The water supply control system is generally installed in the water supply control cabinet, including three parts: PLC controller, frequency converter and electric control equipment. The PLC controller is the core of the entire variable frequency constant pressure water supply control system. It directly collects information such as the operation of the inverter and the overvoltage of the power grid; analyzes the data from the inverter, implements control algorithms, and obtains a control plan for the actuator , Through the frequency conversion governor and contactor to control the actuator (ie water pump unit); the frequency converter is a unit for speed control of the water pump, which tracks the analog signal sent by the water pressure transmitter to change the operating frequency of the speed control pump , Complete the speed control of the speed control pump.