The 7th AMATROL T5552 user manual was used in order to experiment on the behavior of the PID controller, the experiment described on the user manual consisted on turning on both the solenoid valve 3 and the pump; this resulted on having water entering and leaving the tank at the same time, a set value was given to the PID controller and different constants were given for the proportional, differential and integral gains according to the ones proposed on the user manual.
A set point of 5 inches was given to the PID controller and the experiments consisted on measuring the water level every five seconds until it stabilized, on the next tables you'll be able to see the value of water level across time for both experiments.
Table 1 - Data obtained from experiment with Kp=30; Kd=1.6; Ki=1.0
Table 2 - Data obtained from experiment with Kp=40; Kd=2.0; Ki=0.2
The following plot shoes both experiments and how they compare with each other.
Comparison of both responses on a scatter plot
Even though two sets of constants were used it's possible to appreciate that both responses are really similar, one of them is slightly faster because of the different constants that were used, nevertheless the establishing time is acceptable when the nature of the process is taken into account.