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FIGURE 12.1 Two variable process-control loops that interact.

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Presentation on theme: "FIGURE 12.1 Two variable process-control loops that interact."— Presentation transcript:

1 FIGURE 12.1 Two variable process-control loops that interact.
Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

2 FIGURE 12.2 A compound system for which the ratio of two flow rates is controlled.
Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

3 FIGURE 12.3 Circuit for Example 12.1.
Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

4 FIGURE 12.4 General features of a cascade process-control system.
Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

5 FIGURE 12.5 Cascade control often provides better control than direct methods.
Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

6 FIGURE 12.6 Flowchart for an interactive control problem.
Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

7 FIGURE Loop disturbances can occur from intentional setpoint changes or changes in process load. Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

8 FIGURE Instability in a process-control loop refers to the uncontrolled growth of the controlled variable. Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

9 FIGURE 12.9 Tuning determines the reaction of a controlled variable to changes.
Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

10 FIGURE In one type of cyclic response, the system is adjusted to make each peak down to one-quarter of the previous peak. Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

11 FIGURE 12.11 The minimum-area tuning response characteristics.
Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

12 FIGURE 12.12 Error versus time for Example 12.4.
Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

13 FIGURE 12.13 A transfer function changes the amplitude and phase of a sinusoidal input.
Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

14 FIGURE This control loop has been opened so that the effect of a disturbance on the loop can be traced. Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

15 FIGURE This figure suggests how an initial transient oscillation can grow under the appropriate feedback conditions. Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

16 FIGURE 12.16 A Bode plot shows the open-loop gain and phase versus frequency of an applied sinusoid.
Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

17 FIGURE 12.17 Process-reaction graph for loop tuning.
Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

18 FIGURE 12.18 Process-reaction graph for Example 12.7.
Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

19 FIGURE 12.19 Bode plot for Example 12.9.
Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

20 FIGURE 12.20 Bode plots showing proportional, integral, and derivative mode contributions.
Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

21 FIGURE 12. 21 Bode plots for Example 12. 11
FIGURE Bode plots for Example The proportional mode does not affect phase. Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

22 FIGURE 12.22 Circuit for Problem 12.6.
Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

23 FIGURE 12.23 Process-reaction graph for Problem 12.8.
Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

24 FIGURE 12.24 Bode plot for Problems 12.10 and 12.11.
Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

25 FIGURE 12.25 Bode plot for Problem 12.13.
Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

26 FIGURE 12.26 Bode plot for Problem 12.15.
Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

27 FIGURE 12.27 Process-reaction graph for Problem 12.16.
Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

28 FIGURE 12.28 Bode plot for Problem 12.17.
Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

29 FIGURE 12.29 Process-reaction graph for Problem S12.1.
Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.


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