The following discussion describes the general
in the rear of the board. This results in a saving of
principles of a forward main IC switchboard, such as
space, which is most important aboard ship.
the one illustrated in figure 3-4. For a detailed
description of the main IC switchboard(s) and
The switchboard is a type 1, deck-mounted, front-
associated equipment installed on your ship, you
serviced, enclosed, box-type structure. The structure
should consult volume 5, part 1, of the Ship
is divided into panels, with each panel having a
Information Book for your ship and any related
hinged door. Lightweight items, such as switches,
meters, fuse holders of up to 60-ampere capacity, and
other equipment, are mounted on the front of the
hinged doors. The doors are hinged on the left-hand
Power Distribution Section
side and are provided with two "dog-type" latches on
the right-hand side and a door stop assembly.
The power distribution section of the
switchboard (panels 1 through 4) is supplied with
Terminal boards are mounted on the rear of each
power from as many sources as possible. The power
panel. Cables are terminated at the terminal boards
distribution section, in turn, supplies power from
on the inside of the panel. Wiring between the
its various buses to several IC and FC circuits.
terminal boards and the door-mounted equipment is
Power distribution by the switchboard of a
installed to ensure free-swinging of the doors without
particular ship depends on the requirements of the
interference from, or damage to, the wiring harness.
IC and FC systems installed.
The switchboard consists of a power distribution
PANEL 1.-- The 450-volt, 3-phase, 60-Hz bus
section and an ACO section, The power distribution
located in panel 1 is energized from one of three
section may be subdivided into various buses,
power sources (normal, alternate, or emergency).
depending on the individual ship requirements.
Power becomes available through the use of two
Figure 3-4 is an example of a front-service
mechanically interlocked switches and an automatic
switchboard that is currently installed aboard some
bus transfer (ABT) device located in panel 1. An
naval vessels. The distribution section consists of
indication of the power available is provided through
panels 1 through 4, while the ACO section consists of
the use of indicator lights connected via transformers
panels 5 and 6.
to each power source. On some of the newer ships in
Figure 3-4.--Front-service switchboard.