Abridgment of directional ground relays

Abstract

Less than four years ago there appeared the following summary of protective relay practise for transmission systems: “Electrical faults on a transmission or distribution system consist mainly of short circuits and grounds. The protective scheme is primarily designed to operate on values of current caused by short circuits between phases…. If the neutral of the system is grounded, the method of grounding has an important bearing on the protective scheme. Where the neutral system is dead grounded, or grounded by means of a low resistance, the protective scheme designed to operate on short circuit usually also protects against grounds.”