Microprocessor-based protection relays: design and application examples

How microprocessor-based feeder protection relays, through use of such features as programmable curve shape and time delays, allow economical, yet accurate coordination of distribution systems is discussed. The design of typical microprocessor-based relays is discussed. An overview of some of the features provided by such designs and some specific application examples are presented. A discussion of the most common problems associated with these relays is given