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Installation
The basic installation procedure of parallel system is
the same as that of single module system. The fol-
lowing sections only introduce the installation proce-
dures specific to the parallel system.
Cabinet Installation
Parallel system composed of two UPS modules
The two UPS modules that will form the 1+1 system
should be placed side-by-side. Each battery cabinet
is placed next to its corresponding UPS module.
Preliminary Checks
Each UPS module should have the same rating, the
same firmware and the same hardware version.
Refer to the instructions in Conditions for Paral-
lel System on page 1.
Protective Devices
Refer to the instructions supplied in the Liebert NX
installation manual, SL-25215.
Power cables
Wiring of power cables is similar to that of single
module system (see the Liebert NX installation man-
ual, SL-25215). The bypass sources of all modules
should be the same, and the outputs should be con-
nected altogether correctly.
Parallel Control Cables
Make the connections described below on the paral-
lel logic board (M3) inside the Liebert NX:
• Connect one end of the DB-25 interconnecting
cable to the X2_1 connector of UPS 1 and the other
end to the X2_2 connector of UPS 2.
• Connect one end of the DB-25 interconnecting
cable the X2_2 connector of UPS 1 and the other
end to the X2_1 connector of UPS 2.
• Connect one end of the DB-9 interconnecting cable
the X1_1 connector of UPS 1 and the other end to
the X1_2 connector of UPS 2.
• Connect one end of the DB-9 interconnecting cable
the X1_2 connector of UPS 1 and the other end to
the X1_1 connector of UPS 2.
The connections are shown above in Figure 2.
Figure 2 Connecting 1+1 system parallel control
cables
Commissioning a Parallel System
Check the input and output wiring of each UPS mod-
ule. Ensure that the phase rotation sequence of the
main inputs and the bypass inputs and outputs of
each UPS module are the same. Ensure the parallel
cables are connected firmly.
It is assumed that the installation is complete, the
system has been commissioned by authorized per-
sonnel and the external power isolators are closed.
Before startup, disconnect the load.
Start the UPS modules separately and set the
parameters of each UPS module through configura-
tion software. Pay particular attention to the param-
eters directly relevant to the parallel system:
• UPS Configuration: Each UPS module belonging
to the parallel system should be set as Parallel
configuration.
• UPS ID No.: Each UPS module should have a
unique identification number in the parallel system.
• Parallel system requisite UPS units: Set the mini-
mum number of UPS modules to support the
user’s expected load. For 1+1 systems this settings
needs to be set to 1.
• Parallel system redundant UPS units: Set the
redundant number of UPS modules which will not
cause the parallel system transfer to bypass even
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.
!
CAUTION
The operations in this section must be
performed by authorized electricians or
qualified technical personnel. If you have
any difficulties, contact Liebert Global
Services at 800-543-2378.
#1 UPS Module #2 UPS Module
Parallel Board Parallel Board
X5
X4
X2-2X2-1X2-2X2-1
X4
X1-1 X1-1X1-2 X1-2
1 2
4
3
Interconnecting Cables
1 2
Parallel Connection Board
UPS Unit
4
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