Mitsubishi Heavy Industries SRRM40HENG-L, Handbook, Page: 834 / 1106

FDC-HKX
832
(l) Non-inverter compressor (CM2) overcurrent protection (Only for 224, 280 models)
If the T phase current at the secondary side of 52C2 is detected exceeding the setting value for approx. 0.5 second, the
compressor stops. The compressor is reset automatically after a 3-minute delay. If the error is detected at second time within
40 minutes after the initial detection, the unit stops with the error stop.
(m) Compressor oil level protection
When operation has continued at less than 30 Hz for 9 minutes or more, and if operation at 35 Hz per minute continued for
30 minutes or more, CM1 is stopped forcibly for 3 minutes.
However, when the frequency is at less than 30 Hz the protective control has been actuated, its control dominates.
(n) Compressor (CM1) motor lock protection
If the current value exceeds the setting value for 0.5 seconds continuously during operation, the compressor stops. If the
current detected after a 3- minute delay is less than 2A, the compressor can be started again.
If the detection is repeated 5 times within 60 minutes after the initial detection or the condition that the current does not drop
below 2A continues for 10 minutes after the first to fourth stops of compressor, the compressor stops with the error stop.
(o) Open phase protection
(i) When CM1 is on ( 20Hz) and there is L3-phase current of 0.5 A or less for 10 continuous seconds, it is determined to
be a phase fault and CM1 and CM2 are set to off.
(ii) If this is detected 5 times within 60 minutes of the first detection, an error stop is performed. If (i) is detected when CM1
is on within 10 minutes of the power being turned on, an error stop is performed on the first detection.
(iii) If the CM2 L3-phase current is 2 A or less for 5 continuous sections after CM2 has gone on, it is determined to be a
phase fault and an error stop is performed.
(p) Antiphase protection and open L2 phase at 52C1 primary side
This function monitors the phase order on the primary side of 52C1 (whenever power is turned ON) and judges L1
/
L3
/
L2
/
L3 as the antiphase (monitors simultaneously also open phase of L2 phase at the primary side). If the antiphase
continues for 2 seconds, the compressor is stopped with the error stop.
(q) Indoor unit connection number protection
If the number of indoor units on the connection exceeds the number as listed below, the compressor stops with the error stop.
Note (1) They are the numbers of units used for judgement of error for the purpose of control and not
equal to the numbers of units which can be connected.
Number of units on connection 10 units 16 units
model
Item
140 model 224, 280 model
High
Low
Heating
capacity
Heating
capacity
Standard
High
-1 +1 +2 +4
Low
Heating
capacity
Heating
capacity
Thermostat setting temperature
Standard
High
Low
Heating
capacity
Heating
capacity
With SW5-2 "ON"
Thermostat setting temperature
Note (1) Refer to page 911 for position of SW
(10) Value shift adjustment of room air temperature detection in heating
Under the standard specifications, the room temperature is adjusted at the setting temperature by controlling the indoor unit
capacity based on the setting temperature of thermostat and the suction air temperature.
However, where the unit is installed in the ceiling and warm air tends to stay around the ceiling, temperature in the living space
may not be adjusted at the setting temperature. In such occasion, it is recommended to change the setting of dip switch SW5-2,
which is found on the PCB of the indoor unit, to ON position so that the capacity control is tripped at +3 above the setting
temperature of thermostat and thus the heating feeling will improve.
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