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Protection Control
SiUS30-1301
56
Function and Control
6.2
Low Pressure Protection Control
This low pressure protection control protects compressors against the transient decrease of low pressure.
[In cooling]
Pe: Value detected by low pressure sensor for master unit
Note:
1 This frequency control is carried out in whole system.
[In heating or simultaneous cooling/heating]
(When the condensing unit heat exchanger is used as evaporator.)
Pe: Value detected by low pressure sensor for each condensing unit
Note:
1 This frequency control is carried out in each condensing unit.
Normal operation
Low pressure standby
Pe < 10.1 psi
Pe < 49.3 psi
Pe < 34.8 psi
Pe > 56.5 psi
Less than 3 times
within 60 minutes
Pe >
49.3 psi
Pe
< 34.8 psi
Compressor 52 Hz
Hot gas solenoid valve (Y1S)
ON
Hot gas solenoid valve (Y1S)
OFF
When occurring 4 times within 60 minutes,
the error code “
E4
” is displayed.
Normal control
Low pressure standby
Pe < 10.1 psi
Pe < 91.3 psi
Pe < 79.7 psi
Pe > 102.9 psi
Pe > 98.6
psi
Pe
< 91.3 psi
Compressor 52 Hz
Compressor upper limit down
1 step/10 seconds
Less than 3 times
within 60 minutes
Compressor upper limit up
1 step/20 seconds
When occurring 4 times within 60 minutes,
the error code “
E4
” is displayed.