Emerson Liebert NX 50 and 60 Hz - Manual (Page 89)

Operation
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6.2 Multi Module UPS—1+N
Multi-module UPS are formed by several “single unit” UPS modules to constitute “1+N”system where
groups of one or more, up to six, single units operate together for the purpose of providing additional
power or reliability or both. The load is equally shared between any paralleled UPS.
Figure 64 1+N multi-module UPS with external maintenance bypass switch
Further, single unit or 1+N groups may be configured as “distributed redundant” systems with inde-
pendent outputs that nevertheless are synchronised through a Load Bus Synchroniser (LBS) so that
critical loads can be seamlessly transferred from one system to another. See 6.3 - Modes of Opera-
tion for more information.
6.2.1 Features of NX Multi-Module UPS Configurations
1. The hardware and firmware of single module UPS units is completely compatible with the
requirements of a multi-module system. Multi-module configuration is achieved merely through
settings in configuration software and control cables.
2. Parallel control cables are connected in a ring, providing both performance and redundancy.
Dual-bus control cables are connected between any two UPS modules of each bus. The intelligent
paralleling logic provides the user with maximum flexibility. For example, shutting down or
starting up UPS modules in a parallel system can be done in any sequence. Transfers between
Normal and Bypass modes of operation are synchronised and self –recovering e.g. following
overloads and their clearance.
3. The total load of the multi-module system can be queried from each module’s LCD.
Distribution Cabinet
Qout UPS2 Qout UPS1
Qout all UPS
UPS3
SUPPLIED BY OTHERS
L1, L2, L3, N L1, L2, L3, N L1, L2, L3, N
UPS3 OUTPUT UPS2 OUTPUT UPS1 OUTPUT
L1, L2, L3, N L1, L2, L3, N L1, L2, L3, N
Qin Ext Byp
Qin UPS3 Qin UPS2 Qin UPS1
Q1 Q1
CHARGER
UPS2
INPUT MAINS SUPPLY
BYPASS MAINS SUPPLY
L1, L2, L3, N L1, L2, L3, N
INPUT MAINS SUPPLY
BYPASS MAINS SUPPLY
L1, L2, L3, N
INPUT MAINS SUPPLY
RECTIFER
INVERTER
Q5
Q3
Q2
Qout UPS3
Qout
BYP
CHARGER
RECTIFER
INVERTER
Q5
Q3
Q2
UPS1
Q1
CHARGER
RECTIFER
INVERTER
Q5
Q3
Q2