Thermal analysis of a ZnO surge arrester using the finite element approach

In the design stage of a metal oxide surge arrester the heating and cooling simulation is particularly important since the temperature-rise in the ZnO elements, caused by absorbing surge energy, can produce the phenomena of thermal runaway. In the present paper the heating and cooling analysis of a ZnO surge arrester under different operating conditions is performed using CAD/CAE techniques. This analysis was performed taking into account the steady-state and the transient heat transfer phenomena. The results were obtained using CADdyTERM, a finite element software package developed by the authors. These computer programs allow to handle the complex geometry of the device as well as the highly non-linear resistance of the metal oxide elements. Finally the results are discussed and some important and practical conclusions concerned with the heating and cooling of the surge arrester are pointed out.