The digital Distance Protection is the name given to the Protection ,which is selective and extremely fast Protection of Overhead Transmission lines and Cables.
Distance Relay action and its application depends on the distance of the feeding point to the fault in overhead Transmission lines and cables with single- and multi-ended in feeds in radial, ring or any type of meshed systems at different voltage levels. The network neutral can be earthed, compensated or isolated.
Distance Protection Relay respond to the two fundamental parameter Current(I) and Voltage(V), i.e, impedance at the Relay location. The value of impedance is fairly constant so such type of relay respond in distance between Fault location and Relay location.its performance is depend upon the ratio of Current and Voltage.