based on measured leakage current characteristics

A new equivalent circuit model for aged-polluted polymer outdoor insulators is proposed here. The structure of the model is constructed as such that it can be applied in investigating the effect of insulator aging and dry band discharge intensity on leakage current (LC) characteristics. To implement the capability of modelling aged insulators, the measured leakage currents from laboratory tests on field aged MV insulators with different level of aging and hydrophobicity were examined. Furthermore, the samples were artificially polluted and the corresponding measured leakage currents from laboratory tests were employed as references. The proposed circuit model can consider the effect of pollution by its topology and represents the aging phenomenon of insulator by the changes in the values of its elements. High similarity between test results and model outputs has confirmed model ability to represent aging effect on LC characteristics. Finally, mathematical equations for model parameters in terms of aging level are extracted using curve fitting, in order to predict the age and life-time of polymer insulator.