Accor ding to double r evolving field t heor y, consider the two component of the stator flux, each having magnit ude half of maxi mum magnitude of stator flux i.e.
Ï•max
2
. Both of these components are r otating in apposite direction at synchr onous speed NS, at stating of single phase induction motor. So, single phase induction motor not self start by any mean single phase induction motor rotate to synchr onous speed and starting winding disconnected and only main winding excited then forword rotation field is more then Backword rotating field and motor will start in for ward Direction.