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0MLMHTM30RUENUA
7
Parallel (OPTIONAL)
7.1
UPS in parallel configuration
7.1.1 Introduction
UPS’s with parallel option fitted may be connected in a parallel configuration to increase both the reliability of the
power supply to the load and the available output power. Up to 8 UPS’s can be parallel-connected. It is recommended
to connect units of the same power.
The load that can be applied to a system with several
units connected in parallel may be greater than the
load that can be supplied by a single unit, thanks to
automatic load sharing. The maximum reliability is
achieved when the total power of the system with one
unit OFF remains greater than the required power.
This condition can be achieved by always adding a
redundant unit
(N+1)
.
Redundant unit means UPS with more than the
minimum number of elements required to power the
load, so that if a faulty unit is automatically excluded,
rated power is still supplied. The UPS’s connected in
parallel are managed by a logic board which ensures
the interchange of information. The information is
exchanged between the UPS’s via a cable connecting
them in a loop. The loop connection provides
redundancy in the network connection cable
(communication in the cables between the individual
units). This is the most reliable means of connecting
the UPS and also allows the “hot” insertion or
disconnection of a UPS. Each UPS has its own controller that continuously communicates with the whole system so as
to guarantee the operation of the system. The cable transmits the signals from a “Master” UPS to the other “Slaves”
using an optically-isolated system in order to keep the control systems electrically isolated from each other. The logic
operate so that the first unit activated becomes the “Master” and takes control of all “Slave” units. In the event of a fault
in the “Master” unit, control is immediately switched to a “Slave” which then becomes the “Master”. The current
system provides basic operation, each unit having its own battery. The system may be customized (by insert a code on
the display panel) with all the units connected to a single battery.
Note: For parallel system greater than 1+1 redundant, it’s recommended to install the wrap around bypass switch. This
is to assure the correct maintenance.
