Characteristics of induced voltage on overhead transmission line produced by lightning

Observations of voltages on transmission lines induced by natural lightning and artificially triggered lightning are investigated. The result shows that the initial continuous current (ICC) of one artificially triggered lightning produced a significant induced voltage with a maximum value of -2.2kV and lasting time of 75.6ms on the transmission line. Waveform of the induced voltage and ICC has a same variation tendency. Induced voltages produced by return strokes of artificially triggered lightning on transmission line exhibit bipolar pulses, with positive-polarity dominating. The positive and negative peak voltages produced by return strokes are 4.6kV and 10.3kV respectively. Induced voltages on the transmission lines produced by negative natural return strokes at near distances are also bipolar pulses, but when the lightning struck at a far distance, the induced voltages are mainly unipolar. More than 90% first return strokes produce larger induced voltages than subsequent return strokes of natural cloud-to-ground(CG) lightning. The amplitudes of induced voltages produced by first return strokes are typically 2-3kV, with durations of about 200us, which are longer than those produced by subsequent return strokes (about 100us). The wavefront time is about 18us, which is about 1/3-1/2 of the wavetail time. The induced voltage on the transmission lines produced by lightning is linearly correlated with the ratio of lightning current to the distance between lightning and the transmission line.