Low Pressure Protection Control Step; Low Pressure Protection Control - Daikin VRV Inverter K Series Manual

SI-05C.BOOK Page 234 Monday, November 6, 2000 4:13 PM
Outline of Control
4.8

Low Pressure Protection Control Step

The following types of control are executed if low pressure drops below the reference values in order to
prevent temperature inside the compressor from rising abnormally due to drop of compressor suction
pressure, and in order to maintain oil pressure for supplying oil to the inside of the compressors during
operation.

Low Pressure Protection Control

3 times within Up to 2 times within
30 min 30 min
Lp < 0.0 Lp < 0.0
Stop due to E4 Forced OFF by
malfunction thermostat
Cancel Cancel
conditions conditions
Lp ≥ 0.9
Lp > 0.8
BL2K (60 + OFF) + (ON + OFF)
BL3K (60 + OFF) + (ON + OFF) + (ON + OFF)
Control During LPS
Operation of STD
Outdoor Unit
234
When cooling
During oil return /
defrost only
During oil return only
(Both cooling and
(Both cooling and
heating)
heating)
Lp < 0.2 Lp < 0.3
Compressor upper
All hot gas bypass
limit frequency
in same system ON
limited
Cancel
Cancel
conditions
conditions
Lp > 0.8
Oil return /
defrost
complete
Compressor frequency
1 step down
All hot gas bypass in
same system ON
However
system > Te + 10˚C, or
low pressure > 1.2k and
Cancel conditions
LP > 2.5k, or LP > 1.2k and all
oil temp. in same system > Te +
10˚C, and step down canceled
LP > 3k and hot gas OFF
3rd time within
30 min.
LPS operating
Stop due to E4
malfunction
Cancel conditions
Operation OFF
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INV outdoor unit only
Lp < 1.2
Lp < 1.0
DSH > 15
30Hz + OFF
Injection ON
Hot gas ON
Cancel
Cancel
conditions
conditions
Pe > 1.5
Pe > 1.8
OR
DSH < 10
When heating
Lp < 0.5 Lp < 0.8
Lower limit inverter
frequency limited to 54 Hz
Cancel
conditions
Lp >1.1
LP > 0.8 and all
oil temp. in same
1 step up
Up to 2 times within
30 min
LPS operating
Forced OFF by
thermostat
(VF115)
Functions PLUS Series
SiE-05C
No more than 3
min. following
completion of oil
return / defrost
LP < 2.5
All hot gas
bypass ON
Cancel
conditions
3 min. elapse
following
completion of
oil return /
defrost
(VF114)