RC Systems ViewSmart 1600+, Operation Manual

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UM-1097
Revision B 128
Avoid installing coax cables together in long parallel paths. Leakage from one cable to another has a similar
effect as mounting an antenna near another antenna.
Surge Protection and Grounding
Voltage surges can enter the WaveNet System via the antenna connections, power supply connections,
connections to other equipment and even the earth or ground connection. Surges are electrical energy
following a path to earth and the best protection is achieved by draining the surge energy to earth via an
alternate path. Wireless devices need to have a solid connection to earth via a ground stake or ground
grid if the soil has poor conductivity. Solid connection means a large capacity conductor (not a small wire)
with no coils or sharp bends. All other devices connected to the WLR need to be grounded to the same
ground point. There can be significant resistance between different ground points leading to very large
voltage differences during lightning activity. As many wireless units are damaged by earth potential surges
due to incorrect grounding as direct surge voltage.
It is very difficult to protect against direct lightning strikes but the probability of a direct strike at any one
location is very small. Unfortunately, power line surges and electromagnetic energy in the air can induce
high voltage surges from lightning activity several miles away.
Antenna Grounding
Electromagnetic energy in the air will be drained to ground via any and every earth path. An earth path
exists between the antenna and the WaveNet, and to protect against damage this earth path current must
be kept as small as possible. This is achieved by providing better alternate earth paths. It is important to
ground the antenna to the same ground point as the WaveNet. Antennas are normally mounted to a metal
bracket which should be grounded to the WaveNet earth connection. Surge energy induced into the
antenna will be drained first by the mount’s ground connection, second by the outside shield of the coax
cable to the ground connection on the radio and third by the internal conductor of the coax cable via the
radio electronics. This third earth path causes damage unless the other two paths provide a better earth
connection allowing surge energy to bypass the electronics.
When an antenna is located outside of a building and outside of an industrial plant environment, external
coax surge diverters are recommended to further minimize the effect of surge current in the inner
conductor of the coax cable.
Coax surge diverters have gas-discharge element which breaks down in the presence of high surge voltage
and diverts any current directly to a ground connection. A surge diverter is not normally required when
the antenna is within a plant or factory environment, as the plant steelwork provides multiple parallel
ground paths and good earth grounding will provide adequate protection without a surge diverter.