How DC motors operate?
Magnetic lines of force are continuous and always form closed loops; Magnetic lines of force do not cross.
Armature: (Definition)
The rotating windings of a DC motor.
The ____ is a movable electromagnet located between the poles of another fixed permanent (fie...
NCCER Electrical Module 2 Level 2 Motors Theory and Application exam questions and answers
How DC motors operate? - answer Magnetic lines of force are continuous and always form closed loops; Magnetic lines of force do not cross.
Armature: (Definition) - answer The rotating windings of a DC motor.
The ____ is a movable electromagnet located between the poles of another fixed permanent (field) magnet as shown. - answer 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. - answer Torque
Commentator: (Definition) - answer 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 - answer
Torque
A _____ is produced by the fields poles, and a loop of wire in the armature turns and cuts this magnetic field. - answer Magnetic field
CEMF - answer Counter electromotive force (CEMF)
Horsepower: (Definition) - answer 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) - answer Hp= Watts/746
Types of DC motors - answer Shunt
Series
Compound
Types of AC motors - answer Synchronous and Induction (Single and Polyphase)
Periodic duty: (Definition) - answer Intermittent operation at a substantially constant load for a short and definitely specified time.
Revolutions per minute (rpm): (Definition) - answer 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) - answer 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) - answer 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) - answer The stationary portion of a DC motor that produces the magnetic field.
The name of the motor part that rotates during operation is the ____. - answer Armature
The principle reason for developing the brushless DC motor was to ___. - answer eliminate commutator problems
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