TECHNOLOGICAL INNOVATIONS IN DEEP COAL-MINE POWER-SYSTEMS

Various innovations and changes have occurred to underground coal mine power systems during the past ten years. Some of these are the use of higher utilization and distribution voltages and associated switchgea r, the use of programmable logic controllers (PLC's) for control, moni toring, and diagnostic applications, improved protective relaying with built-in test circuitry, power-factor correction near loads for impro ved voltage regulation, and modifications to power-system component ar rangement. Many of the innovations were necessitated by significant in creases in power requirements of face equipment, particularly longwall equipment, while others are the result of improved technology, In eit her case, improved power-system operating characteristics, as well as enhanced levels of safety, have resulted. This paper describes many of the major innovations that have evolved during recent years.