shore-power connection. Figure 9-11 shows a
shore-power plug. Personnel injury and equip-
FLEXIBLE CONNECTION
ment damage can be avoided when shore-power
ARC QUENCERS
cables and fittings are inspected before shore-
power connections are made.
Circuit Breakers
The purposes of a CB are to provide switching
operation, circuit protection, and circuit isolation.
Air CBs are used in SWBDs, switchgear
groups, and distribution panels. The types
installed on naval ships are ACB, AQB, AQB-A,
AQB-LF, NQB-A, ALB, and NLB. They are
called air CBs because the main current-carrying
contacts interrupt in air.
Circuit breakers are available in manually or
electrically operated types. Some types may be
operated both ways, while others are restricted to
one mode. They may or may not be provided with
protective functions. The differences and uses of
the various types of CBs are described in the
following sections.
ACB.--The ACB type of CB may be either
manual (local) closing or electrical (remote)
closing. It has an open metallic frame construc-
OVERCURRENT TRIP
tion mounted on a drawout mechanism and is
normally used where heavy load and high short-
Figure 9-12.--Type ACB circuit breaker.
circuit currents are available. Figure 9-12 shows
the external view of a type ACB circuit breaker.
Figure 9-11.--Shore-power plug.
9-12
