12-1
CONTROL SYSTEM
SM XLFDCI 1-A.1 GB
12 CONTROL
SYSTEM
12.1
General Functions and Operating RulesThe DCI software parametric.
All the model dependent parameters are shown in Blue color and with Italic style [
parameter
].
The parameters values are given in the last section of this control logic chapter of the service
manual.
System Operation Concept
The control function is divided between indoor and outdoor unit controllers. Indoor unit is the system
‘Master’, requesting the outdoor unit for cooling/heating capacity supply. The outdoor unit is the
system ‘Slave’ and it must supply the required capacity unless it enters into a protection modeavoiding
it from supplying the requested capacity.
The capacity request is transferred via indoor to outdoor communication, and is represented by
aparameter called ‘NLOAD’. NLOAD is an integer number with values between 0 and 127, and
itrepresents the heat or cool load felt by the indoor unit.
Compressor Frequency Control
NLOAD setting
The NLOAD setting is done by the indoor unit controller, based on a PI control scheme.
The actual NLOAD to be sent to the outdoor unit controller is based on the preliminary LOAD
calculation, the indoor fan speed, and the power shedding function.
NLOAD limits as a function of indoor fan speed:
Indoor Fan Speed Maximum NLOAD Cooling Maximum NLOAD Heating
IndoorFan Speed
Maximum NLOAD Cooling
Maximum NLOAD Heating
Low
MaxNLOADIF1C
MaxNLOADIF1H
Medium
MaxNLOADIF2C
MaxNLOADIF2H
High
MaxNLOADIF3C
MaxNLOADIF3H
Turbo
MaxNLOADIF4C
MaxNLOADIF4H
Auto
MaxNLOADIF5C
MaxNLOADIF5H
NLOAD limits as a function of power shedding:
Mode
Power Shedding OFF
Power Shedding ON
Cooling
No limit
Nominal Cooling
Heating
No limit
Nominal heating
Target Frequency Setting
Target Frequency Setting for GC 9 / 12
The compressor target frequency is a function of the NLOAD number sent from the indoorcontroller
and the outdoor air temperature.
Basic Target Frequency Setting:
CONTENTS
