Salicru SLC CUBE 4 7.5 kVA Mode D'emploi page 128

8. PARALLEL SYSTEM
8.1. INTRODUCTION
The SLC CUBE4 series of uninterruptible power supply (UPS) sys-
tems are designed to be connected in parallel, up to a maximum of
four units and provided they are of the same model (configuration,
voltage, power, frequency, backup, etc.), without the need for any
additional hardware.
In conceptual terms, and notwithstanding their potential configura-
tions, parallel systems are divided into two structures that are very
similar to each other yet also very different, from the perspective
of their application.
Systems connected in parallel or active parallel share the burden
of supplying power to the loads equally, unless the facility only has
one UPS. The system may or may not be redundant, depending on
the needs and requirements of the application.
Simple (non-redundant) parallel
•
system is one in which all of the UPSs supply the power re-
quired by the loads. The total power of a system comprised of
n devices with a power rating
If the system is working with a load that is near to or at the
maximum, and one of the UPSs fails, the load will be automati-
cally transferred to the bypass without a zero crossing; as a re-
sult, the power demand cannot be met, owing to the overload
that will inevitably occur in the rest of the UPSs.
Redundant system: a redundant system is one that has one
•
or more UPSs meeting the minimum total power requirements
for the system (depending on the level of redundancy), with the
load shared equally between them.
Thus, if one of the UPSs fails, it will be isolated from the
system and the rest will continue to supply the load with all
due guarantees. Once the faulty UPS has been repaired, it can
be reconnected to the system and provide redundancy once
again.
A system with this configuration provides increased reliability
and ensures a high-quality AC supply for more critical loads.
The number of redundant devices that should be connected to
the system must be calculated in accordance with the needs
of the application.
structure. N represents
the total load needs;
devices, i.e. the number of faulty UPSs that the system can
allow simultaneously. The higher
of the system. For occasions where reliability is essential,
will be the optimum mode.
128
system: a non-redundant
Pn is n x Pn.
N+X is usually the most reliable power
the minimum number of devices that
X represents the number of redundant
X is, the greater the reliability
8.2. INSTALLATION AND CONNECTION.
To install a parallel system correctly you must follow the recom-
mended installation diagram for
When installing the parallel system, it is necessary to incorporate
a board equipped with individual protections for input, output and
static bypass (the latter for the version with independent bypass
input), as well as a manual bypass with mechanical locking. See
and .
In the event of an anomaly of any kind, this protection board will
enable a single device in the system to be isolated in the event of
a fault and the loads to be powered by the rest while the device is
being repaired, or during preventive maintenance. It will also make
it possible to remove a device from the parallel system and replace
it or reconnect it once fixed, while ensuring the loads remain con-
stantly supplied.
Upon request, we can supply a manual bypass board for a parallel
system where it is needed.
By way of example, provides an illustration of the diagram to
follow in order to install a parallel system without an independent
bypass line:
N+X
SLC-CUBE4
series devices.
SALICRU