Johnson Controls SABROE Unisab III Control, Engineering Manual

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Engineering manual - UniSAB III 1.10.8
106/346
001930 en 2021.06
Compressor control and surveillance
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.
See also section 6.5 Timers .
3.3.10 FV 19 with oil pump
The compressor FV 19 is a small frequency-regulated screw compressor without the stage regulated ca-
pacity control as featured in SV 19.
The electrical oil pump is used for prelubrication and to maintain a minimum oil pressure during opera-
tion. 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 FV 19:
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 starting permission, the oil pump will start pumping oil into the com-
pressor lubrication system.
The oil flow switch must be activated within 45 seconds to avoid shutdown.
When the oil flow switch is activated, an oil by-pass solenoid valve for unloading will open for 15 sec-
onds and the electrical fan will start.
Starting signal is transmitted to the frequency converter.
The speed is increased to 1200 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:
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.
See also section 6.5 Timers .