Threshold and Dynamic Characteristics of Relays Using Multiple-Input Comparators

In this paper mode of operation of multiple-input moving-coil relay with fully rectified inputs, transistor block average phase comparator and rectifier bridge amplitude comparator are analysed. Methods for obtaining special threshold characteristics of elliptical, hyperbolic, etc. form and composite threshold characteristics formed by the intersection of straight lines, circles, etc. are shown and examples given. In each case the inherent dynamic performance of the relay, in relation to power system conditions, is determined in order to see its suitability for application.