Experimental study of response of power distribution lines to direct lightning hits

In order to clarify the response of overhead distribution lines to direct lightning hits, experimental facilities were installed at the UHV Shiobara Testing Laboratory of CRIEPI. A lightning impulse current with a crest value of 18 kA and a waveform of (2/11) μs was generated through the impulse current generator with a high internal resistance of 400 Ω. This impulse current is not easily affected by the conditions of a distribution line side. Protective effects of surge arresters and an overhead ground wire against direct strokes to the pole of a distribution line were clarified experimentally. Experimental results showed a better protective effect than earlier calculated results. Overvoltages between a line conductor and the earth are inclined to have a short wavetail. The 50% flashover voltage of an insulator against overvoltages with a short wavetail is higher than that against overvoltages with a standard wavetail