Transient Analysis of Alternating Current Machinery

It is now thirty-five years since Fortescue devised the method of symmetrical components for analysing the unbalanced operation of a polyphase induction machine.

Since then several textbooks and many technical papers devoted entirely to the application of the method to a variety of engineering problems have been published. All these applications concerned the steady-state behaviour of the machines and connected systems, and the resolution into symmetrical components involved the complex representations of the alternating currents and potentials and the system constants. Although Fortescue was aware that his method of resolution could also be applied to the instantaneous values of currents and potentials, no systematic development of this phase of the analysis has yet been given.

This book is the result of a course of lectures and conferences given to graduate students during the past ten or twelve years. It shows how the method of symmetrical components can be used to determine the transient behaviour of polyphase machines under different operating conditions. The symmetrical components of 3-phase instantaneous currents, steady or transient, are time-variable complex quantities, and each consists of one or more rotating vectors, depending on the operating condition being discussed.