214 



PRINCIPLES OF ELECTRICAL DESIGN 



The construction of the flux lines is as explained in Art. 41, page 

 129, and the measurements taken off the drawing have the follow- 

 ing values: 



m I k j i h 9 f e d c b a 



FIG. 79. Curves of air gap permeance and open circuit flux distribution. 



Item (69): Permeance Curve. Refer Art. 39. The curve 

 marked P in Fig. 79 has been plotted from the above figures. 

 It shows the variation of air-gap permeance between pole and 

 armature at all points from the center of pole face to a point, 

 m, 10 beyond the geometric neutral. 



Item (70): Actual Tooth Densities Refer Art. 37, page 119. 

 In order to make use of formula (62), giving the relation between 



