The stator of a synchronous machine consists of a laminated electrical steel core and a three phase winding. Fig.(a) below shows a stator lamination of a synchronous machine that has a number of uniformly distributed slots. Coils are to be laid in these slots and connected in such a way that the current in each phase winding would produce a magnetic field in the air gap around the stator periphery as closely as possible the ideal sinusoidal distribution. Fig.(b) is a picture of a coil.