shortest length of power wire from the source to the UPS must be a minimum of
95% of the length of the longest wire.
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
28
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.
Parallel system cabling
Eaton 93PM UPS 30–200 kVA
User's and installation guide
©
Eaton Corporation plc 2017. All rights reserved. Revision: 005 Document ID: P-164000249 74 (126)
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