just because you are a GSM, you are not exempt from
3. Withdraw the borescope retaining the axial
learning about the operations of the generators. In this
circumferential orientation, look at the angle relation-
section, we will give you a brief explanation of the
ship, and visually assess the comparison of the actual to
operations of the generators and their accessories. The
the marked defect (from the installed blade to the
primary goal of this section, however, will be to tell you
external sample).
about your responsibilities concerning maintenance,
4. Correct the depiction until you are satisfied that
troubleshooting deficiencies, and repair of these
the two images compare.
generators, their support systems, and reduction gears.
5. Measure the marked defect.
NORMAL OPERATIONS OF
Regardless of the method you use to determine the
DIFFERENT MODELS
size of the damaged area, you must always document
your conclusions.
The primary function of all generators installed on
DOCUMENTATION. At the completion of any
any gas turbine-powered ship is to provide stable 60-or
borescoping procedure or inspection, you must always
400-Hz electrical power for distribution throughout the
document your observations so that an accurate
ship. As we have explained throughout this chapter, gas
evaluation of engine condition can be made. Remember,
turbine ships use a variety of prime movers to rotate
the decision to continue engine operation or to remove
these generators.
the engine from service will be made according to
documented engine conditions.
At the time this book was written, there were six
d i f f e r e n t models of generators used on gas
In performing your routine maintenance,
turbine-powered ships. Of theses six models, four
inspection, and repair responsibilities, you may
provide stable 60Hz, 450-volt ac power to their
frequently discover component deterioration that will be
respective ships. In the following paragraphs, let's take
within the acceptable limits. This is why it is so
a closer look at these four models.
important that you keep an accurate record of the degree
of deterioration. You should consult the applicable
equipment and component records before you begin an
CG-, DD-, DDG-51, DDG-993, and
inspection. After your inspection, you should carefully
FFG-Class Ships
document the extent or degree of deterioration and
damage to each affected area. When subsequent
All of the four generator models that produce the
inspections must be performed, other inspectors must be
same 60-Hz, 450-volt ac power arc installed on the CG-,
able to use your documentation in the same way you
DD-, DDG-51, DDG-993, and FFG-class ships. Among
were able to use the existing documentation before
the four generator models installed on these ships, the
beginning your own inspections. Before any inspection,
main difference is in their kW outputs.
the records and documentation concerning the condition
KILOWATT OUTPUTS. On the FFG-class
of each component should be consulted before the
ships, the generators have a 1,000 kW output. On the
inspection is started so areas of concern can be
DD- and DDG-993 class ships, the generators are rated
emphasized and not overlooked. This will allow a
at 2,000 kW. On the CG- and DDG-51 class ships, the
subsequent inspection to determine how rapidly the
generators are rated at 2,500 kW.
component is failing. With experience and good
documentation, it is often possible to make estimates of
ACCESSORIES. Among these four generator
the remaining life of a component.
models, another difference you will find is in the
accessories that are installed to support these units.
We have now discussed your maintenance
responsibilities for the GTE. In the following sections,
REDUCTION GEAR ASSEMBLIES. Although
we will take a look at some of your responsibilities for
all of these generators receive the transmission of power
other areas of the electrical generating plant.
(rotation) from their prime movers through some form
of reduction gear, the reduction gear assembly will be
different, depending on the class of ship. On the
GENERATORS AND REDUCTION
DD-class ships, for example, the generators need only
1,800 rpm to produce the required frequency, voltage,
As a GSM2, you will need to become more and
and power output. Remember, 1,800 rpm is significantly
more familiar with the total electrical plant. Remember,
lower than the turbine's speed of 13,821 rpm.
