DC Generator Voltage Regulation Exam
Questions with Correct Answers
(VerifiedAnswers) Plus Rationales 2026 Q&A
Instant Download PD
Question 1
What is the primary purpose of voltage regulation in a DC
generator?
A. To increase the mechanical speed of the generator
B. To reduce the generator's physical size
C. To maintain the terminal voltage within an acceptable range
as load changes
D. To eliminate all armature resistance
Rationale: Voltage regulation describes the ability of a DC
generator to maintain a relatively constant terminal voltage
when the load changes. As load current increases, internal
voltage drops caused by armature resistance and other effects
tend to reduce terminal voltage. A well-regulated generator
minimizes this change through appropriate design and
excitation. Mechanical speed and physical dimensions are not
the primary purposes of voltage regulation.
,Question 2
Which equation is commonly used to express the generated
EMF of a DC generator?
A. (E_g = V + I_aR_L)
B. (E_g = V/I_a)
C. (E_g = \frac{P\Phi ZN}{60A})
D. (E_g = I_aR_a)
Rationale: The generated EMF of a DC generator is given by
(E_g = P\Phi ZN/(60A)), where (P) is the number of poles, (\Phi)
is flux per pole, (Z) is the total armature conductors, (N) is speed
in revolutions per minute, and (A) is the number of parallel
paths. This equation shows that generated voltage depends
directly on flux and speed, while the winding configuration
affects the number of parallel paths.
Question 3
A DC generator produces an internal generated EMF of 250 V. If
its terminal voltage under load is 240 V, what is the internal
voltage drop?
A. 5 V
B. 10 V
,C. 20 V
D. 25 V
Rationale: The internal voltage drop is the difference between
generated EMF and terminal voltage. Therefore, (250 - 240 =
10) V. This difference represents the combined effects of internal
voltage drops such as armature resistance, brush contact
effects, and other machine losses that influence the voltage
available at the terminals.
Question 4
Which component of a DC generator is primarily responsible for
producing the magnetic field?
A. Commutator
B. Armature conductor
C. Field winding
D. Brush holder
Rationale: The field winding establishes the main magnetic field
in a conventional wound-field DC generator. Current through
the field winding creates magnetomotive force, which produces
magnetic flux. The armature interacts with this flux to generate
EMF. The commutator and brushes primarily provide
mechanical rectification and electrical connection rather than
creating the principal magnetic field.
, Question 5
What happens to the terminal voltage of a separately excited
DC generator when load current increases, assuming excitation
and speed remain constant?
A. It always increases substantially
B. It remains exactly constant
C. It generally decreases
D. It becomes zero immediately
Rationale: Increasing load current increases the voltage drop
across the armature resistance and brush contact resistance. In
addition, armature reaction can weaken or distort the main
magnetic field. Consequently, the generated and terminal
voltage available to the load generally decreases as load current
increases.
Question 6
Which expression most directly represents the terminal voltage
of a DC generator when brush voltage drop is neglected?
A. (V = E_g + I_aR_a)
B. (V = E_g - I_aR_a)
C. (V = I_a/R_a)
D. (V = E_gR_a/I_a)
Questions with Correct Answers
(VerifiedAnswers) Plus Rationales 2026 Q&A
Instant Download PD
Question 1
What is the primary purpose of voltage regulation in a DC
generator?
A. To increase the mechanical speed of the generator
B. To reduce the generator's physical size
C. To maintain the terminal voltage within an acceptable range
as load changes
D. To eliminate all armature resistance
Rationale: Voltage regulation describes the ability of a DC
generator to maintain a relatively constant terminal voltage
when the load changes. As load current increases, internal
voltage drops caused by armature resistance and other effects
tend to reduce terminal voltage. A well-regulated generator
minimizes this change through appropriate design and
excitation. Mechanical speed and physical dimensions are not
the primary purposes of voltage regulation.
,Question 2
Which equation is commonly used to express the generated
EMF of a DC generator?
A. (E_g = V + I_aR_L)
B. (E_g = V/I_a)
C. (E_g = \frac{P\Phi ZN}{60A})
D. (E_g = I_aR_a)
Rationale: The generated EMF of a DC generator is given by
(E_g = P\Phi ZN/(60A)), where (P) is the number of poles, (\Phi)
is flux per pole, (Z) is the total armature conductors, (N) is speed
in revolutions per minute, and (A) is the number of parallel
paths. This equation shows that generated voltage depends
directly on flux and speed, while the winding configuration
affects the number of parallel paths.
Question 3
A DC generator produces an internal generated EMF of 250 V. If
its terminal voltage under load is 240 V, what is the internal
voltage drop?
A. 5 V
B. 10 V
,C. 20 V
D. 25 V
Rationale: The internal voltage drop is the difference between
generated EMF and terminal voltage. Therefore, (250 - 240 =
10) V. This difference represents the combined effects of internal
voltage drops such as armature resistance, brush contact
effects, and other machine losses that influence the voltage
available at the terminals.
Question 4
Which component of a DC generator is primarily responsible for
producing the magnetic field?
A. Commutator
B. Armature conductor
C. Field winding
D. Brush holder
Rationale: The field winding establishes the main magnetic field
in a conventional wound-field DC generator. Current through
the field winding creates magnetomotive force, which produces
magnetic flux. The armature interacts with this flux to generate
EMF. The commutator and brushes primarily provide
mechanical rectification and electrical connection rather than
creating the principal magnetic field.
, Question 5
What happens to the terminal voltage of a separately excited
DC generator when load current increases, assuming excitation
and speed remain constant?
A. It always increases substantially
B. It remains exactly constant
C. It generally decreases
D. It becomes zero immediately
Rationale: Increasing load current increases the voltage drop
across the armature resistance and brush contact resistance. In
addition, armature reaction can weaken or distort the main
magnetic field. Consequently, the generated and terminal
voltage available to the load generally decreases as load current
increases.
Question 6
Which expression most directly represents the terminal voltage
of a DC generator when brush voltage drop is neglected?
A. (V = E_g + I_aR_a)
B. (V = E_g - I_aR_a)
C. (V = I_a/R_a)
D. (V = E_gR_a/I_a)
