东南大学自动化2015过程控制期末试卷.pdfVIP

(过) 1.accroding to statistics, please tell which one is the main reason that cause a control system shutdowm, controllers, sensors or actuators? actuators 2.When we install a control value in practical industries, why we usually instell a bypass line? Draw the diagram. It can make the system more simple, flexible, and it also can protect the system 3.Why pracess engineers always perfer DSC or PLC to miero-chip units, such as a single chip computer? Please give at least 2 reasons. The cost is low, safety performance is good 4.Someone think when valve’s opening is 30%,then the flowrate is 30% of the maximum flowrate, what do you think. Depending on the valve, minimum flow cases, valve opening can not be lower than 15% 5.We always use 4-20mA other than 1-5V for signal interface in process control field? Because the distance between scene and control room is too far, so it will produce a larger error,.if we use this signal system, we can improve the transmission accuracy. PID 1.Please give the discrete PID algorithm, in increment form u(k)=u(k-1)+△u(k). Show △u(k). 2.In which conditions can we consider tu use derivative action? Give at least 2 point. Large overshoot, reaction speed slowly 3.What is most typical transfer function to dercribe an industrial process? What is the intergral time if you tune a PI controller for this kind of process? CSTR 1.The original temperature control system is designed only by mainpulating the jacket in let valve opening. Please point ont its problems when applied in real prectice, at least 2 point. Radiator pipe line, solar heating system 2.If the jacket intlet pressure fluctuates greatly, how to deal with this problem? Draw schematic. Voltage regulator valve at the exit of a flow-limiting valve with a trachea string to use 3.If the Tjm fluctuates from time to time, show you inproved design. Draw control blook. Feed forawrd 1.what’s the necessary condiction for feed f