17
Lightning & Surge Protection
The product adopts multi-level anti-lightning and anti-surge technology integrated with gas discharge tube, power resistor
and TVS tube. The powerful lightning and surge protection barrier effectively avoids product damage caused by various
pulse signals with power below 4kV, including instantaneous lightning, surge and static. However, for complicated
outdoor environment, refer to instruction below for lightning and surge protection:
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The product features with dedicated earth wire, which must be firmly grounded. As for surveillance sites beyond the
effective protection scope, it’s necessary to erect independent lightening rods to protect the security devices. It’s
recommended to separate the lightning rod from the mounting pole, placing the rod on an independent pole, as shown
in the figure below. If the product has to be installed on the same pole or pedestal for lightning rod, there should be
strict insulation between the video cable BNC terminal, power cable, control cable and the standing pole of the
lightning rod.
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For suburb and rural areas, it’s recommended to adopt direct burial for the transmission cables. Overhead wiring is
prohibited, because it’s more likely to encounter lightning strike. Use shielded cables or thread the cables through metal
tubes for burial, thus to ensure the electric connection to the metal tube. In case it’s difficult to thread the cable through
the tube all the way, it’s acceptable to use tube-threaded cables only at both ends of the transmission line, yet the length
in burial should be no less than 15 meters. The cable sheath and the tube should be connected to the lightning -proof
grounding device.
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Additional high-power lightning-proof equipment and lightning rods should be installed for strong thunderstorm or
high induced voltage areas (such as high-voltage substation).
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The lightning protection and grounding for outdoor devices and wires should be designed in line with the actual
protection requirement, national standards and industrial standards.
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The system should perform equipotential grounding by streaming, shielding, clamping and earthing. The grounding
device must meet anti-interference and electric safety requirements. There should be no short-circuiting or hybrid
junction between the device and the strong grid. Make sure there’s a reliable grounding system, with grounding
resistance below 4
Ω
(below 10
Ω
for high soil resistivity regions). The cross-sectional area of the earthing conductor
should be no less than 25mm².
