A Practical Evaluation of Surge Arrester Placement for Transmission Line Lightning Protection

The use of metal-oxide varistor surge arresters (MOVs) in lightning protection of overhead transmission lines to improve reliability is of great interest to electric utilities. However due to economic reasons, it is not possible to completely equip an overhead transmission line with surge arresters at each transmission structure. In this paper, an evaluation of lightning protection design on a 115 kV transmission line using surge arresters, utilizing a model based on field data, is presented. The model developed is used for computer simulation using the Alternative Transients Program. Various design procedures aimed at maximizing the reliability of service on the transmission line using a minimal number of surge arresters are analyzed. Different designs considered for transmission line lightning protection using MOV arresters include: the use of a different number of surge arresters per tower, distance between towers with surge arresters and the dependence of these configurations on tower footing resistance. The lightning protection designs are analyzed using `lightning flashover charts,' proposed in this paper. Also, an analytical model of two 115 kV transmission lines in Southwest U.S. has been developed and different surge arrester location strategies used on these transmission lines have been analyzed. Practical experiences and effectiveness of various lightning protection designs used on these transmission lines are discussed.