SDG-1T, SDG-2T, SDG-4T Static Ground Distance Relay Instruction Leaflet

This document provides application, fundamental theory, and construction details for single-zone ground distance relays (SDG-1T, 2T, 4T) used to detect faults on subtransmission or transmission lines. It covers distance measurement principles for ground faults, including zero-sequence compensation, phase-to-phase desensitization, and the operation of compensators and magnitude comparison circuits.