µRack
Cod. CAREL +03P220431 rel. 2.2 dated 10/02/12
19
LIFO rotation (no rotation parameter r20=0)
The first fan that to start will be the last to stop.
•
Start: Fan1, Fan2, Fan3, Fan4.
•
Stop: Fan3, Fan3, Fan2, Fan1.
FIFO rotation (parameter r20=1)
The first fan that to start will be the first to stop.
•
Start: Fan1, Fan2, Fan3, Fan4.
•
Stop: Fan1, Fan2, Fan3, Fan4.
The rotation of the fans is implemented when called.
Various fan parameters
In the event of a discharge probe fault or not connected alarm, parameter /12 sets the number of fans that are forced on.
5.3
Inverter management
The fan controller is enabled by parameter /10.
A minimum limit value can be set for the inverter (parameter r29), as a percentage.
To assist the start of the inverter, a time can be set, expressed in seconds, during which the inverter is forced on at 100% at startup before proceeding with the normal
regulation. This parameter is called “Speed Up Time” (parameter r27).
Management of the fans slaved to the compressors
Parameter “/13” defines whether the fans can be activated independently or whether at least one compressor must be on. This is used to prevent the condenser fans
operating with high outside temperatures work when no compressor is operating. Typical application: cold rooms cold stores.
Parameter “/13” default = 0 (independent control).
Inverter control
Proportional band
This control requires the inverter set point STPI to be set (parameter r18 ), plus an inverter differential RBI (parameter r19).
If the value measured by the discharge probe is less than or equal to the value of the inverter set point, the inverter output will be 0.
Between the inverter set point STPI and point C (set point + differential), the value of the inverter output will be proportional to the value read by the discharge probe,
and in any case not less than the minimum inverter output MinIn. If the value measured by the discharge probe is greater than or equal to the inverter set point +
differential, the output will be at the maximum value. The control is not associated with any fan and can work without fans being configured.
Proportional control, set by parameter r21, may be proportional only (parameter r21=0) or propor integral (parameter r21=1).
Key:
STPI
Fan inverter set point
RBI
Inverter differential
Min In
Minimum inverter opening
C
Fan set point + differential
Key:
RB
Fan differential
RBI
Inverter differential
STPM
Discharge set point
STPI
Inverter set point
C
Inverter set point + inverter differential
B
Discharge set point + Fan differential
Min In
Minimum value of the inverter control output
Fig.5.d
Fig. 5.c
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