controllers. Electric brakes are used to bring a
load to rest, or to hold it at rest, when electric
power to the motor is cut off. Aboard ship,
electric brakes are used primarily on hoisting and
lowering equipment such as cranes, winches, and
Most controllers function simply to start or
to stop auxiliary machinery; but, some controllers
also provide for reversal of direction or multispeed
operation. Motor controllers, sometimes called
starters, have overload protective devices to
prevent burning out the motor. Most controllers
cut out automatically when the electric power
fails, and they have to be restarted manually. This
type of motor controller is called a low-voltage
protection (LVP) controller. Another type of
motor controller, which is used primarily with
vital loads, is called a low-voltage release (LVR)
controller. The LVR controller disconnects the
motor from the supply voltage if the supply
voltage drops below a predetermined level. When
the supply voltage returns to a normal level, the
LVR controller automatically restarts the motor.
Aboard ship, batteries are one of the sources
for emergency and portable power. Storage
batteries are used to power emergency equipment,
ships boats, and forklifts. The storage battery is
also used as a source of energy for emergency
diesel generators, gyrocompasses, and emergency
You should be familiar with safety precautions
you must follow when you work around batteries.
Batteries must be protected from salt water, which
can mix with the electrolyte (the acid solution)
and release poisonous gases. Salt water in the
electrolyte also sets up a chemical reaction that
will ruin the battery. If a battery is exposed to salt
water, notify the electric shop immediately.
Storage batteries, when being charged, give off
a certain amount of hydrogen gas. Battery
compartments should be well ventilated to
discharge this gas to the atmosphere.
Flames or sparks of any kind, including
lighted cigarettes, should never be allowed
in the vicinity of any storage battery that
is being charged.
When the battery is in a low or discharged
state and does not perform properly, you should
notify the Electricians Mate (EM).
Aboard ship, you will perform many jobs
using small, portable electrical tools. Because
portable electrical tools are commonly used under
a variety of conditions, they are subject to damage
The Navy has a good electrical tool safety
program. This program is carried out by qualified
EMs. However, EMs can only make safety checks
on tools that are brought to their attention.
Electrical handtools should be inspected before
each use to make sure the power cord is not nicked
or cut, and the plug is connected properly.
Electrical handtools should be turned in to the
electricians as prescribed by the electrical safety
Relay-operated hand lanterns (fig. 12-11, view
A), usually called battle lanterns, are powered by
dry-cell batteries. Hand lanterns are provided to
give emergency light when the ships service and
emergency/alternate lighting systems fail. These
lanterns are placed in spaces where continual
illumination is necessary, such as machinery
spaces, control rooms, essential watch stations,
battle dressing stations, and escape hatches. All
auxiliary machinery with gauge boards should be
provided with a battle lantern to illuminate the
gauge board in the event of a casualty. The
battle lantern should not be removed from its
mounting bracket except in an emergency. Do not
use it as a flashlight in nonemergency situations.
The relay control boxes for battle lanterns are
connected to the emergency lighting supply
circuit (or to the ships service lighting circuit) in
which the lantern is installed. If power in the
circuit fails, the relay opens and the batteries
energize the lantern.
Relay-operated battle lanterns are capable of
operating for a minimum of 10 hours before the
light output ceases to be useful.
Similar hand lanterns (fig. 12-11, view B),
which are not connected to relays, are installed
throughout the ship to provide light in stations