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© 2004 Liebert Corporation
All rights reserved throughout the world. Specifications subject
to change without notice.
® Liebert is a registered trademark of Liebert Corporation. All
names referred to are trademarks or registered trademarks of
their respective owners.
SL-25246_REV1_04-11
Liebert Corporation
1050 Dearborn Drive
P.O. Box 29186
Columbus, OH 43229
Telephone: 1-800-877-9222
Facsimile: 1-614-841-6022
www.liebert.com
• Parallel system redundant UPS units: Set the
number of redundant UPS modules. This will
prevent the system from transferring to Bypass if
a fault condition occurs on the Master UPS in the
parallel system. For 1+1 systems, this must be set
to 1.
System Startup
1. Start each UPS normally as described in Liebert
NX installation manual, SL-25215.
2. Turn On the inverter of each UPS module one at
a time.
3. Apply the load after the last UPS module
transfers to inverter. The total load can be
determined through the LCD of either UPS.
4. Verify the load rate of each UPS module. If the
load rates are roughly the same, then the
parallel system may be assumed to be operating
normally.
Emergency Power Off (EPO)
The external emergency stop facility is identical to
that described for the single unit installation—that
an individual emergency stop button is provided for
each unit. Note that this is a Normally Open switch.
Figure 3 Connecting EPO push button
NOTE
The settings should be the same for all
modules within the parallel system, except
the UPS ID No.
NOTE
If one module will not transfer to Inverter
Mode long after its inverter is On, its output
connection may not be good or its output
phase rotation may not be coincident with
that of other modules. At this time, the LCD
for the UPS module will display “inverter
asynchronous” and the inverter indicator
will flash continuously. If either UPS
module makes abnormal noise after it
transfers to inverter, its parallel cables may
be incorrectly connected.
EPO-H
EPO-H
EPO-L
EPO-L
Monitor Board
Monitor Board
UPS1
UPS2
X2
X2
EPO
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