NEIEP 400 FINAL EXAM VERSION 1 2026/2027 | Latest
Update | Verified Questions & Answers | 100% Correct
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SECTION 1: DC GENERATORS — THEORY & OPERATION (30
Questions)
Q1: A DC generator converts which form of energy into electrical energy?
A. Thermal energy into mechanical energy
B. Mechanical energy into electrical energy [CORRECT]
C. Chemical energy into thermal energy
D. Electrical energy into mechanical energy
Correct Answer: B
Rationale: A DC generator is a rotating electrical machine that converts mechanical
energy (typically from a prime mover or motor) into direct current electrical energy
through electromagnetic induction. Distractor A confuses thermal and mechanical
processes. Distractor C describes battery operation. Distractor D describes the function
of a DC motor, which is the reverse operation of a generator.
Q2: In a self-excited DC generator, how do the pole pieces initially become magnetized
to begin the generation process?
A. By applying an external DC battery to the field winding
B. By residual magnetism retained in the pole pieces [CORRECT]
C. By passing AC current through the armature winding
D. By manually striking the pole pieces with a hammer
Correct Answer: B
Rationale: Self-excited generators rely on residual magnetism—small amounts of
magnetic flux remaining in the pole pieces from previous operation—to initiate voltage
buildup. As the armature rotates, this residual field induces a small EMF, which feeds
current into the field winding, strengthening the field progressively. Distractor A
,describes separately excited generators. Distractor C is incorrect because AC cannot
produce DC excitation. Distractor D is a physical impossibility for magnetic excitation.
Q3: Which type of DC generator requires a separate external power source to energize
the field winding?
A. Self-excited shunt generator
B. Series-wound generator
C. Separately excited generator [CORRECT]
D. Compound-wound generator
Correct Answer: C
Rationale: A separately excited generator has its field winding connected to an
independent DC power source, providing precise voltage control independent of
generator output. Distractor A derives field excitation from the generator's own output.
Distractor B uses the load current for excitation. Distractor D combines self-excitation
methods and does not require an external source.
Q4: In a shunt generator, what happens to the output voltage as the electrical load
increases?
A. The output voltage increases proportionally
B. The output voltage remains absolutely constant
C. The output voltage drops as load increases [CORRECT]
D. The output voltage reverses polarity
Correct Answer: C
Rationale: Shunt generator output voltage decreases with increasing load due to three
factors: increased armature voltage drop (IaRa), increased armature reaction
demagnetizing effect, and reduced field current caused by the lower terminal voltage.
Distractor A describes an over-compounded generator. Distractor B is impossible due to
internal losses. Distractor D would require a complete reversal of rotation or field
connections.
Q5: In a series-wound DC generator, current flows through the series field winding only
when:
A. The generator is operating at no-load
B. The generator is rotating at synchronous speed
,C. There is an electrical load connected to the output [CORRECT]
D. The field rheostat is at maximum resistance
Correct Answer: C
Rationale: The series field winding is connected in series with the armature and external
load; therefore, current flows through it only when a load is connected and drawing
current. At no-load (Distractor A), no current flows through the series field. Distractor B
confuses DC generator operation with AC synchronous machines. Distractor D affects
field strength in shunt generators but does not determine whether current flows in a
series circuit.
Q6: A compound-wound DC generator used in elevator applications is intentionally
over-compounded to ensure that:
A. The generator produces maximum voltage at no-load
B. An empty car travels slower in the down direction near terminal landings [CORRECT]
C. The motor operates at constant speed regardless of load
D. The brake releases before the motor starts
Correct Answer: B
Rationale: Over-compounding in elevator generators intentionally creates a drooping
voltage characteristic that slows an empty car (light load) in the down direction near
terminal landings, providing smoother, safer terminal approach control. Distractor A
describes a flat-compound or separately excited characteristic. Distractor C describes a
different control philosophy not achieved by over-compounding alone. Distractor D
describes a mechanical brake control sequence unrelated to generator compounding.
