A Practical Condition-Based Maintenance Framework for ۱۵۰۰ V DC Overhead Contact Systems: A Case Study of Shiraz Metro

Maintenance of DC overhead contact systems (OCS) in metro networks faces a persistent trade-off between the need for extensive inspection coverage and limited human and operational resources for timely intervention. In Shiraz Metro, a preventive maintenance (PM) program comprising ۹۲ defined activities is currently implemented; however, no quantitative mechanism exists to convert inspection findings into repair priorities based on actual asset condition and location criticality. This paper proposes a practical three-layer framework consisting of a Condition Index (CI), a Location Criticality Index (CR), and a Maintenance Priority Index (MPI). Initial weights are derived from the requirements of EN ۵۰۱۱۹ and the principles of the RAMS framework (EN ۵۰۱۲۶) and are explicitly presented as provisional coefficients. Two real mechanical failures of the tensioning system (occurring in ۲۰۲۰ and ۲۰۲۵) are analyzed as representative low-probability, high-consequence events. Available measurements of insulation resistance and the multi-year trend of section-insulator contact resistance are presented as evidence that quantitative parameters already exist and can be directly incorporated into the model. Without discarding the existing PM program, the proposed framework adds a condition-based decision layer and outlines a gradual, low-cost pathway towards condition-based maintenance under data-scarce conditions.

کلیدواژه ها:

Condition-based maintenance ، DC overhead contact system ، Maintenance priority index ، Tensioning system ، Shiraz Metro