EN/07.2013/58/95
7.21. Custom 21
• Control: Same control of standard application.
• Alarm:
– Air flow alarm: this alarm is bypassed.
– External enable: the input for this alarm is logical or between A4 and A12 (air flow alarm), instead of A4.
7.22. Custom 22
Same functionality of customs 15 and 19.
7.23. Custom 23
This custom manages a Free-Air fan connected to AN-OUT V3.
Free air fan
The parameters involved are:
– M01 AUTOMATIC LEAD LAG ADDRESS: pre-set = 0
– M03 NUMBER OF PRESENT UNITS: pre-set = 1
– M188 ENABLE CONTROL OF SEQUENCING SYSTEM: pre-set = YES
The Free-Air fan control is enabled when the board is a stand alone unit (M01=0 and M03=1) or when the board is the
master unit of a master-slave system (M01=1 or 2, M03=2 and M188=NO) and when the board is the master unit of a
master-slave system (M01=1, M03=2 and M188=YES).
In a master-slave system, the control of the Free-Air fan connected to the master unit it’s independent from the lead lag
management and the temperature values used by free air fan control are always those read by the master unit probes.
In a sequencing system, the free air fan control is always disabled.
Ambient conditions
The parameters involved are:
– M39 MIN IN-OUT TEMP. DIFF. FOR FREECOOLING: pre-set = 10 °C
– M40 MIN EXTERNAL TEMP. ENABLE FREECOOLING: pre-set = -25 °C
– M41 MAX EXTERNAL TEMP. ENABLE FREECOOLING: pre-set = 60 °C
– M44 FREECOOLING OFF IF COMPRESSOR ON: pre-set = YES
Conditions to enable Free-Air fan: Conditions to disable Free-Air fan:
TI - TAE > M39
M40 < TAE < M41
(TI - TAE) < (M39 - 1) or
TAE < (M40 - 1) or
TAE > (M41 + 1)
Note that if parameter M44 is set to YES, the TAE used to control the Free-Air fan is the last TAE sampled with the
condenser fan on.
Fan regulation
The parameters involved are:
– M138 FREE AIR FAN MINIMUM SPEED: pre-set = 0 %
– M139 FREE AIR FAN MAXIMUM SPEED: pre-set = 100 %
When the Free-Air fan is blocked or the unit is in a state different from on, the Free-Air fan is disabled.
When the unit is in emergency state and TAE > TI, the Free-Air fan speed is set to the minimum speed (M138).
In a master-slave system, if the master and the slave units are in a state different from on and emergency, the Free-Air
fan connected to the master unit is disabled.
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