Zone-Packaged Ground Distance Relay: I - Principles of Operation

A novel basis has been developed for designing distance relays that will detect ground (earth) faults in a preset zone of transmission lines. The fundamental basis is described, and the relay performance is analyzed mathematically over a wide range of power-system conditions to show its constancy of reach and proper sense of direction. A relay designed on this basis can be zone-packaged and is inherently directional.