CHAPTER 3
AC POWER DISTRIBUTION SYSTEM
Almost every function performed aboard a naval
ship depends upon electric power for its accomplish-
ment From the launching of missiles against an
aggressive force to baking bread for lunch, electric
power is vital to a ship’s ability to accomplish its
mission.
The ship’s service electric plant is equipment that
takes the mechanical power of a prime mover and
converts it to electrical energy. The prime mover may
be driven by steam, gas turbine, diesel, or motor. The
mechanical energy of the prime mover is converted to
electrical energy in the ship’s service generators.
These generator sets supply power to the ship’s ac
power distribution system for further distribution to
the various electrical loads throughout the ship.
The ac power distribution system aboard ship
consists of the following:
Ac power plant.
Switchboards that distribute the power.
The equipment that consumes the power.
The power distribution system is comprised of the
following:
Ship’s service power distribution system.
Emergency power distribution system.
Casualty power distribution system.
ELECTRICAL DISTRIBUTION
SYSTEM
The electrical distribution system is the link
between the ship’s source of electrical power and the
ship’s electrical loads. Power is normally supplied
from the ship’s own generators but can be supplied
from an external source through the shore power
cables.
Most ac power distribution systems in naval ships
are 450-volt, three-phase, 60-Hertz, three- wire
systems.
Bus ties interconnect the ship’s service generator
and distribution switchboards so any switchboard can
be connected to feed power from the generators to one
or more of the other switchboards allowing the
generators to operate in parallel.
In large installations (fig. 3-1), power from the
generators goes through distribution switchboards or
Figure 3-1.-Power distribution in a large combatant ship.
3-1
