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Liebert
®
BDC
™
42
7.1.1 Bypass Mode
When the Liebert BDC is in Bypass mode, it provides an alternate path for power to the connected
equipment. Should the UPS need to be taken out of service for limited maintenance or repair, manual
activation of the bypass will cause an immediate transfer of the equipment from the UPS inverter to
the bypass source. In this mode, power will still be supplied to the UPS; however, the load is NOT
protected by the UPS.
7.2 Maintenance Mode
When the Liebert BDC is in Maintenance mode (MBB closed; BIB/MIB open), it provides an alternate
path for power to the connected equipment should the UPS need to be taken out of service for limited
maintenance or repair. In this mode of operation, no power is supplied to the UPS and the load is
NOT protected by the UPS.
7.3 Locating the Cabinet
This Liebert BDC may be mounted to the left of the UPS or installed as a stand-alone unit. In either
case, ensure that the unit is in a well-ventilated area and that there is clearance for access to the
switches and cable connections as required by national and local codes.
7.4 Cable Installation
7.4.1 Wiring Preparation
Be sure that the unit is not connected to any AC utility power source or UPS before installing any
wiring to this unit. This Liebert BDC should be installed by a qualified / certified electrician.
Removing the Cover Plates
Plates cover the input and output terminals on the front of the Liebert BDC. Remove these and keep
the screws and plates for reinstallation.
7.4.2 Power Cable Installation
Refer to Table 15 when selecting cables.
WARNING
Risk of electrical shock and arc flash. Can cause property damage, injury and death.
Read this section thoroughly before attempting to install wiring to this unit. Read and
comply with all warnings and cautions in this manual.
Table 15 Power cable size selection (Copper Wire Only)
Bus Type
Terminal
Main Input Bypass Input
OutputSingle Input Dual Input Dual Input
Liebert
®
NX
™
40kVA UPS 4 4 4 3
Liebert NX 60kVA UPS 1 1 2 2
Liebert NX 80kVA UPS 2/0 2/0 1/0 1/0
Liebert
®
NX
™
100kVA UPS 4/0 4/0 2/0 2/0
Liebert NX 120kVA UPS 250 250 4/0 4/0
Liebert NX 160kVA UPS 2-3/0 2-3/0 2-3/0 2-3/0
Liebert NX 200kVA UPS 2-4/0 2-4/0 2-4/0 2-4/0
Liebert NX 480V
Battery Cabinet DC Input Bus
225A 350A 600A —
4/0AWG 400kcmi 2-350kcmil —
NOTE
Transient and steady state earth leakage currents may occur when starting the equipment.
This should be taken into account when selecting ground current detection devices because
these will carry the earth leakage currents of both the UPS equipment and the load.