Mitsubishi Electric PUHY-P250YNW-A Service Handbook page 108

[5-2 Outdoor Unit Control ]
(5) Running/Stopping the Units on Rotation
Indoor units whose SW9 (Normal/Local switching switch) is set to "Local" will not be able to accept the Run/Stop signal from
the control unit and will not operate properly. After the unit whose SW9 is set to "Local" is operated or stopped from the MA
remote controller, the operation status needs to be changed back to the original status, and the SW9 setting needs to be set
back to "Normal."
If an attempt is made to Run/Stop the indoor unit whose SW9 is set to "Normal", the following types of errors may happen.
Example 1 Backup units are not rotated when the system rotation timer has reached 480 hours.
Example 2 The backup unit does not go into operation when a unit in the group detects an error.
These symptoms can be solved by bringing the stopped unit into operation. By doing so, although all the units will temporarily
operate, the rotation function will remain effective.
(6) When an Error Occurs
If an error is detected by a unit or a communication failure between the systems in the group while the rotation function is
enabled, the units will perform the actions as described in Table 1, and the rotation control will be temporarily stopped.
When the starting conditions are met, this function will be resumed, and the rotation sequence and the system rotation timer
count effective at the time of error will be kept.
Table.1 Operation of Units during an Error
Control unit Backup unit
Regular unit
Other units Backup unit
Regular unit
*1. The backup unit will automatically resume its operation when periodical communication from the control unit is lost.
(7) Rotation Function Test Run Mode
Proper operation of the rotation function can be checked in a short time using the rotation function test run mode.
Rotation function test run mode can be initiated by starting the control unit in the test run mode (via MA remote controller).
In this mode, the system rotation timer setting is reduced to approximately three minutes (from the usual 480 hours), and the
test run will automatically end when the control unit is rotated to the backup unit.
At the completion of the test run mode, the system rotation timer setting goes back to 480 hours, and this function will remain
effective.
Important Notes on Rotation Control
All the units in the system using the rotation function must be the same capacity and installed within the same area to be
cooled.
Check that the items to be cooled are not affected no matter which unit stops when designated as a backup unit.
The backup unit automatically goes into operation only when there is a problem with other units in the group. It will not auto-
matically go into operation even if the heat load increases.
The control unit cannot perform a test run while the system rotation function is performed. Disable the system rotation control
function to perform a test run.
If multiple units are grouped with an MA remote controller or an AE-200E controller, this control function will not work properly.
BS_05_C
Rotation status A unit in the group made an abnor-
Goes into operation
Sends a startup signal to the back-
up unit
Goes into operation by receiving a
signal from the control unit
Sends its own error status to the
control unit
Communication failure between
mal stop.
Goes into operation
Sends a startup signal to the back-
up unit
1) Goes into operation by re-
2) Goes into operation
systems
ceiving a signal from the con-
trol unit
*1
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