Pixsys ATR 621 series - Page 25

ATR 621 - User manual 25
 =  Alarm1 selection (Cooling)
     : Proportional band multiplier
 : Overlapping / Dead band
 : Cycle time Cooling
Parameter    (that ranges from 1.00 to 5.00) determinates the proportio-
nal band for cooling action, according to the formula:
- Proportional band for cooling action: =   *     
In this way it is possible to have a proportional band for cooling action
that will be equal to heating proportional band if
     = 1.00, or 5 times
greater if      = 5.00.
- Integral and Derivative time are the same for both actions.
Parameter  establishes the overlapping (in percentage) betwe-
en the two actions. For installations where heating and cooling outputs
cannot be activated at the same time, a Dead band will be con gured
( ≤ 0), viceversa an overlapping will be con gured ( > 0).
Figure below shows an example of double action PID (heating-cooling)
with  = 0 and  = 0.
SPV
PV
ATTIVO
ACTIVE
ATTIVO
ACTIVE
   x      (COOL)
 < 0
   (HEAT)
COMMAND OUTPUT (HEAT)
ALARM OUTPUT (COOL)
SPV
PV
ATTIVO
ACTIVE
ATTIVO
ACTIVE
   x      (COOL)
 = 0
   (HEAT)
COMMAND OUTPUT (HEAT)
ALARM OUTPUT (COOL)