Chapter 2 ABFC Power Plant Operations and Procedures

Chapter 2 ABFC Power Plant Operations and Procedures
Chapter 2
ABFC Power Plant Operations and Procedures
Topics
NAVEDTRA 14027A
1.0.0
Direct Current Generators
2.0.0
Elementary Generator
3.0.0
Elementary DC Generator Components
4.0.0
Classifications of DC Generators (Self
Exciting Type)
5.0.0
Conditions Necessary for Good
Commutation
6.0.0
Inspection of the Commutators and
Collector or Slip Rings
7.0.0
Cleaning Commutators or Collector Rings
8.0.0
AC Generator
9.0.0
Alternator Construction
10.0.0
Single Phase Alternators
11.0.0
Three Phase Alternators
12.0.0
Frequency
13.0.0
Installation
14.0.0
Operation of Power Plant
15.0.0
Single Unit Operation
16.0.0
Parallel Operation
17.0.0
Balancing the Load
18.0.0
Maintaining Frequency
19.0.0
Maintaining Voltage
20.0.0
Demand Factor
21.0.0
Power Factor
22.0.0
Power Factor Correction
23.0.0
Voltage Drop
24.0.0
Hunting
2-1
To hear audio, click on the box.
Overview
Generators play an important part in your assignment with the Seabees. Whether
operating a generator as a main power source or as standby or emergency power, you
need a thorough knowledge of their hookup, operation, and maintenance. At the
completion of this chapter, you should know how to install generators of the advancedbase type, 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 and AC generator
theory was covered in Chapter 1 of this course. Keep in mind that the generator
(or alternator) in an automobile works on the same principle as does the huge turbine
generator used in a nuclear power station.
Objectives
When you have completed this chapter, you will be able to do the following:
1. Describe the different types of Direct Current (DC) generators.
2. Describe the purpose and components of the elementary generator.
3. Identify the classifications of DC generators.
4. Identify the conditions necessary for good commutation.
5. Describe the inspection procedures for commutators and collectors.
6. Describe the cleaning procedures for commutators and collectors.
7. Describe the different types of AC generators.
8. Describe the construction of alternators.
9. Describe the purpose and function of single and three phase alternators.
10. Identify frequency ranges associated with AC generators.
11. Describe the operation of power plants.
12. Describe the procedures for operating single and parallel units.
13. Describe procedures used to balance and maintain frequency and voltage.
14. Identify the demand and power factors.
15. Describe reasons behind voltage drop conditions.
16. Describe hunting.
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Prerequisites
This course map shows all of the chapters in Construction Electrician Advanced. The
suggested training order begins at the bottom and proceeds up. Skill levels increase as
you advance on the course map.
C
Solid State Devices
E
ABFC Power Plant Maintenance
A
D
V
ABFC Power Plant Operations
and Procedures
A
N
C
Advanced Electrical Theory
E
D
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1.0.0 DIRECT CURRENT GENERATORS
A generator is a machine that converts mechanical energy into electrical energy by
using the principle of magnetic induction. This principle is explained as follows.
Whenever a conductor is moved within a magnetic field in such a way that the
conductor cuts across magnetic lines of flux, voltage is generated in the conductor. The
amount of voltage generated depends on the strength of the magnetic field, the angle at
which the conductor cuts the magnetic field, the speed at which the conductor is moved,
and the length of the conductor within the magnetic field.
The polarity of the voltage
depends on the direction of the
magnetic lines of flux and the
direction of movement of the
conductor. To determine the
direction of current in a given
situation, the left-hand rule for
generators is used. This rule is
explained in the following
manner.
Extend the thumb, forefinger, and
middle finger of your left hand at
right angles to one another
(Figure 2-1). Point your thumb in
the direction the conductor is
being moved. Point your
forefinger in the direction of
magnetic flux (from north to
south). Your middle finger will
then point in the direction of
current flow in an external circuit
to which the voltage is applied.
Figure 2-1 — Left-hand rule for generators.
2.0.0 ELEMENTARY GENERATOR
The simplest elementary generator that can be built is an ac generator. Basic
generating principles are most easily explained through the use of the elementary ac
generator. For this reason, we will discuss the ac generator first and the dc generator
later.
An elementary generator consists of a wire loop placed so that it can be rotated in a
stationary magnetic field (Figure 2-2). This will produce an induced electromagnetic field
(emf) in the loop. Sliding contacts (brushes) connect the loop to an external circuit load
in order to pick up or use the induced emf.
The pole pieces (marked N and S) provide the magnetic field. The pole pieces are
shaped and positioned as shown to concentrate the magnetic field as close as possible
to the wire loop. The loop of wire that rotates through the field is called the armature.
The ends of the armature loop are connected to rings called slip rings. They rotate with
the armature. The brushes, usually made of carbon, with wires attached to them, ride
against the rings. The generated voltage appears across these brushes.
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The elementary generator produces a voltage in the following manner (Figure 2-3). The
armature loop is rotated in a
clockwise direction. The initial or
starting point is shown at position
A. This will be considered the
zero-degree position. At 0° the
armature loop is perpendicular to
the magnetic field. The black and
white conductors of the loop are
moving parallel to the field. The
instant the conductors are
moving parallel to the magnetic
field, they do not cut any lines of
flux. Therefore, no emf is induced
in the conductors, and the meter
at position A indicates zero. This
position is called the neutral
plane. As the armature loop
rotates from position A (0°) to
position B (90°), the conductors
cut through more and more lines
of flux at a continually increasing
angle. At 90° they are cutting
Figure 2-2 — The elementary generator.
through a maximum number of
lines of flux and at maximum angle. The result is that between 0° and 90°, the induced
emf in the conductors builds up from zero to a maximum value. Observe that from 0° to
Figure 2-3 — Output voltage of an elementary generator during one revolution.
90°, the black conductor cuts down through the field. At the same time the white
conductor cuts up through the field. The induced emfs in the conductors are seriesadding. This means the resultant voltage across the brushes, the voltage terminal, is the
sum of the two induced voltages. The meter at position B reads maximum value. As the
armature loop continues rotating from 90° (position B) to 180° (position C), the
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conductors which were cutting through a maximum number of lines of flux at position B
now cut through fewer lines. They are again moving parallel to the magnetic field at
position C. They no longer cut through any lines of flux. As the armature rotates from
90° to 180°, the induced voltage will decrease to zero in the same manner that it
increased during the rotation from 0° to 90°. The meter again reads zero. From 0° to
180° the conductors of the armature loop have been moving in the same direction
through the magnetic field. Therefore, the polarity of the induced voltage has remained
the same. This is shown by points A through C on the graph. As the loop rotates beyond
180° (position C), through 270° (position D), and back to the initial or starting point
(position A), the direction of the cutting action of the conductors through the magnetic
field reverses. Now the black conductor cuts up through the field while the white
conductor cuts down through the field. As a result, the polarity of the induced voltage
reverses. Following the sequence shown by graph points C, D, and back to A, the
voltage will be in the direction opposite to that shown from points A, B, and C. The
terminal voltage will be the same as it was from A to C except that the polarity is
reversed as shown by the meter deflection at position D. The voltage output waveform
for the complete revolution of the loop is shown on the graph (Figure 2-3).
3.0.0 ELEMENTARY DC GENERATOR COMPONENTS
A single-loop generator with each terminal connected to a segment of a two-segment
metal ring is shown in Figure 2-4. The two segments of the split metal ring are insulated
from each other. This forms a simple commutator. The commutator in a dc generator
replaces the slip rings of the ac generator. This is the main difference in their
construction. The commutator mechanically reverses the armature loop connections to
the external circuit. This occurs at the same instant that the polarity of the voltage in the
armature loop reverses. Through this process the commutator changes the generated
ac voltage to a pulsating dc voltage as shown in the graph. This action is known as
commutation. Commutation is described in detail later in this chapter.
Figure 2-4 — Effects of commutation.
Refer to Figure 2-4, parts A through D for the remainder of this section. This will help
you in following the step-by-step description of the operation of a dc generator. When
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the armature loop rotates clockwise from position A to position B, a voltage is induced in
the armature loop which causes a current in a direction that deflects the meter to the
right. Current flows through the loop, out of the negative brush, through the meter and
the load, and back through the positive brush to the loop. Voltage reaches its maximum
value at point B on the graph for reasons explained earlier. The generated voltage and
the current fall to zero at position C. At this instant each brush makes contact with both
segments of the commutator. As the armature loop rotates to position D, a voltage is
again induced in the loop. In this case, however, the voltage is of opposite polarity.
The voltages induced in the two sides of the coil at position D are in the reverse
direction to that of the voltages shown at position B. Note that the current is flowing from
the black side to the white side in position B and from the white side to the black side in
position D. However, because the segments of the commutator have rotated with the
loop and are contacted by opposite brushes, the direction of current flow through the
brushes and the meter remains the same as at position B. The voltage developed
across the brushes is pulsating and unidirectional (in one direction only). It varies twice
during each revolution between zero and maximum. This variation is called ripple.
Figure 2-5 – Components of a dc generator.
A pulsating voltage, such as that produced in the preceding description, is unsuitable for
most applications. Therefore, in practical generators more armature loops (coils) and
more commutator segments are used to produce an output voltage waveform with less
ripple.
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Figure 2-5, Views A through E, shows the component parts of dc generators. Figure 2-6
shows the entire generator with the component parts installed. The cutaway figure helps
you to see the physical relationship of the components to each other.
Figure 2-6 – Construction of a dc generator (cutaway drawing).
4.0.0 CLASSIFICATIONS of DC GENERATORS (SELF
EXCITING TYPE)
When a dc voltage is applied to the field windings of a dc generator, current flows
through the windings and sets up a steady magnetic field. This is called field
excitation.
This excitation voltage can be produced by the generator itself or it can be supplied by
an outside source, such as a battery. A generator that supplies its own field excitation is
called a self-excited generator. Self-excitation is possible only if the field pole pieces
have retained a slight amount of permanent magnetism, called residual magnetism.
When the generator starts rotating, the weak residual magnetism causes a small
voltage to be generated in the armature. This small voltage applied to the field coils
causes a small field current. Although small, this field current strengthens the magnetic
field and allows the armature to generate a higher voltage. The higher voltage increases
the field strength, and so on. This process continues until the output voltage reaches the
rated output of the generator. Self-excited generators are classed according to the type
of field connection they use. There are three general types of field connections – serieswound, shunt-wound (parallel), and compound-wound. Compound-wound generators
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are further classified as cumulative-compound and differential-compound. These last
two classifications are not discussed in this chapter.
4.1.0 Series-Wound Generator
In the series-wound generator the field windings are connected in series with the
armature (Figure 2-7). Current that flows in the armature flows through the external
circuit and through the field windings. The
external circuit connected to the generator
is called the load circuit. A series-wound
generator uses very low resistance field
coils, which consist of a few turns of large
diameter wire.
The voltage output increases as the load
circuit starts drawing more current. Under
low-load current conditions, the current that
flows in the load and through the generator
is small. Since small current means that a
small magnetic field is set up by the field
poles, only a small voltage is induced in the
armature. If the resistance of the load
decreases, the load current increases.
Under this condition, more current flows
through the field. This increases the
Figure 2-7 – Series-wound
magnetic field and increases the output
generator.
voltage. A series-wound dc generator has
the characteristic that the output voltage
varies with load current. This is undesirable in most applications. For this reason, this
type of generator is rarely used in everyday practice.
4.2.0 Shunt-Wound Generator
In a shunt-wound generator, like the one shown in Figure 2-8, the field coils consist of
many turns of small wire. They are
connected in parallel with the load. In other
words, they are connected across the
output voltage of the armature.
Current in the field windings of a shuntwound generator is independent of the load
current (currents in parallel branches are
independent of each other). Since field
current, and therefore field strength, is not
affected by load current, the output voltage
remains more nearly constant than does
the output voltage of the series-wound
generator. In actual use, the output voltage
in a dc shunt-wound generator varies
inversely as load current varies. The output
voltage decreases as load current
increases because the voltage drop across
the armature resistance increases (E = IR ) .
In a series-wound generator, output voltage
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Figure 2-8 – Shunt-wound
generator.
2-9
varies directly with load current. In the shunt-wound generator, output voltage varies
inversely with load current. A combination of the two types can overcome the
disadvantages of both. This combination of windings is called a compound-wound dc
generator.
4.3.0 Compound-Wound Generator
Compound-wound generators have a series-field winding in addition to a shunt-field
winding (Figure 2-9). The shunt and series
windings are wound on the same pole
pieces. In the compound-wound generator
when load current increases, the armature
voltage decreases just as in the shuntwound generator. This causes the voltage
applied to the shunt-field winding to
decrease, which results in a decrease in the
magnetic field. This same increase in load
current, since it flows through the series
winding, causes an increase in the
magnetic field produced by that winding.
By proportioning the two fields so that the
decrease in the shunt field is just
compensated by the increase in the series
field, the output voltage remains constant.
This is shown in Figure 2-10, which shows
Figure 2-9 – Compound-wound
the voltage characteristics of the series-,
generator.
shunt-, and compound-wound generators.
As you can see, by proportioning the effects of the two fields (series and shunt), a
compound-wound generator provides a constant output voltage under varying load
conditions. Actual curves are seldom, if ever, as perfect as shown.
Figure 2-10 – Voltage output characteristics.
5.0.0 CONDITIONS NECESSARY for GOOD COMMUTATION
Commutation is the process by which a dc voltage output is taken from an armature that
has an ac voltage induced in it. You should remember from your study earlier in this
chapter about elementary dc generators that the commutator mechanically reverses the
armature loop connections to the external circuit. This occurs at the same instant that
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the voltage polarity in the armature loop reverses. A dc voltage is applied to the load
because the output connections are reversed as each commutator segment passes
under a brush. The segments are insulated from each other.
In Figure 2-11, commutation
occurs simultaneously in the two
coils that are briefly shortcircuited by the brushes. Coil B is
short-circuited by the negative
brush. Coil Y, the opposite coil, is
short-circuited by the positive
brush. The brushes are
positioned on the commutator so
that each coil is short-circuited as
it moves through its own
electrical neutral plane. As you
have seen previously, there is no
voltage generated in the coil at
that time. Therefore, no sparking
can occur between the
commutator and the brush.
Sparking between the brushes
and the commutator is an
indication of improper
commutation. Improper brush
placement is the main cause of
improper commutation.
Figure 2-11 — Commutation of a dc
generator.
6.0.0 INSPECTION of the COMMUTATORS and COLLECTOR
or SLIP RINGS
The first test on an armature
winding should be to locate
grounded circuits. This test is
performed with a series test
lamp. Touch one test prod to the
armature core shaft (Figure 212). Using the other test prod,
touch each commutator segment.
If the armature winding is
grounded, the test lamp will light
when you apply the lamp prod to
the grounded armature winding
or commutator segment. Replace
the grounded armature when all
attempts to remove the ground
have failed.
When checking for a shorted
armature, place the armature in
an armature test set (growler).
Lay the test blade lengthwise
with the flat side loosely in
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Figure 2-12 — Testing for grounds in
armature windings.
2-11
contact with the armature core (Figure 2-13). Turn the test stand to the ON position and
slowly rotate the armature while
you hold the test blade stationary.
If there is a short in the armature
windings, the test blade will be
attracted to the armature
(magnetized) and will vibrate.
CAUTION
Place the test set switch in the
OFF position before removing the
armature, and never leave the
test set turned on unless there is
an armature placed in the core.
When you are testing an
armature for an open circuit,
place the armature in an
armature test set and turn the
test set ON. Place the armature
double prods on two adjoining
commutator segments and note
the reading on the ammeter
(Figure 2-14). Rotate the
Figure 2-13 — Testing for shorts in armature
windings.
armature until each pair of
adjoining commutator segments
has been read. All the segments
should read the same. No
reading indicates an open circuit,
and a high reading indicates a
short circuit.
CAUTION
Place the test set switch in the
OFF position before removing the
armature from the test stand.
Check the commutator for broken
leads. Repair and resolder any
you find. If you find an open
winding, check the commutator
for burned spots. They reveal the
commutator segment to which
the open winding is connected.
