**Harmonic Analysis in Distributed Winding:**

The flux density wave of a synchronous machine is never exactly sine wave. Because of odd symmetry of poles (alternately north-south), the space Harmonic Analysis in Distributed Winding of the B-wave comprises odd harmonics only, which induce the corresponding harmonic emf s in the winding.

Figure 5.19 shows the fundamental B-wave, and its third-harmonic; because of somewhat flat-topped nature of the B-wave, its third-harmonic is of the “dipping” kind, producing a flux density dip in the middle of the main pole.

It follows from Fig. 5.19 that n poles of the nth harmonic occur in the space occupied by one pole of the fundamental. Thus,

It can be easily shown that K_{b }(nth harmonic) is less than K_{b }(fundamental) for important harmonics resulting in reduction of harmonic content of the voltage of the distributed winding—an incidental advantage.