Combined phase and ground distance relaying

ANEW relaying system provides complete phase- and ground-distance relaying protection for transmission lines. It features a reduction in the necessary equipment usually applied where three relays are connected to protect against faults involving 2- or 3-phase conductors, and where three relays are connected to protect against single-phase-to-ground faults. The reduction in equipment is achieved by causing the directional starting unit of the ground-distance relay to perform the double duty of detecting faults of a phase nature as well as faults of a ground nature.