Terrasat IBUC 3, Operation Manual

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3-6
|
IBUC
3
, IBUC
3 G
Operations Manual: Installation
Engineered to Endure
• AC
The best way to protect the equipment is to have two protectors. The first is the
power mains protector that is mounted directly across the mains in the breaker box.
The second should be mounted or grounded directly at the base or hub of the
antenna or at the 19 - in. rack.
• Data and Control Lines
The I/O lines can deliver surge current to the equipment and should also be
protected.
• Electrical Grounding
Grounding of the IBUC
3
or IBUC
3
G
and PSUI units is recommended to prevent
possible damage from lightning or other induced electrical surges. Terrasat
recommends using 3/0 or 4/0 AWG stranded copper wire for bonding the IBUC
and the PSUI to the earth ground (or grounding rod), using the most direct or
shortest route.
Antenna Recommendations
Most antenna masts are encased in concrete. Typically, the mast pipe is submerged in
a 4 ft to 5 ft (1.22m to 1.53m) deep augered hole. This provides a good Ufer ground.
A Ufer ground encases grounding connectors in concrete. Concrete absorbs moisture
quickly and loses that moisture slowly—as much 15 to 30 days after rain or snow
melt). The mineral properties of concrete and their natural pH mean that concrete has a
supply of ions to conduct current. The soil around concrete becomes “doped” by the
concrete and, as a result, the pH of the soil rises. The moisture in the concrete in
combination with the “doped” soil make a good connector of electrical energy. The
concrete’s large volume and area of contact with the surrounding soil allow a good
transfer to the ground. In the concrete base, a Ufer ground can be established by
running #4 gauge solid wire or rebar and connecting to the base of the pedestal with
pigtails.
The Ufer ground is only one step in proper grounding. The Ufer ground should be
augmented with coupled pairs of 10 ft (3.05m) ground rods placed 20 ft (6.1m) into
the ground, spaced 20 ft (6.1m) apart. The first rod should be placed close to the
antenna. The second rod should be placed towards the equipment enclosure. A #2
gauge wire should connect the rods and antenna mount. A ground rod should be placed
at the equipment enclosure, as well. If it is virtually impossible to install the ground
rods, then radials are needed. This can be accomplished by laying 10 or more of 1½ - in.
(3.81cm) copper strap at least 50 ft (15.24m) long in a radial fashion around the
antenna base. The straps should be buried, if possible. The hub must be interconnected
to the utility ground. The ground configuration can vary from one location to another.
It is best to measure soil conductivity and design a 5 Ω or less ground system. To
protect the system from a direct strike, a lightning rod placed 2 ft (61cm) higher than
the highest point of the dish should be interconnected to the Ufer ground with #2
gauge copper wire.