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Compressor Discharge Superheat Control (Expansion Valve <Lev4>); Evaporation Temperature Control (Expansion Valves <Lev5A>); Control At Initial Startup - Mitsubishi Electric PURY-HP72 Service Handbook

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[5-2 Outdoor Unit Control ]
Compressor discharge superheat control (expansion valve <LEV4>)
Compressor discharge superheat of OC and OS is controlled separately.
Compressor discharge superheat (calculated based on the compressor discharge temperature (TH4) and high pressure
(63HS)) is controlled by LEV4 every 30 seconds to stay within the certain target ranges that corresponds to given compressor
Compressor frequency
93 Hz or above
83 - 92Hz
72 - 82Hz
71 Hz or below
Evaporation Temperature Control (Expansion Valves <LEV5a>)
(1) LEV5 control will begin when all of the following conditions are met.
Units are operated in the Heating-Only or Heating-Main mode.
TH7<5°C [41°F]
63LS<0.69MPa [99psi]
TH15<4°C [39°F]
(2) LEV5 control will end when one or more of the following conditions are met.
Units are operated in the mode other than Heating-Main or Heating-Only.
TH7>10°C [50°F]
63LS>0.98MPa [142psi]
The LEV is controlled every 30 seconds to maintain constant the bypass inlet temperature of the BC controller during heat-
ingmain mode or heating mode. When LEV5 is being controlled, SV4a, b, and d will all be turned off.
The LEV operates at 300 pulse while the compressor is stopped. The LEV opens to a specified position in response to chang-
es in heat exchanger capacity control patterns during cooling only or cooling main mode.

Control at Initial Startup

When started up for the first time before 12 hours have elapsed after power on, the unit goes into the initial startup mode.
At the completion of the initial operation mode on the OC and OS, they will go into the normal control mode.
(1) Single-outdoor-unit system
Target compressor discharge superheat
20°C [36°F]
25°C [45°F]
30°C [54°F]
40°C [72°F]
Initial startup mode starts.
Completed in the integrated operation time of 35 minutes.
F < 50Hz
Completed in the integrated operation time of 90 minutes.
or the discharge superheat (TH4 - Tc) is detected (within
5 minutes of startup) that remains above approximately
25 degrees for one minute .
Initial startup mode complete
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