Lbs Configurations; Normal Operations; Slave Priority; Master System - Vertiv Liebert NXL Series Operation And Maintenance Manual

3.4.2

LBS Configurations

• Load Bus Sync – Enable or Disabled (default: Disable)
• LBS Master Select - Master or Slave (default: Slave)
NOTE
The LBS settings permit proper operation with only one UPS set as the Master unit.
• LBS Slave Priority – 0 to 7 (default: 0)
NOTE
Setting of '0' will disable LBS Slave Priority
3.4.3

Normal Operations

The LBS will synchronize the Designated Slave Systems (DSS) to the Designated Master System (DMS). The
DSS will synchronize to the DMS output if the DMS is in Normal, Battery, Bypass or Maintenance Bypass Mode
If the DSS transfers to Bypass Mode or Maintenance Bypass mode, the DMS will then synchronize to the output
bus of the DSS. This re-selection of master will be accomplished automatically.
3.4.4

Slave Priority

When Slave Priority is enabled, the LBS system will work the same as Normal operations (See 3.4.2 - LBS
Configurations except when the DMS disqualifies it bypass source. If the DMS's bypass is disqualified, the LBS
system will synchronize to the output of the DSS with the lowest Slave Priority number that has a qualified
bypass. The LBS system will synchronize back to the DMS when the DMS's bypass is qualified or all DSS's
bypass are disqualified.
If a DSS LBS Slave Priority is set to "0", it will not assume the synchronization of the system if the DMS
disqualifies its bypass.
Figure 53 LBS configuration
Load Bus Sync
LBS Master Select
LBS Slave Priority
Ensure each system has
a unique slave priority!
Save
3.4.5

Master System

The unit designated at power-up/reset to be the Master will monitor the LBS Sync Pulse line.
If two units are designated as Master, the second designated Master Unit to come on-line will inhibit the LBS and
sync to its own bypass.
The LBS Master will monitor the LBS Sync Pulse continuously; if the LBS Master detects that another unit has
transferred to bypass, the LBS Master will follow the unit on bypass.
• Slave can no longer follow the Master; the Master must follow the Slave.
When the Master unit is following a Slave LBS Sync Signal, it will generate the LBS Active event.
If the Slave LBS Sync Pulse stops, the Master will resume generating the LBS Sync Pulse.
Vertiv | Liebert ® ™
NXL
Dis
En
Slave
Master
0
Cancel
250-1100kVA, 60Hz, Three Phase, SMS & MMS UPS Operation and Maintenance Manual
LBS Slave Priority
Min
0
0
Down
Ok
Options
Max
7
Up
Cancel
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