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43
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'12 • SRK-T-126
(g) Heating low outdoor temperature protective control
1) Operating conditions:
When the outdoor air temperature (TH2) is lower than -10ºC or higher continues for 30 sec-
onds while the compressor command speed is other than 0 rps.
2) Detail of operation:
The lower limit compressor command speed is change as shown in the figure below.
-10
-7
Lower limit 45 rps
Normal operation
Outdoor air temperature (°C)
3) Reset conditions:
When either of the following condition is satisfied.
a) The outdoor air temperature (TH2) becomes -7ºC.
b) The compressor command speed is 0 rps.
(h) Compressor overheat protection
1) Purpose:
It is designed to prevent deterioration of oil, burnout of motor coil and other trouble resulting from the
compressor overheat.
2) Detail of operation
a)
Speeds are controlled with temperature detected by the sensor mounted on the discharge pipe.
Discharge pipe temperature (˚C)
Lower limit
(4)
After lapse of 3 min. or over
(3)
After lapse of 3 min. or over
(3)
After lapse of 3 min. or over
(3)
4 rps
4 rps
(1)
0 rps
100
110
(Example) Fuzzy
90
Notes (1) When the discharge pipe temperature is in the range of 100~110ºC, the speed is reduced by 4 rps.
(2) When the discharge pipe temperature is raised and continues operation for 20 seconds without changing, then the speed is reduced again by 4 rps.
(3) If the discharge pipe temperature is in the range of 90~100ºC even when the compressor command speed is maintained for 3 minutes when the
temperature is in the range of 90~100ºC, the speed is raised by 1 rps and kept at that speed for 3 minutes. This process is repeated until the
command speed is reached.
(4) Lower limit speed
Cooling
Heating
Lower limit speed
20 rps
30 rps
Item
Model
b)
If the temperature of 110ºC is detected by the sensor on the discharge pipe, then the compressor will stop immediately.
When the discharge pipe temperature drops and the time delay of 3 minutes is over, the unit starts again within 1
hour but there is no start at the third time.
(i)
Current safe
1) Purpose:
Current is controlled not to exceed the upper limit of the setting operation current.
2) Detail of operation:
Input current to the converter is monitored with the current sensor fixed on the printed circuit
board of the outdoor unit and, if the operation current value reaches the limiting current value, the
compressor command speed is reduced.
If the mechanism is actuated when the compressor command speed is less than 30 rps, the compressor
is stopped immediately. Operation starts again after a delay time of 3 minutes.
(j)
Current cut
1) Purpose:
Inverter is protected from overcurrent.
2) Detail of operation:
Output current from the inverter is monitored with a shunt resistor and, if the current exceeds the
setting value, the compressor is stopped immediately. Operation starts again after a delay time of
3 minutes.
