Mitsubishi Heavy Industries MHI FDU71VNXVF1 Technical Manual page 271

(h) Power transistor temperature protection
(i) Protective control
If the power transistor temperature (detected with TIP) exceeds the setting value, the compressor speed (frequency)
is controlled to suppress the rise of power transistor temperature.
Reset
81(77)
Power transistor temp. (°C)
(i) Anomalous power transistor current
(i) Prevents over-current on the inverter. If the current value in the power transistor exceeds the setting value, the
compressor stops.
(ii) If the current value in the power transistor exceeds the specified value and the compressor stops 4 times within 30
minutes, E42 is displayed on the remote control and it enters the anomalous stop mode.
(j) Anomalous inverter PCB
If the power transistor detects any anomaly for 15 minutes, including the stop of compressor, E51 is displayed on the
remote control and it enters the anomalous stop mode.
(k) Anti-frost control by the compressor frequency control
(i) If the indoor unit heat exchanger temperature (detected with Th
start of compressor, the compressor speed (frequency) is controlled to initiate the anti-frost control of indoor unit
heat exchanger.
(ii) When there are 3 indoor unit heat exchanger temperatures (Th
Reduces compressor frequency
at each minute.
(iii) Regarding the anti-frost control by the operation stop, refer to the operation control function by the indoor unit
controller and the cooling, dehumidifying frost prevention of page 255.
(l) Dewing prevention control
[Control condition] During cooling and dehumidifying operation, if all the following conditions are established, the
compressor speed (frequency) is reduced to prevent dewing and water splash.
➀ Cooling electronic expansion valve aperture (EEVC) is 500 pulses.
➁ Suction overheat is 10°C or higher.
③ Compressor speed (frequency) is 60 rps or higher.
[Control contents] ➀ When the suction overheat is 10°C or higher, the compressor speed (frequency) is reduced at each
➁ Compressor speed (frequency) does not rise till the cooling expansion valve becomes 460 pulses.
③ This control takes 60 rps as its lower limit so that compressor speed is not controlled when it is
(m) Refrigerant quantity shortage protection
Under the compressor protection start III control during cooling and dehumidifying operations, the following control is
performed by detecting the indoor unit heat exchanger temperature (Th
(Th -A).
I
[Control condition]
[Control contents]
Reduces compressor frequency
at each minute.
Retention
85(80)
Retention
1.5 3.5
Indoor unit heat exchanger temp. (°C)
1 minute.
less than 60 rps.
When the state that the indoor unit heat exchanger temperature (Th
the indoor unit return air temperature (Th
It judges that the flowing of refrigerant in to the indoor unit is insufficient so that the compressor is
stopped and E57 is displayed on the remote control.
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Note (1) Value in ( ) are for the single phase 100~140 model.
-R) exceeds the setting value at 4 minutes after the
I
-R), the lowest temperature is detected.
I
Reset
-R) and the indoor unit return air temperature
I
-A) by 4°C or more continues for 1 minute.
I
270
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'12 • PAC-T-178
-R) does not become lower than
I