Emerson 115-208 Manuel D’Utilisation

For safety, it is necessary to install circuit breakers in the input AC supply 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 practices, regulatory standards and the 

equipment to be installed.

• Protection from excessive overcurrents and short circuits in power supply input

External overcurrent protection for the AC output circuit is to be provided. See 11.4 - UPS Elec-

trical Characteristics and Table 47 for overload capacity.
A breaker is 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.

When wiring the UPS with dual inputs but with a single input source, the Rectifier input and the 

Bypass input must be protected separately. Size the breakers according to the input currents 

shown in Table 41.

The Liebert APM’s main input and bypass input busbars are equipped with fuses (six locations; see 

Figure 33). The type is Bussman 170M4465, rated at 550A and 700V.

When using an external distribution panel for load distribution, the output neutral and input neutral 

must be separated at the input to the UPS.

Once the equipment has been positioned and secured for operation, and the battery and ground lugs 

have been connected (see 3.2.6 - 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 right side panel to gain easier access to the connections busbars.
3. Connect the safety ground and any easier bonding ground bus cables to the copper ground busbar 

located in the middle of the Liebert

®

 APM

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 below the Input and Bypass connections. All cabinets 

in the UPS system must be connected to the user’s ground connection.

4. Identify and make power connections with incoming cables according to Steps 5 through 8.

5. For common bypass and main inputs, connect the AC input supply cables to the UPS input 

terminals (A2-B2-C2-N1) and tighten the connections to 240lb-in. (27N-m) (M10 Bolt). Ensure 

correct phase rotation.

The operations described in this section must be performed by authorized electricians or 

qualified technical personnel. If you have any difficulties, contact your local Emerson 

representative or Liebert Services.

NOTE
Hydraulic pressure pliers, combinative tools and piston ring pliers should be used to connect 

NOTE
The grounding and neutral bonding arrangement must comply with the National Electrical 

NOTE
For common bypass and main inputs, the AC input cables must be connected to the bypass