Johnson Controls SABROE UniSAB III Engineering Manual page 183

Set-up
• UniSAB no. 1 has the same System no as UniSAB no. 2
• UniSAB no. 3 has the same System no as UniSAB no. 4
• System no of UniSAB 1 and 2 differs from System no of UniSAB 3 and 4
In the right example each of the four compressors can be independently connected to any of the two
suction main lines. In this example is also important that System no is correct. However, it is particularly
important that when changing the valve settings, the System no of the relevant UniSAB III units is
changed accordingly as this does not happen automatically.
Start no defines the priority of the compressors with a common System no. The unit with the lowest
Start no will be the first to start. Multisab Master must be identical for all units with the same System no.
See section 6.4 Configuration. Multisab Master specifies whether the Compr. no or the Start no should
define which UniSAB III will be the system regulator (System regulator).
System regulator is responsible for the co-ordination of the involved units. The sensor of the System
regulator (e.g. suction pressure input) is used for the regulation. If Multisab Master = #Compr the unit
with the lowest Compr. no will be System regulator except if the UniSAB III unit in question is shut off or
otherwise unable to communicate. In this case the unit with the next Compr. no will take over as System
regulator.
If Multisab Master = #Start the unit with the lowest Start no will be System regulator but only as long as it
is available. If it is not available the unit with the next Start no will take over as System regulator.
A unit is not available if it is shut off, not communicating, not in Remote mode or in shutdown alarm con-
dition. An alarm condition may be caused by a sensor error resulting in a change of System regulator
and thus of sensor.
In order for a compressor to become part of a Multisab system, the above key parameters must be set
up. Control Mode must be set for Remote. In other words, the user can include and exclude the com-
pressor from the Multisab system by changing Control Mode. See section 3.1 Compressor regulation
set-up.
Engineering manual - UniSAB III 1.10.8
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