O
PERA
T
I
ON
G
B
21
Service Manual
Ne
w
E
lectronic Cold Platform 2005
Edition
2005.03.25
Language
E
nglish
8°C
-6°C
2°C
Temperature control and alarm signalling are managed by means of three thresholds: Check Threshold
(the control strategy becomes more intensive when this threshold is exceeded); Threshold A1: when ex-
ceeded, alarm
A1 is activated; Alarm threshold A2: when exceeded, alarm A2 is activated. The values of the three thresh-
olds are parameterised in the EEPROM memory..
I
f the control temperature exceeds the Check Threshold but does not exceed the A1 Alarm threshold, a
delay time T1 is activated (parameterised in the EEPROM) before performing the next control, to prevent
the generation of alarm signals when the placement of large quantities of warm food in the freezer compart-
ment near the freezer air sensor causes unreliable transient temperature readings. At the same time an-
other time interval T2 is activated (parameterised on the EEPROM) after which, if the temperature is con-
stantly maintained between the Check Threshold and the Alarm A1 Threshold, alarm A1 is forced because
the persistence of a temperature in this range for this period of time is anyway a symptom of faulty operation
and constitutes a risk for the correct preservation of the food.
At the time of activation of alarm A1 also a time interval T3 is activated (parameterised in the EEPROM)
after which, if an alarm reset has not been executed, alarm A2 is forced, since in the situation of alarm A1
the freezer compartment is set to a temperature that may not be the same as the temperature selected by
the user. This time interval is reset also when power is restored after a mains power failure.
TH
E
RMOSTAT CONTROL.
The temperature adjustments in both the compartments are independent from each other and set individu-
ally by the relative knobs.
Freezer Compartment Adjustment:
Freezer temperature is managed by the PCB utilis-
ing the value detected by the freezer air sensor to
switch the compressor on/off.
The On / Off threshold is detected by the EEPROM
and it depends on the setting
selected by the user on the interface.
I
f the temperature measured by the freezer air sen-
sor is above the On threshold, a cooling demand is
activated thereby starting the compressor, the fan, and opening the damper; on the contrary, if the freezer
air sensor detects a temperature lower than the Off temperature, the cooling demand is deactivated.
T1 = 2 1/2 Hours
T2 = 24 Hours
T3 = 120 Hours
N. B.: The time and temperature values sho
w
n in this graph are
EE
PROM parameters and as such they are subject to modification
Summary of Contents for New electronic cold platform 2005
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