Utilization voltages used on longwall equipment operating in coal mines in the United States have increased steadily over the past 15 years from 1000 up to 4160 V. This voltage increase has directly influenced the 200% gain in overall longwall productivity from 1987 to the present. The transition from medium voltage (661-1000 V) to high voltage (greater than 1000 V) has permitted significant increases in mining face widths and equipment sizes. Longwall systems with total connected loads of over 5000 hp are now common, and all longwalls in the United States now use high-voltage equipment, with the majority utilizing 4160 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 neutral grounding resistor and the ground-fault-relay pickup settings are improperly chosen. These issues are addressed in this paper.
|Number of pages||7|
|Journal||IEEE Transactions on Industry Applications|
|State||Published - Sep 2004|
Bibliographical noteFunding Information:
Paper PID-04-17, presented at the 2003 Industry Applications Society Annual Meeting, Salt Lake City, UT, October 12–16, and approved for publication in the IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS by the Mining Industry Committee of the IEEE Industry Applications Society. Manuscript submitted for review October 15, 2003 and released for publication June 25, 2004. This work was supported by the Pittsburgh Research Laboratory, National Institute of Occupational Safety and Health (NIOSH), under Contract 200-2002-000589, Reduction of Mining Electrical Hazards Through Improved Engineering Controls.
ASJC Scopus subject areas
- Control and Systems Engineering
- Industrial and Manufacturing Engineering
- Electrical and Electronic Engineering