What does deadtime in a control loop describe?

What does deadtime in a control loop describe?

• A. The delay between input change and observable output change
• B. The time required for the controller to update output
• C. The moment when the loop reaches steady state
• D. The time taken for a signal to propagate through wiring

Answer: (A)

Deadtime is the delay between when you change the input to a process and when the change is actually observed at the output. This delay comes from transport through the system, actuator and sensor response, and other dynamics in the plant, so the output stays momentarily unchanged even though the input has changed. It isn’t the controller’s own processing time, nor the moment the loop settles to a new steady state. While wiring propagation contributes to this delay, deadtime refers to the overall lag from input modification to observable output response. In control design, recognizing deadtime helps you account for phase lag and potential instability, sometimes using methods like a Smith predictor to compensate for large delays.

Deadtime is the delay between when you change the input to a process and when the change is actually observed at the output. This delay comes from transport through the system, actuator and sensor response, and other dynamics in the plant, so the output stays momentarily unchanged even though the input has changed. It isn’t the controller’s own processing time, nor the moment the loop settles to a new steady state. While wiring propagation contributes to this delay, deadtime refers to the overall lag from input modification to observable output response. In control design, recognizing deadtime helps you account for phase lag and potential instability, sometimes using methods like a Smith predictor to compensate for large delays.