Terminology

Process control systems engineering refers to the practice of engineering involved in the design of control and automation of industrial processes. Like any other engineering discipline, it has its unique set of terminology:

Process Control is having the control system maintain each individual controlled variable (flow, pressure, temperature, level, etc.) at its desired operating point (setpoint). Some control systems do this better than others due to factors such as design, implementation and control loop tuning.

Process Instrumentation includes the sensors, transmitters, control valves, and various related items used to monitor and control a process. All instruments involved in the measurement and control of one process variable are collectively referred to as a control "loop".

Control Loop Tuning is the practice of adjusting the dynamics of each loop controller to achieve a rapid and stable response to a process upset or setpoint change. The majority of control loops are not tuned for optimal performance due to improper/no initial tuning or to operating the loop at a significantly different setpoint. This is an impediment to successful implementation of process automation but, at the same time, presents a large opportunity for process improvements to be realized with relatively little expenditures.

Process Automation is having the control system do more with less human intervention, including automatically changing the setpoints of all controlled variables in concert to achieve a common objective (e.g. increase/decrease production, react to a process upset, make product changes) or performing each step of a batch process. This requires changing the focus from individual loops to the complete process but successful implementation still requires that the individual control loops are performing properly.          

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