Open circuits in the windings
generally occur at the
Figure 2-14 — Testing for opens in a
commutator and can be found by
commutator.
a visual inspection. If there is
excessive sparking at the brushes with the motor reassembled, disassemble it and
replace the armature.
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In testing for a grounded brush holder or rigging, touch one test lamp prod of the
armature test set to the motor housing. With the other test prod, touch each brush
holder individually. If the lamp lights, there is a ground in the brush holder.
CAUTION
Remove all leads to the brush holders and brushes before you attempt this test.
7.0.0 CLEANING COMMUTATORS or COLLECTOR RINGS
The color of the commutator and slip rings will indicate the type of trouble. An even
chocolate-brown color indicates a normal condition, and a black color indicates brush
arcing. You can remove slight burns on the commutator segments by polishing the
commutator as the armature rotates. Use a canvas pad similar to the one shown in
Figure 2-15. To remove deeper burns, use fine sandpaper instead of the canvas pad.
When a commutator is deeply scored, it must be reconditioned in a lathe or with a
special tool.
CAUTION
Never use emery cloth to polish commutators because the emery particles can lodge
between the segments and cause the commutator circuits to short.
Figure 2-15 – Fabricated cleaning pad.
Slip rings used on rotors are usually made of bronze or other nonferrous metals. Under
normal conditions, the wearing surface should be bright and smooth. When the rings
are pitted, they should be polished. When excessively worn and eccentric, they should
be trued with a special tool.
8.0.0 AC GENERATOR
Regardless of size, all electrical generators, whether dc or ac, depend upon the
principle of magnetic induction. An emf is induced in a coil as a result of a coil cutting
through a magnetic field, or a magnetic field cutting through a coil. As long as there is
relative motion between a conductor and a magnetic field, a voltage will be induced in
the conductor. That part of a generator that produces the magnetic field is called the
field. That part in which the voltage is induced is called the armature. For relative motion
to take place between the conductor and the magnetic field, all generators must have
two mechanical parts, a rotor and a stator. The rotor is the part that rotates and the
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stator is the part that remains stationary. In a dc generator, the armature is always the
rotor. In alternators, the armature may be either the rotor or stator.
9.0.0 ALTERNATOR CONSTRUCTION
9.1.0 Rotating-Armature Alternators
The rotating-armature alternator is similar in construction to the dc generator in that the
armature rotates in a stationary magnetic field (Figure 2-16, View A). In the dc
generator, the emf generated in the armature windings is converted from ac to dc by
means of the commutator. In the alternator, the generated ac is brought to the load
unchanged by means of slip rings. The rotating armature is found only in alternators of
low power rating and generally is not used to supply electric power in large quantities.
Figure 2-16 — Types of ac generators.
9.2.0 Rotating-Field Alternators
The rotating-field alternator has a stationary armature winding and a rotating-field
winding (Figure 2-16, View B). The advantage of having a stationary armature winding
is that the generated voltage can be connected directly to the load.
A rotating armature requires slip rings and brushes to conduct the current from the
armature to the load. The armature, brushes, and slip rings are difficult to insulate, and
arc-overs and short circuits can result at high voltages. For this reason, high-voltage
alternators are usually of the rotating-field type. Since the voltage applied to the rotating
field is low voltage dc, the problem of high voltage arc-over at the slip rings does not
exist.
The stationary armature, or stator, of this type of alternator holds the windings that are
cut by the rotating magnetic field. The voltage generated in the armature as a result of
this cutting action is the ac power that will be applied to the load.
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The stators of all rotating-field alternators
are about the same. The stator consists of
a laminated iron core with the armature
windings embedded in this core (Figure 217). The core is secured to the stator frame.
9.3.0 Alternator Components
A typical rotating-field ac generator consists
of an alternator and a smaller dc generator
built into a single unit. The output of the
alternator section supplies alternating
voltage to the load. The only purpose for
the dc exciter generator is to supply the
direct current required to maintain the
alternator field. This dc generator is referred
to as the exciter. A typical alternator is
shown in Figure 2-18, View A, and a
simplified schematic of the generator is
shown in Figure 2-18, View B.
Figure 2-17 – Stationary armature
windings
Figure 2-18 – AC generator pictorial and schematic drawings.
The exciter is a dc, shunt-wound, self-excited generator. The exciter shunt field (2)
creates an area of intense magnetic flux between its poles. When the exciter armature
(3) is rotated in the exciter-field flux, voltage is inducted in the exciter armature
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windings. The output from the exciter commutator (4) is connected through brushes and
slip rings (5) to the alternator field. Since this is direct current already converted by the
exciter commutator, the current always flows in one direction through the alternator field
(6). Thus, a fixed-polarity magnetic field is maintained at all times in the alternator field
windings. When the alternator field is rotated, its magnetic flux is passed through and
across the alternator armature windings (7).
The armature is wound for a three-phase output, which will be covered later in this
chapter. Remember, a voltage is induced in a conductor if it is stationary and a
magnetic field is passed across the conductor, the same as if the field is stationary and
the conductor is moved. The alternating voltage in the ac generator armature windings
is connected through fixed terminals to the ac load.
9.4.0 Alternator Rotors
There are two types of rotors used in rotating-field alternators. They are called the
turbine-driven and salient-pole rotors. As you may have guessed, the turbine-driven
rotor shown in Figure 2-19, View A is used when the prime mover is a high-speed
turbine. The windings in the turbine-driven rotor are arranged to form two or four distinct
poles. The windings are firmly embedded in slots to withstand the tremendous
centrifugal forces encountered at high speeds.
Figure 2-19 – Types of rotors used in alternators.
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The salient-pole rotor shown in Figure 2-19, View B is used in low-speed alternators.
The salient-pole rotor often consists of several separately wound pole pieces bolted to
the frame of the rotor.
If you could compare the physical size of the two types of rotors with the same electrical
characteristics, you would see that the salient-pole rotor would have a greater diameter.
At the same number of revolutions per minute, it has a greater centrifugal force than
does the turbine-driven rotor. To reduce this force to a safe level so that the windings
will not be thrown out of the machine, the salient pole is used only in low-speed designs.
9.5.0 Alternator Characteristics and Limitations
Alternators are rated according to the voltage they are designed to produce and the
maximum current they are capable of providing. The maximum current that can be
supplied by an alternator depends upon the maximum heating loss that can be
sustained in the armature. This heating loss, which is an I 2 R power loss, acts to heat
the conductors, and if excessive, destroys the insulation. Thus, alternators are rated in
terms of this current and in terms of the voltage output – the alternator rating in small
units is in volt-amperes; in large units it is kilovolt-amperes.
When an alternator leaves the factory, it is already destined to do a very specific job.
The speed at which it is designed to rotate, the voltage it will produce, the current limits,
and other operating characteristics are built in. This information is usually stamped on a
nameplate on the case so that the user will know the limitations.
10.0.0 SINGLE-PHASE ALTERNATORS
A generator that produces a single,
continuously alternating voltage is known
as a single-phase alternator. All of the
alternators that have been discussed so far
fit this definition. The stator (armature)
windings are connected in series. The
individual voltages, therefore, add to
produce a single-phase ac voltage. Figure
2-20 shows a basic alternator with its
single-phase output voltage.
The definition of phase as you learned it in
studying ac circuits may not help too much
right here. Remember, “out of phase”
meant “out of time.”
Now, it may be easier to think of the word
“phase” as meaning voltage as in single
voltage. The need for a modified definition
of phase in this usage will be easier to see
as you progress through this chapter.
Figure 2-20 – Single-phase
alternator.
Single-phase alternators are found in many applications. They are most often used
when the loads being driven are relatively light. The reason for this will be more
apparent as you get into multiphase alternators, also called polyphase.
Power that is used in homes, shops, and ships to operate portable tools and small
appliances is single-phase power. Single-phase power alternators always generate
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single-phase power. However, all single-phase power does not come from single-phase
alternators. This will sound more reasonable to you as this chapter continues.
11.0.0 THREE-PHASE ALTERNATOR
The three-phase alternator, as the name implies, has three single-phase windings
spaced such that the voltage induced in any one phase is displaced by 120° from the
other two. A schematic diagram of a three-phase stator showing all the coils becomes
complex, and it is difficult to see what is actually happening. The simplified schematic of
Figure 2-21, View A shows all the windings of each phase lumped together as one
winding. The rotor is omitted for simplicity. The voltage waveforms generated across
each phase are drawn on a graph, phase-displaced 120° from each other. The threephase alternator as shown in this schematic is made up of three single-phase
alternators whose generated voltages are out of phase by 120°. The three phases are
independent of each other.
Figure 2-21 – Three-phase alternator connections.
Rather than having six leads coming out of the three-phase alternator, the same leads
from each phase may be connected together to form a wye (Y) connection (Figure 2-21,
View B). It is called a wye connection because, without the neutral, the windings appear
as the letter Y, in this case sideways or upside down.
The neutral connection is brought out to a terminal when a single-phase load must be
supplied. Single-phase voltage is available from neutral to A, neutral to B, and neutral to
C.
NAVEDTRA 14027A
2-18
In a three-phase, Y-connected alternator, the total voltage, or line voltage, across any
two of the three line leads is the vector sum of the individual phase voltages. Each line
voltage is 1.73 times one of the phase voltages. Because the windings form only one
path for current flow between phases, the line and phase currents are the same or
equal.
A three-phase stator can also be connected so that the phases are connected end-toend; it is now delta connected (Figure 2-21, View C). It is called delta because it looks
like the Greek letter delta (Δ). In the delta connection, line voltages are equal to phase
voltages, but each line current is equal to 1.73 times the phase current. Both the wye
and the delta connections are used in alternators. The majority of all alternators in use
in the Navy today are three-phase machines. They are much more efficient than either
two-phase or single-phase alternators.
11.1.0 Three-Phase Connections
The stator coils of three-phase
alternators may be joined
together in either wye or delta
connections (Figure 2-22). With
these connections only three
wires come out of the alternator.
This allows convenient
connection to three-phase
motors or power distribution
transformers. It is necessary to
use three-phase transformers or
their electrical equivalent with
this type of system.
A three-phase transformer may
be made up of three, singlephase transformers connected
in delta, wye, or a combination
of both. If both the primary and
secondary are connected in
wye, the transformer is called a
wye-wye. If both windings are
connected in delta, the
transformer is called a deltadelta.
Figure 2-22 — Three-phase alternator or
transformer connections.
Figure 2-23 shows single-phase transformers connected delta-delta for operation in a
three-phase system. You will note that the transformer windings are not angled to
illustrate the typical delta (Δ) as has been done with alternator windings. Physically,
each transformer in the diagram stands alone. There is no angular relationship between
the windings of the individual transformers. However, if you follow the connections, you
will see that they form an electrical delta. The primary windings, for example, are
connected to each other to form a closed loop. Each of these junctions is fed with a
phase voltage from a three-phase alternator. The alternator may be connected either
delta or wye depending on load and voltage requirements, and the design of the
system.
NAVEDTRA 14027A
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Figure 2-23 – Three single-phase
transformers connected deltadelta.
Figure 2-24 – Three single-phase
transformers connected wyewye.
Figure 2-24 shows three-phase transformers connected wye-wye. Again, note that the
transformer windings are not angled. Electrically, a Y is formed by the connections. The
lower connections of each winding are shorted together. These form the common point
of the wye. The opposite end of each winding is isolated. These ends form the arms of
the wye.
The ac power on most ships is distributed by a three-phase, three-wire, 450-volt
system. The single-phase transformers step the voltage down to 117 volts. These
transformers are connected delta-delta as in Figure 2-23. With a delta-delta
configuration, the load may be a three-phase device connected to all phases, or it may
be a single-phase device connected to only one phase.
At this point, it is important to remember that such a distribution system includes
everything between the alternator and the load. Because of the many choices that
three-phase systems provide, care must be taken to ensure that any change of
connections does not provide the load with the wrong voltage or the wrong phase.
12.0.0 FREQUENCY
The output frequency of alternator voltage depends upon the speed of rotation of the
rotor and the number of poles. The faster the speed, the higher the frequency. The
lower the speed, the lower the frequency. The more poles there are on the rotor, the
higher the frequency is for a given speed. When a rotor has rotated through an angle
such that two adjacent rotor poles (a north and a south pole) have passed one winding,
the voltage induced in that winding will have varied through one complete cycle. For a
given frequency, the more pairs of poles there are, the lower the speed of rotation. This
principle is illustrated in Figure 2-25; a two-pole generator must rotate at four times the
speed of an eight-pole generator to produce the same frequency of generated voltage.
The frequency of an ac generator in hertz (HZ), which is the number of cycles per
second, is related to the number of poles and the speed of rotation, as expressed by the
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NP
where P is the number of poles, N is the speed of rotation in
120
revolutions per minute (rpm), and 120 is a constant to allow for the conversion of
minutes to seconds and from poles to pairs of poles. For example, a 2-pole, 3600-rpm
alternator has a frequency of 60 HZ, and is determined as follows:
equation F =
Figure 2-25 – Frequency regulation.
2 × 3600
= 60 H Z
120
A 4-pole, 1800-rpm generator also has a frequency of 60 HZ. A 6-pole, 500-rpm
generator has a frequency of:
6 × 500
= 25 H Z
120
A 12-pole, 4000-rpm generator has a frequency of:
12 × 4000
= 400 H Z
120
NAVEDTRA 14027A
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13.0.0 INSTALLATION
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
6 kW generator, for example, presents a noise hazard (84 dBa to 91dBa, 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 circulation.
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.
13.1.0 Site Selection
Before selecting a site, study a plot or chart of the area on which the individual buildings
and facilities have been plotted (Figure 2-26). Select a site large enough to meet
present and anticipated needs. Then select a location with sufficient space on all sides
for servicing and operating the unit. It should be level, dry, and well drained. If this type
NAVEDTRA 14027A
Figure 2-26 – Generator site selection.
2-22
of site is not available, place the generator set on planks or logs for a suitable base
foundation.
13.2.0 Sheltering the Generator
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 solidconcrete foundations and should
be installed under some type of
shelter (Figure 2-27).
There are no predrawn plans for
shelters for a small advancedbase generating station. The
shelter will be an on-the-spot
affair–the construction of which is
determined by the equipment and
material on hand plus your
ingenuity, common sense, and
Figure 2-27 – Generator shelter.
ability to cooperate with
personnel in other ratings. Before a Builder (BU) 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 system outside the
building, and the arrangement of the exhaust system.
Large generator units may have, connected or attached to them, engine equipment that
requires extra space and working area. Included in this equipment are air-intake filters,
silencers for air intake and exhaust, fuel and lubricating oil pumps, tanks, filters, and
strainers. Also included are starting gear, isochronous regulating governors with overspeed trips, safety alarm and shutdown devices, gauges and thermometers, turning
gear, along with platforms, stairs, and railings.
An even larger and more complete power plant may require separate equipment, such
as a motor-driven starting air compressor and air storage tanks; motor-driven pumps for
jacket water and lubricating oil cooling or heat exchangers with raw cooling water
pumps and lubricating oil coolers; and tanks that include day-fuel storage.
Be sure to provide enough working space around each unit for repairs or disassembly
and for easy access to the generator control panels. Installation specifications are
available in the manufacturer’s instruction manual that accompanies each unit. Be sure
to use them. Consulting with the Builder (BU) about these specifications may help cut
installation costs and solve future problems affecting the shelter of the generator.
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13.3.0 Generator Set Inspection
After setting up a portable generator, your crew must do some preliminary work before
placing it in operation. First, they should make an overall visual inspection of the
generator. Have them look for broken or loose electrical connections, bolts, and cap
screws, and see that the ground terminal wire (No. 6 American Wire Gauge (AWG)
minimum) is properly connected to the ground rod/grounding system. Check the
technical manual furnished with the generator for wiring diagrams, voltage outputs,
feeder connections, and prestart preparation. If you find any faults, correct them
immediately.
13.3.1 Generator Connections
When you and your crew install a power plant that has a dual voltage alternator unit,
make certain that the stator coil leads are properly connected to produce the voltage
required by the equipment. Proper grounding is also a necessity for personnel safety
and for prevention of unstable, fluctuating generator output.
