Static error versus dynamic error: which statement correctly describes static error?

Static error versus dynamic error: which statement correctly describes static error?

• A. Dynamic error occurs during change due to lag, dead time, or response.
• B. Static error changes with temperature.
• C. Static error is a steady offset under steady state.
• D. Dynamic error is a random variation in measurement.

Answer: (C)

Static error is the persistent difference you see when the process variable has reached a constant input and settled at a steady state. It represents a fixed offset between the true value and the measured value under those steady conditions. That is why describing static error as a steady offset under steady state is the best way to define it. Dynamic error, on the other hand, concerns how the measurement responds to changes. It includes lag, dead time, and the finite response time as the input changes, so the reading may temporarily deviate while the system catches up. Saying static error changes with temperature shifts the focus to drift, which is not the defining feature of static error. Saying dynamic error is a random variation describes noise, which is not the core notion of dynamic error either.

Static error is the persistent difference you see when the process variable has reached a constant input and settled at a steady state. It represents a fixed offset between the true value and the measured value under those steady conditions. That is why describing static error as a steady offset under steady state is the best way to define it.

Dynamic error, on the other hand, concerns how the measurement responds to changes. It includes lag, dead time, and the finite response time as the input changes, so the reading may temporarily deviate while the system catches up. Saying static error changes with temperature shifts the focus to drift, which is not the defining feature of static error. Saying dynamic error is a random variation describes noise, which is not the core notion of dynamic error either.