PREFACE TO FOURTH EDITION
SOME thirty years ago and well-known electrical engineer was ordered by his I physician to take a complete rest. During this period, as a diversion, he began to study transmission-line calculations. Out of that came, in 1922, a book that was quickly recognized as a classic on the subject because it was simple, practical, useful. The man was William Nesbit; the book, "Electrical Characteristics of Transmission Circuits."
In the two succeeding decades power-transmission systems grew tremendously in complexity. Voltages were doubled, longer lines were built, interconnections became more extensive, knowledge of how to protect against lightning was greatly increased, and new methods of calculating performances were adopted. With all this grew the need for a new book on transmission lines, one of broader scope that would meet the new conditions, but retain the entirely practical viewpoint of its predecessor. Fourteen men, all connected with the Central Station Engineering Group of the Westinghouse Electric Corporation, undertook to produce such a book. All of these men worked daily on actual problems such as are considered here. With this background of experience and with the reputation of the Nesbit book as inspiration, they presented in January, 1942 the first edition of a book which they hoped would be useful to all concerned with electric-power transmission as a practical reference book, helpful in solving everyday problems.
In 1943 á second edition was brought out in which two chapters that discussed the general features of the electrical distribution problem were added at the end of the book. The third edition differed from the second edition only in that the two chapters were introduced just before the appendix.
A fourth and completely rewritten edition is presented herewith. It contains essentially the material of the previous three editions, sometimes with new authors, and three new chapters—Excitation Systems, Application of Capacitors to Power Systems, and Power Line Carrier Application. As before, all of the authors are from the Central Station Section or are closely associated with it. As was the case with previous editions, this one also bears the imprint of two outstanding engineers, who contributed so much to the transmission of power. Dr. Charles L. Fortescue and Mr. Robert D. Evans. The latter, before his recent death, was one of the active participants in the previous editions. The name or names of the original authors and the revising authors appear at the head of each chapter.