Reliability model for the optimal replacement of shovel cables

A reliability model has been developed for the optimal replacement of minin g shovel cables on the basis of adherence to a replacement policy governed by number of hours. Change-out times are determined that minimize the expec ted cost per operating hour for cable replacements. The model is generic in nature and can be applied to non-repairable components subject to wear tha t have high capital and installation costs and do not lend themselves to co ntinuous condition monitoring. The model incorporates the effect of periodi c inspections and provides a methodology for the calculation of confidence intervals associated with replacement times and hourly operating costs. The model was applied to calculate optimum replacement times for the hoist, crowd and retract cables of three BE 295 shovels at Quebrada Blanca mine, northern Chile. The results show that implementation of an hours-based repl acement policy can bring economic benefit. The magnitude of the benefit and the financial risk of implementing the policy depend on the cost premium a ssociated with unplanned replacements and the percentage of unplanned repla cements currently performed at the mine. Further development of the model may render it suitable for determining the optimum replacement intervals for turbo-charger units in haul-truck engine s.