can be paralleled between the units, that is, the same contact can be used for
several units’ signal input signaling. This concerns also the EPO signal.
5.6 Wiring parallel 91PS/93PS UPS systems
The outputs of multiple UPS systems can be connected in parallel. Up to 4 units
can be paralleled. The UPS static bypass power rating needs to be identical
among all the paralleled units. However, paralleled UPS cabinets can be housed
with different number of UPM power modules.
The outputs are paralleled to increase the load capacity of the power system
and for redundancy. The system is paralleled for (N+1) redundancy as long as
there is always one or more UPS online than required to support the load. The
system is paralleled for capacity if all UPSs in a system are required to support
the load.
Communication between the UPSs is required for system metering and mode
control. The system level communication and control are accomplished using a
Controller Area Network (CAN). A pull-chain signal in each UPS, connected to
the other UPSs in parallel and tied to the bypass status relay in each UPS, is
used for a secondary communication path. This arrangement ensures bypass
control even if the CAN bus is lost.
WARNING
Do not connect units equipped with an internal Maintenance Bypass Switch
(MBS) or internal transformers in parallel.
5.6.1
Power wiring overview
See Section
for the recommended cable and external fuse sizes and
installation practices.
Input feed
The input feed is defined as the power source connected to the UPS rectifier.
The feed to all UPS’s inputs must be derived from the same source.
Bypass feed
The bypass feed is defined as the power source connected to the UPS bypass.
The feed to all UPS’s bypass must be derived from the same source. The
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.
Eaton 91PS/93PS UPS 8–40 kW
User's and installation guide
©
Eaton Corporation plc 2018. All rights reserved.
Revision: 005
Document ID: P-164000493
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