Practical Process Control: Tuning and Troubleshooting (Repost)

Practical Process Control (loop tuning and troubleshooting). Thisbook differs from others on the market in several respects. First,the presentation is totally in the time domain (the word "LaPlace"is nowhere to be found). The focus of the book is actuallytroubleshooting, not tuning. If a controller is "tunable", thetuning procedure will be straightforward and uneventful. But if aloop is "untunable", difficulties will be experienced, usuallyearly in the tuning effort. The nature of any difficulty providesvaluable clues to what is rendering the loop "untunable". Forexample, if reducing the controller gain leads to increasedoscillations, one should look for possible interaction with one ormore other loops. Tuning difficulties are always symptoms of otherproblems; effective troubleshooting involves recognizing the clues,identifying the root cause of the problem, and makingcorrections.
Furthermore, most loops are rendered "untunable" due to some aspectof the steady-state behavior of the process. Consequently, the bookfocuses more on the relationship of process control to steady-stateprocess characteristics than to dynamic process characteristics.One prerequisite to effective troubleshooting is to "demystify"some of the characteristics of the PID control equations. Oneunique aspect of this book is that it explains in the time domainall aspects of the PID control equation (including as thedifference between the parallel and series forms of the PID, thereset feedback form of the PID equation, reset windup protection,etc.) The book stresses an appropriate P&I (process andinstrumentation) diagram as critical to successful tuning. If theP&I is not right, tuning difficulties are inevitable.Developing and analyzing P&I diagrams is a critical aspect oftroubleshooting.