Mitsubishi Heavy Industries FDTC40ZHXV Technical Manual page 170

(c) Protective control function
1) Frost prevention control (During cooling or dehumidifying)
a) Operating conditions
i) Indoor heat exchanger temperature (Th2) is lower than 5ºC.
ii) 5 minutes after reaching the inverter command speed except 0 rps.
b) Detail of anti-frost operation
Indoor heat exchanger
temperature
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 continues for 1 minute, the compressor is stopped.
(3) When the indoor heat exchanger temperature is in the range of 5~8 ºC, if the inverter command speed is been maintained and the
operation has continued for more than 20 seconds at the same speed, it returns to the normal cooling operation.
c) Reset conditions: When either of the following condition is satisfied.
1 When the signal to lower the hertz is received from the indoor unit.
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
b) Detail of operation
i) The outdoor fan is stepped up by 3 speed step. (Upper limit 8th speed.)
ii) 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 4 rps at each 30 seconds.
(2) When the temperature is 63 ºC or higher continues for 1 minute, 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.
(4) When the outdoor heat exchanger temperature in less than 53˚C, it returns to the normal heating operation.
5°C or lower 2.5°C or lower
25 rps
Protects the fan tap just before
Depends on operation mode
frost prevention control
Depends on operation mode
Depends on stop mode
OFF
the 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)
163
- -
Inverter
command
speed
Lower
limit
speed
0 rps
0rps
(1)
(3)
6rps
(3)
6rps
lower limit
(3)
speed 30 rps
58
2.5 5 8
Indoor heat exchanger
temperature (°C)
(1)
0rps
63