Alarm surveillance
During start the following alarms are delayed:
Low oil pressure 45 sec.
High filter diff. pressure 300 sec.
Low superheat 300 sec.
High superheat 300 sec.
Low/high oil temperature 300 sec.
3.3.6 SAB 128HR and 163HR with oil pump
The compressors SAB 128 HR and SAB 163 HR are frequency regulated screw compressors,
i.e. the capacity slide is fixed in maximum position and cannot be moved.
The electric oil pump is used for prelubrication and to maintain a minimum oil pressure during
operation.
The pump is started and stopped in accordance with the compressor differential pressure (dis-
charge pressure - suction pressure) during operation.
The difference is set in the picture Oil/Pressure/Control whereupon Set point 1 and Set point 2
will appear.
Normal setting for SAB 128/163 HR:
Set point 1 = 2.5 bar
Set point 2 = 4.0 bar
Adjust set points as described in subsection 3.3.5.
Starting sequence
Once the compressor has received permission to start, the oil pump starts and oil is pumped
into the compressor lubrication system.
The oil flow switch must be activated within 600 seconds to avoid shutdown.
When the oil flow switch is activated, the solenoid valve (capacity slide down) will be open for
15 seconds and the electric fan will start. The frequency converter will receive a signal to
start.
Speed is increased to 1000 rpm in 10 seconds.
The pump will operate for a minimum of 60 seconds and stop if the differential pressure is
higher than Set point 2 as described above.
Alarm surveillance
During start the following alarms are delayed:
See also section 6.5. Timers.
Low oil pressure 45 sec.
High filter diff. pressure 300 sec.
Low superheat 300 sec.
High superheat 300 sec.
Low/high oil temperature 300 sec.
Compressor control and surveillance
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Engineering manual - Unisab III 1.10
001930 en 2014.09
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