MODULE 6 IQ 5 Flashcards
What are generators
Device which converts mechanical energy into electrical energy by applying the principle of electromagnetic induction.
What type of commutator is in a AC generator
Slip-ring commutator
What is a slip-ring commutator
Two cylindrical metal conductors that rotate freely with the armature. They produce constant electrical contact between the rotating armature and external circuit.
What is an AC induction motor
Use AC current as opposed to DC current in DC motors
Rotor of AC induction motor
Assembly of parallel conductors and rigs, producing a shape similar to that of a ‘squirrel cage’
Stator of AC induction motor
Stationary electrical component, which is made of pairs of electromagnets, connected to an AC power supply
Coils of AC induction motor
Coils are wound around the electromagnets in such a way that when a current flows through the coils, one coil would be the North Pole and its pair a South Pole.
Operation of AC induction motors
One pair of electromagnets is fed AC current to produce a magnetic field, while the remaining two pairs do not. The pair is then turned off and adjacent pair is turned on, producing a rotating magnetic field.
Faraday’s law in AC induction motors
The rotating magnetic field induces an EMF and a current inside the squirrel cage rotor
Lenz’s law in AC induction motors
This induced magnetic field opposes the change that causes it, causing the rotor to spin in the same direction as the rotating magnetic field
Slip speed
Difference in rotational speed between the magnetic field and rotor