Johnson Controls SABROE UniSAB III Engineering Manual page 201

Set-up
The above is not relevant for plants consisting of reciprocating compressors without VSD only. See the
swept volume on the compressor name plate.
3: Volume ratio (screw compressors)
Manual
Auto
If selecting Auto, the compressor must be fitted with solenoid valves etc for automatic regulation of Vi
slide.
4: Fixed Vi ratio
1.4, 1.7, 2.2, 2.9, 3.4, 4.0
For SAB 157 HR high-pressure screw compressors of the HPSH type with fixed Vi ratio, select the cor-
rect Fixed Vi ratio for this compressor block. The fixed Vi ratio is stamped on the compressor block.
5:Vi comp. plug valve
No
Yes
Select Yes if you wish to use the plug valve to optimise the Vi ratio at part load in case the compressor is
operating at a lower Vi ratio than the block is designed for. This gives lower power consumption, but
might lower the maximum compressor capacity too.
Select No if you do not wish to use the plug valve to optimise the Vi ratio at part load.
6: Vi low range
Yes
No
Select Yes for types SAB 193 S - SAB 355 X with low volume range (1.7-3.0), SABflex and SABCube
compressors with low volume range. See volume range on compressor name plate. Select No for all
other compressor types.
7: Vi trig level
2.5/3.6
This setting is for SABflex and SABCube screw compressors. It defines the Vi trig level where the Vi
slide output is set to low or high. The Vi trig level depends on the setting of the Vi low range. Not
changeable.
Engineering manual - UniSAB III 1.10.8
001930 en 2021.06 201/346