InfiNet Wireless R5000 Technical User Manual
Copyright © 2004-2006 by InfiNet Wireless Limited.
9
impulses are terminated on the IDU case by the winding shield, and further – on
the grounding contour. The data & power wires pickups on the top are
terminated via ODU protection scheme; on the bottom – via IDU protection
scheme (discharger and additional air gap). ODU and IDU grounding contours
are connected with 100 kOhm resistor, and that provides no static charge
accumulation on the ODU case if there are some problems with its connection to
the grounding contour.
Antenna pole, tower, ODU and lightning arrestor should be connected
to the first common grounding contour. Cable thickness should be no
less than 10AWG using corrosion-steady connectors. It is highly
recommended to entrust grounding contour development to the
skilled personnel. IDU should be grounded to the same contour as
customer LAN, having the second common grounding contour.
Antenna should be grounded
A special attention should be paid if antenna used is not DC-shorted. In this case
additional lightning arrestor should be used between the antenna and ODU.
Suggested grounding diagram is shown on the picture below.
Grounding when using IDU-5000-CPE
Antenna should be placed on the mast on the level that is at least 1 meter lower
than a mast’s top. In this case it is of big probability that the lightning strikes the
mast and not the antenna. The mast is to be grounded on the grounding contour
according to your local standards. When the lightning strikes the antenna, the
current goes through the coaxial cable which grounds ODU clamp with the mast
– the mast is grounded via the grounding contour. The direct lightning strike to
the STP service cable (ODU-IDU) is partially terminated on the grounded IDU
case. Partial termination means that the direct lightning strike will probably
destroy an STP cable. The service cable pickups from the electromagnetic
impulses are terminated on the IDU case by the winding shield, and further – on
the IDU grounding. IDU is grounded via a three-conductor power cord and a
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