Coordination-Free Ground-Fault Detection for Mine Distribution Systems

A ground-fault relaying scheme is presented that is intended to eliminate the need for time-delay relays for ground-fault detection on mine electrical distribution systems. The concept is based on pilot-relaying logic, and existing ground-check and grounding conductors are used to convey ground-fault information between adjacent relay units. The new scheme should not add any additional work during the installation of mine power systems and should minimize the expertise needed for power-system operation. To illustrate this concept, the design and development of the new relaying system is presented. The performance of a prototype relay during laboratory simulations is also given. Although the work is projected at underground coal mining, the relay appears feasible for any extensive radial distribution system.