Riello UPS MASTER HE - Page 46

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Example of parallel operation
For the sake of simplicity, the instructions shown below refer to a system with three UPSs, but are equally valid
for more complex systems.
Let us assume that the signal cable is not damaged and that the UPSs are in the following state:
UPS STATUS
1) Normal operation, Master unit
2) Normal operation, Slave unit
3) Normal operation, Slave unit
A UPS PARALLEL CABLE type RJ45
1,2,3 Parallel-connected UPSs
If the signal cable between UPSs 1 and 3 is open (UPS
PARALLEL CABLE type RJ45).
UPS STATUS
1) Normal operation, Master unit with message “Parallel
signal cable fault” appears on the panel
2) Normal operation, Slave units with message “Parallel
signal cable fault” on the panel
3) Normal operation, Slave units with message “Parallel
signal cable fault” on the panel
In this situation the load is powered correctly. All the MASTER HE supply power to the load.
Let us assume that the signal cables between UPSs 1, 3 and 2,3 are opened.
UPS STATUS
1) Normal operation, Master unit with message “Parallel signal
cable fault” on the panel
2) Normal operation, Slave units with message “Parallel signal
cable fault” on the panel
3) Disconnected (TLI open, SCRs off), Slave units with message
“INTERNAL FAULT 10” on the panel
N.B.: In this situation the load is only powered correctly by
UPSs 1 and 2.
To restore the broken signal cable, first the UPS with the message “INTERNAL FAULT 10” on the panel has to be
shut down.
A
A
A
MHT / NBP MHT / NBP MHT / NBP
1 2 3
A
A
A
MHT / NBP MHT / NBP MHT / NBP
1 2 3
A
A
A
MHT / NBP MHT / NBP MHT / NBP
1 2 3