Sab 283 Mk1, Sab 330 And Sab 355 Mk1 With Oil Pump - Johnson Controls SABROE Unisab III Control Engineering Manual

Alarm surveillance
During start the following alarms are delayed:
Low oil pressure
High filter diff. pressure
Low superheat
High superheat
Low/high oil temperature 300 sec.
The delayed alarms are described in section 6.5. Timers.
Stopping sequence
When GST compressor stops, Unisab III will attempt to move the capacity slide below 5% po-
sition. The solenoid valve for decreasing capacity slide position is activated for maximum 300
seconds. If the capacity slide is not below 5% within the 300 seconds a Capacity error shut-
down will be issued.
Vi ratio regulation
Unisab III regulates the Vi ratio in three steps according to the actual pressure ratio. Before
switching from one Vi-step to another, the actual Vi ratio for the compressor must have been
present for at least the time indicated in timer 34 Vi-pause (60 seconds). Otherwise the
change of the Vi step will be cancelled.
Volume ratio 2.2
Volume ratio 3.5
Volume ratio 5.0

3.3.15 SAB 283 Mk1, SAB 330 and SAB 355 Mk1 with oil pump

The pump is used for prelubrication and to maintain a minimum oil pressure level during op-
eration. The pump is started and stopped in accordance with the compressor differential pres-
sure (discharge 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.
Set point 1 is the pump start pressure and Set point 2 is the pump stop pressure. Therefore,
Set point 1 must be set to the lowest pressure level.
Normal setting for SAB 283 Mk1/330/355 Mk1:
Set point 1 = 2.5 bar
Set point 2 = 4.0 bar
Move the cursor to Set point 1, press
adjust the value and then press
Adjust Set point 2 the same way.
If the compressor differential pressure is below Set point 1 during operation, the pump will
start immediately.
When the compressor differential pressure has been higher than Set point 2 for 60 sec, the
pump will stop.
45 sec.
300 sec.
300 sec.
300 sec.
Vi slide position
../Capacity/Vi slide
pos.
0.0 %
65.3 %
100.0 %
to enter the parameter change field, use
to store the value.
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Compressor control and surveillance
Dig. output 11 (V1) Dig. output 12 (V2)
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Off
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Engineering manual - Unisab III 1.10
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001930 en 2014.09