Concept:
The Ziegler-Nichols (Z-N) closed-loop tuning technique is an empirical method based on finding the ultimate gain \(K_u\) and ultimate period \(P_u\) where the system exhibits sustained oscillations under pure proportional control. Fixed mathematical design ratios are then used to calculate P, PI, or PID controller parameters.
Step 1: Recalling the classic Z-N tuning formulas for a PID controller.
For a full Proportional-Integral-Derivative (PID) loop architecture, the standard Ziegler-Nichols rules specify the following tuning criteria:
• Controller Gain: \( K_c = 0.6 \cdot K_u \)
• Integral Time Constant: \( T_I = \frac{P_u}{2} = 0.5 \cdot P_u \)
• Derivative Time Constant: \( T_D = \frac{P_u}{8} = 0.125 \cdot P_u \)
Step 2: Calculating parameter values using the given data.
The problem provides the following operating parameters:
\[ K_u = 2, \quad P_u = 3 \text{ minutes} \]
Let's compute each tuning constant individually:
• Calculate \(K_c\):
\[
K_c = 0.6 \times K_u = 0.6 \times 2 = 1.2
\]
• Calculate \(T_I\):
\[
T_I = \frac{P_u}{2} = \frac{3}{2} = 1.5 \text{ minutes}
\]
• Calculate \(T_D\):
\[
T_D = \frac{P_u}{8} = \frac{3}{8} = 0.375 \text{ minutes}
\]
Reviewing the available choices, the calculated array matches option (B) exactly.