4th Class Power Engineering Unit A8
Chapter 4: Motors and Generators Exam
UPDATED QUESTIONS AND CORRECT
ANSWERS
As back EMF decreases the net armature EMF:
Select one:
a. remains constant
b. decreases
c. increases
d. decreases amount of armature current - CORRECT ANSWER c
The magnetic field in a DC machine may be supplied by permanent magnets in small units. Large DC
machines use field poles that are essentially:
Select one:
a. insulators
b. resistors
c. non-magnetic
d. electromagnets - CORRECT ANSWER d
The coils or windings on a DC machine armature, are placed in __________ cut in the face of the
armature:
Select one:
a. slots
b. holes
c. pairs
d. sequence - CORRECT ANSWER a
Compound motors combine the characteristics of shunt and _________motors, as desired by the
designer:
Select one:
,a. AC
b. DC
c. parallel
d. series - CORRECT ANSWER d
When synchronizing an alternator; voltage, and frequency must all be the same as well as:
Select one:
a. phase sequence
b. speed
c. current
d. power - CORRECT ANSWER a
The rotating field of an alternator is obtained by exciting the windings on the rotor with:
Select one:
a. AC power
b. stator current
c. magnetic particles
d. DC power - CORRECT ANSWER d
The load current has no effect on the field excitation of a:
Select one:
a. compound wound generator
b. series wound generator
c. shunt wound generator
d. separately excited generator - CORRECT ANSWER d
The field rheostat changes the ___________ in a DC generator:
Select one:
a. output voltage
b. input voltage
, c. output current
d. input resistance - CORRECT ANSWER a
Three phase systems often use__________ to replace three-phase transformers:
Select one:
a. capacitors
b. pancake windings
c. Sandwich windings
d. banks of single-phase - CORRECT ANSWER d
When AC action causes a counter current in a coil it is termed:
Select one:
a. self-inductance
b. capacitance
c. hysteresis
d. current generation - CORRECT ANSWER a
The electromagnets for a DC machine are termed the:
Select one:
a. armatures
b. yokes
c. field poles
d. brush gears - CORRECT ANSWER c
Power is supplied to a circuit at 240 V. The current drawn is 190 A while the current doing actual
work is 170 A. What is the active power:
Select one:
a. 80.4 kW
b. 40.8 kW
c. 8.4 kW
d. 4.8 kW - CORRECT ANSWER b
Chapter 4: Motors and Generators Exam
UPDATED QUESTIONS AND CORRECT
ANSWERS
As back EMF decreases the net armature EMF:
Select one:
a. remains constant
b. decreases
c. increases
d. decreases amount of armature current - CORRECT ANSWER c
The magnetic field in a DC machine may be supplied by permanent magnets in small units. Large DC
machines use field poles that are essentially:
Select one:
a. insulators
b. resistors
c. non-magnetic
d. electromagnets - CORRECT ANSWER d
The coils or windings on a DC machine armature, are placed in __________ cut in the face of the
armature:
Select one:
a. slots
b. holes
c. pairs
d. sequence - CORRECT ANSWER a
Compound motors combine the characteristics of shunt and _________motors, as desired by the
designer:
Select one:
,a. AC
b. DC
c. parallel
d. series - CORRECT ANSWER d
When synchronizing an alternator; voltage, and frequency must all be the same as well as:
Select one:
a. phase sequence
b. speed
c. current
d. power - CORRECT ANSWER a
The rotating field of an alternator is obtained by exciting the windings on the rotor with:
Select one:
a. AC power
b. stator current
c. magnetic particles
d. DC power - CORRECT ANSWER d
The load current has no effect on the field excitation of a:
Select one:
a. compound wound generator
b. series wound generator
c. shunt wound generator
d. separately excited generator - CORRECT ANSWER d
The field rheostat changes the ___________ in a DC generator:
Select one:
a. output voltage
b. input voltage
, c. output current
d. input resistance - CORRECT ANSWER a
Three phase systems often use__________ to replace three-phase transformers:
Select one:
a. capacitors
b. pancake windings
c. Sandwich windings
d. banks of single-phase - CORRECT ANSWER d
When AC action causes a counter current in a coil it is termed:
Select one:
a. self-inductance
b. capacitance
c. hysteresis
d. current generation - CORRECT ANSWER a
The electromagnets for a DC machine are termed the:
Select one:
a. armatures
b. yokes
c. field poles
d. brush gears - CORRECT ANSWER c
Power is supplied to a circuit at 240 V. The current drawn is 190 A while the current doing actual
work is 170 A. What is the active power:
Select one:
a. 80.4 kW
b. 40.8 kW
c. 8.4 kW
d. 4.8 kW - CORRECT ANSWER b
