Daikin FTXC50A - 2.19 High Pressure Protection; 2.20 Discharge Pipe Temperature Control

Algorithm & Control
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2.19 High Pressure Protection
To prevent high pressure in the system.
Compressor operating frequency is adjusted based on upper limit of coil temperature.
Upper Limit Coil
Temperature
Compressor frequency
A
64°C
B C
The compressor frequency is adjusted based on coil temperature:
• During cooling mode : outdoor coil temperature.
• During heating mode : indoor coil temperature.
Thisprotectionisactivatedwhenthecoiltemperature>64°C,thecompressorstopsandoutdoorfanstops
after 30s.The unit can only be restarted after 3 minutes.
2.20 Discharge Pipe Temperature Control
Used as a measure of the compressor’s internal temperature.
Compressor frequency is control to keep this temperature from going up further when it rises above a certain
level.
Discharge temperature
Stop zone
Drop zone
Frequency
keep zone
Reset zone
110°C
102°C
99°C
90°C
Ifcompressordischargetemperature>102°Cforthersttime,thiscontrolstartsandsetsthecurrent
frequency as upper limit. At the same time, running frequency starts to reduce by 1 step and so on, until
temperaturefallsbetween99°Cand90°Catthekeepzone.
Thisprotectionisactivatedwhenthecompressordischargetemperature>110°C.Thecompressorwillstop
and considered trip.
Ifthecompressordischargetemperature<90°C,thecompressorfrequencywillberesetbasedonthe
outdoor ambient, set and room temperature.