Note 19
For SAB 80 the differential pressure across the oil filter is calculated as fol-
lows: (see Fig. 6) Oil filter diff. pressure = Discharge pressure 2 - Oil pres-
sure 4 (after oil filter).
The stated oil filter pressure will thus be 0.1 to 0.7 bar higher than the ac-
tual pressure loss across the filter due to the pressure loss across the oil
separator and the oil cooler.
The maximum allowed pressure drop across the oil filter is 1.2 bar. Conse-
quently, the alarm limit should be set between 0.8 and 1.4 bar or lower. The
shutdown limit should be set between 1.1 and 1.7 bar or lower.
Note 20
Set points 1 and 2 are used for shutdown monitoring of the mechanical oil
pump, see Engineering manual. For SAB 80, the oil pressure is calculated as
follows: (see Fig. 6) Oil pressure = Oil pressure 3 (after pump) - Suction
pressure 1.
Note 21
The set points are only used if the compressor is equipped with an electrical
oil pump. The set points are used to control the oil pump. When the differ-
ential pressure (discharge pressure - suction pressure) falls below set point
1, the oil pump will start. When the differential pressure exceeds set point 2
for 60 seconds, the oil pump will stop.
Note 22
The set points are used to control the full flow pump. When the pressure
falls below set point 1, the full flow pump will start. When the pressure ex-
ceeds set point 2 for 60 seconds, the full flow pump will stop.
Note 23
The set points are used for liquid slugging, alarm and shutdown. This alarm/
shutdown is released by a sudden decrease in discharge temperature which
is greater than the liquid slugging alarm/shutdown set point for a fixed 5-
second period. Set point 1 = alarm set point. Set point 2 = shutdown set
point.
Note 24
Oil temperature settings on heat pumps should be increased to:
High shutdown: 95
High alarm: 90
Low alarm: 55
Low shutdown: 50
Note 25
For SABflex and SABCube, the differential pressure across the oil filter is cal-
culated as follows: (see Fig. 6): Oil filter diff.pressure = Discharge pressure
2 - Oil pressure 3 (after oil filter). The shown oil filter pressure will thus be
0.1 to max. 0.5 bar higher than the actual pressure loss across the filter due
to the pressure loss across the oil separator and the oil cooler.
Note 26
For SABflex and SABCube, the internal suction pressure is measured as the
pressure after the suction stop valve.
The alarm and shutdown is only active when the compressor is running and
the start-up limiter is no longer active.
Note 27
For SABflex and SABCube, the pressure ratio is calculated as
Discharge pressure (abs) / Suction pressure (abs).
The alarm and shutdown is always active.
Operating Unisab III control
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Operating manual - Unisab III
005650-en 2013.10