EXS
User Manual 10H52267UM60 - Rev. 1 - 09/2018
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Chapter 6
Parallel System and LBS System
This section provides information about installing parallel and LBS systems.
6.1
General
The UPS parallel system consists of up to four single UPS of the same model. The parallel system does not require a
centralised bypass device. The bypass sections of the individual UPS modules 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 load sharing, synchronizing and bypass switching. The control signals
are connected by means of 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, we recommend installing the inductor on the bypass line.
This component may be installed internally to the UPS as an option.
6.2
Requirements
A UPS system consisting of multiple, parallel-connected UPS units is equivalent to a large UPS system. However, it also
provides increased system reliability. To ensure equal utilization of all UPS units and compliance with relevant wiring
regulations, the following requirements must be met:
1. Each individual UPS unit must have the same rating.
2. The bypass input power and the main input power lines must be connected to the same neutral line input terminal.
3. If it is necessary to install a residual current detector (RCD), it must be set-up correctly and installed upstream of the
neutral line input terminal, or it must monitor the protective earth current of the system. Refer to 'Warning: high leakage
current' in the Safety Precautions, which appear before the Contents section of this manual.
4. The outputs of all individual UPS units must be connected to the same output bus.
6.3
System Installation Procedures
The basic installation procedure of a parallel system consisting two or more UPS modules is the same as that for a
single module system. This section only covers the installation procedures that are specific to the parallel system.
When installing a parallel UPS system, follow the installation procedures for a single UPS module, with the additional
requirements detailed in this section.
Warning
In order to ensure that the parallel system operates normally, the Vertiv service personnel must carry out the CAN resistance
procedure. Failure to do so could result in system faults.
6.3.1
Preliminary Checks
Make sure that correct parallel cable option has been selected, and that the module ratings, model, and software and
hardware releases are consistent and compatible.
Warning
To guarantee coordinated operation of the modules in the parallel system, each module must be configured separately using the
VERTIV setting software. This must be done by Vertiv service personnel.
6.3.2
Cabinet Installation
Place the UPS modules side by side and interconnect them as shown in Figure 6-1. The output distribution mode (QE1,
QE2 must be configured) shown in Figure 6-1 is recommended to facilitate maintenance and system testing.
