Control System - Electra CN 25 DCI Service Manual

11.

CONTROL SYSTEM

11.1 General Functions and Operating RulesThe 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 man-
ual.
11.1.1 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 a
parameter 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.
11.1.2 Compressor Frequency Control
11.1.2.1 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 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
Indoor Fan Speed
Low
Medium
High
Turbo
Auto
NLOAD limits as a function of power shedding:
Mode
Cooling
Heating
11.1.3 Target Frequency Setting
11.1.3.1 Target Frequency Setting for DCI 25/35/50/60/72Z
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:
Up to SW 35V12
NLOAD
<10 0
10 MinFreqC in cool OR MinFreqH in heat mode
NLOAD (as long it is in the allowed range, if not, the MinFreqC or Max FreqC in
11-126
cool mode OR MinFreqH or MaxFreqH in heat mode will be selected).
127 MaxFreqC in cool OR MaxFreqH in heat mode.
SM CN 1-E.1 GB
Maximum NLOAD Cooling
MaxNLOADIF1C
MaxNLOADIF2C
MaxNLOADIF3C
MaxNLOADIF4C
MaxNLOADIF5C
Power Shedding OFF
No limit
No limit
Target Frequency [Hz]
CONTENT
CONTROL SYSTEM
Maximum NLOAD Heating
MaxNLOADIF1H
MaxNLOADIF2H
MaxNLOADIF3H
MaxNLOADIF4H
MaxNLOADIF5H
Power Shedding ON
Nominal Cooling
Nominal heating
11-1