Service manual

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