Chapter 7 Parallel System And Lbs System; General; System Installation Procedures; Preliminary Checks - Liebert NXC 30kVA User Manual

Chapter 7 Parallel System And LBS System

This chapter gives details on the installation of parallel system and LBS system.

7.1 General

The parallel system can comprise of up to four UPS modules of the same power rating and connected in parallel
without the need for a centralized mains static bypass. Instead the bypass static switches of each UPS share the load
when the system transfers to the mains bypass supply.
From a 'power' viewpoint, each module is internally identical to the 'single module' configuration. A parallel system
requires inter-module control signals to manage the load sharing, synchronizing and bypass switching. The control
signals are connected through the parallel cables, which are multi-way ribbon cables connected between the units of
the system to form a ring.
When two or more modules are to be connected in parallel, it is recommended that inductor should be inserted in the
static bypass line. This can be installed internal to the UPS as an option.

7.2 System Installation Procedures

The basic installation procedure of a parallel system comprising two or more UPS modules is the same as that of
single module system. This section only introduces the installation procedures specific to the parallel system. The
installation of a parallel UPS should follow the installation procedure for a single UPS module with the additional
requirements detailed in this section.

7.2.1 Preliminary Checks

Be sure that the options of the parallel cables are correct, and that the modules are of the same rating, model, and with
the same software and hardware release.
To achieve coordinated operation of the modules in the parallel system, it is required to configure each module separately using
Emerson setting software. This must be done by Emerson service personnel.

7.2.2 Cabinet Installation

Place the UPS modules side by side and interconnect as shown in Figure 7-1. The output distribution mode (Q1EXT,
Q2EXT must be configured) shown in Figure 7-1 is recommended to facilitate maintenance and system testing.
Liebert NXC 30kVA And 40kVA UPS User Manual
Chapter 7 Parallel System And LBS System
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