Differences in the response of transmission lines subjected to the currents of negative and positive lightning flashes: Influence of ground terminations

The differences on the lightning response of transmission lines, whose towers are subjected to the impression of pulses of current of first negative return strokes and of positive flashes, are determined by computational simulation. It is shown that the amplitude of the resulting transient overvoltages across insulators per unit of impressed current is much larger for negative return strokes. As most of the traditional procedures for assessing lightning performance of transmission lines ignore these differences, their results can exhibit significant errors.