Difference between the setpoint and actual value of the control variable. It is positive if the actual value is smaller than the desired value. A differentiation is made between:
- a residual control error as the control error present in the steady state of the control variable and
- a temporary control error, which occurs during the transition from a steady state to another after a change of the disturbance variables or guide variables. The reference variable is the setpoint of the control variable in the new steady state (EDIN 19 226 T 5).