Induced Overvoltage at the Terminations of a $10 \text{kV} / 220 ~\mathrm{V}$ Co-Pole Overhead Distribution Lines Caused by Rocket-Triggered Lightning Strikes 10 Metres Away

An indirect triggered lightning event 10 meters away from the L-shaped 200-meter-long low-voltage (LV) overhead distribution lines, which were laid on the same pole as the upper 10 kV lines was reported. At the line terminal 20 meters away from the stroke location, despite the protection action of SPDs located 10 meters away, the amplitude of the lightning-induced overvoltage (LIV) from 8 return-stroke pulses can reach up to 7000 V. Under the neardistance lightning electromagnetic pulse (LEMP) environment, the SPDs on the lines may not act stably in each discharge pulse process, even if it is not damaged. Due to the additional <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{1 0}$</tex>-meter distance from the SPD and the LEMP coupling, there are large fluctuations in the residual voltage stage, ranging from 0.5 kV to 2.5 kV, and highfrequency spikes can reach 4 kV, i.e., far above the rated value. These two issues could result in the failure of the SPD to protect the LV distribution line from close lightning strikes, allowing surges to penetrate into the room and threaten the electricity safety. At the other line terminal 100 meters from the strike point, the SPD protection keeps both high-frequency spikes and the amplitude of the low-frequency limit voltage within 1.5 kV. This finding highlights the significance of the installation position and lead-wire length of the SPD to minimize additional risks from LEMP. Test standards should consider including multi-pulse lightning surge simulation to ensure the reliability of SPDs in strong lightning environments.