Question:
What is manual mode in a PID controller?
Options:
A) PID auto adjusts
B) Tracks setpoint
C) SP follows PV
D) Operator sets output
View Answer
Correct Answer: D) Operator sets output
Detailed Explanation
In manual mode, the PID algorithm is bypassed and the operator directly sets the controller output (CO).
This means:
- The controller does not calculate error (SP − PV).
- Proportional, Integral, and Derivative actions are inactive.
- Output remains at the value manually entered.
Manual mode is commonly used during:
- Startup
- Maintenance
- Troubleshooting
- Commissioning
Why Other Options Are Incorrect
A) PID auto adjusts
This describes automatic (auto) mode.
B) Tracks setpoint
This relates to setpoint tracking or servo response, not manual mode.
C) SP follows PV
This is setpoint tracking behavior used to prevent bumps during auto/manual transfer.
Practical Insight
In manual mode:
Controller → No automatic correction
Operator → Full control of output