外文文献、译文.doc

外文文献 Automatic Frequency tower without constant pressure water system 1 .Introduction With industrial control levels. Inverter constant pressure water supply device technology has been relatively mature. In the market to be good reflect. from the economical operation of the system is stable and reliable has been recognized by society. Along with the system controller and inverter technology development is continuously updated and developed. Controllers on the run. From the relay logic, microprocessor, PLC, dedicated controller steps. From Frequency Control, its development has undergone a number of speed control, Simulation given exclusive control of the controller. Every step of development mean that newer and better devices replace traditional methods. The system uses more advanced programmable logic control PLC as a controller to complete the frequency constant pressure water system based on the use of water in different Remote control through online pressure transmitter signal input to the PLC, PID automatic adjustment, pump control operations, to maintain pressure on the water supply pipe network. The system uses a more extensive and can be used for living, Fire and water supply industries in many respects. Below constant pressure to district water supply system as an example. Converter Technology in industrial control system applications. 2. Introduction Process Most of the water supply system prior to using the traditional towers, water tanks, or high-pressure-boosting equipment, But they must pump water higher than the actual height of the pressure referred to upgrade of water, The result of the increase in the pump shaft power and energy loss disc, and the user is not a constant pressure. pressure over the need for regular inflation. equipment increased the danger. Frequency is used without constant pressure water tower technology, can make up for these shortcomings. Frequency - control system through measurement of the pressure on the pipe network, by th