If there is any difference between the two response, the system drives the plant, via the actuating signal, to make a correction. If there is no difference, the system does not drive the plant. Examples –air conditioning, lift, washing machine (water level control) System Configurations : ii) Closed-loop Control System (CLCS)
19BETR 2383 Control System FundamentalControllerProcessOr Plant+-Errorsumming junctioninputTransducerOutputtransducer= sensor summing junctionsumming junction++++Disturbances 1 Disturbances 2 Closed-loop systemController OutputActuator Process Sensor Desired output responseSystem Configurations : ii) Closed-loop Control System (CLCS)
20BETR 2383 Control System Fundamental20OLCSCLCSCLCSOLCSOLCS & CLCSOLCS
21BETR 2383 Control System FundamentalSystem ConfigurationsThe differences between open and closed-loop system are:-Closed-loop SystemOpen-loop SystemHave the feedback pathDoes not have the feedback path Output response: greater accuracyOutput response: not accurate Less sensitive to noise, disturbances and changes in the environmentSensitive to noise, disturbances and changes in the environment The system can compare the output response with the input and make a correction of there is any differenceThe system cannot correct the disturbances. So it does not have any corrective action.More complex and expensive.Simple and inexpensive.
22BETR 2383 Control System FundamentalSystem Configuration DifferencesThe differences between open and closed-loop system are:-Does not have a loop Thus, it does not have any corrective actionOpen-loop systemActual / current condition is taken as a data to calculate the necessary corrective action needed. Corrective action is needed to maintain the desired value. Positive / negative feedbackClosed-loop system