EFFECT OF VALVE AND VARIABLE FREQUENCY DRIVE DYNAMICS
The control valve and variable frequency drive (VFD) are the final control elements that directly affect the process by manipulating a flow. The expectation is that these elements do their job and do not adversely affect the tuning and performance of the loop. Most control text books do not include details of the final control elements in the analysis or solution. Until recently, most users were not aware of the potential problems. Here is a perspective, overview, and recommendations.
Prior to the 1980s, nearly all final control elements were control valves supplied by throttling valve manufacturers. Since these valves were originally designed for ...