36 Chapter 3 Parallel UPS Installation And Commissioning
Liebert
®
ITA 16kVA And 20kVA UPS User Manual
UPS 1
Bypass
Bypass input
Main input
UPS 2
UPS 3
UPS 4
Output
LBS cable
Parallel cable
Connect to load
STS
Note: UPS1 and UPS2 are master system, UPS3 and UPS4 are slave system
Bypass input
Main input
Main
Bypass
Main
Bypass
Main
Bypass
Main
Output
Output
Parallel cable
Output
Figure 3-9 LBS system schematic diagram
Note
Refer to 3.4.2 Connecting Parallel Cables and 3.5 Commissioning Parallel System respectively for the settings of the DIP
switch and the parallel commissioning.
3.6.2 Installing External Protective Device
See 2.3 External Protective Device for details of installation and type selection.
3.6.3 Connecting Power Cables
In double bus system, refer to 2.5 Connecting Power Cables and 3.4 Connecting Power Cables to select the
power cables for single UPS and parallel system respectively. The bypass input power and main input power must
use the input terminal of the same neutral line. If the input terminal has leakage current, the leakage current
protective device should be installed before the input terminal.
3.6.4 Connecting LBS Cables
In double bus system, connect the two ends of the LBS cable to any LBS port of the two parallel systems respectively,
as shown in Figure 3-10. The third port on the left is DB9 male port (pin shape), the fourth port on the left is DB9
female (hole shape).
Note
1. The appearances of the LBS ports (see Figure 1-3) and the parallel ports (see Figure 1-3) are same, but the positions are
different. Be careful when inserting and connecting to avoid incorrect connnection.
2. For the double bus system formed by the parallel UPS, it is recommended to prepare two LBS cables, one is used to connect
any two LBS ports of the two parallel system, the other is redundant cable which is used for reliable connection.
3. As shown in Figure 3-10, one cable is LBS cable, others are parallel cables.
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