The objective of writing this book continues to be to provide the reader with a text that presents a lucid and comprehensive treatment of transformers and more common types of rotating electrical machines. The philosophy of the book is to emphasize the physical understanding of the basic principles underlaying the operation of electrical machines. In the order to achieve this goal, the theory is developed from elementary ideas in such a style that their physical concepts are highlighted. The magnetic flux viewpoint has been employed througout this book, as these approach provides a deep insight into the internal behaviour of electrical machines are important, because these concepts only show the way to creative engineering and become the most valuable asset of student's education. Each chapter takes off from the first fundamentals and is so developed progressively that an appropriate use of illustrative figures and a wide variety of worked examples. Each chapter concludes with numerous unsolved problems with answers, conceptual questions and hints to the relatively difficult ones.