Mining Publication: Detection of Downed Trolley Lines Using Arc Signature Analysis

A cost effective and practical system for monitoring hauling system electrical current patterns was developed. The aim was to reduce the hazards associated with electrical fault currents from fallen coal mining trolley hauling system lines. The current could result in local heating or arcing and thus increase the risk of a fire. Computerized electrical current analysis techniques were tested at several Pennsylvania coal mining sites on mining trolley hauling systems using a range of currents. Current readings were taken during all phases of the loading process, under normal (light, intermediate and heavy traffic) and during simulated arcing and bolted fault conditions. Voltage data collected from these trials were used to develop a microprocessor based fault detection algorithm, which field tests showed was 95% accurate. The frequency of the rectifier current and the imposed fault signal were used to detect arcing faults. The authors conclude that this improves the detection and extinguishing of self sustaining arcs thus minimizing fire risk.