Q7: In a compound-wound generator, the series field is connected:
A. In parallel with the armature only
B. In series with the shunt field only
C. In parallel with the series field shunt and in series with the armature [CORRECT]
D. In parallel with both the armature and shunt field
Correct Answer: C
Rationale: The series field winding is connected in series with the armature (carrying full
load current) and has a parallel shunt diverter resistor across it for adjustment. This
configuration allows the series field to respond to load current while the shunt diverter
, provides means to adjust the degree of compounding. Distractor A would make it a
shunt field. Distractor B would prevent armature current from flowing through the series
field. Distractor D would create a short-circuit path.
Q8: The field protective relay in an elevator DC generator control system is connected in
series with the:
A. Armature circuit
B. Motor shunt field [CORRECT]
C. Series field diverter
D. Main line contactor coil
Correct Answer: B
Rationale: The field protective relay (also called field loss relay or field failure relay) is
wired in series with the motor shunt field to detect loss of field current. If field current
drops below a safe value, the relay opens to prevent dangerous overspeeding of the
motor due to weakened field flux. Distractor A would protect against armature overload,
not field failure. Distractor C monitors diverter current, not field integrity. Distractor D is
a control circuit element, not a protective relay location.
Q9: Which factor primarily causes the voltage droop characteristic in a shunt generator
as load increases?
A. Decreasing residual magnetism
B. Armature resistance drop and armature reaction [CORRECT]
C. Increasing field circuit resistance
D. Reverse rotation of the armature
Correct Answer: B
Rationale: The primary causes of voltage droop in shunt generators are: (1) voltage drop
across armature resistance (IaRa), and (2) the demagnetizing effect of armature
reaction (cross-magnetizing flux distortion). Distractor A affects initial buildup but not
steady-state droop. Distractor C would only occur if the field rheostat were being
adjusted. Distractor D would reverse polarity, not merely reduce voltage.
Q10: The direction of generated voltage in a DC generator can be reversed by:
A. Increasing the field current
B. Reversing the field connections or reversing the direction of rotation [CORRECT]
Update | Verified Questions & Answers | 100% Correct
Grade A | Pass Guaranteed - A+ Graded
SECTION 1: DC GENERATORS — THEORY & OPERATION (30
Questions)
Q1: A DC generator converts which form of energy into electrical energy?
A. Thermal energy into mechanical energy
B. Mechanical energy into electrical energy [CORRECT]
C. Chemical energy into thermal energy
D. Electrical energy into mechanical energy
Correct Answer: B
Rationale: A DC generator is a rotating electrical machine that converts mechanical
energy (typically from a prime mover or motor) into direct current electrical energy
through electromagnetic induction. Distractor A confuses thermal and mechanical
processes. Distractor C describes battery operation. Distractor D describes the function
of a DC motor, which is the reverse operation of a generator.
Q2: In a self-excited DC generator, how do the pole pieces initially become magnetized
to begin the generation process?
A. By applying an external DC battery to the field winding
B. By residual magnetism retained in the pole pieces [CORRECT]
C. By passing AC current through the armature winding
D. By manually striking the pole pieces with a hammer
Correct Answer: B
Rationale: Self-excited generators rely on residual magnetism—small amounts of
magnetic flux remaining in the pole pieces from previous operation—to initiate voltage
buildup. As the armature rotates, this residual field induces a small EMF, which feeds
current into the field winding, strengthening the field progressively. Distractor A
,describes separately excited generators. Distractor C is incorrect because AC cannot
produce DC excitation. Distractor D is a physical impossibility for magnetic excitation.
Q3: Which type of DC generator requires a separate external power source to energize
the field winding?
A. Self-excited shunt generator
B. Series-wound generator
C. Separately excited generator [CORRECT]
D. Compound-wound generator
Correct Answer: C
Rationale: A separately excited generator has its field winding connected to an
independent DC power source, providing precise voltage control independent of
generator output. Distractor A derives field excitation from the generator's own output.
Distractor B uses the load current for excitation. Distractor D combines self-excitation
methods and does not require an external source.