13.3.1.1 Internal Leads
The voltage changeover board permits
reconnection of the generator phase
windings to give all specified output voltages
(Figure 2-28). One end of each coil of each
phase winding runs from the generator
through an instrumentation package and a
static exciter current transformer to the
reconnection panel. This routing assures
current sensing in each phase regardless of
voltage connection at the reconnection
board assembly. The changeover board
assembly is equipped with a voltage change
board to facilitate conversion to 120/208 or
240/416 generator output voltage.
Positioning of the voltage change board
connects two coils of each phase in series or
Figure 2-28 – Typical changeover
in parallel. In parallel, the output is 120/208;
board assembly.
in series, the output is 240/416 volts ac. The
terminals on the changeover board
assembly for connection to the generator loads are numbered according to the
particular coil end of each phase of the generator to ensure proper connections.
Remember that you are responsible for the proper operation of the generating unit;
therefore, proceed with caution on any reconnection job. Study the wiring diagrams of
the plant and follow the manufacturer’s instructions to the letter. Before starting the plant
up and closing the circuit breaker, double-check all connections.
NAVEDTRA 14027A
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13.4.0 Grounding
The generator set must be connected to a
suitable ground before operation (Figure 229).
WARNING
Electrical faults in the generator set, load
lines, or load equipment can cause injury or
electrocution from contact with an
ungrounded generator.
13.4.1 Grounding Procedures
The ground can be, in order of preference,
an underground metallic water piping system
(Figure 2-30, View A), a driven metal rod
(Figure 2-30, View B), or a buried metal plate
(Figure 2-30, View C). A ground rod must
have a minimum diameter of 5/8 inches if
solid or ¾ inches if pipe. The rod must be
driven to a minimum depth of 8 feet. A
ground plate must have a minimum area of 2
square feet and, where practical, be
embedded below the permanent moisture
level.
Figure 2-29 – Generator start up
warning label.
The ground lead must be at least No. 6 AWG
copper wire. Be sure to bolt or clamp the
lead to the rod, plate, or piping system.
Connect the other end of the ground lead to
the generator set ground terminal stud
(Figure 2-31, View A).
Use the following procedure to install ground
rods:
•
Install the ground cable into the slot in
the ground stud and tighten the nut
against the cable.
Figure 2-30 – Methods of
grounding generators.
•
Connect a ground rod coupling to the
rod and install the driving stud in the
coupling (Figure 2-31, View B). Make sure that the driving stud is bottomed on
the ground rod.
•
Drive the ground rod into the ground until the coupling is just above the ground
surface.
•
Connect additional rod sections, as required, by removing the driving stud from
the coupling. Make sure the new ground rod section is bottomed on the ground
rod section previously installed. Connect another coupling on the new section
and again install the driving stud.
NAVEDTRA 14027A
2-25
•
After the rod(s) have been driven into the ground, remove the driving stud and
the top coupling.
Figure 2-31 – Grounding procedure.
NOTE
The National Electrical Code© states that a single electrode consisting of a rod, pipe, or
plate that does not have a resistance to ground of 25 ohms or less will be augmented by
additional electrodes. Where multiple rod, pipe, or plate electrodes are installed to meet
the requirements, they will be not less than 6 feet apart.
The resistance of a ground electrode is determined primarily by the earth surrounding
the electrode. The diameter of the rod has only a negligible effect on the resistance of a
ground. The resistance of the soil is dependent upon the moisture content. Electrodes
should be long enough to penetrate a relatively permanent moisture level and should
extend well below the frost line. Make periodic earth resistance measurements,
preferably at times when the soil can be expected to have the least moisture.
You need to test the ground rod installation to be sure it meets the requirement for
minimum earth resistance. Use the earth resistance tester to perform the test. You
should make this test before you connect the ground cable to the ground rod.
When ground resistances are too high, they may be reduced by one of the following
methods:
NAVEDTRA 14027A
2-26
•
Using additional ground rods is one of the best means of reducing the resistance
to ground. For example, the combined resistance of two rods properly spaced
and connected in parallel should be 60 percent of the resistance of one rod; the
combined resistance of three rods should be 40 percent of that of a single rod.
•
Longer rods are particularly effective where low-resistance soils are too far below
the surface to be reached with the ordinary length rods. The amount of
improvement from the additional length on the rods depends on the depth of the
low-resistance soils. Usually, a rather sharp decrease in the resistance
measurements is noticeable when the rod has been driven to a low-resistance
level.
•
Treating the soil around ground rods is a reliable and effective method for
reducing ground resistance and is particularly suitable for improving high
resistance ground. The treatment method is advantageous where long rods are
impractical because of rock strata or other obstructions to deep driving. There
are practical ways of accomplishing this result (Figure 2-32). Where space is
limited, a length of tile pipe is sunk in the ground a few inches from the ground
rod and tilled to within 1 foot or so of the ground level with the treatment chemical
(Figure 2-32, View A). Examples of suitable non-corrosive materials are
magnesium sulfate, copper sulfate, and ordinary rock salt. The least corrosive is
magnesium sulfate, but rock salt is cheaper and does the job.
•
The second method is applicable where a circular or semicircular trench can be
dug around the ground rod to hold the chemical (Figure 2-32, View B). The
chemical must be kept several inches away from direct contact with the ground
rod to avoid corrosion of the rod. If you wish to start the chemical action promptly,
flood the treatment material. The first treatment usually contains 50 to 100
pounds of material. The chemical will retain its effectiveness for 2 to 3 years.
Each replenishment of the chemical extends the effectiveness for a longer period
so that the necessity for future retreating becomes less and less frequent.
•
A combination of methods may be advantageous and necessary to provide
desired ground resistance. A combination of multiple rods and soil treatment is
effective and has the advantages of both of these methods; multiple long rods
are effective where conditions permit this type of installation.
After you are sure you have a good ground, connect the clamp and the ground cable to
the top ground rod section, and secure the connection by tightening the screw (Figure
2-32, View B).
NAVEDTRA 14027A
2-27
Figure 2-32 – Methods of soil treatment for lowering of ground resistance.
13.4.2 Grounding Connections
A typical generator set is outlined in Figure 2-33, showing the load cables and output
load terminals.
WARNING
Before attempting to connect the load cables to the load terminals of a generator set,
make sure the set is not operating and there is no input to the load.
Refer to Figure 2-33 as you follow this procedural discussion for making load
connections.
1. Open the access door and disconnect the transparent cover by loosening six
quick-release fasteners. Remove the wrench clipped to the cover. Be sure to
maintain the proper phase relationship between the cable and the load terminals,
that is, A0 to L1, B0 to L2, and so forth.
2. Attach the load cables in the following order: L0, L3, L2, and L1 as specified in
Step 3 below.
3. Insert the load cables through the protective sleeve. Attach the cables to their
respective load terminals, one cable to each terminal, by inserting the cable in
the terminal slot and tightening the terminal nut with the wrench that was clipped
to the transparent cover. Install the wrench on the cover and install the cover.
NAVEDTRA 14027A
2-28
4. Tighten the drawstring on the protective sleeve to prevent the entry of foreign
matter through the hole around the cable.
You may convert the voltage at the load terminals to 120/208 volts or 240/416 volts by
properly positioning the voltage change board (Figure 2-28). The board is located
directly above the load terminal board.
Figure 2-33 – Load cable connections.
The procedure for positioning the voltage change board for the required output voltage
is as follows:
1. Disconnect the transparent cover by loosening the six quick-release
fasteners.
2. Remove the 12 nuts from the board. Move the change board up or down to
align the change board arrow with the required voltage arrow. Tighten the 12
nuts to secure the board.
3. Position and secure the transparent cover with the six quick-release fasteners
and close the access door.
NAVEDTRA 14027A
2-29
13.4.3 Generator Connections
When you install a power plant that has a dual voltage alternator unit, make certain that
the stator coil leads are properly connected to produce the voltage required by the
equipment.
Proper grounding is also a necessity for personnel safety and for prevention of unstable,
fluctuating generator output.
13.4.3.1 Internal Leads
The voltage changeover board permits reconnection of the generator phase windings to
give all specified output voltages. One end of each coil of each phase winding runs from
the generator through an instrumentation and a static exciter current transformer to the
reconnection panel. This routing assures current sensing in each phase regardless of
voltage connection at the reconnection board assembly. The changeover board
assembly is equipped with a voltage change board to facilitate conversion to 120/208 or
240/416 generator output voltage. Positioning of the voltage change board connects two
coils of each phase in series or in parallel. In parallel, the output is 240/416; in series,
the output is 120/208 volts ac. The terminals on the changeover board assembly for
connection to the generator loads are numbered according to the particular coil end of
each phase of the generator to ensure proper connections.
Remember, you are responsible for the proper operation of the generating unit;
therefore, proceed with caution on any reconnection job. Study the wiring diagrams of
the plant and follow the manufacturer’s instructions to the letter. Before you start the
plant up and close the circuit breaker, double-check all connections.
13.4.3.2 Grounding
It is imperative to solidly ground all electrical generators operating at 600 volts or less.
The ground can be, in order of preference, an underground metallic water piping
system, a driven metal rod, or a buried metal plate. A ground rod has to have a
minimum diameter of 5/8 inch if solid and 3/4 inch if pipe, and it has to be driven to a
minimum of 8 feet. A ground plate has to be a minimum of 2 square feet and be buried
at a minimum depth of 2 l/2 feet. For the ground lead, use No. 6 AWG copper wire and
bolt or clamp it to the rod, plate, or piping system. Connect the other end of the ground
lead to the generator set ground stud.
The National Electrical Code® states that a single electrode consisting of a rod, pipe, or
plate that does not have a resistance to ground of 25 ohms or less will be augmented by
additional electrodes. Where multiple rod, pipe, or plate electrodes are installed to meet
the requirements, they are required to be not less than 6 feet apart.
It is recommended that you perform an earth resistance test before you connect the
generator to ground. This test will determine the number of ground rods required to
meet the requirements, or the necessity of constructing a ground grid.
13.4.3.3 Feeder Cable Connections
While the electric generator is being installed and serviced, a part of your crew can
connect it to the load. Essentially, this connection consists of running wire or cable from
the generator to the load. At the load end, the cable is connected to a distribution
terminal. At the generator end, the cable is connected either to the output terminals of a
main circuit breaker or a load terminal board. Before running the wires and making the
connections, do the following:
NAVEDTRA 14027A
2-30
•
Determine the correct size of wire or cable to use.
•
Decide whether the wire or cable will be buried, carried overhead on poles, or run
in conduit.
•
Check the generator lead connections of the plant to see that they are arranged
for the proper voltage output.
13.4.3.3.1 Cable Selection
If you use the wrong size conductor in the load cable, various troubles may occur. If the
conductor is too small to carry the current demanded by the load, it will heat up and
possibly cause a fire or an open circuit. Even though the conductor is large enough to
carry the load current safely, its length might result in a lumped resistance that produces
an excessive voltage drop. An excessive voltage drop results in a reduced voltage at
the load end. This voltage drop should not exceed 3 percent for power loads, 3 percent
for lighting loads, or 5 percent for combined power and lighting loads.
Select a feeder conductor capable of carrying 150 percent of rated generator amperes
to eliminate overloading and voltage drop problems. Refer to the National Electrical
Code® tables for conductor ampacities. The tables are 310-16, 310-17, 310-18, and
310-19. Also refer to the notes to ampacity tables following Table 310-19 in the NEC®.
13.4.3.3.2 Cable Installation
The load cable may be installed overhead or underground. In an emergency installation,
time is the important factor. It may be necessary to use trees, pilings, 4 by 4s, or other
temporary line supports to complete the installation. Such measures are temporary;
eventually, you will have to erect poles and string the wire or bury it underground. If the
installation is near an airfield, it may be necessary to place the wires underground at the
beginning. Wire placed underground should be direct burial, rubber-jacketed cable;
otherwise, it will not last long.
Direct burying of cable for permanent installation calls for a few simple precautions to
ensure uninterrupted service. They are as follows:
•
Dig the trench deep enough to bury the cable at least 18 inches (24 inches in
traffic areas and under roadways) below the surface of the ground to prevent
disturbance of the cable by frost or subsequent surface digging.
•
After laying the cable and before backfilling, cover it with soil free from stones,
rocks, and so forth. That will prevent the cable from being damaged in the event
the surrounding soil is disturbed by flooding or frost heaving.
14.0.0 OPERATION of POWER PLANT
When you are in charge of a generating station, you will be responsible for scheduling
around-the-clock watches to ensure a continuous and adequate supply of electrical
power. Depending on the number of operating personnel available, the watches are
evenly divided over the 24-hour period. A common practice is to schedule 6-hour
watches, or they may be stretched to 8-hour watches without working undue hardship
on the part of the crew members. Avoid watches exceeding 8 hours, however, unless
emergency conditions dictate their use.
The duties assigned to the personnel on generator watches can be grouped into three
main categories: (1) operating the equipment, (2) maintaining the equipment, and (3)
keeping the daily operating log. Operating and maintaining the generating equipment
NAVEDTRA 14027A
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will be covered in the succeeding sections of this chapter, so for the present you can
concentrate on the importance of the third duty of the station operator—keeping a daily
operating log.
The number of operating hours is recorded in the generating station log. The log serves
as a basis for determining when a particular piece of electrical equipment is ready for
inspection and maintenance. The station log can be used in conjunction with previous
logs to spot gradual changes in equipment condition that ordinarily are difficult to detect
in day-to-day operation. It is particularly important that you impress upon your watch
standers the necessity for taking accurate readings at periods specified by local
operating conditions.
Ensure that watch standers keep their spaces clean and orderly. Impress on them the
importance of keeping tools and auxiliary equipment in their proper places when not in
use. Store clean waste and oily waste in separate containers. Oily waste containers are
required to be kept covered. Care given to the station floor will be governed by its
composition. Generally, it should be swept down each watch. Any oil or grease that is
tracked around the floor should be removed at once.
14.1.0 Generator Watch
Personnel you assign to stand the generator watch must be alert and respond quickly
when they recognize a problem. The watch standers might not have control of every
situation, but at least they need to be capable of securing the generator and preventing
serious problems.
The primary purpose of the generator watch is to produce power in a safe and
responsible manner. The watch stander may notice maintenance or repair actions that
need to be rectified but do not require their immediate attention. The generator watch
needs to make note of these problems so that they will be taken care of by the repair
crew.
A generator watch involves performing operator maintenance, maintaining the
operator’s log, operating a single generator, or operating paralleled generators.
14.2.0 Operator’s Log
The operator’s log (also called the station log) is a complete daily record of the
operating hours and conditions of the generator set. The log must be kept clean and
neat. The person who signs the log for a watch must make any corrections or changes
to entries for that watch.
The log serves as a basis for determining when a particular piece of electrical
equipment is ready for inspection and maintenance. Current and previous logs can be
compared to spot gradual changes in equipment condition. These changes might not
otherwise be detected in day-to-day operation.
Note defects discovered during operation of the unit for future correction; such
correction should be made as soon as operation of the generator set has ceased.
Making accurate periodic recordings is particularly important. The intervals of these
recordings will be based on local operating conditions.
The form used for log entries varies with the views of the supervisory personnel in
different plants, and there is no standard form to be followed by all stations. Regardless
of form, any log must describe the hourly performance not only of the generators but
also of the numerous indicating and controlling devices.
NAVEDTRA 14027A
2-32
Figure 2-34 shows one type of log that may be kept on the generator units of a power
plant. This is only a suggested form, of course, and there may be many other forms at
your generating station to keep records on.
Figure 2-34 – Typical generating station operator’s log.
14.3.0 Plant Equipment
Setting up a power generator is only one phase of your job. After the plant is set up and
ready to go, you will be expected to supervise the activities of the operating personnel
of the generating station. In this respect, you should direct your supervision toward one
ultimate goal--to maintain a continuous and adequate flow of electrical power to meet
the demand. That can be accomplished if you have a thorough knowledge of how to
operate and maintain the equipment and a complete understanding of the station’s
electrical systems as a whole. Obviously, a thorough knowledge of how to operate and
maintain the specific equipment found in the generating station to which you are
assigned cannot be covered here; however general information will be given. It will be
up to you to supplement this information with the specific instructions given in the
manufacturer’s instruction manuals furnished with each piece of equipment.
