Impact of Voltage Fluctuations on the Performance of Domestic Water Pumps

Abstract

Electricity distribution networks often experience voltage fluctuations and severe voltage drops, which can adversely affect the performance and reliability of domestic water-pumping systems. These voltage disturbances may result in reduced hydraulic performance, increased energy consumption, and disruptions in water delivery. This study investigates the effects of voltage fluctuations on the performance, efficiency, and operational reliability of a standard 0.5 horsepower HP, single-phase induction-motor-driven centrifugal water pump. Experimental data, including RMS voltage, current, flow rate, pumping head, and motor rotational speed, were recorded over a 500-second operating cycle. The measured field data were compared with those obtained from an idealized constant-power theoretical model. The experimental results indicate that voltage drops below the nominal operating level are associated with significant degradation in pump performance. Under the constant-power assumption, a decrease in supply voltage causes an increase in line current, thereby increasing stator copper losses and imposing greater thermal stress on the motor. Undervoltage conditions also reduce the motor's electromagnetic torque capability and can increase motor slip, resulting in reduced rotational speed. The resulting reduction in motor speed is accompanied by decreases in volumetric flow rate and pumping head, leading to a reduction in overall pump efficiency. In addition, an empirical second-order polynomial model was developed to characterize the relationship between water flow rate and supply voltage. The model accurately quantified and predicted the nonlinear variation in flow rate with changes in supply voltage, demonstrating a strong correlation with the experimental field data (R² = 0.981). These findings demonstrate the sensitivity of domestic induction-motor water pumps to the voltage fluctuations and highlight the operational risks associated with sustained undervoltage conditions. The developed empirical model provides a practical basis for characterizing pump performance under voltage instability and assessing the effects of voltage fluctuations on domestic water-pumping systems.