Emerson 40-200KVA user manual Cable Connections, Safety Ground, Protective Devices

Electrical Connections

3.1.4Cable Connections

The rectifier input, bypass and output are easily accessible from the front of the unit for installation. All require lug type terminations. They are connected to busbars on the front side of the Liebert® NX™ and below the circuit breaker, as shown in Figure 3. These busbars are accessible when the front side panel is removed. Busbars to connect external batteries are accessible from the front of the UPS.

NOTE

External connection access requires removal of a protective panel on the lower front of the UPS.

NOTE

There is no battery fuse in the UPS; the battery cabinet must include a circuit breaker to cut off the current in case of short circuit. Refer to Table 8 for current ratings.

3.1.5Safety 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 3. 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.

! WARNING

Risk of electrical shock from ground fault. Can cause injury and death.

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.

3.1.6Protective Devices

For safety, it is necessary to install circuit breakers in the input AC supply and external battery battery 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 practices, 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 6.4 - UPS Electrical Characteristics and Table 9 for overload capacity.

When an external battery supply not made by Liebert is used, the customer must provide overcurrent protection for the battery circuit.

•Dual Input

When wiring the UPS with dual inputs, the Rectifier input and the Bypass input must be protected separately. Size the breakers according to the input currents shown in Table 8.

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