Modern manufacturing and process industries are often largely run by distributed control systems (DCSs), with minimal input from operating personnel. This has largely been made possible by the evolution of computer and controller hardware and software.
The basic building block of a process control systems is the process control loop. Process control loops utilize sensors, transmitters, calculations or algorithms, processing systems, and actuators or outputs. Their ultimate goal is to help a process run in a stable, predictable, consistent manner. Some common examples of process variables that are controlled by control loops include tank levels, liquid flows, air temperatures, and steam pressures.
A large industrial processing facility, like an oil refinery or paper mill, utilizes thousands of process control loops. This type of facility also typically utilizes a data historian to store data related to their control system or systems, plus other significant data. This data contains a wealth of information that can be used as a powerful troubleshooting or optimization tool. The trick is knowing how to use it.