Daikin VRV II RXYQ5MATL, Service Manual

Page: 98 / 331

Si39-504 Protection Control
Function 87
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]
In the case of multi-outdoor-unit system, the entire system performs this control in the
following sequence.
[In heating operation]
In the case of multi-outdoor-unit system, each outdoor unit performs this control
individually in the following sequence.
Low pressure not limited
Pe<0.34MPa
Low pressure standby
Low pressure limited
All STD compressors
stop.
Master unit:52 Hz + OFF + OFF
Slave unit:Stop
Pe<0.25MPa
Pe>0.39MPa
Pe<0.07MPa
Pe: LP pressure sensor detection
value for master unit
When occurring 4 times within 30 min.,
the malfunction code “ E4 ” is output.
Pe<0.17 MPa
Pe<0.13 MPa
Pe >0.23 MPa
INV upper limit frequency = 210 Hz
Pe<0.07 MPa
&
Low pressure not limited
Low pressure standby
Low pressure limited
INV upper limit frequency: 1-step /
20 sec up from current compressor
frequency
52 Hz + OFF + OFF
Pe: LP pressure sensor detection
value for each outdoor unit
Pe>0.20 MPa
Pe<0.17 MPa
When occurring 4 times within 30 min.,
the malfunction code “E4” is output.
INV upper limit frequency:
3-step down from current
compressor frequency