Overall Cost Comparison Between Cable and Overhead Lines Including the Costs for Repair After Random Failures

This paper deals with the comparison between the overall whole-of-life costs of overhead lines (OHL) and those of underground insulated cables (UGC). Almost all the investigations published so far, when analyzing maintainability issues, take into account only the costs of planned/periodical maintenance; here, a method for assessing also the expenses sustained for repair after random failures is proposed. The number of random failure events for each kind of component over the entire service life of a transmission line can only be predicted on a probabilistic basis: its expected value is estimated by making use of the relevant mean failure rates from recent statistical surveys. The entire procedure is shown by carrying out a particular case study as an example; the break-even point between the OHL-UGC overall costs, corresponding to a typical rural land Italian market value wx= 26.9 €/m2, is identified. Nonetheless, the method may be widely applied to any type of OHL–UGC comparison.