Digital protection is based on the use of computers in power line relaying. Since the late 1960s@ digital devices and techniques have been applied to almost all new protection schemes. Today the technology is moving towards standardised hardware platforms; at the software level@ however@ there remains a huge variety in approaches and protection algorithms. This book gives a fairly detailed understanding of the principles and techniques underlying the application of digital technology and algorithms to protection. It avoids going into detail of specific products: up-to-date information on these is available from the manufacturers. Instead it aims to give the reader a thorough understanding of the generic problems of digital protection. The text covers the mathematical basis of numerical techniques and relay algorithms@ the basic elements of digital protection and the fundamentals underlying the commonest algorithmic forms@ particularly as applied to line protection. It deals with the fundamentals of travelling-wave techniques and their application to transmission lines@ and with digital differential protection of transformers and lines. Author(s) A. T. Johns@ S. K. Salman