Parameters affecting economic selection of cable sizes

The evaluation of power cable costs considers the present worth of funds required for a new cable installation. Two components make up this cost, first the initial investment cost, and second, the cost of losses ever the life of the cable. Generally, for a given voltage class, the capital investment component increases as the conductor size increases. Conversely the losses decrease as conductor size increases. Selection of cable size is currently based on ampacity considerations; that is, a cable with a minimum acceptable cross-sectional area is usually selected without consideration of the cost of the losses that will occur during the life of the cable. Since the cost of losses over the lifetime of the cable may require substantial selection of a larger conductor size than required, ampacity consideration will often result in smaller value of losses and, hence, may lead to a lower overall cost. A number of examples which demonstrate sensitivity of the conductor cross-section and overall cost to variations in key parameters of the model are presented in the paper