What happens if the proportional gain is increased too much in a feedback controller?

• A. The system becomes slower and more damped.
• B. The system may exhibit excessive overshoot and possible instability.
• C. The steady-state error is eliminated completely.
• D. The controller output saturates at zero.

Answer: (B)

When you use proportional control, the controller output is proportional to the error: larger gain means a bigger corrective action for the same error. This makes the system respond faster, but it also reduces the damping of the closed-loop system. As you push the gain higher, the poles of the system move in a way that can cause the response to overshoot more and even begin to oscillate. If the gain is increased too far, those oscillations can become unstable, leading to sustained or growing instability. That’s why the best description is that excessive proportional gain leads to excessive overshoot and possible instability.

Increasing gain does not typically slow the response or dampen it; it generally makes it faster and more oscillatory, which is why the other statements aren’t correct. Proportional control alone doesn’t guarantee zero steady-state error for most plants, and saturation at zero isn’t a general outcome from simply increasing gain.