Designates the difference between the actual value of a control variable and the actual value of a reference variable.When using a regulator controller with a fixed set point, the control deviation describes the difference between the actual value and the setpoint. In light of the behaviour in the case of faults or erratic changes to the reference variable, a distinction is made between:
- a constant control deviation as the control deviation present in the steady state and
- a temporary control deviation, which occurs during the transition from one steady state to another.
(DIN 19 226).