due to maintenance, the other parallel-redundant UPS units will continue to provide uninterruptible power
to the critical load.
In a parallel system, the rated power of each UPS must be identical, and the rated power of each
equipment’s static bypass must also be identical. If the specified quantity is exceeded, contact your local
Eaton representative for a power distribution design.
Communication between the UPSs is required for system monitoring and module control. The system
level communication and control are accomplished using a Controller Area Network (CAN). A pull-chain
signal in each UPS ensures bypass control even if the CAN communication is lost.
WARNING
Do not use the internal Manual Bypass Switch (MBS) of a separate UPS in a
parallel system.
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For the recommended cable and external fuse sizes and installation practices, refer to Section 4.3.4UPS
system interface wiring preparations.
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The rectifier input 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.
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The bypass input 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 length of the shortest wire from the source to the UPS
must be a minimum of 95 % of the length of the longest wire.
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The neutrals of all the UPSs must be connected. The length of the shortest 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.
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The rectifier input and the bypass input are separate sources. The sources must share a common neutral.
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In case of a parallel use of the Eaton 93T UPS 15-80 kVA, both common battery and separate battery
configurations are supported for the cabinets. Refer to Section
5.3.2.1 Supported battery configurations for
more information on supported common battery configurations.
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In a parallel system, the electric line from the input of each UPS to the common point of the AC power
source must be as long as from the output of each UPS to the common point of the load. The wiring length
must meet the following regulations to make sure that the input resistance and the output resistance of
each UPS matches each other. The resistance error must be controlled within ±10 %. This is to make sure
EATON 93T USER’S AND INSTALLATION GUIDE 614-40270
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December 2023 www.eaton.eu 5566
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