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36
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'10 • SRK-T-100
(f) Compressor overheat protection
1) Purpose:
It is designed to prevent deterioration of oil, burnout of motor coil and other trouble resulting from the com-
pressor overheat.
2) Detail of operation
a)
Speeds are controlled with temperature detected by the sensor mounted on the discharge pipe.
(Example) Fuzzy
Notes (1) When the discharge pipe temperature is in the range of 100 to 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 still 90ºC or greater but less than 100ºC even when the compressor command speed is maintained for 3 minutes
when the temperature is 90ºC or greater but less than 100ºC, the speed is raised by 2 rps and kept at that speed for 3 minutes. This process is
repeated until the compressor command speed is reached.
(4) Lower limit speed
Cooling
Heating
Models 25, 35
20 rps
30 rps
Model 50
24 rps
29 rps
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.
(g) 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 speed of compressor command is less than 30 rps, the
compressor is stopped immediately. Operation starts again after a delay time of 3 minutes.
(h) Current cut
1) Purpose:
Inverter is protected from overcurrent.
2) Detail of operation:
Output current from the converter 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.
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
90
100
110
(ii) Protective control
II
1) Operating conditions:
When the outdoor air temperature sensor (TH2) is 0ºC or lower continuously for 30 seconds while
the compressor command speed is other than 0 rps.
2) Detail of operation:
The outdoor fan motor speed is stepped up by 2 speed step. (Upper limit 7th speed)
3) Reset conditions:
When the either of the following condition is satisfied.
a) When the outdoor air temperature sensor (TH2) becomes 2ºC or higher.
b) When the compressor command speed is 0 rps.
