Emerson Liebert eXM - Accessory Fuses and Back-Feed Breaker Wiring

Electrical Connections—UPS
Liebert
®
eXM
™
22
3.2.7 Accessory Fuses and Back-Feed Breaker Wiring
Two fuse blocks provide power for the back-feed breakers (standard) and the 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 10
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. Figure 11 shows the back-feed breaker wiring, located on the bypass static
switch assembly.
The Liebert eXM 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 BDSUi fuse block provides 208V nominal from the UPS output (L-L) and the fuse is rated at 8A.
The BDSUi power wiring is shown in SL-25651, the Liebert eXM Battery Cabinet manual.
Figure 10 Accessory fuses
BDSUi
Fuse Block
(optional)
Back-Feed
Breaker
Fuse Block