A high-speed two-stage phase comparator

Abstract

The paper reports further work on phase-comparison techniques by the same authors. The technique reported here describes the operation of a double-input phase comparator based on a two-stage phase-comparison process between two relaying signals used to measure the phase difference between them, and hence it can be applied to either the phase-comparison carrier or distance protection systems. The comparator reduces the maximum operating time to a value corresponding to half the trip angle of the system. An example is given of its application to a mho characteristic distance relay when applied to protect a typical 40 km, 132 kV single-circuit transposed line.