DC Motors Flashcards
What is the rotor of a DC motor generally made from?
Coils of wire
What does Maxwell’s Right Hand Grip Rule indicate?
Shows the direction of a magnetic field around the conductor.
What will limes of magnetic flux never do?
Never cross
Using Fleming’s Left Hamd Rule, what does each digit indicate?
Thumb - motion
First finger - magnetic field
Second finger - direction of current
What is Back EMF?
The induced EMF will be opposite in polarity to the EMF applied to the conduction externally.
The amount of torque produced by a motor is dependent upon what two things?
Strength of the magnetic field
Magnitude of armature current
List the 3 classifications of DC motors.
Series
Shunt
Compound
What must the carbon brushes be fixed in the same position as? And why?
Must stay on the Magnetic neutral axis to ensure that the coil passes under the brush whilst it has no current passing through it.
Describe armature reaction.
Interpoles assist in giving sparkless communication by neutralising the effect of armature reaction and allows a fixed brush position.
What are inter- poles, where are they fitted and what do they do?
Between the main poles and wound in series with the armature in order that their effect will offset that of the varying armature current.
Sketch and label the Maxwell’s Corkscrew Rule
Sketch and label The Left Hand Rule
Sketch and label single loop DC motor.
Label the AC motor parts.
