Tuning (Labvolt)

REPORT Labvolt Configuration

Date Completed: January 20, 2015 ELR212 – Process Control

Clara Dourado & Rafael Carvalho Students

Frank Musso Professor

2

Labvolt Configuration

Hook the Labvolt as shown

LabvoltController

Interface Unit

Voltmeter

4 to 20 ma Calibrator

Input 1

Output 1

12 ma

3 volts

+_

+_

250ohms

Log on to the computer. Select the labvolt program (Labprosim) Select Continue In main menu click on processor Select (Work with process control trainer) Select Continue

3 Configure the Labvolt trainer From main menu select “Setup” Select (Configure analog inputs) Configure analog input one Description …(PV) Maximum …(100) Minimum …. (0) Units .. (%) Filt time constant … (.75) Select .. 1 to 5 volts Make sure (extract square root) is not selected Go to file – select accept setup and return to trainer) Select (YES) Note: Do not use the X to exit the window. This may cause you to loose some of your settings. From main menu go to “Setup” Select (Interface 9065-10) From main menu go to “Setup” Select (Comm Port 1) From main menu go to “Setup” Select (Enable Communication) Light on interface box should start flickering From main menu go to “Setup” Select Sampling rate and set it to 1500 From main menu go to “Trend” Select Set Point – Analog Input 1 and Analog output 1 to trend Record the colours of the trends On controller face plate, find the man/auto switch In manual mode only the operator is allowed to change the output of the controller To change the output click on the numerical value to the right of the controller output meter. In the dialog box, enter the value of the output, and then hit “OK”. The output will go to that value.

4 To enter the tuning parameters and set point value, go to main menu and select “Controller” Selecting the tuning constants will bring up the tuning window for the PID Select set point and in the set point window click “Set Point Tracking” this means that in manual mode only the set point will be the same value as the PV (the value from your 4 to 20 ma calibrator). What are the tuning parameters for the lab volt trainer? Proportional – PB [ X ] or gain [ ] Integral min/repeats [ X ] or repeats/ min [ ] To turn off the Integral, type 100 for the reset value To turn off the Derivative type in 0

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TUNING THE (LABVOLT)

CONTROLLER

Open Loop Tuning Part A PURPOSE: To illustrate the effects of PID on an open loop controller The PV will remain at 50 % the PV is the input from the 4 to 20 ma calibrator

NOTE: LEAVE CONTROLLER IN MANUAL Step 1: Adjust the output (V) for 50%, the set (SP) point 50%, and the input (PV) for 50% Note:

The labvolt controller set point will automatically follow the process when in manual.

PV = Process Variable SP = Set Point V = Output to the valve

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Set Point from 50% to 40%

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Proportional Only Controller Note: WITH CONTROLLER IN MANUAL PROCEED WITH THE FOLLOWING STEPS Step 1 Set up the controller as shown in the diagram above Step: 2 Detune the controller by setting the GAIN (P) to 1 or ( P.B. to 100% ) Step: 3 Record the values observed in the space below. (they should all be at 50%) PV ____48.5__% SP ____50____% V ______50_____% Place the controller into AUTO and adjust the SP from 50 % to 60%

Note the value of the output and record the values observed in the space below.

PV __48.5_____% SP 60% V ____61_____% Graph the result in the graph provided. Place PV, SP and output at 50% Step: 4 Bring the SP down to 40%.

Note the value of the PV and V and record the values observed in the space below.

PV ____48.5____% SP 40% V ___41____% Graph the result in the graph provided . Step 5

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Change the mode back to manual. Place PV, SP and output at 50% Set the GAIN (P) to 2.0 (P.B. 50%) Set the output (V) while still in manual mode to 50 %. Now switch to Auto Mode.

Record the values observed in the space below. (They should all be at 50%) PV ___48.5____% SP __48.5__% V ____50_____% Place the controller into AUTO and adjust the SP to 60%.


PV __48.5____% SP 60% V ____73_____% Graph the result in the graph provided. Place PV, SP and output at 50% Step: 6 Now bring the SP down to 40%.


