This book describes the fundamental principles governing electromagnetic transients. In the opening chapters (1 to 5), it presents basic concepts of electrical circuits and linear systems. Chapters 6 and 7 discuss the fundamental concepts of wave propagation in single-phase and multiphase transmission lines, and introduce, in Chapter 8, the most efficient numerical method applied in electromagnetic transient programs. Chapter 9 describes the representation of frequency dependent parameters of transmission lines. Chapters 10 to 12 address the basic overvoltages in power systems. Chapters 13 and 14 approach some basic transients with Shunt-capacitors and Series-capacitors. Topics concerning the opening of circuit breakers are also addressed regarding transient recovery voltages (TRV) in Chapter 15. Chapter 16 summarizes information on the behavior of the electric arc. Chapter 17 supplements the chapters that address overvoltages in relation to the engineering procedures used to establish the insulation levels for equipment. The book concludes in Chapter 18 with a study of surge arresters.