Vertiv Liebert EXM2 - Protection Ground; External Protective Device

4.1.8 Protection Ground
The protective earth cable is reliably connected to the PE input terminal (see Figure 4.2 on page40) via the fixing bolt. All the
cabinets and cable troughs shall be grounded according to the local regulations. The grounding wires shall be tied up reliably
to prevent the loosening of the grounding wire tightening screws when the grounding wires are pulled.
W A RN IN G!
Failure to ground as required m ay cause EM I, electric shock or fire risk.
4.1.9 External Protective Device
To ensure the safety, it is necessary to install external circuit breaker for the input and battery of the UPS. Because of the
difference of the specific installations, this section only provides general practical information for the installation engineer.
The qualified installation engineer should have the knowledge of the local wiring regulations on the equipment to be installed.
Input power supply of rectifier and bypass
1. Input overcurrent and short circuit protection
Install suitable protective devices in the distribution line of the incoming mains supply. The protective devices should provide
functions such as the overcurrent protection, short circuit protection, isolation protection and tripping upon backfeed. When
selecting the protective devices, consider the power cable current-carrying capacity, system overload capacity (see Table
12.6 on page185 and Table 12.7 on page186) and the short circuit capability of the upstream power distribution.
2. Split bypass configuration
If the UPS adopts split bypass configuration, independent protective device shall be installed respectively on the rectifier
input and bypass input distribution lines.
N O T E: T he rectifier in p u t and bypass in p u t m ust u se the sam e neutral line.
N O T E: For IT grid system , 4-pole protective com ponents must be installed for the U PS external input
pow er distribution.
3. Ground fault protection
If the pre-stage input power supply has an RCD, the transient state and steady state ground leakage current upon the startup
of the UPS shall be considered.
4 Electrical Installation
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Vertiv™ Liebert® EXM2 UPS User Manual