JEE_V2_N4_RP9 E. Vidya Sagar P.V.N. Prasad Journal on Electrical Engineering 2230 – 7176 2 4 71 77 Distribution Substation, Distribution System, Minimal Cut-Set, Non-Radial, Reliability Indices In this paper a composite reliability evaluation of a practical distribution system is developed. The reliability of a substation is calculated using minimal cut-set technique. The interaction between distribution substation and primary distribution system is modeled according to the tripping behavior of feeder circuit breakers. Then, the contribution of reliability indices evaluated from the primary distribution system is added to the previous two effects. The primary indices (ë, r, U) and the secondary reliability indices such as customer oriented and load-energy oriented indices are calculated for four types of distribution configurations. The developed models reflect the effect of distribution substations, primary distribution systems, and the interaction between them. Comparisons of reliability indices are made. April - June 2009 Copyright © 2009 i-manager publications. All rights reserved. i-manager Publications http://www.imanagerpublications.com/Article.aspx?ArticleId=223