Harris Maxiva ULX COFDM Series, Technical Manual

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C-2 888-2629-200 10/6/10
WARNING: Disconnect primary power prior to servicing.
Maxiva ULX COFDM Series
susceptible to noise appearing on ground wires or adjacent wiring. Thus, all ground
wiring must be low in impedance as well as low in resistance, without splices, and as
direct as possible. Four basic grounds are required:
1.
AC ground
2.
DC ground
3.
Earth ground
4.
RF ground
C.2.1 Ground Wires
Ground wires should be at least as large as specified by the local electrical code. These
leads must be low impedance direct runs, as short as possible without splices. In
addition, ground conductors should be insulated to prevent intermittent or unwanted
grounding points.
Connection to the earth ground connection must be made with copper clamps which
have been chemically treated to resist corrosion. Care must be taken to prevent
inadvertent grounding of system cabinets by any means other than the ground wire.
Cabinets must be mounted on a support insulated from ground.
C.2.2 AC Ground
The suggested grounding method consists of two separately structured ground wires
which are physically separated from each other but terminate at earth ground. The green
ground wire from the AC power input must connect to the power panel and the ground
straps of the equipment cabinets.
The primary electrostatic shield of the isolation transformer, if used, connects to the AC
neutral wire (white) so that in the event of a transformer primary fault, fault current is
returned directly to the AC source rather than through a common ground system. The
AC neutral is connected to earth ground at the service entry.
Use of separate grounds prevents cross-coupling of power and signal currents as a result
of any impedance that may be common to the separate systems. It is especially
important in low-level systems that noise-producing and noise-sensitive circuits be
isolated from each other; separating the grounding paths is one step.
Noise Grounding Plate. Where excessive high-frequency noise on the AC ground is a
problem, a metal plate having an area of at least 10 square feet embedded in concrete
and connected to the AC ground will assist in noise suppression. The connection to AC
ground should be shorter than 5 feet, as direct as possible, and without splices. Local
wiring codes will dictate the minimum wire size to be used.