Mitsubishi Electric CITY MULTI PUHY-400YMF-C, 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 capacity
of the No. 1 compressor and the ambient temperature; in heating, by the operating capacity of the No. 1 compressor.
• It is opened (64pulses) when both compressors are stopped and started for 10 minutes. (Upper limit of LEV opening
is So = 388 pulse.)
• SLEV = 0 when the No. 1 compressor is stopped.
(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 – 8 C or less is detected for a preset time, defrosting begins.
• When 10 minutes has passed since the compressor began operation or for forced defrosting (Setting of Dip SW2-
7 on) when 10 minutes has passed since recovery from defrosting forced defrost mode recomes active.
2) End of defrosting
• Defrosting ends when 12 minutes have passed since the start of defrosting, or when a piping temperature (TH5 and
TH7) of 7 C or more is detected for 4 minutes or longer. (Note that if the defrost-prohibited time is set on 90 minutes,
the defrost-prohibit time will be 50 minutes following a 12-minute timed recovery.
• Ending the defrosting is prohibited for 4 minutes after 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
(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 of
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 coil
(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.
5) Change in number of operating indoor units while defrosting
• If the number of indoor units changes while the outdoor unit is defrosting, the defrosting operation continues. Once
defrosting has ended, control for changing the number of units is performed.
• If the indoor unit is stopped while the outdoor unit is defrosting or if the thermostat is set to off, the defrosting
operation continues. Once defrosting has ended, the unit is stopped.
6) Number of compressors operating during defrosting
• The number of compressors operating during defrosting is always two.
(8) Control of liquid level detecting heater
Detect refrigerant liquid level in accumulator, and heat refrigerant with liquid level heater for judging refrigerant amount.
7 steps of duty control is applied to liquid level heater depending on frequency and outdoor air temperature, 1 minute
after starting compressor.