Page 2-2
Vector-LP Radio Beacon Transmitter Technical Instruction Manual
Issue 1.1
Section 2 Preparation for Use and Installation
2.2.2 Lightning Protection
Extremely high voltage and current
transients are produced when a lightning
strike occurs. These transients, which are
usually the most significant hazard to any
solid state transmitter, may be passed to
the transmitter through the wiring
connecting the transmitter to the power
source and the antenna system. All
practical precautions should be taken to
protect the transmitter from this
phenomenon. Refer to the
Lightning
Protection
section of Nautel’s
Recommendations for Transmitter Site
Preparation
booklet for specific protection
techniques. Installing Nautel’s interface
protection unit is highly recommended.
The following requirements are
considered to be essential and failure to
follow the site layout requirements may
void the transmitter warranty.
NOTE
The following paragraphs discuss
customer required connections to the
transmitter. Figure 2-2 is provided as an
aid for various customer interface
connections and should be referenced
while planning and installing these
connections.
2.2.3 Station Reference Ground
The site must contain a station reference
ground, as defined in Nautel’s
Recommendations for Transmitter Site
Preparation
booklet. This ground must
provide a continuous, low impedance path
to the earth. The transmitter cabinet's
designated station reference ground point,
the shield of the coaxial feed cable, and
the ground connection of the power
source's surge protection devices must be
connected directly to the station reference
ground using, as a minimum, 100 mm (4
inch) copper strap.
2.2.4 Ac Power Source
If an ac power source is used, all
conductors should be protected by bi-
directional surge protection devices that
are connected between each conductor
and the station reference ground. In
addition, the conductors, as a group,
should pass through a ferrite toroid. The
inductance formed by this toroid is
transparent to ac voltages, but presents
impedance to transients originating in the
power source. A surge protector panel,
containing suitably rated varistors, is
available from Nautel for this purpose. If
used, the surge protector panel should be
installed in close proximity to the station
reference ground.
2.2.4.1 Ac Wiring
The ac wiring for the transmitter should
not be smaller than 18 AWG, based on an
average ac input voltage of 200 V ac.
NOTE
Local electrical codes must be observed
when sizing cables. The ac power source
usually presents the lowest impedance
path to ground potential for a lightning
strike and will normally carry most of the
lightning induced current away from the
transmitter. When lightning hits the power
source, a significant amount of induced
current may flow towards the transmitter.
In this instance, the objective is to route
the current around the transmitter, instead
of through it, to the best ground available.
