Most technical universities in the world, which offer power systems courses, offer protection as a main stream topic. A good text book which covers existing and emerging techniques will be important, popular and timely. This book will be an important contribution to the future integrated Smart Transmission and Distribution Grid. This book provides up-to-date information on conventional protection schemes. It introduces new trends such as the protection of distributed generation, digital equipment for protection, and wide area and adaptive protection concepts. It also provides worked examples, review questions and problems and answers to further student understanding. This book is structured to first provide a comprehensive guide to protection principles, moving into digital systems and equipment used for modern protection schemes, and finally discussing the new protection paradigms that are emerging due to the application of Synchronized Measurement Technology, involving Phasor Measurement Units, Data Concentrators and new Wide Area Monitoring, Protection and Control (WAMPAC) applications. The first part of this book provides a detailed treatment of protection principles supported by worked examples, review questions and problems. Further, it discusses the issues and new paradigms in protection that are resulted from the addition of the new form of generators to the power system, such as wind, PV and other distributed generation. As the industry trend is migrating to more digital protection equipment, the second part of this book provides comprehensive treatment to Intelligent Electronic Devices IEDs, their applications and communication requirements. Finally the third part offers a detailed discussion of the application of Phasor Measurement Units to the power system, particularly wide area approaches (WAMPAC).