Service manual

12-1
CONTROL SYSTEM
SM DNGDCI 2-E.1 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.
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 the indoor to the outdoor by communication, and represented by a parameter called
‘NLOAD’. NLOAD is an integer number with values between 0 and 127, and represents the heating
or cooling load indicated by the indoor unit.
12.1.1 Compressor Frequency Control
12.1.1.1 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 LOAD
calculation, the indoor fan speed, and the power shedding function.
NLOAD limits as a function of indoor fan speed:
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
CONTENT