The water supply project often becomes in the high-rise construction or the Industrial and mining establishment and the Small business one of most important infrastructures. At any time can provide the enough water volume, the steady hydraulic pressure, the qualified water quality is to the essential requirements which proposed to the aqueous system. In the present case, the most industries, the living water system uses the water tank, the level to go against the water tank and so on to take the basic water equipment, by first-level or second-level water pump from underground municipal administration water pipe supplies. The topic which therefore, how to establish a reliable security, to be also easy the water supply system which maintains is worth us studying. This article will study and the introduction and so on examines its water level condition using the PLC/PID/monolithic integrated circuit, unifies the programmable control technology, the frequency conversion control technology, the electrical machinery pump group control technology new integration of machinery watering device, through PLC/PID solution control system's stability and accuracy. Thus obtains the good control effect.
key word: PLC Frequency conversion control/constant pressure water supply constant pressure test
