Mine Electrical Power Systems. Transients Protection, Reliability Investigation, and Safety Testing of Mine Electrical Power Systems. Vol. II--reliability of Mine Electrical Power Systems.
This report describes a comprehensive program of research into the reliability of mine electrical power system components and the resultant reliability of the total system. The analytical work included definitions of terms, fail rate functions and distributions, failure rate estimation and techniques, and procedures for theoretical reliability assessment. One of the primary mine power system components was the ac-molded case circuit breaker. This device is known to have low reliability and hence an unfavorable impact on mine safety and productivity. Ac-molded case circuit breaker reliability was studied analytically, laboratory tested, and field monitored. A similar three-pronged effort was made to study the reliability of undervoltage relays-releases. Particular emphasis was placed on new solid-state undervoltage relays. The reliability of bulk power components, such as trailing cables, motors, control gear, and other equipment, was assessed by gathering maintenance records from active mines. The work was extended to include the reliability, availability, maintainability, and safety of these components.