SiAF341904E
Protection Control
Part 4 Functions and Control
87
6. Protection Control
6.1 High Pressure Protection Control
This high pressure protection control is used to prevent the activation of protection devices due
to abnormal increase of high pressure and to protect compressors against the transient
increase of high pressure.
Cooling
The following control is performed in the entire system.
6.2 Low Pressure Protection Control
This low pressure protection control is used to protect compressors against the transient
decrease of low pressure.
Cooling
Because of common low pressure, the following control is performed in the system.
Normal operation
Pc > 3.55 MPa
High pressure standby
Reduce compressor capacity step
Pc > 3.72 MPa
Pc < 3.04 MPa
When occurring 3 times within 40
minutes, high pressure switch is
activated without high pressure standby,
thus outputting the error code
E3
.
Pc: High pressure sensor detection
value for each outdoor unit.
Normal operation
Pe < 0.35 MPa
Low pressure standby
Reduce compressor capacity step
Pe < 0.07 MPa
Pe > 0.40 MPa
When occurring 3 times within 60
minutes, the error code
E4
is output.
Pe: Low pressure sensor detection
value for master unit.
