Question:
If error remains small but constant, which term grows over time?
Options:
A) Proportional
B) Integral
C) Derivative
D) Gain
View Answer
Correct Answer: B) Integral
Detailed Explanation
When error is small but constant:
- Proportional output remains constant (since it depends only on present error).
- Derivative output becomes zero (because error is not changing).
- Integral output continues to increase over time.
Integral action is defined as:
Since the error persists, the integral term keeps accumulating, gradually increasing controller output until the error is eliminated.
Practical Importance
This is how integral action:
- Removes steady-state offset
- Corrects persistent small deviations
- Improves long-term accuracy
Why Other Options Are Incorrect
A) Proportional → Remains constant for constant error.
C) Derivative → Zero when error is constant.
D) Gain → Gain is a tuning parameter, not a dynamic term.