Randomised Field Trial of Power-Distribution System Reliability: A Methodological Evaluation of Equipment in Rwanda

"background": "Reliable power distribution is critical for economic development, yet many low- and middle-income countries face persistent challenges with system reliability. There is a paucity of rigorous field-based methodologies for evaluating the performance of distribution equipment in real-world, low-resource settings. ", "purpose and objectives": "This study aimed to develop and implement a novel randomised field trial methodology to empirically evaluate the reliability of different power-distribution equipment configurations within a national grid. The primary objective was to quantify failure rates and mean time between failures for selected apparatus. ", "methodology": "A stratified randomised controlled trial was conducted across multiple regions. Newly installed transformers, circuit breakers, and surge arrestors from three different manufacturers were randomly allocated to 150 rural and peri-urban substations. Performance was monitored via remote sensors and manual inspections. Reliability was modelled using a Weibull survival analysis: h (t) = \\{\ \ (\ \) ^\-1, where h (t) is the hazard function, \ is the scale parameter, and \ is the shape parameter. Robust standard errors were calculated to account for clustering. ", "findings": "Equipment from Manufacturer B demonstrated a 34% lower hazard rate for catastrophic failure compared to the other two suppliers (95% CI: 22% to 45%). The shape parameter \ was estimated at 1. 8, indicating an increasing failure rate over time for all groups. Surge arrestor failure was the most common initiating event for cascading faults. ", "conclusion": "The randomised trial proved a viable method for obtaining high-quality comparative reliability data in a field setting. Significant variation in equipment performance was identified, which has direct implications for procurement and lifecycle costing. ", "recommendations": "Utilities should incorporate randomised field testing into procurement validation processes. Specifications should be updated to require evidence from in-country operational environments, with a focus on surge protection resilience. ",