Electra DELTA 25, Service Manual

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11-1
CONTROL SYSTEM
Revision Y05-01 Service Manual - Delta DCI
11. CONTROL SYSTEM
11.1 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.
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 (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 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:
NLOAD Target Frequency
127 Maximum frequency
10 < NLOAD < 127 Interpolated value between minimum and maximum frequency
10 Minimum frequency
0 Compressor is stopped