Similarly, you can gain familiarity with the station’s electrical system as a whole only by
studying information relating specifically to that installation. This information can be
found to some extent in the manufacturer’s instruction manuals. You can obtain the
greater part of it from the station’s electrical plans and wiring diagrams. Remember,
however, to supplement your study of the electrical plans and diagrams with an actual
study of the generating station’s system. That way, the generators, switchgear, cables,
and other electrical equipment are not merely symbols on a plan but are physical
NAVEDTRA 14027A
2-33
objects whose locations you definitely know and whose functions and relation to the rest
of the system you thoroughly understand.
15.0.0 SINGLE UNIT OPERATION
Connecting an electric plant to a de-energized bus involves two general phases: (1)
starting the diesel engine and bringing it up to rated speed under control of the governor
and (2) operating the switchboard controls to bring the power of the generator onto the
bus.
Different manufacturers of generating plants require the operator to perform a multitude
of steps before starting the prime mover; for example, if a diesel engine is started by
compressed air, the operator would have to align the compressed air system. This
alignment would not be necessary if the engine is of the electric-start type. It is
important that you, as the plant supervisor, establish a prestart checklist for each
generating plant. The prestart checklist provides a methodical procedure for confirming
the operational configuration of the generating plant; following this procedure assures
that all systems and controls are properly aligned for operation. This section will first
give general information and have a separate section for the Tactical Quiet Generator
(TQG-B).
The checklist mentioned above should include, but is not limited to, the following:
1. Align ventilation louvers.
2. Check lube oil, fuel oil, and cooling water levels.
3. Ensure battery bank is fully charged.
4. Align electrical breakers and switches for proper operation of auxiliary
equipment.
5. Check control panel and engine controls.
6. Select the proper operating position for the following controls for single plant
operation.
•
Voltage regulator switch to UNIT or SINGLE position.
•
Governor switch to ISOCHRONOUS or SINGLE position.
NOTE: Adjust hydraulic governor droop position to 0.
•
Voltage regulator control switch to AUTO position.
Complete the prestart checklist in sequence before you attempt to start the generating
plant.
Start the generating plant and adjust the engine revolutions per minute (rpm) to
synchronous speed. Adjust the voltage regulator to obtain the correct operating voltage.
Set the synchronizing switch to the ON position and close the main circuit breaker.
Adjust the frequency to 60 hertz with the governor control switch. Perform hourly
operational checks to detect abnormal conditions and to ensure the generating set is
operating at the correct voltage and frequency.
15.1.0 Operating Procedures for Single Generator Sets (General)
The following operating procedures are general procedures for operating a single
generator unit. Some procedures will vary with different types of generators. Study
carefully the recommendations in the manufacturer’s manual for the generator you are
NAVEDTRA 14027A
2-34
to operate. Learn about the capabilities and limitations of your machine(s). In the event
of a problem, you will know what action is required to lessen the effects of the problem.
You or your senior should make a checklist of operating procedures from the manual
and post it near the generator.
The steps below will cover starting and operating a typical diesel-driven generator set.
(This set uses a dc powered motor for starting the diesel engine.) These steps will also
cover applying an electrical load.
15.1.1 Starting the Generator Set (General)
Proceed as follows to start the typical generator set:
WARNING
Do not operate the generator set unless it
has been properly grounded. Electrical
faults (such as leakage paths) in the
generator set, feeder lines, or load
equipment can cause injury or death by
electrocution.
Before operating the set for the first time,
ensure that service procedures were
performed upon its receipt according to the
manufacturer’s literature. See also that all
preventive maintenance checks have been
performed. The voltage change board must
be adjusted for the required voltage (Figure
2-35).
1. Open the CONTROL CUBICLE and
AIR INTAKE DOORS (Figure 2-36).
Close the HOUSING PANEL
(ACCESS) DOORS.
Figure 2-35 – Typical changeover
board assembly.
2. Set the FUEL TRANSFER VALVE (Figure 2-36) to the desired source of fuel,
preferably the auxiliary tank, if it is connected.
NAVEDTRA 14027A
2-35
Figure 2-36 – Generator set, left rear, three quarters view.
NOTE
Refer to Figure 2-37 for the for the CONTROL CUBICLE, FAULT INDICATOR PANEL,
DC CONTROL CIRCUIT BREAKER, and ENGINE MANUAL SPEED CONTROL.
Notice that the control cubicle is divided into an engine section and a generator section.
3. Set the PARALLEL OPERATION - SINGLE UNIT OPERATION select switch
(located in the GENERATOR section of the CONTROL CUBICLE) to SINGLE
UNIT OPERATION.
4. Set the VOLTAGE ADJUST - INCREASE control to the lower half of the
adjustment range.
5. Depress the DC CONTROL CIRCUIT BREAKER (located to the lower right of the
CONTROL CUBICLE) to ON.
6. Set the START - STOP - RUN switch (located in the ENGINE section of the
CONTROL CUBICLE) to RUN.
7. Set and hold the TEST or RESET switch (on the FAULT INDICATOR PANEL) in
the UP position. Check each fault indicator light that is on and replace defective
lamps or fuses.
8. Allow the TEST or RESET switch to return to the mid position. Each fault
indicator light, with the exception of the LOW OIL Pressure light, should go out.
When the engine has started, the LOW OIL PRESSURE light should also go out.
NAVEDTRA 14027A
2-36
If the NO FUEL light stays lit, refill the set or auxiliary tank. Position the BATTLE
SHORT switch (CONTROL CUBICLE) to ON (the fuel pump will run to fill the day tank).
Figure 2-37 – Control cubicle, controls, and indicators.
Set the TEST or RESET switch to the UP position and then release it; the NO FUEL
light should go out when the switch handle is released.
9. Set the CKT BRK CLOSE - OPEN switch (CONTROL CUBICLE) to OPEN.
10. Push and release the AIR CLEANER CONDITION indicator, BATTLE SHORT
indicator, and CKT BKR indicator. EACH indicator light should go on as the
indicator is pushed and go out when the indicator is released.
a. If the AIR CLEANER CONDITION indicator remains lit, the air cleaner
must be serviced.
b. If the CKT BKR indicator remains on after you set the CKT BRK switch to
OPEN, you cannot continue the procedure. The circuit breaker must
function properly. The generator cannot be used until the problem is
corrected.
11. Depress the lock button on the ENGINE MANUAL SPEED CONTROL (located
below the DC CONTROL CIRCUIT BREAKER), and set the control.
CAUTION
Do NOT crank the engine in excess of 15 seconds at a time. Allow the starter to cool a
minimum of 3 minutes between cranking.
NAVEDTRA 14027A
2-37
WARNING
Operation of this equipment presents a noise hazard to personnel in the area. The noise
level exceeds the allowable limits for unprotected personnel. Wear earmuffs or
earplugs.
12. Set and hold the START - STOP - RUN switch to the START position until the
engine starts. As the engine starts, observe the following:
a. The OIL PRESSURE gauge indicates at least 25 pounds per square inch
gauge (psig).
b. The VOLTS AC meter indicates the presence of voltage.
c. The LOW OIL PRESSURE indicator light on the FAULT INDICATOR
PANEL goes out.
13. Release the START - STOP - RUN switch. Position the switch to RUN.
15.1.2 Operating the Generator Set (General)
The procedures for operating a single generator set (single unit) are as follows:
1. Ensure that the PARALLEL OPERATION - SINGLE UNIT OPERATION switch is
set to SINGLE UNIT OPERATION.
2. Position the AMPS – VOLTS selector switch to the required position. Rotate the
VOLTAGE ADJUST control to obtain the required voltage. Read the voltage from
the VOLTS AC meter.
3. Depress the locking button and slide the ENGINE MANUAL SPEED CONTROL
in or out to obtain the approximate rated frequency; rotate the vernier knob (the
knob on the control) clockwise or counterclockwise to obtain the rated frequency.
NOTE
If necessary, the load may be applied immediately.
4. Operate the engine for at least 5 minutes to warm it up.
5. Apply the load by holding the CKT BRK switch (on the CONTROL CUBICLE) to
CLOSE until the CKT BRK indicator lights go out. Then release the switch.
6. Observe the readings from the VOLTS AC meter and the HERTZ
(FREQUENCY) meter. The voltage readings should be 120/208 to 240/416 volts
ac (depending on the positions of the AMPS-VOLTS select switch and the
voltage change board). Let us say, for example, that you positioned the voltage
change board for 120/208 volts before you started the generator set. When you
position the AMPS-VOLTS selector switch to L2-L0 VOLTS/L2 AMPS while the
generator is operating, the VOLTS AC meter should indicate 120 volts. The
PERCENT RATED CURRENT meter will indicate the percent rated current (not
more than 100 percent) between generator line 2 and neutral. The HERTZ
(FREQUENCY) meter should indicate 50 or 60 hertz. The KILOWATTS meter
should indicate no more than 100 percent with the HERTZ (FREQUENCY) meter
showing 60 hertz. Readjust the voltage and frequency, if necessary.
7. Observe the KILOWATTS meter. If the meter indicates that more than the rated
kilowatts are being consumed, reduce the load.
NAVEDTRA 14027A
2-38
8. Rotate the AMPS-VOLTS selector switch to each phase position and monitor the
PERCENT RATED CURRENT meter. If it indicates more than the rated load for
any phase position, reduce or reapportion the load.
9. Periodically (not less than once per hour), monitor the engine and generator
indicators to ensure their continued operation.
10. Perform any preventive checks.
When in operation, monitor the generator set periodically (at least once an hour) for
signs indicating possible future malfunctions.
After the warm-up, the lubricating oil pressure should remain virtually constant. Check
and record the level of lubricating oil while the engine is running normally. If any
significant changes occur in the oil pressure, notify maintenance personnel. Check and
record the coolant temperature of the normally running engine. Notify maintenance
personnel if the coolant temperature changes significantly.
Learn the sounds of a normally running generator set so that you may detect any
unusual sounds indicating the possible start of a malfunction may be detected early
enough to avoid major damage.
Stop the operation immediately if a deficiency that would damage the equipment is
noted during operation.
15.2.0 Operating Procedures for Single Generator TQG-B
This section is about the single
operating procedures for the
TQG-B generator. Before the
operating procedures are
discussed, it is important that
you understand the components
that make up the TQG-B (Figure
2-38). Failure to understand
these components could lead to
personnel injury or death and
damage to the generator.
Before learning about the
components and operating
procedures of the TQG-B, take
a moment to read the next two
important safety warnings
(Figure 2-39). It is imperative for
you to take each warning
seriously. (1) Remember to
make sure the unit is completely
shut down and free of any
Figure 2-38 – TQG-B Generator.
power source before attempting
any repair or maintenance on the unit. High voltage is produced when the generator set
is in operation and failure to comply with this safety procedure can result in injury or
death to personnel. (2) Remember to remove metal jewelry when working on electrical
systems or components. Metal jewelery can conduct electricity, and failure to comply
with this safety procedure can cause injury or death to personnel by electrocution.
NAVEDTRA 14027A
2-39
The TQG-Bravo recently took the place of
the Alpha model. There are similarities
between the Alpha and Bravo models. Both
models deliver the same precise power with
the same voltage and frequency. Both
generators also have the same engines:
John Deere Diesel/JP-8 engines. The
following is a listing of similarities between
both models:
•
Both models deliver the same
precise power, voltage, and
frequency levels.
•
Both have the same engines.
•
Output: 30,000 Kw.
•
Voltage: 120/208 low wye.
240/416 high wye.
•
Frequency: 50 – 60 HZ.
•
Engine: John Deere JP-8 Diesel
Figure 2-39 – Warning notices.
While the Alpha and Bravo models do have some similarities, they also have some
important differences that you need to be aware of. The bravo model has a Digital
Control System or DCS, while the Alpha model uses physical gauges, lights, and
meters. It is important to know that you cannot parallel a TQG-Alpha with a TQG-Bravo.
Attempting to do so will result in damage to the generator sets.
15.2.1 Components and Instrumentation of the TQG-B
The TQG-Bravo models have several
components and instruments with which
you need to be familiar. You will learn about
the components and instruments in a 360°
rotation starting at the rear and completing
on the right side of the generator.
Refer to Figure 2-40 for the rear portion of
TQG-B.
15.2.1.1 Rear: Components and
Instruments
15.2.1.1.1 DCS
Figure 2-40 is the DCS that you will use to
start, operate, and shut down the TQG-B. It
is extremely important that you know the
function of each component and instrument
on the DCS.
NAVEDTRA 14027A
Figure 2-40 – TQG-B rear
components.
2-40
15.2.1.1.2 Air Cleaner Assembly
The air cleaner assembly is located on the front, behind the air cleaner access door.
The air cleaner assembly has a dry-type, disposable paper filter and canister. There is
also a restriction indicator which will pop up during operation when the air cleaner
requires servicing.
15.2.1.1.3 Paralleling Receptacle
The paralleling receptacle is used to connect the paralleling cable between two
generator sets of the same size and model to operate in parallel.
15.2.1.1.4 Convenience Receptacle
The convenience receptacle is a 120 VAC receptacle used to operate small plug-in type
equipment. This can be used to operate a laptop or other normal appliances.
15.2.1.1.5 Ground Fault Circuit Interrupter Test Switch
The ground fault circuit interrupter consists of the test switch and reset switches. The
test switch tests to see if the ground fault circuit interrupter is working. The reset switch
resets the ground fault circuit interrupter.
15.2.1.2 Left Side Components and Instrumentation
Refer to Figure 2-41 for the left side portion of TQG-B.
15.2.1.2.1 Radiator
The radiator is in the front of the engine
compartment. It acts as a heat exchanger
for the engine coolant and helps keep the
engine cool.
15.2.1.2.2 Dead Crank Switch
The dead crank switch is located on the left
side of the engine compartment. The switch
allows for engine turn-over without starting
for maintenance purposes.
15.2.1.2.3 Dipstick
The dipstick is on the left side of the engine
compartment. The dipstick measures the oil
level in the engine drain pan. It has two
sides, an engine stopped or cold side and
an engine running or hot side.
Figure 2-41 – Left side
components of the TQG-B
generator.
15.2.1.2.4 Fuel Drain Valve
The fuel drain valve is on the left side of the generator set’s skid base. The fuel drain
allows fuel to be drained for maintenance.
15.2.1.2.5 AC Generator
The ac generator is coupled directly to the rear of the diesel engine and is the
component that produces electricity using the energy from the diesel engine.
NAVEDTRA 14027A
2-41
15.2.1.2.6 Actuator
The actuator is on the engine’s left side. The actuator regulates fuel amounts that enter
the engine to maintain the desired engine speed.
15.2.1.2.7 Turbocharger
The engine’s turbocharger takes air from the intake filter. Exhaust gases are pushed
into the turbine of the turbocharger through the exhaust manifold. The turbine drives the
turbocharger, which compresses the intake air and forces it into the engine, creating
more powerful explosions in the combustion chambers.
15.2.1.2.8 Fuel Pump
The fuel pump is on the engine’s left side. It delivers fuel to the Fuel Injection Pump.
15.2.1.2.9 Magnetic Pickup
The magnetic pickup is on the rear bell housing of the engine’s flywheel. It uses
magnetic impulses to monitor engine speed for the governor control unit.
15.2.1.3 Front End Components and Instrumentation
Refer to Figure 2-42 for the front end portion of TQG-B.
15.2.1.3.1 Batteries
Two maintenance-free 12-volt dc batteries
are located at the front of the TQG-B. The
generator is capable of operating without
the batteries connected after it is started.
There is a diode behind the control panel
that protects the generator set if the
batteries are connected incorrectly.
15.2.1.3.2 Oil Drain-Off Valve
The oil drain valve is located at the front of
the generator. This is where oil is drained
for maintenance purposes.
15.2.1.4 Right Side Components and
Instrumentation
Refer to Figure 2-43 for the right side
portion of TQG-B.
Figure 2-42 – Front end
components of the TQG-B
generator.
