204 PRINCIPLES OF ELECTRICAL DESIGN 



DESIGN SHEET FOR CONTINUOUS-CURRENT GENERATOR. Continued 



63. Numerical Example Calculations. Items (6) and (7): 

 Number of Poles. Refer to table in Art. 20 (page 81). Usual 

 number; 4 or 6. On page 78 in same article, the frequency is 

 stated to be generally between 10 and 40. With four poles, 



A f* f\C\ 



f = 2 X -7>Q-, which is satisfactory. 



Item (8): Ratio of Pole Arc to Pole Pitch. Refer Art. 19, 

 pages 74 and 76. Since there are no interpoles, we shall make 

 r = 0.72. 



Item (9) : Specific Loading. Refer Art. 19, pages 74 and 76. 

 For 75-kw. machine, try q 475. 



