Harris Maxiva ULX, Technical Manual

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10/6/10 888-2629-200 D-7
WARNING: Disconnect primary power prior to servicing.
Maxiva ULX COFDM Series
The transmitter building must be given extra protection to insure reliable equipment
operation. A low impedance safety ground system must be installed using 3 inch wide
copper strap hard soldered at all joints and connected to multiple ground rods located at
the perimeter of the building. The ground rods should be wet to make good connection
to the earth water table. All equipment cabinets within the building must be connected
to the ground straps for safety reasons.
Figure D-7 Basic Elements of a Properly Designed Antenna System
D.4 AC Service Protection
All incoming ac lines should have a choke connected in series to limit the high
frequency surges on the lines followed by a surge protector. The surge protector must be
connected to the building ground system by short direct connections, see Figure D-6.
A surge protector is a solid state device that has a high impedance until the voltage
across it reaches its rated clamping voltage, at which time its impedance suddenly
decreases. The protector will then conduct hundreds to thousands of amperes to ground.
All protectors are rated for maximum voltage and maximum surge energy. If the surge
energy exceeds rating of the device it will normally short and for this reason must be
fused so it will disconnect itself from the line being protected. When this happens all
protection is lost so some warning system must be used to tell the operators that a new
protector should be installed.
Speed is essential to protect equipment from current surges with rates of rise exceeding
10,000 amps per microsecond and pulses that last no longer than 100 microseconds.
Very short, low inductance ground straps are required to pass surges of this type.