Setting response of generalised comparators for distance protection

In distance protection, the magnitude of the signals from which measurements are made are subject to wide variation according to system operating and fault conditions. The necessity to preserve protective integrity precludes the use of comparator circuits with extreme sensitivities, and some deterioration in performance occurs near the setting. The paper examines the setting response of generalised phase comparators, the principles of which have been outlined in other papers. Criteria for optimising responses are given, and it is shown that the new device is inherently very accurate. The paper concludes by comparing the response with that of a practical alternative.