Discussion in 'Homework Help' started by Geney, Sep 21, 2012.
why is the starting current of an induction motor very high?? what is its approximate value?
Because there is no "Back EMF" until the motor is running
Good instructional video here
Starting current will depend on motor size and load attached .
eg Fan = low load.
Air compressor = high load
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.