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Output
The neutrals of all the UPSs must be connected. The shortest length of wire from
the source to the UPS must be a minimum of 95% of the length of the longest
wire. The measurement is with respect to where the UPS’s outputs are tied.
Dual source
The input feed and bypass feed may be separate sources. The sources must
share a common neutral.
Battery connection
A separate battery shall be connected to each UPS, and the battery capacity for
each UPS must be identical. A common battery for all UPSs is not supported.
MOBs
Module Output Breakers (MOBs) allow the output of an UPS to be disconnected
from other UPSs and the system load for maintenance and service. Design
considerations assume that each UPS has a Module Output Breaker (MOB). The
breaker should also disconnect the neutral for improved safety during
maintenance.
The MOB must have a Form “C” auxiliary contact. The N.C contact is connected
to the corresponding UPS’s input used for signal input. The N.O. contact is used
to disconnect the bypass pull-chain when the MOB is open.
Figure 21: Principle
shows the principles of paralleled UPS systems
including MOBs and outputs from UPSs.
Mob override
Users without MOBs installed can simply leave the MOB signal input disabled.
The user should be aware that systems without MOB have limited maintenance
capability.
© Eaton Corporation plc 2020. All rights reserved.
Revision: 001
Document ID: P-164000956
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Eaton 93PM G2 UPS 50 – 360 kVA
User’s and Installation Guide