Chapter 14 - Short-Circuit Analysis

Abstract

In this chapter per-unit quantities, percentage values and short-circuit kVA are defined and explained. The importance of short-circuit current calculation is discussed. Oscilograms of short-circuit currents, electrical torque, and field current following a symmetrical short circuit at the terminals of an unloaded salient pole synchronous machine are given. The role of current limiting reactors, viz., generator reactors, feeder reactors, and bus-bar reactors, is explained with reference to their construction, location, and relative advantages and disadvantages. The effect of load current or prefault current on short-circuit current is detailed. Single-line reactance diagrams are used for estimating the short-circuit current. The need for network reduction is emphasized through several worked-out examples