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MC2-FC mode FC
Document no.:200064 Version: 1.5
Page 6 of 44
1.3 Phases and cooling
The controller functions in 3 phases. These phases mainly relate to the control of the mechanical
cooling (fluid valve and a suction valve, where relevant).
Cool phase: In this phase, the cell starts mechanically cooling when the control temperature exceeds
the temperature set point + temperature differential. The cooling stops when the temperature set
point is reached. Cell cooling is only started if it doesn’t exceed the maximum total cooling capacity
of the cooling cells (P804). For that reason, the cooling capacity of every cell must be defined before
the cool phase (P803). Due to this maximisation, cells must sometimes wait until cooling capacity
becomes available.
Store phase: For the cells in this phase, a regular store cycle is running in which it is the turn of each
cell to cool mechanically once per cycle until the control temperature has reached the temperature
set point. It is possible to define the time between two successive cycles (P307). As many cells as
possible with a cooling demand will be started if this is permitted by the maximum number of cooling
cells in store phase (P308). The sequence in which the cells in the cycle start cooling is determined
by the network number. This uses a sequence of ascending network number, but the network number
with which a cycle starts rotates every cycle. The first cycle starts, for example, with cell number 1,
the second cycle with cell number 2, and so on.
When a cell cannot be started – for example, because it is defrosting – there is a slight deviation
from the sequence. However, if a subsequent cell can be started, it is indeed started to avoid the loss
of cooling capacity. The store phase is very suitable for controlling several cells with a limited
compressor capacity and a limited number of compressor starts.
Standby phase: In this phase, the cell only cools (mechanically) if that is required in order to deliver
hotgas to another cell that is waiting for a hotgas defrost action. The other functions of this cell
(defrost, heating, humidification and automatic ventilation) are blocked. This phase can be released
or blocked (P901).
1.4 Heating
The heating (Heating relay function) is switched on when the control temperature drops below the
current temperature set point - differential. The heating stops when the current temperature set
point has been reached.