Daikin R407C PLUS Service Manual page 88

Si33-105
3.5.3 Discharge Pipe Temperature Control
Controls the liquid injection and operating frequency to prevent abnormal increase of discharge
pipe temperature and compressor internal temperature.
Liquid Injection Control
Inverter compressor
!
[Cooling and Simultaneous cooling / heating operation]
DSHi: Inverter compressor discharge pipe superheated degree
Tdi: Inverter compressor discharge pipe temperature (Th3-1)
[Heating]
[Preparing Oil return and defrosting operation (1 min before operation start)]
!
[Oil return operation/defrosting operation]
!
Function R407C PLUS Series Heat Recovery System
Opens SVTi (Y3S) (solenoid valve for inverter compressor liquid injection) for 3
minutes after software startup.
Normal operation
= Tdi (Th3-1) - (HP equivalent saturation temperature)
Normal operation
Preparing oil return
and defrosting
SVTi is ON during oil return and defrost operation.
SVTi (Y3S) is OFF at any case when inverter compressor stops.
Outline of Control (Outdoor Unit) < Symbols using in this manual >
DSHi>15˚C
&
DSHi≥40˚C
OR
Lp<0MPa
DSHi<15˚C
DSHi<25˚C
OR
& Lp>0MPa
10min elapsed
• Tdi≥100˚C
• LP<0.05MPa
OR
• (HP+0.10) / (LP+0.10) >8
&
• DSHi>35˚C
• Tdi<90˚C
• LP>0.07MPa
&
• 2 min elapsed
OR
• DSHi<20˚C
DSHi≥15˚C
SVTi : ON
(V0826)
SVTi : ON
(V0827)
Start oil return
SVTi : ON
& Defrost operation
(V0828)
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