住宅楼低区变频恒压供水系统采用西门子PLC拖动变频器一拖三控制方式。接触器与变频器相配合使用达到系统所需压力。(The variable frequency and constant pressure water supply system in the low area of the residential building uses the SIEMENS PLC to drag the frequency converter and the three control mode. The contactor and the frequency converter are used in combination with the pressure required to achieve the system.)