Vertiv Liebert EXM - 3.2.6 Accessory Fuses and Back-Feed Breaker Wiring

Vertiv™ | Liebert® EXM
™
50-250kVA, 480V, 60Hz User Manual | 26
3.2.6 Accessory Fuses and Back-Feed Breaker Wiring
Figure 11 Fuse holders
Two fuse blocks provide power for the back-feed breakers (standard) and the Alber BDSUi
(optional). The accessory fuse holders are shown in Figure 24 and 26.
The back-feed breaker fuse block provides 480V nominal provided from the UPS output (L-L)
and the fuse is rated for 8 amps. Figure 13 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 480V must
be installed in the bypass input breaker and rectifier 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 input sources.
The Alber BDSUi fuse block provides 480V nominal from the UPS output (L-L) and the fuse is
rated at 8A. The Alber BDSUi power wiring is shown in SL-25656, the Liebert
®
EXM
™
Battery
Cabinet manual.
50-200K Frame
250K Frame
F2 F3 F4 F5 F6 F7 F8
F9
12
34
F9
12
34
F1
F2 F3 F4 F5 F6 F7 F8F1
F1-F2: Power from output U and V
for fan transformer
F3: For system fan 1#
F4: For system fan 2#
F5-F6: For external LBS fuse
F7-F8: Power for back-feed breakers
F9: Power for Alber BDSUi
F1-F2: Power from output U and V
for fan transformer
F3: For system fan 1#
F4: For system fan 2#
F5: For system fan 3#
F6: For system fan 4#
F7-F8: Power for back-feed breakers
F9: Power for BDSUi