4 . An enclosure, which protects all of the
6. Make sure a person qualified in cardiopulmonary
c o m p o n e n t s from dirt, moisture, and mechanical
resuscitation (CPR) is standing by.
damage
On board ship, the most frequent troubles in electrical
When a transformer is used to step up the voltage,
distribution systems will be electrical grounds. Frequent
t h e low-voltage winding is the primary winding.
and proper use of ground detectors provided on the ship's
Conversely, when a transformer is used to step down the
service switchboards and certain power panels will help
v o l t a g e , the high-voltage winding is the primary
you to locate grounds. When troubleshooting, remember
winding. The primary winding is always connected to
the electrical hazards inherent in ungrounded systems
the source of power. The secondary winding is always
resulting from leakage currents.
connected to the load.
To test a switchboard for grounds, use a
megohmmeter (Megger). When preparing to test a
Maintenance
switchboard for grounds, you must first determine if
there is any low-voltage equipment in the circuit you are
The power-handling capacity of a transformer is
testing. The 500-volt output of the Megger could
dependent upon its ability to dissipate heat. If the heat
d a m a g e the components in these circuits. Since
can safely be removed, the power-handling capacity of
transistors, diodes, capacitors, and some rectifiers can
the transformer can be increased. The heat built up in a
be damaged by the high output of the Megger, they must
transformer can be high enough to cause the insulation
be removed or short-circuited before you start testing
around the wire to break down. If this happens, the
for grounds.
transformer may be permanently damaged. To help
prevent this condition, a thorough inspection and
TRANSFORMERS
cleaning of a transformer is necessary.
A transformer transfers energy from one circuit to
INSPECTION.-- Periodically, each transformer
another by electromagnetic induction. This energy is
should be de-energized for a complete inspection and
always transferred without a change in frequency. It is,
c l e a n i n g . Since there are no moving parts in
however, usually transferred with a change in voltage
transformers, inspection is a simple task. This inspection
and current. Transformers are found in many circuits
should not, however, be limited to a visual examination.
a n d components maintained by GSEs. You must
Y o u should check the electrical connections for
u n d e r s t a n d their construction and operation to
looseness by grasping and shaking them.
effectively troubleshoot and repair them.
There is one inspection you can perform while the
transformer is energized. As a competent technician,
Construction
you should be constantly on the look out for
transformers that are operating excessively hot. Take the
The typical transformer has two windings insulated
p r o p e r corrective action quickly to prevent any
electrically from each other. These windings are wound
permanent damage to the transformer.
on a cylindrical or rectangular cardboard form. In effect,
the core material is air and the transformer is called an
C L E A N I N G . -- Dirty windings or clogged
AIR-CORE TRANSFORMER. Transformers used at
ventilation ports will usually cause a transformer to
low frequencies, such as 60 Hz, require a core of
o p e r a t e hotter than normal. When you notice a
low-reluctance magnetic material, usually iron. This
transformer that is operating excessively hot, make
t y p e of transformer is called an IRON-CORE
plans to have it secured and cleaned. YOU can usually
TRANSFORMER. In its most basic form, a transformer
sufficiently clean transformers by wiping them with a
consists of four parts. As shown in figure 5-31, these
dry cloth. Be sure all transformers are completely
four primary parts and their functions areas follows:
de-energized and isolated and remain so until the work
i s completed. Always follow all electrical safety
1. A core, which provides a low-reluctance path for
precautions when you clean transformers.
the magnetic lines of flux
2. A primary winding, which receives energy from
Troubleshooting
the ac source
Transformers are usually trouble-free. Because
3. A secondary winding, which receives energy
transformers normally do not malfunction,
from the primary winding and delivers this energy to the
t r o u b l e s h o o t i n g sh o u l d be a sim p l e t a s k . Si n c e
load
5-36
