1
Liebert
®
NX
™
1+1 System
Product Specification/Installation Sheet
General
The Liebert NX UPS uses intelligent and reliable
decentralized technology to achieve parallel
operation of two modules of the same rating.
The 1+1 system is used to:
• Increase the reliability of the system to ensure
adequate power supply to the critical load.
• Increase serviceability and allow the execution of
maintenance operations and reparations without
affecting the ordinary operating conditions of the
system (depending on the redundancy level).
Conditions for Parallel System
1. Each UPS module should have the same rating,
the same firmware and hardware version.
2. Each UPS module must have the same bypass
source.
3. The outputs of all UPS modules are connected
altogether.
4. The main inputs can be from different sources,
but the phase rotation sequence of main inputs,
bypass inputs and outputs must be correct and
the same.
5. The parallel logic cable and load sharing cable
must be connected in a ring correctly (see
Figure 2).
Features of Parallel System
1. The hardware and firmware for parallel UPS
module operation is standard in the Liebert NX,
and the configuration can be set up by changing
the settings in configuration software.
2. It is easy to install the parallel cables in a ring,
providing high reliability and redundancy. And
the intelligent paralleling logic provides the user
with maximum flexibility. For example, shutting
down or starting up the UPS modules in the
parallel system can be done in any sequence. If
an overload transfer occurs, the whole system
can recover automatically from bypass mode
after the overload is cleared.
3. The total load of the parallel system can be
queried from each module’s LCD screen.
4. Optional monitoring background software can
treat the entire parallel system as a big single-
module UPS, and provide corresponding
management. It can also get the information for
all modules by connecting to just one of the
modules.
!
CAUTION
An external maintenance cabinet is
strongly recommended to maintain the
power supply to load in case of complete
maintenance.
To Next Page
Need help?
General