15.2.1.4.1 NATO Slave Receptacle
The NATO slave receptacle is located on the right side of the generator set. The NATO
receptacle is used for remote battery operation and jump starting the unit from any other
piece of equipment that has a 24 VDC starting system.
15.2.1.4.2 Load Output Terminal
The load output terminal board is at the rear of the generator on the right side. It
consists of four ac output terminals mounted on a board. The four terminals are labeled
L1, L2, L3, and L0. There is also a fifth terminal labeled GND that serves as the ground
NAVEDTRA 14027A
2-42
for equipment. A copper bar is connected between the L0 and GND terminals (Figure 243).
15.2.1.4.3 Reconnection Board
The reconnection board is located on the
right side of the generator at the rear above
the Load Output Box. The reconnection
board allows reconfiguration from 120 to
208 for low wye and 240 to 416 for high
wye VAC output.
15.2.1.4.4 Muffler
The muffler and exhaust tubing are
connected to the engine’s turbo charger.
The exhaust exits through the top of the
generator set. Gases are exhausted
upward.
15.2.1.4.5 Radiator Fill Bottle
Figure 2-43 – Right side
components of TQG-B generator.
The radiator fill bottle is located on the right
side of the engine. The bottle has hot and cold markings that indicate where the coolant
levels should be during operation when hot and when cold. Only authorized personnel
can add coolant to the engine and only through the fill bottle.
15.2.1.4.6 Serpentine Fan Belt
The serpentine fan belt is located in the engine compartment on the front of the engine.
The fan belt drives several components including the fan, water pump, and batterycharging alternator.
15.2.1.4.7 Water Pump
The water pump is located at the front of the engine. The pump circulates coolant
through the engine block and the radiator.
15.2.1.4.8 Battery Charging Alternator
The battery-charging alternator is located on the right side of the engine. It is capable of
constantly charging the batteries to keep them in a charged state in addition to providing
the required 24 volts to the control circuits. The alternator is protected by an inline fuse
rated at 30 amps located above the fuel tank and below the alternator.
15.2.1.4.9 Oil Filter
The oil filter is in the engine compartment on the left side. The oil filter removes
impurities from the oil.
15.2.1.4.10 Starter
The starter is on the right side of the engine. The starter motor engages the engine’s
flywheel to start the diesel engine.
NAVEDTRA 14027A
2-43
15.2.1.4.11 Crankcase Breather Filter Assembly
The crankcase breather filter assembly is at the right side of the engine compartment.
The filter element removes particles from oil and air contaminants when they pass from
the crankcase to the engine air intake.
15.2.1.4.12 Fuel Filter/Water
Separator
The fuel filter/water separator is
on the right side of the engine
compartment. The element
removes water impurities from
the diesel fuel.
15.2.2 Operation of TQG-B
15.2.2.1 Checklists for the
TQG-B
Checklists exist to give you a
thorough reference for
inspecting the generator set at
various points. The checklists
contain a list of components for
each of the sides of the
generator set that need to be
checked. There are four
checklists for the before
operations check, during
operations check, after
operations check, and parallel
operations check (Figure 2-44).
Figure 2-44 – Checklists utilized for TQG-B
operation.
15.2.2.1.1 Before Operations
Check
It is very important to check the
components and instruments of
the TQG-B before starting it.
Performing the before
operations check will ensure
that the generator is in good
condition to start. The generator
set could be damaged or fail to
start if the before operations
check is not done or is done
incorrectly.
Figure 2-45 gives guidance for a
thorough before operation exam
of the generator. The Before
Operations Checklist covers all
the major components and
NAVEDTRA 14027A
Figure 2-45 – Before Operations Checklist.
2-44
instruments of the generator and is important because it does the following:
•
Reduces the likelihood of damage to the generator.
•
Allows you to identify maintenance issues before they become a problem.
•
Increases the chances of supplying power to those crews that need it when they
need it.
Remember, never attempt to start the generator set unless it is properly grounded. The
generator set produces high voltage when it is in operation, and failure to comply can
result in injury or death to personnel.
15.2.2.1.2 Before Operations Check: Rear
We will now use the pre-operations
checklist to perform the before operations
check. The before operations check is
performed in a 360° rotation that starts at
the rear of the generator (Figure 2-46).
15.2.2.1.2.1 Ground Rod Inspection
First, inspect the ground rod and generator
ground stud to ensure proper grounding.
Remember that failure to ensure proper
grounding may result in death or serious
bodily injury by electrocution.
15.2.2.1.2.2 Housing Inspection
Check the housing, door fasterners, and
hinges. Note that the generator will be
deadlined if the doors are not secure.
Figure 2-46 – Before operations
check – rear.
15.2.2.1.2.3 Identification Plate
Inspection
Check that the identification plates are secured in place.
15.2.2.1.2.4 Indicator and Controls Inspections
Check all indicators and controls for damaged or missing parts. Note that if a
discrepancy exists, the unit is deadlined.
15.2.2.1.2.5 Control Box Harness Inspection
Check the control box harness for loose or damaged wiring. Note that if a discrepancy
exists, the unit is deadlined.
15.2.2.1.2.6 Power Fuse Inspection
Confirm that the dc power control fuse is intact and has a ten amp power rating.
15.2.2.1.2.7 Frequency Selection
Verify that the frequency selection switch is at the correct position for the power you are
providing. For NORMAL the switch should be set to NORMAL sixty hertz. For NATO the
switch should be set to NATO 50 hertz.
NAVEDTRA 14027A
2-45
15.2.2.1.2.8 Cable Inspections
Check the parallel receptacle and parallel cable for damage.
15.2.2.1.2.9 Air Cleaner Element Inspection
Inspect the air cleaner element and assembly for restrictions or damage. The restriction
indicator will tell you whether the air cleaner filter needs changing.
15.2.2.1.3 Before Operations Check: Left Side
Refer to Figure 2-47 for inspection points
associated with before operations check –
left side.
15.2.2.1.3.1 Skid Base Inspection
Inspect the skid base for corrosion and
cracks.
15.2.2.1.3.2 Housing Inspection
Inspect the engine compartment housing,
along with the air ducts and exhaust grills.
You also need to check the door fasteners
and hinges just like you did for the rear of
the generator.
15.2.2.1.3.3 Identification Plate
Inspection
Check that the identification plates are
secured and in place.
Figure 2-47 – Before operations
check – left side.
15.2.2.1.3.4 Engine Compartment Inspection
Inspect the engine compartment for damage.
15.2.2.1.3.5 Engine Compartment Wiring Inspection
Inspect the engine compartment and look for loose or missing components.
15.2.2.1.3.6 Acoustic Material Inspection
Inspect the acoustic material pockets to make sure that all acoustic materials are intact.
15.2.2.1.3.7 Lubrication System Inspection
Check the dipstick to make sure the oil is at the full level. Then inspect the rest of the
lubrication system to make sure there are no leaks. Note that if any class three leaks
exist, the generator will be deadlined.
15.2.2.1.3.8 Fuel System Inspection
Inspect the fuel system for leaks and damaged or missing parts. Note that if any leaks
or other discrepancies exist, the generator will be deadlined.
15.2.2.1.3.9 Cooling Fan Inspection
Make certain the cooling fan is not damaged or loose and is in good working condition.
NAVEDTRA 14027A
2-46
15.2.2.1.3.10 Radiator Cap and Hose Inspection
Inspect the Radiator Cap without removing it. Make sure there are no cracks in the
Radiator Cap or the hoses.
15.2.2.1.4 Before Operations Check:
Front
Refer to Figure 2-48 for inspection points
associated with before operations check –
front side.
15.2.2.1.4.1 Housing Inspection
Inspect the housing, door fasteners, and
hinges just like you did for the rear and left
sides of the generator. Note that the
generator set will be deadlined if the doors
cannot be secured.
15.2.2.1.4.2 Identification Plate
Inspection
Check that the identification plates are
secured and in place.
Figure 2-48 – Before operations
check – front side.
15.2.2.1.4.3 Types of Batteries
Check the battery type to see if they are maintenance free.
15.2.2.1.4.4 Electrolyte Levels
Check the electrolyte level of the batteries if they are not maintenance-free batteries.
15.2.2.1.4.5 Battery Inspection
Check the batteries for any damage or corrosion to the battery terminals and
connections. Make sure the connections are secure. Note that the generator is
deadlined if cables are loose, damaged, or
missing.
15.2.2.1.5 Before Operations Check:
Right Side
Refer to Figure 2-49 for inspection points
associated with before operations check –
right side.
15.2.2.1.5.1 Skid Plate Inspection
Inspect the skid plate for corrosion and
cracks.
Figure 2-49 – Before operations
check – right side.
NAVEDTRA 14027A
2-47
15.2.2.1.5.2 Housing Inspection
Inspect the engine compartment housing, along with the air ducts and exhaust grills.
You also need to check the door fasteners and hinges just like you did for the rear of the
generator.
15.2.2.1.5.3 Identification Plate Inspection
Check that the identification plates are secured and in place.
15.2.2.1.5.4 Engine Compartment Inspection
Inspect the engine compartment for damage.
15.2.2.1.5.5 Engine Compartment Component Inspection
Inspect the engine compartment and look for loose or missing components.
15.2.2.1.5.6 Acoustic Material Inspection
Inspect the acoustic material pockets to make sure that all acoustic materials are intact.
15.2.2.1.5.7 Serpentine Belt Inspection
Check serpentine belt for cracks, fraying, or looseness.
15.2.2.1.5.8 Fuel Filter/Water Separator Inspection
Check the fuel filter and the water separator, and drain off water and other
contaminants.
15.2.2.1.5.9 Radiator Bottle Inspection
Check the radiator bottle for the proper coolant level and for leaks. Note that the
generator will be deadlined if any class three leaks are present. Make sure to add
coolant to the overflow bottle only. Never remove the radiator cap to fill the coolant.
Removing the radiator cap could cause serious burns.
15.2.2.1.5.10 Exhaust System Inspection
Inspect the muffler and exhaust system for corrosion, damage, or missing parts. Note
that the generator is deadlined if a discrepancy exists.
15.2.2.1.5.11 Ether Start System Inspection
Inspect the ether start system and confirm that there are no missing or loose
components.
15.2.2.1.5.12 Output Box Assembly Inspection
Inspect the output box assembly for loose or damaged wiring or cables. Note that if
hardware,cables, or wires are damaged, the unit is deadlined until repairs are made.
15.2.2.1.5.13 Voltage Reconnection Board/Selector Switch Inspection
Ensure that the voltage reconnection board and the voltage selection switch are
positioned correctly.
NAVEDTRA 14027A
2-48
15.2.2.1.6 Precautions Prior to Starting the TQG-B
Now that you have completed the before operations checks using the Pre-Operations
Checklist, you can continue with the controls, sequences, and safety precautions
required to start the TQG-B generator. Other Seabees are relying on the power that you
supply for their safety and their ability to operate necessary equipment. Failing to start
the TQG-B could leave you and your fellow
Seabees in the dark and vulnerable to the
enemy.
15.2.2.1.6.1 Ground Rod Warning
Before learning how to start the TQG-B,
take a moment to read this important safety
warning. It is imperative for you to take this
warning seriously. Remember, never
attempt to start the generator set unless it is
properly grounded. The generator set
produces high voltage when it is in
operation, and failure to comply can result
in injury or death to personnel (Figure 250).
15.2.2.1.6.2 Deadly Gases Warning
It is imperative for you to take this warning
seriously. Never attempt to operate the
generator set in an enclosed area unless
exhaust discharge is properly vented
outside. Exhaust discharge contains deadly
gases, including carbon monoxide. Failure
to comply can cause injury or death to
personnel (Figure 2-51).
Figure 2-50 – Ground rod
warning.
15.2.2.1.7 Starting the TQG-B
Starting the TQG-B is a ten-step process
that you must be able to execute without
the use of a checklist or other aid. Pay
close attention to each step, and you will be
able to start the TQG-B quickly and
correctly. Start-up is conducted as follows:
•
Turn the Dead Crank Switch to the
NORMAL position.
•
Place the Master Control Switch to
the ON position.
•
Ensure the Emergency Stop Switch
is pulled out.
•
Ensure the Battle Short Switch is in the OFF position.
•
Scroll to Display Mode on the CIM and press SELECT using the keypad to
continue to the FULL screen.
NAVEDTRA 14027A
Figure 2-51 – Deadly gases
warning.
2-49
•
Hold the Fault Reset Switch in the ON position and place the Engine Control
Switch in the START position and hold no longer than fifteen seconds or until
engine oil pressure reaches twenty-five PSI. Then release the Fault Reset Switch
and the Engine Control Switch. NOTE: Never hold the Engine Control Switch in
the START position for longer than 15 seconds. If utilizing an auxiliary fuel
source, place the Engine Control Switch to PRIME & RUN AUX FUEL.
•
Scroll to the FULL icon on the Display Mode of the CIM using the keypad and
press SELECT to display all generator set indicators.
•
Adjust the voltage and frequency to the proper values using the Frequency
Adjustment Switch and the Voltage Adjustment Switch.
•
Allow the generator set to run with no load for five minutes for warmup. NOTE:
Damage to the engine can occur if a load is applied before the engine warms up.
•
Place the AC Circuit Interrupter Switch into the CLOSED position. This will apply
energy to the load.
15.2.2.1.8 During Operations Check
It is very important to check some
components of the TQG-B during operation.
Performing the during operations check will
ensure that the generator is running correctly.
The generator set could be damaged if the
during operations check is not done or is done
incorrectly (Figure 2-52).
The checklist gives guidance for a during
operations exam of the generator. The During
Operations Checklist covers all the
components and instruments of the TQG-B
that need to be checked while running. The
During Operations Checklist does the
following:
•
Reduces the likelihood of damage to
the generator.
•
Allows you to identify maintenance
issues before they become a problem.
•
Increases the chances of supplying power to those Seabees that need it when
they need it.
Figure 2-52 – During Operations
Checklist.
Before learning how to perform a during operations check, take a moment to read the
following two safety warnings. It is imperative for you to take each warning seriously. (1)
Remember, never attempt to connect or disconnect load cables while the generator set
is running. High voltage is produced when the generator set is in operation, and failure
to comply can result in injury or death to personnel.
It is imperative for you to take this warning seriously. (2) Remember, personnel must
wear hearing protection when operating or working near the generator set with any
access door open. Failure to comply can cause hearing damage to personnel.
NAVEDTRA 14027A
2-50
15.2.2.1.8.1 During Operations Check: Rear
Now that you have read the warnings you can use the During Operations Checklist to
perform the during operations check. Like other checks, the during operations check is
performed in a 360° rotation that starts at the rear of the generator. Here are the three
steps required to inspect the rear side of the TQG-B when it is running:
•
Visually inspect the ground rod cable and connection for loose or damaged
connections. Do not touch to inspect/check. Do not use if cable is loose or
damaged.
•
Check housing, door fasteners and hinges for damaged, loose, or corroded
items. The generator is deadlined if the doors will not secure.
•
Check all DCS Control Box Assembly indicators to ensure they are operating
properly. If indicators are not operating properly, the CIM is inoperative.
15.2.2.1.8.2 During Operations Check: Left
Now you will learn how to perform the second part of the 360° rotation by inspecting all
necessary components on the left side of the TQG-B. There are six steps to inspect the
left side of the TQG-B:
•
Check the housing, door fasteners and hinges for damaged, loose, or corroded
items. Check air ducts and exhaust grills for debris. The generator is deadlined if
the doors will not secure or the debris cannot be cleared.
•
Check that the engine compartment is not damaged.
•
Check that the engine compartment has no loose or missing components.
•
Check the lubrication system for leaks and damaged, loose, or missing parts. If
any Class III leaks or other discrepancies are present, the generator is deadlined.
•
Check the fuel system for leaks, damaged, loose, or missing parts. Any leaks or
other discrepancies deadline the generator.
•
Check for unusual noise being emitted from the cooling fan area. If the fan is
damaged or loose, the generator is deadlined.
15.2.2.1.8.3 During Operations Check: Front
You have learned how to perform the steps of the during operations check on the rear
and left side of the generator. Now you will learn to inspect the front of the TQG-B.
