A distance relay with adjustable phase-angle discrimination

DISTANCE-TYPE transmission-line relays have been used very successfully for a number of years. Several different distance-type characteristics have been available. Among these characteristics are the impedance relay which measures impedance substantially independent of the phase angle, the reactance relay which responds only to the reactive component of the impedance, and a third characteristic which responds to a compromise between pure impedance and reactance. Another type of relay characteristic which combines impedance measurement with a directional indication has been used for a number of years as a fault-detector element to supervise another distance-measuring element.