Terms Used Interchangeably for Process Control

• attenuation filtering

• dead band backlash

• control interval cycle time execution time

• delay time dead time

• derivative action rate action

• derivative time rate time

• digital filter process variable filter signal filter

• estimator inferential measurement intelligent sensor

• integral action reset action

• integral time reset time

• lag time time constant

• open loop gain plant gain process gain

• open loop time constant plant time constant process time constant

• resolution sensitivity sticktion stick-slip

• steady state gain static gain

• total loop dead time system dead time plant dead time process dead time

• upset disturbance load

Definitions of Process Control Terms

See ANSI/ISA-51.1 Process Instrumentation Terminology for a comprehensive list of terms used in automation systems.

action

relative direction of change in output for a change in input ("direct" for changes in same direction and "reverse" for changes in opposite direction)

A/D

analog-to-digital converter typically used to convert an analog input to its digital value with a resolution of 0.05 percent for a 12-bit converter with one sign bit

attenuation

reduction in amplitude of an oscillation between two operating points or two frequencies as a result of smoothing by a filter time constant in the measurement or by process time constant from a mixed volume.

automatic mode

PID controller mode to enable its set point to be locally adjusted by the operator (also known...