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28˚C (82.4°F) or more
111 111 157
20 ~ 30˚C (68~86°F)
87 87 134
22˚C (71.6°F) or less
64 64 87
3 Back up of frequency control by bypass valve
During 20Hz operations, frequency is backed up by turning on (opening) bypass valve (SV2).
• Cooling
During 20Hz operations 3 minutes after starting compressor, bypass valve is
turned on when ET is -30˚C (-22°F) or less, and turned off when ET is -15˚C
(5°F) or more.
• Heating
During 20Hz operations 3 minutes after starting compressor, SV2 turned on
when high pressure (Pd) exceeds pressure limit (See previous page.), and
turned off when Pd falls to 20kg/cm
2
G or less.
(5) Oil return control (Electronic expansion valve <SLEV>)
Oil return LEV (SLEV) opening is dependent on frequency and outdoor air tem-
perature.
SLEV is closed (0) when compressor stops, and SLEV is set (64) for 10 minutes after starting compressor
.
Operation mode
Cooling (Dry)
Operation mode
Heating
Frequency
Outdoor air temp.
20 ~ 74Hz 75 ~96Hz 97Hz or more
Note :1. Differential of outdoor air temperature is 2 degrees.
2. The opening shown above may be expanded for preventing rise in discharge temperature (at Td
>
=
90˚C).
(Number of pulse)
Frequency
Outdoor air temp.
20 ~ 74Hz
75 ~96Hz 97Hz or more
– 87 87 111
ON
OFF
ON
OFF
-30˚C
(-22°F)
(284psi) (313psi)
(5°F)
-15˚C
20kg/cm
2
G 22kg/cm
2
G
(6) Subcool coil control (electronic expansion valve <LEV1>)
• The amount of super heat detected from the bypass outlet temperature of subcool coil (TH8) is controlled to be
within a certain range for each 20 sec.
• The opening angle is corrected and controlled depending on the outlet/inlet temperature of subcool coil (TH5, TH7)
and the discharge temperature.
• However, the valve will be closed (0) at heating and compressor stopping.
• It will fully open at defrosting.
(7) Defrost operation control
1) Starting of defrost operations
• After integrated 50 minutes of compressor operations, defrosting operations start when –2˚C (28.4°F) or less of
piping temperature (TH5) is detected for 10 consecutive minutes.
• Forcible defrosting operations start by turning on forcible defrost switch (SW2-7) if 10 minutes have already elapsed
after compressor start or completion of defrosting operations.
2) Completion of defrosting operations
Defrosting operations stop when 10 minutes have passed since start of defrosting operation, or piping temperature
(TH5) reaches 12˚C (53.6°F) (80TMU), 8˚C (46.4°F) (100TMU) or more.
(Defrosting operations do not stop for 2 minutes after starting, except when piping temperature exceeds 20˚C.)
3) Defrosting prohibition
Defrosting operations do not start during oil recovery, and for 10 minutes after starting compressor.
4) Trouble during defrosting operations
When trouble is detected during defrosting operations, the defrosting operations stop, and defrosting prohibition time
decided by integrated operation time of compressor is set to be 20 minutes.
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