Electrical and Thermal Analyses of Parallel Single-Conductor Cable Installations

The unequal current distribution in parallel single-conductor cable installations can lead to an excessive temperature rise. This paper presents a cable model and a procedure of coupled electrical and thermal analyses for the evaluation of the current, loss, and temperature in the cables of concern. The cable model and analytical method were tested experimentally on a cable system in the laboratory. The procedure was applied to evaluate the current rating and the temperature rise in a particular single-conductor installation. It is concluded that the parallel cable installation without proper cable rephrasing derates the cables significantly. The third-order harmonic current can cause a significant reduction of the current rating if its distortion is over 30%.