About Backup Operation During Maintenance Work - Panasonic 2WAY Multi Technical & Service Manual

(2) About backup operation during maintenance work

● What is backup operation?
In the W MULTI series, multiple outdoor units are connected to the same refrigerant tube as shown in Figure 1.
Therefore, even during maintenance work of an outdoor unit, the other outdoor unit not required in maintenance
work can be used to keep the indoor operating conditions. This is called a backup operation.
● Backup operation procedure
To perform backup operation, the outdoor unit for maintenance work (hereafter referred to as "target outdoor
unit") must be cut off from the system using the following procedure. Review content of the maintenance work
and then select the most suitable method.
Also, after the maintenance work is fi nished, always refer to [System recovery procedure] and then return the
system to its normal state.
[Backup operation procedure]
To turn off power of target outdoor unit and then perform maintenance work (basic operation during inspection
of outdoor unit)
<<Important>>
This is the basic operation performed during inspection work. If this operation is not performed and the power
of the outdoor unit is turned off, this will cause system fault and prevent backup operation to be carried out,
and serious malfunction will occur. If this happens, see [System recovery procedure] to recover the system, and
then once again use the following procedure to perform setup. Automatic backup operation will kick in.
*1) Sometimes all outdoor units may stop. If there is operation input, outdoor units other than the target one will
start operation again after approximately fi ve minutes. (For details on the settings, see the next item.)
*2) Always carry out the following three tasks.
Check to make sure <<Step 2>> is fi nished. If the shutoff valve is opened, refrigerant will fl ow from the
other outdoor unit to the target outdoor unit, causing serious malfunction.
After three minutes has elapsed from completion of <<Step 1>>, check to make sure the outdoor main
board displays "       " and then perform this operation. If you turn off the power immediately
after performing "STOP" setting, the entire system will stop. (Backup operation cannot be performed.) If
this happens, see [System recovery procedure], recover the system, and then start over again starting from
<<Step 1>>.
There will not be any problem whether the circuit breaker of the outdoor unit in <<Step 3>> is ON or OFF.
Select one of them according to the work required.
<<Step 1>>
On the outdoor main board of the target outdoor unit,
set the STOP switch (S001) to "STOP". *1
<<Step 2>>
(After confi rming that the engine of the target outdoor
unit is stopped) close the valves of refrigerant gas tube,
refrigerant gas liquid tube, and balance tube.
<<Step 3>>
On the outdoor main board of the target outdoor unit,
set the STOP switch (S001) to "STOP". Wait for three
minutes or more and then turn off the circuit breaker of
the target outdoor unit. *2
Start maintenance work.
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