SYNCHRONOUS GENERATORS 27 



rated armature voltage per pole? What is the form factor of this 

 e.m.f.? Sketch the graphs of the flux density and the e.m.f. 



(b) Compare this e.m.f. and form factor with what they would 

 have been had the winding been concentrated i.e., with 4 induc- 

 tors in series per pole placed in the same slot. 



21. In problem 19 if the armature winding consists of 4 induc- 

 tors in series per pole placed in alternate slots, what is the gene- 

 rated armature voltage per pole? What is the form factor of 

 this e.m.f.? Sketch the graphs of the flux density and the e.m.f. 



(b) Compare this e.m.f. and form factor with what they would 

 have been had the winding been concentrated i.e., with 4 induc- 

 tors in series per pole placed in the same slot. 



22. With normal excitation the resultant air-gap flux in a 60- 

 cycle alternator is 10* lines per pole. The flux density is con- 

 stant under the pole face and decreases uniformly to zero at points 

 midway between the poles. The armature has 8 equally spaced 

 slots per pole. The ratio of pole arc to pole pitch is 0.67 and the 

 coil pitch is 1.0. 



If the armature winding consists of 2 inductors in series per 

 pole placed in adjacent slots, what is the generated armature 

 voltage per pole? What is the form factor of this e.m.f.? 

 Sketch the graphs of the flux density and the e.m.f. 



23. With normal excitation the resultant air-gap flux in a 

 60-cycle alternator is 10 6 lines per pole and is sinusoidally dis- 

 tributed along the air-gap. The armature has 12 equally spaced 

 slots per pole. The coil pitch is 1 .0. 



(a) If the armature winding consists of 6 inductors in series 

 per pole placed in alternate slots, what is the generated armature 

 voltage per pole? What is the form factor of this e.m.f.? 



(b) Compare this e.m.f. with what it would have been had the 

 inductors per pole been concentrated in one slot. 



24. In problem 23 if the armature winding consists of 12 

 inductors in series per pole, one in each slot, what is the generated 

 armature voltage per pole? What is the form factor of this 

 e.m.f.? 



(b) Compare this e.m.f. with what it would have been had the 

 12 inductors per pole been concentrated in one slot. 



25. In problem 23 if the armature winding consists of 8 

 inductors in series per pole placed in adjacent slots, what is the 

 generated armature voltage per pole? What is the form factor 

 of this e.m.f.? 



