STATIC POLYPHASE DISTANCE RELAY SCHEME FOR THE PROTECTION OF TRANSMISSION LINES

Abstract

Chapter I deals with the relay elements and comparstors used in modern protective relay schemes- Phase and amplitude comparators using transistors, rectifiers and Hall multipliers are reviewed in brief. Chapter II deals with the development of polyphase relay schemes. It gives the development of polyphase relays an^ reduction of distance relay and directional relay in protection schemes in brief, polyphase distance relay using phase comparison and polyphase distance relay using amplitude oomparison have been discussed in more detail. Chapter III deals mainly with the author's own work in the field of static polyphase distance relay scheme. Two schemes are developed ( l) based on the principle of phase comparison (2) based on the principle of phase sequence measurement by logic circuits. The first was found unsatisfactory therefore the second scheme has been described in detail as regard to its characteristic on single phase to-ground, ph as e -t<j -phase and double phaseto- ground faults. Two schemes have also been proposed to protect the line against 3 -phase faults. Chapter IV deals with the experimental set up of the scheme based on the principle of phase sequence measure ment. Two similar units wore developed in order to avoid the over-reaching of the relay on d.c, transient in the fault current. Chapter V gives the experimental results on steady state and dynamic performance of the relay under fault condi tions on positive as well as negative transients