Vertiv Liebert EXL S1, Operation And Maintenance Manual, Page: 29 / 131

2.3.2 Load Transfer-1+N System: Transfer System Inverter to Bypass
This section lists typical step-by-step instructions to transfer the UPS system from Inverter Mode to Bypass Mode.
The critical load should be on the UPS Inverter.
1. From the Touchscreen Control Panel of any UPS module in the system, touch OPERATE > UNIT OPERATIONS >
Inverter Off > System .
2. Verify that each UPS automatically transferred to Bypass.
NOTE: The load will now be on static bypass in each UPS.
2.3.3 Load Transfer-1+N System: Transfer System from Bypass to Inverter
This section lists typical step-by-step instructions to transfer the UPS system from Bypass to Inverter mode of operation.
The critical load should be on the UPS Bypass.
1. From the Touchscreen Control Panel of any UPS module in the system, touch OPERATE > UNIT OPERATIONS >
Inverter On > System .
2. Verify that each UPS automatically transferred to Inverter.
2.3.4 Load Transfer-1+N System: Remove a UPS from System (Collective)
NOTE: UPS modules must be de-energized with MOB open or be in Test Operation Mode once removed from the
collective bus.
1. Verify that enough UPS modules will remain present to support the load if one module is removed from the
collector bus.
2. From the Touchscreen Control Panel of the UPS module that will be removed from the collective, select
OPERATE > UNIT OPERATIONS > Inverter Off > Single . Confirm the operation when prompted.
3. Open the Module Output Breaker (MOB) of the UPS module to be removed from the collective bus.
4. Verify that the Inverter for the module to be removed from the collective turns Off. The other UPS modules in
the system should be supporting the load.
5. Open the Module Battery Disconnect(s) (MBD) of the module that was removed from service.
6. Open the optional internal Back-Feed Disconnect (BFD), if installed, of the module that was removed from
service.
7. Open the upstream feed breakers (RBB, RFB) to the UPS rectifier and bypass buses. The UPS module rectifier
will shut Off.
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