labmanual 2008 final

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Instrumentation, Control & Industrial Practice Laboratory Manual

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to its setpoint value. Determine what the maximum input flowrate is, for which the

controller is not able to stabilize the system anymore. Explain in your report what the

reason is and give an explanation how the maximum input flowrate, for which the

controller can stabilize the system relates to the output flowrate from the tank.

Effect of controller sign an system stability

1. With the best set of controller parameters change the sign of the controller gain Kc.2. Give a setpoint change and observe and RECORD the controller action and systems

behaviour.

PLEASE NOTE

After Part I and II are completed and before leaving the laboratory, shut-down the rig

using the nominal shut-down procedure set out in the appendix.


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APPENDIX A

Nominal Start-up Procedure

1. Turn off all hand valves.2. Turn on the compressed air at the ball valve on the supply line.3. Turn on the computer.4. Turn on the electricity main for the instrumentation.5. Run the control program.6. To avoid surges through the glass rotameter, slowly open the water supply hand valve.7. Set an desired input flow rate. Recommended values:

Rig 1: 0.3 m3/h

Rig 2: 5 l/min

Rig 3: 380 l/hRig 4: 3 l/min

Rig 5: 220 l/h

Rig 6: 6 l/min

8. When enough water is in the tank, turn on the outlet pump at the electricity mains.9. Make sure the controller is in AUTO mode and allow the controller to bring the liquid

level to steady state.

Nominal Shut-down Procedure

1. Turn the controller OFF and open the control valve.2. Turn off the water supply at the hand valve.3. When the tank is empty, turn off the outlet pump at the electricity mains.4. Transfer any stored data to a floppy diskette, memory stick, your network drive, or email

to yourself.

5. Turn off the computer at the electricity mains.6. Turn off the instrumentations power supply at the electricity mains.7. Turn off the compressed air at the ball valve in the supply line.8. Place beakers under the drain cocks and drain the system.9. Close all drain cocks.10.Make sure that all electrical devices are switched off and that water is not dripping from

the mains water supply.


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APPENDIX C

Introduction to the software interface

The software interface allows you to interact with the experimental rig and record all data. Themain parts of the interface are shown below. There are three panes with different functionality:

Process Diagram Controller Configuration

In the first week you need the functionality of the Process Diagram pane only, whereas in the

second week you will work with both the Process Diagram and the Controller panes. The

configuration pane should normally not be used during the laboratory exercise.

Fig. 2. The Process Diagram pane of the laboratory software


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Fig. 3. The Controller pane of the laboratory software

Saving your data

Making sure that your data is saved is your responsibility. The software offers several ways to

record you data.

1. - By pressing the save to file button, your data will be saved in a data file, which canbe opened by any standard text editor or Excel. Your data will be saved from the

moment you pressed the button onward, until you stop the data recording. No data

acquired before the moment you activate data recording will be saved in the file. Whenyou activate data recording the software will prompt you for a file name. You can select a

file name in your home folder (U drive). The data is recorded at every sampling time. The

order of the columns is as follows:

Time (s); Level (%); SP (%); MV (%); FlowRate; Level(V);

2. - By pressing the Send to Excel button, you can send the data from the memory ofthe software to an Excel workbook. This option works in the opposite way as the Save

button. By pressing the button data stored in the memory from the moment you started

the software until the moment the button was pressed will be sent to Excel.


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3. You can also copy paste snapshots of the plot into your report. However to perform thedata analysis you need the values saved with method 1 or 2 above. For the qualitative

analysis part or for the appendix it is acceptable however to use the snapshots. This can

be obtained by right clicking on the figure widow and selecting Export Simplified

Image, then paste it in Word, as shown in the figure below.

Fig. 4. Exporting snapshots of the plot to other applications

labmanual 2008 final

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