32 Chapter 3 Parallel UPS Installation And Commissioning
Liebert
®
ITA 16kVA And 20kVA UPS User Manual
Sharing battery strings
Using the shared battery strings in the parallel system can save investment in equipment for the users.
Note
1. If the battery strings (four standard battery modules, option) are shared in parallel system, the backup time of the battery module
ranges from two minutes to three minutes at full load.
2. 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 2.5 Connecting Power Cables for the cables and the MCBs) to connect ‘+’, ‘N’, ‘-’ and ‘PE’ terminals
of the battery strings respectively to ‘Bat +’, ‘Bat N’, ‘Bat -’ and ‘PE’ terminals of the corresponding I/O terminal block
of the UPS in the parallel system through each battery MCB, as shown in Figure 3-5.
PE
UPS 1 UPS 2
UPS 1 MCB
UPS 2 MCB
+- PE
Positive battery
string
+-PE
Bat+ Bat N Bat- Bat+ Bat N Bat- PE
Negative battery string
Figure 3-5 Connection diagram of shared battery string in 1 + 1 parallel system
Refer to Figure 3-6 to configure the positive battery string and negative battery string.
＋
－
First cell
Bat +
Battery module
＋
－
＋
－
＋
－
……
Bat -
PE
Battery cabinet
Second cell Third cell Sixteen cell
Figure 3-6 Internal connection diagram for positive battery string and negative battery string
2. Setting
Power on the system, set each single UPS to shared battery strings configuration through the LCD menu ‘Settings’ ->
‘Shared Battery’ from each UPS; set the LCD menu ‘Settings’ -> ‘Battery Cells Number’ and ‘Single Group Batt Cap’
from each UPS, and each UPS setting must be the same, as shown in Figure 3-7.
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