Abstract : This paper introduces the design concept and implementation method of an unattended automatic constant pressure water system with multiple functions including domestic and fire protection, constructed using frequency converters, PLCs, supporting electrical appliances, and water purification equipment in a large community. Keywords : Frequency converter, multi-functional constant pressure water supply, programmable controller 1 Introduction With the continuous expansion of urban construction, the pressure of urban public water supply networks can no longer meet the requirements of residential water use. Secondary pressurization measures, including elevated water tanks, pressure tanks, and variable frequency speed control direct water supply, have been widely adopted. In densely populated public areas such as universities and large residential communities, water consumption is high, water usage is relatively concentrated, and there are special requirements such as fire-fighting water. Therefore, the requirements for the automation level of secondary pressurization facilities are increasing, water quality requirements are also constantly improving, and the design of electrical systems has special functional requirements and technical characteristics. The central water supply pumping station of Shijiazhuang Railway Institute is responsible for the secondary pressurization of teaching and domestic water for over 10,000 faculty, students, and their families. The reservoir has a capacity of 800m³. The entire pumping station includes three 55kW pumps for fire-fighting pressurization, three 22kW pumps for domestic water pressurization, and one 7.5kW pump for nighttime pressure replenishment. In addition, the system includes two submersible sewage pumps for wastewater discharge from the reservoir and the pump house, respectively. Regular disinfection is required to ensure water quality in the reservoir. Calculations show that during the three peak water usage periods (morning, noon, and evening), the three domestic water pumps generally need to operate at "one variable frequency and one fixed frequency"; during other daytime periods, the base frequency is constant; and at night, only the small pump operating at variable frequency is sufficient to meet the water pressure requirements. Therefore, the electrical system needs to be designed according to these requirements. [b][align=center]For details, please click: Design of a Multifunctional Constant Pressure Water Supply System with Variable Frequency Speed ​​Regulation in University Area[/align][/b]