Determination of Total Resistive Loss in a Multiple Circuit, Three-Phase Cable System

An analytical approach is presented for estimating the total resistive loss in the randomly positioned conductors of a multiple circuit, three-phase cable system, as in a duct bank. By breaking the total resistive loss into three components, i.e., skin effect loss and two independent proximity effect losses, the problem is simplified so that each loss component can be computed separately. A semi-empirical formula for determining the proximity effect loss from a single external source current is established, which is the building block for solving the total proximity effect loss. For a typical three-phase duct bank scenario, the proposed approach achieves good agreement in predicting the total resistive loss when compared to finite-element analysis simulations.