FB_BA_NgtCol

This function block FB_BA_NgtCol is used to cool down rooms that have been heated up during the day with cool outside air at night. The summer night cooling function serves to improve the quality of the air and to save electrical energy. Electrical energy for cooling is saved during the first hours of the next summer day.

The start conditions for the summer night cooling are defined by parameterizing the FB_BA_NgtCol function block. The function block can be used to open motor-driven windows or to switch air conditioning systems to summer night cooling mode outside their normal hours of operation.

Switching conditions

The following conditions must be met for activation of summer night cooling:

The function block itself is enabled (bEn = TRUE).
The outside temperature is not too low (fTOts > fTOtsLoLmt).
The outside temperature is sufficiently low compared to the room temperature (fTRm - fTOts) > fSwiOnDiffT.
The room temperature is high enough to justify activating summer night cooling. fTRm > fSpRm + fTRmHys.

Under the following conditions the summer night cooling is disabled:

The function block itself is disabled (bEn = FALSE).
The outside temperature is too low fTOts < (fTOtsLoLmt - 0.5).
The outside temperature is too high compared to the room temperature (fTRm - fTOts) < fSwiOffDiffT.
The room temperature is lower than the setpoint. fTRm ≤ fSpRm.

Inputs

VAR_INPUT
  bEn          : BOOL;
  fTOts        : REAL;
  fTRm         : REAL;
  fSpRm        : REAL;
  fTOtsLoLmt   : REAL;
  fTOtsHys     : REAL;
  fTRmHys      : REAL;
  fSwiOnDiffT  : REAL;
  fSwiOffDiffT : REAL;
END_VAR

Name	Type	Description
bEn	BOOL	Enable function block.
fTOts	REAL	Outside temperature [°C]
fTRm	REAL	Room temperature [°C]
fSpRm	REAL	Room temperature setpoint
fTOtsLoLmt	REAL	Lower outside temperature limit [°C]; prevents excessive cooling.
fTOtsHys	REAL	Hysteresis for minimum outside temperature [°K]. This hysteresis, which at the lower end is internally limited to 0.5 K, is intended to prevent bQ from switching, if the outside temperature fluctuates precisely around the value of rTOtsLoLmt.
fTRmHys	REAL	Hysteresis for the room temperature [K]. This hysteresis, which at the lower end is internally limited to 0.5 K, is intended to prevent unnecessary switching of bQ, if the room temperature fluctuates precisely around the setpoint rSpRm.
fSwiOnDiffT	REAL	Difference between the room temperature and the outside temperature, from which summer night cooling is enabled [K].
fSwiOffDiffT	REAL	Difference between the room temperature and the outside temperature, from which summer night cooling is locked [K]. An internal check is carried out to ensure that the difference between (fSwiOnDiffT - fSwiOffDiffT) > 0.5.

Outputs

VAR_OUTPUT
  bQ  : BOOL;
END_VAR

Name	Type	Description
bQ	BOOL	Summer night cooling On

Requirements

Development environment	Required PLC library
TwinCAT from v3.1.4024.22	Tc3_BA2 from v5.2.5.0