Graphical methods, design considerations, practical circuits and test results of multi-input sine comparators.

This paper presents the graphical analysis and design considerations of multi-input sine comparators whose mathematical analysis has already been presented in an earlier paper by the authors (Anti Kumar and Parthasarathy 1967). Particular emphasis is placed on the design of a circuit, using semiconductor components, which provides a quadrilateral polar characteristic on the impedance plane. Novelties of design include a reactance reach, increased tolerance to fault resistance as the fault point moves towards the relay location, directional feature and independent control of each line segment constituting the quadrilateral, so that the fault area and tho relay characteristic could be closely matched. Test results show the negligible transient overreach and a constant operating time which is 1 1/2 cycles or less, and irrespective of fault location. The flexibility of design enables it to be used as a three-zone stepped time-distance relay or in conjunction with pilot schemes.
Test results show the versatility of the unit and the flexibility of the comparator theory. By suitable modifications of only the input signals, any desired characteristics can be easily obtained as dictated by system requirements. Special care has been taken to use similar switching blocks so that replacement is rendered simple. [ABSTRACT FROM AUTHOR]