Mitsubishi Electric 500YEMK-A, Руководство по обслуживанию

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(5) Oil return control (Electronic expansion valve (SLEV))
• The amount of opening of the oil-return LEV (SLEV) is determined as follows: in cooling, by the operating
of the No. 1 compressor and the ambient temperature; in heating, by the operating capacity of the
• It is opened (64) when both compressors are stopped and started for 10 minutes. (Upper limit of LEV opening
= 388 pulse.)
• SLEV = 0 when the No. 1 compressor is stopped.
capacity
(6) Sub-cool coil control (Electronic expansion valve (LEV1))
• The sub-cool coil control provides control every 30 seconds to keep the super heat volume from the temperature
the inlet/outlet of the sub-cool coil (TH8, TH9) within a stable range (2 to 4 degrees).
• It controls by correcting the amount of opening according to the temperature of the inlet/outlet of the sub-cool
(TH5, TH7), the high pressure (Pd) and discharge temperature.
• It is closed (0) in heating or when the compressor is stopped.
• It has a fixed opening (480) in defrosting.
• During normal control, the operating range is 46 to 480.
(7) Defrosting control
1) Start of defrosting
• After there has been heating operation for 50 minutes or after 90 minutes has passed and a piping temperature
(TH5) of 0˚C or less is detected for a preset time, defrosting begins.
• When 10 minutes has passed since the compressor began operation or if 10 minutes has passed since recovery
from defrosting, setting the forced defrosting switch (Dip SW2-7) to starts forced defrosting.
2) End of defrosting
• Defrosting ends when 15 minutes has passed since the start of defrosting or when the piping temperature (TH5)
becomes 7˚C or more. (Note that if defrost-prohibited time has been set to 90 minutes, the defrost-prohibit time will
be 50 minutes following a 15 minute timed recovery.)
• Ending the defrosting is prohibited for 2 minutes after the start of defrosting. (Note that the defrosting operation will
be ended if the piping temperature exceeds 20˚C within 2 minutes of the start of defrosting.
3) Defrost-prohibit
• Defrosting is not performed for 10 minutes after the start of compressor operation and during oil recovery mode.
4) Abnormalities during defrosting
• If an error is detected during defrosting, the defrosting is stopped and the defrost-prohibit time is set to 20 minutes
by the compressor cumulative operating time
No. 1 compressor.
is So
of
coil