PV ___48.5____% SP 40% V ____33.5____% Graph the result in the graph provided

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Step 7 Change the mode back to manual. Place PV, SP and output at 50% Set the GAIN (P) to .5 (P.B. 200%) Set the output (V) while still in manual mode to 50 %.

Now switch to Auto Mode Record the values observed in the space below. (They should all be at 50%)

PV ___48.5___% SP ___48.5___% V _____50_____% Step 8 Place the controller into AUTO and adjust the SP to 60%.


PV ___48.5___% SP 60% V ____55.6____%

Graph the result in the graph provided. Place PV, SP and output at 50% Step: 9 Bring the SP down to 40%


PV ___48.5____% SP 40% V ___45.5____% Graph the result in the graph provided

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Proportional + Integral Controller Step 10 Change the mode back to manual. Place PV, SP and output at 50% Set the GAIN (P) to 1.0 (P.B. 100%) Now Add INTEGRAL (reset) of 1 one minute per repeat Set the output (V while still in manual mode to 50 %). Have a watch or timer ready and switch to Auto Mode. Record the values observed in the space below. (They should all be at 50%) PV ___48.5____% SP ___48.5____% V ____51.5____% Place the controller into AUTO and adjust the SP to 60%.

Note: the value of the output and record the values observed in the space below.

PV ____48.5____% SP 60% V ____73_____% Wait for 1 minute after step 10 is completed. What did you observe (notice) with the output (V)?

The output variable changed 13% around of a minute. Step 11 Change the mode back to manual. Place PV, SP and output at 50%

Without changing any tuning parameters adjust the setpoint to 50% Set the output (V while still in manual mode to 50 %). Have a watch or timer ready and switch to Auto Mode. Record the values observed in the space below. (They should all be at 50%)

10 PV ___48.5____% SP ___48.5____% V ___50___% Place the controller into AUTO and adjust the SP to 40%.


PV ___48.5___% SP 40% V ___32___% Wait for 1 minute after step 11 is completed. What did you observe (notice)

with the output (V)? The same thing happened as the previous step, but the voltage decreased 10% in a minute.

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Step 12 Change the mode back to manual. Place PV, SP and output at 50% Set the GAIN (P) to 1.0 (P.B.100%) Add INTEGRAL (reset) of 0.5, Set the output (V) while still in manual mode to 50 %. Have a watch or timer ready and switch to Auto Mode.

Record the values observed in the space below. (They should all be at 50%) PV ___48.5____% SP ___48.5___% V ___50___% Place the controller into AUTO and adjust the SP to 60%.


11 PV ___48.5____% SP 60% V ___83____% Wait for 1 minute after step 12 is completed. What did you observe (notice) with the

output (V)? It is going to be faster because was changed the integral gain, from 1 to 0.5

minutes per repeat. Each 60 seconds the output will change 23%.

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Step 13 Change the mode back to manual. Place PV, SP and output at 50%

Without changing any tuning parameters adjust the setpoint to 50% Set the output (V while still in manual mode to 50 %). Have a watch or timer ready and switch to Auto Mode. Record the values observed in the space below. (They should all be at 50%) PV ___48.5____% SP ___48.5____% V _____50_____% Place the controller into AUTO and adjust the SP to 40%.


PV ____48.5_____% SP 40% V ____24____% Wait for 1 minute after step 13 is completed. What did you observe (notice) with the

output (V)?

12 In a minute the output value should decreases 20% theoretically, but it our case it decreases 16% in a minute.

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Proportional + Integral +Derivative Control Step 14 Change the mode back to manual. Place PV, SP and output at 50% Set the GAIN (P) to 1.0 (P.B. 100%) INTEGRAL (reset) of 0.1, Add DERIVATIVE of 1 R/M, Set the output (V) while still in manual mode to 50 %. Now switch to Auto Mode. Record the values observed in the space below. (They should all be at 50%) PV ____58.5_____% SP ___60____% V ____100____%

Change the SP to 60%. What did you observe (notice) with the display settings?

The output shot up to 100%, and come down. Then the Integral took over and the output starts to slowly rise.