There is only one step on the during operations check for the front of the generator:
•
Check housing, door fasteners, and hinges for damaged, loose, or corroded
items. The generator is deadlined if the doors will not secure.
15.2.2.1.8.4 During Operations Check: Right Side
You will now learn the final part of the 360° rotation by inspecting all necessary
components on the right side of the TQG-B. There are four steps to inspect the right
side of the TQG-B:
•
Check the housing, door fasteners, and hinges for damaged, loose, or corroded
items. Check air ducts and exhaust grills for debris. The generator is deadlined if
the doors will not secure or the debris cannot be cleared.
•
Check that the engine compartment is not damaged.
NAVEDTRA 14027A
2-51
•
Check that the engine compartment has no loose or missing components.
•
Check the radiator overflow bottle for leaks and missing parts. Generator is
deadlined if a Class III leak is present. The cooling system operates at high
temperature and pressure.
15.2.2.1.9 Shutting Down the TQG-B
Following the seven-step process for shutting down the generator will prevent damage
to vital equipment.
Shutting down the TQG-B is a seven-step
process that you must be able to execute
without the use of a checklist or other aid.
Pay close attention to each step and you
will be able to shut down the TQG-B quickly
and correctly. Refer to Figure 2-53 for
shutdown sequence.
Step 1: Place the AC Circuit Interrupter
Switch into the OPEN position until
contactor on the CIM display
screen reads Open.
Step 2: Allow the engine to operate for
approximately 5 minutes with no
load applied to allow cooling off of
the engine and AC generator.
Step 3: Scroll to EXIT on the CIM and
select. After approximately 5
seconds the engine will stop.
Figure 2-53 – TQG-B generator
shutdown sequence.
Step 4: Place the Master Control Switch into the OFF position when the CIM screen
displays a message that it is safe to turn off the computer.
Step 5: Place the Engine Control Switch into the OFF position.
Step 6: Turn the Panel Light Switch to the OFF position. Note: This step is not
necessary if panel lights are already off.
Step 7: Place the Dead Crank Switch into the OFF position.
15.2.2.1.10 After Operations Checks
It is very important to check the components and instruments of the TQG-B after you
operate it. Performing the after operations check will ensure that the generator is in
good condition for its next use. The generator set could be damaged or fail to start if the
after operations check is not done or is done incorrectly. Refer to Figure 2-54.
The After Operations Checklist gives you guidance for a thorough after operations
inspection of the generator and covers the components and instruments that need
checking after operation. The After Operations Checklist is essential before operation of
the TQG-B because it does the following:
•
Reduces the likelihood of damage to the generator.
•
Allows you to identify maintenance issues.
NAVEDTRA 14027A
2-52
Before learning how to conduct the after operations checks take a moment to read the
following safety warning. It is imperative for
you to take the warning seriously.
Remember: Avoid shorting any positive with
ground/negative. DC voltages are present
at generator set electrical components even
with the generator set shut down. Failure to
comply can cause injury to personnel and
damage to equipment.
15.2.2.1.10.1 After Operations Check:
Rear
The after operations check is performed in
a 360° rotation around the generator. Begin
by inspecting all components at the rear of
the TQG-B. There are nine steps to the
inspection of the rear side of the TQG-B:
•
Figure 2-54 – After Operations
Inspect the ground rod and
generator ground stud to ensure
Checklist.
proper grounding. Failure to ensure
proper grounding may result in death or serious bodily injury by electrocution.
•
Check the housing, door fasteners, and hinges. The generator is deadlined if the
doors will not secure.
•
Check that the identification plates are secured and in place.
•
Check all indicators and controls for damaged or missing parts. If a discrepancy
exists, the unit is deadlined.
•
Check the control box harness for loose or damaged wiring. If a discrepancy
exists, the unit is deadlined.
•
Verify that the dc power control fuse is serviceable with a power rating of 10
AMPS.
•
Verify that the frequency selection switch is positioned correctly. NORMAL - 60
HZ NATO = 50 HZ.
•
Inspect the parallel cable and the cable connections for damage. This cable is
used for parallel operation.
•
Check the air cleaner element or assembly for damage or restrictions. Generator
is deadlined if the exhaust elements are clogged or the piping connections are
loose.
15.2.2.1.10.2 After Operations Check: Left Side
There are ten steps to inspect the left side of the TQG-B:
•
Check that the skid bases are not corroded or cracked.
•
Check the housing, air ducts, exhaust grills, door fasteners, and hinges. The
generator is deadlined if the doors will not secure.
•
Check that the identification plates are secured and in place.
NAVEDTRA 14027A
2-53
•
Check that the engine compartment is not damaged.
•
Check that the engine compartment has no loose or missing components.
•
Check that the acoustical materials are not missing or damaged.
•
Check the lubrication system for leaks, oil level, or oil contamination. If any Class
III leaks are present, the generator is deadlined.
•
Check the fuel system for leaks, and damaged, loose or missing parts. Any leaks
or other discrepancies deadline the generator.
•
Check the cooling fan for damage or looseness. If the fan is damaged or loose,
the generator is deadlined.
•
Check the radiator cap and hoses for cracks and leaks.
15.2.2.1.10.3 After Operations Check: Front
The following five steps are required in performing the after operations check on the
front of the generator:
•
Check the housing, door fasteners, and hinges. The generator is deadlined if the
doors will not secure.
•
Check that the identification plates are secured and in place.
•
Check to see if the unit has maintenance-free batteries. Both batteries need to be
of the same type (maintenance-free or electrolyte--do not mix the two).
Maintenance-free batteries are often recognizable by their lack of fill caps.
•
Check the electrolytes if the unit does not have maintenance-free batteries.
•
Check the batteries for damage or corrosion on connections and cables.
Generator is deadlined if cables are loose, damaged, or missing.
15.2.2.1.10.3 After Operations Check: Right Side
There are 13 steps to inspect the right side of the TQG-B:
•
Check that the skid bases are not corroded or cracked.
•
Check the housing, air ducts, exhaust grills, door fasteners, and hinges. The
generator is deadlined if the doors will not secure.
•
Check that the identification plates are secured and in place.
•
Check that the engine compartment is not damaged.
•
Check that the engine compartment has no loose or missing components.
•
Check that the acoustical materials are not missing or damaged.
•
Check serpentine belt for cracks, fraying, or looseness. Generator is deadlined if
the belt is broken or missing.
•
Check fuel filter/water separator, and drain off water and other contaminants.
•
Check the radiator bottle for leaks and coolant level. Generator is deadlined if a
Class III leak is present. Add coolant to the overflow bottle ONLY. DO NOT
remove the radiator cap.
•
Check muffler and exhaust system for corrosion, damage, or missing parts.
Generator is deadlined if a discrepancy exists.
NAVEDTRA 14027A
2-54
•
Check ether start system for missing or loose hardware.
•
Check the output box assembly for loose or damaged wiring or cables. If
hardware, cables, or wires are damaged, the unit is deadlined until repairs are
made.
•
Verify the voltage reconnection board and the voltage selection switch are
positioned correctly.
16.0.0 PARALLEL OPERATION
If the load of a single generator becomes so large that it exceeds the generator’s rating,
add another generator in parallel to increase the power available for the generating
station. Before two ac generators can be paralleled, the following conditions have to be
fulfilled:
•
Their terminal voltages have to be equal.
•
Their frequencies have to be equal.
•
Their voltages have to be in phase.
When two generators are operating so that the requirements are satisfied, they are said
to be in synchronism. The operation of getting the machines into synchronism is called
synchronizing.
Generating plants may be operated in parallel on an isolated bus (two or more
generators supplying camp or base load) or on an infinite bus (one or more generators
paralleled to a utility grid).
One of the primary considerations in paralleling generator sets is achieving the proper
division of load. That can be accomplished by providing the governor of the generator
with speed droop. That would result in a regulation of the system. The relationship of
REGULATION to LOAD DIVISION is best explained by referring to a speed versus load
curve of the governor. For simplicity, we will refer to the normal speed as 100 percent
speed and full load as 100 percent load. In the controlled system, we will be concerned
with two types of governor operations: isochronous and speed droop.
Figure 2-55 – Isochronous
governor curve.
NAVEDTRA 14027A
Figure 2-56 – Speed droop
governor curve.
2-55
The operation of the isochronous governor (0 percent speed droop) can be explained by
comparing speed versus load (Figure 2-55). If the governor were set to maintain the
speed represented by Line A and connected to an increasing isolated load, the speed
would remain constant. The isochronous governor will maintain the desired output
frequency regardless of load changes if the capacity of the engine is not exceeded.
The speed-droop governor (100 percent speed droop) has a similar set of curves, but
they are slanted (Figure 2-56). If a speed-droop governor were connected to an
increasing isolated load, the speed would drop until the maximum engine capacity was
reached (Figure 2-56, Line A).
Now imagine that you connect the speed droop governor (slave machine) to a utility bus
so large that our engine cannot change the bus frequency (an infinite bus). Remember
that the speed of the engine is no longer determined by the speed setting but by the
frequency of the infinite bus. In this case, if we should change the speed setting, we
would cause a change in load, not in speed. To parallel the generator set you must
have a speed setting on Line A at which the no-load speed is equal to the bus
frequency (Figure 2-56). Once the set is paralleled, if you increase the speed setting to
Line B, you do not change the speed, but you pick up approximately a half-load.
Another increase in speed setting to Line C will fully load the engine. If the generator set
is fully loaded and the main breaker is opened, the no-load speed would be 4 percent
above synchronous speed. This governor would be defined as having 4 percent speed
droop.
Paralleling an isochronous governor to an infinite bus would be impractical because any
difference in speed setting would cause the generator load to change constantly. A
speed setting slightly higher than the bus frequency would cause the engine to go to
full-load position. Similarly, if the speed setting were slightly below synchronous speed,
the engine would go to no load position.
Set speed droop on hydraulic governors by adjusting the speed-droop knob located on
the governor body. Setting the knob to position No. 5 does not mean 5 percent droop.
Each of the settings on the knob represents a percentage of the total governor droop. If
the governor has a maximum of 4 percent droop, the No. 5 position would be 50 percent
of 4 percent droop. Set speed droops on solid-state electronic governors by placing the
UNIT-PARALLEL switch in the PARALLEL position. The governor speed droop is
factory set, and no further adjustments are necessary.
16.1.0 Isolated Bus Operation
In the following discussion, assume that one generator, called the master machine, is
operating and that a second generator, called the slave machine, is being synchronized
to the master machine. Governor controls on the master generator should be set to the
ISOCHRONOUS or UNIT position. The governor setting on the slave generator must be
set to the PARALLEL position.
NOTE
The hydraulic governor droop setting is an approximate value. Setting the knob to
position No. 5 will allow you to parallel and load the generator set. Minor adjustments
may be necessary to prevent load swings after the unit is operational.
When you are paralleling in the droop mode with other generator sets, the governor of
only one set may be in the isochronous position; all others are in the droop position. The
isochronous set (usually the largest capacity set) controls system frequency and
NAVEDTRA 14027A
2-56
immediately responds to system load changes. The droop generator sets carry only the
load placed on them by the setting of their individual speed controls. Both voltage
regulators should be set for parallel and automatic operation.
Bring the slave machine up to the desired frequency by operating the governor controls.
It is preferable to have the frequency of the slave machine slightly higher than that of
the master machine to assure that the slave machine will assume a small amount of
load when the main circuit breaker is closed. Adjust the voltage controls on the slave
machine until the voltage is identical to that of the master machine. Thus two of the
requirements for synchronizing have been met: “frequencies are equal and terminal
voltages are equal.”
There are several methods to check generator phase sequence. Some generator sets
are equipped with phase sequence indicator lights and a selector switch labeled “GEN”
and “BUS.” Set the PHASE SEQUENCE SELECTOR SWITCH in the BUS position, and
the “1-2-3” phase sequence indicating light should light. (The same light must light in
either GEN or BUS position.) If “3-2-1” phase sequence is indicated, shut down the
slave machine, isolate the load cables, and interchange two of the load cables at their
connection to the load terminals.
Another method to verify correct phase sequence is by using the synchronizing lights.
When the synchronizing switch is turned on, the synchronizing lights will start blinking. If
the synchronizing lights blink on and off simultaneously, the voltage sequences of the
two machines are in phase. The frequency at which the synchronizing lights blink on
and off together indicates the different frequency output between the two machines.
Raise or lower the speed of the slave machine until the lights blink on together and off
together at the slowest possible rate. If the synchronizing lights are alternately blinking
(one on while the other is off), the voltage sequence of the two machines is not in
phase. Correct this condition by interchanging any two of the three load cables
connected to the slave machine.
Some of the portable generators being placed in the Table of Allowances (TOA) are
equipped with a permissive paralleling relay. This relay, wired into the main breaker
control circuit, prevents the operator from paralleling the generator until all three
conditions have been met.
Now that all three paralleling requirements have been met, the slave machine can be
paralleled and loaded.
If you use a synchroscope, adjust the frequency of the slave machine until the
synchroscope pointer rotates clockwise slowly through the ZERO position (twelve
o’clock). Close the main circuit breaker just before the pointer passes through the ZERO
position. To parallel using synchronizing lights, wait until the lamps are dark; then, while
the lamps are still dark, close the main circuit breaker and turn off the synchronizing
switch.
After closing the main breaker, check and adjust the load distribution by adjusting the
governor speed control. Maintain approximately one-half load on the master machine by
manually adding or removing the load from the slave machine(s). The master machine
will absorb all load changes and maintain correct frequency unless it becomes
overloaded or until its load is reduced to zero.
The operator also must ensure that all generating sets operate at approximately the
same power factor (PF). PF is a ratio, or percentage, relationship between watts (true
power) of a load and the product of volts and amperes (apparent power) necessary to
supply the load. PF is usually expressed as a percentage of 100. Inductive reactance in
NAVEDTRA 14027A
2-57
a circuit lowers the PF by causing the current to lag behind the voltage. Low PFs can be
corrected by adding capacitor banks to the circuit.
Since the inductive reactance cannot be changed at this point, the voltage control
rheostat has to be adjusted on each generator to share the reactive load. This
adjustment has a direct impact on the generator current, thus reducing the possibility of
overheating the generator windings.
PF adjustment was not discussed in the “Single Plant Operation” section because a
single generator has to supply any true power and/or reactive load that may be in the
circuit. The single generator must supply the correct voltage and frequency regardless
of the PF.
16.2.0 Infinite Bus Operation
Paralleling generator sets to an infinite bus is similar to the isolated bus procedure with
the exception that all sets will be slave machines. The infinite bus establishes the grid
frequency; therefore, the
governor of each slave machine
has to have speed droop to
prevent constant load changes.
16.3.0 Operating
Procedures for
Paralleling
Generators
(General)
This section will include
procedures for paralleling
generators, removing a set from
parallel operations, and stopping
generator set operation.
Operating procedures for
paralleling the TQG-B generator
will be discussed in a separate
section.
NOTE
Figure 2-57 – Parallel operation connection
These procedures assume that
diagram.
one generator set is on line
(operating and connected to the distribution feeder lines through the switchgear). The
set that is to be paralleled is designated the incoming set (Figure 2-57).
CAUTION
When you are operating generator sets in parallel, they must have the same output
voltage, frequency, phase relation, and phase sequence before they can be connected
to a common distribution bus. Severe damage may occur to the generator sets if these
requirements are not met.
Adjusting the engine speed of the incoming set while observing the output frequency
and the SYNCHRONIZING LIGHTS will bring the phase and frequency into exact
agreement (Figure 2-37). As the phase and frequency approach the same value, the
NAVEDTRA 14027A
2-58
SYNCHRONIZING LIGHTS will gradually turn on and off. When the blinking slows to a
rate of once per second or slower, close the main circuit breaker of the incoming set
while the SYNCHRONIZING LIGHTS are dark. The phase sequence relates to the
order in which the generator windings are connected. If the phase sequence is not
correct, the SYNCHRONIZING LIGHTS will not blink on and off together. When the
incoming set is first connected to the load through the appropriate switchgear (Figure 257), you should observe one of four occurrences. When the phase sequence, voltage,
frequency, phase, and engine performance are the same, the changeover will be
smooth with only the slightest hesitation in engine speed; if each output is slightly out of
phase, one of the engines will shudder at the point of changeover; if the phase
sequence or voltage levels are incorrect, the reverse power relay will trip on one of the
generator sets and open its main circuit breaker contactors; if the incoming generator
set loses speed significantly or almost stalls, the incoming engine may be defective.
