Sensitive ground protection for transmission lines and distribution feeders

If ground fault coils are used in high tension overhead systems and underground cable networks, earth leakage relays may be employed to indicate the location of single ground faults. The influence of the contact resistance at the point of the ground is explained. Earth leakage relays in compensated networks, their operation in radial and meshed networks, and the means for determining their correct operation by tests, are described. The paper is based on the practical experiences gained from such installations in England and in Continental Europe.