Suction is preferred to compressed air for
A number of useful tools, and techniques for
removing abrasive dust and particles from
using them, have been developed for doing wire
inaccessible parts. This is because it lessens the
wraps. We have discussed only some of them. For
possibility of damage to insulation. A vacuum
an excellent source on wire-wrapping techniques,
cleaner is good for this purpose. If one is not
refer to MILSTD (military standard) 1130B,
notice 2, 20 July 1983, Connections, Electrical,
available, a flexible tube attached to the suction
side of a portable blower makes a usable vacuum
Solderless, Wrapped.
cleaner. Always exhaust the blower to a suitable
Use caution in working with wire-wrap
sump or overboard. When possible, remove grit,
assemblies. These assemblies look like a bed of
iron dust, and copper particles only by suction
nails, and people have been injured by simply not
taking precautions. A number of injuries occur
methods.
to the face when the technician attempts to get
Clean, dry, compressed air is effective in
removing dry, loose dust and foreign particles,
a good look at the assembly from the side. This
particularly from inaccessible locations such as
exposes the eyes to a needless hazard. Use
air vents in the armature. Use air pressure up to
sufficient lighting to make out details, small
mirrors where possible, and wear safety goggles
30 psi to blow out motors or generators of 50 hp
if a firsthand view from this position is necessary.
or 50 kW or less; use pressure up to 75 psi to blow
When inspecting/repairing the back-planes or
out higher-rated machines. Where air lines carry
higher pressure than is suitable, use a throttling
areas of possible damage, remember that ac or
dc voltages may still be present. Ensure proper
valve to reduce the pressure. Always blow out any
accumulation of water in the air line before
safety precautions are followed for working with
directing the airstream on the part or machine to
energized equipment.
be cleaned.
MOTORS AND GENERATORS
CAUTION
At the shipboard level, maintenance on motors
Be very careful when using compressed
and generators is usually limited to cleaning, bear-
air, particularly if abrasive particles are
ing repair, and brush maintenance. Major repairs,
present because they may be driven into the
such as rewinding and balancing, are done at
insulation and puncture it or be forced
IMAs or shipyards.
beneath insulating tapes. Use compressed
air only after you have opened the equip-
ment on both ends to allow the air and dust
CLEANING MOTORS
to escape. Using compressed air is of little
AND GENERATORS
benefit if the dust is not suitably removed
from the equipment. The most suitable
One of your most important jobs is to keep
method of removing dirt-laden air is to
all electrical machinery clean. Dust, salt, dirt, and
place a suction hose on the opposite end
foreign matter (such as carbon, copper, or mica)
of the equipment where compressed air is
tend to block ventilation ducts. This increases
being used.
resistance to the dissipation of heat and causes
local or general overheating. If the particles form
Whenever possible, avoid the use of solvents
a conducting paste through the absorption of
for cleaning electrical equipment. However, their
moisture or oil, the windings may become short
use is necessary for removing grease and pasty
circuited or grounded. Additionally, abrasive
substances consisting of oil and carbon or dirt.
particles may puncture insulation; iron dust is very
Alcohol will injure most types of insulating
harmful since the dust is agitated by magnetic
varnishes, and it should not be used for cleaning
pulsations. Proper cleaning of motors and
electrical equipment. Because of their high
generators involves the use of wiping rags,
suction, LP air, and solvents.
toxicity, solvents containing gasoline, benzene,
and carbon tetrachloride must NEVER be used
Wiping with a clean, lint-free, dry rag (such
for cleaning purposes.
as cheesecloth) removes loose dust or foreign
Motors, generators, and other electrical equip-
particles from accessible parts. When wiping, do
ment that have been wet with salt water should
not neglect the end windings, slip ring insulation,
be flushed out with fresh water and dried. Never
connecting leads, and terminals.
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