Tag Archive: deadtime

Dec
22

How to Succeed – Part 7

Given a good measurement and final control element selection, location, and installation, we move on to designing the control scheme and achieving the best loop performance. The control system should minimize process interactions and optimize process quality, efficiency, and production rate. The control loops should minimize disturbances and effectively achieve new operating points. Here is …

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Aug
29

Commissioning Control Systems – Process Delay

Single-loop and multi-loop control may be used to address a wide variety of control requirements. However, if a process is characterized by extremely long process delays or by a high degree of process interaction, then other control techniques may be required. The control of quality parameters such as composition is often complicated by large process …

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Jun
06

Addressing Difficult Dynamics, Process Interaction

Single-loop and multi-loop control may be used to address a wide variety of control requirements. However, if a process is characterized by extremely long process delays or by a high degree of process interaction, then other control techniques may be required. In Chapter 16 of Control Loop Foundation – Batch and Continuous Processes, pulp bleaching …

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May
05

Effect of Noise, Update Rate, Trigger Level, and Stick-Slip on Performance

Since the ultimate limit to loop performance depends upon deadtime, the effect of deadband, noise, update rate, trigger level (threshold sensitivity), and valve sensitivity-resolution (stick-slip) on the best possible performance can be estimated by the amount of equivalent deadtime these terms add to the loop. The dependence of loop performance on deadtime for unmeasured step …

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Jan
24

Feedforward Control

One of the fundamental limitations of single-loop control is the fact that all control action is based on the error between the setpoint and the controlled parameter. If there is no error, then the control output will remain at its last value. To correct for process disturbance input using single-loop control, the disturbance input must …

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Jan
03

Process Characterization – Integrating Process

In some cases, a step change in a process input will result in the process output changing continuously. A process that exhibits such a response is known as an integrating process. As part of the chapter on process characterization in Chapter 9 of Control Loop Foundation, we address integrating process response. In the process industry, …

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Dec
20

Process Characterization – Self-regulating Process

Process characterization is the identification of the dynamic responses of a process to changes in its inputs. In Chapter 9 of Control Loop Foundation, we address process characterization. In some cases the process response may be characterized as a pure gain, lag, or deatime. However, many of the basic thermal and physical mechanisms reflected in …

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