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Step 15 Change the mode back to manual. Place PV, SP and output at 50% Set the GAIN (P to 1.0 (P.B. 100%), INTEGRAL (reset) of 0.01 Add DERIVATIVE of 2 R/M, Set the output (V) while still in manual mode to 50 %. Now switch to Auto Mode.

Change the SP to 60%. What did you observe (notice) with the display settings?

The output came to 100% almost instantly.

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Gain =1 PB =100% I=.1m/r D=1r/m Gain =1 PB =100% I=.01m/r D=2r/m

15

TUNING A

CONTROLLER

Closed Loop Tuning Part B PURPOSE:

To illustrate how feedback affects the tuning of a controller.

Connect the Labvolt as shown below

LabvoltController

Interface Unit

Input 1

Output 1

250ohms

From main menu select “Setup” Select (Configure analog inputs)

16 Configure analog input one Description – PV Maximum - 100 Minimum - 0 Units - % Filt time constant - .75 Make sure (1 to 5 is not selected) We will be working with the internal 0 to 5 volts for this part Make sure (extract square root) is not selected Go to file – select accept setup and return to trainer) Select (YES) Step 1: Place the controller on manual. The set point should follow the process

(PV). The PV will be the same as the output (V) because the output is fed back to the PV input.

Step 2: WITH CONTROLLER IN MANUAL PROCEED WITH THE FOLLOWING STEPS Step: 3 Detune the controller by setting the GAIN (P) to 1 (P.B. to 100%) Integral (I) to 100 M/R (minutes per repeat) D to 0.0 R/M (repeats per minutes) Step: 4 Adjust the manual output (V) to read 50 % Make sure SP is at 50%

Record the values observed in the space below. (They should all be at 50%) PV ____49.6_____% SP ___50____% V ____50.4_____% Step: 5 Place the controller into AUTO and adjust the SP to 60%.


PV ___54.5_____% SP 60% V ____55.5_____%

17 Place PV, SP and output at 50% Step: 6 Bring the SP down to 40%.


PV ____44.6____% SP 40% V ___45.3___%

At this point compare the values for those found in the first part of the lab. Steps 5 &6 part B with steps 3 & 4.in part A

Part A step 3 After SP was changed PV__48.5__ SP __60___ V ___61___ Part B step 5 PV__54.5__ SP __60___ V __55.5___ Part A step 4 PV__48.5__ SP __40___ V __41___ Part B step 6 PV__44.6__ SP __40___ V __45.3__

Why is there a difference in the readings? The difference between the readings values is consequence of the feedback on the controller. The output value (V) will follow Process Variable (PV) in the closed loop. Step 7: Change the mode back to manual and set the GAIN (P) to 2.0 (P.B. 50%),

Output (V) while still in manual mode to 50 %. Make sure SP is at 50%

Now switch to Auto Mode. Step 8: Record the values observed in the space below. (should all be at 50%) PV __49.7___% SP __50____% V ____50.6_____% Place the controller into AUTO and adjust the SP to 60%.


PV ___56.3____% SP 60% V ___57.3____% Step 9: Change the mode to manual and change Output (V) to 50 %. Make sure SP is at 50%

Now switch to Auto Mode.

18 Step 10: Record the values observed in the space below. (They should all be at 50%) PV ___49.7____% SP __50___% V ___50.6____% With the controller in AUTO adjust the SP to 40%.


PV ___43.1____% SP 40% V __43.8____% Step 11: Change the mode back to manual and set the GAIN (P) to 0.5 (P.B.200%) Make sure SP is at 50%

Place output (V) while still in manual mode to 50 %. Step 12: Record the values observed in the space below. (They should all be at 50%) PV ___49.3___% SP ___49.3____% V ____50_____% Place the controller into AUTO and adjust the SP to 60%.


PV ___52.8____% SP 60% V ___53.6____% Switch to manual mode Make sure SP is at 50% Adjust output (V) while still in manual mode to 50 %. Record the values observed in the space below. (They should all be at 50%) PV ___49.3____% SP ___49.3____% V _____50_____%

Place the controller into AUTO and adjust the SP to 40%. Note the value of the output and record the values observed in the space below.

