METAL OXIDE SURGE ARRESTER (MOSA) IS WIDELY USED FOR LIMITING OF TRANSIENT OVER VOLTAGES WITH ABSORBING THEIR ENERGY. TEMPERATURE AND HEAT LOSS OF ZNO VARISTORS HAVE GREAT ROLE IN PERFORMANCE OF ARRESTER AND MAY CAUSE ELECTRO-THERMAL STRESS, INCREASE OF LEAKAGE CURRENT AND RUN HEATING PHENOMENON.
ELECTRO-THERMAL MODEL IN A UNIFORM INCLUDE PERFECT ELECTRICAL MODEL AGAINST TRANSIENT OVER VOLTAGES, BEHAVIOR OF VARISTOR WITH TEMPERATURE AND HEAT TRANSFER MODELING OF ARRESTER. THIS PAPER CONSIDER ABOVE MATTERS AND DRAFT A ELECTRO THERMAL MODEL AND APPLIES IT FOR A STATION CLASS SURGE ARRESTER FOR SIMULATION OF THERMAL STABILITY TEST ACCORDING STANDARD TEST.