Wiring Parallel 93Pr Ups Systems; Power Wiring Overview - Eaton 93PR Installation And Operation Manual

4.11. Wiring Parallel 93PR UPS Systems

The outputs of multiple 93PR UPS systems can be connected in parallel. A maximum of four 600kW
UPS frames can be connected in parallel and a maximum of two 1200kW UPS frame can be connected
in parallel. The UPS static bypass power rating needs to be identical among all paralleled units.
However, paralleled UPS cabinets can be housed with different number of UPM power modules. Above
four UPS in parallel requirement can ask help from Eaton technical solution team to customization
design.
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 is required between the UPSs for system metering and mode control. 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
Units with an internal MBS switch may not be connected in parallel.
4.11.1.

Power Wiring Overview

Refer to Section
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 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
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3.2.2 UPS System Power Wiring Preparation for recommended cable and
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