Daikin R407C PLUS, Service Manual

Page: 85 / 267

Outline of Control (Outdoor Unit) < Symbols using in this manual > Si33-105
74 Function R407C PLUS Series Heat Recovery System
3.5.2 Low Pressure Protection Control
The following control is provided to protect the compressors from abnormal decrease of low
pressure (LP).
"
1.Upper limit compressor operation : According to “Drooping step Table”. See next page.
Normal operation
Normal operation
H
SVP : OFF
E4 malfunction
stop
Forced thermostat
OFF
LP<0.15MPa
LP<0.05MPa
LP>0.10MPa
LP<0.03MPa LP<0.0MPa
Compressor
operation
frequency
31Hz+OFF+OFF
LP<0.05MPa
SVP (for hot gas
bypass) : ON
LP<0.08MPa
SVP (for hot gas
bypass) : OFF SVP (for hot gas
bypass) : ON
OR
•
&
•
Ta<Tes+5
•
LP>0.20MPa
•
30 sec elapse
OR
•
&
•
&
•
LP>0.13MPa
•
Ta>5˚C
•
LP<0.098MPa
•
Ta
≤
5˚C
OR
•
&
•
&
•
LP<0.08MPa
•
Ta>5˚C
•
LP<0.049MPa
•
Ta
≤
5˚C
H
Malfunction reset
LP>0.09MPa
LP>0.10MPa
(Monitoring LP every 30 sec.)
LP>0.07MPa
(Monitoring LP every 1 min)
Ta : Outdoor air temp. (˚C)
Tes : Low pressure equivalent
saturation temp. (˚C)
[Heating mode]
[Cooling mode]
SVP (for hot
gas bypass) : ON
LP > 0.13 MPa
Upper limit frequency =
Maximum frequency
1-step increase for
compressor
operation frequency
[Oil return mode (common for cooling / heating)]
Restriction for upper limit
compressor operation
frequency
H
1
(V0822)