Influence of conductor designs and operating temperature on the economics of overhead lines

Line designs have been prepared covering temperate and tropical conditions for an alternating voltage of 132¿1500kV and a direct voltage of ±125 to ±1000kV. The conductors and bundle arrangements were selected taking into consideration corona, radio interference and the factors which influence the current-carrying capacity of a conductor. Evaluation of capital costs of lines and specific transmission costs have been carried out for the above designs. The interrelationship between the conductor size, the load transmitted, the conductor temperature and the specific transmission cost is shown for selected loads. For the typical parameters assumed in the study, it is concluded that, for a given load, the optimum economic transmission cost occurs with a relatively large area of conductor cross-section and at relatively low conductor temperature.