NCCER ELECTRICAL MODULE 2
LEVEL 2 MOTORS: THEORY AND
APPLICATION EXAM
How DC motors operate? - Correct Answers -Magnetic lines of force are continuous and
always form closed loops; Magnetic lines of force do not cross.
Armature: (Definition) - Correct Answers -The rotating windings of a DC motor.
The ____ is a movable electromagnet located between the poles of another fixed
permanent (field) magnet as shown. - Correct Answers -Armature
A twisting force called ______ must be developed. _____ is produced by mounting a
loop in a fixed magnetic field and as long as the fields of the magnet and armature
interact. - Correct Answers -Torque
Commentator: (Definition) - Correct Answers -A device used on electric motors or
generators to maintain a unidirectional current.
In the neutral plane, no ____ is produced and the rotation of the armature should stop -
Correct Answers -Torque
A _____ is produced by the fields poles, and a loop of wire in the armature turns and
cuts this magnetic field. - Correct Answers -Magnetic field
CEMF - Correct Answers -Counter electromotive force (CEMF)
Horsepower: (Definition) - Correct Answers -The rated output capacity of the motor. It is
based on breakdown torque, which is the maximum torque a motor will develop without
an abrupt drop in speed.
Horsepower: (Equation) - Correct Answers -Hp= Watts/746
Types of DC motors - Correct Answers -Shunt
Series
Compound
Types of AC motors - Correct Answers -Synchronous and Induction (Single and
Polyphase)
, Periodic duty: (Definition) - Correct Answers -Intermittent operation at a substantially
constant load for a short and definitely specified time.
Revolutions per minute (rpm): (Definition) - Correct Answers -The approximate full-load
speed at the rated power line frequency. The speed of a motor is determined by the
number of poles in the winding.
Rotation: (Definition) - Correct Answers -For single-phase motors, the standard rotation,
unless otherwise noted, is counterclockwise facing the lead or opposite shaft end. All
motors can be reconnected at the terminal board for opposite rotation unless other wise
indicated.
Synchronous speed: (Definition) - Correct Answers -The speed of the revolving field of
the stator, which is dependent on the supply frequency and number of poles in a stator
winding.
Field poles: (Definition) - Correct Answers -The stationary portion of a DC motor that
produces the magnetic field.
The name of the motor part that rotates during operation is the ____. - Correct Answers
-Armature
The principle reason for developing the brushless DC motor was to ___. - Correct
Answers -eliminate commutator problems
The electrical energy required to produce 1hp of mechanical energy is _____. - Correct
Answers -746W
When there is a wide variation in both torque and speed requirements, such as a blower
or hoist, use a _____. - Correct Answers -series DC motor
The name of the stationary motor part that produces the magnetic field during operation
is the ____. - Correct Answers -stator
The rpm of a 60Hz motor with two poles is ___. - Correct Answers -3,600rpm
In three-phase motors, the rotor most commonly used is the _____. - Correct Answers -
squirrel cage rotor
The starting torque characteristics of a wound-rotor motor are defined by _____. -
Correct Answers -rotor resistance
A three-phase synchronous motor is started with a(n) _____. - Correct Answers -
amortisseur winding
LEVEL 2 MOTORS: THEORY AND
APPLICATION EXAM
How DC motors operate? - Correct Answers -Magnetic lines of force are continuous and
always form closed loops; Magnetic lines of force do not cross.
Armature: (Definition) - Correct Answers -The rotating windings of a DC motor.
The ____ is a movable electromagnet located between the poles of another fixed
permanent (field) magnet as shown. - Correct Answers -Armature
A twisting force called ______ must be developed. _____ is produced by mounting a
loop in a fixed magnetic field and as long as the fields of the magnet and armature
interact. - Correct Answers -Torque
Commentator: (Definition) - Correct Answers -A device used on electric motors or
generators to maintain a unidirectional current.
In the neutral plane, no ____ is produced and the rotation of the armature should stop -
Correct Answers -Torque
A _____ is produced by the fields poles, and a loop of wire in the armature turns and
cuts this magnetic field. - Correct Answers -Magnetic field
CEMF - Correct Answers -Counter electromotive force (CEMF)
Horsepower: (Definition) - Correct Answers -The rated output capacity of the motor. It is
based on breakdown torque, which is the maximum torque a motor will develop without
an abrupt drop in speed.
Horsepower: (Equation) - Correct Answers -Hp= Watts/746
Types of DC motors - Correct Answers -Shunt
Series
Compound
Types of AC motors - Correct Answers -Synchronous and Induction (Single and
Polyphase)
, Periodic duty: (Definition) - Correct Answers -Intermittent operation at a substantially
constant load for a short and definitely specified time.
Revolutions per minute (rpm): (Definition) - Correct Answers -The approximate full-load
speed at the rated power line frequency. The speed of a motor is determined by the
number of poles in the winding.
Rotation: (Definition) - Correct Answers -For single-phase motors, the standard rotation,
unless otherwise noted, is counterclockwise facing the lead or opposite shaft end. All
motors can be reconnected at the terminal board for opposite rotation unless other wise
indicated.
Synchronous speed: (Definition) - Correct Answers -The speed of the revolving field of
the stator, which is dependent on the supply frequency and number of poles in a stator
winding.
Field poles: (Definition) - Correct Answers -The stationary portion of a DC motor that
produces the magnetic field.
The name of the motor part that rotates during operation is the ____. - Correct Answers
-Armature
The principle reason for developing the brushless DC motor was to ___. - Correct
Answers -eliminate commutator problems
The electrical energy required to produce 1hp of mechanical energy is _____. - Correct
Answers -746W
When there is a wide variation in both torque and speed requirements, such as a blower
or hoist, use a _____. - Correct Answers -series DC motor
The name of the stationary motor part that produces the magnetic field during operation
is the ____. - Correct Answers -stator
The rpm of a 60Hz motor with two poles is ___. - Correct Answers -3,600rpm
In three-phase motors, the rotor most commonly used is the _____. - Correct Answers -
squirrel cage rotor
The starting torque characteristics of a wound-rotor motor are defined by _____. -
Correct Answers -rotor resistance
A three-phase synchronous motor is started with a(n) _____. - Correct Answers -
amortisseur winding
