Reliability Worth Guides Distribution System Design

Methods are presented for determining the optimum choice between alternative distribution systems based on the minimum sum of the initial investment and the capitalized cost of maintenance and power failure. Special consideration is given to 1) inclusion of maintainability factor, 2) evaluation of an incomplete redundant system, 3) delta-Y transformation method of reliability analysis of a complex network. A typical case-study of evaluating five alternative designs is included to illustrate step-by-step application of the methods. The optimum choice changes from one system to another as the undelivered energy charge rate varies.