Service manual

11-1
CONTROL SYSTEM
SM HADDCI 1-A.2 GB
11. CONTROL SYSTEM [HAD007, HAD009, HAD012]
11.1 Electronic Control
11.1.1 General Functions and Operating Rules
The DCI software is fully parametric.
The parameters values are given in the last section of this control logic chapter of the service
manual.
11.1.2 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.
11.1.3 Compressor Frequency Control
11.1.3.1 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
Low Max NLOADIF1C 127
Medium Max NLOADIF2C 127
High Max NLOADIF3C 127
Turbo Max NLOADIF4C 127
Auto Max NLOADIF5C 127
11.1.3.2 Target Frequency Setting
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:
1. For S/W 37V3 and lower ( For 453031000R Controller):
NLOAD Target Frequency
127 Maximum frequency
10 < NLOAD < 127 Interpolated value between minimum and maximum frequency
10 Minimum frequency
0 Compressor is stopped
Target frequency limits as a function of outdoor air temperature (OAT):
OAT Range Cool mode limits Heat mode limits
OAT < 6
MaxFreqAsOATC
No limit
6 ≤ OAT < 20 MaxFreqAsOAT1H
20 ≤ OAT < 26
MaxFreqAsOAT2H
26 ≤ OAT No limit
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