Salicru SLC CUBE 3+ PS Mode D'emploi page 112

Although, in practice it can drain the total power in that the
N+M system can supply, the redundancy requirement or con-
ception does not advice it and in compensation there is a sur-
plus of dynamic power against load demands.
I.e., a redundant parallel system with 3 UPS of 40 kVA and N+1
configuration, the nominal maximum load contemplates 80
kVA (2x40 kVA), although the system can accept load demands
up to 120 kVA (3x40 kVA).
Therefore, the fact of having +M reserve equipments, in-
creases the back up time of the set, because the battery set
is higher.
Modularity: capacity can be added to a UPS parallel system
•
by adding equipments of the same feature, without needing to
replace the equipments already installed.
I.e., if time later, an installation with a parallel system of 2 UPSs
is detected that the capacity of this system is not enough,
it can be opted for adding a third equipment to the system,
without replacing the 2 original equipments.
The UPS parallel system management of SLC CUBE3+ PS series
is done by a MASTER-SLAVES protocol, where only one equipment
(MASTER) takes the control of the rest ones (SLAVES). So, the con-
trol of the output voltage, bypass shifting, disconnections, mains
synchronisation, ...; are managed by the MASTER equipment, and
transmitted to the SLAVES equipments through the management
bus of the parallel system.
This MASTER or SLAVE condition is dynamic as it is described later
and it will depend on several factors (initial status of the equip-
ments, chronological order of commissioning or shutdown of the
system through one equipment or other one, ...)
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