Huawei USG6000 Series Hardware Manual page 410

HUAWEI USG6000 Series
Hardware Guide
Table A-18 Lightning protection and grounding requirements
Item
Civil
construction of
the equipment
room
AC power
system (TN-S
power supply
recommended)
Incoming power
cables
DC distribution
grounding
Issue 08 (2017-06-30)
Requirement
The equipment room should be built of reinforced concrete.
The equipment room should be equipped with lightning protection
devices, such as a lightning arrester.
The lightning protection ground for the equipment room (the grounding
of the lightning arrester) should share the same grounding conductor
with the protection ground of the equipment room.
A dedicated transformer should be used at a communications station.
Power cables that are connected to the communications station should
be buried with metal jackets or insulated jackets passing through steel
pipes. Both sides of the metal jackets or steel pipes are connected to the
nearest ground bar. The length of the buried power cables should be no
less than 15 meters.
The three phase lines at the low-voltage side of the AC transformer at
the communications station should each be installed with a closed zinc-
oxide lightning arrester for grounding. The enclosure of the
transformer, AC zero wire of the low-voltage side of the transformer,
and the metal outer protector of the power cable connected to the
transformer enclosure must be connected to the nearest grounding post.
AC and DC power cables should not be led into or out of the
communications station through overhead lines.
After low-voltage power cables are led into the equipment room, in the
AC voltage regulator and AC power distribution box (PDB), install a
lightning arrester for power cables and connect the lightning arrester to
the nearest grounding post.
If the equipment room is located in an urban area, the AC power system
of the equipment room should have a lightning protection unit with a
nominal discharge current of no less than 20 kA. If the equipment room
is located in a suburban area that is classified as a medium or high level
lightning zone, install a lightning protection unit with a nominal
discharge current of greater than 60 kA. If the equipment room is
located in a mountainous area that is classified as a high-level lightning
zone or in an isolated building in an urban area, install a lightning
protection unit with a nominal discharge current of greater than 100 kA.
The ground cable of the lightning arrester used for the power supply
must be shorter than one meter.
The DC working ground of the communications station (the positive
pole of the -48 V DC power supply or the negative pole of the 24 V DC
power supply) should be led in from the nearest indoor main earthing
conductor.
The device that supplies power to the communications station should
provide the DC working ground that connects from the collective
ground cable of the building (or from the protection ground bar in the
equipment room) to the power supply.
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