Case study: Achieving selectivity on a critical distribution network

In a metropolitan area, American Electric Power operates a complex, looped distribution network that consists of several parallel circuits between a single-source substation and two load-serving substations. The purpose of this loop is to maintain service reliability when a number of the parallel circuits are out of service. Because fault current contributions vary greatly depending upon fault location, this operating configuration presented a challenge to the design and setting of a protection system that was selective for faults on the network. This paper presents the advanced solutions implemented for the protection of this crucial network.