The method of symmetrical components is a powerful tool for understanding and determining unbalanced currents and voltages in threephase electrical power systems. In a sense it is the “language” of those associated with relay protection. For almost all faults, the intolerable conditions that require isolation of the problem area involve unbalances. Thus the quantities that operate the protection are directly or indirectly related to symmetrical components.
This book presents the fundamental concepts of symmetrical components along with a review of per unit (percent), phasors, and polarity. Typical examples are solved throughout the text, and an additional problem section is included for further studies. The book is intended as a text for students and as a reference manual for practicing engineers and technicians-all who are involved or associated with relaying and power system analysis. The modern computer provides large volumes of fault and related data but without any understanding or appreciation.
Thus the aim of this book is to provide
(1) a practical understanding of system unbalances, the basic circuits, and calculations,
(2) the techniques of making calculations when a computer or program is unavailable,
(3) an overview for visualization of faults, unbalances, and the sequence quantities,
(4) the determination of system parameters for manual calculations or computer programs. This text has been developed from notes used over many years of presenting symmetrical components.
Originally they were based on the classic book by Wagner and Evans, Symmetrical Components (1933). Associates, students and friends within Westinghouse, the IEEE, CIGRE, many utilities, and industrial and consulting companies around the world have directly or indirectly added contributions over the last fifty-five years. Special thanks are extended to William M. Strang for his great work on the figures and to Ruth A. Dawe and Lila Harris, Marcel Dekker, Inc., editors, for their wonderful assistance and encouragement.
Download Symmetrical Components for Power Systems Engineering by J. lewis Blackburn easily in PDF format for free.