Abstract
Measurement of lightning surges originating from natural and rocket-triggered lightning strokes in winter has been carried out on a real-size test transmission line since 1987. During November 1993 to December 1995, fifteen flashes which struck the test transmission line were observed. In one of the fifteen cases, the arresters equipped on the test transmission tower operated and well controlled the voltages across the insulators. In another case, a four-phase backflashover was observed on the upper and middle phases. The calculated results of the multi-phase analysis by EMTP agreed with the measured waveforms when the timing of the flashovers was given. But the four-phase flashover phenomenon was explained neither by the integration method nor by the leader development model.
