Question:
In a PID controller, what happens to derivative output when error is constant?
Options:
A) Increases
B) Negative
C) Maximum
D) Zero
View Answer
Correct Answer: D) Zero
Detailed Explanation
Derivative action depends on the rate of change of error:
If the error is constant:
Therefore:
The derivative term only responds when the error is changing.
Practical Insight
- Constant error → No derivative contribution
- Rapidly changing error → Strong derivative action
This is why derivative does not affect steady-state behavior.
Why Other Options Are Incorrect
A) Increases → Only if error is changing.
B) Negative → Sign depends on error trend, not constant value.
C) Maximum → Occurs only with rapid error change, not constant error.