Abstract : Based on the principle of frequency conversion and speed adjustment and the actual effect of energy saving, this paper analyzes the harmonic effects of the frequency converter itself, pump performance, and speed adjustment occasions. It mainly discusses several easily overlooked issues in frequency conversion water supply from an energy-saving perspective. Keywords : Frequency conversion; Harmonic loss; Pump efficiency; Energy saving Due to inaccurate actual hydraulic measurement data, low efficiency of old-style pumps, outdated adjustment methods, improper selection, and excessive pipeline resistance, the water supply system is inefficient, which contains significant energy- saving potential. In water supply systems, water pumps consume 70% of the electricity, making pump energy conservation crucial. Traditional pump energy-saving methods include pressure regulation and speed control, pole changing scheduling, series pole speed control, hydraulic coupling speed control, and slip differential speed control. Currently, variable frequency speed control (VFD) is more advanced due to its advantages such as stepless motor speed regulation, a wide speed range, and high automation, leading to its increasingly widespread application in the water supply field. However, due to its inherent limitations and considerations of the overall performance of the water supply system, some easily overlooked issues exist in practical use. [b]1 Energy-Saving Principles of Variable Frequency Water Supply Systems[/b] [b][align=center]For more details, please click: Discussion on Several Issues in Energy Saving of Variable Frequency Water Supply[/align][/b]