Control System - Electra PXD 25 DCI Service Manual

10.

CONTROL SYSTEM

10.1 General Functions and Rules (for single split models)
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.
10.2
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.
10.3
Compressor Frequency Control
10.3.1 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
Low
Medium
High
Turbo
Auto
NLOAD limits as a function of power shedding:
Mode
Cool
Heat
Service Manual - PXD DCI
Maximum NLOAD Cooling
Max NLOADIF1C
Max NLOADIF2C
Max NLOADIF3C
Max NLOADIF4C
Max NLOADIF5C
Power Shedding OFF
No limit
No limit
Revision Y05-01
CONTENT
CONTROL SYSTEM
Maximum NLOAD Heating
127
127
127
127
127
Power Shedding ON
Nominal Cooling
Nominal Heating
10-1