Harris ZX10, Техническое руководство

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2-8 888-2595-001 12/20/11
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WARNING: Disconnect primary power prior to servicing.
Section 2 Installation
ZX Series
or outside “at the pole” (as dictated by local norms), thus allowing any fault current to
safely return to the power source.
The AC safety ground connection is made automatically for the exciter and ZX
amplifier via the green/yellow wire on the third prong of the AC input cord. When the
exciter and amplifier chassis are connected directly to a user-supplied outlet box or
distribution panel, the green-yellow wire from the AC input cord(s) must terminate at
the PE terminal at the AC mains source.
In the case of a Harris-supplied AC distribution chassis, the green/yellow earth wire
from the incoming AC mains service terminates at the PE terminal of the AC
distribution chassis (ground symbol inside circle). The individual subassemblies
making up the transmitter connect via the green/yellow wire of their mains cords to the
same PE terminal on the AC distribution chassis.
When present, a rack buss-bar will also connect to the PE terminal. Individual panels
making up the rack cabinet without a solid, permanent connection back to the PE
terminal that might be exposed to unsafe voltages (e.g. doors on hinges) will connect to
the PE terminal via a wire jumper connection to the buss-bar.
The RF earth ground prevents damage to the equipment during lightning-induced
transients and reduces RF interference to low level circuits in general. An RF ground
strap/wire attachment point is located at the rear of the ZX amplifier and exciter chassis.
This connection is suitable for use in a single point grounding system, with the ground
strap attached to the equipment rack and the rack, in turn, to a common grounding plate.
NOTE:
Observe this important distinction: The AC safety ground ensures that energy
originating at the AC mains source is always safely returned to the AC mains
source (i.e. prevents electrocution), whereas the RF earth ground ensures that
energy “originating in the earth,” such as lightning, safely returns to the earth.
Confusion may arise in some cases because the AC safety and RF earth ground
circuits may share the same conductor or connection point(s) in some scenarios.
To prevent confusion, some sources refer to the AC safety ground as “bonding”
and the RF earth ground as “earthing.”
2.8.1 Overview of RF Grounding Practices
The importance of a good RF grounding system and lightning protection cannot be
overemphasized for reasons of personnel safety, protection of the equipment, and
equipment performance. The following is only a brief overview.