PROCEDURE IN DESIGN OF D.C. GENERATOR 229 



Chap. Ill, Art. 16, in connection with the horseshoe lifting mag- 

 net. The useful flux entering the armature must be multiplied 

 by the leakage factor to obtain the total flux in the yoke ring; 

 and, in the case of the pole cores, the approximation suggested 

 in Art. 16 (page 60) may be used. The average value of the 

 pole-core density, for use in calculating the ampere-turns required, 

 is 



2B, + B p 

 B,= -3 







In this instance B v = 1.2B P ', whence B c = 1.133B P , the mean- 

 ing of which is that the density in the pole core is calculated 

 on the assumption that the leakage factor is 1.133 instead of 

 1.2, as used for estimating the flux in the frame. 



OPEN-CIRCUIT SATURATION 

 (Table for Calculating Ampere-turns per Pole for Total Magnetic Circuit) 



