Sensitive Ground-Fault Protection for Mines. Phase 1. Alternating-Current Utilization

摘要

The report concerns the research and development of sensitive ground-fault relays for ac utilization systems in mining. Sensitive relaying employs very low pickup levels such that, when used in conjunction with very high resistance grounding, the exposure of a human to ventricular fibrillation is significantly reduced. To delineate the desired relay characteristics, the report commences by reviewing and updating previous research in this area. The critical relay component for sensitive ground-fault relays has been found to be the current transformer; their theory and design are detailed. Electronics for two prototype relays have been produced through the research and information is presented so that either may be duplicated.