System Rotation Control Instructions - Mitsubishi Electric PUHY-P250YNW-A Service Handbook

[5-2 Outdoor Unit Control ]
5-2-19

System Rotation Control Instructions

1. General Descriptions
Each group can consist of a maximum of 5 systems and a minimum of 2 systems.
With the use of this control function, one system in a given group serves as a backup and remains stopped.
The unit designated as the control unit (System 1 in Figure 1) sends command signals to other units in the group to start or
stop, and rotates the backup unit every 480 hours.
Rotation sequence is in the ascending order of address, starting from the lowest address after the control unit address.
(e.g., System 2 -> System 3 -> System 4 -> System 5 -> System 1 in Figure 1 below)
If other units in the group detect an error or if there is a communication failure between the systems, this control is terminated,
and the backup unit goes into operation.
CAUTION
To enable this control function, the following wiring and settings are required at installation.
1) Daisy-chain terminals M1 and M2 on the terminal block for transmission line for centralized control (TB7) on all
applicable outdoor units.
Move the power jumper connected to CN41 to CN40 on only one of the outdoor units.
To supply power to the outdoor unit from a power supply unit, leave the power jumper connected to CN41as it
is (factory setting).
2) Check that the label on the indoor unit circuit board reads KE90D352, if it does not, replace the circuit board.
3) Set the SW1-9 and SW1-10 on indoor units as follows to enable the external input: (SW1-9: ON; SW1-10: OFF).
4) Assign sequential addresses to the units as shown below (Figure 1 and 2).
(Only use odd numbers for the 10HP system.)
5) Make the rotation group settings by setting the appropriate switches on the outdoor units.
<Refer to "(1) Rotation Group Setting">
TB7 TB7
OC51 OC52
TB3 TB3
TB5 TB5
IC01 IC02
TB15 TB15
MA
System 1
(Control unit)
TB7
OC51
TB3
TB5
IC01
TB15
MA
System 1
(Control unit)
BS_05_C
OC53 OC54 OC55
IC03 IC04 IC05
MA MA
System 2 System 3
Backup unit
Figure 1 Sample 20HP system group
TB7
OC53
TB3
TB5
IC03
TB15
MA
System 2 System 3
Backup unit
Figure 2 Sample 10HP system group
OC56 OC57
IC06 IC07
MA
System 4
OC55 OC57
IC05 IC07
MA MA
System 4
OC58 OC59 OC60
IC08 IC09 IC10
MA
System 5
OC59
IC09
MA
System 5
chapter 5 -
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