Mitsubishi Electric PLA-SM71EA2 Service Manual page 34

Operation pattern
1 [Back-up function only]
Start operation
Main
unit
Run
IC-1
Sub
unit
Stop
IC-2
2 [Rotation function] & [Back-up function]
Start operation
Main
unit
Run
IC-1
Sub
unit
Stop
IC-2
1–28 days
(Ex:When the request code number is 1 day, each unit operates alternately in daily cycle.)
Note:
· When the unit is restarted to operate after turning off the power or operation OFF status, the unit which was operating will
start operation.
· To operate the main unit, refer to "13-6. ROTATION SETTING" and set again.
(2) 2nd stage cut-in function
• Outline of functions
· When the 1st unit cannot supply with sufficient capacity for exceptionally high-demand conditions and the actual room tem-
perature reaches set point (*), the 2nd unit starts operation in conjunction with the 1st unit.
· Once the actual room temperature goes down to 4°C below set point (*), the 2nd unit stops operation automatically.
(* set point = set temperature by R/C (remote controller) + 4, 6, 8°C (selectable) )
· Number of operating units is determined according to the room temperature and set point.
· When room temperature reaches higher than set point, standby unit starts. (2 units operation)
· When room temperature falls below set point −4°C, standby unit stops. (1 unit operation)
• System constraint
· This function is available only in cool mode.
E.g.) Set temp. by R/C = 20˚C
Set point = 26˚C
26˚C 2nd unit Cut-in
4˚C
22˚C 2nd unit Cut-out
20˚C
OCH784
Error occurs on main unit.
Main Sub
Abnormal condition
Run
Error occurs on main unit.
Main Sub Main Sub Main
Stop Run
Run Stop
1–28 days
[2nd stage cut-in function]
Main
unit
IC-1
Sub
unit
IC-2
Fig. 1
Main
unit
Sub
OC : Outdoor unit
Abnormal condition
IC : Indoor unit
RC : Wired remote controller
Run
Room temp. ] Set point
Start operation Sub unit start operation
Run
Stop Run
34
Refrigerant address Refrigerant address
"00" "01"
OC-2
OC-1
3(2)
3(2)
IC-2
IC-1
2
2
RC
Room temp. < Set point −4:
Sub unit stop
Stop
Sub
unit