Connecting External Battery Cables - Liebert NXC User Manual

Parallel UPS Installation and Commissioning

3.3.3 Connecting external Battery Cables

All the UPSs in parallel system can either share the battery strings, or use battery strings independently.
Each UPS should be equipped with the independent battery MCB. Refer to Table 2-4 for selection of the battery MCB.
Using battery string independently
When each UPS of the parallel system uses the battery string independently, the battery cables connection of each UPS in
parallel system is the same with that of the single UPS, refer to 2.4.2. The schematic diagram of battery strings in 1 + 1 parallel
system when using battery string independently is shown in Figure 3-3.
Make sure that the LCD settings are correct when using the battery strings independently, refer to 3.4.2 for details.
first Block
first Block
first Block
first Block
Sharing battery string
Using the shared battery string in parallel system can save investment in equipment for users.
To ensure the abundant backup time of the battery, it is recommended to use the external battery cabinet with big capacity.
1. Wiring
Power off the parallel system completely, disconnect the battery MCBs of all single UPSs, and then use battery cables (refer to
2.4 for the cables and the MCBs) to connect '+', 'N', '-' and 'PE' terminals of the battery string respectively to 'Bat +', 'Bat N',
'Bat -' and 'PE' terminals of the corresponding UPS I/O terminal block in parallel system through each battery MCB, as shown in
Figure 3-4.
30
second Block
third Block
second Block
third Block
second Block
third Block
second Block
third Block
Figure 3-3 Connection principle diagram upon using battery strings independently
Note
Note
sixteen Block
sixteen Block
sixteen Block
sixteen Block
Note
User Manual 10H52188UM51 - Rev. 1 - 09/2011
Liebert NXC
UPS 1
Bat +
Bat N
output
Bat -
UPS 2
Bat +
Bat N
output
Bat -