Which statement differentiates deadband from deadtime in a control loop?

Which statement differentiates deadband from deadtime in a control loop?

• A. Deadband is a delay before any output change; deadtime is the range around setpoint where no response.
• B. Deadband is the range around setpoint with no response to small errors; deadtime is the delay between input change and output change.
• C. Deadband is the time delay before the controller computes a response; deadtime is the instantaneous output change.
• D. Deadband and deadtime are the same concept.

Answer: (B)

Deadband and deadtime describe two different ways a control loop can respond (or not respond) to changes. Deadband is the range around the setpoint where small errors don’t cause any output change. This means the controller stays idle if the process value is close enough to the target, which helps prevent output chatter from minor fluctuations. For example, if the setpoint is 100 and there’s a deadband of 2, the controller won’t react to errors between 98 and 102. Deadtime, by contrast, is a time delay between when the input changes and when the output actually responds. This delay comes from sensor response, transport or communication lags, and the dynamics of the actuator and process. So you might change a input, but the effect won’t be seen in the process variable until some seconds later. So the statement correctly separates the concepts: deadband is the range around the setpoint with no response to small errors, while deadtime is the delay between input change and output change. The other descriptions mix up these ideas or say they’re the same, which isn’t accurate.

Deadband and deadtime describe two different ways a control loop can respond (or not respond) to changes. Deadband is the range around the setpoint where small errors don’t cause any output change. This means the controller stays idle if the process value is close enough to the target, which helps prevent output chatter from minor fluctuations. For example, if the setpoint is 100 and there’s a deadband of 2, the controller won’t react to errors between 98 and 102.

Deadtime, by contrast, is a time delay between when the input changes and when the output actually responds. This delay comes from sensor response, transport or communication lags, and the dynamics of the actuator and process. So you might change a input, but the effect won’t be seen in the process variable until some seconds later.

So the statement correctly separates the concepts: deadband is the range around the setpoint with no response to small errors, while deadtime is the delay between input change and output change. The other descriptions mix up these ideas or say they’re the same, which isn’t accurate.