Vertiv Liebert EXL 31, Installer/User Manual

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1.2 Two UPS Units With Common Bypass Line
When two UPS's are connected with a common bypass line without the Liebert® Load Bus Sync Controller, the bypass line
synchronizes the inverters. Synchronization can be lost because of upstream protection of the bypass line. Using the Liebert
Load Bus Sync Controller as shown in Figure 1.3 below, the systems are always synchronized, even if one of the bypass
lines is out of tolerance, and are usually capable of synchronous operation.
NOTE: Install N.B. fuses at the beginning of the signal line to avoid fires in case of short circuit in the wires. Configure
both UPS systems with main synchronization source to bypass. Otherwise the UPSs will not be capable of
synchronous transfer to bypass.
Figure 1.3 Common Bypass Line
Vertiv™ | Load Bus Sync Controller Installer/User Guide
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