induction motor

Discussion in 'Homework Help' started by Geney, Sep 21, 2012.

  1. Geney

    Thread Starter New Member

    Apr 2, 2012
    18
    0
    why is the starting current of an induction motor very high?? what is its approximate value?
     
  2. cork_ie

    Member

    Oct 8, 2011
    348
    58
    Because there is no "Back EMF" until the motor is running

    Good instructional video here
    http://www.youtube.com/watch?v=07uXnc1C5CA

    Starting current will depend on motor size and load attached .

    eg Fan = low load.
    Air compressor = high load
     
  3. t_n_k

    AAC Fanatic!

    Mar 6, 2009
    5,448
    782
    At standstill the induction motor is essentially behaving as a transformer with a very low resistance secondary. With a wound rotor one can limit the starting current by connecting resistance in series with the rotor windings. The resistance would be switched out once operating steady state conditions are established. With the more common squirrel cage rotor one can limit the starting current on the stator side. DOL startup can produce very high starting current as you indicate.
     
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