The impedance of ZnO varistor has dynamic characteristics when it is subjected to transient load
thus the dynamic characteristics should be considered in heat dissipating calculation. Based on the nonlinear electro-thermal characteristics of ZnO varistor
the heat dissipation model of the metallic oxide line arrester without gap(MOA) under transient time-varying load is established. Firstly
the change patterns of the ZnO varistor impedance under distinguished loads and temperatures are investigated so as to build a mathematical model of ZnO varistor impedance.Then
the model is substituted into the thermal dissipation calculation module. During the final time-dependent simulation progress
the real-time results are iterated back to the mathematical model
which means the material impedance parameters are adjusted in real time according to the temperature results. Experimental data verify that the calculation results of the heat dissipation model are in accordance with the actual situation. In the case of long heat dissipation time and heat dissipation under continuous operation voltage
the temperature curves of MOA are highly accurate after the dynamic characteristics of the ZnO resistor are taken into consideration.