Vertiv
| Liebert
®
EXM
™
Battery Cabinet User Manual |
30
2.9.1
Accessory Fuses and Back-Feed Breaker Wiring
Two fuse blocks provide power for the back-feed breakers (standard) and the Alber
®
BDSUi
(optional). The fuse blocks are at the lower right of the I/O panel on the front of the Liebert EXM
UPS. See
Figure 13
for fuse-holder locations.
The back-feed breaker fuse block provides 120V nominal provided from the UPS output (L-N)
and the fuse is rated for 8 amps. The back-feed breaker wiring is on the bypass static switch
assembly.
The Liebert EXM UPS does not include internal back-feed protection. A shunt trip coil of 120V
must be installed in the bypass input breaker if the system does not include a Liebert Bypass
Cabinet. This is a safety feature and will prevent the UPS inverter from back-feeding the bypass
source.
The Alber BDSUi fuse block provides 208V nominal from the UPS output (L-N) and the fuse is
rated at 8A. See
Figure 12
for the Alber BDSUi power wiring.
Figure 13 Accessory fuses
2.10 Battery Protection
2.10.1 Battery Undervoltage Warning
Before the end of discharge, the Liebert EXM displays a low battery warning. After this warning,
the battery has the capacity for 5 minutes discharging with full load (default time). The Liebert
EXM can be user-configured to display this warning from 3 to 60 minutes before end-of-
discharge.
2.10.2 Battery End-of-Discharge (EOD) Protection
If the battery voltage is lower than the end-of-discharge voltage, the battery converter will be
shut down.
Alber
BDSUi
Fuse
Block
Back-Feed
Breaker
Fuse Block
