Item
Requirements
Grounding of the
cabinet
l
All the devices including the surge protection device in the cabinet
must be connected in an equipotential manner. The ground cables
can be aggregated to the ground bar or surge protector socket first,
and then the ground bar or surge protector socket can be connected
to the ground.
l
The resistance between the device ground terminals and ground bar
cannot exceed 0.1 ohm.
l
The cabinet can be grounded using the protecting earthing (PE) wire
of the electrical network in the building, zinc-coated angle steel, or
the main steel bar of the building.
l
If the cabinet is grounded using the PE wire of the electrical
network, use a multimeter to test the grounding status. If the voltage
between the PE wire and neutral wire is lower than 5 V and the
voltage between the PE wire and live wire is about 220 V, the PE
wire is grounded well. If the tested AC voltages are not within the
ranges, the cabinet must be grounded in other ways.
l
The yellow-green ground cable contains multiple copper wires. The
cross-sectional area of the ground cable must be no less than 6 mm
2
(0.0093 in.
2
) and the length cannot exceed 3 m (9.84 ft.).
l
Ground cables cannot be twisted with signal cables.
l
Antirust and anticorrosion measures must be taken on the ground
terminals.
l
The fiber reinforcing rib can be directly connected to the ground bar
of the cabinet. Before wrapping the reinforcing rib with insulation
tape, cut a 0.5 m (1.64 ft.) segment from the reinforcing rib. Wrap
the reinforcing rib with at least five layers of insulation tape. Keep
the reinforcing rib at least 5 cm (1.969 in.) from the cabinet surface.
5.2.2 Requirements for Power Supply
Requirements for AC Power Supply
An AC power supply system consists of power mains, uninterruptible power supplies (UPSs),
and self-supplied electric generators. In addition to meeting the requirements of the server
load, the AC power supply must have a simple connection line, safe operation, flexible
scheduling, and easy maintenance.
The low-voltage power supply should be 3-phase, 5-wire mode or monophase 3-wire mode.
This AC power supply should be 110 V/220 V, with a frequency of 50 Hz.
The UPS should supply the same power and operate at the same phase as the power mains.
The switching time between the UPS and mains should be less than 10 ms; otherwise, the
networking devices will reboot or reset.
For power distribution capacity in the equipment room, both the working current and fault
current of the devices should be considered. Ensure that independent AC power supplies
R250D-E
Hardware Installation and Maintenance Guide
5 Appendix
Issue 01 (2016-09-30)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
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