Mitsubishi Electric City Multi PFAV-P500VMH-E, Service Handbook

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[
VIII
Control ]
- 71 -
HWE07150 GB
[2] Controlling the Outdoor Unit
-1- Outline of Control Method
ΠThe outdoor units are designated as OC and OS in the order of capacity from large to small (if two or more units have the
same capacity, in the order of address from small to large).
ΠThe OC determines the operation mode and the control mode, and it also communicates with the indoor units.
ΠThe OS exercises autonomous distributed control (over defrost, error detection, and actuator control etc.) according to the
operation/control mode signals that are sent from the OC.
ΠHowever, compressor capacity control and outdoor fan capacity control are performed by the OC.
ΠThere is no change to the state of the OC after the rotation is performed. (The compressor and fan may enter a stop state
when the OC is in the thermo-ON state.)
-2- Startup sequence rotation
ΠAt the initial startup, outdoor units start up in the order of OC to OS, but after two or more hours of operation, the startup
sequence changes to OS to OC (Rotation control).
ΠRotation control is performed while all of the indoor units are stopped. (When the compressor is in operation, the order does
not change even after two hours of operation.)
ΠIn addition to the times described above, rotation control may also be performed during the initial startup.
ΠThe self-diagnosis switch (SW1) can be used to check whether each outdoor unit is functioning as an OC or OS.
-3- Initial Control
ΠWhen the power is turned on, the initial processing of the microcomputer is given top priority.
ΠDuring the initial processing, control processing of the operation signal is suspended. (The control processing is resumed after
the initial processing is completed. Initial processing involves data processing in the microcomputer and initial setting of each
of the LEV opening. This process will take up to 5 minutes.)
ΠDuring the initial processing, the LED monitor on the outdoor unit's control board displays S/W version -> refrigerant type
-> heat pump -> cooling only and capacity -> and communication address in turn every second.
-4- Control at Start-up
ΠThe upper limit of frequency during the first 3 minutes of the operation is 50 Hz.
ΠWhen the power is turned on, normal operation will start after the initial start-up mode (to be described later) has been com-
pleted (with a restriction on the frequency).
SC
OC
(maximum
capacity)
OC
IC1
Indoor unit
RC
Outdoor unit
Signal flow
Display SW1
ON
1 2 3 5 4 6 7 8 9 1 0
The unit is designated as the OC: “oc” appears on the display.
The unit is designated as OS: “oS” appears on the display
Display SW1
OC→OS: “oc” and the OC address appear alternately on the display.
OS→OC: “oS” and the OS address appear alternately on the display.
ON
1 2 3 5 4 6 7 8 9 1 0