11
ENG
ir33+ VCC
+040000058 - rel. 1.2 - 15.02.2018
In order to protect the refrigerated products, management of the two temperature thresholds overlies normal
control:
AL = LOW temperature alarm threshold;
when the temperature read by the control probe S1 is lower than the threshold AL, the controller immediately
stops the compressor.
AH = HIGH temperature alarm threshold;
when the temperature read by the control probe S1 is greater than the threshold AH, the controller activates
a compressor pull down cycle.
See the paragraph “Pull down”.
St
St + rd
AL
AH
Compressor OFF
Cooling capacity / compressor speed modulation
Temperature
Time
Compressor status
ON
OFF
Time
cct
Compressor at minimum speed (frequency)
Compressor ON at MAXIMUM speed
Fig. 3.c
Key
AH = High temperature alarm threshold
St + rd = Set point + diff erential
St = Set point
AL = Low temperature alarm threshold
Code Parameter
UOM
Dis.
Def.
Max
Min
St
Set point
°C/°F
F
-20
200
50
rd
Set point diff erential
°C/°F
F
1
20
0.1
cPr
PID control proportional term
Hz/°C
C
2
800
0
ctI
PID control integral time
s
C
120
999
0
cdt
PID control derivative time
s
C
0
255
1
cSc
Soft-start frequency
Hz
C
53
255
0
cmF Minimum control frequency
Hz
C
52
255
0
cMF Maximum control frequency
Hz
C
100
255
0
cct
Compressor cut-off time
Min.
C
1
255
0
cPd
Compressor maximum pull down time
Hours
C
1
240
0
AH
High temperature alarm threshold
°C/°F
F
-14.0
200
-50.0
AL
Low temperature alarm threshold
°C/°F
F
-26.0
200
-50.0
Tab. 3.b