CHAP. IV] 



INDUCED E.M.F. 



71 



eral the winding-pitch be t^, expressed as a fraction. Then 

 7-= (1 Q180 . Substituting this value of /- into formula (35) we 

 obtain 



-;)] . (36) 



The values of k w given in Fig. 19 have been calculated according 

 to this formula. 



i.oo 



BUBO 



0.70 



10 



70 80 



Per Cent Winding Pitch 



jo 



Fio. 19. Values of the winding-pitch factor. 



In applications, one takes the value of k t from the table, assum- 

 ing the winding pitch to be one hundred per cent, and multiplies it 

 by the value of k w taken from the curve (Fig. 19). With frac- 

 tional-pitch two-layer windings the value of k t corresponds to the 

 nuinlxT <>f --lots per layer per pole per phase, and not to the total 

 n u ml>er of slots per pole per phase. This is d< -:u -from t he ex plan a- 



ivm in tlir pn-crrlinir paragraph. Thus, fur instan. 

 16, k, must be taken for three slots and not for five slots. If nr 

 has to calculate the values of k b often, it is advisable to plot a set 



