Separating Tied Systems; Load Transfers Between Ups Systems - Liebert Series 610 User Manual

2.2

Separating Tied Systems

The following sequence of operations describes the actions taken to separate two tied UPS systems.
Synchronize Systems
From the CONTINUOUS TIE CONTROL section, press the SYNCHRONIZE SYSTEMS button. The
button's light turns off to provide a visual indication of the operator's intention to separate the sys-
tems. The SYNCHRONIZE SYSTEMS button toggles between indicating the intention to parallel or
separate the two UPS systems.
Verifying Capacity
The Power-Tie logic checks the UPS systems and their loads to verify both systems have sufficient
capacity to maintain their loads once the systems are separated. If both UPS systems have sufficient
capacity, the OK TO OPEN TIE light turns on in the TIE CONTROLS section of the control panel.
OK to Open Tie
After the OK TO OPEN TIE light turns on, press the PUSH TO OPEN TIE AFTER OK button. The
tie breaker trips to separate the two UPS systems. Both systems automatically resynchronize to their
own bypass source; and all control loops between the systems separate.
2.3

Load Transfers Between UPS Systems

Functionally, load transfers are a continuous tie operation followed by an immediate selective separa-
tion of the systems. The following sequence of operations describes the actions taken to transfer a load
between UPS systems.
Selecting a System for Transfer
Select the system you want to receive the load, system 1 or system 2. Press the TRANSFER LOAD TO
button (for system 1 or system 2) on the LOAD TRANSFER CONTROL section of the control panel.
The system 1 or system 2 light turns on to indicate your selection.
You can cancel your selection by pressing the system button again. The button toggles between select
and deselect.
Synchronizing to the Bypass Source
The two UPS systems synchronize to the proper bypass source to perform the selected transfer. With
the line sync controls tied, the Continuous Power-Tie logic checks the inter-module sync signals for
coincidence. The Power-Tie logic ties the inter-module sync signals when coincidence occurs.
The SYNCHRONIZING light in the CONTROL STATUS section of the MIMIC panel turns on to let
the operator know synchronization is still in progress.
Checking for Phase, Voltage, and Capacity
The Power-Tie logic checks these UPS system parameters, phase, voltage, and capacity, to determine
when they have reached their proper limits. The OK TO TRANSFER LOAD (#) TO SYSTEM (#) indi-
cator turns on in the LOAD TRANSFER CONTROL section of the control panel on when these
parameters reach their proper limits.
Transferring the Load
After the OK TO TRANSFER LOAD (#) TO SYSTEM (#) light turns on, press the PUSH TO TRANS-
FER AFTER OK button.
The Power-Tie logic operates the proper circuit breakers in a make-before-break manner to transfer
the load.
Once the transfer starts, the TRANSFERRING light in the CONTROL STATUS section of the MIMIC
panel turns on indicating a transfer in progress. With the two UPS systems in parallel, the voltage
synchronization and power sharing loops become tied.
Transfer Complete
When transfer is complete, both systems automatically resynchronize to their own bypass source; and
all control loops between the systems separate.
13
Operation Description