alarm. If the oil pressure is sufficient, then a
Electrical Tests. Most of the tests will be electrical.
blockage in the system maybe the cause of the
As a GSM, you will be primarily concerned with
problem. In this case, because the system's oil
assisting the GSEs. Even then, most of the tests will be
minor and easily accomplished. Primarily, these tests
pressure is measured after the filter, you can
will consist of voltage and resistance readings on the
eliminate the filter as the problem.
generator, lube oil pressure and air temperature switch
2. Check the sump level. If the level is low, inspect
testing, and testing of the associated alarms.
for leakage or an improperly positioned drain
Generator Load Testing. The last test we will
valve and then add oil if the loss can be
discuss is generator load testing. Load testing is
explained. If the oil level is satisfactory, you
normally required and accomplished after major repairs
must trace the system and identify the faulty
have been made to the generator. This procedure is
component. Some of the likely causes of the
usually accomplished by a repair activity because of the
problem could include;
special equipment (salt box) required and the magnitude
a. A faulty pump. Check for a faulty relief
of the job.
valve or sheared drive.
Inspections. Inspections, on the other hand, are
b. A faulty bypass valve (DD- and DDG-993
primarily accomplished as part of the watch routine as
class ships).
well as during maintenance. As a watch stander, you
will continually inspect the generator for oil leaks and
c. A blocked cooler (DDG-51 class ships).
overall operating efficiency. Depending on the location
High Oil or Bearing Temperature. In many cases,
of the leak, an oil leak can be extremely detrimental to
a high oil or bearing temperature can accompany or
the operation of any generator. For this reason, you will
cause the other problem to occur. For example, if the oil
normally inspect the oil system for leakage inside as
temperature becomes too high, the bearing temperatures
well as outside the generator. You will perform this
will also increase. Also, if a bearing becomes
inspection by looking through an inspection window
overheated, the excess heat will be transferred to the oil.
(where provided) on the end of the generator.
If either one of these problems should occur, take the
If an oil system develops a leak on the inside of the
following steps:
generator, several problems can result. The first and
1. Verify the oil pressure and flow. Low oil
probably the most serious problem is a fire. Other
problems include the abnormal or rapid wearing of the
to overheat. If either of these symptoms is the probable
generator brushes (if installed) and the lowering of the
cause, refer to the preceding section on low or no oil
generator's overall insulation resistance. Ultimately,
these other problems can also cause a fire if they are left
flow.
unattended.
2. Inspect the oil for contamination. If the oil is
TROUBLESHOOTING. Trouble shooting a
contaminated with water, it will lose its lubricating and
problem in any of the generator oil systems is fairly cut
cooling capabilities. The primary cause of water
and dry. There are really only four problems that you
contamination is cooler leakage. Also, the oil sumps
will probably encounter. In the following paragraphs,
cannot be purified. Sometimes, in high humidity areas,
we will describe these problems and some of their
condensation forms and cannot be removed. The
probable causes. We will discuss these problems in pairs
condensation thereby contaminates the oil.
because of the similarities in their symptoms and
3. Verify the seawater pressure and flow through
probable causes. Remember, this information is
the cooler. Normally, if flow and pressure are both low,
intended to make your job a little easier; it is not meant
then the seawater strainer is likely clogged. It will be
to replace your use of the approved maintenance
easy to identify if the strainer is clogged. Remember, all
publications.
the generator set coolers are connected in series. You
Low or No Oil Flow. A condition of low or no oil
will probably receive a high turbine oil temperature
flow must be verified locally, unless accompanied by a
alarm before you get a high generator bearing
low-pressure alarm. Always inspect the system for leaks
temperature alarm. If a generator bearing high
first. Afterwards, use the following steps:
temperature alarm is your only indication and a loss of
cooling water is the cause, then either the valves are
1. Verify the oil pressure. If the oil pressure is low,
misaligned or the cooler is clogged.
this condition should be accompanied by an
7-58
