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Lightning and High-Voltage Power Transmission Lines

Nature volume 134, pages 223224 (11 August 1934) | Download Citation



IN a paper read to the South African Institute of Electrical Engineers in November last by E. F. Rendell and H. D. Gaff, an analysis is given of the faults due to lightning on the overhead lines con necting two stationsthe Witbank and the Brakpan belonging to the Victoria Falls and Transvaal Power Co. of South Africa. There are two parallel three-phase circuits connecting the two stations and the maximum load is 350 kilowatts. The voltage between phases is the same as that of the British Grid, namely, 132 kv. The three lines forming each set are of steel-cored aluminium and are in a vertical plane, the distance between the two planes being 23 feet. There is no transposition of the conductors (sometimes done to avoid interference with neigh bouring telephones) and so they are parallel to one another. The distance between the top conductor of a set and the middle conductor is 12 ft., being the same as the distance between the middle and the lower conductor. An earthed guard wire was origin ally placed above the two sets at a distance of 18 ft. from the top wire of each set. The height of the lowest conductors from the earth averages 56 ft. The function of the guard wire is to ‘protect’ the circuits from lightning. There are 303 suspension towers for the circuits between the two stations.

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