Electro-Thermal Modelling to Determine the Critical Resistive Leakage Current for ZnO Polymer Surge Arrester

In this paper Electro-Thermal modelling of the Polymer Zinc Oxide (ZnO) surge arrester is used to predict the critical resistive leakage current magnitude at which the arrester has to be safely removed from service before it fails. The electrical model is created using the Voltage-Current-Temperature (VIT) characteristics obtained on typical ZnO element experimentally. The power loss is computed from the V-I-T characteristics of the ZnO element for different values of operating temperature & voltage. The thermal model represents the thermal properties of the arrester components as an electrical analogous circuit represented by resistance & capacitance. The power loss calculated by the electrical model is the input to the thermal model. The thermal model computes the new temperature…