switchgear groups to the load centers, through
distribution panels, and on to the loads. Distribution may
also be direct from the load centers to some loads.
On some large ships, such as aircraft carriers, a
system of zone control of the ship’s service and
emergency power distribution system is provided. The
system sets up several vertical zones that contain one or
mere load center switchboards supplied through bus
feeders from the ship’s service switchgear group. A load
center switchboard supplies power to the electrical loads
within the electrical zone in which it is located. Thus,
zone control is provided for all power within the
electrical zone. An emergency switchboard may supply
mere than one zone.
In small installations (fig. 3-2), the distribution
panels may or may not be fed directly from the generator
and distribution switchboards.The distribution panels
and load centers, if installed, are located centrally with
respect to the loads they feed. ‘his arrangement
simplifies the installation and requires less weight,
space, and equipment than if each load were connected
to a switchboard.
CIRCUIT MARKINGS
All distribution panels and bus transfer equipment
have cabinet information plates. These plates contain
the following information in the order listed
1. The name of the space, apparatus, or circuits
served.
2. The service (power, lighting, electronics) and
basic location number.
3.The supply feeder number.
Figure 3-2.-Power distribution in a gas-turbine powered DDG.
3-2