CAUTION
Should either generator set lose speed, buck, or shudder when the incoming set is
connected to the distribution feeder lines, immediately flip the CKT BRK switch of the
incoming set to open, and then recheck the paralleling setup procedures.
WARNING
When performing Step 1, make certain that the incoming set is shut down and that there
are no voltages at the switchgear terminals being connected to the incoming set. Do not
take anybody’s word for it! Check it out for yourself! Dangerous and possibly deadly
voltages could be present. Take extreme care not to cross the L0 (neutral) with any of
the other phases (L1, L2, or L3).
16.3.1 Paralleling Procedures (General)
1. Connect the incoming set as shown in Figure 2-57
2. Make certain that the voltage change board (reconnection board) of the incoming
generator is set up for the same output voltage as the online generator.
3. Set CKT BRK switch on the incoming set to OPEN. When the incoming set circuit
breaker is open (CKT BRK indicator light will be out), operate the load switchgear
so that the on line output voltage is present at the voltage change board of the
incoming set.
4. Set the PARALLEL OPERATION-SINGLE UNIT operation switch on both sets to
PARALLEL OPERATION.
5. Start the incoming set. The on line set should be in operation already.
6. After a 5-minute warmup, try the VOLTAGE ADJUST control on the incoming set
until the output voltages of both sets are equal.
CAUTION
If the synchronizing lights do not blink on and off in unison, the phase sequence is
incorrect. Shut down the incoming set and recheck the cabling to and from the incoming
set.
7. On the incoming set, position the ENGINE MANUAL SPEED CONTROL until the
SYNCHRONIZING LIGHTS blink on and off as slowly as possible.
NAVEDTRA 14027A
2-59
8. With one hand on the CKT BRK switch, adjust the ENGINE MANUAL SPEED
CONTROL vernier knob until the SYNCHRONIZING LIGHTS dim gradually from
full on to full off as slowly as possible. Just as the SYNCHRONIZING LIGHTS
dim to out, set and hold the CKT BRK switch to close. When the CKT BRK
indicator light comes on, release the switch.
9. On both sets, check that the readings of the PERCENT RATED CURRENT
meters and KILOWATTS meters are well within 20 percent of each other. If not,
increase the engine power of the set with the lower readings (by adjusting the
ENGINE MANUAL SPEED CONTROL to increase the speed) until the readings
are about equal.
NOTE
The division of the kilowatt load is also dependent on the frequency droop of the two
sets and must be adjusted at the next higher level of maintenance. If the current does
not divide as described above, adjust the reactive current sharing control located at the
right side of the special relay box for equal reading on both percent rated current
meters.
10. On the incoming set, readjust the voltage and frequency of the output until it is
equal to the output of the on line set.
16.3.2 Removing a Generator Set from Parallel Operation (General)
CAUTION
Before removing the generator set(s) from parallel operation, make sure the load does
not exceed the full-load rating of the generator set(s) remaining on the line.
1. On the outgoing set, position and hold the CKT BRK switch to OPEN until the
CKT BRK indicator light goes out. Release the switch.
2. On the outgoing set, allow the engine to operate with no load for about 5
minutes.
3. On the outgoing set, pull the DC CONTROL CIRCUIT BREAKER to OFF.
4. On the outgoing set, set the START-STOP-RUN switch to STOP.
WARNING
Make certain the outgoing set is shut down and there are no voltages at the switchgear
terminals connected to the outgoing set. Do not take anybody’s word for it! Check it out
for yourself!
5. Disconnect the cables going from the outgoing set to the load switchgear.
16.3.3 Stopping Generator Set Operation (General)
1. Set the CKT BRK switch to OPEN until the CKT BRK indicator light goes out, and
then release the CKT BRK switch.
2. Allow the engine to cool down by operating at no load for 5 minutes.
3. Set the START-STOP-RUN switch to STOP.
4. Close all generator doors.
NAVEDTRA 14027A
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16.3.4 Emergency Shutdown
In the event of engine over speed, high jacket water temperature, or low lubricating oil
pressure, the engine may shut down automatically and disconnect from the main load
by tripping the main circuit breaker. In addition, an indicator may light or an alarm may
sound to indicate the cause of shutdown. After an emergency shutdown and before the
engine is returned to operation, investigate and correct the cause of the shutdown.
NOTE
It is important to check the safety controls at regular intervals to determine that they are
in good working order.
16.4.0 Operating the TQG-B in Parallel
It is very important to check components and indicators of the TQG-Bravo before
operating in parallel. Performing the parallel operations check will ensure that both
generators are paralleled without damaging equipment or injuring personnel.
16.4.1 Importance of the Parallel Operations Checklist
The Parallel Operations Checklist covers all
the components and instruments of the
TQG-B that need to be checked before
paralleling. It also guides you through the
process of paralleling two generator sets
(Figure 2-58). The Parallel Operations
Checklist is important because it does the
following:
•
Reduces the likelihood of damage to
the generator.
•
Guides you through the process of
paralleling two generator sets.
Before learning how to perform a parallel
operations check, take a few moments to
read this important safety warning. It is
imperative for you to take this warning
Figure 2-58 – Parallel Operations
seriously. Remember to make sure there is
Checklist.
no input to the load output terminal board
and the generator sets are shut down before making any connections for parallel
operation or moving a generator set which has been operating in parallel. Failure to
comply can cause injury or death to personnel by electrocution.
16.4.2 Parallel Operations Check
Now that you have read the safety warning you are ready to use the Parallel Operations
Checklist to perform the parallel operations check. The parallel operations check will
prepare and start the generators, then apply power from both generators to the load.
There are eighteen steps total on the Parallel Operations Checklist, which have broken
up into two groups. Begin with the first four steps which prepare the generator for
parallel operations. These four steps are to be performed in sequence. Refer to Figure
2-58 for sequence.
NAVEDTRA 14027A
2-61
Step 1: Make sure that both generators are
the same model. Examples would
be two 805 bravos, 806 bravos,
815 bravos, or 816 bravos. Never
try to parallel two different models
of generators.
Step 2: Conduct a before operations check
using the Pre Operations Checklist
on each generator set.
Step 3: Verify the frequency selection
switch is set to NORMAL, 60 hertz
if you are operating at normal
frequency and NATO 50 hertz if
operating at NATO frequency.
Step 4: Verify that the voltage selection
switch of each generator was
positioned correctly during setup.
The last part of the Parallel Operations
Checklist provided steps for preparing the
generators for parallel. The next part guides
you through the procedures for achieving
parallel operations for the two generator
sets. Refer to Figure 2-60 for sequence.
Figure 2-59 – Parallel operations
checks.
Step 5: Designate Set #1.
Step 6: Designate Set #2.
Step 7: Verify that the load cable is rated at
an amperage high enough to
handle maximum load. The TQGBravo model’s highest amperage is
208 Amps.
Step 8: Connect the parallel cable to each
parallel receptacle and connect the
load cables to each load stud on
each generator load terminal
board.
Figure 2-60 – Parallel operations
sequence.
Step 9: Verify that both generators are
connected to the power distribution system.
Step 10: Conduct the 10-step starting procedures for both generators.
Step 11: Verify that the CIM on each generator is displaying the FULL mode screen.
Step 12: Adjust Set #1 to the proper voltage, and then adjust Set #2 to the same
voltage as Set #1.
Step 13: Adjust Set #1 to the proper frequency and then adjust Set #2 to the same
frequency as Set #1. Carefully adjust the frequency; too much adjustment can
cause the generator to go into reverse power.
Step 14: Close AC CIRCUIT INTERRUPT switch on Set #1 and on Set #2. The
generators are now running in parallel with no load.
NAVEDTRA 14027A
2-62
Step 15: Verify that the POWER gauge on both sets reads “zero.”
Step 16: Close the circuit breaker on the power distribution system. The generators are
now supplying power to the load.
Step 17: Verify that the GEN CURRENT indicators on BOTH generators are
approximately the same. If not, adjust the VOLTAGE ADJUST switch up or
down to achieve the proper balance. One generator may have to be adjusted
upward, while the other may have to be adjusted downward.
Step 18: Verify that POWER readings from both CIM displays are within 10% of each
other. If readings are not within 10% of each other, remove generators from
load, shut down, and notify the next level of maintenance.
17.0.0 BALANCING the LOAD
Once you have installed the branch circuit conductors and breakers, you must balance
the load. Conductors cannot be connected to a panelboard by attaching each one as
you come to it. The arrangement or sequence of attaching conductors to the panelboard
is determined by the arrangemet of the bus bars in the panelboard, whether the circuits
are 240 volts or 120 volts, and the need to balance the load on the phase conductors.
Bus bars are installed into panelboards in one of several ways. Most of the time, the bus
bars are run in a vertical configuration. In one arrangement, a split-bus panelboard is
used that has all the 240-volt circuits in the upper section and the 120-volt circuits in a
lower section. Another type of split-bus panelboard uses one main circuit breaker to
feed one set of branch circuits and a second main circuit breaker to feed a second set.
In many cases, panelboards are designed so that any two adjacent terminals can be
used to provide 240-volt service. This arrangement also means that two 120-volt circuits
attached to adjacent terminals are connected to different phase conductors. Since there
are so many panelboard layouts, you must look at the panelboard to see how it is set up
for 240-volt service, and you must be sure you get the conductors for 240- volt circuits
connected to the proper terminals.
Loads that are connected to a panelboard should be divided as evenly as possible
between the supply conductors. This process of equalizing the load is commonly
referred to as load balancing. The purpose of load balancing is to reduce voltage drop
that results from overloading one side of the incoming service. It also prevents the
possibility of overloading the neutral. A perfectly balanced load between the supply
conductors reduces current flow in the neutral to zero.
Load balancing is no problem for 240-volt circuits on a three wire, single-phase system
since the load has to be equal on each phase conductor. However, the 120-volt circuits
are a different matter. These must be connected in such a way that the loads tend to
equalize. Generally speaking, the simplest way to balance the load on a panelboard is
to connect an equal number of branch circuits to each phase conductor. But this method
does not necessarily give you a balanced load as will be evident if you look at the top of
Figure 2-61. As you can see, the indiscriminate connection of branch circuits without
consideration of their loads can cause you to end up with an unbalanced condition. On
the other hand, you can connect the circuits so that one with a heavy load is offset by
one with a light load, which does result in the balanced condition shown at the bottom of
Figure 2-61. Most of the time, you should be able to connect half of the lighting circuits
and half of the appliance circuits to each phase conductor to give you a reasonably well
balanced load. Spare circuits should also be equalized. There is one more thing to
consider and that is when there are appliance circuits where the loads are known to be
heavy, these circuits must be divided between the phase conductors.
NAVEDTRA 14027A
2-63
NAVEDTRA 14027A
Figure 2-61 – Load balancing.
2-64
18.0.0 MAINTAINING FREQUENCY
The output frequency of alternator voltage depends upon the speed of rotation of the
rotor and the number of poles. The faster the speed, the higher the frequency. The
lower the speed, the lower the frequency. The more poles there are on the rotor, the
higher the frequency is for a given speed. When a rotor is rotated through an angle such
that two adjacent rotor poles (a north and a south pole) have passed one winding, the
voltage induced in that winding will have varied through one complete cycle. For a given
frequency, the more pairs of poles there are, the lower the speed of rotation. This
principle is illustrated in Figure 2-62; a two-pole generator must rotate at four times the
speed of an eight-pole generator
to produce the same frequency
of generated voltage.
The frequency of an ac
generator in hertz (HZ), which is
the number of cycles per
second, is related to the number
of poles and the speed of
rotation, as expressed by the
equation:
F=
NP
120
Where P is the number of poles,
N is the speed of rotation in
revolutions per minute (rpm),
and 120 is a constant to allow
for the conversion of minutes to
seconds and from poles to pairs
of poles. For example, a 2-pole,
3600-rpm alternator has a
frequency of 60 HZ and is
determined as follows:
Figure 2-62 — Frequency regulation.
2 × 3600
= 60 H Z
120
A 4-pole, 1800-rpm generator also has a frequency of 60 HZ. A 6-pole, 500-rpm
generator has a frequency of:
6 × 500
= 25 H Z
120
A 12-pole, 4000-rpm generator has a frequency of:
12 × 4000
= 400 H Z
120
The above statements about frequency regulation are general in nature. The TQG-B
generator is designed with a frequency select switch (Figure 2-40), and once frequency
is set it is automatic and will need adjustment only if a fluctuation of voltage takes place.
Remember that the TQG-B generator can be set between 50 and 60 HZ.
NAVEDTRA 14027A
2-65
19.0.0 MAINTAINING VOLTAGE
It has been stated previously in this chapter that when the load on a generator is
changed, the terminal voltage varies. The amount of variation depends on the design of
the generator.
The voltage regulation of an alternator is the change of voltage from full load to no load,
expressed as a percentage of full-load volts, when the speed and dc field current are
held constant.
EηL − E fL
E fL
× 100 = Percent of regulation
Assume the no-load voltage of an alternator is 250 volts and the full-load voltage is 220
volts. The percent of regulation is:
250 − 220
× 100 = 13.6 Percent
220
Remember, the lower the percent of regulation, the better it is in most applications.
19.1.0 Principles of AC Voltage Control
In an alternator, an alternating voltage is induced in the armature windings when
magnetic fields of alternating polarity are passed across these windings. The amount of
voltage induced in the windings depends mainly on three things:
•
Number of conductors in series per winding
•
Speed (alternator rpm) at which the magnetic field cuts the winding
•
Strength of the magnetic field
Any of these three factors could be used to control the amount of voltage induced in the
alternator windings
The number of windings is fixed when the alternator is manufactured. Also, if the output
frequency is required to be of a constant value, then the speed of the rotating field must
be held constant. This prevents the use of the alternator rpm as a means of controlling
the voltage output. The only practical method for obtaining voltage control is to control
the strength of the rotating magnetic field. The strength of this electromagnetic field may
be varied by changing the amount of current flowing through the field coil. This is
accomplished by varying the amount of voltage applied across the field coil.
The above statements concerning voltage control are general in nature. The TQG-B
generator has a voltage regulation system which consists of the automatic voltage
regulator and power potential transformer. The automatic voltage regulator senses and
controls generator output voltage, which is operator adjustable within the design limits
by use of the voltage adjust switch (Figure 2-40). The power potential transformer
provides operating power to the automatic voltage regulator module. Generator output
voltage is indicated on the CIM display screen.
20.0.0 DEMAND FACTOR
As previously mentioned, you must take various factors into consideration in selecting
the required generating equipment.
NAVEDTRA 14027A
2-66
Before designing any part of the system, you must determine the amount of power to be
transmitted, or the electrical load. Electrical loads are generally measured in terms of
amperes, kilowatts, or kilovoltamperes. In general, electrical loads are seldom constant
for any appreciable time, but fluctuate constantly. To calculate the electrical load,
determine the connected load first. The connected load is the sum of the rated
capacities of all electrical appliances, lamps, motors, and so on, connected to the wiring
of the system. The maximum demand load is the greatest value of all connected loads
that are in operation over a specified period of time. Knowledge of the maximum
demand of groups of loads is of great importance because the group maximum demand
determines the size of generators, conductors, and apparatuses throughout the
electrical system.
The ratio between the actual maximum demand and the connected load is called the
demand factor. If a group of loads were all connected to the supply source and drew
their rated loads at the same time, the demand factor would be 1.00. There are two
main reasons why the demand factor is usually less than 1.00. First, all load devices are
seldom in use at the same time and, even if they are, they will seldom reach maximum
demand at the same time. Second, some load devices are usually slightly larger than
the minimum size needed and normally draw less than their rated load. Since maximum
demand is one of the factors determining the size of conductors, it is important to
establish the demand factor as closely as possible.
