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

Summary

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 corresponding to the power loss at each level of voltage & current which is the input to the electrical model. The electrical and thermal models run for numerous iterations until the arrester goes to thermal runaway or until it reaches a stable element operating temperature. The power input - heat loss curve is drawn for an arrester which will be used to find out the critical resistive leakage current at different ambient temperature. The critical resistive leakage current is computed for different ratings of the ZnO element for different Indian manufactures. This helps the Indian utilities to make use of the arrester to its maximum lifetime and also giving them enough time to remove the arrester safely from the system before it blasts. The prediction of the critical resistive leakage current is done by programming using MATLAB software.

Additional informations

Authors

CHARALAMPAKOS VASILIOS , PYRGIOTI ELEFTHERIA , POLYDOROPOULOU EFTYCHIA , Hering Maria, Speck Joachim, Backhaus Karsten