Rethinking transmission line health indices under rising lightning activity

Health and condition indices (HI and CI), based primarily on physical inspections, are fundamental in asset management but show severe limitations in regions with high lightning activity. In a 230 kV transmission line (TL) in Colombia, failure rates vastly exceeded design Key Performance Indicators (KPIs) despite assets being classified in "good condition", evidencing the inadequacy of static evaluations. To bridge this gap, this study integrated the traditional HI with a multidimensional framework combining a ten-year spatiotemporal characterization of lightning strikes (2015–2024), physical insulation modeling, and induced overvoltage estimation. Results demonstrate that KPI deviations align with pronounced interannual increases in lightning activity strongly correlated with the positive phase of the El Niño-Southern Oscillation (ENSO), confirming the breakdown of climate stationarity and the emergence of localized exposure hot spots. Furthermore, induced overvoltages—amplified by high local grounding parameters—can exceed 50% of the Critical Flashover Voltage (CFO) even under moderate currents, explaining failures in assets lacking visible defects. Based on these empirical findings, a methodological roadmap is proposed to evolve toward a Dynamic Health Risk Index.