Computation of Effective Length of Enhancement for Vertical Electrode Under Lightning Transients

The performance of the grounding system is improved by adding enhancement conductors to the primary electrode as they result in low impulse impedance. This article proposes an optimized impulse impedance reduction approach to estimate the effective length of the enhancements of the primary electrode. The impedance of the enhanced primary electrode is computed by performing simulation experiments in a comprehensive dynamic circuit model. The enhancement's effective length is estimated from the correlation of the impedance with the enhancement length. From the relationship of the effective enhancement length with soil resistivity, impulse rise time, and current, an empirical expression to estimate the effective length of enhancement (ELEH) is obtained using numerical analysis. The obtained expression for ELEH is validated by field experiments.