Evaluation of the Impact of Underbuilt Wire on Back-Flashover Critical Current in Transmission Line

This paper aims to evaluate the improvement in protection against overvoltages, specifically the reduction in the back-flashover rate (BFR) resulting from direct lightning strikes, by employing the Underbuilt Wire protection technique on a transmission line installed over high-resistivity soils. For this analysis, real lightning current waveforms ranging from 10-100 kA were adopted, encompassing three scenarios: without the use of Underbuilt Wire, with Underbuilt Wire along the entire line section, and with Underbuilt Wire applied to a shorter line section. The research identifies the optimal installation approach that leads to increased critical current thresholds for back-flashover and provides additional technical insights that warrant consideration.