MOTORS Flashcards
An electric motor is a machine for converting electrical energy into what?
mechanical energy
What are the two main reasons for using AC motors?
- Maintenance
- Efficiency
An AC motor has two main components, what are they?
- Stator
- Rotor
What is the main disadvantage of an AC induction motor?
Very difficult to vary the speed
What is the supply used to connect the stator for motor operation?
3 Phase
What do the three sets of phase coils do (Red, Yellow, Blue) in a motor stator?
Produce rotating magnetic field
What is the most common type of AC motor used on HM ships?
Squirrel cage
What causes rotation in a 3 phase induction motor?
rotating magnetic field
There is no electrical connection to the rotor in an AC motor, what advantage does this provide?
less maintenance
In the squirrel cage induction motor, the rotor is made of thin strips of steel, what is the rotor (armature) of a DC motor made up of?
wire
What does Maxwell’s Right Hand Grip rule tell us?
Thumb - current, Fingers - magnetic field
When a conductor carrying a current is placed in a field of a fixed magnet, do the magnetic lines of force cross each other?
False
What will be the interaction of two magnetic fields?
- Crowd together
- Cancel out
What does the elementary DC motor consist of?
Coil between two poles of a magnet
What is Armature Reaction?
Flowing current in armature crosses a magnetic field
Why must the brushes stay on the Magnetic Neutral Axis?
The coil passes under the brush with no current
What is the purpose of interpoles?
Smaller than main poles, wound in series
