Line surge arrester selection to improve lightning performance of transmission lines

Line arresters are considered as an effective mean to improve the lightning performance of transmission lines, particularly in areas with high soil resistivity and lightning ground flash density. This work describes a case study concerning a 132 kV transmission line of EDEMSA (Empresa Distribuidora de Electricidad de Mendoza, Argentina), and investigates the most adequate solution concerning surge arrester location and type. The different variables, that have an influence on energy stress calculations, are evaluated to select the arrester characteristics. EMTP96 models are used to estimate the critical currents that exceeds arresters rated energy stress during direct lightning return-strokes for different tower footing resistance values. The analysis is carried out with reference to arresters of different classes in order to select the kind of protection to adopt along the line in order to minimising the arrester outage due to energy stress.