Analyse the operation of simple DC and AC generators and AC induction motors

Analyse the operation of simple DC and AC generators and AC induction motors

AC-generator
  • The parts of a generator are same as motor
  • Current is generated by spinning central point (rotor – wire coiled around armature) in a stationary (stator – magnet) section
  • Change in magnetic flux produces induced current which is transferred through slip rings
  • Both ends of the coil are connected to separate slip-rings which co-rotate with the coil

DC-generator

  • The parts of a generator are same as motor
  • Current is generated by spinning central point (rotor – wire coiled around armature) in a stationary (stator – magnet) section
  • Change in magnetic flux produces induced current which is transferred through a single ring

split-ring-commutator

  • the two ends of the coil are attached to different halves of a single split-ring which co-rotates with the coil

AC induction motor

  • Synchronous
    • Has a rotor and stator
    • Similar to DC
    • Uses slip ring instead of split ring
    • Coils around core produces AC current
    • Polarity changes with current which gives a constant rotation
  • Induction
    • Rotor
      • Squirrel cage (copper bars attached to rings) encased in iron (laminated)
      • Eddy currents induced by changing magnetic field and flow from one end to the other
      • They produce an opposing magnetic field which is attracted and dragged along by the initial field.
    • Stator
      • External electro magnet which produces the changing magnetic field
      • 3 phase version has 3 sets of coils surrounding the rotor which creates torque with a rotating field.

Extract from Physics Stage 6 Syllabus © 2017 NSW Education Standards Authority (NESA)