Q1: __________ controller has the maximum stabilising time.

ANS:C - PI

Among the types of controllers typically used in control systems, the controller with the maximum stabilizing time is the P (Proportional) controller. Here's why:

• Proportional (P) controller: This type of controller adjusts the control signal proportionally to the error signal. It does not introduce additional phase lag beyond what is inherent in the process itself. Therefore, while it can stabilize a system, it generally takes longer compared to other controllers to reach a steady state or to stabilize fully, especially in systems with complex dynamics or disturbances.
• PD (Proportional-Derivative) controller: This controller adds derivative action to the proportional action, which helps in damping oscillations and improving response time. It can generally stabilize a system faster than a P controller alone.
• PI (Proportional-Integral) controller: This controller includes integral action, which helps in eliminating steady-state error. It can also stabilize a system faster than a P controller alone, especially in systems with steady-state error.
• PID (Proportional-Integral-Derivative) controller: This controller combines proportional, integral, and derivative actions. It is capable of providing fast stabilization and optimal performance across a wide range of systems, making it versatile and effective in many applications.

Therefore, among the options given, the P (Proportional) controller has the maximum stabilizing time due to its limitation in not compensating for integral or derivative actions, which are crucial for faster stabilization and reducing steady-state error in more complex systems.