Observation on induced voltages on overhead distribution lines caused by natural lightning

This paper carries out a summary and analysis on the observation result of induced voltage waveforms caused by nearby natural lightning on 220-V rated low-voltage overhead distribution lines in Guangzhou Field Experiment Site for Lightning Research and Testing (GFESLRT) during Summer 2008. It can be observed that when surge protective device (SPD) is not connected, the maximum peak value of induced voltages caused by seven lightning return strokes reaches 6.12 kV. When SPD is connected to the test line, the positive and negative peak values of lightning induced voltages on the live conductor and neutral conductor are less than 1.3 kV. Despite that induced voltages on two wires erected at the same height of an overhead line are almost the same, although some peak values of the induced voltages are not exactly the same. Lines with SPD connected can be protected effectively, while the waveforms are greatly different from the residual voltage waveforms of the SPD under impulse current obtained in laboratory. Measured peak values of induced voltages in this paper are much smaller than estimated values by the Rusck theory.