Service manual

12-1
CONTROL SYSTEM
SM SX DCI 1-A.3 GB
12. CONTROL SYSTEM
12.1 General Functions and Operating Rules
The DCI software is fully 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.
12.1.1 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 mode
avoiding 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 it
represents the heat or cool load felt by the indoor unit.
12.1.2 Compressor Frequency Control
12.1.2.1 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 LOADcalculation,
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
Indoor Fan Speed Maxium NLOAD Cooling Maxium 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
12.1.3 Target Frequency Setting
12.1.3.1 Target Frequency Setting for DCI 50/60/72Z
The compressor target frequency is a function of the NLOAD number sent from the indoor
controller and the outdoor air temperature.
Basic Target Frequency Setting:
NLOAD Target Frequency
127 Maximum Frequency
10<NLOAD<127 Interpolated value between minimum and maximum frequency
10 Minimum frequency
0 Compressor is stopped
CONTENT