After a sudden loss of power, having a manual
transfer of the power source will ensure all conditions
are met before energizing the equipment. (See figure
3-4.)
AUTOMATIC BUS TRANSFER (ABT)
SWITCHES
ABTs are used to provide two sources of power to
those loads that MUST be re-energized as soon as
possible after a sudden loss of normal power. Some
examples would be lighting in main engineering spaces,
ship’s steering motors and controls, motor-driven fuel
pumps, and lubricating oil pumps.
SHIP’S SERVICE SWITCHBOARDS
Aboard modem Navy vessels there are three distinct
groups or shipsets of distribution switchboards. A
shipset of main power distribution switchboards
consists of three groups, each group being comprised of
three units. Figures 3-5 to 3-7 show the switchboards
that comprise shipset 1S.
The units, physically separated and connected by
cables, form a switchgear group. This physical
separation of sections provides greater protection from
damage since it is less likely more than one unit can be
damaged by one hit in battle. It also provides a means
for removing a damaged section for repairs or
replacement.
Switchboards provide three distinct functions
aboard ship:
Distribution of 450-volt, 3-phase, 60-Hz power
Protection of distribution circuits
Control, monitoring, and protection of the
generator sets
Figure 3-4.-A pictorial view of the A-2 ABT.
3-4
