Developments on the Line Surge Arresters Application Guide prepared by the CIGRE WG C4 301
The CIGRE WG C4 301 is preparing a guide on line surge arresters (LSA). The goal of that document is to provide practical information on the use of line arresters in order to help electricity utilities to select appropriate solutions. This paper summarizes the major elements of the CIGRE WG document. It starts by listing the main reasons for LSA installation: lightning performance improvement, security of population, switching surge control, line upgrading and compaction, double circuit outage reduction, live line working, extended protection of substation. Then it discusses the respective advantages and disadvantages of line arresters with and without series air gap. Lightning flashover rate is a key aspect for evaluating the lightning performance of overhead lines. The next section summarizes the main steps of a procedure for lightning flashover rate calculation. The paper is completed with the study of the lightning performance of a 225 kV double- circuit. Double-circuit outages on double-circuit overhead lines often lead to critical power interruption problems. The case study presented in this paper compares a solution aimed at reducing the number of outages based on unbalanced insulation with a solution based on the installation of LSAs. Flashover rate calculations were carried out with a software tool based on the EMTP-RV and using a three-dimension electrogeometric model.