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Outdoor Equipment: the need for surge (lightning) protection
Apart from the need to provide good grounding for safety, outdoor equipment
is subject to more environmental hazards than is indoor equipment. Radio
communication equipment, with antennas mounted well above ground level,
have conductive parts exposed to lightning.
Safety needs are met by grounding practices and protection needs are met by a
combination of grounding and protective devices. Many protective devices are
available:
•
air terminals,
•
solid state OVPs,
•
filters,
•
zeners,
•
MoVs,
•
isolators
•
capacitors,
•
resistors,
•
QWS and more.
The application of these devices is beyond the scope of this document. The
equipment designer needs to consider both the protection requirements and
the geographic region where the equipment is installed.
Grounding and Lightning Protection
In general, all exposed metallic equipment must be grounded. Besides the
need for lightning protection, it is desirable to conduct induced current to
ground through as low a resistance as possible, along as short a path as
possible.
In practice this means multiple ground connections and multiple conductors.
Figure 2-2 shows a typical rooftop installation of Reunion customer premise
equipment. Figure 2-3 shows a typical rooftop installation of Reunion base
station transceiver (BTR).
The radio equipment should, where possible, be grounded through the ground
lug using a 6AWG bonding wire to the building common bonding network.
Alternatively, the equipment can be grounded through the mounting bracket.
Provision must be made to prevent corrosion on the metallic contact surfaces.
Similarly, the installer shall ensure that there is a good metallic connection to
the building CBN.
If a common mounting plate is used for the two redundant BTRs and the radio
power extractor (RPE), the installer shall insure that ground continuity to the
CBN is maintained and corrosion protection is applied. The common
Grounding and Surge Protection 2-3
Reunion CTR 28 GHz Installation Guide
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