The effects of cable capacitance on longwall power systems.
Novak-T; Basar-J; Sottile-J; Kohler-JL
IEEE Trans Ind Appl 2004 Sep/Oct; 40(5):1406-1412
Utilization voltages used on longwall equipment operating in U.S. coal mines have increased steadily over the past 15 years from 1,000 V to 4,160 V. This voltage increase has directly influenced the 200% gain in overall longwall productivity from 1987 to the present. The transition from medium voltage (661 V-1,000 V) to high voltage (>1,000 V) has permitted significant increases in face widths and equipment sizes. Longwall systems with total connected loads of over 5,000 hp are now common, and all U.S. longwalls now use high-voltage equipment, with most using 4,160 V. Shielded cables, which have significantly more capacitance than unshielded cables, are required for high-voltage applications in the mining industry. This capacitance can have detrimental influences on system overvoltages and relay selectivity during ground-fault conditions if the values for the grounding resistor and the ground-fault-relay pickup settings are improperly chosen. These issues are addressed in this paper.
Electrical-systems; Ground-fault-relaying; High-resistance-grounding; Longwall-mining; Mining-equipment; Mining-industry; Coal-mining; Electricity; Hazards; Safety-research; Electrical-safety
NIOSH Pittsburgh Research Laboratory, P.O. Box 18070, Pittsburgh, PA 15236
IEEE Transactions on Industry Applications