<b>Primary causes of voltage fluctuations that affect industrial optical sorters. </b> <b>A quasi-experimental study.</b><b></b>

Background: The study aimed to identify the primary causes of voltage fluctuations that affect the industrial optical sorter. Methodology: This study adopted a quantitative quasi-experimental design at the ACPCU factory in Uganda to evaluate the impact of voltage fluctuations on a Satake NRM3 optical sorter. Data from a Fluke 435-II analyzer was synchronized with production logs and environmental data over 24 days. The methodology employed FMEA to identify failure modes, alongside Probabilistic Risk Assessment and Monte Carlo simulations to quantify downtime and techno-financial losses, with analysis performed in Excel, MATLAB, and SPSS. Results: Analysis of 241 tagged disturbance events over 24 days reveals that internal operations are the primary drivers of voltage instability at ACPCU Ltd. Load switching (40.2%, n=97) and high-power machinery (32%, n=77) collectively account for 72.2% of all fluctuations, primarily due to large inrush currents and simultaneous motor starts. External factors proved less frequent: surges contributed 14.1% (n=34), while grid instability and heavy rains accounted for 6.7% (n=16) and 5.8% (n=14) respectively. The dominance of internal causes over external grid faults underscores significant local power quality challenges. Specifically, transient dips often coincided with the operation of hullers and aspiration fans. Minimal disruptions were linked to loose wiring (1.2%). These statistics suggest that implementing soft-start mechanisms and staggered motor sequencing could mitigate over 70% of recorded disturbances, significantly stabilizing the 415/240V supply network for the optical sorter. Conclusion: Voltage fluctuations affecting the optical sorter are predominantly caused by internal factory conditions, particularly load switching, loose connections, and phase imbalance. Recommendation: Implement harmonic filtering, load balancing, and routine maintenance to minimize internally generated voltage disturbances.