Principles and Practices of Relaying in the United States

The rapid growth in power system size and interconnection over the past 30 years has greatly increased the problem of isolating faults. Standards of service have increased, making necessary greater reliability, and higher speed of operation. Innumerable relaying devices and schemes have been developed to meet the more exacting requirements. Some have been designed for special situations and others apply to basic situations which occur on many systems. It is these latter which it is hoped to discuss in this paper.