Generators play an important part in your
assignment with the Seabees. Whether operating a
generator as a main power source or as standby power or
as emergency power, you need a through knowledge of
their hookup, operation, and maintenance.
At the completion of this chapter, you should know
how to install generators of the advanced-base type,
stand a generator watch, perform preventive
maintenance, and make minor repairs on power
generators and control equipment.
Theory for both dc and ac generators is included in
Navy Electricity and Electronics Training Series
(NEETS), Module 5. Generator theory will not be
covered in this chapter. Keep in mind that the generator
(alternator) in an automobile works on the same
principle as does the huge turbine generator used in a
nuclear power station.
INSTALLATION AND SERVICING
Most of the generators you are likely to work with
in the Naval Construction Force (NCF) range in size
from 5 kW to 200 kW. Generators in these sizes range
in weight from 488 pounds (221.4 kg) to 10,500 pounds
(4770 kg). All of these units are mounted on skid bases.
Lifting and tie-own attachments are provided. All have
provisions for lifting with a forklift of the appropriate
capacity (with the exception of the 5-kW gas-driven
generator set, which does not include the forklift
Several factors should be considered before a final
decision is made about where to locate a generator. The
noise levels of generators sized from 5 kW to 200 kW
range from 77 dBa to 93 dBa (adjusted decibels) at 25
feet. Generator noise is a problem in low-noise level or
quiet areas (libraries, offices, hospitals, chapels, etc.).
The operating 60-kW generator, for example, presents a
noise hazard (84 dBa to 91 dBa, depending on the
model) to all personnel in the immediate area. The
noise level near the unit exceeds the allowable limits for
unprotected personnel. Therefore, everyone working
around the generator needs single (noise < 84 dBa) or
double hearing protection (noise > 104 dBa).
Placing a generator set near points of large demand
will reduce the size of wire required, hold the line losses
to a minimum, and afford adequate voltage control at
the remote ends of the lines.
The following points should be considered before
an exact site is chosen for a generator set:
1. Generators must not be closer than 25 feet (7.6
meters) to a load because of noise, fire hazard, and air
2. The set must be placed on a stable, preferably
level, foundation. It should not be operated while
inclined more than 15 degrees from level.
3. The site must be within 25 feet (7.6 meters) of
any paralleled generator set and within 25 feet (7.6
meters) of any auxiliary fuel supply.
4. When preparing a temporary installation, you
should move the generator set as close to the jobsite as
practical. In an area where the ground is soft, do not
remove the wood-skid base if you have not already done
so. The wood-skid base will establish a firm foundation
on soft ground, mud, or snow; otherwise, use planks,
logs, or other material for a base in an area where the
ground is soft.
Although advanced-base portable generators are
designed to be operated outdoors, prolonged exposure
to wind, rain, and other adverse conditions will
definitely shorten their lives. When the generators are
to remain on the site for any extended period of time,
they should be mounted on solid-concrete foundations
and should be installed under some type of shelter.
There are no predrawn plans for shelters for a small
advanced-base generating station. The shelter will be
an on-the-spot affairthe construction of which is
determined by the equipment and material on hand plus
your ingenuity, common sense, and ability to cooperate
with personnel in other ratings. Before a Builder can get
started on the shelter, you will have to furnish
information, such as the number of generators to be
sheltered, the dimensions of the generators, the method
of running the generator load cables from the generator
to the panelboard and from the panelboard to the feeder