Influence on Low-Voltage Surge Protective Devices of Overhead Distribution Lines Due to Nearby Return Strokes

We present our measured residual voltages and current flow of zinc-oxide surge protective devices (SPDs) connected to an overhead distribution line from a nearby rocket-triggered lightning flash that involved 11 return strokes. The obtained results show that, owing to the preceding leaders, the residual voltage during the leader-return stroke stage exhibited initially a positive impulse, after which, the residual voltage changed polarity due to induced coupling to the power lines by return strokes. The durations of SPD residual voltages caused by the 11 return strokes range from 95.2 to 269.0 μs with mean 157.3 μs. The currents flowing through SPDs span an amplitude range from 198.3 to 961.0 A with mean 506.0 A. The average 10-90% risetime is 16.8 μs, and the average half-peak width is 67.1 μs. The energy absorbed by SPD ranges from 7.6 to 77.8 J with mean 34.6 J. It is shown that the lightning flash with 11 return strokes did not damage the SPD with a nominal discharge current of 20 kA. Moreover, the average 10-90% gradient of return stroke current is found to be a key factor that determines the peak current flowing through SPD and the energy consumed by SPD.