The demand factor varies considerably for different types of loads, services, and
structures. The National Electrical Code®, Article 220 provides the requirements for
determining demand factors. Demand factors for some military structures are given in
Table 2-1.
Table 2-1 – Demand Factor.
Structure
Demand Factor
Housing
0.9
Aircraft Maintenance Facilities
0.7
Operation Facilities
0.8
Administrative Facilities
0.8
Shops
0.7
Warehouses
0.5
Medical Facilities
0.8
Theaters
3.0
NAV Aids
0.5
Laundry, Ice Plants, and Bakeries
1.0
All others
0.9
Example: A machine shop has a total connected load of 50.3 kilowatts. The demand
factor for this type of structure is taken at 0.70. The maximum demand is 50.3 x 0.70 =
35.21 kilowatts.
NAVEDTRA 14027A
2-67
21.0.0 POWER FACTOR
The power factor is a number (represented as a decimal or a percentage) that
represents the portion of the apparent power dissipated in a circuit. If you are familiar
with trigonometry, the easiest way to find the power factor is to find the cosine of the
phase angle (θ). The cosine of the phase angle is equal to the power factor. You do not
need to use trigonometry to find the power factor. Since the power dissipated in a circuit
is true power, then:
Apparent Power x PF = True Power. Therefore, PF =
True Power
.
Apparent Power
If true power and apparent power are known you can use this formula. Going one step
further, another formula for power factor can be developed. By substituting the
equations for true power and apparent power in the formula for power factor, you get:
PF =
(I R ) 2 R
(I Z ) 2 Z
Since current in a series circuit is the same in all parts of the circuit, I R equals I Z .
R
Therefore, in a series circuit, PF = .
Z
For example, to compute the power factor for the series circuit shown in Figure 2-63,
any of the above methods may be used.
Given:
True Power = 1,500 V
Apparent Power = 2,500 VA
Solution:
PF =
True Power
Apparent Power
PF =
1,500 W
2,500 VA
PF = .6
Another method:
Given:
R = 60 Ω
Z = 100 Ω
Solution:
PF =
R
Z
PF =
60 Ω
100 Ω
PF = .6
NOTE
As stated earlier, the power factor can be expressed as a decimal or percentage. In the
examples above the decimal number .6 could be expressed as 60%.
NAVEDTRA 14027A
2-68
22.0.0 POWER FACTOR CORRECTION
The apparent power in an ac circuit has
been described as the power the source
“sees.” As far as the source is concerned,
the apparent power is the power that must
be provided to the current. You also know
that the true power is the power actually
used in the circuit. The difference between
apparent power and true power is wasted
because, in reality, only true power is
consumed. The ideal situation would be for
apparent power and true power to be equal.
If this were the case the power factor would
be 1 (unity) or 100 percent. There are two
ways in which this condition can exist: (1) if
the circuit is purely resistive or (2) if the
circuit “appears” purely resistive to the
source. To make the circuit appear purely
resistive there must be no reactance. To
have no reactance in the circuit, the
inductive reactance (XL) and capacitive
reactance (XC) must be equal.
Figure 2-63 – Example circuit for
determining power.
Remember: X = X L − X C , therefore when X L = X C X = 0 . The expression “correcting
the power factor” refers to reducing the reactance in a circuit. The ideal situation is to
have no reactance in the circuit. This is accomplished by adding capacitive reactance to
a circuit which is inductive and inductive reactance to a circuit which is capacitive. For
example, the circuit shown in Figure 2-63 has a total reactance of 80 ohms capacitive
and the power factor was .6 or 60 percent. If 80 ohms of inductive reactance were
added to this circuit (by adding another inductor), the circuit would have a total
reactance of zero ohms and a power factor of 1 or 100 percent. The apparent and true
power of this circuit would then be equal.
23.0.0 VOLTAGE DROP
Voltage drop becomes important in industrial areas in which long runs of conductors are
supplying large (ampacity) loads. Excessive voltage drop can cause overheating of
breakers, conductors, and appliancies, creating a safety hazard.
Conductors for a branch circuit should be sized to prevent a voltage drop exceeding 3
percent at the farthest outlet of power, heating, or lighting load. Conductors supplying a
feeder circuit should also be sized to prevent a voltage drop exceeding 3 percent at the
farthest outlet.
Total voltage drop consists of the voltage drop in the feeder plus the voltage drop in the
branch circuit. The maximum voltage drop of a combination feeder/branch circuit should
not exceed 5 percent. The conductors of the feeder should be sized to prevent a voltage
drop of more than 2 percent, and the conductors of the branch circuit should be sized to
prevent a voltage drop exceeding 3 percent.
The basic formula for determining voltage drop in a circuit is as follows:
NAVEDTRA 14027A
2-69
VD =
2× r × L× I
CM
Where:
VD = voltage drop
r = resistivity for conductor material :
Alu min um = 18 ohms per CM − ft
Copper = 12 ohms per CM − ft
L = one − way length of circuit conductor in feet
I = current in conductor in amperes
CM = conductor area in circular mils
The following i s a sa mple problem t o help y ou under stand better w hat has been
discussed: Determine the voltage drop in a 230-volt, two-wire heating circuit. The load is
50 amps. The conductor size is No. 6 AWG THW copper, and the one-way circuit length
is 150 feet.
VD =
2 × 12 × 150 ft × 50 180,000
=
= 6.86 V
26,240
26,240
The m aximum v oltage dr op i s 5 percent o f 240 v olts, or 1 2 v olts. A 6. 86-volt dr op i s
within the acceptable percentage. If the voltage drop had ex ceeded 5 per cent, a l arger
size conductor would have to be used or the circuit length shortened.
24.0.0 HUNTING
Hunting is the sustained oscillation of the rotor following a change in load. The
synchronizing torque TS and the rotor moment of inertia J of the synchronous machine
are analogous to the stiffness and mass of a spring-mass mechanical system. When
subjected to an external disturbance, the load angle follows a simple harmonic motion
TS
and the natural frequency of oscillation is given by ω n =
J
If the driving torque provided by the prime mover is cyclic with a frequency close to ω n ,
hunting may develop into vigorous rotor swings, with a consequent danger of instability.
In practice, some of the rotor energy is dissipated in the stator and field resistances;
hence the oscillations will die down and the synchronous machine will settle to steady
state again after a disturbance. A damper winding may be fitted to the pole surfaces of
the salient-pole synchronous machine to prevent hunting and to improve stability. The
TQG-B is automatic and is a synchronous machine.
NAVEDTRA 14027A
2-70
Summary
Your knowledge, understanding, and application of the material presented in this
chapter concerning power generation are very important to the Seabee community as a
whole. As a Construction Electrician, you need the knowledge of the type of generators
used and how to set up a power generating plant. During your career as a Construction
Electrician, you will apply what has been presented in this chapter in your everyday
conduct. You and your crew’s safety will depend upon your knowledge of proper power
generation and distribution whether in homeport or on deployment.
Remember that generators play an important part in everyday life of the Seabee. The
power that you and your crew produce affects everyone’s work whether you are
operating a generator as a main power source or as standby power in an emergency.
NAVEDTRA 14027A
2-71
Review Questions (Select the Correct Response)
1.
What rule is used to determine the direction of current in a given situation in an
external circuit to which the voltage is applied?
A.
B.
C.
D.
2.
(True or False) Field excitation occurs when a dc voltage is applied to the field
windings of a dc generator, and current flows through the windings and sets up a
steady magnetic field.
A.
B.
3.
stops
increases
decreases
varies
Which of the following field windings does it take to make a compound-wound
generator?
A.
B.
C.
D.
6.
Armature
Self-excited
Compound wound
Parallel
A series-wound dc generator has the characteristic that the output voltage
________ with the load current.
A.
B.
C.
D.
5.
True
False
What term is used to describe a generator that supplies its own field excitation?
A.
B.
C.
D.
4.
Left-hand
Right-hand
Ohm’s law
Henry’s law
Self-excited
Series
Shunt
Both A and B
(True or False) Sparking between the brushes and the commutator is an
indication of improper commutation.
A.
B.
True
False
NAVEDTRA 14027A
2-72
7.
When you are performing an inspection of the armature winding what should be
the first test?
A.
B.
C.
D.
8.
Which material can be used to make slip rings used on rotors?
A.
B.
C.
D.
9.
True
False
What are the names of the two types of rotors used in rotating-field alternators?
A.
B.
C.
D.
13.
Exciter
Shunt field
Commutator
Stator
(True or False) A typical rotating-field ac generator consists of an alternator and
a smaller dc generator built into a single unit.
A.
B.
12.
True
False
In a dc generator the emf generated in the armature windings is converted from
ac to dc by what means?
A.
B.
C.
D.
11.
Steel
Stainless steel
Iron
Bronze
(True or False) All electrical generators, whether dc or ac, depend upon the
principle of magnetic induction.
A.
B.
10.
Open circuit
Grounded circuit
Color
Burn
Turbine-driven and salient-pole
Manual-driven and salient-pole
Wound-pole and salient-pole
Wound-pole and turbine-driven
How are alternators rated?
A.
B.
C.
D.
Voltage produced and maximum current they can provide
Voltage produced only
Maximum current they can provide only
Maximum heating loss that can be sustained only
NAVEDTRA 14027A
2-73
14.
What name is given to a generator that produces a single, continuously
alternating voltage?
A.
B.
C.
D.
15.
How many single-phase windings does a three-phase alternator contain?
A.
B.
C.
D.
16.
10
20
25
30
Which of the following is an acceptable grounding method for a generator set?
A.
B.
C.
D.
20.
True
False
What is the minimum distance,in feet, that a generator should be is set up from a
load?
A.
B.
C.
D.
19.
Wye
Delta
Loop
Charlie
(True or False) The output frequency of alternator voltage depends upon the
speed of rotation of the the rotor and one pole.
A.
B.
18.
2
3
4
5
When a three-phase stator is connected to a three-phase alternator so that the
phases are connected end-to-end, it is called a _________ connection.
A.
B.
C.
D.
17.
Multiphase alternator
Polyphase alternator
Single-phase alternator
None of the above
Underground metallic water piping system
Driven metal rod
Buried metal plate
All of the above
What minimum size AWG copper wire must be used for a ground lead?
A.
B.
C.
D.
2
3
4
6
NAVEDTRA 14027A
2-74
21.
The National Electri9cal Code® states that a single electrode consisting of a rod,
pipe, or plate that does not have a resistance to ground of _____ ohms or less
will be augmented by additional electrodes.
A.
B.
C.
D.
22.
What percent of rated generator amperes should a feeder conductor be capable
of carrying to eliminate overloading and voltage drop problems?
A.
B.
C.
D.
23.
True
False
How many minutes should you allow a generator set to warm-up prior to applying
a load if it is not an emergency situation?
A.
B.
C.
D.
27.
Maintain the equipment.
Keep the operator’s log.
Produce power in a safe and responsible manner.
Keep power plant area clean.
(True or False) As the plant supervisor you should establish a prestart checklist
for each generating plant.
A.
B.
26.
True
False
What is the primary purpose of the generator watch?
A.
B.
C.
D.
25.
75
100
125
150
(True or False) The load cable must be installed underground only.
A.
B.
24.
25
30
40
50
1
3
5
10
At what time interval, at minimum, should you monitor the generator set when it
is in operation for signs indicating possible future malfunctions?
A.
B.
C.
D.
Every hour
Every two hours
Every eight hours
Every day
NAVEDTRA 14027A
2-75
28.
What type engine does the Tactical Quiet Generator (TQG) Bravo model have?
A.
B.
C.
D.
29.
(True or False) The TQG-B and TQG-A can be run in parallel.
A.
B.
30.
Housing door fasteners and hinges
Identification plate
Ground rod and generator ground stud
Indicators and controls
(True or False) The TQG-B generator can be operated in enclosed areas
without exhaust discharge venting.
A.
B.
34.
(a) 1 (b) dry cell
(a) 2 (b) dry cell
(a) 1 (b) 12-volt dc maintenance-free
(a) 2 (b) 12-volt dc maintenance-free
When conducting the before operations checks, what should be your first
inspection?
A.
B.
C.
D.
33.
Front
Rear
Right side
Left side
The TQG-B has (a) how many, and (b) what type batteries?
A.
B.
C.
D.
32.
True
False
Where is the digital control system (DCS) located on the TQG-Bravo?
A.
B.
C.
D.
31.
Briggs and Stratton 480 Gasoline
Cummings 3500 Diesel
John Deere JP-8 Diesel
Murray-Ohio JP-6 Diesel
True
False
When starting the TQG-B turn the Dead Crank Switch to the __________
position.
A.
B.
C.
D.
ON
OFF
NORMAL
RUN
NAVEDTRA 14027A
2-76
35.
What is the purpose of the During Operations Checklist for the TQG-B?
A.
B.
C.
D.
36.
When you are shutting down the TQG-B, in what position must the Master
Control Switch be placed?
A.
B.
C.
D.
37.
True
False
Concerning frequency of a generator, which of the following statements, if any, is
correct?
A.
B.
C.
D.
41.
Achieving the proper division of the load
Achieving overall proper power
Achieving 50 percent load to each generator set
None of the above
(True or False) Loads that are connected to a panelboard should be divided as
evenly as possible between the supply conductors.
A.
B.
40.
Their terminal voltages have to be equal.
Their frequencies have to be equal.
Their voltages have to be in phase.
All of the above
What, if any, of the following is the primary consideration in paralleling generator
sets?
A.
B.
C.
D.
39.
ON
OFF
NORMAL
RUN
Before two ac generators can be paralleled, which of the following conditions
have to be fulfilled?
A.
B.
C.
D.
38.
Reduces the likelihood of damage to the generator.
Allows you to identify maintenance issues before they become a problem.
Increases the chances of supplying power to those Seabees that need it
when they need it.
All of the above
The slower the speed, the higher the frequency.
The faster the speed, the higher the frequency.
The faster the speed, the lower the frequency.
None of the above
(True or False) The voltage regulation of an alternator is the change of voltage
from full load to no load, expressed as a percentage of full-load volts, when the
speed and dc field current are held constant.
A.
B.
True
False
NAVEDTRA 14027A
2-77
42.
Which of the following terms are generally used to measure electrical loads?
A.
B.
C.
D.
43.
(True or False) The power factor is a number that can be represented by either
a decimal or a percentage.
A.
B.
44.
True
False
What does the expression “correcting the power factor” refer to?
A.
B.
C.
D.
45.
Amperes
Kilowatts
Kilovoltamperes
All of the above
No reactance in a circuit
No more than 50% reactance in a circuit
Reducing the reactance in a circuit
Adding reactance in a circuit
What is the maximum allowable percentage for a voltage drop of a combination
feeder/branch circuit and should not be exceeded?
A.
B.
C.
D.
2
3
4
5
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Trade Terms Introduced in This Chapter
Armature
The loop of wire that rotates through the field is called
the armature.
Slip rings
The ends of the armature loop are connected to rings
called slip rings.
Commutator
The two segments of the split metal ring are insulated
from each other. This forms a simple commutator.
Ripple
The voltage developed across the brushes is pulsating
and unidirectional (in one direction only). It varies twice
during each revolution between zero and maximum.
This variation is called ripple.
Residual magnetism
Self-excitation is possible only if the field pole pieces
have retained a slight amount of permanent magnetism,
called residual magnetism.
Field excitation
When a dc voltage is applied to the field windings of a
dc generator, current flows through the windings and
sets up a steady magnetic field and is know as fieldexcitation.
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Additional Resources and References
This chapter is intended to present thorough resources for task training. The following
reference works are suggested for further study. This is optional material for continued
education rather than for task training.
NAVEDTRA 14026A Construction Electrician Basic
NAVEDTRA 14174 Navy Electricity and Electronics Training Series, Module 5
National Electrical Code® (NEC) 2008
Marine Corps TM 09244B/09245B-14/1 Technical Manual Operator, Unit, Direct
Support and General Support Maintenance Manual for Generator Set, Skid Mounted,
Tactical Quiet
NAVEDTRA 14027A
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CSFE Nonresident Training Course – User Update
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NAVEDTRA 14027A
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