Special Control; Outdoor Unit Rotation - Daikin RXQ12AHR Service Manual

Special Control

7. Special Control
7.1

Outdoor Unit Rotation

In the case of multi-outdoor-unit system, this outdoor unit rotation is used to prevent the
compressor from breaking down due to unbalanced oil level between outdoor units.
Details of outdoor unit rotation
In the case of multi-outdoor-unit system, each outdoor unit is given an operating priority for the
control.
Outdoor unit rotation makes it possible to change the operating priority of outdoor units.
Thus, the system becomes free of compressors that stop over an extended period of time at the
time of partial loading, preventing unbalanced oil level.
Timing of outdoor unit rotation
OR
 After oil return operation
 At the beginning of the startup control
 There are outdoor units that stop operation.
 Low pressure of all outdoor units in operation is less than 0.25 MPa.
Example) The following diagram shows outdoor unit rotation in combination of 3 outdoor units.
Startup
control
Outdoor unit
rotation
Cooling
Master Slave 1 Slave 2
Priority
2
Note(s)
1. "Master unit", "slave unit 1" and "slave unit 2" in this section are the names for installation.
They are determined in installation work, and not changed thereafter. (These names are
different from "master unit" and "slave unit" for control.)
The outdoor unit connected the control wires (F1 and F2) for the indoor unit should be
designated as master unit.
Consequently, The LED display on the main PCB for "master unit", "slave unit 1" and "slave unit
2" do not change.
90
Normal operation
Master Slave 1 Slave 2
Priority Priority Priority
1 2 3
·
There are outdoor
units that stop
operation.
OR
·
Low pressure of all
outdoor units in
operation < 0.25 MPa.
Normal operation
Priority Priority
3 1
Oil return
operation
Normal operation
Outdoor unit
rotation
Normal operation
Master Slave 1 Slave 2
Outdoor unit
Priority
rotation
1
Master Slave 1 Slave 2
Priority Priority Priority
3 1 2
Priority Priority
2 3
Part 4 Functions and Control
SiAF341904E