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0MLMHTK65RUENUB
INVERTER
This is the output stage, its function is to convert the DC voltage from the RECTIFIER or from the BATTERY into
stabilized sinusoidal AC voltage. The inverter output is isolated from the input and from the batteries by a galvanic
isolation transformer. The inverter is always working; since the load connected to the UPS output is always
powered by the INVERTER (in NORMAL OPERATION)
STATIC SWITCH
This device allows the synchronized switching, automatic or manual, and in zero time, of the voltage to the load
from a protected source (inverter output) to an unprotected source (bypass line) or vice versa.
The UPS is provided with a device to prevent the backfeed of voltage to the input line after an internal fault, known
as “
BACKFEED PROTECTION”.
Mechanical BYPASS (SWMB )
This is a mechanical bypass switch. The UPS can be bypassed by closing SWMB and opening switches (SWIN,
SWBY and SWOUT) while keeping the load on the output powered. This operation is necessary when maintenance
operations must be carried out inside the equipment without interrupting the power supply to the load.
The mechanical bypass switch is sized for the rated power of the UPS.
UPS in parallel configuration
1.1.22
Introduction
UPS’s 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 supported by each individual unit, thanks to
automatic load sharing. The reliability is only
increased provided that the total power of the system
with one unit deactivated remains greater than the
required power. This condition can be achieved by
always adding a redundant unit
(N+1)
.
Having a redundant unit means having one more UPS
than the minimum number of elements required to
power the load, so that if a faulty unit is automatically
excluded, adequate power is still supplied. The UPS’s
connected in parallel are coordinated by a card 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 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 operating
logic envisages that the first unit that is activated becomes the “Master” and takes control of the other “Slaves”. 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
personalized (by means of a code inserted on the display panel) with all the units connected to a single battery.