Mitsubishi Electric PURY-P120Y(T)HMU-A, Service Handbook

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[
VII
Control ]
- 132 - HWE0803A 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 setting of outdoor unit can be verified by using the self-diagnosis switch (SW1).
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.
-2- Startup sequence rotation
ΠAt the initial startup, outdoor units start up in the order of "OC and OS."
ΠStartup sequence rotation is performed while all the indoor units are stopped. (Even after two hours of operation, startup se-
quence rotation is not performed while the compressor is in operation.)
In a system with multiple outdoor units (OC and OS), when the integrated operation time of the unit in operation (either OC or
OS) reaches one hour during a cooling operation at low outside temperature, that unit will stop and the other unit will go into
operation.
Œ
Refer to [-10-Control at Initial Start-up] for the initial startup.
Œ
Performing startup sequence rotation does not change the basic operation of OC and OS. Only startup sequence is changed.
Œ
Startup sequence of the outdoor units can be checked with the self-diagnosis switch (SW1) on the OC.
-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).
Display
SW1
ON
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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
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