User Manual

Control concept
Closed-loop control strategy
5
CM110664en_07 91 | 353
[Inv] of the output signal is required, e.g., for air dampers. The outside air and
exhaust air damper must close in response to an increasing heating demand.
The inversion of the manipulated variable affects only the output signal [Yctr]
and not the action of the controller.
Sequence controller
Sequence controllers are used primarily in ventilation and air conditioning
systems to control the temperature and humidity. Other applications are also
possible, e.g., in heating systems.
Each controlled aggregate functional unit incorporates a universal PID
controller function block, PID_CTR, as a sequence-controller element.
The statements made about the universal PID controller also apply to the use
of the PID_CTR function block as a sequence-controller element.
The sequence-controller elements coordinate their own interaction
independently. Interaction is coordinated with coordination signals [FmHigher]
and [ToLower], which are mutually exchanged by adjacent sequence-controller
elements. This is the only link between the sequence-controller elements. This
process allows the setting of individual parameters for each individual
controller or aggregate, and hence effective optimization of the entire plant.
Properties and design of sequences and sequence controllers:
● Each sequence may include any number of elements
● The setpoint for each element of a sequence can be defined separately, but
set points must not be allowed to decrease in the direction from the heating
sequence to the cooling sequence.
● The setpoint for energy recovery can be selected and is either at the
midpoint between the setpoint of the first heating element and that of the
first cooling element, or (depending on the method of energy recovery
currently possible), it may be equivalent to the setpoint of the first heating
element (if the extract air temperature is higher than the outside air
Inversion [Inv]