Calculating Short-Circuit Currents with Contributions from Induction Motors

Chapter 7 of a forthcoming book, Recommended Methods for Calculating AC Short-Circuit Currents in Industrial and Commercial Power Systems (IEEE Violet Book) is discussed. The book will be one of the IEEE Standards Board ``Color Book´´ series of Recommended Practices prepared by the Industrial Power Systems Department of the IEEE Industry Applications Society. (It is being developed under IEEE Project Authorization P551.) The chapter describes the nature of induction motor short-circuit current contributions, discusses calculating techniques, and examines the simplified methods of accounting for induction motor contributions described in ANSI C37 Circuit Breaker Standard Application Guides. An extension of these simplified methods is recommended to eliminate the possible need for duplication of calculations. Examples of calculations are included. For this chapter, it is assumed that other chapters in the ``IEEE Violet Book´´ cover the purpose of short-circuit calculations, calculating methods available, and details of calculations involving passive power system components and synchronous machines.