Daikin VRV R-407C PLUS Series, Service Manual

Page: 72 / 193

SiE 00-07 Outline of Control (Outdoor Unit)
Function R-407C PLUS Series 61
3.13 Discharge Pipe Temperature Control
Controls the liquid injection and operating frequency to prevent abnormal increase of discharge pipe
temperature and compressor internal temperature.
3.13.1 Liquid Injection Control
Inverter compressor
Opens SVTi (Y3S) (solenoid valve for inverter compressor liquid injection) for 3 minutes after
software startup.
[Cooling]
DSHi: Inverter compressor discharge pipe superheated degree
= Tdi (Th3-1) - (HP equivalent saturation temperature)
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]
SVTi (Y3S) is OFF at any case when inverter compressor stops.
STD compressor
[In cooling operation]
DSHs: STD compressor discharge pipe superheated degree
= Tds1, 2 (Th3-2) - (HP equivalent saturation temperature)
Tds1, 2 : STD compressor discharge pipe temperature (Th3-2)
Normal operation SVTi : ON
DSHi
≥
40˚C
DSHi<15˚C
(V0826)
OR
&
DSHi<25˚C
10min elapsed
Normal operation SVTi : ON
•
Tdi
≥
100˚C
•
LP<0.05MPa
•
(HP+0.10) / (LP+0.10)>8
•
Tdi<90˚C
•
LP>0.07MPa
•
2 min elapsed
(V0827)
OR
&
Preparing oil return
and defrosting
SVTi : ON
DSHi
≥
15˚C
Start oil return
& Defrost operation
(V0828)
Normal operation
SVTs1 (Y4S), SVTs2 (Y6S) : ON
10 min
DSHs1, DSHs2
≥
40˚C
DSHs1, DSHs2<15˚C
(V0829)