Application of 4160 V to longwall face equipment

Since the introduction of longwall mining in the United States, continuous developments and improvements of face equipment have occurred. These developments have caused a trend toward high-capacity longwalls with face widths of 1000 ft. This evolution of longwall equipment has resulted in significant increases in power requirements such that the combined horsepower for the face conveyor, shearer, stage loader, crusher, and hydraulic pumps can now exceed 5000 hp. With increased power requirements, the traditional utilization voltage of 995 V became inadequate for many applications, resulting in an initial trend toward 2400 V. But power requirements have continued to grow, and the present trend is toward the use of 4160 V as a longwall utilization voltage. This paper discusses the design of a 4160-V system and compares some of its operational characteristics with those of a similar 2400-V.