A Multiprocessor-Based Distance Relay: Design Features And Test Results

This paper describes the prototype of a multiprocessor-based distance protection system for transmission lines. It explains the general structure of the eight parallel microprocessors, analog and digital interface and some of the hardware particularities. The relaying functions include impedance, overcurrent, overvoltage, line check and other algorithms. Also described are special features such as autocalibration, display, and local/remote monitoring The availability reliability and security aspects of the system are discussed. Finally, laboratory test results are reported.