Q4: In a shunt generator, what happens to the output voltage as the electrical load
increases?
A. The output voltage increases proportionally
B. The output voltage remains absolutely constant
C. The output voltage drops as load increases [CORRECT]
D. The output voltage reverses polarity
Correct Answer: C
Rationale: Shunt generator output voltage decreases with increasing load due to three
factors: increased armature voltage drop (IaRa), increased armature reaction
demagnetizing effect, and reduced field current caused by the lower terminal voltage.
Distractor A describes an over-compounded generator. Distractor B is impossible due to
internal losses. Distractor D would require a complete reversal of rotation or field
connections.
Q5: In a series-wound DC generator, current flows through the series field winding only
when:
A. The generator is operating at no-load
B. The generator is rotating at synchronous speed
,C. There is an electrical load connected to the output [CORRECT]
D. The field rheostat is at maximum resistance
Correct Answer: C
Rationale: The series field winding is connected in series with the armature and external
load; therefore, current flows through it only when a load is connected and drawing
current. At no-load (Distractor A), no current flows through the series field. Distractor B
confuses DC generator operation with AC synchronous machines. Distractor D affects
field strength in shunt generators but does not determine whether current flows in a
series circuit.
Q6: A compound-wound DC generator used in elevator applications is intentionally
over-compounded to ensure that:
A. The generator produces maximum voltage at no-load
B. An empty car travels slower in the down direction near terminal landings [CORRECT]
C. The motor operates at constant speed regardless of load
D. The brake releases before the motor starts
Correct Answer: B
Rationale: Over-compounding in elevator generators intentionally creates a drooping
voltage characteristic that slows an empty car (light load) in the down direction near
terminal landings, providing smoother, safer terminal approach control. Distractor A
describes a flat-compound or separately excited characteristic. Distractor C describes a
different control philosophy not achieved by over-compounding alone. Distractor D
describes a mechanical brake control sequence unrelated to generator compounding.
Q7: In a compound-wound generator, the series field is connected:
A. In parallel with the armature only
B. In series with the shunt field only
C. In parallel with the series field shunt and in series with the armature [CORRECT]
D. In parallel with both the armature and shunt field
Correct Answer: C
Rationale: The series field winding is connected in series with the armature (carrying full
load current) and has a parallel shunt diverter resistor across it for adjustment. This
configuration allows the series field to respond to load current while the shunt diverter
, provides means to adjust the degree of compounding. Distractor A would make it a
shunt field. Distractor B would prevent armature current from flowing through the series
field. Distractor D would create a short-circuit path.
Q8: The field protective relay in an elevator DC generator control system is connected in
series with the:
A. Armature circuit
B. Motor shunt field [CORRECT]
C. Series field diverter
D. Main line contactor coil
Correct Answer: B
Rationale: The field protective relay (also called field loss relay or field failure relay) is
wired in series with the motor shunt field to detect loss of field current. If field current
drops below a safe value, the relay opens to prevent dangerous overspeeding of the
motor due to weakened field flux. Distractor A would protect against armature overload,
not field failure. Distractor C monitors diverter current, not field integrity. Distractor D is
a control circuit element, not a protective relay location.
Q9: Which factor primarily causes the voltage droop characteristic in a shunt generator
as load increases?
A. Decreasing residual magnetism
B. Armature resistance drop and armature reaction [CORRECT]
C. Increasing field circuit resistance
D. Reverse rotation of the armature
Correct Answer: B
Rationale: The primary causes of voltage droop in shunt generators are: (1) voltage drop
across armature resistance (IaRa), and (2) the demagnetizing effect of armature
reaction (cross-magnetizing flux distortion). Distractor A affects initial buildup but not
steady-state droop. Distractor C would only occur if the field rheostat were being
adjusted. Distractor D would reverse polarity, not merely reduce voltage.
Q10: The direction of generated voltage in a DC generator can be reversed by:
A. Increasing the field current
B. Reversing the field connections or reversing the direction of rotation [CORRECT]
