When is a controller in automatic not able to do anything to reduce an oscillation? When will a controller amplify an oscillation? In both of these cases, the controller is doing more harm than good by wearing out valves and upsetting other loops.
Sensor lags, transmitter damping, and PID signal filters can make oscillations look better but is this really a good a thing? Here we look at how these dynamics affect what you see and how much of a problem it can be.
Tuning has a profound effect on the practical limit to control loop performance. While the effect of execution time and filter time is often much less in comparison, these time settings can get the user into trouble depending on tuning and loop dynamics. Here is a perspective, overview, and recommendations.
A transmitter damping setting or signal filter setting that is too slow can not only degrade performance but also cause trips. Less understood is that a large filter setting can mislead operations into thinking the filter has helped rather than hurt the process.