Vertiv Liebert EXL 31, Installer/User Manual

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Figure 1.1 Controller Front and Rear Panels
ITEM DESCRIPTION
1 Front
2 Rear
1.1 Synchronization Control Configurations
1.1.1 Two Systems with Separate Utility Supplies
When two UPS's are connected to separate power sources without the Liebert® Load Bus Sync Controller, 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 is no
common input signal, and the outputs will not be synchronized.
With the Liebert Load Bus Sync Controller, one of the UPS outputs is the master, and the other UPS (slave) outputs follow
the master reference, see Figure 1.2 on the facing page.
NOTE: Install N.B. fuses in the phase signal line, upstream of the Liebert Load Bus Sync Controller to protect against
damage caused by short circuits. Configure UPS B, shown in Figure 1.2 on the facing page, so that it follows the
external synchronization signal by setting the main synchronization source to external signal. Otherwise, the UPS will
be in phase with its own bypass line and follow external synchronization only when this is out of tolerance.
Vertiv™ | Load Bus Sync Controller Installer/User Guide
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