Loop Controllers

June 12, 2008
CONTROL’s Monthly Resource Guide

Every month, CONTROL’s editors take a specific product area, collect all the latest, significant tools we can find, and present them here to make your job easier. If you know of any tools and resources we didn’t include, send them to [email protected], and we’ll add them to the website.

Two-day process-control and loop-tuning course familiarizes students with common industrial control loops and gives them the abilities to set up, tune and troubleshoot common control loops. The course covers a variety of control techniques such as on/off control, proportional control, proportional-integral control and full PID control.

Performance monitoring of closed loops—or Control Loop Condition Monitoring (CLCM)—is used to automatically assess controller performance. In this article, ABB’s control conditioning monitoring technology is reviewed. CLCM works like a doctor’s stethoscope: It obtains a diagnosis by passively listening to the process. Automated CLCM is highly attractive in most plants because there are simply too many control loops to be maintained by one service engineer on a regular basis; i.e., at least every six months. CLCM is also inherently non-invasive. This white paper can be found at http://tinyurl.com/5luex2.

In this paper, the authors identify the poor dynamic response of the standard PID algorithms in the case of lost communications. An enhanced algorithm is proposed to improve the dynamic response under these conditions. When there is no communication loss, the enhanced PID block acts exactly the same as a standard PID block. When there is no communication loss, the enhanced PID block acts exactly the same as the standard PID block. Lost data is compensated for by the integral component in the enhanced PID block. When communications are reestablished, the derivative component in the enhanced PID block eliminates the possible spikes in the output. These authors have evaluated the enhanced PID algorithm under several wireless scenarios and describe the advantages of the enhanced PID algorithm.

This company offers loop-tuning and process control strategy training classes. Designed for engineers and technicians, the classes cover basic terminology and building blocks of process control, as well as fundamentals and advanced process control techniques using this company’s fully automated control solutions.

Electronics.ca Publication
This report covers the market for electronic analog, microprocessor-based single-loop and multi-loop temperature controllers. It was designed to serve as a marketing tool for companies that currently manufacture these products or for companies who are considering entering the business. The study provides insights, trends and data on the 2005 global market through 2010. Forecasts are given for units and dollar volumes, and average setting prices for each of the three classes of temperature controllers. The complete report is available for purchase at www.electronics.ca/reports/instruments-sensors/industrial_electronic.html.

Recorded webcast is for professionals responsible for hundreds, even thousands of regulatory control loops and require the ability to monitor, identify, diagnose and remedy all control issues before they impact plant performance. You will learn how to enable tuning through non-disruptive, closed-loop testing; test, tune and trend multiple loops simultaneously; use multivariable models to tune interactive loops; and leverage Taiji process control technology.

University of Michigan
The University of Michigan offers online tutorials for Matlab and Simulink programs. Matlab is an interactive program for numerical computation and data visualization used extensively by control engineers for analysis and design. Simulink is a graphical extension to Matlab for modeling and simulation of systems. The PID tutorial shows the characteristics of the each of proportional (P), the integral (I), and the derivative (D) controls, and how to use them to obtain a desired response. The tutorial also contains general tips on designing PID controllers.