70 Chapter 7 Parallel System & Dual Bus System
NX UPS Single Module And Parallel System 250kVA ~ 800kVA User Manual
Chapter 7 Parallel System & Dual Bus System
This chapter introduces the installation and operating of the parallel system and the installation of the dual bus system.
7.1 Overview
The 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 three or more modules are to be connected in parallel it is recommended that inductance should be inserted in
the static bypass line. This can be installed internal to the UPS as an option.
7.2 Installation Of Parallel System
The basic installation steps of parallel system are the same as those of UPS module. The following sections describe
the differences between the parallel system installation and UPS module installation.
7.2.1 Preliminary Check
Be sure that the parallel cable is selected, and that the modules are of the same rating and with the same software
and hardware release.
Warning
To achieve coordinated operation of the modules in the parallel system, it is required to configure each module separately using
background configuration software. This must be done by specialized service personnel of the manufacturer.
7.2.2 Cabinet Installation
Position the UPS modules and make connection as shown in Figure 7-1. The output distribution mode shown in
Figure 7-1 is recommended to facilitate maintenance and system testing.
