Emerson Liebert NX 10-30kVA - Manual (Page 20)

Electrical Connections
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2.1.5 Safety Ground
The safety ground busbar is located below the neutral input and output busbars as shown in
Figure 5 below. The safety ground cable must be connected to the ground busbar and bonded to each
cabinet in the system.
All cabinets and cable conduit should be grounded in accordance with local regulations.
Figure 5 Ground and neutral busbar connections
2.1.6 Protective Devices
For safety, it is necessary to install circuit breakers in the input AC supply and external battery bat-
tery cabinets, external to the UPS system. Given that every installation has its own characteristics,
this section provides guidelines for qualified installation engineers with knowledge of operating prac-
tices, regulatory standards and the equipment to be installed.
UPS Rectifier and Bypass Input Supply
• Protection from excessive overcurrents and short circuits in power supply input
External overcurrent protection for the AC output circuit is to be provided. See 10.4 - UPS Elec-
trical Characteristics and Table 29 for overload capacity.
High-speed fuses and SCRs are used for internal battery circuit overcurrent protection. When an
external battery supply is used, overcurrent protection for the battery circuit is to be provided by
the customer.
• Dual Input
When wiring the UPS with dual inputs, the Rectifier input and the Bypass input must be pro-
tected separately. Size the breakers according to the input currents shown in Table 27.
System Output
When using an external distribution panel for load distribution, the output neutral and input neutral
must be separated at the input to the UPS.
!
WARNING
Failure to follow proper grounding procedures can result in electric shock hazard to personnel
or the risk of fire, should a ground fault occur.
NOTE
Proper grounding significantly reduces problems in systems caused by electromagnetic
interference.
NOTE
The ground and neutral busbars are easily accessible when the left protective cover plate is
removed. Cable connections should be made before a cabinet is attached to the left side of the
NX or before the UPS is placed where another obstruction, such as a wall, is against the NX’s
the left side.
OUTPUT
NEUTRAL
INPUT
NEUTRAL
Input neutral
busbar
Output neutral
busbar
Ground
busbar