Vertiv Liebert Load Bus Sync Controller, User Manual

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Vertiv
™
| Liebert
®
Load Bus Sync
™
Controller Installation Manual | 5
2.0 TYPICAL CONFIGURATIONS
2.1 Two Systems with Separate Utility Supplies
When two UPS’s are connected to separate power sources, the inverters attempt to synchronize
with their respective bypass lines, but the lines may not be in phase, so synchronization cannot be
guaranteed. Even if the two units are supplied from a common line, when one or both is operating
on-battery there will be no common input signal, and the outputs will not be synchronized. When
the Liebert
®
Load Bus Sync
™
Controller is installed, one of the UPS outputs must be chosen as the
master, all the other UPS (slave) outputs will then follow this reference: see Figure 3 for details.
Figure 3 Two separate utility supplies
N.B. fuses should be installed in the phase signal line, upstream of the Liebert
®
Load Bus Sync
™
Controller to protect against the damage caused by short circuits. Installation tips: UPS B should
be configured so that it follows the external synchronization signal. This is achieved by setting
the main synchronization source to external signal. Otherwise, the UPS will be in phase with its
own bypass line and will follow external synchronization only when this is out of tolerance.
Power Source A Power Source B
Slave Master
UPS A UPS B
Source
Line B
Source
Line A
Static Switch
To Others
Static Switch
To Load
To Others
Static Switch
Liebert
®
Load
Bus Sync
™
Controller