
SEBU8219-01 109
Maintenance Section
Generator - Inspect
•
Self-circulat
ing air method
•
Oven method
NOTICE
Do not allow the
winding temperature to exceed 85 °C
(185.0 °F). Temperatures that are greater than 85 °C
(185.0 °F) will damage the winding insulation.
Self-Circulating Air Method
Run the engine
and disconnect the generator load.
This will help circulate air. Operate the generator
space heaters.
Oven Method
Place the enti
re generator inside a forced air drying
oven for four hours at 65 °C (149 °F).
NOTICE
Use a forced a
ir type oven rather than a radiant type
oven.
Radiant type
ovens can cause localized overheating.
i01461264
Generator - I
nspect
SMCS Code: 4450-040
Personal injury or death can result from improper
troubleshoo
ting and repair procedures.
The following troubleshooting and repair proce-
dures shoul
d only be performed by qualified per-
sonnel familiar with this e quipm ent.
Refer to Safe
ty Section, “Generator Isolating for
Maintenance” for information regarding the procedure
to safely isolate the generator.
Proper maintenance of electrical equipment requires
periodic visual examination of the generator and
periodic vi
sual examination of the windings. Proper
maintenance of electrical equipment also requires
appropriate electrical checks and appropriate thermal
checks. In
sulation material should be examined for
cracks. The insulation material should be examined
for accumulations of dirt and dust. If there is an
insulatio
n resistance value that is below normal, a
conductive path may be present. This conductive
path may be made of one of the following materials:
•
Carbon
•
Salt
•
Metal dust
•
Dirt that is saturated with moisture
These contami
nants will develop a conductive path
which may produce shorts. Cleaning is advisable if
heavy accumulations of dirt can be seen or if heavy
accumulation
s of dust can be seen. If excess dirt is
the cause of a restriction in the ventilation, cleaning
is also advisable. Restricted ventilation will cause
excessive he
ating.
NOTICE
To avoid the possibility of deterioration to the genera-
tor windings
, do not clean the generator unless there
is visual, electrical, or thermal evidence that dirt is
present.
If harmful dirt accumulations are present, a variety
of cleaning techniques are available. The cleaning
procedure that is used may be determined by one of
the items on the following list:
•
The extent of the cleaning procedure that is being
attempted
•
The type of enclosure of the generator
•
The voltage rating of the generator
•
The type of dirt that is being removed
Cleaning (Assembled Generators)
Cleaning may be required at the point of installation.
At this point, complete disassembly of the generator
may not be necessary or feasible. In this case,
a vacuum cleaner should be used to pick up the
following items: dry dirt, dust, and carbon. This will
prevent the spreading of these contaminants.
A small nonconductive tube may need to be
connected to the vacuum cleaner. This will allow the
vacuum cleaner to clean the surfaces that are not
exposed. After most of the dust has been removed,
a small brush may be attached to the vacuum hose
in order to loosen dirt that is more firmly a ttached to
the surface.
After the initial cleaning with a vacuum, compressed
air may be used to remove the remaining dust and
dirt. Compressed air that is used for cleaning should
be free of moisture and free of oil. Air pressure
should be a maximum of 210 kPa (30 psi) in order to
prevent mechanical damage to the insulation. If the
above cleaning procedures are not effective, consult
a Caterpillar dealer.