Online digital fault locator for overhead transmission line

The ability to determine quickly and accurately where faults have occured on a transmission line has long been an operating man´s dream. This paper describes a completely digitalised online fault locator which takes input signals from existing c.t.s and p.t.s and works on a reactance-ratio-measurement principle. It operates in less than two cycles from the instant that the relay delivers a trip output, and is therefore capable of locating transient as well as permanent short-circuit faults. Furthermore, a suitable compensation in fault-locator inputs is proposed which results in increased resistive coverage for the suggested fault locator when applied to double-end feed lines.