Question:
Which PID mode has no direct effect when error is constant?
Options:
A) Proportional
B) Derivative
C) Integral
D) All controllers
View Answer
Correct Answer: B) Derivative
Detailed Explanation
Derivative action depends on the rate of change of error:
When the error is constant, its rate of change is zero:
Therefore, the derivative term produces no output contribution.
Why Other Modes Still Act
Proportional → Produces output proportional to the constant error.
Integral → Continues accumulating the constant error over time, increasing output.
Only the derivative term becomes inactive when error does not change.
Why Other Options Are Incorrect
A) Proportional → Still produces output if error exists.
C) Integral → Continues integrating constant error.
D) All controllers → Incorrect; only derivative has zero effect under constant error.