Question { 21652 }

1. What is the difference between ac induction motor
and ac synchronous motor?

Answer

The basic difference between an induction motor(a.c) and a
synchronous AC motor is that in the latter a current is
supplied onto the rotor. This then creates a magnetic field
which, through magnetic interaction, links to the rotating
magnetic field in the stator which in turn causes the rotor
to turn. It is called synchronous because at steady state
the speed of the rotor is the same as the speed of the
rotating magnetic field in the stator.

By way of contrast, the induction motor does not have any
direct supply onto the rotor; instead, a secondary current
is induced in the rotor. To achieve this, stator windings
are arranged around the rotor so that when energised with a
polyphase supply they create a rotating magnetic field
pattern which sweeps past the rotor. This changing magnetic
field pattern can induce currents in the rotor conductors.
These currents interact with the rotating magnetic field
created by the stator and the rotor will turn.