remaining bus ties are not energized. (See fig. 3-7, view
Overpower protection will cause load shedding of
preselected nonvital and semivital loads. If automatic
A.) The EPCC configuration status logic can identify
load shedding does not reduce the load sufficiently,
any split-plant configuration by monitoring the open
additional loads will have to be removed manually.
and close status of the generator and bus tie breakers.
STANDARD PARALLEL-PLANT CONFIGU-
R A T I O N S . -- In parallel-plant operations, two
generators are on line and paralleled. Additionally, all
bus tie breakers are closed to connect the three main
Load shedding is a process by which loads are
switchboards in a loop system. Configuration status
removed from the electrical bus to prevent overloading
logic at the EPCC identifies the on-line generators for
o f the on-line generators. Load shedding can be
auto recovery logic. (See fig. 3-7, view B.)
accomplished manually or automatically. On the CG-47
NONSTANDARD PLANT CONFIGURA-
class ships, load shedding is completely independent of
T I O N S . -- The open loop paralleled generator
configurations, as shown in view C of figure 3-7,
Manual load shedding can be accomplished by
energize all three switchboards with two generators.
depressing the LOAD SHED push-button indicator on
These configurations are operator selected or are the
the EPCC. This switch transfers +28 volt dc power to a
result of a failure. All electrical distribution functions
have these configurations, but automatic recovery
A u t o m a t i c load shedding is initiated by any
capability is not available.
overpower sensor circuit in one of the switchboards. The
EMERGENCY CONFIGURATIONS.-- Normal
sensor circuit energizes a self-contained relay whose
plant operation requires two generators in parallel or
c o n t a c t s are in parallel with the LOAD SHED
split-plant configurations. In an emergency with two
ACTIVATED pushbutton at the EPCC. Closure of these
generators inoperative, one generator must energize the
contacts energizes the same load shedding control relay
t h r e e switchboards. (See view D in fig. 3-7.)
as in manual load shedding.
Figure 3-7.--Electric plant configurations.