Regardless of your plant’s age, your control system is now one of its most critical components. You cannot operate effectively in the 21st century without a modern control system designed for the way your plant works now—and for the way it will work in the future. Upgrading your control system is much more than a “rip and replace” exercise.
Let’s say you’re the lead configuration engineer on the automation portion of a green-field plant installation project, and you need to give your start-up guys a head start with a set of default PID tuning constants. You want to hand it over in a way that the board operators can place some of their basic controls in auto mode with the expectation that the loops will control fairly close to their setpoints without significant oscillation. The following table offers some time-tested default values for gain, integral time, and derivative time that will work in most common situations as a starting point during initial unit start-up. If your control system uses other tuning constant units (e.g., reset for the integral action, then you’ll have to do the conversion – I’m sure you can handle it).