Midea M-thermal Mono Series - Page 25

M thermal Mono
202004 23
Part 3 - Control
5.5 Voltage Protection Control
This control protects the M thermal Mono from abnormally high or abnormally low voltages.
Figure 3-5.4: Compressor voltage protection control
When the phase voltage of AC power supply is at or above 265V for more than 30 seconds, the system displays H7
protection and the unit stops running. When the phase voltage drops below 265V for more than 30 seconds, the
refrigerant system restarts once the compressor re-start delay has elapsed. When the phase voltage is at or below 172V,
the system displays H7 protection and the unit stops running. When the AC voltage rises to at or more than 187V, the
refrigerant system restarts once the compressor re-start delay has elapsed.
5.6 DC Fan Motor Protection Control
This control protects the DC fan motors from strong winds and abnormal power supply. DC fan motor protection occurs
when any one of the following three sets of conditions are met:
 Outdoor ambient temperature is at or above 4°C and actual fan speed differs from target fan speed by more than
200rpm for more than 3 minutes.
 Outdoor ambient temperature is below 4°C and actual fan speed differs from target fan speed by more than 300rpm
for more than 3 minutes.
 Actual fan speed is less than 150rpm for more than 90 seconds.
When DC fan motor protection control occurs the system displays the H6 error code and the unit stops running. After 3
minutes, the unit restarts automatically. When H6 protection occurs 10 times in 120 minutes, the HH error is displayed.
When an HH error occurs, a manual system restart is required before the system can resume operation.
5.7 Water Side Heat Exchanger Anti-freeze Protection Control
This control protects the water side heat exchanger from ice formation. The water side heat exchanger electric heater is
controlled according to outdoor ambient temperature, water side heat exchanger water inlet temperature and water side
heat exchanger water outlet temperature.
In heating mode, if the outdoor temperature falls below 3°C and either the water side heat exchanger water inlet
temperature or water side heat exchanger water outlet temperature are below 25°C, the water side heat exchanger
electric heater turns on. When the outdoor ambient temperature rises above 5°C and either the water side heat exchanger
water inlet temperature or water side heat exchanger water outlet temperature are above 30°C, the water side heat
exchanger turns off.
When water side heat exchanger anti-freeze protection occurs the system displays error code Pb and the unit stops
running.
Voltage ≥ 265V
or Voltage ≤ 172V
254V < Voltage < 187V
Normal operation
Compressor voltage protection, error code H7 is
displayed
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