Low Pressure Protection Control - Daikin VRV III RXYQ5-54PY1 Service Manual

Si34-601A
4.2

Low Pressure Protection Control

This low pressure protection control is used to protect compressors against the transient
decrease of low pressure.
[In cooling operation]
★
Low pressure not limited
Pe<0.34MPa
Low pressure limited
All STD compressors
Pe<0.25MPa
Master unit:52 Hz + OFF + OFF
Slave unit:Stop
Pe<0.07MPa
Low pressure standby
[In heating operation]
★
Low pressure not limited
Pe<0.17 MPa
INV upper limit frequency:
3-step down from current
compressor frequency
Pe<0.17 MPa
Pe<0.13 MPa
52 Hz + OFF + OFF
Function
In the case of multi-outdoor-unit system, the entire system performs this control in the
following sequence.
Pe>0.39MPa
stop.
In the case of multi-outdoor-unit system, each outdoor unit performs this control
individually in the following sequence.
Pe >0.23 MPa
&
INV upper limit Hz = MAX
After 10 sec.
Low pressure limited
After 10 sec.
Pe<0.07 MPa
Low pressure standby
Pe: LP pressure sensor detection
Pe<0.15MPa
When occurring 4 times within 30 min.,
the malfunction code " E4 " is output.
Pe: LP pressure sensor detection
value for each outdoor unit
Pe >0.20 MPa
INV upper limit frequency: 1-step
up from current compressor
frequency
After 15 sec.
When occurring 4 times within 30 min.,
the malfunction code "E4" is output.
Protection Control
value for master unit
Hot gas SVP = OFF
Pe>0.30MPa
Hot gas SVP = ON
Hot gas SVP = OFF
Pe<0.12MPa
Hot gas SVP = ON
Pe>0.17MPa
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