This handbook on power systems consists of a set of 4 volumes. These books are carefully planned and designed to provide the state of art material on major aspects of electrical power systems, short-circuit currents, load flow, harmonics and protective relaying. Many aspects of power systems are transparent between different types of studies and analyses; knowledge of short-circuit currents and symmetrical component is required for protective relaying, and fundamental frequency load flow is required for harmonic analysis. Currently, power systems, large or small, are analyzed on digital computers with appropriate software. However, it is necessary to understand the theory and basis of these calculations to debug and decipher the results. The material is organized with sound theoretical base, practical applications, and case studies based on the author?s 45+ years of experience with real world problems.