G-Tec LibraPro, User Manual

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Pag. 46 / 57 0MNLIBRAPROK10NPENUA 01
4.6 Operating modes
Several LIBRAPRO units connected in parallel share the current absorbed by the load between them.
In a system with several UPSs connected in parallel, there is a single Master unit and the remaining units will be
SLAVES. The UPSs are all exactly the same and the Master is chosen on start-up. The Master unit is shown on the
display panel by the capital letter “P” (or “B” in the case of a single battery). The MASTER and SLAVE units may
exchange roles. If a unit goes out of service, e.g. due to an inverter fault, it will automatically be excluded. The load
at this point is shared between the units that are still active; if the power in output is excessive for the remaining
UPSs, the system logic switches all the units, including the UPS that was excluded, onto the by-pass line.
All the information contained in the section on “operating modes” (page 28 ) in relation to the UPS remains valid
with the addition of the information set out below.
ON LINE OPERATION
The message: “NORMAL OPERATION” is shown on the display panel of each UPS and the letter “P” appears in
the bottom left-hand corner near the indication of the model. This letter is in upper case if the equipment in question
is the MASTER while a lower case character is displayed if the UPS is a SLAVE.
STAND-BY ON OPERATION
The sharing of the load between the UPSs is linked to the length of the cables, and the rules on the length of the
connections indicated in the section “connections” must be observed. In the event of a mains power failure, the load
is passed onto all the parallel-connected UPSs.
STAND-BY OFF OPERATION
In this mode, if there is a mains power outage, the devices share the load equally; the load is not powered with the
mains present.
STABILIZER WITHOUT BATTERY OPERATION
In this mode, the devices share the load equally.
BATTERY OPERATION
One battery for each UPS
Each unit draws the energy from its own battery. At the end of its backup time each UPS excludes itself. The load
remains unpowered if the duration of the mains outage is greater than the backup time of the whole system. When the
mains is restored the system will restart automatically. Each UPS recharges its own battery.
One battery for all the UPSs.
Each unit draws the energy from the common battery. At the end of the backup time, the whole system excludes
itself. The load remains unpowered if the duration of the mains outage is greater than the backup time of the whole
system. When the mains is restored the system will restart automatically. Each UPS recharges the common battery.
OVERLOAD
In this mode too, the devices share the overload equally.
If the load applied to the system is not reduced, the whole system will switch onto the by-pass line. When the
overload is removed, all the units will automatically return to normal operation. If the overload persists, however, it
triggers the external protection devices located at the UPS input on the by-pass line. In this case the load would
remain unpowered.