# Nt2580 Unit 6 Study Guide

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Assignments 6 thru 10 excluding # 9 6. Describe ratio control. How does it differ from Cascade control? Include a self drawn and labeled trend graph that demonstrates a set point change and a load change. Explain the differences in the two trends. What would be an application that ratio control would be utilized? 7. How is a cascade control loop different from a single control loop? Include a self drawn and labeled trend graph that demonstrates a primary set point change and load change. What is meant by an inner loop and outer loop? What would be an application that cascade control would be utilized? 8. Describe and explain the function of a feed forward control loop. Include a self drawn and labeled trend graph that demonstrates a set…show more content…
Gain (See Note 1) TI (See Note 2) Period Decay Ratio I Period T As found 1 2 3 4 5 6 7 8 9 10 NOTE 1: If you are working in Proportional Band, enter the value of Proportional Band, rather than Gain. NOTE 2: If you are working in Reset Rate (repeats/min), rather than Reset Time (minutes/repeat), take the reciprocal of the reset rate to obtain Reset Tiime (TI). 3. A COMPARISON Many (novice) loop tuners, faced with the “as found” condition, would simply reduce the controller Gain until acceptable damping (e.g., quarter-wave decay) was achieved. We will demonstrate why that may not be a good idea. 3.1 Re enter the original tuning parameters. With the loop in Automatic, set the set point at 275 DegF and let the loop come to equilibrium. Working between set point values of 275 and 325 DegF, adjust the Gain until quarterwave damping is achieved. Do not change the reset. Gain: ________ Exercise 11 4 IMPROVING “AS FOUND” TUNING Change the set point to 275. When the loop comes to equilibrium, make a 10% disturbance (load change) by clicking twice - rapidly - on StepIncr. Record: Maximum deviation of PV from set point: ________ How long before loop “settles down” to within 1/2% (± 2.5 Deg) of SP…show more content…
DETAILED ANALYSIS 6. ANOTHER CALCULATION CYCLE, FOLLOWING A LOAD CHANGE The following pages give an example of the worksheets which are requested by the exercise. Your data will probably be different, because no two persons will start collecting data for the worksheet with the process in the same state. Nevertheless, the example should be helpful. Note that your predicted profile (for example, column 4) should agree with the computer-generated date (for example, column 5) except for possible round-off error in the second place to the right of the decimal. 7. OTHER EXPLORATION (Optional) 7.2 Multiple-Input, Multiple-Output One at a time, change the set points for PV-1 and PV-2. Do both outputs change? Yes Does the other PV stay approximately on SP? Yes .... You should be seeing a random load change of both disturbance variables. Do both PV’s stay approximately on SP? Yes 7.3 Insufficient Degrees of Freedom With a higher priority given to PV-1, it will control closer to its set point, but at the expense of more deviation at PV-2. Is this what you observe? Yes ... priority for PV-2 of 0.95. Do the PVs move in a way that you would expect. Yes. PV-2 is closer to SP. There is more deviation of