Johnson Controls SABROE UniSAB III Engineering Manual page 329

Troubleshooting
Version no.
1.1.0.2 A new small screw compressor type has been introduced - SABflex 159.
It is a frequency controlled screw compressor with an SSTV suction valve for torque
limitation.
It is now possible to set up Modbus RTU communication with Danfoss VSD drive. Used
for SABflex.
For SAB 120 to 355, the default oil filter diff. pressure settings have been changed. The
high alarm limit is lowered from 1.7 bar to 1.2 bar, and the high shutdown limit from 2.0
bar to 1.5 bar.
The following Multisab situation involving a Rota screw and a standard screw has now
been corrected. In a situation where Multisab has calculated that the Rota can take
over, and the regulated process value is inside the lower P band, the screw will regu-
late down in capacity to let the Rota take over. If however, during the take over, the
regulated process value gets inside the neutral zone, the take over process will be
stopped.
The following Multisab situation involving three or more Rota screws has now been cor-
rected. In a situation where more than two Rota screws are running, the parallel stop
capacity (of the last Rota) was not calculated correctly. Three Rota compressors might
in this situation run at 50% each, where the optimum would be to have two Rota com-
pressors running 75% each.
The function Capacity output AO1 now works for standard reciprocating compressors
too.
HPC compressors with a combination of High discharge alarm and the High differential
pressure limiter being active, would sometimes very quickly reduce capacity from 75%
to 50% and then stop. This problem has been corrected.
Engineering manual - UniSAB III 1.10.8
001930 en 2021.06
Description
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