19 PV ___46.2___% SP 40% V ___49.6____% Step 13: Change the mode back to manual and set the GAIN (P) to 1.0 (P.B.100%) INTEGRAL (reset) of 0.1 Make sure SP is at 50%

Output (V) while still in manual mode to 50 % Now switch to Auto Mode. Step 12: Record the values observed in the space below. (They should all be at 50%) PV ___49.8____% SP ___50___% V ____50.8_____% Place the controller into AUTO and adjust the SP to 60%.

Not the value of the output and record the values observed in the space below.

PV ___60____% V __60.9___% Step 13 Wait for 1 minute after step 12 is completed. What did you observe

(notice) with the display settings? The PV will be near to output value. They will change proximity 10% in a minute. Step 15: Change the mode back to manual and set the GAIN (P) to 1.0 (P.B. 100%)

Add INTEGRAL (reset) of 0.01, also set the SP to 50% and output (V) while still in manual mode to 50 %. Now switch to Auto Mode.

Step 16: Record the values observed in the space below. (They should all be at 50%) PV ___50____% SP ___50____% V _____50.7______% Place the controller into AUTO and adjust the SP to 60%.


PV ___60_____% V ___61____%

20 Step 17: Wait for 1 minute after step 16 is completed. What did you observe

(notice) with the display settings? With the Integral gain in 0.01 the process variable will reach 60% faster than step 12. However, will appear an overshoot at the Process Variable curve. Step 18: Change the mode back to manual and set the GAIN (P) to 1.0

(P.B. 100%), INTEGRAL (reset) of 0.1, now add DERIVATIVE of 1 R/M, also set the SP and output (V) while still in manual mode to 50 %. Now switch to Auto Mode.

Step 19: Change the SP to 60%. What did you observe (notice) with the display

settings? The controlled variable does not change to the setpoint. Then the controller output

change all the moment, very fast, to values in a range from 0 to 100% trying to control the process. Step 20: Change the mode back to manual and set the GAIN (P) to 1.0 (P.B. 100%)

INTEGRAL (reset) of 0.01, now add DERIVATIVE of 2 R/M Make sure SP and Output (V) while still in manual mode are at 50 %. Now switch to Auto Mode. Step 21: Change the SP to 60%. What did you observe (notice) with the display

settings? It is still hunting the setpoint and repeat the last process, but faster. Step 22: Now tune the CONTROLLER so that the PV will return to the SP in the

best possible time without cycling (hunting). Time:__8___ sec. Gain __0.5__ I__0.01__ D__0.005__ Step 23: To test your tuning, change the SP from 50 to 80% and record the observed

display values at the beginning of the SP change on the PV, V and the time it takes for the PV to reach SP.

Demonstrate the results to the instructor. Beginning SP 50% PV__50___% V__50.7___% Change set point to 80% End Time __9__sec. PV__80__% V__81.3__%

21 Questions

1) What does PID stand for? Proportional, Integral and Derivative.

2) What is the difference between gain and proportional band? Gain: The ratio of the change in output signal to the change in input signal defines controller gain. Proportional Band: The amount of change in the controlled variable, expressed in engineering units, required to move the actuator from one end of its stroke to the other. This is also referred to as throttling range.

3) If the PV does not move when a SP change is made and a controller has both PI, where will the output wind up? It is made a change up at the setpoint value, the output value will increase proportionality and continuously until reach 100%. It is made a change down at the setpoint value, the output value will decrease proportionality and continuously until reach 0%.

4) A closed loop system is tuned with a PB of 100% and an Integral of 2 repeats/min. The set point and process are both at 50%. If instantly the PV deviated from SP by (-15%) where would the output V be after 1 minute if it was sitting at 30%? (-15% means the PV is falling below the set point) The output will go to 60.

5) A closed loop system is tuned with a Gain of 2 and an Integral of 2 min/repeats.

The set point and process are both at 50%. If instantly the PV deviated from SP by (-10%) where would the output be after 1 minute if it was sitting at 20%? The output will go to 60.

6) Graph questions 4 and 5.

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PVSP

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Documents

Tuning (Labvolt)