Effect of Tower Footing Resistance on Back Flash over across Insulator in a 132 Kv Transmission Line

This study conducts a thorough evaluation of the influence of tower footing resistance on the estimation of over voltages across the insulator caused by lightning strikes. The paper employed the Electric circuit simulator programme (ECSP) to examine the effect of footing resistance and lightning stroke on back flashover on the insulation of a 132 kV transmission line. The study assumes an insulator withstand voltage of 750 kV, lightning strikes of 10 kA, 20 kA, 30 kA, 40 kA, 50 kA, and 100 kA, and a footing resistance range of 5 Ω to 90 Ω. The findings reveal that as the amplitude of the lightning stroke grows, so does the voltage across the insulator, while the tower footing resistance decreases. A good tower footing resistance only helps grounding at 50 Hz, and it is also critical to keep the tower footing resistance and inductance low to ground high frequency lightning surges. This highlights the importance of considering both lightning stroke characteristics and tower grounding conditions in the design and analysis of transmission line systems.