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5.3.2 Cabinet Installation
Parallel system composed of two or more UPS modules using parallel cabinet
The UPS modules that will form the parallel system should be placed side-by-side. Each battery
cabinet is placed next to its corresponding UPS module.
The parallel cabinet should be placed in the middle of the system.
5.3.3 Preliminary Checks
Each UPS module should have the same firmware and the same hardware version. Refer to the
instructions in 5.3.1 - Conditions for Parallel System.
5.3.4 Power Cables
Wiring of power cables is similar to that of a single module system (See 3.1 - Power Cabling). The
bypass sources of all modules should be the same, and the outputs should be connected altogether
correctly.
Power cables are field-supplied. Power cables to the UPS’s of the paralleling cabinet must be routed
through either the top or bottom entry access of the UPS.
5.3.5 Parallel Control Cables
Parallel System Control Cables
Make the connections listed below on the parallel logic board (M3) inside the Liebert NX. (See
Figure 30 for the location of the parallel logic board):
Shielded and double-insulated control cables, available in lengths of up to 100 feet (30m), must be
interconnected in a ring configuration between UPS modules as shown below. The ring configuration
ensures high reliability of the control (refer to Figure 17).
Figure 17 Connecting system parallel control cables
NOTE
The system input and/or output circuit breaker is to be field-supplied. See Table 8 for current
rating.
NOTE
The length and specifications of power cables including the bypass input cables and UPS
output cables should be the same, thus the load can be shared evenly in bypass mode.
X1-1 X1-2
X2-2 X2-1
Parallel Board
X4
X3
P5
P3
P4 P1
P2
X1-1 X1-2
X2-2 X2-1
Parallel Board
X4
X3
P5
P3
P4 P1
P2
X1-1 X1-2
X2-2 X2-1
Parallel Board
X4
X3
P5
P3
P4 P1
P2
X1-1 X1-2
X2-2 X2-1
Parallel Board
X4
X3
P5
P3
P4 P1
P2
1 2 3 4
UPS
Interconnecting
Cables