Emerson 480V, 60HZ user manual 2.1Power Cabling, 2.0ELECTRICAL CONNECTIONS, 2.1.1Cable Rating

Electrical Connections

2.0ELECTRICAL CONNECTIONS

The UPS requires both power and control cabling once it has been mechanically installed. All control cables must run separate from power cables in metal conduits or metal ducts that are electrically bonded to the metalwork of the cabinets to which they are connected.

! WARNING

Before connecting input power to the Liebert NX, ensure that you are aware of the location and operation of the overcurrent protection devices that connect the UPS input/bypass supply to the power distribution panel.

De-energize and lockout or tagout all incoming high- and low-voltage power circuits before installing cables or making any electrical connections.

2.1Power Cabling

2.1.1Cable Rating

The main factors affecting the choice and size of cable are voltage, current (also taking into account overcurrent), room temperature and conditions of installation of the cable.

The power cables of the system must be sized with respect to the following description:

•UPS input cables - The UPS input cables must be sized for the maximum input current, includ- ing the maximum battery recharge current, given in Table 8, with respect to the unit rating and the input AC voltage.

•UPS bypass and output cables - The bypass and output cables must be sized for the nominal output current, given in Table 8, with respect to the unit rating and the output AC voltage.

•Battery cables - When connecting an external battery cabinet, the battery cables must be sized for the battery discharge current at the end-of-discharge voltage, as given in Table 8, with respect to the unit rating.

NOTE

Table 8 gives nominal currents for determining the size of UPS power cables. Other important factors to consider include cable route length and coordination with protective devices.

The power cables can be sized to suit the UPS unit rating according to Table 8.

NOTE

When installing a Liebert NX with Softscale™ capability Liebert recommends sizing the input, bypass and output cabling for the UPS’s maximum rating. Properly sizing the cable will reduce the work required to upgrade the UPS.

Lug Size and Torque Requirements

Refer to Table 24 for lug size and torque requirements.

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