that there is current sharing between the UPSs in a parallel system. It is recommended that the combined
length of the input and output cables in a parallel system is greater than 10 meters.
If only two UPS units are connected in parallel, the above requirements are not mandatory, but future
upgrades might be affected if the requirements are not satisfied.
Make sure that the static bypass input of each UPS in a parallel system is connected to the same feeder,
such as an external bypass circuit breaker. If the rectifier input of each UPS in a parallel system is a
separate power source, consult your local Eaton representative to make sure that the power is distributed
correctly.
Figure 32. Principle of parallel UPS system wiring
1 UPS 1 A Bypass inputs to UPSs
2 UPS 2 B Rectifier inputs to UPSs
3 UPS 3 C Outputs from UPSs
4 UPS 4 D Load
NOTE: For correct operation, all cables marked as A must be equal in length, and all cables marked as C
must be equal in length.
55..55..22 CCoonnttrrooll ssiiggnnaallss oovveerrvviieeww
Two control signals, External CAN Network (ECAN) and Bypass Pull-Chain, are required for an external
parallel system. Both of these control signals are employed for the purpose of fault tolerance. If one of
them is disconnected, the system raises an alarm and continues normal operation.
In the 93T UPS (15–80 kVA), the ECAN, Bypass Pull-Chain, and the external parallel control signal are
connected to the external parallel ports. For the location of the ports, refer to Figure
24: Communication
interfaces.
EExxtteerrnnaall CCAANN ((EECCAANN))
ECAN provides a means for communication between the UPS units in a parallel system. The system
continues to share current and protect the load even when this network fails.
EATON 93T USER’S AND INSTALLATION GUIDE 614-40270
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December 2023 www.eaton.eu 5577
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