When a machine's vibration signature changes under its
standard operating conditions, an impending defect is
Distribution of the electrical power generated by a
starting to change the machine's mechanical condition.
ship's service gas turbine generator (SSGTG) or a ship's
Different defects will cause the vibration signature to
service diesel generator (SSDG) is accomplished by the
change in different ways. Analyzing these data will
switchboards. The operation and maintenance of the
provide a means of determining the source of the problem
60-Hz switchboards on all gas turbine-powered ships
as well as a warning of the problem itself.
are similar, though they will, of course, consist of some
items unique to a particular class of ship.
SAFETY AND HANDLING PROCEDURES
When it becomes necessary to disassemble and
Switchboards are constructed to withstand
reassemble a motor or generator, follow the procedure
high-impact shocks. Switchboard units consist of a
outlined in the manufacturer's technical manual. Use the
sturdy box frame built of angles and other structural
greatest care when handling the machines to prevent
shapes. This design provides enough strength for the
damage to any part. Remember, careless handling of
unit to resist breakage and distortion resulting from
parts will often cause more damage to a machine during
shock. It also provides enough stiffness to prevent
d i s a s s e m b l y or reassembly than the machine will
receive in years of general use.
All switchboards on gas turbine-powered ships are
All rotating elements of motors and generators are
of the dead-front construction. This means the
carefully balanced in the manufacturer's plant before
s w i t c h b o a r d units are protected by a sheet metal
assembly. This reduces noise, vibration, and wear of
enclosure. Figure 5-29 is an example of a dead-front
collector rings and brushes. It also improves the overall
electrical and mechanical performance of the machine.
The balance tends to become worse during normal
service because of vibration and shock. To maintain
optimum performance, remember to handle the rotating
parts carefully during disassembly and assembly.
ELECTRIC PLANT CONTROL SYSTEM
As you advance in the GS rating, your
r e s p o n s i b i l i t i e s for the maintenance, repair, and
operation of the electric plant control system will
increase. Your assigned tasks will include
t r o u b l e s h o o t i n g and repairing motor controllers,
motors, power panels, lighting circuits, and distribution
switchboards. It may appear that most of these tasks
would belong to the EM. However, on most gas turbine
ships, most of the electrical and electronic equipment
and systems in the main engine rooms and the generator
room is the responsibility of the GSEs.
The information in this section will provide you
with a basic knowledge of 60-hertz (Hz) switchboards,
t r a n s f o r m e r s , voltage regulators, and water wash
systems. After reading this section, you should be able
to identify basic maintenance procedures involved with
Figure 5-29.Dead front of a ship's service switchboard.