Numerical relays are based on the use of microprocessors. The first numerical relays were released in 1985. A big difference between conventional electromechanical and static relays is how the relays are wired. Electromechanical and static relays have fixed wiring and the setting is manual. Numeric relays, on the other hand, are programmable relays where the characteristics and behavior can be programmed. Most numerical relays are also multifunctional. Scope.
Modern protection relays. Multifunctional protection Product benefits. Provide continuity of power to consuments. Protection of network assets. Protection against life-threatening electrical incidents Product features. Self-checking facility.
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Low burden relays improve accuracy. Fast fiber optical communication with substation LAN.
Adaptive relaying schemes. Permit storage of historical data. Time stamping.
The death of Professor Arthur Wright in the summer of 1996 deprived me of a friend and a colleague whose judgement and experience shaped this book. I pay tribute to his contributions to protection and electrical engineering education. In the five years since the first edition appeared, many developments have taken place and it is now necessary to update the book.
The use of digital communications and advanced signal processing techniques is now widespread and several fully numeric relays are available from manu足 facturers. Two new Chapters 13 and 14 have been added to introduce readers to these concepts and associated techniques. Artificial intelligence is making its impact in all engineering applications and power system protection is no exception.
Expert systems, fuzzy logic, artificial neural networks, adaptive and integrated protection, synchronized measurements using the global positioning system, genetic algorithms, flexible a.c. Transmission systems, are some of the techniques considered in connection with protection. Although many of these techniques have not yet found major application in protection, it is nevertheless essential for the educated protection engineer to have a basic understanding of the underlying principles and methodology so that he, or she, can evaluate their suitability for new relaying problems and applications. Chapter 15 was therefore added to guide readers through this developing area. I have also added some new material in other chapters to reflect changes over the past years.