Max. required level
Max. required level
3. Compressor Control
2WAY VRF SYSTEM
Control Functions
* Discharge temperature that is used for this control is the highest temperature among all compressors.
When the temperature falls in the Area D (over PX temperature), the operation stops within 0 to
30 seconds at the interval of the roadmap control.
After Tc falls in the Area D and the thermostat is turned OFF, the system may resume operating
from the lower compressor capacity.
Test Run
Test run mode in heating operation is used when the room temperature is high and the indoor unit
thermostat is not turned ON. This mode is used for operation check when the outdoor unit is fully
operated or additional refrigerant charge without stopping the system.
When the system operates in a minimum capacity, the system will continue operating for at least
6 minutes if the condensation temperature area is the Area C.
If it maintains in the Area C, the thermostat may turn OFF.
Once the indoor unit is selected for the test run, the thermostat will not be turned OFF.
However, condensation temperature control is performed in order to prevent the high load
according to the figure shown on previous page.
After the last indoor unit is operated in the test run mode, the test run is automatically cancelled
after 1 hour.
4-3. Protection Control
Compressor stops
Horsepower decreases
Horsepower cannot increase
Horsepower can increase
Capacity goes down 2.0HP
Capacity goes down 1.0HP
Capacity goes down 0.5HP
Compressor discharge temperature protection
The compressor capacity is controlled according to the figure below.
1
Low pressure protection control
In order to prevent the excessive decrease of low pressure, the compressor capacity is controlled
according to the figure below.
2
106
105
104
100
Capacity goes down 0.3HP
96
94
°C
No restriction
Capacity goes up slowly
0.25
0.20
Capacity cannot increase
Capacity goes down
H06 trip (Continuous for 2 minutes)
0.17
0.06
H06 trip0.02
Low pressure
MPa
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