Progress in the Determination of AC/DC Resistance Ratios of Pipe-Type Cable Systems

This paper presents a summary of measurements made to determine ac/dc resistance ratios of large conductor, high voltage pipe-type cables of modern design. The method and circuit used are described. The measured ac/dc resistance ratios of similar size compact segmental copper conductor aluminum conductor cables are presented. The effect of temperature on the ac/dc resistance ratios is reported. Test results are compared with ac/dc resistance ratio calculations made using the Neher-McGrath method. The accuracy of ac/dc resistance ratios which can be anticipated by the use of the Neher-McGrath method is improved by the use of a transverse conductance factor kpc for cables in cradle configuration and a new factor for calculating in-pipe resistance ratios. The measurements have resulted in the development of cables with lower ac resistance.