Question:
Which PID mode accumulates error over time?
Options:
A) Proportional
B) Integral
C) Derivative
D) All modes
View Answer
Correct Answer: B) Integral
Detailed Explanation
The Integral (I) mode accumulates error over time by continuously summing the deviation between SP and PV.
Mathematically:
This means:
- If error persists → Integral output keeps increasing
- If error is small but constant → Integral slowly builds correction
- If error becomes zero → Integral stops accumulating
This accumulation allows integral action to eliminate steady-state offset.
Why Other Options Are Incorrect
A) Proportional → Depends only on present error, not accumulated error.
C) Derivative → Depends on rate of change of error, not its history.
D) All modes → Only integral accumulates error over time.