Low Pressure Protection Control - Daikin FCQ18PVJU Service Manual

SiUS28-902_a
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]
Pe < 36 psi
Low pressure
limited
Pe
[In heating operation]
• Pe>36 psi
& • INV. upper limit
frequency
Low pressure limited
Pe>28 psi (every 20 sec.)
SVP = OFF
Function
Low pressure not limited
Pe > 57 psi
57Hz
< 10 psi
Low pressure
standby
Low pressure not limited
Pe<23 psi
Upper limit:
145.5Hz
Pe<19 psi
Upper limit:
57Hz
Pe>28 psi
Upper limit: 1-step up from
current compressor frequency
Pe>25 psi
Pe<15 psi
Pe
Low pressure
standby
Pe: LP pressure sensor detection
value
When occurring 3 times within 60 min.,
the malfunction code "
Pe: LP pressure sensor detection
More than 145.5Hz
&
Pe<23 psi
Pe<19 psi
SVP = ON
<10 psi
When occurring 3 times within 60 min.,
the malfunction code "
Protection Control
E4
"
is output.
value
E4
"
is output.
30