10
ENG
ir33+ VCC
+040000058 - rel. 1.2 - 15.02.2018
3.1.2 Control
confi guration
The main control values used are:
•
the temperature read by the control probe S1
•
the set point, defi ned by parameter St.
If the compressor is off , it will restart when S1 > St + rd, at the soft-start frequency defi ned by parameter cSc.
After a few seconds, the PID control algorithm manages the correct speed based on the temperature read by
the control probe S1, remaining inside the operating range defi ned by frequencies cmf and cMf.
Temperature
PID regulation
Frequency
MIN freq.
MAX freq.
St+rd
csc
Start freq.
Fig. 3.a
Key
St = Set point (target temperature)
rd = Temperature control diff erential
csc = Soft-start frequency
The PID control algorithm can be adapted to suit the needs of the application using the following parameters:
•
cPr = PID control proportional term
•
ctl = PID control integral term
•
cdt = PID control derivative term
The default values are suitable and safe for starting any application the fi rst time. When adapting the settings,
it is recommended to change one parameter at a time and then verify behaviour of the application in a
controlled environment.
If the compressor is on, it stops when the temperature read by the control probe S1 falls below the set point
St for a time equal to cct.
•
If cct is set to 0, the compressor stops immediately when reaching S1 = St.
•
If cct is set to 255, the compressor never stops.
rd
Temperature
St
ON
VCC Compressor
Status
OFF
AL / cct
Fig. 3.b
Key
AL = Low temperature alarm threshold
St = Set point
rd = Temperature control diff erential