Copper Conductors for Overhead Lines

Abstract

IN a paper read by Messrs. G. W. Preston and H. G. Taylor in London on April 12 before the Institution of Electrical Engineers, the creep of copper conductors and their initial non-elastic extension are considered in relation to their effect on sags and their compensation by an increase in erection tension as an alternative to pre-stressing. Information is given on the annealing characteristics of hard-drawn copper and copper-alloy conductors, with special reference to the effect of impurities in the metal, and maximum safe operating temperatures for such conductors are discussed, together with maximum permissible current loadings. Hollow copper conductors of various types for super-voltage lines are described, and the features of cadmium-copper conductors are dealt with in comparison with other types of high-tensile overhead conductor. Steel-reinforced copper conductors receive special attention, particularly in regard to the protection from corrosion of the steel wires, and results of a long-time investigation are given in full, with conclusions and recommendations. Copper-clad steel wires, their characteristics and use as reinforcement in copper conductors are discussed. Details are given of developments in the application of compressed sleeve joints to copper and copper-alloy conductors, suitable joints for cadmium-copper and steel-cored copper conductors are described and test results given.