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2.1.5 Safety Ground
The safety ground busbar is located below the Maintenance Bypass circuit breaker or to the right of
the UPS Output breaker for 160-200KVA models as shown in Figure 4. 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.
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 5.4 - UPS Elec-
trical Characteristics and Table 9 for overload capacity.
When an external battery supply not made by Liebert is used, the customer must provide overcur-
rent protection for the battery circuit.
• 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 8.
2.1.7 Cabling Procedure
Once the equipment has been positioned and secured for operation, and the battery and ground col-
lars have been connected (see 2.1.4 - Cable Connections), connect the power cables as described
below. (Study the reference drawing in 6.0 - Installation Drawings.)
1. Verify that all incoming high and low voltage power circuits are de-energized and locked out or
tagged out before installing cables or making any electrical connections.
2. Remove the front protective cover to gain easier access to the connections busbars.
3. Connect the safety ground and bonding ground bus cables to the copper ground busbar located on
the bottom of the equipment below the power connections. All cabinets in the UPS system must be
connected to the user’s ground connection.
!
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 electromagnetic interference problems in systems.
NOTE
The ground busbar is easily accessible when the lower protective cover plate is removed.
!
CAUTION
The operations described in this section must be performed by authorized electricians or
qualified technical personnel. If you have any difficulties, contact your local Liebert
representative or Liebert Services.
NOTE
Hydraulic pressure pliers, combinative tools and piston ring pliers should be used to connect
AC wiring.
NOTE
The grounding bonding arrangement must comply with the National Electrical Code and all
applicable local codes.