Question:
What does dead time in a process cause in control response?
Options:
A) Higher stability
B) Delayed correction
C) Zero overshoot
D) Reduced noise
View Answer
Correct Answer: B) Delayed correction
Detailed Explanation
Dead time (also called pure time delay) is the time interval between:
- A change in controller output
and - The first visible response in the process variable (PV)
During dead time:
- The controller acts
- But the PV does not respond immediately
- No corrective feedback is available
This results in delayed correction, making the system harder to control.
Impact on Control Performance
Dead time:
- Reduces stability margin
- Increases oscillation tendency
- Makes tuning more difficult
- Requires conservative tuning
Processes with large dead time are more prone to instability.
Why Other Options Are Incorrect
A) Higher stability → Dead time reduces stability.
C) Zero overshoot → Dead time often increases overshoot.
D) Reduced noise → Dead time does not filter noise; it delays response.