Coordinated Surge Protection System in a TT Wiring System: A Comprehensive Analysis of Performance

This paper delineates that the protection provided by a system of coordinated surge protection devices (SPDs) in a low voltage TT wiring network strongly depends on many selection and installation parameters. The outcomes provide a comprehensive guidance for both the designers of protection systems and the end user to understand the realistic scenarios of protection. Two connection configurations and four cases of lightning transient interception have been considered. The information inferred from the analysis clearly shows that the efficiency of the SPDs, even if they are connected under zonal concept, will depend on site-specific factors such as wire lengths between SPDs at different zones and the wire length from the final set of SPDs to the load, resistance values of the neutral earth at the substation and the consumers' earth. The three line to neutral and neutral to earth configuration is preferred over the three lines and neutral to earth configuration. SPDs may or may not operate in the ascending order of their voltage protection level. The substation earth could significantly affect the probability of equipment damage or reduction of the SPD life-time at a consumer facility.