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5 Protection Control
5.1 High Pressure Protection Control
This control protects the system from abnormally high pressure and protects the compressors from transient spikes in
pressure.
Figure 3-5.1: High pressure protection control
Notes:
1. P
c
: Discharge pressure
5.2 Low Pressure Protection Control
This control protects the system from abnormally low pressure and protects the compressors from transient drops in
pressure.
Figure 3-5.2: Low pressure protection control
1. P
e
: Suction pressure
5.3 Discharge Temperature Protection Control
This control protects the compressors from abnormally high temperatures and transient spikes in temperature. It is
performed for each compressor.
Figure 3-5.3: Discharge temperature protection control
When the discharge temperature rises above 120°C the system displays P4 protection and all units stop running. When P4
protection occurs 3 times in 100 minutes, the H6 error is displayed. When an H6 error occurs, a manual system restart is
required before the system can resume operation.
c
P
c
< 4.0MPa
Normal operation
High pressure protection, error code P1 is displayed
P
e
< 0.05MPa
e
Low pressure protection, error code P2 is displayed
When P2 protection occurs 3 times
in 60 minutes, the H5 error is
displayed. When an H5 error occurs,
a manual system restart is required
before the system can resume
operation.
o
o
Discharge temperature
o
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