DISCUSSIONThis project was tittle controllability of level control using various tuning rule . The objective of this project is to compare the value of the level control calculation by using 2 methods which is:1. Tuning Rules by Ziegler Nichols2. Tuning Rules by Cohen Coon In this project our group use equipment FIC 21 to control the flow. From these 2 methods, our group need to calculate the value of dead time ( , time control (), response rate (RR), proportional + integral + derivative (PID) and also. Then, based on the result our group will compare Pb, I and value that has been calculated. The purpose of PID mode is to fast process response and noisy processes like flow, pressure and liquid level control.This project is start with open loop test. First, the manipulated variable (MV) is at 30% at level 2.1mm. Then, we set the controller to manual mode and increase the MV by 5%. Ensure that the level is not exceeding 600 mm when the controller is set to auto back. After that, the value of response rate (RR), dead time (Td), time control () is calculated from the graph we obtained. The value of RR is 0.357 s-1 ,Td is 1.23 s, and is 3.44s.After that, we proceed to next step which is set point test by using the 2 methods of tuning rules. For this set point test, we calculate using 2 difference modes which is PI and PID. These 2 modes consist of different type of calculations as shown in table 1.5. After that we wait until the graph become stable then repeat the same step for load disturbance test. There will be 4 different graphs because of using 4 different calculations.

The first method is using Tuning Rules by Ziegler - Nichols. The value of PB, KC and I for mode PI are 48.785%, 2.05 and 4.096 s whereas for mode PID the value of PB, KC , D and I for mode PI are 36.578%, 2.734, 0.615 and 2.46 s. The 2nd method is using Tuning Rules by Cohen Coon. The value of PB, KC and I for mode PI are 42.527%, 2.351 and 2.366 s whereas for mode PID the value of PB, KC , D and I for mode PI are 30.35%, 3.295, 0.425 and 2.713 s.The difference between 2 method that has been used, it shows that the performance test (load disturbance test) for mode PI are more constantly oscillatory than performance test that were conducted in mode PID which it fluctuate oscillatory. It shows that the MV graph cannot reach its stable set point due to value of KC and I that not exact value for both methods. Besides that, set point test that we conducted, we obtained a good positive off-set in both modes for both methods.In order to stabilize the graph, we need to increase the value PB and I and also decrease the value of KC. When the value of PB increasing, the controller action become slower which in turn slows down the process response and shift the graph to the right. An increasing I value, the controller action will also become slower and lower the peak of the graph. The value of KC should be decrease because decreasing the KC value will increase the PB value. PB value is inversely proportional to KC value.

AppendixTuning Rules by Ziegler NicholsModePID

P100RR Td--

P I111.1RR Td3.33 Td-

P I D83.3RR Td2 Td0.5 Td

Tuning Rules by Cohen Coon ModePID

PRR Td--

P IRR Td3.33 [Td-

P I DRR Td2.5TdTd

Where Td/ Tc