Economics of Single and Bundle Conductors for Extra-High-Voltage Transmission

1. A method has been developed whereby the optimum configuration and conductor area may be determined for a given EHV transmission line, taking into account all the parameters which have economic significance. 2. This method is general, and applicable to a wide range of system configurations, transmission distances, voltages, and loadings per circuit. Economic evalution factors may be varied to agree with available cost data, and the judgment and policies of the utility management. 3. This method is embodied into a digital computer program for the IBM705 computer, providing rapid computation of any case to be investigated. 4. Fifty-eight different cases were investigated in this study, to determine the effect of varying the system parameters and the economic evaluation factors over a wide range of values which are of practical interest for the United States and Canada. 5. Annual cost differentials between the minimum cost points for the various configurations are considerable and correspond to several per cent of the annual charges on the line investment. 6. The optimum configuration depends upon the particular values of the system parameters and economic evaluation factors. Therefore it is difficult to draw over-all conclusions, valid for all cases. Rather, each specific case will have to be investigated separately according to the method described in this paper. 7. In general, as the load per circuit increases, relative to surge impedance loading, the number of conductors per phase corresponding to the optimum configuration also increases. 8.