3/6/08
888-2463-001
B-3
WARNING: Disconnect primary power prior to servicing.
Appendix B Surge, Lightning and
Diamond Series™
B.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.
Peripheral Equipment Grounds. All peripherals are supplied with a separate grounding
wire or strap. All branch circuit receptacles must permit connection to this ground. This
service ground must be connected through the branch circuit to a common grounding
electrode by the shortest and most direct path possible. This is a safety ground
connection, not a neutral.
Often, circuit common in test equipment is connected to power ground and chassis. In
these cases, isolated AC power must be provided from a separate isolation transformer
to avoid a ground loop.
B.2.3
DC Ground
DC grounds in the transmitter are connected to a ground bus, which in turn is routed to
a common cabinet ground and then connected to an earth ground. The use of separate
ground busses is a suggested method of isolation used to prevent cross-coupling of
signals. These ground buses are then routed to the cabinet ground and to earth ground.
