Methods for calculating the time characteristics of the elements of an automated control system on the example of a closed loop for regulating the pressure in a pipeline section under the control of the “OWEN PLC100 220”

This article deals with the problem of time delays in the transmission of information from the primary drive to the governing body with automatic process control systems. Nowadays there are no methods which check the effect of time delays of the information signal on the loop response time, which leads to an inefficient use of system resources. The longer time interval between the change in process variable and control can also lead to negative consequences. As a tool for the study of the system the parametric identification of each selected component followed by drawing a time sequence diagram is used. During the synthesis of the sequence diagrams of time delays, the structural diagram of the control loop is separated into two components: regulative (displays the elements of the control loop directly involved in the process) and informative (maps elements that do not affect the process of automatic adjustment of the process parameter). Separation of the elements related to regulatory or informative map is based on the effect on the total time under consideration of automatic control loop system response. Taking into account the technical parameters of each node of the regulatory chart and the general technical documentation, a model of the functioning of each ele- ment in the form of a graphic image (sequence diagrams) is compiled. Based on the models obtained, two sequence diagrams are compiled with the maximum and minimum speed of the control loop under consideration, by shifting the model of elements relative to each other. As an example, there is a calculation of a separate air pressure control loop in the pipeline, consisting of: a “METRAN 100 DIO 1051” primary transducer, an object communication device (UCO) “ELEMER EL 4019”, a programmable logic controller “OWEN PLC 100 220”, a UEL “ELEMER EL 4024”, 6.3 / 20-0.63-01, the communication between the controller and the USO is carried out using the RS485 network interface (MODBUS RTU protocol).