Question:
Which PID term depends only on the present value of error?
Options:
A) Proportional
B) Integral
C) Derivative
D) Bias
View Answer
Correct Answer: A) Proportional
Detailed Explanation
The Proportional (P) term depends solely on the current (instantaneous) error.
Mathematically:
Pout​ = Kp ​ ×e(t)
Where:
- ( Kp ) = proportional gain
- ( e(t) ) = present error (SP − PV)
This means:
- If error increases → output increases proportionally
- If error decreases → output decreases
- If error = 0 → proportional output = 0
It does not consider past error (Integral) or future trend (Derivative).
Why Other Options Are Incorrect
B) Integral
Depends on accumulated past error over time.
C) Derivative
Depends on the rate of change of error (future prediction behavior).
D) Bias
Bias is a fixed baseline output, not dependent on error.
Quick Memory Trick
- P → Present
- I → Past
- D → Future