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 Table 2-1
Facility Ground System: Purposes, Requirements, and Design Factors
Purpose
Subsystem
Requirements
Design Factors
Lightning Protection
Dissipate lightning energy in
Multiple connections to earth electrode
Lightning protection subsystem must
earth.
subsystem, high peak power transfer
be sized to dissipate energy in
capability, low impulse impedance to
a lightning pulse (worst case) without
minimize magnitude of transient potentials.
producing hazardous voltages or
damage to itself.
Fault Protection
Provide fault current path
Low resistance in the return path for
Resistance should be low enough
to operate equipment break-
fault current, maintain voltage of equip-
to permit operation of facility
ers, blow fuses, etc.
ment enclosures near earth potential.
over-current devices when faults
occur.
Signal Reference
Reduce noise in signal cir-
Establish reference potential for sign-
tection system currents normally
cults, provide leakage path
al voltages, provide sink for static
should not flow in the signal reference
for static charges, establish
charge.
voltage reference.
network; earth connection should not
degrade signal quality.
Provides link for lightning
Installed around periphery of
Earth Electrode
Law resistance path to earth.
protection, fault protection and
building or tower to be protected.
signal reference subsystems to earth.
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