FB_BA_NgtCol

Functional description

With this function block, rooms that were heated up on the day before can be cooled down during the night using cool outside air. 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 parameterising the FB_BA_NgtCol function block. The 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.

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 (rTOts > rTOtsLoLmt).
• The outside temperature is sufficiently low compared with the room temperature (rTRm - rTOts) > rSwiOnDiffT.
• The room temperature is such that it is not worth switching on summer night cooling. rTRm > rSpRm + rTRmHys.

Under the following conditions the summer night cooling is disabled:

• The function block itself is disabled (bEn = FALSE).
• The outside temperature is too low (rTOts < rTOtsLoLmt).
  
• The outside temperature is too high compared with the room temperature (rTRm - rTOts) < rSwiOffDiffT.
  
• The room temperature is lower than the setpoint. rTRm≤rSpRm.

VAR_INPUT

bEn          : BOOL;
rTOts        : REAL;
rTRm         : REAL;
rSpRm        : REAL;
rTOtsLoLmt   : REAL;
rTOtsHys     : REAL;
rTRmHys      : REAL;
rSwiOnDiffT  : REAL;
rSwiOffDiffT : REAL;

bEn: enable of the function block

rTOts: outside temperature [°C]

rTRm: outside temperature [°C]

rSpRm: room temperature setpoint

rTOtsLoLmt: lower outside temperature limit [°C]; prevents excessive cooling.

rTOtsHys: hysteresis for minimum outside temperature [°K]. This hysteresis, which at the lower end is internally limited to 0.5 °K, is intended to prevent jitter in bQ, if the outside temperature fluctuates precisely around the value of rTOtsLoLmt.

rTRmHys: 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 fluctuation of bQ if the room temperature oscillates precisely around the setpoint rSpRm.

rSwiOnDiffT: difference between the room temperature and the outside temperature, from which summer night cooling is enabled [°K].

rSwiOffDiffT: difference between the room temperature and the outside temperature, from which summer night cooling is locked [°K].

VAR_OUTPUT

bQ  : BOOL;

bQ: summer night cooling on

Requirements