Development of an Electro-Thermal Model for ZnO Surge Arrester Under Contamination

Abstract

AN ELECTRO-THERMAL MODEL FOR A ZINC OXIDE (ZNO) SURGE ARRESTER UNDER CONTAMINATION TESTS IS PRESENTED. THE MODEL IS BASED IN THREE SUB-MODELS: ELECTRICAL, THERMAL AND CONTAMINATION, WHICH INTERACT IN ORDER TO OBTAIN THE SURGE ARRESTER PERFORMANCE UNDER CONTAMINATION TESTS. THE ELECTRICAL MODEL IS OBTAINED FROM MEASUREMENTS AND IS BASED ON A CAPACITANCE AND A NON-LINEAR RESISTOR. THE THERMAL MODEL TAKES INTO ACCOUNT THE HEAT GENERATED AND DISSIPATED BY THE COLUMN OF VARISTORS AND ITS SURROUNDINGS. THE CONTAMINATION IS REPRESENTED BY A DYNAMIC IMPEDANCE OBTAINED FROM MEASUREMENTS IN THE ARRESTER COLUMN DURING CONTAMINATION TESTS. THE FULL MODEL IS VALIDATED BY CALCULATING THE TEMPERATURE INCREASE DURING CONTAMINATION TESTS CARRIED OUT IN A TWO UNITS ZNO SURGE ARRESTER, CLASS 190 KV. FINALLY, THE RESULTS OF THE EFFECT OF SEVERAL DESIGN AND CONSTRUCTION PARAMETERS IN THE VOLTAGE AND TEMPERATURE DISTRIBUTION IN THE ARRESTER COLUMNS DURING CONTAMINATION TESTS ARE PRESENTED.