Protective Control Function - Mitsubishi SRK50ZHX-S Technical Manual

4.12 Protective control function

(1) Frost prevention control (During cooling or dehumidifying)
(a) Operating conditions
1) Indoor heat exchanger temperature (Th2) is lower than 5ºC.
2) 5 minutes after reaching the inverter command speed except 0 rps.
(b) Detail of anti-frost operation
Indoor heat exchanger
Item
Lower limit speed
Indoor fan
Outdoor fan
4-way valve
Notes (1) When the indoor heat exchanger temperature is in the range of 2.5~5 ºC, the speed is reduced by 4 rps at each 20 seconds.
(2) When the temperature is lower than 2.5 ºC, the compressor is stopped.
(3) When the indoor heat exchanger temperature is in the range of 5~8 ºC, the inverter command speed is been maintained.
(c) Reset conditions: When either of the following condition is satisfied.
1 The indoor heat exchanger temperature (Th2) is 8ºC or higher.
2 The inverter command speed is 0 rps.
(2) Cooling overload protective control
(a) Operating conditions: When the outdoor air temperature (Th5) is 41ºC or higher continues for 30 seconds while the
(b) Detail of operation
1) The outdoor fan is stepped up by 3 speed step. (Upper limit 8th speed.)
2) The lower limit of inverter command speed is set to 30 rps and even if the calculated result becomes lower than that after
fuzzy calculation, the speed is kept to 30 rps. However, when the thermo becomes OFF, the speed is reduced to 0 rps.
(c) Reset conditions: When either of the following condition is satisfied.
1 The outdoor air temperature is lower than 40ºC.
2 The inverter command speed is 0 rps.
(3) Cooling high pressure control
(a) Purpose: Prevents anomalous high pressure operation during cooling.
(b) Detector: Outdoor heat exchanger sensor (Th4)
(c) Detail of operation:
(Example) Fuzzy
Notes (1) When the outdoor heat exchanger temperature is in the range of 58~63 ºC, the speed is reduced by 6 rps at each 30 seconds.
(2) When the temperature is 63 ºC or higher, the compressor is stopped.
(3) When the outdoor heat exchanger temperature is in the range of 53~58 ºC, if the inverter command speed is been maintained and the operation has
continued for more than 30 seconds at the same speed, it returns to the normal cooling operation.
temperature
5°C or lower
25 rps
Depends on operation mode
Depends on operation mode
OFF
inverter command speed of other than 0 rps.
After lapse of 30 sec. or over
After lapse of 30 sec. or over
After lapse of 30 sec. or over
53
Outdoor unit heat exchanger temperature (˚C)
2.5°C or lower
0rps
Protects the fan tap just before
frost prevention control
Depends on stop mode
(3) (1)
6rps
(3)
6rps
lower limit
(3)
speed 30 rps
58
15
- -
Inverter
command
speed
Lower
limit
speed
0 rps
2.5
Indoor heat exchanger
temperature (°C)
(1)
0rps
63
5 8