Johnson Controls SABROE Unisab III Control User Manual

2.2.29 Oil log shutdown
GSV/RWF/SGC compressors with oil pump
This shutdown protects against overcharging the compressor with oil. The oil pump is started
at compressor start-up if the capacity slide is above 5%. The purpose of this is to increase oil
pressure and thereby run the slide into minimum position. If capacity is not below 5% before
the oil log shutdown timer runs out, a shutdown will be issued for the Oil log shutdown. Note
that there is a risk of overcharging the compressor with oil which may damage it at next
start-up if the timer is set too high.
2.2.30 Insufficient main oil pressure alarm
SGC compressors (SAB 157 HR)
This alarm is released if the oil pressure is < [1.5 x P
suct
] + 1 bar. The alarm delay is 180 sec-
onds. When the main oil pressure is too low, the limiting function Insufficient main oil pres-
sure (SAB 157HR) will unload the plug valve, with no delay. See Fig. 9 and subsection
3.2.3. Special limiters.
2.2.31 Insufficient main oil pressure shutdown
SGC compressors (SAB 120→151 and SAB 193→355)
This shutdown is released if the oil pressure is < [1.5 x P
suct
] + 1 bar and at the same time
the capacity slide is above 50%. The shutdown delay is 180 seconds. When the oil pressure is
too low, this function limits capacity to max. 50% and the capacity cannot increase if it is be-
tween 40 and 50%. For screws with both capacity slide and frequency converter the limitation
only affects the capacity slide not the VSD. See Fig. 8.
2.2.32 Low oil circuit pressure alarm
SGC compressors (SAB 120→151, SAB 157 HR, SABflex and SAB 193→355)
This alarm is issued if the pressure difference between discharge pressure minus oil pressure
exceeds 2.7 bar. The alarm delay is 600 seconds. See Fig. 10.
2.2.33 Low oil circuit pressure shutdown
SGC compressors (SAB 120→151, SAB 157 HR, SABflex and SAB 193→355)
This shutdown is issued if the pressure difference between discharge pressure minus oil pres-
sure exceeds 3.0 bar. The shutdown delay is 900 seconds. See Fig. 11.
2.2.34 Critical oil circuit pressure shutdown
SGC compressors (SAB 120→151, SAB 157 HR, SABflex and SAB 193→355)
This shutdown is issued if the pressure difference between discharge pressure minus oil pres-
sure exceeds 5.0 bar. The shutdown delay is 25 seconds. See Fig. 12.
2.2.35 Oil pump low pressure alarm
SGC compressors (SAB 120→151, SAB 157 HR and SAB 193→355)
This alarm is issued if the pressure difference between oil pressure and discharge pressure is
less than a preset value, see table Table 8: Measured and calculated pressure levels - screw
Alarms and shutdowns
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Engineering manual - Unisab III 1.10
001930 en 2014.09

Johnson Controls SABROE Unisab III Control Specifications

General

Brand	Johnson Controls
Model	SABROE Unisab III Control
Category	Control Systems
Language	English