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User Manual 10H52188UM51 - Rev. 1 - 09/2011
Parallel UPS Installation and Commissioning
Liebert NXC
3.3.1
Connecitng I/O Cables
The UPS power cables are connected to the I/O terminal block of the UPS rear panel, the layout of the I/O terminal block is
shown in Figure 2-3.
Power distribution mode
The I/O cable connections are divided into four types: 3-in 3-out, common source configuration (factory default), 3-in 3-out,
split-bypass configuration, 3-in 1-out, common source configuration, 3-in 1-out, split-bypass configuration. The input and
output cable connection procedures of the four power distribution modes are as follows.
Distribution for the parallel system
The block diagram of three UPSs parallel system is shown in Figure 3-1. Refer to Power distribution mode in 2.4.1
for
the cable
connection of each UPS. Refer to 2.4 for the input and output, battery MCB and cables when using the customer
self-distribution mode.
Figure 3-1 Block diagram of three UPSs parallel system
Warning
Each UPS must configure extenal input MCB and extenal output MCB when carring out the power distribution for the parallel
system, as shown in Figure 3-1.
Changing power distribution mode
This product is compatible with 3-in 3-out/3-in 1-out, factory default: 3-in 3-out.
Carry out the parallel connection after changing the single system to the needed system (refer to Changing power distribution
mode in 2.4.1 for the changing method), if you need to change the mode from 3-in 3-out to 3-in 1-out or from 3-in 1-out to
3-in 3-out.
3.3.2
Connecting Parallel Cables
The parallel system provides the parallel cable option. The parallel cables form a ring connection through the parallel ports on
the UPS rear panel. The cable connection schematic diagram of 3 + 1 parallel system is shown in Figure 3-2. The first port on the
left is DB9 male port (needle shape), and the second port on the left is DB9 female port (hole shape).
User input power
distribution unit
User output power
distribution unit
Input cable
Output cable
