In the second edition of this proven textbook and reference work for study and further education, significant updates have been incorporated. The subject matter is protection technology in the entire field of electrical power engineering. Contents include: Fundamentals of protection technology: introduction, typical types of faults, important fault detection criteria, measuring transformers for protection purposes, voltage transformers, analog protection technology: static protection relays and protection systems, practical application of fault detection criteria, analog network and plant protection, analog machine protection, digital protection technology: computer-based protection and control technology, conversion of analog quantities into digital signals, digital signal processing, measurement algorithms, logical structures of digital protection devices.